diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 00000000000..3ad05109d47
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,2 @@
+_build
+_install
diff --git a/.github/scripts/flags-clang.sh b/.github/scripts/flags-clang.sh
index d083672e4dc..039c4740c39 100644
--- a/.github/scripts/flags-clang.sh
+++ b/.github/scripts/flags-clang.sh
@@ -9,6 +9,9 @@ add_flag -Weverything
 
 # Disable specific warning flags for both C and C++.
 
+# TODO(iphydf): Investigate these.
+add_flag -Wno-unsafe-buffer-usage
+
 # Very verbose, not very useful. This warns about things like int -> uint
 # conversions that change sign without a cast and narrowing conversions.
 add_flag -Wno-conversion
diff --git a/.github/scripts/flags.sh b/.github/scripts/flags.sh
index 80a56c017df..d2af1292c48 100644
--- a/.github/scripts/flags.sh
+++ b/.github/scripts/flags.sh
@@ -29,7 +29,7 @@ add_flag -O3 -march=native
 # Warn on non-ISO C.
 add_c_flag -pedantic
 add_c_flag -std=c99
-add_cxx_flag -std=c++11
+add_cxx_flag -std=c++17
 
 add_flag -g3
 add_flag -ftrapv
diff --git a/BUILD.bazel b/BUILD.bazel
index 4d39dab3332..472347b04b7 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -8,19 +8,49 @@ project()
 genrule(
     name = "public_headers",
     srcs = [
+        "toxav.h",
+        "tox.h",
+        "toxencryptsave.h",
         "//c-toxcore/toxav:toxav.h",
         "//c-toxcore/toxcore:tox.h",
+        "//c-toxcore/toxcore:tox_attributes.h",
+        "//c-toxcore/toxcore:tox_logger.h",
+        "//c-toxcore/toxcore:tox_memory.h",
+        "//c-toxcore/toxcore:tox_network.h",
+        "//c-toxcore/toxcore:tox_random.h",
+        "//c-toxcore/toxcore:tox_system.h",
+        "//c-toxcore/toxcore:tox_time.h",
         "//c-toxcore/toxencryptsave:toxencryptsave.h",
     ],
     outs = [
         "tox/toxav.h",
         "tox/tox.h",
         "tox/toxencryptsave.h",
+        "tox/toxav/toxav.h",
+        "tox/toxcore/tox.h",
+        "tox/toxcore/tox_attributes.h",
+        "tox/toxcore/tox_logger.h",
+        "tox/toxcore/tox_memory.h",
+        "tox/toxcore/tox_network.h",
+        "tox/toxcore/tox_random.h",
+        "tox/toxcore/tox_system.h",
+        "tox/toxcore/tox_time.h",
+        "tox/toxencryptsave/toxencryptsave.h",
     ],
     cmd = """
-        cp $(location //c-toxcore/toxav:toxav.h) $(GENDIR)/c-toxcore/tox/toxav.h
-        cp $(location //c-toxcore/toxcore:tox.h) $(GENDIR)/c-toxcore/tox/tox.h
-        cp $(location //c-toxcore/toxencryptsave:toxencryptsave.h) $(GENDIR)/c-toxcore/tox/toxencryptsave.h
+        cp $(location toxav.h) $(GENDIR)/c-toxcore/tox/toxav.h
+        cp $(location tox.h) $(GENDIR)/c-toxcore/tox/tox.h
+        cp $(location toxencryptsave.h) $(GENDIR)/c-toxcore/tox/toxencryptsave.h
+        cp $(location //c-toxcore/toxav:toxav.h) $(GENDIR)/c-toxcore/tox/toxav/toxav.h
+        cp $(location //c-toxcore/toxcore:tox.h) $(GENDIR)/c-toxcore/tox/toxcore/tox.h
+        cp $(location //c-toxcore/toxcore:tox_attributes.h) $(GENDIR)/c-toxcore/tox/toxcore/tox_attributes.h
+        cp $(location //c-toxcore/toxcore:tox_logger.h) $(GENDIR)/c-toxcore/tox/toxcore/tox_logger.h
+        cp $(location //c-toxcore/toxcore:tox_memory.h) $(GENDIR)/c-toxcore/tox/toxcore/tox_memory.h
+        cp $(location //c-toxcore/toxcore:tox_network.h) $(GENDIR)/c-toxcore/tox/toxcore/tox_network.h
+        cp $(location //c-toxcore/toxcore:tox_random.h) $(GENDIR)/c-toxcore/tox/toxcore/tox_random.h
+        cp $(location //c-toxcore/toxcore:tox_system.h) $(GENDIR)/c-toxcore/tox/toxcore/tox_system.h
+        cp $(location //c-toxcore/toxcore:tox_time.h) $(GENDIR)/c-toxcore/tox/toxcore/tox_time.h
+        cp $(location //c-toxcore/toxencryptsave:toxencryptsave.h) $(GENDIR)/c-toxcore/tox/toxencryptsave/toxencryptsave.h
     """,
     visibility = ["//visibility:public"],
 )
diff --git a/CMakeLists.txt b/CMakeLists.txt
index d3cabf06c66..8c18fe0fa02 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -282,6 +282,17 @@ set(toxcore_SOURCES
   toxcore/onion_client.c
   toxcore/onion_client.h
   toxcore/onion.h
+  toxcore/os_logger.c
+  toxcore/os_logger.h
+  toxcore/os_memory.c
+  toxcore/os_memory.h
+  toxcore/os_network.c
+  toxcore/os_network.h
+  toxcore/os_network_impl.h
+  toxcore/os_random.c
+  toxcore/os_random.h
+  toxcore/os_system.c
+  toxcore/os_system.h
   toxcore/ping_array.c
   toxcore/ping_array.h
   toxcore/ping.c
@@ -302,11 +313,29 @@ set(toxcore_SOURCES
   toxcore/timed_auth.h
   toxcore/tox_api.c
   toxcore/tox.c
+  toxcore/tox.h
   toxcore/tox_dispatch.c
   toxcore/tox_dispatch.h
   toxcore/tox_events.c
   toxcore/tox_events.h
-  toxcore/tox.h
+  toxcore/tox_logger.c
+  toxcore/tox_logger.h
+  toxcore/tox_logger_impl.h
+  toxcore/tox_memory.c
+  toxcore/tox_memory.h
+  toxcore/tox_memory_impl.h
+  toxcore/tox_network.c
+  toxcore/tox_network.h
+  toxcore/tox_network_impl.h
+  toxcore/tox_random.c
+  toxcore/tox_random.h
+  toxcore/tox_random_impl.h
+  toxcore/tox_system.c
+  toxcore/tox_system.h
+  toxcore/tox_system_impl.h
+  toxcore/tox_time.c
+  toxcore/tox_time.h
+  toxcore/tox_time_impl.h
   toxcore/tox_private.c
   toxcore/tox_private.h
   toxcore/tox_unpack.c
@@ -317,8 +346,14 @@ set(toxcore_LINK_MODULES ${toxcore_LINK_MODULES} ${LIBSODIUM_LIBRARIES})
 set(toxcore_PKGCONFIG_REQUIRES ${toxcore_PKGCONFIG_REQUIRES} libsodium)
 set(toxcore_API_HEADERS
   ${toxcore_SOURCE_DIR}/toxcore/tox.h^tox
+  ${toxcore_SOURCE_DIR}/toxcore/tox_dispatch.h^tox
   ${toxcore_SOURCE_DIR}/toxcore/tox_events.h^tox
-  ${toxcore_SOURCE_DIR}/toxcore/tox_dispatch.h^tox)
+  ${toxcore_SOURCE_DIR}/toxcore/tox_logger.h^tox
+  ${toxcore_SOURCE_DIR}/toxcore/tox_memory.h^tox
+  ${toxcore_SOURCE_DIR}/toxcore/tox_network.h^tox
+  ${toxcore_SOURCE_DIR}/toxcore/tox_random.h^tox
+  ${toxcore_SOURCE_DIR}/toxcore/tox_system.h^tox
+  ${toxcore_SOURCE_DIR}/toxcore/tox_time.h^tox)
 
 ################################################################################
 #
diff --git a/auto_tests/BUILD.bazel b/auto_tests/BUILD.bazel
index babd3aca845..d5731890e78 100644
--- a/auto_tests/BUILD.bazel
+++ b/auto_tests/BUILD.bazel
@@ -19,6 +19,7 @@ cc_library(
         "//c-toxcore/toxcore:Messenger",
         "//c-toxcore/toxcore:mono_time",
         "//c-toxcore/toxcore:tox",
+        "//c-toxcore/toxcore:tox_time",
     ],
 )
 
@@ -61,9 +62,13 @@ flaky_tests = {
         "//c-toxcore/toxcore:onion",
         "//c-toxcore/toxcore:onion_announce",
         "//c-toxcore/toxcore:onion_client",
+        "//c-toxcore/toxcore:os_memory",
+        "//c-toxcore/toxcore:os_network",
+        "//c-toxcore/toxcore:os_random",
         "//c-toxcore/toxcore:tox",
         "//c-toxcore/toxcore:tox_dispatch",
         "//c-toxcore/toxcore:tox_events",
+        "//c-toxcore/toxcore:tox_time",
         "//c-toxcore/toxcore:util",
         "//c-toxcore/toxencryptsave",
         "@libsodium",
diff --git a/auto_tests/TCP_test.c b/auto_tests/TCP_test.c
index d5455cf0e83..dfa3d7b96b8 100644
--- a/auto_tests/TCP_test.c
+++ b/auto_tests/TCP_test.c
@@ -8,6 +8,9 @@
 #include "../toxcore/TCP_server.h"
 #include "../toxcore/crypto_core.h"
 #include "../toxcore/mono_time.h"
+#include "../toxcore/os_random.h"
+#include "../toxcore/os_network.h"
+#include "../toxcore/os_memory.h"
 #include "../toxcore/util.h"
 #include "auto_test_support.h"
 
@@ -45,14 +48,14 @@ static uint16_t ports[NUM_PORTS] = {13215, 33445, 25643};
 
 static void test_basic(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
-    const Network *ns = system_network();
+    const Network *ns = os_network();
     ck_assert(ns != nullptr);
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     ck_assert(mem != nullptr);
 
-    Mono_Time *mono_time = mono_time_new(mem, nullptr, nullptr);
+    Mono_Time *mono_time = mono_time_new(mem, nullptr);
     Logger *logger = logger_new();
     logger_callback_log(logger, print_debug_logger, nullptr, nullptr);
 
@@ -303,14 +306,14 @@ static int read_packet_sec_TCP(const Logger *logger, struct sec_TCP_con *con, ui
 
 static void test_some(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
-    const Network *ns = system_network();
+    const Network *ns = os_network();
     ck_assert(ns != nullptr);
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     ck_assert(mem != nullptr);
 
-    Mono_Time *mono_time = mono_time_new(mem, nullptr, nullptr);
+    Mono_Time *mono_time = mono_time_new(mem, nullptr);
     Logger *logger = logger_new();
 
     uint8_t self_public_key[CRYPTO_PUBLIC_KEY_SIZE];
@@ -498,15 +501,15 @@ static int oob_data_callback(void *object, const uint8_t *public_key, const uint
 
 static void test_client(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
-    const Network *ns = system_network();
+    const Network *ns = os_network();
     ck_assert(ns != nullptr);
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     ck_assert(mem != nullptr);
 
     Logger *logger = logger_new();
-    Mono_Time *mono_time = mono_time_new(mem, nullptr, nullptr);
+    Mono_Time *mono_time = mono_time_new(mem, nullptr);
 
     uint8_t self_public_key[CRYPTO_PUBLIC_KEY_SIZE];
     uint8_t self_secret_key[CRYPTO_SECRET_KEY_SIZE];
@@ -632,14 +635,14 @@ static void test_client(void)
 // Test how the client handles servers that don't respond.
 static void test_client_invalid(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
-    const Network *ns = system_network();
+    const Network *ns = os_network();
     ck_assert(ns != nullptr);
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     ck_assert(mem != nullptr);
 
-    Mono_Time *mono_time = mono_time_new(mem, nullptr, nullptr);
+    Mono_Time *mono_time = mono_time_new(mem, nullptr);
     Logger *logger = logger_new();
 
     uint8_t self_public_key[CRYPTO_PUBLIC_KEY_SIZE];
@@ -711,14 +714,14 @@ static int tcp_data_callback(void *object, int id, const uint8_t *data, uint16_t
 
 static void test_tcp_connection(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
-    const Network *ns = system_network();
+    const Network *ns = os_network();
     ck_assert(ns != nullptr);
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     ck_assert(mem != nullptr);
 
-    Mono_Time *mono_time = mono_time_new(mem, nullptr, nullptr);
+    Mono_Time *mono_time = mono_time_new(mem, nullptr);
     Logger *logger = logger_new();
 
     tcp_data_callback_called = 0;
@@ -824,14 +827,14 @@ static int tcp_oobdata_callback(void *object, const uint8_t *public_key, unsigne
 
 static void test_tcp_connection2(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
-    const Network *ns = system_network();
+    const Network *ns = os_network();
     ck_assert(ns != nullptr);
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     ck_assert(mem != nullptr);
 
-    Mono_Time *mono_time = mono_time_new(mem, nullptr, nullptr);
+    Mono_Time *mono_time = mono_time_new(mem, nullptr);
     Logger *logger = logger_new();
 
     tcp_oobdata_callback_called = 0;
diff --git a/auto_tests/announce_test.c b/auto_tests/announce_test.c
index f0929c757c6..97fa9fe76a1 100644
--- a/auto_tests/announce_test.c
+++ b/auto_tests/announce_test.c
@@ -7,13 +7,16 @@
 #include "../toxcore/mono_time.h"
 #include "../toxcore/forwarding.h"
 #include "../toxcore/net_crypto.h"
+#include "../toxcore/os_memory.h"
+#include "../toxcore/os_network.h"
+#include "../toxcore/os_random.h"
 #include "../toxcore/util.h"
 #include "auto_test_support.h"
 #include "check_compat.h"
 
 static void test_bucketnum(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
     uint8_t key1[CRYPTO_PUBLIC_KEY_SIZE], key2[CRYPTO_PUBLIC_KEY_SIZE];
     random_bytes(rng, key1, sizeof(key1));
@@ -50,17 +53,17 @@ static void test_announce_data(void *object, const uint8_t *data, uint16_t lengt
 
 static void test_store_data(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
-    const Network *ns = system_network();
+    const Network *ns = os_network();
     ck_assert(ns != nullptr);
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     ck_assert(mem != nullptr);
 
     Logger *log = logger_new();
     ck_assert(log != nullptr);
     logger_callback_log(log, print_debug_logger, nullptr, nullptr);
-    Mono_Time *mono_time = mono_time_new(mem, nullptr, nullptr);
+    Mono_Time *mono_time = mono_time_new(mem, nullptr);
     Networking_Core *net = new_networking_no_udp(log, mem, ns);
     DHT *dht = new_dht(log, mem, rng, ns, mono_time, net, true, true);
     Forwarding *forwarding = new_forwarding(log, rng, mono_time, dht);
diff --git a/auto_tests/auto_test_support.c b/auto_tests/auto_test_support.c
index cb409738ef4..b7d52b9c089 100644
--- a/auto_tests/auto_test_support.c
+++ b/auto_tests/auto_test_support.c
@@ -6,6 +6,7 @@
 #include "../toxcore/Messenger.h"
 #include "../toxcore/mono_time.h"
 #include "../toxcore/tox_struct.h"
+#include "../toxcore/tox_time_impl.h"
 
 #include "auto_test_support.h"
 
@@ -13,7 +14,7 @@
 #define ABORT_ON_LOG_ERROR true
 #endif
 
-Run_Auto_Options default_run_auto_options()
+Run_Auto_Options default_run_auto_options(void)
 {
     return (Run_Auto_Options) {
         .graph = GRAPH_COMPLETE,
@@ -159,15 +160,23 @@ static uint64_t get_state_clock_callback(void *user_data)
     return *clock;
 }
 
+static const Tox_Time_Funcs autotox_time_funcs = {
+    get_state_clock_callback,
+};
+
 void set_mono_time_callback(AutoTox *autotox)
 {
     ck_assert(autotox != nullptr);
 
+    if (autotox->tm == nullptr) {
+        autotox->tm = tox_time_new(&autotox_time_funcs, &autotox->clock, autotox->tox->sys.mem);
+    }
+
     Mono_Time *mono_time = autotox->tox->mono_time;
 
     autotox->clock = current_time_monotonic(mono_time);
-    mono_time_set_current_time_callback(mono_time, nullptr, nullptr);  // set to default first
-    mono_time_set_current_time_callback(mono_time, get_state_clock_callback, &autotox->clock);
+    mono_time_set_current_time_callback(mono_time, nullptr);  // set to default first
+    mono_time_set_current_time_callback(mono_time, autotox->tm);
 }
 
 void save_autotox(AutoTox *autotox)
@@ -193,6 +202,8 @@ void kill_autotox(AutoTox *autotox)
     fprintf(stderr, "Killing #%u\n", autotox->index);
     autotox->alive = false;
     tox_kill(autotox->tox);
+    tox_time_free(autotox->tm);
+    autotox->tm = nullptr;
 }
 
 void reload(AutoTox *autotox)
@@ -380,6 +391,7 @@ void run_auto_test(struct Tox_Options *options, uint32_t tox_count, void test(Au
 
     for (uint32_t i = 0; i < tox_count; ++i) {
         tox_kill(autotoxes[i].tox);
+        tox_time_free(autotoxes[i].tm);
         free(autotoxes[i].state);
         free(autotoxes[i].save_state);
     }
diff --git a/auto_tests/auto_test_support.h b/auto_tests/auto_test_support.h
index eab121aa367..10a250a0ffa 100644
--- a/auto_tests/auto_test_support.h
+++ b/auto_tests/auto_test_support.h
@@ -10,6 +10,7 @@
 
 typedef struct AutoTox {
     Tox *tox;
+    Tox_Time *tm;
 
     uint32_t index;
     uint64_t clock;
diff --git a/auto_tests/conference_av_test.c b/auto_tests/conference_av_test.c
index 9bbc4182699..2fbcd5e7f21 100644
--- a/auto_tests/conference_av_test.c
+++ b/auto_tests/conference_av_test.c
@@ -7,6 +7,7 @@
 #include <stdint.h>
 
 #include "../toxav/toxav.h"
+#include "../toxcore/os_random.h"
 #include "check_compat.h"
 
 #define NUM_AV_GROUP_TOX 16
@@ -287,7 +288,7 @@ static void do_audio(AutoTox *autotoxes, uint32_t iterations)
 
 static void run_conference_tests(AutoTox *autotoxes)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
     bool disabled[NUM_AV_GROUP_TOX] = {0};
 
diff --git a/auto_tests/conference_test.c b/auto_tests/conference_test.c
index 66edddd85c7..d7e3fe6283c 100644
--- a/auto_tests/conference_test.c
+++ b/auto_tests/conference_test.c
@@ -6,6 +6,7 @@
 #include <time.h>
 #include <stdint.h>
 
+#include "../toxcore/os_random.h"
 #include "../toxcore/util.h"
 
 #include "check_compat.h"
@@ -192,7 +193,7 @@ static uint32_t random_false_index(const Random *rng, bool *list, const uint32_t
 
 static void run_conference_tests(AutoTox *autotoxes)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
     /* disabling name change propagation check for now, as it occasionally
      * fails due to disconnections too short to trigger freezing */
diff --git a/auto_tests/crypto_test.c b/auto_tests/crypto_test.c
index f4fdf3e22de..546259d06d9 100644
--- a/auto_tests/crypto_test.c
+++ b/auto_tests/crypto_test.c
@@ -4,6 +4,7 @@
 
 #include "../testing/misc_tools.h"
 #include "../toxcore/crypto_core.h"
+#include "../toxcore/os_random.h"
 #include "../toxcore/net_crypto.h"
 #include "check_compat.h"
 
@@ -129,7 +130,7 @@ static void test_fast_known(void)
 
 static void test_endtoend(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
 
     // Test 100 random messages and keypairs
@@ -196,7 +197,7 @@ static void test_endtoend(void)
 
 static void test_large_data(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
     uint8_t k[CRYPTO_SHARED_KEY_SIZE];
     uint8_t n[CRYPTO_NONCE_SIZE];
@@ -240,7 +241,7 @@ static void test_large_data(void)
 
 static void test_large_data_symmetric(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
     uint8_t k[CRYPTO_SYMMETRIC_KEY_SIZE];
 
@@ -296,7 +297,7 @@ static void increment_nonce_number_cmp(uint8_t *nonce, uint32_t num)
 
 static void test_increment_nonce(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
 
     uint32_t i;
diff --git a/auto_tests/encryptsave_test.c b/auto_tests/encryptsave_test.c
index fb49c4e2af2..cd56f65710b 100644
--- a/auto_tests/encryptsave_test.c
+++ b/auto_tests/encryptsave_test.c
@@ -9,6 +9,7 @@
 #include "../testing/misc_tools.h"
 #include "../toxcore/ccompat.h"
 #include "../toxcore/crypto_core.h"
+#include "../toxcore/os_random.h"
 #include "../toxcore/tox.h"
 #include "../toxencryptsave/toxencryptsave.h"
 #include "auto_test_support.h"
@@ -169,7 +170,7 @@ static void test_keys(void)
     ck_assert(encrypted2a != nullptr);
     uint8_t *in_plaintext2a = (uint8_t *)malloc(plaintext_length2a);
     ck_assert(in_plaintext2a != nullptr);
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
     random_bytes(rng, in_plaintext2a, plaintext_length2a);
     ret = tox_pass_encrypt(in_plaintext2a, plaintext_length2a, key_char, 12, encrypted2a, &encerr);
diff --git a/auto_tests/forwarding_test.c b/auto_tests/forwarding_test.c
index f9c82784f20..40a2a01fa26 100644
--- a/auto_tests/forwarding_test.c
+++ b/auto_tests/forwarding_test.c
@@ -8,6 +8,9 @@
 #include "../toxcore/mono_time.h"
 #include "../toxcore/forwarding.h"
 #include "../toxcore/net_crypto.h"
+#include "../toxcore/os_memory.h"
+#include "../toxcore/os_network.h"
+#include "../toxcore/os_random.h"
 #include "../toxcore/util.h"
 #include "auto_test_support.h"
 #include "check_compat.h"
@@ -104,9 +107,9 @@ typedef struct Forwarding_Subtox {
 
 static Forwarding_Subtox *new_forwarding_subtox(const Memory *mem, bool no_udp, uint32_t *index, uint16_t port)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
-    const Network *ns = system_network();
+    const Network *ns = os_network();
     ck_assert(ns != nullptr);
 
     Forwarding_Subtox *subtox = (Forwarding_Subtox *)calloc(1, sizeof(Forwarding_Subtox));
@@ -115,7 +118,7 @@ static Forwarding_Subtox *new_forwarding_subtox(const Memory *mem, bool no_udp,
     subtox->log = logger_new();
     ck_assert(subtox->log != nullptr);
     logger_callback_log(subtox->log, print_debug_logger, nullptr, index);
-    subtox->mono_time = mono_time_new(mem, nullptr, nullptr);
+    subtox->mono_time = mono_time_new(mem, nullptr);
 
     if (no_udp) {
         subtox->net = new_networking_no_udp(subtox->log, mem, ns);
@@ -152,11 +155,11 @@ static void kill_forwarding_subtox(const Memory *mem, Forwarding_Subtox *subtox)
 
 static void test_forwarding(void)
 {
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     ck_assert(mem != nullptr);
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
-    const Network *ns = system_network();
+    const Network *ns = os_network();
     ck_assert(ns != nullptr);
 
     uint32_t index[NUM_FORWARDER];
diff --git a/auto_tests/group_message_test.c b/auto_tests/group_message_test.c
index d7a00a9fee0..8d5d7cc64d3 100644
--- a/auto_tests/group_message_test.c
+++ b/auto_tests/group_message_test.c
@@ -12,6 +12,7 @@
 
 #include "auto_test_support.h"
 #include "check_compat.h"
+#include "../toxcore/os_random.h"
 #include "../toxcore/util.h"
 
 typedef struct State {
@@ -334,7 +335,7 @@ static void group_message_test(AutoTox *autotoxes)
 #ifndef VANILLA_NACL
     ck_assert_msg(NUM_GROUP_TOXES >= 2, "NUM_GROUP_TOXES is too small: %d", NUM_GROUP_TOXES);
 
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
 
     Tox *tox0 = autotoxes[0].tox;
diff --git a/auto_tests/group_sync_test.c b/auto_tests/group_sync_test.c
index 4d2bc1866dc..fdd895ed344 100644
--- a/auto_tests/group_sync_test.c
+++ b/auto_tests/group_sync_test.c
@@ -10,6 +10,7 @@
 
 #include "auto_test_support.h"
 
+#include "../toxcore/os_random.h"
 #include "../toxcore/tox.h"
 #include "../toxcore/util.h"
 
@@ -332,7 +333,7 @@ static void group_sync_test(AutoTox *autotoxes)
 {
 #ifndef VANILLA_NACL
     ck_assert(NUM_GROUP_TOXES >= 5);
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
 
     for (size_t i = 0; i < NUM_GROUP_TOXES; ++i) {
diff --git a/auto_tests/group_topic_test.c b/auto_tests/group_topic_test.c
index 26dafcb459a..00fff8555d8 100644
--- a/auto_tests/group_topic_test.c
+++ b/auto_tests/group_topic_test.c
@@ -11,8 +11,9 @@
 #include "auto_test_support.h"
 #include "check_compat.h"
 
-#include "../toxcore/tox.h"
 #include "../toxcore/group_chats.h"
+#include "../toxcore/os_random.h"
+#include "../toxcore/tox.h"
 
 #define NUM_GROUP_TOXES 3
 
@@ -206,7 +207,7 @@ static void group_topic_test(AutoTox *autotoxes)
 #ifndef VANILLA_NACL
     ck_assert_msg(NUM_GROUP_TOXES >= 3, "NUM_GROUP_TOXES is too small: %d", NUM_GROUP_TOXES);
 
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
 
     Tox *tox0 = autotoxes[0].tox;
diff --git a/auto_tests/lan_discovery_test.c b/auto_tests/lan_discovery_test.c
index d7bf594b2bf..8ea4e39764c 100644
--- a/auto_tests/lan_discovery_test.c
+++ b/auto_tests/lan_discovery_test.c
@@ -3,6 +3,8 @@
 
 #include "../testing/misc_tools.h"
 #include "../toxcore/ccompat.h"
+#include "../toxcore/os_memory.h"
+#include "../toxcore/tox_time_impl.h"
 #include "../toxcore/tox_struct.h"
 #include "auto_test_support.h"
 
@@ -12,6 +14,10 @@ static uint64_t get_state_clock_callback(void *user_data)
     return *clock;
 }
 
+static const Tox_Time_Funcs mock_time_funcs = {
+    get_state_clock_callback,
+};
+
 int main(void)
 {
     setvbuf(stdout, nullptr, _IONBF, 0);
@@ -21,14 +27,18 @@ int main(void)
     ck_assert(tox1 != nullptr);
     ck_assert(tox2 != nullptr);
 
+    const Memory *mem = os_memory();
+
     uint64_t clock = current_time_monotonic(tox1->mono_time);
+    Tox_Time *tm = tox_time_new(&mock_time_funcs, &clock, mem);
+
     Mono_Time *mono_time;
 
     mono_time = tox1->mono_time;
-    mono_time_set_current_time_callback(mono_time, get_state_clock_callback, &clock);
+    mono_time_set_current_time_callback(mono_time, tm);
 
     mono_time = tox2->mono_time;
-    mono_time_set_current_time_callback(mono_time, get_state_clock_callback, &clock);
+    mono_time_set_current_time_callback(mono_time, tm);
 
     printf("Waiting for LAN discovery. This loop will attempt to run until successful.");
 
@@ -49,5 +59,7 @@ int main(void)
 
     tox_kill(tox2);
     tox_kill(tox1);
+
+    tox_time_free(tm);
     return 0;
 }
diff --git a/auto_tests/network_test.c b/auto_tests/network_test.c
index df3b625a9e1..f96618385e2 100644
--- a/auto_tests/network_test.c
+++ b/auto_tests/network_test.c
@@ -3,6 +3,7 @@
 
 #include "../testing/misc_tools.h"
 #include "../toxcore/network.h"
+#include "../toxcore/os_network.h"
 #include "check_compat.h"
 
 #ifndef USE_IPV6
@@ -20,7 +21,7 @@ static void test_addr_resolv_localhost(void)
     errno = 0;
 #endif
 
-    const Network *ns = system_network();
+    const Network *ns = os_network();
     ck_assert(ns != nullptr);
 
     const char localhost[] = "localhost";
diff --git a/auto_tests/onion_test.c b/auto_tests/onion_test.c
index 282b99637e6..720b907b548 100644
--- a/auto_tests/onion_test.c
+++ b/auto_tests/onion_test.c
@@ -6,6 +6,9 @@
 #include "../toxcore/onion.h"
 #include "../toxcore/onion_announce.h"
 #include "../toxcore/onion_client.h"
+#include "../toxcore/os_memory.h"
+#include "../toxcore/os_network.h"
+#include "../toxcore/os_random.h"
 #include "../toxcore/util.h"
 #include "auto_test_support.h"
 #include "check_compat.h"
@@ -223,11 +226,11 @@ static Networking_Core *new_networking(const Logger *log, const Memory *mem, con
 static void test_basic(void)
 {
     uint32_t index[] = { 1, 2, 3 };
-    const Network *ns = system_network();
+    const Network *ns = os_network();
     ck_assert(ns != nullptr);
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     ck_assert(mem != nullptr);
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
 
     Logger *log1 = logger_new();
@@ -235,8 +238,8 @@ static void test_basic(void)
     Logger *log2 = logger_new();
     logger_callback_log(log2, print_debug_logger, nullptr, &index[1]);
 
-    Mono_Time *mono_time1 = mono_time_new(mem, nullptr, nullptr);
-    Mono_Time *mono_time2 = mono_time_new(mem, nullptr, nullptr);
+    Mono_Time *mono_time1 = mono_time_new(mem, nullptr);
+    Mono_Time *mono_time2 = mono_time_new(mem, nullptr);
 
     IP ip = get_loopback();
     Onion *onion1 = new_onion(log1, mem, mono_time1, rng, new_dht(log1, mem, rng, ns, mono_time1, new_networking(log1, mem, ns, &ip, 36567), true, false));
@@ -334,7 +337,7 @@ static void test_basic(void)
     Logger *log3 = logger_new();
     logger_callback_log(log3, print_debug_logger, nullptr, &index[2]);
 
-    Mono_Time *mono_time3 = mono_time_new(mem, nullptr, nullptr);
+    Mono_Time *mono_time3 = mono_time_new(mem, nullptr);
 
     Onion *onion3 = new_onion(log3, mem, mono_time3, rng, new_dht(log3, mem, rng, ns, mono_time3, new_networking(log3, mem, ns, &ip, 36569), true, false));
     ck_assert_msg((onion3 != nullptr), "Onion failed initializing.");
@@ -407,7 +410,7 @@ static Onions *new_onions(const Memory *mem, const Random *rng, uint16_t port, u
 {
     IP ip = get_loopback();
     ip.ip.v6.uint8[15] = 1;
-    const Network *ns = system_network();
+    const Network *ns = os_network();
     Onions *on = (Onions *)malloc(sizeof(Onions));
 
     if (!on) {
@@ -423,7 +426,7 @@ static Onions *new_onions(const Memory *mem, const Random *rng, uint16_t port, u
 
     logger_callback_log(on->log, print_debug_logger, nullptr, index);
 
-    on->mono_time = mono_time_new(mem, nullptr, nullptr);
+    on->mono_time = mono_time_new(mem, nullptr);
 
     if (!on->mono_time) {
         logger_kill(on->log);
@@ -577,9 +580,9 @@ static void test_announce(void)
     uint32_t i, j;
     uint32_t index[NUM_ONIONS];
     Onions *onions[NUM_ONIONS];
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     ck_assert(mem != nullptr);
 
     for (i = 0; i < NUM_ONIONS; ++i) {
diff --git a/auto_tests/reconnect_test.c b/auto_tests/reconnect_test.c
index 253f66b0c5c..ad6a021f227 100644
--- a/auto_tests/reconnect_test.c
+++ b/auto_tests/reconnect_test.c
@@ -11,6 +11,7 @@
 
 #include "../testing/misc_tools.h"
 #include "../toxcore/friend_connection.h"
+#include "../toxcore/os_random.h"
 #include "../toxcore/tox.h"
 #include "../toxcore/util.h"
 #include "check_compat.h"
@@ -51,7 +52,7 @@ static bool all_disconnected_from(uint32_t tox_count, AutoTox *autotoxes, uint32
 
 static void test_reconnect(AutoTox *autotoxes)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
     const time_t test_start_time = time(nullptr);
 
diff --git a/auto_tests/save_friend_test.c b/auto_tests/save_friend_test.c
index 80a6ed037e8..4a546cc53c6 100644
--- a/auto_tests/save_friend_test.c
+++ b/auto_tests/save_friend_test.c
@@ -8,6 +8,7 @@
 #include "../testing/misc_tools.h"
 #include "../toxcore/ccompat.h"
 #include "../toxcore/crypto_core.h"
+#include "../toxcore/os_random.h"
 #include "../toxcore/tox.h"
 #include "auto_test_support.h"
 #include "check_compat.h"
@@ -86,7 +87,7 @@ int main(void)
     ck_assert(reference_name != nullptr);
     ck_assert(reference_status != nullptr);
 
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
     set_random(tox1, rng, tox_self_set_name, tox_max_name_length());
     set_random(tox2, rng, tox_self_set_name, tox_max_name_length());
diff --git a/auto_tests/save_load_test.c b/auto_tests/save_load_test.c
index 97077735633..41ac2bb48bf 100644
--- a/auto_tests/save_load_test.c
+++ b/auto_tests/save_load_test.c
@@ -8,8 +8,10 @@
 
 #include "../testing/misc_tools.h"
 #include "../toxcore/ccompat.h"
+#include "../toxcore/os_memory.h"
 #include "../toxcore/tox.h"
 #include "../toxcore/tox_struct.h"
+#include "../toxcore/tox_time_impl.h"
 #include "../toxcore/util.h"
 #include "auto_test_support.h"
 #include "check_compat.h"
@@ -119,6 +121,10 @@ static uint64_t get_state_clock_callback(void *user_data)
     return clock;
 }
 
+static const Tox_Time_Funcs mock_time_funcs = {
+    get_state_clock_callback,
+};
+
 static void increment_clock(Time_Data *time_data, uint64_t count)
 {
     pthread_mutex_lock(&time_data->lock);
@@ -126,10 +132,10 @@ static void increment_clock(Time_Data *time_data, uint64_t count)
     pthread_mutex_unlock(&time_data->lock);
 }
 
-static void set_current_time_callback(Tox *tox, Time_Data *time_data)
+static void set_current_time_callback(Tox *tox, Tox_Time *tm)
 {
     Mono_Time *mono_time = tox->mono_time;
-    mono_time_set_current_time_callback(mono_time, get_state_clock_callback, time_data);
+    mono_time_set_current_time_callback(mono_time, tm);
 }
 
 static void test_few_clients(void)
@@ -161,9 +167,12 @@ static void test_few_clients(void)
     Time_Data time_data;
     ck_assert_msg(pthread_mutex_init(&time_data.lock, nullptr) == 0, "Failed to init time_data mutex");
     time_data.clock = current_time_monotonic(tox1->mono_time);
-    set_current_time_callback(tox1, &time_data);
-    set_current_time_callback(tox2, &time_data);
-    set_current_time_callback(tox3, &time_data);
+
+    const Memory *mem = os_memory();
+    Tox_Time *tm = tox_time_new(&mock_time_funcs, &time_data, mem);
+    set_current_time_callback(tox1, tm);
+    set_current_time_callback(tox2, tm);
+    set_current_time_callback(tox3, tm);
 
     uint8_t dht_key[TOX_PUBLIC_KEY_SIZE];
     tox_self_get_dht_id(tox1, dht_key);
@@ -257,6 +266,8 @@ static void test_few_clients(void)
 
     tox_options_free(opts2);
     tox_options_free(opts3);
+
+    tox_time_free(tm);
 }
 
 int main(void)
diff --git a/auto_tests/tox_dispatch_test.c b/auto_tests/tox_dispatch_test.c
index 209e13788f2..c887176717b 100644
--- a/auto_tests/tox_dispatch_test.c
+++ b/auto_tests/tox_dispatch_test.c
@@ -43,7 +43,7 @@ static void dump_events(const char *path, const Tox_Events *events)
     }
 }
 
-static void print_events(const Tox_System *sys, Tox_Events *events)
+static void print_events(const struct Tox_System *sys, Tox_Events *events)
 {
     const uint32_t size = tox_events_bytes_size(events);
 
@@ -64,7 +64,7 @@ static void print_events(const Tox_System *sys, Tox_Events *events)
 
 static bool await_message(Tox **toxes, const Tox_Dispatch *dispatch)
 {
-    const Tox_System *sys = tox_get_system(toxes[0]);
+    const struct Tox_System *sys = tox_get_system(toxes[0]);
 
     for (uint32_t i = 0; i < 100; ++i) {
         // Ignore events on tox 1.
@@ -103,7 +103,7 @@ static void test_tox_events(void)
         ck_assert_msg(toxes[i] != nullptr, "failed to create tox instances %u", i);
     }
 
-    const Tox_System *sys = tox_get_system(toxes[0]);
+    const struct Tox_System *sys = tox_get_system(toxes[0]);
 
     Tox_Err_Dispatch_New err_new;
     Tox_Dispatch *dispatch = tox_dispatch_new(&err_new);
diff --git a/auto_tests/tox_events_test.c b/auto_tests/tox_events_test.c
index 04549b2179c..9bc211fd33d 100644
--- a/auto_tests/tox_events_test.c
+++ b/auto_tests/tox_events_test.c
@@ -7,9 +7,11 @@
 #include <time.h>
 
 #include "../testing/misc_tools.h"
+#include "../toxcore/os_memory.h"
 #include "../toxcore/tox.h"
 #include "../toxcore/tox_events.h"
 #include "../toxcore/tox_struct.h"
+#include "../toxcore/tox_time_impl.h"
 #include "auto_test_support.h"
 #include "check_compat.h"
 
@@ -43,6 +45,9 @@ static uint64_t get_state_clock_callback(void *user_data)
     const uint64_t *clock = (const uint64_t *)user_data;
     return *clock;
 }
+static const Tox_Time_Funcs mock_time_funcs = {
+    get_state_clock_callback,
+};
 
 static void test_tox_events(void)
 {
@@ -59,13 +64,17 @@ static void test_tox_events(void)
         ck_assert_msg(toxes[i] != nullptr, "failed to create tox instances %u", i);
     }
 
+    const Memory *mem = os_memory();
+
     uint64_t clock = current_time_monotonic(toxes[0]->mono_time);
+    Tox_Time *tm = tox_time_new(&mock_time_funcs, &clock, mem);
+
     Mono_Time *mono_time;
 
     mono_time = toxes[0]->mono_time;
-    mono_time_set_current_time_callback(mono_time, get_state_clock_callback, &clock);
+    mono_time_set_current_time_callback(mono_time, tm);
     mono_time = toxes[1]->mono_time;
-    mono_time_set_current_time_callback(mono_time, get_state_clock_callback, &clock);
+    mono_time_set_current_time_callback(mono_time, tm);
 
     uint8_t pk[TOX_PUBLIC_KEY_SIZE];
     tox_self_get_dht_id(toxes[0], pk);
@@ -113,6 +122,8 @@ static void test_tox_events(void)
     for (uint32_t i = 0; i < 2; ++i) {
         tox_kill(toxes[i]);
     }
+
+    tox_time_free(tm);
 }
 
 int main(void)
diff --git a/auto_tests/tox_many_tcp_test.c b/auto_tests/tox_many_tcp_test.c
index f466e3e1711..816707cb13b 100644
--- a/auto_tests/tox_many_tcp_test.c
+++ b/auto_tests/tox_many_tcp_test.c
@@ -8,6 +8,7 @@
 
 #include "../testing/misc_tools.h"
 #include "../toxcore/crypto_core.h"
+#include "../toxcore/os_random.h"
 #include "../toxcore/tox.h"
 #include "../toxcore/util.h"
 #include "auto_test_support.h"
@@ -41,7 +42,7 @@ static uint16_t tcp_relay_port = 33448;
 
 static void test_many_clients_tcp(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
     long long unsigned int cur_time = time(nullptr);
     Tox *toxes[NUM_TOXES_TCP];
@@ -144,7 +145,7 @@ static void test_many_clients_tcp(void)
 
 static void test_many_clients_tcp_b(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
     long long unsigned int cur_time = time(nullptr);
     Tox *toxes[NUM_TOXES_TCP];
diff --git a/auto_tests/tox_many_test.c b/auto_tests/tox_many_test.c
index 8501b5c172a..da44f23c4e2 100644
--- a/auto_tests/tox_many_test.c
+++ b/auto_tests/tox_many_test.c
@@ -8,6 +8,7 @@
 
 #include "../testing/misc_tools.h"
 #include "../toxcore/crypto_core.h"
+#include "../toxcore/os_random.h"
 #include "../toxcore/tox.h"
 #include "../toxcore/util.h"
 #include "auto_test_support.h"
@@ -26,7 +27,7 @@ static void accept_friend_request(Tox *m, const uint8_t *public_key, const uint8
 
 static void test_many_clients(void)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ck_assert(rng != nullptr);
     time_t cur_time = time(nullptr);
     Tox *toxes[TCP_TEST_NUM_TOXES];
diff --git a/auto_tests/toxav_many_test.c b/auto_tests/toxav_many_test.c
index 725fe61317f..30d36df5943 100644
--- a/auto_tests/toxav_many_test.c
+++ b/auto_tests/toxav_many_test.c
@@ -15,8 +15,10 @@
 #include "../toxav/toxav.h"
 #include "../toxcore/crypto_core.h"
 #include "../toxcore/logger.h"
+#include "../toxcore/os_memory.h"
 #include "../toxcore/tox.h"
 #include "../toxcore/tox_struct.h"
+#include "../toxcore/tox_time_impl.h"
 #include "../toxcore/util.h"
 #include "auto_test_support.h"
 #include "check_compat.h"
@@ -144,6 +146,10 @@ static uint64_t get_state_clock_callback(void *user_data)
     return clock;
 }
 
+static const Tox_Time_Funcs mock_time_funcs = {
+    get_state_clock_callback,
+};
+
 static void increment_clock(Time_Data *time_data, uint64_t count)
 {
     pthread_mutex_lock(&time_data->lock);
@@ -151,10 +157,10 @@ static void increment_clock(Time_Data *time_data, uint64_t count)
     pthread_mutex_unlock(&time_data->lock);
 }
 
-static void set_current_time_callback(Tox *tox, Time_Data *time_data)
+static void set_current_time_callback(Tox *tox, Tox_Time *tm)
 {
     Mono_Time *mono_time = tox->mono_time;
-    mono_time_set_current_time_callback(mono_time, get_state_clock_callback, time_data);
+    mono_time_set_current_time_callback(mono_time, tm);
 }
 
 static void test_av_three_calls(void)
@@ -168,6 +174,10 @@ static void test_av_three_calls(void)
 
     Time_Data time_data;
     pthread_mutex_init(&time_data.lock, nullptr);
+
+    const Memory *mem = os_memory();
+    Tox_Time *tm = tox_time_new(&mock_time_funcs, &time_data, mem);
+
     {
         Tox_Err_New error;
 
@@ -175,23 +185,23 @@ static void test_av_three_calls(void)
         ck_assert(error == TOX_ERR_NEW_OK);
 
         time_data.clock = current_time_monotonic(bootstrap->mono_time);
-        set_current_time_callback(bootstrap, &time_data);
+        set_current_time_callback(bootstrap, tm);
 
         Alice = tox_new_log(nullptr, &error, &index[1]);
         ck_assert(error == TOX_ERR_NEW_OK);
-        set_current_time_callback(Alice, &time_data);
+        set_current_time_callback(Alice, tm);
 
         Bobs[0] = tox_new_log(nullptr, &error, &index[2]);
         ck_assert(error == TOX_ERR_NEW_OK);
-        set_current_time_callback(Bobs[0], &time_data);
+        set_current_time_callback(Bobs[0], tm);
 
         Bobs[1] = tox_new_log(nullptr, &error, &index[3]);
         ck_assert(error == TOX_ERR_NEW_OK);
-        set_current_time_callback(Bobs[1], &time_data);
+        set_current_time_callback(Bobs[1], tm);
 
         Bobs[2] = tox_new_log(nullptr, &error, &index[4]);
         ck_assert(error == TOX_ERR_NEW_OK);
-        set_current_time_callback(Bobs[2], &time_data);
+        set_current_time_callback(Bobs[2], tm);
     }
 
     printf("Created 5 instances of Tox\n");
@@ -367,6 +377,8 @@ static void test_av_three_calls(void)
     tox_kill(Alice);
     tox_kill(bootstrap);
 
+    tox_time_free(tm);
+
     pthread_mutex_destroy(&time_data.lock);
 
     printf("\nTest successful!\n");
diff --git a/other/BUILD.bazel b/other/BUILD.bazel
index 1a8929a3758..4ed80ec49c4 100644
--- a/other/BUILD.bazel
+++ b/other/BUILD.bazel
@@ -28,6 +28,9 @@ cc_binary(
         "//c-toxcore/toxcore:mono_time",
         "//c-toxcore/toxcore:network",
         "//c-toxcore/toxcore:onion_announce",
+        "//c-toxcore/toxcore:os_memory",
+        "//c-toxcore/toxcore:os_network",
+        "//c-toxcore/toxcore:os_random",
         "//c-toxcore/toxcore:tox",
         "//c-toxcore/toxcore:util",
     ],
diff --git a/other/DHT_bootstrap.c b/other/DHT_bootstrap.c
index e59f9eedea2..7eca4a0cf58 100644
--- a/other/DHT_bootstrap.c
+++ b/other/DHT_bootstrap.c
@@ -20,6 +20,9 @@
 #include "../toxcore/group_onion_announce.h"
 #include "../toxcore/logger.h"
 #include "../toxcore/mono_time.h"
+#include "../toxcore/os_memory.h"
+#include "../toxcore/os_network.h"
+#include "../toxcore/os_random.h"
 #include "../toxcore/tox.h"
 #include "../toxcore/util.h"
 
@@ -143,11 +146,11 @@ int main(int argc, char *argv[])
         logger_callback_log(logger, print_log, nullptr, nullptr);
     }
 
-    const Random *rng = system_random();
-    const Network *ns = system_network();
-    const Memory *mem = system_memory();
+    const Random *rng = os_random();
+    const Network *ns = os_network();
+    const Memory *mem = os_memory();
 
-    Mono_Time *mono_time = mono_time_new(mem, nullptr, nullptr);
+    Mono_Time *mono_time = mono_time_new(mem, nullptr);
     const uint16_t start_port = PORT;
     const uint16_t end_port = start_port + (TOX_PORTRANGE_TO - TOX_PORTRANGE_FROM);
     DHT *dht = new_dht(logger, mem, rng, ns, mono_time, new_networking_ex(logger, mem, ns, &ip, start_port, end_port, nullptr), true, true);
diff --git a/other/bootstrap_daemon/BUILD.bazel b/other/bootstrap_daemon/BUILD.bazel
index e1a2e41f449..8e083558b77 100644
--- a/other/bootstrap_daemon/BUILD.bazel
+++ b/other/bootstrap_daemon/BUILD.bazel
@@ -19,6 +19,9 @@ cc_binary(
         "//c-toxcore/toxcore:logger",
         "//c-toxcore/toxcore:mono_time",
         "//c-toxcore/toxcore:onion_announce",
+        "//c-toxcore/toxcore:os_memory",
+        "//c-toxcore/toxcore:os_network",
+        "//c-toxcore/toxcore:os_random",
         "//c-toxcore/toxcore:tox",
         "//c-toxcore/toxcore:util",
         "@libconfig",
diff --git a/other/bootstrap_daemon/src/tox-bootstrapd.c b/other/bootstrap_daemon/src/tox-bootstrapd.c
index 7efd2c889d3..c799eb1f8f0 100644
--- a/other/bootstrap_daemon/src/tox-bootstrapd.c
+++ b/other/bootstrap_daemon/src/tox-bootstrapd.c
@@ -33,6 +33,9 @@
 #include "../../../toxcore/logger.h"
 #include "../../../toxcore/mono_time.h"
 #include "../../../toxcore/onion_announce.h"
+#include "../../../toxcore/os_memory.h"
+#include "../../../toxcore/os_network.h"
+#include "../../../toxcore/os_random.h"
 #include "../../../toxcore/util.h"
 
 // misc
@@ -280,9 +283,9 @@ int main(int argc, char *argv[])
     }
 
     const uint16_t end_port = start_port + (TOX_PORTRANGE_TO - TOX_PORTRANGE_FROM);
-    const Memory *mem = system_memory();
-    const Random *rng = system_random();
-    const Network *ns = system_network();
+    const Memory *mem = os_memory();
+    const Random *rng = os_random();
+    const Network *ns = os_network();
     Networking_Core *net = new_networking_ex(logger, mem, ns, &ip, start_port, end_port, nullptr);
 
     if (net == nullptr) {
@@ -310,7 +313,7 @@ int main(int argc, char *argv[])
         }
     }
 
-    Mono_Time *const mono_time = mono_time_new(mem, nullptr, nullptr);
+    Mono_Time *const mono_time = mono_time_new(mem, nullptr);
 
     if (mono_time == nullptr) {
         log_write(LOG_LEVEL_ERROR, "Couldn't initialize monotonic timer. Exiting.\n");
diff --git a/testing/BUILD.bazel b/testing/BUILD.bazel
index 68e89a15918..b9c0f63f31d 100644
--- a/testing/BUILD.bazel
+++ b/testing/BUILD.bazel
@@ -57,5 +57,8 @@ cc_binary(
         "//c-toxcore/toxcore:Messenger",
         "//c-toxcore/toxcore:ccompat",
         "//c-toxcore/toxcore:mono_time",
+        "//c-toxcore/toxcore:os_memory",
+        "//c-toxcore/toxcore:os_network",
+        "//c-toxcore/toxcore:os_random",
     ],
 )
diff --git a/testing/Messenger_test.c b/testing/Messenger_test.c
index 4c2c8f85ffb..a5548c86810 100644
--- a/testing/Messenger_test.c
+++ b/testing/Messenger_test.c
@@ -35,6 +35,9 @@
 #include "../toxcore/Messenger.h"
 #include "../toxcore/ccompat.h"
 #include "../toxcore/mono_time.h"
+#include "../toxcore/os_memory.h"
+#include "../toxcore/os_network.h"
+#include "../toxcore/os_random.h"
 #include "misc_tools.h"
 
 static void print_message(Messenger *m, uint32_t friendnumber, unsigned int type, const uint8_t *string, size_t length,
@@ -92,8 +95,8 @@ int main(int argc, char *argv[])
         exit(0);
     }
 
-    const Memory *mem = system_memory();
-    Mono_Time *const mono_time = mono_time_new(mem, nullptr, nullptr);
+    const Memory *mem = os_memory();
+    Mono_Time *const mono_time = mono_time_new(mem, nullptr);
 
     if (mono_time == nullptr) {
         fputs("Failed to allocate monotonic timer datastructure\n", stderr);
@@ -103,7 +106,7 @@ int main(int argc, char *argv[])
     Messenger_Options options = {0};
     options.ipv6enabled = ipv6enabled;
     Messenger_Error err;
-    m = new_messenger(mono_time, mem, system_random(), system_network(), &options, &err);
+    m = new_messenger(mono_time, mem, os_random(), os_network(), &options, &err);
 
     if (!m) {
         fprintf(stderr, "Failed to allocate messenger datastructure: %d\n", err);
diff --git a/testing/fuzzing/BUILD.bazel b/testing/fuzzing/BUILD.bazel
index 386516d72bf..68696f7ef09 100644
--- a/testing/fuzzing/BUILD.bazel
+++ b/testing/fuzzing/BUILD.bazel
@@ -15,7 +15,13 @@ cc_library(
     deps = [
         "//c-toxcore/toxcore:crypto_core",
         "//c-toxcore/toxcore:network",
+        "//c-toxcore/toxcore:os_network",
         "//c-toxcore/toxcore:tox",
+        "//c-toxcore/toxcore:tox_memory",
+        "//c-toxcore/toxcore:tox_network",
+        "//c-toxcore/toxcore:tox_random",
+        "//c-toxcore/toxcore:tox_system",
+        "//c-toxcore/toxcore:tox_time",
     ],
 )
 
diff --git a/testing/fuzzing/bootstrap_harness.cc b/testing/fuzzing/bootstrap_harness.cc
index 9ffb69d1f1b..ee98f84608b 100644
--- a/testing/fuzzing/bootstrap_harness.cc
+++ b/testing/fuzzing/bootstrap_harness.cc
@@ -107,6 +107,9 @@ void setup_callbacks(Tox_Dispatch *dispatch)
 
 void TestBootstrap(Fuzz_Data &input)
 {
+    // Null system for regularly working memory allocations needed in
+    // tox_events_equal.
+    Null_System null_sys;
     Fuzz_System sys(input);
 
     Ptr<Tox_Options> opts(tox_options_new(nullptr), tox_options_free);
@@ -154,11 +157,8 @@ void TestBootstrap(Fuzz_Data &input)
 
     uint8_t pub_key[TOX_PUBLIC_KEY_SIZE] = {0};
 
-    const bool udp_success = tox_bootstrap(tox, "127.0.0.2", 33446, pub_key, nullptr);
-    assert(udp_success);
-
-    const bool tcp_success = tox_add_tcp_relay(tox, "127.0.0.2", 33446, pub_key, nullptr);
-    assert(tcp_success);
+    tox_bootstrap(tox, "127.0.0.2", 33446, pub_key, nullptr);
+    tox_add_tcp_relay(tox, "127.0.0.2", 33446, pub_key, nullptr);
 
     tox_events_init(tox);
 
@@ -169,7 +169,7 @@ void TestBootstrap(Fuzz_Data &input)
     while (input.size > 0) {
         Tox_Err_Events_Iterate error_iterate;
         Tox_Events *events = tox_events_iterate(tox, true, &error_iterate);
-        assert(tox_events_equal(sys.sys.get(), events, events));
+        assert(tox_events_equal(null_sys.sys.get(), events, events));
         tox_dispatch_invoke(dispatch, events, tox, nullptr);
         tox_events_free(events);
         // Move the clock forward a decent amount so all the time-based checks
diff --git a/testing/fuzzing/fuzz_support.cc b/testing/fuzzing/fuzz_support.cc
index 510a6563f33..12e752abff0 100644
--- a/testing/fuzzing/fuzz_support.cc
+++ b/testing/fuzzing/fuzz_support.cc
@@ -17,17 +17,16 @@
 
 #include "../../toxcore/crypto_core.h"
 #include "../../toxcore/network.h"
-#include "../../toxcore/tox_private.h"
+#include "../../toxcore/os_network_impl.h"
+#include "../../toxcore/tox_memory_impl.h"
+#include "../../toxcore/tox_network_impl.h"
+#include "../../toxcore/tox_random_impl.h"
+#include "../../toxcore/tox_system_impl.h"
+#include "../../toxcore/tox_time_impl.h"
 #include "func_conversion.h"
 
 const bool DEBUG = false;
 
-// TODO(iphydf): Put this somewhere shared.
-struct Network_Addr {
-    struct sockaddr_storage addr;
-    size_t size;
-};
-
 System::~System() { }
 
 static int recv_common(Fuzz_Data &input, uint8_t *buf, size_t buf_len)
@@ -72,7 +71,7 @@ static void *alloc_common(Fuzz_Data &data, F func)
     return func();
 }
 
-static constexpr Memory_Funcs fuzz_memory_funcs = {
+static constexpr Tox_Memory_Funcs fuzz_memory_funcs = {
     /* .malloc = */
     ![](Fuzz_System *self, uint32_t size) {
         return alloc_common(self->data, [=]() { return std::malloc(size); });
@@ -82,14 +81,14 @@ static constexpr Memory_Funcs fuzz_memory_funcs = {
         return alloc_common(self->data, [=]() { return std::calloc(nmemb, size); });
     },
     /* .realloc = */
-    ![](Fuzz_System *self, void *ptr, uint32_t size) {
-        return alloc_common(self->data, [=]() { return std::realloc(ptr, size); });
+    ![](Fuzz_System *self, void *ptr, uint32_t nmemb, uint32_t size) {
+        return alloc_common(self->data, [=]() { return std::realloc(ptr, nmemb * size); });
     },
     /* .free = */
     ![](Fuzz_System *self, void *ptr) { std::free(ptr); },
 };
 
-static constexpr Network_Funcs fuzz_network_funcs = {
+static constexpr Tox_Network_Funcs fuzz_network_funcs = {
     /* .close = */ ![](Fuzz_System *self, int sock) { return 0; },
     /* .accept = */ ![](Fuzz_System *self, int sock) { return 1337; },
     /* .bind = */ ![](Fuzz_System *self, int sock, const Network_Addr *addr) { return 0; },
@@ -109,16 +108,14 @@ static constexpr Network_Funcs fuzz_network_funcs = {
     /* .recvfrom = */
     ![](Fuzz_System *self, int sock, uint8_t *buf, size_t len, Network_Addr *addr) {
         assert(sock == 42 || sock == 1337);
-
-        addr->addr = sockaddr_storage{};
-        // Dummy Addr
-        addr->addr.ss_family = AF_INET;
+        assert(addr != nullptr);
 
         // We want an AF_INET address with dummy values
-        sockaddr_in *addr_in = reinterpret_cast<sockaddr_in *>(&addr->addr);
-        addr_in->sin_port = htons(33446);
-        addr_in->sin_addr.s_addr = htonl(0x7f000002);  // 127.0.0.2
-        addr->size = sizeof(struct sockaddr);
+        sockaddr_in addr_in{};
+        addr_in.sin_port = htons(33446);
+        addr_in.sin_addr.s_addr = htonl(0x7f000002);  // 127.0.0.2
+
+        net_addr_set(addr, &addr_in, sizeof(addr_in));
 
         return recv_common(self->data, buf, len);
     },
@@ -147,7 +144,7 @@ static constexpr Network_Funcs fuzz_network_funcs = {
     },
 };
 
-static constexpr Random_Funcs fuzz_random_funcs = {
+static constexpr Tox_Random_Funcs fuzz_random_funcs = {
     /* .random_bytes = */
     ![](Fuzz_System *self, uint8_t *bytes, size_t length) {
         // Amount of data is limited
@@ -165,7 +162,7 @@ static constexpr Random_Funcs fuzz_random_funcs = {
     ![](Fuzz_System *self, uint32_t upper_bound) {
         uint32_t randnum = 0;
         if (upper_bound > 0) {
-            self->rng->funcs->random_bytes(
+            self->rng->funcs->bytes_callback(
                 self, reinterpret_cast<uint8_t *>(&randnum), sizeof(randnum));
             randnum %= upper_bound;
         }
@@ -173,34 +170,41 @@ static constexpr Random_Funcs fuzz_random_funcs = {
     },
 };
 
+static constexpr Tox_Time_Funcs fuzz_time_funcs = {
+    /* .monotonic = */
+    ![](Fuzz_System *self) { return self->clock; },
+};
+
 Fuzz_System::Fuzz_System(Fuzz_Data &input)
     : System{
         std::make_unique<Tox_System>(),
         std::make_unique<Memory>(Memory{&fuzz_memory_funcs, this}),
         std::make_unique<Network>(Network{&fuzz_network_funcs, this}),
         std::make_unique<Random>(Random{&fuzz_random_funcs, this}),
+        std::make_unique<Tox_Time>(Tox_Time{&fuzz_time_funcs, this}),
     }
     , data(input)
 {
-    sys->mono_time_callback = ![](Fuzz_System *self) { return self->clock; };
-    sys->mono_time_user_data = this;
     sys->mem = mem.get();
     sys->ns = ns.get();
     sys->rng = rng.get();
+    sys->tm = tm.get();
 }
 
-static constexpr Memory_Funcs null_memory_funcs = {
+static constexpr Tox_Memory_Funcs null_memory_funcs = {
     /* .malloc = */
     ![](Null_System *self, uint32_t size) { return std::malloc(size); },
     /* .calloc = */
     ![](Null_System *self, uint32_t nmemb, uint32_t size) { return std::calloc(nmemb, size); },
     /* .realloc = */
-    ![](Null_System *self, void *ptr, uint32_t size) { return std::realloc(ptr, size); },
+    ![](Null_System *self, void *ptr, uint32_t nmemb, uint32_t size) {
+        return std::realloc(ptr, nmemb * size);
+    },
     /* .free = */
     ![](Null_System *self, void *ptr) { std::free(ptr); },
 };
 
-static constexpr Network_Funcs null_network_funcs = {
+static constexpr Tox_Network_Funcs null_network_funcs = {
     /* .close = */ ![](Null_System *self, int sock) { return 0; },
     /* .accept = */ ![](Null_System *self, int sock) { return 1337; },
     /* .bind = */ ![](Null_System *self, int sock, const Network_Addr *addr) { return 0; },
@@ -248,7 +252,7 @@ static uint64_t simple_rng(uint64_t &seed)
     return seed;
 }
 
-static constexpr Random_Funcs null_random_funcs = {
+static constexpr Tox_Random_Funcs null_random_funcs = {
     /* .random_bytes = */
     ![](Null_System *self, uint8_t *bytes, size_t length) {
         for (size_t i = 0; i < length; ++i) {
@@ -264,36 +268,27 @@ static constexpr Random_Funcs null_random_funcs = {
 Null_System::Null_System()
     : System{
         std::make_unique<Tox_System>(),
-        std::make_unique<Memory>(Memory{&null_memory_funcs, this}),
-        std::make_unique<Network>(Network{&null_network_funcs, this}),
-        std::make_unique<Random>(Random{&null_random_funcs, this}),
+        std::make_unique<Tox_Memory>(Tox_Memory{&null_memory_funcs, this}),
+        std::make_unique<Tox_Network>(Tox_Network{&null_network_funcs, this}),
+        std::make_unique<Tox_Random>(Tox_Random{&null_random_funcs, this}),
+        std::make_unique<Tox_Time>(Tox_Time{&fuzz_time_funcs, this}),
     }
 {
-    sys->mono_time_callback = ![](Fuzz_System *self) { return self->clock; };
-    sys->mono_time_user_data = this;
     sys->mem = mem.get();
     sys->ns = ns.get();
     sys->rng = rng.get();
+    sys->tm = tm.get();
 }
 
-static uint16_t get_port(const Network_Addr *addr)
-{
-    if (addr->addr.ss_family == AF_INET6) {
-        return reinterpret_cast<const sockaddr_in6 *>(&addr->addr)->sin6_port;
-    } else {
-        assert(addr->addr.ss_family == AF_INET);
-        return reinterpret_cast<const sockaddr_in *>(&addr->addr)->sin_port;
-    }
-}
+static constexpr Tox_Memory_Funcs record_memory_funcs = null_memory_funcs;
 
-static constexpr Memory_Funcs record_memory_funcs = null_memory_funcs;
-
-static constexpr Network_Funcs record_network_funcs = {
+static constexpr Tox_Network_Funcs record_network_funcs = {
     /* .close = */ ![](Record_System *self, int sock) { return 0; },
     /* .accept = */ ![](Record_System *self, int sock) { return 2; },
     /* .bind = */
     ![](Record_System *self, int sock, const Network_Addr *addr) {
-        const uint16_t port = get_port(addr);
+        assert(addr != nullptr);
+        const uint16_t port = net_addr_get_port(addr);
         if (self->global_.bound.find(port) != self->global_.bound.end()) {
             errno = EADDRINUSE;
             return -1;
@@ -313,6 +308,7 @@ static constexpr Network_Funcs record_network_funcs = {
     /* .recvfrom = */
     ![](Record_System *self, int sock, uint8_t *buf, size_t len, Network_Addr *addr) {
         assert(sock == 42);
+        assert(addr != nullptr);
         if (self->recvq.empty()) {
             self->recording.push_back(0xff);
             self->recording.push_back(0xff);
@@ -327,15 +323,13 @@ static constexpr Network_Funcs record_network_funcs = {
         const size_t recvlen = std::min(len, packet.size());
         std::copy(packet.begin(), packet.end(), buf);
 
-        addr->addr = sockaddr_storage{};
-        // Dummy Addr
-        addr->addr.ss_family = AF_INET;
-
         // We want an AF_INET address with dummy values
-        sockaddr_in *addr_in = reinterpret_cast<sockaddr_in *>(&addr->addr);
-        addr_in->sin_port = from;
-        addr_in->sin_addr.s_addr = htonl(0x7f000002);  // 127.0.0.2
-        addr->size = sizeof(struct sockaddr);
+        sockaddr_in addr_in{};
+        addr_in.sin_family = AF_INET;
+        addr_in.sin_port = from;
+        addr_in.sin_addr.s_addr = htonl(0x7f000002);  // 127.0.0.2
+
+        net_addr_set(addr, &addr_in, sizeof(addr_in));
 
         assert(recvlen > 0 && recvlen <= INT_MAX);
         self->recording.push_back(recvlen >> 8);
@@ -355,7 +349,8 @@ static constexpr Network_Funcs record_network_funcs = {
     /* .sendto = */
     ![](Record_System *self, int sock, const uint8_t *buf, size_t len, const Network_Addr *addr) {
         assert(sock == 42);
-        auto backend = self->global_.bound.find(get_port(addr));
+        assert(addr != nullptr);
+        auto backend = self->global_.bound.find(net_addr_get_port(addr));
         assert(backend != self->global_.bound.end());
         backend->second->receive(self->port, buf, len);
         return static_cast<int>(len);
@@ -373,7 +368,7 @@ static constexpr Network_Funcs record_network_funcs = {
     },
 };
 
-static constexpr Random_Funcs record_random_funcs = {
+static constexpr Tox_Random_Funcs record_random_funcs = {
     /* .random_bytes = */
     ![](Record_System *self, uint8_t *bytes, size_t length) {
         for (size_t i = 0; i < length; ++i) {
@@ -386,7 +381,7 @@ static constexpr Random_Funcs record_random_funcs = {
         }
     },
     /* .random_uniform = */
-    fuzz_random_funcs.random_uniform,
+    fuzz_random_funcs.uniform_callback,
 };
 
 Record_System::Record_System(Global &global, uint64_t seed, const char *name)
@@ -395,16 +390,16 @@ Record_System::Record_System(Global &global, uint64_t seed, const char *name)
         std::make_unique<Memory>(Memory{&record_memory_funcs, this}),
         std::make_unique<Network>(Network{&record_network_funcs, this}),
         std::make_unique<Random>(Random{&record_random_funcs, this}),
+        std::make_unique<Tox_Time>(Tox_Time{&fuzz_time_funcs, this}),
     }
     , global_(global)
     , seed_(seed)
     , name_(name)
 {
-    sys->mono_time_callback = ![](Fuzz_System *self) { return self->clock; };
-    sys->mono_time_user_data = this;
     sys->mem = mem.get();
     sys->ns = ns.get();
     sys->rng = rng.get();
+    sys->tm = tm.get();
 }
 
 void Record_System::receive(uint16_t send_port, const uint8_t *buf, size_t len)
diff --git a/testing/fuzzing/fuzz_support.h b/testing/fuzzing/fuzz_support.h
index a20d85b4f2e..e52e4cc7828 100644
--- a/testing/fuzzing/fuzz_support.h
+++ b/testing/fuzzing/fuzz_support.h
@@ -117,15 +117,17 @@ void fuzz_select_target(const uint8_t *data, std::size_t size, Args &&... args)
     return fuzz_select_target(selector, input, std::forward<Args>(args)...);
 }
 
-struct Memory;
-struct Network;
-struct Random;
+struct Tox_Memory;
+struct Tox_Network;
+struct Tox_Random;
+struct Tox_Time;
 
 struct System {
     std::unique_ptr<Tox_System> sys;
-    std::unique_ptr<Memory> mem;
-    std::unique_ptr<Network> ns;
-    std::unique_ptr<Random> rng;
+    std::unique_ptr<Tox_Memory> mem;
+    std::unique_ptr<Tox_Network> ns;
+    std::unique_ptr<Tox_Random> rng;
+    std::unique_ptr<Tox_Time> tm;
 
     // Not inline because sizeof of the above 2 structs is not known everywhere.
     ~System();
diff --git a/tox.h b/tox.h
new file mode 100644
index 00000000000..64973f472f5
--- /dev/null
+++ b/tox.h
@@ -0,0 +1 @@
+#include "toxcore/tox.h"
diff --git a/toxav.h b/toxav.h
new file mode 100644
index 00000000000..25f999d9fd6
--- /dev/null
+++ b/toxav.h
@@ -0,0 +1 @@
+#include "toxav/toxav.h"
diff --git a/toxav/BUILD.bazel b/toxav/BUILD.bazel
index ca88f1334aa..c3f3423a89a 100644
--- a/toxav/BUILD.bazel
+++ b/toxav/BUILD.bazel
@@ -81,6 +81,7 @@ cc_test(
     deps = [
         ":rtp",
         "//c-toxcore/toxcore:crypto_core",
+        "//c-toxcore/toxcore:os_random",
         "@com_google_googletest//:gtest",
         "@com_google_googletest//:gtest_main",
     ],
diff --git a/toxav/rtp_test.cc b/toxav/rtp_test.cc
index b29c937ac91..24e5244804d 100644
--- a/toxav/rtp_test.cc
+++ b/toxav/rtp_test.cc
@@ -3,6 +3,7 @@
 #include <gtest/gtest.h>
 
 #include "../toxcore/crypto_core.h"
+#include "../toxcore/os_random.h"
 
 namespace {
 
@@ -29,7 +30,7 @@ RTPHeader random_header(const Random *rng)
 
 TEST(Rtp, Deserialisation)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
     RTPHeader const header = random_header(rng);
 
diff --git a/toxav/toxav.c b/toxav/toxav.c
index bdec43b504a..c9a3d1db70a 100644
--- a/toxav/toxav.c
+++ b/toxav/toxav.c
@@ -181,7 +181,7 @@ ToxAV *toxav_new(Tox *tox, Toxav_Err_New *error)
 
     av->tox = tox;
     av->m = m;
-    av->toxav_mono_time = mono_time_new(tox->sys.mem, nullptr, nullptr);
+    av->toxav_mono_time = mono_time_new(tox->sys.mem, nullptr);
     av->msi = msi_new(av->m);
 
     if (av->msi == nullptr) {
diff --git a/toxcore/BUILD.bazel b/toxcore/BUILD.bazel
index 4701cf437d3..38f693333c0 100644
--- a/toxcore/BUILD.bazel
+++ b/toxcore/BUILD.bazel
@@ -5,13 +5,22 @@ load("//tools:no_undefined.bzl", "cc_library")
 package(features = ["layering_check"])
 
 exports_files(
-    srcs = ["tox.h"],
+    srcs = [
+        "tox.h",
+        "tox_attributes.h",
+        "tox_logger.h",
+        "tox_memory.h",
+        "tox_network.h",
+        "tox_random.h",
+        "tox_system.h",
+        "tox_time.h",
+    ],
     visibility = ["//c-toxcore:__pkg__"],
 )
 
 cc_library(
-    name = "attributes",
-    hdrs = ["attributes.h"],
+    name = "tox_attributes",
+    hdrs = ["tox_attributes.h"],
     visibility = ["//c-toxcore:__subpackages__"],
 )
 
@@ -20,7 +29,163 @@ cc_library(
     srcs = ["ccompat.c"],
     hdrs = ["ccompat.h"],
     visibility = ["//c-toxcore:__subpackages__"],
-    deps = [":attributes"],
+    deps = [":tox_attributes"],
+)
+
+cc_library(
+    name = "tox_memory",
+    srcs = ["tox_memory.c"],
+    hdrs = [
+        "tox_memory.h",
+        "tox_memory_impl.h",
+    ],
+    visibility = ["//c-toxcore:__subpackages__"],
+    deps = [
+        ":ccompat",
+        ":tox_attributes",
+    ],
+)
+
+cc_library(
+    name = "tox_logger",
+    srcs = ["tox_logger.c"],
+    hdrs = [
+        "tox_logger.h",
+        "tox_logger_impl.h",
+    ],
+    visibility = ["//c-toxcore:__subpackages__"],
+    deps = [
+        ":ccompat",
+        ":tox_attributes",
+        ":tox_memory",
+    ],
+)
+
+cc_library(
+    name = "tox_network",
+    srcs = ["tox_network.c"],
+    hdrs = [
+        "tox_network.h",
+        "tox_network_impl.h",
+    ],
+    visibility = ["//c-toxcore:__subpackages__"],
+    deps = [
+        ":ccompat",
+        ":tox_attributes",
+        ":tox_memory",
+    ],
+)
+
+cc_library(
+    name = "tox_random",
+    srcs = ["tox_random.c"],
+    hdrs = [
+        "tox_random.h",
+        "tox_random_impl.h",
+    ],
+    visibility = ["//c-toxcore:__subpackages__"],
+    deps = [
+        ":ccompat",
+        ":tox_attributes",
+        ":tox_memory",
+    ],
+)
+
+cc_library(
+    name = "tox_time",
+    srcs = ["tox_time.c"],
+    hdrs = [
+        "tox_time.h",
+        "tox_time_impl.h",
+    ],
+    visibility = ["//c-toxcore:__subpackages__"],
+    deps = [
+        ":ccompat",
+        ":tox_attributes",
+        ":tox_memory",
+    ],
+)
+
+cc_library(
+    name = "tox_system",
+    srcs = ["tox_system.c"],
+    hdrs = [
+        "tox_system.h",
+        "tox_system_impl.h",
+    ],
+    visibility = ["//c-toxcore:__subpackages__"],
+    deps = [
+        ":ccompat",
+        ":tox_attributes",
+        ":tox_logger",
+        ":tox_memory",
+        ":tox_network",
+        ":tox_random",
+        ":tox_time",
+    ],
+)
+
+cc_library(
+    name = "os_logger",
+    srcs = ["os_logger.c"],
+    hdrs = ["os_logger.h"],
+    visibility = ["//c-toxcore:__subpackages__"],
+    deps = [
+        ":ccompat",
+        ":tox_logger",
+    ],
+)
+
+cc_library(
+    name = "os_memory",
+    srcs = ["os_memory.c"],
+    hdrs = ["os_memory.h"],
+    visibility = ["//c-toxcore:__subpackages__"],
+    deps = [
+        ":ccompat",
+        ":tox_memory",
+    ],
+)
+
+cc_library(
+    name = "os_network",
+    srcs = ["os_network.c"],
+    hdrs = [
+        "os_network.h",
+        "os_network_impl.h",
+    ],
+    visibility = ["//c-toxcore:__subpackages__"],
+    deps = [
+        ":ccompat",
+        ":tox_network",
+    ],
+)
+
+cc_library(
+    name = "os_random",
+    srcs = ["os_random.c"],
+    hdrs = ["os_random.h"],
+    visibility = ["//c-toxcore:__subpackages__"],
+    deps = [
+        ":ccompat",
+        ":tox_random",
+        "@libsodium",
+    ],
+)
+
+cc_library(
+    name = "os_system",
+    srcs = ["os_system.c"],
+    hdrs = ["os_system.h"],
+    visibility = ["//c-toxcore:__subpackages__"],
+    deps = [
+        ":ccompat",
+        ":os_logger",
+        ":os_memory",
+        ":os_network",
+        ":os_random",
+        ":tox_system",
+    ],
 )
 
 cc_library(
@@ -29,8 +194,9 @@ cc_library(
     hdrs = ["mem.h"],
     visibility = ["//c-toxcore:__subpackages__"],
     deps = [
-        ":attributes",
         ":ccompat",
+        ":tox_attributes",
+        ":tox_memory",
     ],
 )
 
@@ -40,6 +206,7 @@ cc_test(
     srcs = ["mem_test.cc"],
     deps = [
         ":mem",
+        ":os_memory",
         "@com_google_googletest//:gtest",
         "@com_google_googletest//:gtest_main",
     ],
@@ -57,9 +224,9 @@ cc_library(
         "//c-toxcore/toxav:__pkg__",
     ],
     deps = [
-        ":attributes",
         ":ccompat",
         ":mem",
+        ":tox_attributes",
         "@pthread",
     ],
 )
@@ -70,6 +237,7 @@ cc_test(
     srcs = ["util_test.cc"],
     deps = [
         ":crypto_core",
+        ":os_random",
         ":util",
         "@com_google_googletest//:gtest",
         "@com_google_googletest//:gtest_main",
@@ -82,8 +250,8 @@ cc_library(
     hdrs = ["bin_pack.h"],
     visibility = ["//c-toxcore:__subpackages__"],
     deps = [
-        ":attributes",
         ":ccompat",
+        ":tox_attributes",
         "//c-toxcore/third_party:cmp",
     ],
 )
@@ -94,8 +262,8 @@ cc_library(
     hdrs = ["bin_unpack.h"],
     visibility = ["//c-toxcore:__subpackages__"],
     deps = [
-        ":attributes",
         ":ccompat",
+        ":tox_attributes",
         "//c-toxcore/third_party:cmp",
     ],
 )
@@ -118,8 +286,9 @@ cc_library(
     hdrs = ["crypto_core.h"],
     visibility = ["//c-toxcore:__subpackages__"],
     deps = [
-        ":attributes",
         ":ccompat",
+        ":tox_attributes",
+        ":tox_random",
         "@libsodium",
     ],
 )
@@ -131,6 +300,7 @@ cc_test(
     flaky = True,
     deps = [
         ":crypto_core",
+        ":os_random",
         ":util",
         "@com_google_googletest//:gtest",
         "@com_google_googletest//:gtest_main",
@@ -142,8 +312,8 @@ cc_library(
     srcs = ["list.c"],
     hdrs = ["list.h"],
     deps = [
-        ":attributes",
         ":ccompat",
+        ":tox_attributes",
     ],
 )
 
@@ -169,8 +339,8 @@ cc_library(
         "//c-toxcore/toxav:__pkg__",
     ],
     deps = [
-        ":attributes",
         ":ccompat",
+        ":tox_attributes",
     ],
 )
 
@@ -196,9 +366,10 @@ cc_library(
         "//c-toxcore/toxav:__pkg__",
     ],
     deps = [
-        ":attributes",
         ":ccompat",
         ":mem",
+        ":tox_attributes",
+        ":tox_time",
         "@pthread",
     ],
 )
@@ -209,6 +380,8 @@ cc_test(
     srcs = ["mono_time_test.cc"],
     deps = [
         ":mono_time",
+        ":os_memory",
+        ":tox_time",
         "@com_google_googletest//:gtest",
         "@com_google_googletest//:gtest_main",
     ],
@@ -250,6 +423,8 @@ cc_library(
         ":logger",
         ":mem",
         ":mono_time",
+        ":os_network",
+        ":tox_network",
         ":util",
         "@libsodium",
         "@psocket",
@@ -298,6 +473,8 @@ cc_test(
     srcs = ["ping_array_test.cc"],
     deps = [
         ":mono_time",
+        ":os_memory",
+        ":os_random",
         ":ping_array",
         "@com_google_googletest//:gtest",
         "@com_google_googletest//:gtest_main",
@@ -338,7 +515,6 @@ cc_library(
     ],
     deps = [
         ":LAN_discovery",
-        ":attributes",
         ":ccompat",
         ":crypto_core",
         ":logger",
@@ -348,6 +524,7 @@ cc_library(
         ":ping_array",
         ":shared_key_cache",
         ":state",
+        ":tox_attributes",
         ":util",
     ],
 )
@@ -359,6 +536,9 @@ cc_test(
     deps = [
         ":DHT",
         ":crypto_core",
+        ":os_memory",
+        ":os_network",
+        ":os_random",
         "@com_google_googletest//:gtest",
         "@com_google_googletest//:gtest_main",
     ],
@@ -409,6 +589,8 @@ cc_fuzz_test(
     #corpus = ["//tools/toktok-fuzzer/corpus:forwarding_fuzz_test"],
     deps = [
         ":forwarding",
+        ":os_memory",
+        ":os_network",
         "//c-toxcore/testing/fuzzing:fuzz_support",
         "//c-toxcore/testing/fuzzing:fuzz_tox",
     ],
@@ -438,11 +620,11 @@ cc_library(
     hdrs = ["TCP_common.h"],
     visibility = ["//c-toxcore/auto_tests:__pkg__"],
     deps = [
-        ":attributes",
         ":ccompat",
         ":crypto_core",
         ":mem",
         ":network",
+        ":tox_attributes",
     ],
 )
 
@@ -580,6 +762,8 @@ cc_test(
     deps = [
         ":group_announce",
         ":mono_time",
+        ":os_memory",
+        ":tox_time",
         "@com_google_googletest//:gtest",
         "@com_google_googletest//:gtest_main",
     ],
@@ -607,6 +791,8 @@ cc_fuzz_test(
     #corpus = ["//tools/toktok-fuzzer/corpus:group_announce_fuzz_test"],
     deps = [
         ":group_announce",
+        ":os_memory",
+        ":tox_time",
         "//c-toxcore/testing/fuzzing:fuzz_support",
     ],
 )
@@ -698,6 +884,8 @@ cc_test(
         ":crypto_core",
         ":group_moderation",
         ":logger",
+        ":os_memory",
+        ":os_random",
         ":util",
         "@com_google_googletest//:gtest",
         "@com_google_googletest//:gtest_main",
@@ -710,6 +898,7 @@ cc_fuzz_test(
     corpus = ["//tools/toktok-fuzzer/corpus:group_moderation_fuzz_test"],
     deps = [
         ":group_moderation",
+        ":os_memory",
         "//c-toxcore/testing/fuzzing:fuzz_support",
     ],
 )
@@ -798,6 +987,9 @@ cc_library(
         ":mem",
         ":mono_time",
         ":network",
+        ":os_system",
+        ":tox_logger",
+        ":tox_system",
         "//c-toxcore/toxencryptsave:defines",
     ],
 )
@@ -808,6 +1000,7 @@ cc_test(
     srcs = ["tox_test.cc"],
     deps = [
         ":crypto_core",
+        ":os_random",
         ":tox",
         "@com_google_googletest//:gtest",
         "@com_google_googletest//:gtest_main",
@@ -820,10 +1013,10 @@ cc_library(
     hdrs = ["tox_unpack.h"],
     visibility = ["//c-toxcore:__subpackages__"],
     deps = [
-        ":attributes",
         ":bin_unpack",
         ":ccompat",
         ":tox",
+        ":tox_attributes",
     ],
 )
 
@@ -836,12 +1029,13 @@ cc_library(
     hdrs = ["tox_events.h"],
     visibility = ["//c-toxcore:__subpackages__"],
     deps = [
-        ":attributes",
         ":bin_pack",
         ":bin_unpack",
         ":ccompat",
         ":mem",
         ":tox",
+        ":tox_attributes",
+        ":tox_system",
         ":tox_unpack",
         "//c-toxcore/third_party:cmp",
     ],
@@ -853,8 +1047,10 @@ cc_test(
     srcs = ["tox_events_test.cc"],
     deps = [
         ":crypto_core",
+        ":os_system",
         ":tox",
         ":tox_events",
+        ":tox_system",
         "@com_google_googletest//:gtest",
         "@com_google_googletest//:gtest_main",
     ],
diff --git a/toxcore/DHT.c b/toxcore/DHT.c
index 1b4062cbbe4..0fc0103fe68 100644
--- a/toxcore/DHT.c
+++ b/toxcore/DHT.c
@@ -92,7 +92,7 @@ struct DHT {
     const Network *ns;
     Mono_Time *mono_time;
     const Memory *mem;
-    const Random *rng;
+    const Tox_Random *rng;
     Networking_Core *net;
 
     bool hole_punching_enabled;
@@ -275,7 +275,7 @@ const uint8_t *dht_get_shared_key_sent(DHT *dht, const uint8_t *public_key)
 
 #define CRYPTO_SIZE (1 + CRYPTO_PUBLIC_KEY_SIZE * 2 + CRYPTO_NONCE_SIZE)
 
-int create_request(const Random *rng, const uint8_t *send_public_key, const uint8_t *send_secret_key,
+int create_request(const Tox_Random *rng, const uint8_t *send_public_key, const uint8_t *send_secret_key,
                    uint8_t *packet, const uint8_t *recv_public_key,
                    const uint8_t *data, uint32_t data_length, uint8_t request_id)
 {
@@ -415,7 +415,7 @@ int pack_ip_port(const Logger *logger, uint8_t *data, uint16_t length, const IP_
     }
 }
 
-int dht_create_packet(const Memory *mem, const Random *rng,
+int dht_create_packet(const Memory *mem, const Tox_Random *rng,
                       const uint8_t public_key[CRYPTO_PUBLIC_KEY_SIZE],
                       const uint8_t *shared_key, const uint8_t type,
                       const uint8_t *plain, size_t plain_length,
@@ -2449,7 +2449,7 @@ static void do_NAT(DHT *dht)
  * @return the number of nodes.
  */
 non_null()
-static uint16_t list_nodes(const Random *rng, const Client_data *list, size_t length,
+static uint16_t list_nodes(const Tox_Random *rng, const Client_data *list, size_t length,
                            uint64_t cur_time, Node_format *nodes, uint16_t max_num)
 {
     if (max_num == 0) {
@@ -2609,7 +2609,7 @@ static int handle_LANdiscovery(void *object, const IP_Port *source, const uint8_
 
 /*----------------------------------------------------------------------------------*/
 
-DHT *new_dht(const Logger *log, const Memory *mem, const Random *rng, const Network *ns,
+DHT *new_dht(const Logger *log, const Memory *mem, const Tox_Random *rng, const Network *ns,
              Mono_Time *mono_time, Networking_Core *net,
              bool hole_punching_enabled, bool lan_discovery_enabled)
 {
diff --git a/toxcore/DHT.h b/toxcore/DHT.h
index 95f442e79fa..19bae82ce33 100644
--- a/toxcore/DHT.h
+++ b/toxcore/DHT.h
@@ -11,7 +11,7 @@
 
 #include <stdbool.h>
 
-#include "attributes.h"
+#include "tox_attributes.h"
 #include "crypto_core.h"
 #include "logger.h"
 #include "mem.h"
@@ -113,7 +113,7 @@ extern "C" {
  * @return the length of the created packet on success.
  */
 non_null()
-int create_request(const Random *rng, const uint8_t *send_public_key, const uint8_t *send_secret_key,
+int create_request(const Tox_Random *rng, const uint8_t *send_public_key, const uint8_t *send_secret_key,
                    uint8_t *packet, const uint8_t *recv_public_key,
                    const uint8_t *data, uint32_t data_length, uint8_t request_id);
 
@@ -220,7 +220,7 @@ int pack_ip_port(const Logger *logger, uint8_t *data, uint16_t length, const IP_
  * @retval -1 on failure.
  */
 non_null()
-int dht_create_packet(const Memory *mem, const Random *rng,
+int dht_create_packet(const Memory *mem, const Tox_Random *rng,
                       const uint8_t public_key[CRYPTO_PUBLIC_KEY_SIZE],
                       const uint8_t *shared_key, const uint8_t type,
                       const uint8_t *plain, size_t plain_length,
@@ -495,7 +495,7 @@ int dht_load(DHT *dht, const uint8_t *data, uint32_t length);
 
 /** Initialize DHT. */
 non_null()
-DHT *new_dht(const Logger *log, const Memory *mem, const Random *rng, const Network *ns,
+DHT *new_dht(const Logger *log, const Memory *mem, const Tox_Random *rng, const Network *ns,
              Mono_Time *mono_time, Networking_Core *net, bool hole_punching_enabled, bool lan_discovery_enabled);
 
 nullable(1)
diff --git a/toxcore/DHT_test.cc b/toxcore/DHT_test.cc
index 84d3b9820a1..0f158b6dbc5 100644
--- a/toxcore/DHT_test.cc
+++ b/toxcore/DHT_test.cc
@@ -6,6 +6,9 @@
 #include <array>
 
 #include "crypto_core.h"
+#include "os_memory.h"
+#include "os_network.h"
+#include "os_random.h"
 
 namespace {
 
@@ -36,7 +39,7 @@ PublicKey random_pk(const Random *rng)
 
 TEST(IdClosest, IdenticalKeysAreSameDistance)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
 
     PublicKey pk0 = random_pk(rng);
@@ -48,7 +51,7 @@ TEST(IdClosest, IdenticalKeysAreSameDistance)
 
 TEST(IdClosest, DistanceIsCommutative)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
 
     for (uint32_t i = 0; i < 100; ++i) {
@@ -130,7 +133,7 @@ TEST(AddToList, OverridesKeysWithCloserKeys)
 
 TEST(Request, CreateAndParse)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
 
     // Peers.
@@ -187,12 +190,12 @@ TEST(Request, CreateAndParse)
 
 TEST(AnnounceNodes, SetAndTest)
 {
-    const Random *rng = system_random();
-    const Network *ns = system_network();
-    const Memory *mem = system_memory();
+    const Random *rng = os_random();
+    const Network *ns = os_network();
+    const Memory *mem = os_memory();
 
     Logger *log = logger_new();
-    Mono_Time *mono_time = mono_time_new(mem, nullptr, nullptr);
+    Mono_Time *mono_time = mono_time_new(mem, nullptr);
     Networking_Core *net = new_networking_no_udp(log, mem, ns);
     DHT *dht = new_dht(log, mem, rng, ns, mono_time, net, true, true);
     ASSERT_NE(dht, nullptr);
diff --git a/toxcore/Makefile.inc b/toxcore/Makefile.inc
index 70df82b39e6..cc132cafa07 100644
--- a/toxcore/Makefile.inc
+++ b/toxcore/Makefile.inc
@@ -7,19 +7,26 @@ libtoxcore_la_includedir = $(includedir)/tox
 
 libtoxcore_la_SOURCES = ../third_party/cmp/cmp.c \
                         ../third_party/cmp/cmp.h \
-                        ../toxcore/attributes.h \
+                        ../toxcore/announce.c \
+                        ../toxcore/announce.h \
                         ../toxcore/bin_pack.c \
                         ../toxcore/bin_pack.h \
                         ../toxcore/bin_unpack.c \
                         ../toxcore/bin_unpack.h \
                         ../toxcore/ccompat.c \
                         ../toxcore/ccompat.h \
+                        ../toxcore/crypto_core.c \
+                        ../toxcore/crypto_core.h \
+                        ../toxcore/DHT.c \
+                        ../toxcore/DHT.h \
                         ../toxcore/events/conference_connected.c \
                         ../toxcore/events/conference_invite.c \
                         ../toxcore/events/conference_message.c \
                         ../toxcore/events/conference_peer_list_changed.c \
                         ../toxcore/events/conference_peer_name.c \
                         ../toxcore/events/conference_title.c \
+                        ../toxcore/events/events_alloc.c \
+                        ../toxcore/events/events_alloc.h \
                         ../toxcore/events/file_chunk_request.c \
                         ../toxcore/events/file_recv.c \
                         ../toxcore/events/file_recv_chunk.c \
@@ -34,90 +41,112 @@ libtoxcore_la_SOURCES = ../third_party/cmp/cmp.c \
                         ../toxcore/events/friend_status.c \
                         ../toxcore/events/friend_status_message.c \
                         ../toxcore/events/friend_typing.c \
-                        ../toxcore/events/events_alloc.c \
-                        ../toxcore/events/events_alloc.h \
                         ../toxcore/events/self_connection_status.c \
-                        ../toxcore/DHT.h \
-                        ../toxcore/DHT.c \
-                        ../toxcore/mem.h \
-                        ../toxcore/mem.c \
-                        ../toxcore/mono_time.h \
-                        ../toxcore/mono_time.c \
-                        ../toxcore/network.h \
-                        ../toxcore/network.c \
-                        ../toxcore/crypto_core.h \
-                        ../toxcore/crypto_core.c \
-                        ../toxcore/timed_auth.h \
-                        ../toxcore/timed_auth.c \
-                        ../toxcore/ping_array.h \
-                        ../toxcore/ping_array.c \
-                        ../toxcore/net_crypto.h \
-                        ../toxcore/net_crypto.c \
-                        ../toxcore/friend_requests.h \
-                        ../toxcore/friend_requests.c \
-                        ../toxcore/LAN_discovery.h \
-                        ../toxcore/LAN_discovery.c \
-                        ../toxcore/friend_connection.h \
+                        ../toxcore/forwarding.c \
+                        ../toxcore/forwarding.h \
                         ../toxcore/friend_connection.c \
-                        ../toxcore/Messenger.h \
-                        ../toxcore/Messenger.c \
-                        ../toxcore/ping.h \
-                        ../toxcore/ping.c \
-                        ../toxcore/shared_key_cache.h \
-                        ../toxcore/shared_key_cache.c \
-                        ../toxcore/state.h \
-                        ../toxcore/state.c \
-                        ../toxcore/tox.h \
-                        ../toxcore/tox.c \
-                        ../toxcore/tox_dispatch.h \
-                        ../toxcore/tox_dispatch.c \
-                        ../toxcore/tox_events.h \
-                        ../toxcore/tox_events.c \
-                        ../toxcore/tox_unpack.h \
-                        ../toxcore/tox_unpack.c \
-                        ../toxcore/tox_private.c \
-                        ../toxcore/tox_private.h \
-                        ../toxcore/tox_struct.h \
-                        ../toxcore/tox_api.c \
-                        ../toxcore/util.h \
-                        ../toxcore/util.c \
-                        ../toxcore/group.h \
-                        ../toxcore/group.c \
-                        ../toxcore/group_announce.h \
+                        ../toxcore/friend_connection.h \
+                        ../toxcore/friend_requests.c \
+                        ../toxcore/friend_requests.h \
                         ../toxcore/group_announce.c \
-                        ../toxcore/group_onion_announce.c \
-                        ../toxcore/group_onion_announce.h \
-                        ../toxcore/group_chats.h \
+                        ../toxcore/group_announce.h \
+                        ../toxcore/group.c \
                         ../toxcore/group_chats.c \
+                        ../toxcore/group_chats.h \
                         ../toxcore/group_common.h \
                         ../toxcore/group_connection.c \
                         ../toxcore/group_connection.h \
-                        ../toxcore/group_pack.c \
-                        ../toxcore/group_pack.h \
+                        ../toxcore/group.h \
                         ../toxcore/group_moderation.c \
                         ../toxcore/group_moderation.h \
-                        ../toxcore/onion.h \
-                        ../toxcore/onion.c \
-                        ../toxcore/logger.h \
+                        ../toxcore/group_onion_announce.c \
+                        ../toxcore/group_onion_announce.h \
+                        ../toxcore/group_pack.c \
+                        ../toxcore/group_pack.h \
+                        ../toxcore/LAN_discovery.c \
+                        ../toxcore/LAN_discovery.h \
+                        ../toxcore/list.c \
+                        ../toxcore/list.h \
                         ../toxcore/logger.c \
-                        ../toxcore/onion_announce.h \
+                        ../toxcore/logger.h \
+                        ../toxcore/mem.c \
+                        ../toxcore/mem.h \
+                        ../toxcore/Messenger.c \
+                        ../toxcore/Messenger.h \
+                        ../toxcore/mono_time.c \
+                        ../toxcore/mono_time.h \
+                        ../toxcore/net_crypto.c \
+                        ../toxcore/net_crypto.h \
+                        ../toxcore/network.c \
+                        ../toxcore/network.h \
                         ../toxcore/onion_announce.c \
-                        ../toxcore/onion_client.h \
+                        ../toxcore/onion_announce.h \
+                        ../toxcore/onion.c \
                         ../toxcore/onion_client.c \
-                        ../toxcore/announce.h \
-                        ../toxcore/announce.c \
-                        ../toxcore/forwarding.h \
-                        ../toxcore/forwarding.c \
-                        ../toxcore/TCP_client.h \
+                        ../toxcore/onion_client.h \
+                        ../toxcore/onion.h \
+                        ../toxcore/os_logger.c \
+                        ../toxcore/os_logger.h \
+                        ../toxcore/os_memory.c \
+                        ../toxcore/os_memory.h \
+                        ../toxcore/os_network.c \
+                        ../toxcore/os_network.h \
+                        ../toxcore/os_network_impl.h \
+                        ../toxcore/os_random.c \
+                        ../toxcore/os_random.h \
+                        ../toxcore/os_system.c \
+                        ../toxcore/os_system.h \
+                        ../toxcore/ping_array.c \
+                        ../toxcore/ping_array.h \
+                        ../toxcore/ping.c \
+                        ../toxcore/ping.h \
+                        ../toxcore/shared_key_cache.c \
+                        ../toxcore/shared_key_cache.h \
+                        ../toxcore/state.c \
+                        ../toxcore/state.h \
                         ../toxcore/TCP_client.c \
-                        ../toxcore/TCP_common.h \
+                        ../toxcore/TCP_client.h \
                         ../toxcore/TCP_common.c \
-                        ../toxcore/TCP_server.h \
-                        ../toxcore/TCP_server.c \
-                        ../toxcore/TCP_connection.h \
+                        ../toxcore/TCP_common.h \
                         ../toxcore/TCP_connection.c \
-                        ../toxcore/list.c \
-                        ../toxcore/list.h
+                        ../toxcore/TCP_connection.h \
+                        ../toxcore/TCP_server.c \
+                        ../toxcore/TCP_server.h \
+                        ../toxcore/timed_auth.c \
+                        ../toxcore/timed_auth.h \
+                        ../toxcore/tox_api.c \
+                        ../toxcore/tox_attributes.h \
+                        ../toxcore/tox.c \
+                        ../toxcore/tox_dispatch.c \
+                        ../toxcore/tox_dispatch.h \
+                        ../toxcore/tox_events.c \
+                        ../toxcore/tox_events.h \
+                        ../toxcore/tox.h \
+                        ../toxcore/tox_logger.c \
+                        ../toxcore/tox_logger.h \
+                        ../toxcore/tox_logger_impl.h \
+                        ../toxcore/tox_memory.c \
+                        ../toxcore/tox_memory.h \
+                        ../toxcore/tox_memory_impl.h \
+                        ../toxcore/tox_network.c \
+                        ../toxcore/tox_network.h \
+                        ../toxcore/tox_network_impl.h \
+                        ../toxcore/tox_private.c \
+                        ../toxcore/tox_private.h \
+                        ../toxcore/tox_random.c \
+                        ../toxcore/tox_random.h \
+                        ../toxcore/tox_random_impl.h \
+                        ../toxcore/tox_struct.h \
+                        ../toxcore/tox_system.c \
+                        ../toxcore/tox_system.h \
+                        ../toxcore/tox_system_impl.h \
+                        ../toxcore/tox_time.c \
+                        ../toxcore/tox_time.h \
+                        ../toxcore/tox_time_impl.h \
+                        ../toxcore/tox_unpack.c \
+                        ../toxcore/tox_unpack.h \
+                        ../toxcore/util.c \
+                        ../toxcore/util.h
 
 libtoxcore_la_CFLAGS =  -I$(top_srcdir) \
                         -I$(top_srcdir)/toxcore \
diff --git a/toxcore/Messenger.c b/toxcore/Messenger.c
index f5ae68a0f21..4338d7fa672 100644
--- a/toxcore/Messenger.c
+++ b/toxcore/Messenger.c
@@ -3503,7 +3503,7 @@ static void m_handle_friend_request(
  *
  * if error is not NULL it will be set to one of the values in the enum above.
  */
-Messenger *new_messenger(Mono_Time *mono_time, const Memory *mem, const Random *rng, const Network *ns,
+Messenger *new_messenger(Mono_Time *mono_time, const Memory *mem, const Tox_Random *rng, const Network *ns,
                          Messenger_Options *options, Messenger_Error *error)
 {
     if (options == nullptr) {
diff --git a/toxcore/Messenger.h b/toxcore/Messenger.h
index cabb2af89d8..e4a42b952c4 100644
--- a/toxcore/Messenger.h
+++ b/toxcore/Messenger.h
@@ -246,7 +246,7 @@ struct Messenger {
     Logger *log;
     Mono_Time *mono_time;
     const Memory *mem;
-    const Random *rng;
+    const Tox_Random *rng;
     const Network *ns;
 
     Networking_Core *net;
@@ -814,7 +814,7 @@ typedef enum Messenger_Error {
  * if error is not NULL it will be set to one of the values in the enum above.
  */
 non_null()
-Messenger *new_messenger(Mono_Time *mono_time, const Memory *mem, const Random *rng, const Network *ns,
+Messenger *new_messenger(Mono_Time *mono_time, const Memory *mem, const Tox_Random *rng, const Network *ns,
                          Messenger_Options *options, Messenger_Error *error);
 
 /** @brief Run this before closing shop.
diff --git a/toxcore/TCP_client.c b/toxcore/TCP_client.c
index 5aec2337f5b..ac1338e737d 100644
--- a/toxcore/TCP_client.c
+++ b/toxcore/TCP_client.c
@@ -571,7 +571,7 @@ void forwarding_handler(TCP_Client_Connection *con, forwarded_response_cb *forwa
 
 /** Create new TCP connection to ip_port/public_key */
 TCP_Client_Connection *new_TCP_connection(
-        const Logger *logger, const Memory *mem, const Mono_Time *mono_time, const Random *rng, const Network *ns,
+        const Logger *logger, const Memory *mem, const Mono_Time *mono_time, const Tox_Random *rng, const Network *ns,
         const IP_Port *ip_port, const uint8_t *public_key, const uint8_t *self_public_key, const uint8_t *self_secret_key,
         const TCP_Proxy_Info *proxy_info)
 {
diff --git a/toxcore/TCP_client.h b/toxcore/TCP_client.h
index b020aaad91a..8b0c4bc2c5b 100644
--- a/toxcore/TCP_client.h
+++ b/toxcore/TCP_client.h
@@ -59,7 +59,7 @@ void tcp_con_set_custom_uint(TCP_Client_Connection *con, uint32_t value);
 /** Create new TCP connection to ip_port/public_key */
 non_null(1, 2, 3, 4, 5, 6, 7, 8, 9) nullable(10)
 TCP_Client_Connection *new_TCP_connection(
-        const Logger *logger, const Memory *mem, const Mono_Time *mono_time, const Random *rng, const Network *ns,
+        const Logger *logger, const Memory *mem, const Mono_Time *mono_time, const Tox_Random *rng, const Network *ns,
         const IP_Port *ip_port, const uint8_t *public_key, const uint8_t *self_public_key, const uint8_t *self_secret_key,
         const TCP_Proxy_Info *proxy_info);
 
diff --git a/toxcore/TCP_common.h b/toxcore/TCP_common.h
index 44dc2e71e0d..4ac024c824c 100644
--- a/toxcore/TCP_common.h
+++ b/toxcore/TCP_common.h
@@ -65,7 +65,7 @@ void wipe_priority_list(const Memory *mem, TCP_Priority_List *p);
 
 typedef struct TCP_Connection {
     const Memory *mem;
-    const Random *rng;
+    const Tox_Random *rng;
     const Network *ns;
     Socket sock;
     IP_Port ip_port;  // for debugging.
diff --git a/toxcore/TCP_connection.c b/toxcore/TCP_connection.c
index 2c75e74ea5f..5f36acf46b0 100644
--- a/toxcore/TCP_connection.c
+++ b/toxcore/TCP_connection.c
@@ -20,7 +20,7 @@
 struct TCP_Connections {
     const Logger *logger;
     const Memory *mem;
-    const Random *rng;
+    const Tox_Random *rng;
     Mono_Time *mono_time;
     const Network *ns;
     DHT *dht;
@@ -1585,7 +1585,7 @@ int set_tcp_onion_status(TCP_Connections *tcp_c, bool status)
  *
  * Returns NULL on failure.
  */
-TCP_Connections *new_tcp_connections(const Logger *logger, const Memory *mem, const Random *rng, const Network *ns,
+TCP_Connections *new_tcp_connections(const Logger *logger, const Memory *mem, const Tox_Random *rng, const Network *ns,
                                      Mono_Time *mono_time, const uint8_t *secret_key, const TCP_Proxy_Info *proxy_info)
 {
     assert(logger != nullptr);
diff --git a/toxcore/TCP_connection.h b/toxcore/TCP_connection.h
index f01e7054459..3c75cae7161 100644
--- a/toxcore/TCP_connection.h
+++ b/toxcore/TCP_connection.h
@@ -298,7 +298,7 @@ uint32_t tcp_copy_connected_relays_index(const TCP_Connections *tcp_c, Node_form
  * Returns NULL on failure.
  */
 non_null()
-TCP_Connections *new_tcp_connections(const Logger *logger, const Memory *mem, const Random *rng, const Network *ns,
+TCP_Connections *new_tcp_connections(const Logger *logger, const Memory *mem, const Tox_Random *rng, const Network *ns,
                                      Mono_Time *mono_time, const uint8_t *secret_key, const TCP_Proxy_Info *proxy_info);
 
 non_null()
diff --git a/toxcore/TCP_server.c b/toxcore/TCP_server.c
index 80a1f0165aa..a87b77dc5ae 100644
--- a/toxcore/TCP_server.c
+++ b/toxcore/TCP_server.c
@@ -59,7 +59,7 @@ typedef struct TCP_Secure_Connection {
 struct TCP_Server {
     const Logger *logger;
     const Memory *mem;
-    const Random *rng;
+    const Tox_Random *rng;
     const Network *ns;
     Onion *onion;
     Forwarding *forwarding;
@@ -903,7 +903,7 @@ static int accept_connection(TCP_Server *tcp_server, Socket sock)
 }
 
 non_null()
-static Socket new_listening_TCP_socket(const Logger *logger, const Network *ns, Family family, uint16_t port)
+static Socket new_listening_TCP_socket(const Logger *logger, const Network *ns, const Memory *mem, Family family, uint16_t port)
 {
     const Socket sock = net_socket(ns, family, TOX_SOCK_STREAM, TOX_PROTO_TCP);
 
@@ -922,7 +922,7 @@ static Socket new_listening_TCP_socket(const Logger *logger, const Network *ns,
         ok = set_socket_reuseaddr(ns, sock);
     }
 
-    ok = ok && bind_to_port(ns, sock, family, port) && (net_listen(ns, sock, TCP_MAX_BACKLOG) == 0);
+    ok = ok && bind_to_port(ns, mem, sock, family, port) && (net_listen(ns, sock, TCP_MAX_BACKLOG) == 0);
 
     if (!ok) {
         char *const error = net_new_strerror(net_error());
@@ -937,7 +937,7 @@ static Socket new_listening_TCP_socket(const Logger *logger, const Network *ns,
     return sock;
 }
 
-TCP_Server *new_TCP_server(const Logger *logger, const Memory *mem, const Random *rng, const Network *ns,
+TCP_Server *new_TCP_server(const Logger *logger, const Memory *mem, const Tox_Random *rng, const Network *ns,
                            bool ipv6_enabled, uint16_t num_sockets,
                            const uint16_t *ports, const uint8_t *secret_key, Onion *onion, Forwarding *forwarding)
 {
@@ -986,7 +986,7 @@ TCP_Server *new_TCP_server(const Logger *logger, const Memory *mem, const Random
     const Family family = ipv6_enabled ? net_family_ipv6() : net_family_ipv4();
 
     for (uint32_t i = 0; i < num_sockets; ++i) {
-        const Socket sock = new_listening_TCP_socket(logger, ns, family, ports[i]);
+        const Socket sock = new_listening_TCP_socket(logger, ns, mem, family, ports[i]);
 
         if (!sock_valid(sock)) {
             continue;
diff --git a/toxcore/TCP_server.h b/toxcore/TCP_server.h
index 090e821607d..5ec2f4f32c7 100644
--- a/toxcore/TCP_server.h
+++ b/toxcore/TCP_server.h
@@ -35,7 +35,7 @@ size_t tcp_server_listen_count(const TCP_Server *tcp_server);
 
 /** Create new TCP server instance. */
 non_null(1, 2, 3, 4, 7, 8) nullable(9, 10)
-TCP_Server *new_TCP_server(const Logger *logger, const Memory *mem, const Random *rng, const Network *ns,
+TCP_Server *new_TCP_server(const Logger *logger, const Memory *mem, const Tox_Random *rng, const Network *ns,
                            bool ipv6_enabled, uint16_t num_sockets, const uint16_t *ports,
                            const uint8_t *secret_key, Onion *onion, Forwarding *forwarding);
 
diff --git a/toxcore/announce.c b/toxcore/announce.c
index fbbb2350c60..5a33a7972cc 100644
--- a/toxcore/announce.c
+++ b/toxcore/announce.c
@@ -51,7 +51,7 @@ typedef struct Announce_Entry {
 struct Announcements {
     const Logger *log;
     const Memory *mem;
-    const Random *rng;
+    const Tox_Random *rng;
     Forwarding *forwarding;
     const Mono_Time *mono_time;
     DHT *dht;
@@ -637,7 +637,7 @@ static int handle_dht_announce_request(void *object, const IP_Port *source,
     return sendpacket(announce->net, source, reply, len) == len ? 0 : -1;
 }
 
-Announcements *new_announcements(const Logger *log, const Memory *mem, const Random *rng, const Mono_Time *mono_time,
+Announcements *new_announcements(const Logger *log, const Memory *mem, const Tox_Random *rng, const Mono_Time *mono_time,
                                  Forwarding *forwarding)
 {
     if (log == nullptr || mono_time == nullptr || forwarding == nullptr) {
diff --git a/toxcore/announce.h b/toxcore/announce.h
index bbd7a72b452..e3e1d22b80d 100644
--- a/toxcore/announce.h
+++ b/toxcore/announce.h
@@ -16,7 +16,7 @@ uint8_t announce_response_of_request_type(uint8_t request_type);
 typedef struct Announcements Announcements;
 
 non_null()
-Announcements *new_announcements(const Logger *log, const Memory *mem, const Random *rng, const Mono_Time *mono_time,
+Announcements *new_announcements(const Logger *log, const Memory *mem, const Tox_Random *rng, const Mono_Time *mono_time,
                                  Forwarding *forwarding);
 
 /**
diff --git a/toxcore/bin_pack.h b/toxcore/bin_pack.h
index 51646c088a5..f38ab5f0331 100644
--- a/toxcore/bin_pack.h
+++ b/toxcore/bin_pack.h
@@ -7,7 +7,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include "attributes.h"
+#include "tox_attributes.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/toxcore/bin_unpack.h b/toxcore/bin_unpack.h
index bd4d8785c1f..a1b73b3c9a8 100644
--- a/toxcore/bin_unpack.h
+++ b/toxcore/bin_unpack.h
@@ -8,7 +8,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include "attributes.h"
+#include "tox_attributes.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/toxcore/ccompat.h b/toxcore/ccompat.h
index 9ea6739a7d3..05525ef6691 100644
--- a/toxcore/ccompat.h
+++ b/toxcore/ccompat.h
@@ -10,7 +10,7 @@
 
 #include <stddef.h>  // NULL, size_t
 
-#include "attributes.h"
+#include "tox_attributes.h"
 
 //!TOKSTYLE-
 
diff --git a/toxcore/crypto_core.c b/toxcore/crypto_core.c
index 14025252c41..f8fbb4eb1bd 100644
--- a/toxcore/crypto_core.c
+++ b/toxcore/crypto_core.c
@@ -29,6 +29,7 @@
 #endif
 
 #include "ccompat.h"
+#include "tox_random_impl.h"
 
 #ifndef crypto_box_MACBYTES
 #define crypto_box_MACBYTES (crypto_box_ZEROBYTES - crypto_box_BOXZEROBYTES)
@@ -245,7 +246,7 @@ uint64_t random_u64(const Random *rng)
 
 uint32_t random_range_u32(const Random *rng, uint32_t upper_bound)
 {
-    return rng->funcs->random_uniform(rng->obj, upper_bound);
+    return tox_random_uniform(rng, upper_bound);
 }
 
 bool crypto_signature_create(uint8_t *signature, const uint8_t *message, uint64_t message_length,
@@ -530,53 +531,7 @@ void crypto_sha512(uint8_t *hash, const uint8_t *data, size_t length)
 #endif
 }
 
-non_null()
-static void sys_random_bytes(void *obj, uint8_t *bytes, size_t length)
-{
-    randombytes(bytes, length);
-}
-
-non_null()
-static uint32_t sys_random_uniform(void *obj, uint32_t upper_bound)
-{
-#ifdef VANILLA_NACL
-    if (upper_bound == 0) {
-        return 0;
-    }
-
-    uint32_t randnum;
-    sys_random_bytes(obj, (uint8_t *)&randnum, sizeof(randnum));
-    return randnum % upper_bound;
-#else
-    return randombytes_uniform(upper_bound);
-#endif
-}
-
-static const Random_Funcs system_random_funcs = {
-    sys_random_bytes,
-    sys_random_uniform,
-};
-
-static const Random system_random_obj = {&system_random_funcs};
-
-const Random *system_random(void)
-{
-#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
-    if ((true)) {
-        return nullptr;
-    }
-#endif
-#ifndef VANILLA_NACL
-    // It is safe to call this function more than once and from different
-    // threads -- subsequent calls won't have any effects.
-    if (sodium_init() == -1) {
-        return nullptr;
-    }
-#endif
-    return &system_random_obj;
-}
-
 void random_bytes(const Random *rng, uint8_t *bytes, size_t length)
 {
-    rng->funcs->random_bytes(rng->obj, bytes, length);
+    tox_random_bytes(rng, bytes, length);
 }
diff --git a/toxcore/crypto_core.h b/toxcore/crypto_core.h
index 3b9f27d677c..5e6c6a1d406 100644
--- a/toxcore/crypto_core.h
+++ b/toxcore/crypto_core.h
@@ -13,7 +13,8 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#include "attributes.h"
+#include "tox_attributes.h"
+#include "tox_random.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -75,21 +76,6 @@ extern "C" {
  */
 #define CRYPTO_SHA512_SIZE             64
 
-typedef void crypto_random_bytes_cb(void *obj, uint8_t *bytes, size_t length);
-typedef uint32_t crypto_random_uniform_cb(void *obj, uint32_t upper_bound);
-
-typedef struct Random_Funcs {
-    crypto_random_bytes_cb *random_bytes;
-    crypto_random_uniform_cb *random_uniform;
-} Random_Funcs;
-
-typedef struct Random {
-    const Random_Funcs *funcs;
-    void *obj;
-} Random;
-
-const Random *system_random(void);
-
 /**
  * @brief The number of bytes in an encryption public key used by DHT group chats.
  */
@@ -208,6 +194,8 @@ bool crypto_sha512_eq(const uint8_t *cksum1, const uint8_t *cksum2);
 non_null()
 bool crypto_sha256_eq(const uint8_t *cksum1, const uint8_t *cksum2);
 
+typedef Tox_Random Random;
+
 /**
  * @brief Return a random 8 bit integer.
  */
diff --git a/toxcore/crypto_core_test.cc b/toxcore/crypto_core_test.cc
index 4f2a9f3085b..bde7ec7bac8 100644
--- a/toxcore/crypto_core_test.cc
+++ b/toxcore/crypto_core_test.cc
@@ -6,6 +6,7 @@
 #include <array>
 #include <vector>
 
+#include "os_random.h"
 #include "util.h"
 
 namespace {
@@ -52,7 +53,7 @@ TEST(CryptoCore, IncrementNonceNumber)
 
 TEST(CryptoCore, Signatures)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
 
     ExtPublicKey pk;
@@ -76,7 +77,7 @@ TEST(CryptoCore, Signatures)
 
 TEST(CryptoCore, Hmac)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
 
     HmacKey sk;
diff --git a/toxcore/events/events_alloc.h b/toxcore/events/events_alloc.h
index 6c5a7abd4f7..06a24942763 100644
--- a/toxcore/events/events_alloc.h
+++ b/toxcore/events/events_alloc.h
@@ -5,7 +5,7 @@
 #ifndef C_TOXCORE_TOXCORE_TOX_EVENTS_INTERNAL_H
 #define C_TOXCORE_TOXCORE_TOX_EVENTS_INTERNAL_H
 
-#include "../attributes.h"
+#include "../tox_attributes.h"
 #include "../bin_pack.h"
 #include "../bin_unpack.h"
 #include "../tox_events.h"
diff --git a/toxcore/forwarding.c b/toxcore/forwarding.c
index 5e885abd211..a4812a72366 100644
--- a/toxcore/forwarding.c
+++ b/toxcore/forwarding.c
@@ -14,7 +14,7 @@
 
 struct Forwarding {
     const Logger *log;
-    const Random *rng;
+    const Tox_Random *rng;
     DHT *dht;
     const Mono_Time *mono_time;
     Networking_Core *net;
@@ -352,7 +352,7 @@ void set_callback_forward_reply(Forwarding *forwarding, forward_reply_cb *functi
     forwarding->forward_reply_callback_object = object;
 }
 
-Forwarding *new_forwarding(const Logger *log, const Random *rng, const Mono_Time *mono_time, DHT *dht)
+Forwarding *new_forwarding(const Logger *log, const Tox_Random *rng, const Mono_Time *mono_time, DHT *dht)
 {
     if (log == nullptr || mono_time == nullptr || dht == nullptr) {
         return nullptr;
diff --git a/toxcore/forwarding.h b/toxcore/forwarding.h
index 36ce8ad8943..168cfc7bda6 100644
--- a/toxcore/forwarding.h
+++ b/toxcore/forwarding.h
@@ -113,7 +113,7 @@ non_null(1) nullable(2, 3)
 void set_callback_forward_reply(Forwarding *forwarding, forward_reply_cb *function, void *object);
 
 non_null()
-Forwarding *new_forwarding(const Logger *log, const Random *rng, const Mono_Time *mono_time, DHT *dht);
+Forwarding *new_forwarding(const Logger *log, const Tox_Random *rng, const Mono_Time *mono_time, DHT *dht);
 
 nullable(1)
 void kill_forwarding(Forwarding *forwarding);
diff --git a/toxcore/forwarding_fuzz_test.cc b/toxcore/forwarding_fuzz_test.cc
index ce263f1e6fd..a6c5581aa51 100644
--- a/toxcore/forwarding_fuzz_test.cc
+++ b/toxcore/forwarding_fuzz_test.cc
@@ -5,14 +5,16 @@
 
 #include "../testing/fuzzing/fuzz_support.h"
 #include "../testing/fuzzing/fuzz_tox.h"
+#include "os_memory.h"
+#include "os_network.h"
 
 namespace {
 
 void TestSendForwardRequest(Fuzz_Data &input)
 {
-    const Network *ns = system_network();  // TODO(iphydf): fuzz_network
+    const Network *ns = os_network();  // TODO(iphydf): fuzz_network
     assert(ns != nullptr);
-    const Memory *mem = system_memory();  // TODO(iphydf): fuzz_memory
+    const Memory *mem = os_memory();  // TODO(iphydf): fuzz_memory
     assert(mem != nullptr);
 
     with<Logger>{} >> with<Networking_Core>{input, ns, mem} >> [&input](Ptr<Networking_Core> net) {
@@ -29,9 +31,9 @@ void TestSendForwardRequest(Fuzz_Data &input)
 
 void TestForwardReply(Fuzz_Data &input)
 {
-    const Network *ns = system_network();  // TODO(iphydf): fuzz_network
+    const Network *ns = os_network();  // TODO(iphydf): fuzz_network
     assert(ns != nullptr);
-    const Memory *mem = system_memory();  // TODO(iphydf): fuzz_memory
+    const Memory *mem = os_memory();  // TODO(iphydf): fuzz_memory
     assert(mem != nullptr);
 
     with<Logger>{} >> with<Networking_Core>{input, ns, mem} >> [&input](Ptr<Networking_Core> net) {
diff --git a/toxcore/group.c b/toxcore/group.c
index 0e851b1e348..7b02a056a77 100644
--- a/toxcore/group.c
+++ b/toxcore/group.c
@@ -1309,13 +1309,13 @@ static void remove_connection_reason(Group_Chats *g_c, Group_c *g, uint16_t i, u
 
 /** @brief Creates a new groupchat and puts it in the chats array.
  *
- * @param rng Random number generator used for generating the group ID.
+ * @param rng Tox_Random number generator used for generating the group ID.
  * @param type is one of `GROUPCHAT_TYPE_*`
  *
  * @return group number on success.
  * @retval -1 on failure.
  */
-int add_groupchat(Group_Chats *g_c, const Random *rng, uint8_t type)
+int add_groupchat(Group_Chats *g_c, const Tox_Random *rng, uint8_t type)
 {
     const int32_t groupnumber = create_group_chat(g_c);
 
diff --git a/toxcore/group.h b/toxcore/group.h
index e6f6c447333..cdc3a6d6a1e 100644
--- a/toxcore/group.h
+++ b/toxcore/group.h
@@ -93,14 +93,14 @@ void g_callback_peer_list_changed(Group_Chats *g_c, peer_list_changed_cb *functi
 
 /** @brief Creates a new groupchat and puts it in the chats array.
  *
- * @param rng Random number generator used for generating the group ID.
+ * @param rng Tox_Random number generator used for generating the group ID.
  * @param type is one of `GROUPCHAT_TYPE_*`
  *
  * @return group number on success.
  * @retval -1 on failure.
  */
 non_null()
-int add_groupchat(Group_Chats *g_c, const Random *rng, uint8_t type);
+int add_groupchat(Group_Chats *g_c, const Tox_Random *rng, uint8_t type);
 
 /** @brief Delete a groupchat from the chats array, informing the group first as
  * appropriate.
diff --git a/toxcore/group_announce_fuzz_test.cc b/toxcore/group_announce_fuzz_test.cc
index 6728e712840..89c6cd9a9bc 100644
--- a/toxcore/group_announce_fuzz_test.cc
+++ b/toxcore/group_announce_fuzz_test.cc
@@ -6,6 +6,8 @@
 #include <vector>
 
 #include "../testing/fuzzing/fuzz_support.h"
+#include "os_memory.h"
+#include "tox_time_impl.h"
 
 namespace {
 
@@ -45,15 +47,17 @@ void TestUnpackPublicAnnounce(Fuzz_Data &input)
 
 void TestDoGca(Fuzz_Data &input)
 {
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     std::unique_ptr<Logger, void (*)(Logger *)> logger(logger_new(), logger_kill);
+    constexpr Tox_Time_Funcs mock_time_funcs = {
+        [](void *user_data) { return *static_cast<uint64_t *>(user_data); },
+    };
+    uint64_t clock = 1;
+    std::unique_ptr<Tox_Time, void (*)(Tox_Time *)> tm(
+        tox_time_new(&mock_time_funcs, &clock, mem), tox_time_free);
     std::unique_ptr<Mono_Time, std::function<void(Mono_Time *)>> mono_time(
-        mono_time_new(mem, nullptr, nullptr), [mem](Mono_Time *ptr) { mono_time_free(mem, ptr); });
+        mono_time_new(mem, tm.get()), [mem](Mono_Time *ptr) { mono_time_free(mem, ptr); });
     assert(mono_time != nullptr);
-    uint64_t clock = 1;
-    mono_time_set_current_time_callback(
-        mono_time.get(), [](void *user_data) { return *static_cast<uint64_t *>(user_data); },
-        &clock);
     std::unique_ptr<GC_Announces_List, void (*)(GC_Announces_List *)> gca(new_gca_list(), kill_gca);
     assert(gca != nullptr);
 
diff --git a/toxcore/group_announce_test.cc b/toxcore/group_announce_test.cc
index d3d5d715817..736bb8375f4 100644
--- a/toxcore/group_announce_test.cc
+++ b/toxcore/group_announce_test.cc
@@ -3,12 +3,18 @@
 #include <gtest/gtest.h>
 
 #include "mono_time.h"
+#include "os_memory.h"
+#include "tox_time_impl.h"
 
 namespace {
 
 struct Announces : ::testing::Test {
 protected:
-    const Memory *mem_ = system_memory();
+    const Memory *mem_ = os_memory();
+    static constexpr Tox_Time_Funcs mock_time_funcs = {
+        [](void *user_data) { return *static_cast<uint64_t *>(user_data); },
+    };
+    Tox_Time *tm_ = tox_time_new(&mock_time_funcs, &this->clock_, mem_);
     uint64_t clock_ = 0;
     Mono_Time *mono_time_ = nullptr;
     GC_Announces_List *gca_ = nullptr;
@@ -17,11 +23,8 @@ struct Announces : ::testing::Test {
 
     void SetUp() override
     {
-        mono_time_ = mono_time_new(mem_, nullptr, nullptr);
+        mono_time_ = mono_time_new(mem_, tm_);
         ASSERT_NE(mono_time_, nullptr);
-        mono_time_set_current_time_callback(
-            mono_time_, [](void *user_data) { return *static_cast<uint64_t *>(user_data); },
-            &clock_);
         gca_ = new_gca_list();
         ASSERT_NE(gca_, nullptr);
     }
@@ -30,6 +33,7 @@ struct Announces : ::testing::Test {
     {
         kill_gca(gca_);
         mono_time_free(mem_, mono_time_);
+        tox_time_free(tm_);
     }
 
     void advance_clock(uint64_t increment)
diff --git a/toxcore/group_chats.c b/toxcore/group_chats.c
index a18ba1494c9..e0d581ccb4b 100644
--- a/toxcore/group_chats.c
+++ b/toxcore/group_chats.c
@@ -153,7 +153,7 @@ non_null() static bool group_exists(const GC_Session *c, const uint8_t *chat_id)
 non_null() static void add_tcp_relays_to_chat(const GC_Session *c, GC_Chat *chat);
 non_null(1, 2) nullable(4)
 static bool peer_delete(const GC_Session *c, GC_Chat *chat, uint32_t peer_number, void *userdata);
-non_null() static void create_gc_session_keypair(const Logger *log, const Random *rng, uint8_t *public_key,
+non_null() static void create_gc_session_keypair(const Logger *log, const Tox_Random *rng, uint8_t *public_key,
         uint8_t *secret_key);
 non_null() static size_t load_gc_peers(GC_Chat *chat, const GC_SavedPeerInfo *addrs, uint16_t num_addrs);
 non_null() static bool saved_peer_is_valid(const GC_SavedPeerInfo *saved_peer);
@@ -744,7 +744,7 @@ static bool expand_chat_id(uint8_t *dest, const uint8_t *chat_id)
 
 /** Copies peer connect info from `gconn` to `addr`. */
 non_null()
-static void copy_gc_saved_peer(const Random *rng, const GC_Connection *gconn, GC_SavedPeerInfo *addr)
+static void copy_gc_saved_peer(const Tox_Random *rng, const GC_Connection *gconn, GC_SavedPeerInfo *addr)
 {
     if (!gcc_copy_tcp_relay(rng, &addr->tcp_relay, gconn)) {
         addr->tcp_relay = (Node_format) {
@@ -1469,7 +1469,7 @@ static int group_packet_unwrap(const Logger *log, const GC_Connection *gconn, ui
 }
 
 int group_packet_wrap(
-    const Logger *log, const Random *rng, const uint8_t *self_pk, const uint8_t *shared_key, uint8_t *packet,
+    const Logger *log, const Tox_Random *rng, const uint8_t *self_pk, const uint8_t *shared_key, uint8_t *packet,
     uint16_t packet_size, const uint8_t *data, uint16_t length, uint64_t message_id,
     uint8_t gp_packet_type, uint8_t net_packet_type)
 {
@@ -5401,7 +5401,7 @@ static int unwrap_group_handshake_packet(const Logger *log, const uint8_t *self_
  */
 non_null()
 static int wrap_group_handshake_packet(
-    const Logger *log, const Random *rng, const uint8_t *self_pk, const uint8_t *self_sk,
+    const Logger *log, const Tox_Random *rng, const uint8_t *self_pk, const uint8_t *self_sk,
     const uint8_t *target_pk, uint8_t *packet, uint32_t packet_size,
     const uint8_t *data, uint16_t length)
 {
@@ -7483,6 +7483,10 @@ int gc_group_load(GC_Session *c, Bin_Unpack *bu)
     chat->last_ping_interval = tm;
     chat->friend_connection_id = -1;
 
+    // Initialise these first, because we may need to log/dealloc things on cleanup.
+    chat->moderation.log = m->log;
+    chat->moderation.mem = m->mem;
+
     if (!gc_load_unpack_group(chat, bu)) {
         LOGGER_ERROR(chat->log, "Failed to unpack group");
         return -1;
@@ -8266,7 +8270,7 @@ static bool group_exists(const GC_Session *c, const uint8_t *chat_id)
 }
 
 /** Creates a new 32-byte session encryption keypair and puts the results in `public_key` and `secret_key`. */
-static void create_gc_session_keypair(const Logger *log, const Random *rng, uint8_t *public_key, uint8_t *secret_key)
+static void create_gc_session_keypair(const Logger *log, const Tox_Random *rng, uint8_t *public_key, uint8_t *secret_key)
 {
     if (crypto_new_keypair(rng, public_key, secret_key) != 0) {
         LOGGER_FATAL(log, "Failed to create group session keypair");
diff --git a/toxcore/group_chats.h b/toxcore/group_chats.h
index 821e629a641..02963bce663 100644
--- a/toxcore/group_chats.h
+++ b/toxcore/group_chats.h
@@ -140,7 +140,7 @@ int get_peer_number_of_enc_pk(const GC_Chat *chat, const uint8_t *public_enc_key
  */
 non_null(1, 2, 3, 4, 5) nullable(7)
 int group_packet_wrap(
-    const Logger *log, const Random *rng, const uint8_t *self_pk, const uint8_t *shared_key, uint8_t *packet,
+    const Logger *log, const Tox_Random *rng, const uint8_t *self_pk, const uint8_t *shared_key, uint8_t *packet,
     uint16_t packet_size, const uint8_t *data, uint16_t length, uint64_t message_id,
     uint8_t gp_packet_type, uint8_t net_packet_type);
 
diff --git a/toxcore/group_common.h b/toxcore/group_common.h
index 34d67dc8d62..65600d5f40a 100644
--- a/toxcore/group_common.h
+++ b/toxcore/group_common.h
@@ -248,7 +248,7 @@ typedef struct GC_Chat {
     Mono_Time       *mono_time;
     const Logger    *log;
     const Memory    *mem;
-    const Random    *rng;
+    const Tox_Random    *rng;
 
     uint32_t        connected_tcp_relays;
     Self_UDP_Status self_udp_status;
diff --git a/toxcore/group_connection.c b/toxcore/group_connection.c
index 86c353c00c0..b2e2cbe1ccc 100644
--- a/toxcore/group_connection.c
+++ b/toxcore/group_connection.c
@@ -268,7 +268,7 @@ void gcc_set_ip_port(GC_Connection *gconn, const IP_Port *ipp)
     }
 }
 
-bool gcc_copy_tcp_relay(const Random *rng, Node_format *tcp_node, const GC_Connection *gconn)
+bool gcc_copy_tcp_relay(const Tox_Random *rng, Node_format *tcp_node, const GC_Connection *gconn)
 {
     if (gconn == nullptr || tcp_node == nullptr) {
         return false;
@@ -289,7 +289,7 @@ bool gcc_copy_tcp_relay(const Random *rng, Node_format *tcp_node, const GC_Conne
     return true;
 }
 
-int gcc_save_tcp_relay(const Random *rng, GC_Connection *gconn, const Node_format *tcp_node)
+int gcc_save_tcp_relay(const Tox_Random *rng, GC_Connection *gconn, const Node_format *tcp_node)
 {
     if (gconn == nullptr || tcp_node == nullptr) {
         return -1;
diff --git a/toxcore/group_connection.h b/toxcore/group_connection.h
index 2202c7ab36e..3756baf8633 100644
--- a/toxcore/group_connection.h
+++ b/toxcore/group_connection.h
@@ -88,7 +88,7 @@ void gcc_set_ip_port(GC_Connection *gconn, const IP_Port *ipp);
  * Return true on success.
  */
 non_null()
-bool gcc_copy_tcp_relay(const Random *rng, Node_format *tcp_node, const GC_Connection *gconn);
+bool gcc_copy_tcp_relay(const Tox_Random *rng, Node_format *tcp_node, const GC_Connection *gconn);
 
 /** @brief Saves tcp_node to gconn's list of connected tcp relays.
  *
@@ -99,7 +99,7 @@ bool gcc_copy_tcp_relay(const Random *rng, Node_format *tcp_node, const GC_Conne
  * Return -2 if node is already in list.
  */
 non_null()
-int gcc_save_tcp_relay(const Random *rng, GC_Connection *gconn, const Node_format *tcp_node);
+int gcc_save_tcp_relay(const Tox_Random *rng, GC_Connection *gconn, const Node_format *tcp_node);
 
 /** @brief Checks for and handles messages that are in proper sequence in gconn's recv_array.
  * This should always be called after a new packet is successfully handled.
diff --git a/toxcore/group_moderation_fuzz_test.cc b/toxcore/group_moderation_fuzz_test.cc
index c5f46f3417c..dc4fbed76a1 100644
--- a/toxcore/group_moderation_fuzz_test.cc
+++ b/toxcore/group_moderation_fuzz_test.cc
@@ -1,13 +1,14 @@
 #include "group_moderation.h"
 
 #include "../testing/fuzzing/fuzz_support.h"
+#include "os_memory.h"
 
 namespace {
 
 void TestModListUnpack(Fuzz_Data &input)
 {
     CONSUME1_OR_RETURN(const uint16_t num_mods, input);
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     mod_list_unpack(&mods, input.data, input.size, num_mods);
     mod_list_cleanup(&mods);
 }
diff --git a/toxcore/group_moderation_test.cc b/toxcore/group_moderation_test.cc
index e55122896ad..07bec7c8141 100644
--- a/toxcore/group_moderation_test.cc
+++ b/toxcore/group_moderation_test.cc
@@ -8,6 +8,8 @@
 
 #include "crypto_core.h"
 #include "logger.h"
+#include "os_memory.h"
+#include "os_random.h"
 #include "util.h"
 
 namespace {
@@ -18,7 +20,7 @@ using ModerationHash = std::array<uint8_t, MOD_MODERATION_HASH_SIZE>;
 
 TEST(ModList, PackedSizeOfEmptyModListIsZero)
 {
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     EXPECT_EQ(mod_list_packed_size(&mods), 0);
 
     uint8_t byte = 1;
@@ -28,14 +30,14 @@ TEST(ModList, PackedSizeOfEmptyModListIsZero)
 
 TEST(ModList, UnpackingZeroSizeArrayIsNoop)
 {
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     const uint8_t byte = 1;
     EXPECT_EQ(mod_list_unpack(&mods, &byte, 0, 0), 0);
 }
 
 TEST(ModList, AddRemoveMultipleMods)
 {
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     uint8_t sig_pk1[32] = {1};
     uint8_t sig_pk2[32] = {2};
     EXPECT_TRUE(mod_list_add_entry(&mods, sig_pk1));
@@ -47,7 +49,7 @@ TEST(ModList, AddRemoveMultipleMods)
 TEST(ModList, PackingAndUnpackingList)
 {
     using ModListEntry = std::array<uint8_t, MOD_LIST_ENTRY_SIZE>;
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     EXPECT_TRUE(mod_list_add_entry(&mods, ModListEntry{}.data()));
 
     std::vector<uint8_t> packed(mod_list_packed_size(&mods));
@@ -55,7 +57,7 @@ TEST(ModList, PackingAndUnpackingList)
 
     EXPECT_TRUE(mod_list_remove_entry(&mods, ModListEntry{}.data()));
 
-    Moderation mods2{system_memory()};
+    Moderation mods2{os_memory()};
     EXPECT_EQ(mod_list_unpack(&mods2, packed.data(), packed.size(), 1), packed.size());
     EXPECT_TRUE(mod_list_remove_entry(&mods2, ModListEntry{}.data()));
 }
@@ -63,13 +65,13 @@ TEST(ModList, PackingAndUnpackingList)
 TEST(ModList, UnpackingTooManyModsFails)
 {
     using ModListEntry = std::array<uint8_t, MOD_LIST_ENTRY_SIZE>;
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     EXPECT_TRUE(mod_list_add_entry(&mods, ModListEntry{}.data()));
 
     std::vector<uint8_t> packed(mod_list_packed_size(&mods));
     mod_list_pack(&mods, packed.data());
 
-    Moderation mods2{system_memory()};
+    Moderation mods2{os_memory()};
     EXPECT_EQ(mod_list_unpack(&mods2, packed.data(), packed.size(), 2), -1);
     EXPECT_TRUE(mod_list_remove_entry(&mods, ModListEntry{}.data()));
 }
@@ -78,16 +80,16 @@ TEST(ModList, UnpackingFromEmptyBufferFails)
 {
     std::vector<uint8_t> packed(1);
 
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     EXPECT_EQ(mod_list_unpack(&mods, packed.end().base(), 0, 1), -1);
 }
 
 TEST(ModList, HashOfEmptyModListZeroesOutBuffer)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
 
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
 
     // Fill with random data, check that it's zeroed.
     ModerationHash hash;
@@ -98,21 +100,21 @@ TEST(ModList, HashOfEmptyModListZeroesOutBuffer)
 
 TEST(ModList, RemoveIndexFromEmptyModListFails)
 {
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     EXPECT_FALSE(mod_list_remove_index(&mods, 0));
     EXPECT_FALSE(mod_list_remove_index(&mods, UINT16_MAX));
 }
 
 TEST(ModList, RemoveEntryFromEmptyModListFails)
 {
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     uint8_t sig_pk[32] = {0};
     EXPECT_FALSE(mod_list_remove_entry(&mods, sig_pk));
 }
 
 TEST(ModList, ModListRemoveIndex)
 {
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     uint8_t sig_pk[32] = {1};
     EXPECT_TRUE(mod_list_add_entry(&mods, sig_pk));
     EXPECT_TRUE(mod_list_remove_index(&mods, 0));
@@ -120,20 +122,20 @@ TEST(ModList, ModListRemoveIndex)
 
 TEST(ModList, CleanupOnEmptyModsIsNoop)
 {
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     mod_list_cleanup(&mods);
 }
 
 TEST(ModList, EmptyModListCannotVerifyAnySigPk)
 {
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     uint8_t sig_pk[32] = {1};
     EXPECT_FALSE(mod_list_verify_sig_pk(&mods, sig_pk));
 }
 
 TEST(ModList, ModListAddVerifyRemoveSigPK)
 {
-    Moderation mods{system_memory()};
+    Moderation mods{os_memory()};
     uint8_t sig_pk[32] = {1};
     EXPECT_TRUE(mod_list_add_entry(&mods, sig_pk));
     EXPECT_TRUE(mod_list_verify_sig_pk(&mods, sig_pk));
@@ -143,7 +145,7 @@ TEST(ModList, ModListAddVerifyRemoveSigPK)
 
 TEST(ModList, ModListHashCheck)
 {
-    Moderation mods1{system_memory()};
+    Moderation mods1{os_memory()};
     uint8_t sig_pk1[32] = {1};
     std::array<uint8_t, MOD_MODERATION_HASH_SIZE> hash1;
 
@@ -165,7 +167,7 @@ TEST(SanctionsList, PackingIntoUndersizedBufferFails)
 
 TEST(SanctionsList, PackUnpackSanctionsCreds)
 {
-    Moderation mod{system_memory()};
+    Moderation mod{os_memory()};
     std::array<uint8_t, MOD_SANCTIONS_CREDS_SIZE> packed;
     EXPECT_EQ(sanctions_creds_pack(&mod.sanctions_creds, packed.data()), MOD_SANCTIONS_CREDS_SIZE);
     EXPECT_EQ(
@@ -177,7 +179,7 @@ struct SanctionsListMod : ::testing::Test {
     ExtPublicKey pk;
     ExtSecretKey sk;
     Logger *log = logger_new();
-    Moderation mod{system_memory()};
+    Moderation mod{os_memory()};
 
     Mod_Sanction sanctions[2] = {};
     const uint8_t sanctioned_pk1[32] = {1};
diff --git a/toxcore/group_onion_announce.c b/toxcore/group_onion_announce.c
index b797770e520..6e29d36ebe0 100644
--- a/toxcore/group_onion_announce.c
+++ b/toxcore/group_onion_announce.c
@@ -69,7 +69,7 @@ void gca_onion_init(GC_Announces_List *group_announce, Onion_Announce *onion_a)
 #ifndef VANILLA_NACL
 
 int create_gca_announce_request(
-    const Random *rng, uint8_t *packet, uint16_t max_packet_length, const uint8_t *dest_client_id,
+    const Tox_Random *rng, uint8_t *packet, uint16_t max_packet_length, const uint8_t *dest_client_id,
     const uint8_t *public_key, const uint8_t *secret_key, const uint8_t *ping_id,
     const uint8_t *client_id, const uint8_t *data_public_key, uint64_t sendback_data,
     const uint8_t *gc_data, uint16_t gc_data_length)
diff --git a/toxcore/group_onion_announce.h b/toxcore/group_onion_announce.h
index 5c6d64ec594..57f8cbd675e 100644
--- a/toxcore/group_onion_announce.h
+++ b/toxcore/group_onion_announce.h
@@ -14,7 +14,7 @@ void gca_onion_init(GC_Announces_List *group_announce, Onion_Announce *onion_a);
 
 non_null()
 int create_gca_announce_request(
-    const Random *rng, uint8_t *packet, uint16_t max_packet_length, const uint8_t *dest_client_id,
+    const Tox_Random *rng, uint8_t *packet, uint16_t max_packet_length, const uint8_t *dest_client_id,
     const uint8_t *public_key, const uint8_t *secret_key, const uint8_t *ping_id,
     const uint8_t *client_id, const uint8_t *data_public_key, uint64_t sendback_data,
     const uint8_t *gc_data, uint16_t gc_data_length);
diff --git a/toxcore/list.h b/toxcore/list.h
index a7c0e56c061..a05daf4f3cb 100644
--- a/toxcore/list.h
+++ b/toxcore/list.h
@@ -14,7 +14,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include "attributes.h"
+#include "tox_attributes.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/toxcore/logger.h b/toxcore/logger.h
index ee5838ae734..a879e11fb95 100644
--- a/toxcore/logger.h
+++ b/toxcore/logger.h
@@ -11,7 +11,7 @@
 
 #include <stdint.h>
 
-#include "attributes.h"
+#include "tox_attributes.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/toxcore/mem.c b/toxcore/mem.c
index a15b9728df6..424c86bfc0e 100644
--- a/toxcore/mem.c
+++ b/toxcore/mem.c
@@ -1,88 +1,35 @@
 /* SPDX-License-Identifier: GPL-3.0-or-later
- * Copyright © 2016-2018 The TokTok team.
+ * Copyright © 2016-2023 The TokTok team.
  * Copyright © 2013 Tox project.
  */
 
 #include "mem.h"
 
-#include <stdlib.h>
-
-#include "ccompat.h"
-
-nullable(1)
-static void *sys_malloc(void *obj, uint32_t size)
-{
-    return malloc(size);
-}
-
-nullable(1)
-static void *sys_calloc(void *obj, uint32_t nmemb, uint32_t size)
-{
-    return calloc(nmemb, size);
-}
-
-nullable(1, 2)
-static void *sys_realloc(void *obj, void *ptr, uint32_t size)
-{
-    return realloc(ptr, size);
-}
-
-nullable(1, 2)
-static void sys_free(void *obj, void *ptr)
-{
-    free(ptr);
-}
-
-static const Memory_Funcs system_memory_funcs = {
-    sys_malloc,
-    sys_calloc,
-    sys_realloc,
-    sys_free,
-};
-static const Memory system_memory_obj = {&system_memory_funcs};
-
-const Memory *system_memory(void)
-{
-    return &system_memory_obj;
-}
-
 void *mem_balloc(const Memory *mem, uint32_t size)
 {
-    void *const ptr = mem->funcs->malloc(mem->obj, size);
+    void *const ptr = tox_memory_malloc(mem, size);
     return ptr;
 }
 
 void *mem_alloc(const Memory *mem, uint32_t size)
 {
-    void *const ptr = mem->funcs->calloc(mem->obj, 1, size);
+    void *const ptr = tox_memory_calloc(mem, 1, size);
     return ptr;
 }
 
 void *mem_valloc(const Memory *mem, uint32_t nmemb, uint32_t size)
 {
-    const uint32_t bytes = nmemb * size;
-
-    if (size != 0 && bytes / size != nmemb) {
-        return nullptr;
-    }
-
-    void *const ptr = mem->funcs->calloc(mem->obj, nmemb, size);
+    void *const ptr = tox_memory_calloc(mem, nmemb, size);
     return ptr;
 }
 
 void *mem_vrealloc(const Memory *mem, void *ptr, uint32_t nmemb, uint32_t size)
 {
-    const uint32_t bytes = nmemb * size;
-
-    if (size != 0 && bytes / size != nmemb) {
-        return nullptr;
-    }
-
-    void *const new_ptr = mem->funcs->realloc(mem->obj, ptr, bytes);
+    void *const new_ptr = tox_memory_vrealloc(mem, ptr, nmemb, size);
     return new_ptr;
 }
 
 void mem_delete(const Memory *mem, void *ptr)
 {
-    mem->funcs->free(mem->obj, ptr);
+    tox_memory_dealloc(mem, ptr);
 }
diff --git a/toxcore/mem.h b/toxcore/mem.h
index a9d9e1d2c9a..a8c6899d60d 100644
--- a/toxcore/mem.h
+++ b/toxcore/mem.h
@@ -11,31 +11,14 @@
 
 #include <stdint.h>     // uint*_t
 
-#include "attributes.h"
+#include "tox_attributes.h"
+#include "tox_memory.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-typedef void *mem_malloc_cb(void *obj, uint32_t size);
-typedef void *mem_calloc_cb(void *obj, uint32_t nmemb, uint32_t size);
-typedef void *mem_realloc_cb(void *obj, void *ptr, uint32_t size);
-typedef void mem_free_cb(void *obj, void *ptr);
-
-/** @brief Functions wrapping standard C memory allocation functions. */
-typedef struct Memory_Funcs {
-    mem_malloc_cb *malloc;
-    mem_calloc_cb *calloc;
-    mem_realloc_cb *realloc;
-    mem_free_cb *free;
-} Memory_Funcs;
-
-typedef struct Memory {
-    const Memory_Funcs *funcs;
-    void *obj;
-} Memory;
-
-const Memory *system_memory(void);
+typedef Tox_Memory Memory;
 
 /**
  * @brief Allocate an array of a given size for built-in types.
diff --git a/toxcore/mem_test.cc b/toxcore/mem_test.cc
index f787036616c..bdd567cf07e 100644
--- a/toxcore/mem_test.cc
+++ b/toxcore/mem_test.cc
@@ -2,6 +2,8 @@
 
 #include <gtest/gtest.h>
 
+#include "os_memory.h"
+
 namespace {
 
 TEST(Mem, AllocLarge)
@@ -9,7 +11,7 @@ TEST(Mem, AllocLarge)
     // Mebi prefix: https://en.wikipedia.org/wiki/Binary_prefix.
     constexpr uint32_t MI = 1024 * 1024;
 
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
 
     void *ptr = mem_valloc(mem, 4, MI);
     EXPECT_NE(ptr, nullptr);
@@ -22,18 +24,18 @@ TEST(Mem, AllocOverflow)
     // Gibi prefix.
     constexpr uint32_t GI = 1024 * 1024 * 1024;
 
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
 
     // 1 gibi-elements of 100 bytes each.
-    void *ptr = mem_valloc(mem, GI, 100);
+    void *ptr = mem_vrealloc(mem, nullptr, GI, 100);
     EXPECT_EQ(ptr, nullptr);
 
     // 100 elements of 1 gibibyte each.
-    ptr = mem_valloc(mem, 100, GI);
+    ptr = mem_vrealloc(mem, nullptr, 100, GI);
     EXPECT_EQ(ptr, nullptr);
 
     // 128 (a multiple of 2) elements of 1 gibibyte each.
-    ptr = mem_valloc(mem, 128, GI);
+    ptr = mem_vrealloc(mem, nullptr, 128, GI);
     EXPECT_EQ(ptr, nullptr);
 }
 
diff --git a/toxcore/mono_time.c b/toxcore/mono_time.c
index e03046f799a..8683810fbef 100644
--- a/toxcore/mono_time.c
+++ b/toxcore/mono_time.c
@@ -32,6 +32,7 @@
 #include <time.h>
 
 #include "ccompat.h"
+#include "tox_time_impl.h"
 
 /** don't call into system billions of times for no reason */
 struct Mono_Time {
@@ -49,8 +50,8 @@ struct Mono_Time {
     pthread_rwlock_t *time_update_lock;
 #endif
 
-    mono_time_current_time_cb *current_time_callback;
-    void *user_data;
+    const Tox_Time *tm;
+    Tox_Time default_tm;
 };
 
 #ifdef OS_WIN32
@@ -121,8 +122,12 @@ static uint64_t current_time_monotonic_default(void *user_data)
 #endif // !__APPLE__
 #endif // !OS_WIN32
 
+static const Tox_Time_Funcs os_time_funcs = {
+    current_time_monotonic_default,
+};
+
 
-Mono_Time *mono_time_new(const Memory *mem, mono_time_current_time_cb *current_time_callback, void *user_data)
+Mono_Time *mono_time_new(const Memory *mem, const Tox_Time *tm)
 {
     Mono_Time *mono_time = (Mono_Time *)mem_alloc(mem, sizeof(Mono_Time));
 
@@ -145,7 +150,10 @@ Mono_Time *mono_time_new(const Memory *mem, mono_time_current_time_cb *current_t
     }
 #endif
 
-    mono_time_set_current_time_callback(mono_time, current_time_callback, user_data);
+    mono_time->default_tm.funcs = &os_time_funcs;
+    mono_time->default_tm.user_data = mono_time;
+
+    mono_time->tm = tm != nullptr ? tm : &mono_time->default_tm;
 
 #ifdef OS_WIN32
 
@@ -196,7 +204,7 @@ void mono_time_update(Mono_Time *mono_time)
     pthread_mutex_lock(&mono_time->last_clock_lock);
     mono_time->last_clock_update = true;
 #endif
-    cur_time = mono_time->current_time_callback(mono_time->user_data) / 1000ULL;
+    cur_time = tox_time_monotonic(mono_time->tm) / 1000ULL;
     cur_time += mono_time->base_time;
 #ifdef OS_WIN32
     pthread_mutex_unlock(&mono_time->last_clock_lock);
@@ -233,16 +241,9 @@ bool mono_time_is_timeout(const Mono_Time *mono_time, uint64_t timestamp, uint64
     return timestamp + timeout <= mono_time_get(mono_time);
 }
 
-void mono_time_set_current_time_callback(Mono_Time *mono_time,
-        mono_time_current_time_cb *current_time_callback, void *user_data)
+void mono_time_set_current_time_callback(Mono_Time *mono_time, const Tox_Time *tm)
 {
-    if (current_time_callback == nullptr) {
-        mono_time->current_time_callback = current_time_monotonic_default;
-        mono_time->user_data = mono_time;
-    } else {
-        mono_time->current_time_callback = current_time_callback;
-        mono_time->user_data = user_data;
-    }
+    mono_time->tm = tm != nullptr ? tm : &mono_time->default_tm;
 }
 
 /**
@@ -257,7 +258,7 @@ uint64_t current_time_monotonic(Mono_Time *mono_time)
      * but must protect against other threads */
     pthread_mutex_lock(&mono_time->last_clock_lock);
 #endif
-    const uint64_t cur_time = mono_time->current_time_callback(mono_time->user_data);
+    const uint64_t cur_time = tox_time_monotonic(mono_time->tm);
 #ifdef OS_WIN32
     pthread_mutex_unlock(&mono_time->last_clock_lock);
 #endif
diff --git a/toxcore/mono_time.h b/toxcore/mono_time.h
index fa1df840e0c..b98bcf971ae 100644
--- a/toxcore/mono_time.h
+++ b/toxcore/mono_time.h
@@ -8,8 +8,9 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include "attributes.h"
 #include "mem.h"
+#include "tox_attributes.h"
+#include "tox_time.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -46,10 +47,8 @@ extern "C" {
  */
 typedef struct Mono_Time Mono_Time;
 
-typedef uint64_t mono_time_current_time_cb(void *user_data);
-
-non_null(1) nullable(2, 3)
-Mono_Time *mono_time_new(const Memory *mem, mono_time_current_time_cb *current_time_callback, void *user_data);
+non_null(1) nullable(2)
+Mono_Time *mono_time_new(const Memory *mem, const Tox_Time *tm);
 
 non_null(1) nullable(2)
 void mono_time_free(const Memory *mem, Mono_Time *mono_time);
@@ -86,9 +85,8 @@ uint64_t current_time_monotonic(Mono_Time *mono_time);
  * The caller is obligated to ensure that `current_time_monotonic()` continues
  * to increase monotonically.
  */
-non_null(1) nullable(2, 3)
-void mono_time_set_current_time_callback(Mono_Time *mono_time,
-        mono_time_current_time_cb *current_time_callback, void *user_data);
+non_null(1) nullable(2)
+void mono_time_set_current_time_callback(Mono_Time *mono_time, const Tox_Time *tm);
 
 #ifdef __cplusplus
 }
diff --git a/toxcore/mono_time_test.cc b/toxcore/mono_time_test.cc
index 379b606c8e5..ffc6d42d553 100644
--- a/toxcore/mono_time_test.cc
+++ b/toxcore/mono_time_test.cc
@@ -2,12 +2,15 @@
 
 #include <gtest/gtest.h>
 
+#include "os_memory.h"
+#include "tox_time_impl.h"
+
 namespace {
 
 TEST(MonoTime, UnixTimeIncreasesOverTime)
 {
-    const Memory *mem = system_memory();
-    Mono_Time *mono_time = mono_time_new(mem, nullptr, nullptr);
+    const Memory *mem = os_memory();
+    Mono_Time *mono_time = mono_time_new(mem, nullptr);
     ASSERT_NE(mono_time, nullptr);
 
     mono_time_update(mono_time);
@@ -25,8 +28,8 @@ TEST(MonoTime, UnixTimeIncreasesOverTime)
 
 TEST(MonoTime, IsTimeout)
 {
-    const Memory *mem = system_memory();
-    Mono_Time *mono_time = mono_time_new(mem, nullptr, nullptr);
+    const Memory *mem = os_memory();
+    Mono_Time *mono_time = mono_time_new(mem, nullptr);
     ASSERT_NE(mono_time, nullptr);
 
     uint64_t const start = mono_time_get(mono_time);
@@ -43,14 +46,17 @@ TEST(MonoTime, IsTimeout)
 
 TEST(MonoTime, CustomTime)
 {
-    const Memory *mem = system_memory();
-    Mono_Time *mono_time = mono_time_new(mem, nullptr, nullptr);
+    const Memory *mem = os_memory();
+    Mono_Time *mono_time = mono_time_new(mem, nullptr);
     ASSERT_NE(mono_time, nullptr);
 
     uint64_t test_time = current_time_monotonic(mono_time) + 42137;
 
-    mono_time_set_current_time_callback(
-        mono_time, [](void *user_data) { return *static_cast<uint64_t *>(user_data); }, &test_time);
+    constexpr Tox_Time_Funcs mock_time_funcs = {
+        [](void *user_data) { return *static_cast<uint64_t *>(user_data); },
+    };
+    Tox_Time *tm = tox_time_new(&mock_time_funcs, &test_time, mem);
+    mono_time_set_current_time_callback(mono_time, tm);
     mono_time_update(mono_time);
 
     EXPECT_EQ(current_time_monotonic(mono_time), test_time);
@@ -65,6 +71,7 @@ TEST(MonoTime, CustomTime)
     EXPECT_EQ(current_time_monotonic(mono_time), test_time);
 
     mono_time_free(mem, mono_time);
+    tox_time_free(tm);
 }
 
 }  // namespace
diff --git a/toxcore/net_crypto.c b/toxcore/net_crypto.c
index 7fb4b3a8139..20759b09152 100644
--- a/toxcore/net_crypto.c
+++ b/toxcore/net_crypto.c
@@ -128,7 +128,7 @@ static const Crypto_Connection empty_crypto_connection = {{0}};
 struct Net_Crypto {
     const Logger *log;
     const Memory *mem;
-    const Random *rng;
+    const Tox_Random *rng;
     Mono_Time *mono_time;
     const Network *ns;
 
@@ -247,7 +247,7 @@ static int create_cookie_request(const Net_Crypto *c, uint8_t *packet, const uin
  * @retval 0 on success.
  */
 non_null()
-static int create_cookie(const Random *rng, const Mono_Time *mono_time, uint8_t *cookie, const uint8_t *bytes,
+static int create_cookie(const Tox_Random *rng, const Mono_Time *mono_time, uint8_t *cookie, const uint8_t *bytes,
                          const uint8_t *encryption_key)
 {
     uint8_t contents[COOKIE_CONTENTS_LENGTH];
@@ -3108,7 +3108,7 @@ void load_secret_key(Net_Crypto *c, const uint8_t *sk)
 /** @brief Create new instance of Net_Crypto.
  * Sets all the global connection variables to their default values.
  */
-Net_Crypto *new_net_crypto(const Logger *log, const Memory *mem, const Random *rng, const Network *ns,
+Net_Crypto *new_net_crypto(const Logger *log, const Memory *mem, const Tox_Random *rng, const Network *ns,
                            Mono_Time *mono_time, DHT *dht, const TCP_Proxy_Info *proxy_info)
 {
     if (dht == nullptr) {
diff --git a/toxcore/net_crypto.h b/toxcore/net_crypto.h
index ac6a0b59cbd..38b58ffe61b 100644
--- a/toxcore/net_crypto.h
+++ b/toxcore/net_crypto.h
@@ -398,7 +398,7 @@ void load_secret_key(Net_Crypto *c, const uint8_t *sk);
  * Sets all the global connection variables to their default values.
  */
 non_null()
-Net_Crypto *new_net_crypto(const Logger *log, const Memory *mem, const Random *rng, const Network *ns,
+Net_Crypto *new_net_crypto(const Logger *log, const Memory *mem, const Tox_Random *rng, const Network *ns,
                            Mono_Time *mono_time, DHT *dht, const TCP_Proxy_Info *proxy_info);
 
 /** return the optimal interval in ms for running do_net_crypto. */
diff --git a/toxcore/network.c b/toxcore/network.c
index 5ccf068f53c..9b2d2146fde 100644
--- a/toxcore/network.c
+++ b/toxcore/network.c
@@ -37,12 +37,6 @@
 
 #include "network.h"
 
-#ifdef PLAN9
-#include <u.h> // Plan 9 requires this is imported first
-// Comment line here to avoid reordering by source code formatters.
-#include <libc.h>
-#endif
-
 #ifdef OS_WIN32 // Put win32 includes here
 // The mingw32/64 Windows library warns about including winsock2.h after
 // windows.h even though with the above it's a valid thing to do. So, to make
@@ -53,11 +47,6 @@
 #include <ws2tcpip.h>
 #endif
 
-#ifdef __APPLE__
-#include <mach/clock.h>
-#include <mach/mach.h>
-#endif
-
 #if !defined(OS_WIN32)
 #include <arpa/inet.h>
 #include <errno.h>
@@ -87,21 +76,12 @@
 #include <stdlib.h>
 #include <string.h>
 
-#ifndef VANILLA_NACL
-// Used for sodium_init()
-#include <sodium.h>
-#endif
-
 #include "ccompat.h"
 #include "logger.h"
 #include "mono_time.h"
+#include "os_network_impl.h"
 #include "util.h"
 
-// Disable MSG_NOSIGNAL on systems not supporting it, e.g. Windows, FreeBSD
-#if !defined(MSG_NOSIGNAL)
-#define MSG_NOSIGNAL 0
-#endif
-
 #ifndef IPV6_ADD_MEMBERSHIP
 #ifdef IPV6_JOIN_GROUP
 #define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
@@ -377,47 +357,47 @@ IP6 get_ip6_loopback(void)
 
 const Socket net_invalid_socket = { (int)INVALID_SOCKET };
 
-Family net_family_unspec()
+Family net_family_unspec(void)
 {
     return family_unspec;
 }
 
-Family net_family_ipv4()
+Family net_family_ipv4(void)
 {
     return family_ipv4;
 }
 
-Family net_family_ipv6()
+Family net_family_ipv6(void)
 {
     return family_ipv6;
 }
 
-Family net_family_tcp_server()
+Family net_family_tcp_server(void)
 {
     return family_tcp_server;
 }
 
-Family net_family_tcp_client()
+Family net_family_tcp_client(void)
 {
     return family_tcp_client;
 }
 
-Family net_family_tcp_ipv4()
+Family net_family_tcp_ipv4(void)
 {
     return family_tcp_ipv4;
 }
 
-Family net_family_tcp_ipv6()
+Family net_family_tcp_ipv6(void)
 {
     return family_tcp_ipv6;
 }
 
-Family net_family_tox_tcp_ipv4()
+Family net_family_tox_tcp_ipv4(void)
 {
     return family_tox_tcp_ipv4;
 }
 
-Family net_family_tox_tcp_ipv6()
+Family net_family_tox_tcp_ipv6(void)
 {
     return family_tox_tcp_ipv6;
 }
@@ -472,147 +452,9 @@ bool sock_valid(Socket sock)
     return sock.sock != net_invalid_socket.sock;
 }
 
-struct Network_Addr {
-    struct sockaddr_storage addr;
-    size_t size;
-};
-
-non_null()
-static int sys_close(void *obj, int sock)
-{
-#if defined(OS_WIN32)
-    return closesocket(sock);
-#else  // !OS_WIN32
-    return close(sock);
-#endif
-}
-
-non_null()
-static int sys_accept(void *obj, int sock)
-{
-    return accept(sock, nullptr, nullptr);
-}
-
-non_null()
-static int sys_bind(void *obj, int sock, const Network_Addr *addr)
-{
-    return bind(sock, (const struct sockaddr *)&addr->addr, addr->size);
-}
-
-non_null()
-static int sys_listen(void *obj, int sock, int backlog)
-{
-    return listen(sock, backlog);
-}
-
-non_null()
-static int sys_recvbuf(void *obj, int sock)
-{
-#ifdef OS_WIN32
-    u_long count = 0;
-    ioctlsocket(sock, FIONREAD, &count);
-#else
-    int count = 0;
-    ioctl(sock, FIONREAD, &count);
-#endif
-
-    return count;
-}
-
-non_null()
-static int sys_recv(void *obj, int sock, uint8_t *buf, size_t len)
-{
-    return recv(sock, (char *)buf, len, MSG_NOSIGNAL);
-}
-
-non_null()
-static int sys_send(void *obj, int sock, const uint8_t *buf, size_t len)
-{
-    return send(sock, (const char *)buf, len, MSG_NOSIGNAL);
-}
-
-non_null()
-static int sys_sendto(void *obj, int sock, const uint8_t *buf, size_t len, const Network_Addr *addr) {
-    return sendto(sock, (const char *)buf, len, 0, (const struct sockaddr *)&addr->addr, addr->size);
-}
-
-non_null()
-static int sys_recvfrom(void *obj, int sock, uint8_t *buf, size_t len, Network_Addr *addr) {
-    socklen_t size = addr->size;
-    const int ret = recvfrom(sock, (char *)buf, len, 0, (struct sockaddr *)&addr->addr, &size);
-    addr->size = size;
-    return ret;
-}
-
-non_null()
-static int sys_socket(void *obj, int domain, int type, int proto)
-{
-    return (int)socket(domain, type, proto);
-}
-
-non_null()
-static int sys_socket_nonblock(void *obj, int sock, bool nonblock)
-{
-#ifdef OS_WIN32
-    u_long mode = nonblock ? 1 : 0;
-    return ioctlsocket(sock, FIONBIO, &mode);
-#else
-    return fcntl(sock, F_SETFL, O_NONBLOCK, nonblock ? 1 : 0);
-#endif /* OS_WIN32 */
-}
-
-non_null()
-static int sys_getsockopt(void *obj, int sock, int level, int optname, void *optval, size_t *optlen)
-{
-    socklen_t len = *optlen;
-    const int ret = getsockopt(sock, level, optname, optval, &len);
-    *optlen = len;
-    return ret;
-}
-
-non_null()
-static int sys_setsockopt(void *obj, int sock, int level, int optname, const void *optval, size_t optlen)
-{
-    return setsockopt(sock, level, optname, optval, optlen);
-}
-
-static const Network_Funcs system_network_funcs = {
-    sys_close,
-    sys_accept,
-    sys_bind,
-    sys_listen,
-    sys_recvbuf,
-    sys_recv,
-    sys_recvfrom,
-    sys_send,
-    sys_sendto,
-    sys_socket,
-    sys_socket_nonblock,
-    sys_getsockopt,
-    sys_setsockopt,
-};
-static const Network system_network_obj = {&system_network_funcs};
-
-const Network *system_network(void)
-{
-#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
-    if ((true)) {
-        return nullptr;
-    }
-#endif
-#ifdef OS_WIN32
-    WSADATA wsaData;
-
-    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != NO_ERROR) {
-        return nullptr;
-    }
-#endif
-    return &system_network_obj;
-}
-
 #if 0
-/* TODO(iphydf): Call this from functions that use `system_network()`. */
-void system_network_deinit(const Network *ns)
+/* TODO(iphydf): Call this from functions that use `os_network()`. */
+void os_network_deinit(const Network *ns)
 {
 #ifdef OS_WIN32
     WSACleanup();
@@ -623,13 +465,13 @@ void system_network_deinit(const Network *ns)
 non_null()
 static int net_setsockopt(const Network *ns, Socket sock, int level, int optname, const void *optval, size_t optlen)
 {
-    return ns->funcs->setsockopt(ns->obj, sock.sock, level, optname, optval, optlen);
+    return tox_network_setsockopt(ns, sock.sock, level, optname, optval, optlen);
 }
 
 non_null()
 static int net_getsockopt(const Network *ns, Socket sock, int level, int optname, void *optval, size_t *optlen)
 {
-    return ns->funcs->getsockopt(ns->obj, sock.sock, level, optname, optval, optlen);
+    return tox_network_getsockopt(ns, sock.sock, level, optname, optval, optlen);
 }
 
 non_null()
@@ -804,7 +646,7 @@ static void loglogdata(const Logger *log, const char *message, const uint8_t *bu
 int net_send(const Network *ns, const Logger *log,
              Socket sock, const uint8_t *buf, size_t len, const IP_Port *ip_port)
 {
-    const int res = ns->funcs->send(ns->obj, sock.sock, buf, len);
+    const int res = tox_network_send(ns, sock.sock, buf, len);
     loglogdata(log, "T=>", buf, len, ip_port, res);
     return res;
 }
@@ -814,13 +656,13 @@ static int net_sendto(
         const Network *ns,
         Socket sock, const uint8_t *buf, size_t len, const Network_Addr *addr, const IP_Port *ip_port)
 {
-    return ns->funcs->sendto(ns->obj, sock.sock, buf, len, addr);
+    return tox_network_sendto(ns, sock.sock, buf, len, addr);
 }
 
 int net_recv(const Network *ns, const Logger *log,
              Socket sock, uint8_t *buf, size_t len, const IP_Port *ip_port)
 {
-    const int res = ns->funcs->recv(ns->obj, sock.sock, buf, len);
+    const int res = tox_network_recv(ns, sock.sock, buf, len);
     loglogdata(log, "=>T", buf, len, ip_port, res);
     return res;
 }
@@ -829,35 +671,35 @@ non_null()
 static int net_recvfrom(const Network *ns,
                         Socket sock, uint8_t *buf, size_t len, Network_Addr *addr)
 {
-    return ns->funcs->recvfrom(ns->obj, sock.sock, buf, len, addr);
+    return tox_network_recvfrom(ns, sock.sock, buf, len, addr);
 }
 
 int net_listen(const Network *ns, Socket sock, int backlog)
 {
-    return ns->funcs->listen(ns->obj, sock.sock, backlog);
+    return tox_network_listen(ns, sock.sock, backlog);
 }
 
 non_null()
 static int net_bind(const Network *ns, Socket sock, const Network_Addr *addr)
 {
-    return ns->funcs->bind(ns->obj, sock.sock, addr);
+    return tox_network_bind(ns, sock.sock, addr);
 }
 
 Socket net_accept(const Network *ns, Socket sock)
 {
-    const Socket newsock = {ns->funcs->accept(ns->obj, sock.sock)};
+    const Socket newsock = {tox_network_accept(ns, sock.sock)};
     return newsock;
 }
 
 /** Close the socket. */
 void kill_sock(const Network *ns, Socket sock)
 {
-    ns->funcs->close(ns->obj, sock.sock);
+    tox_network_close(ns, sock.sock);
 }
 
 bool set_socket_nonblock(const Network *ns, Socket sock)
 {
-    return ns->funcs->socket_nonblock(ns->obj, sock.sock, true) == 0;
+    return tox_network_socket_nonblock(ns, sock.sock, true) == 0;
 }
 
 bool set_socket_nosigpipe(const Network *ns, Socket sock)
@@ -962,34 +804,41 @@ int send_packet(const Networking_Core *net, const IP_Port *ip_port, Packet packe
         ipp_copy.ip.ip.v6 = ip6;
     }
 
-    Network_Addr addr;
+    Network_Addr *addr;
 
     if (net_family_is_ipv4(ipp_copy.ip.family)) {
-        struct sockaddr_in *const addr4 = (struct sockaddr_in *)&addr.addr;
+        struct sockaddr_in addr4 = {0};
 
-        addr.size = sizeof(struct sockaddr_in);
-        addr4->sin_family = AF_INET;
-        addr4->sin_port = ipp_copy.port;
-        fill_addr4(&ipp_copy.ip.ip.v4, &addr4->sin_addr);
+        addr4.sin_family = AF_INET;
+        addr4.sin_port = ipp_copy.port;
+        fill_addr4(&ipp_copy.ip.ip.v4, &addr4.sin_addr);
+
+        addr = net_addr_new(&addr4, sizeof(addr4), net->mem);
     } else if (net_family_is_ipv6(ipp_copy.ip.family)) {
-        struct sockaddr_in6 *const addr6 = (struct sockaddr_in6 *)&addr.addr;
+        struct sockaddr_in6 addr6 = {0};
 
-        addr.size = sizeof(struct sockaddr_in6);
-        addr6->sin6_family = AF_INET6;
-        addr6->sin6_port = ipp_copy.port;
-        fill_addr6(&ipp_copy.ip.ip.v6, &addr6->sin6_addr);
+        addr6.sin6_family = AF_INET6;
+        addr6.sin6_port = ipp_copy.port;
+        fill_addr6(&ipp_copy.ip.ip.v6, &addr6.sin6_addr);
 
-        addr6->sin6_flowinfo = 0;
-        addr6->sin6_scope_id = 0;
+        addr6.sin6_flowinfo = 0;
+        addr6.sin6_scope_id = 0;
+
+        addr = net_addr_new(&addr6, sizeof(addr6), net->mem);
     } else {
         LOGGER_ERROR(net->log, "unknown address type: %d", ipp_copy.ip.family.value);
         return -1;
     }
 
-    const long res = net_sendto(net->ns, net->sock, packet.data, packet.length, &addr, &ipp_copy);
+    if (addr == nullptr) {
+        return -1;
+    }
+
+    const long res = net_sendto(net->ns, net->sock, packet.data, packet.length, addr, &ipp_copy);
     loglogdata(net->log, "O=>", packet.data, packet.length, ip_port, res);
 
     assert(res <= INT_MAX);
+    net_addr_free(addr, net->mem);
     return (int)res;
 }
 
@@ -1013,11 +862,14 @@ non_null()
 static int receivepacket(const Network *ns, const Memory *mem, const Logger *log, Socket sock, IP_Port *ip_port, uint8_t *data, uint32_t *length)
 {
     memset(ip_port, 0, sizeof(IP_Port));
-    Network_Addr addr = {{0}};
-    addr.size = sizeof(addr.addr);
+    Network_Addr *addr = net_addr_new(nullptr, 0, mem);
     *length = 0;
 
-    const int fail_or_len = net_recvfrom(ns, sock, data, MAX_UDP_PACKET_SIZE, &addr);
+    if (addr == nullptr) {
+        return -1;
+    }
+
+    const int fail_or_len = net_recvfrom(ns, sock, data, MAX_UDP_PACKET_SIZE, addr);
 
     if (fail_or_len < 0) {
         const int error = net_error();
@@ -1028,30 +880,33 @@ static int receivepacket(const Network *ns, const Memory *mem, const Logger *log
             net_kill_strerror(strerror);
         }
 
+        net_addr_free(addr, mem);
         return -1; /* Nothing received. */
     }
 
     *length = (uint32_t)fail_or_len;
 
-    if (addr.addr.ss_family == AF_INET) {
-        const struct sockaddr_in *addr_in = (const struct sockaddr_in *)&addr.addr;
+    if (net_addr_is_ipv4(addr)) {
+        const struct sockaddr_in *addr_in = (const struct sockaddr_in *)net_addr_get_addr(addr);
 
         const Family *const family = make_tox_family(addr_in->sin_family);
         assert(family != nullptr);
 
         if (family == nullptr) {
+            net_addr_free(addr, mem);
             return -1;
         }
 
         ip_port->ip.family = *family;
         get_ip4(&ip_port->ip.ip.v4, &addr_in->sin_addr);
         ip_port->port = addr_in->sin_port;
-    } else if (addr.addr.ss_family == AF_INET6) {
-        const struct sockaddr_in6 *addr_in6 = (const struct sockaddr_in6 *)&addr.addr;
+    } else if (net_addr_is_ipv6(addr)) {
+        const struct sockaddr_in6 *addr_in6 = (const struct sockaddr_in6 *)net_addr_get_addr(addr);
         const Family *const family = make_tox_family(addr_in6->sin6_family);
         assert(family != nullptr);
 
         if (family == nullptr) {
+            net_addr_free(addr, mem);
             return -1;
         }
 
@@ -1064,11 +919,13 @@ static int receivepacket(const Network *ns, const Memory *mem, const Logger *log
             ip_port->ip.ip.v4.uint32 = ip_port->ip.ip.v6.uint32[3];
         }
     } else {
+        net_addr_free(addr, mem);
         return -1;
     }
 
     loglogdata(log, "=>O", data, MAX_UDP_PACKET_SIZE, ip_port, *length);
 
+    net_addr_free(addr, mem);
     return 0;
 }
 
@@ -1222,23 +1079,31 @@ Networking_Core *new_networking_ex(
 
     /* Bind our socket to port PORT and the given IP address (usually 0.0.0.0 or ::) */
     uint16_t *portptr = nullptr;
-    Network_Addr addr;
+    Network_Addr *addr = net_addr_new(nullptr, 0, mem);
 
-    memset(&addr.addr, 0, sizeof(struct sockaddr_storage));
+    if (addr == nullptr) {
+        kill_networking(temp);
+
+        if (error != nullptr) {
+            *error = 2;
+        }
+
+        return nullptr;
+    }
 
     if (net_family_is_ipv4(temp->family)) {
-        struct sockaddr_in *addr4 = (struct sockaddr_in *)&addr.addr;
+        struct sockaddr_in *addr4 = (struct sockaddr_in *)net_addr_mut_addr(addr);
 
-        addr.size = sizeof(struct sockaddr_in);
+        net_addr_set_size(addr, sizeof(struct sockaddr_in));
         addr4->sin_family = AF_INET;
         addr4->sin_port = 0;
         fill_addr4(&ip->ip.v4, &addr4->sin_addr);
 
         portptr = &addr4->sin_port;
     } else if (net_family_is_ipv6(temp->family)) {
-        struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&addr.addr;
+        struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)net_addr_mut_addr(addr);
 
-        addr.size = sizeof(struct sockaddr_in6);
+        net_addr_set_size(addr, sizeof(struct sockaddr_in6));
         addr6->sin6_family = AF_INET6;
         addr6->sin6_port = 0;
         fill_addr6(&ip->ip.v6, &addr6->sin6_addr);
@@ -1249,6 +1114,7 @@ Networking_Core *new_networking_ex(
         portptr = &addr6->sin6_port;
     } else {
         mem_delete(mem, temp);
+        net_addr_free(addr, mem);
         return nullptr;
     }
 
@@ -1305,7 +1171,7 @@ Networking_Core *new_networking_ex(
     *portptr = net_htons(port_to_try);
 
     for (uint16_t tries = port_from; tries <= port_to; ++tries) {
-        const int res = net_bind(ns, temp->sock, &addr);
+        const int res = net_bind(ns, temp->sock, addr);
 
         if (res == 0) {
             temp->port = *portptr;
@@ -1325,6 +1191,7 @@ Networking_Core *new_networking_ex(
                 *error = 0;
             }
 
+            net_addr_free(addr, mem);
             return temp;
         }
 
@@ -1349,6 +1216,7 @@ Networking_Core *new_networking_ex(
         *error = 1;
     }
 
+    net_addr_free(addr, mem);
     return nullptr;
 }
 
@@ -1777,6 +1645,7 @@ int32_t net_getipport(const Memory *mem, const char *node, IP_Port **res, int to
         IP_Port *tmp = (IP_Port *)mem_alloc(mem, sizeof(IP_Port));
 
         if (tmp == nullptr) {
+            *res = nullptr;
             return -1;
         }
 
@@ -1788,7 +1657,11 @@ int32_t net_getipport(const Memory *mem, const char *node, IP_Port **res, int to
 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
     if ((true)) {
         *res = (IP_Port *)mem_alloc(mem, sizeof(IP_Port));
-        assert(*res != nullptr);
+
+        if (*res == nullptr) {
+            return -1;
+        }
+
         IP_Port *ip_port = *res;
         ip_port->ip.ip.v4.uint32 = net_htonl(0x7F000003); // 127.0.0.3
         ip_port->ip.family = *make_tox_family(AF_INET);
@@ -1877,27 +1750,31 @@ void net_freeipport(const Memory *mem, IP_Port *ip_ports)
     mem_delete(mem, ip_ports);
 }
 
-bool bind_to_port(const Network *ns, Socket sock, Family family, uint16_t port)
+bool bind_to_port(const Network *ns, const Memory *mem, Socket sock, Family family, uint16_t port)
 {
-    Network_Addr addr = {{0}};
+    Network_Addr *addr;
 
     if (net_family_is_ipv4(family)) {
-        struct sockaddr_in *addr4 = (struct sockaddr_in *)&addr.addr;
+        struct sockaddr_in addr4 = {0};
 
-        addr.size = sizeof(struct sockaddr_in);
-        addr4->sin_family = AF_INET;
-        addr4->sin_port = net_htons(port);
+        addr4.sin_family = AF_INET;
+        addr4.sin_port = net_htons(port);
+
+        addr = net_addr_new(&addr4, sizeof(addr4), mem);
     } else if (net_family_is_ipv6(family)) {
-        struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&addr.addr;
+        struct sockaddr_in6 addr6 = {0};
 
-        addr.size = sizeof(struct sockaddr_in6);
-        addr6->sin6_family = AF_INET6;
-        addr6->sin6_port = net_htons(port);
+        addr6.sin6_family = AF_INET6;
+        addr6.sin6_port = net_htons(port);
+
+        addr = net_addr_new(&addr6, sizeof(addr6), mem);
     } else {
         return false;
     }
 
-    return net_bind(ns, sock, &addr) == 0;
+    const bool ok = net_bind(ns, sock, addr) == 0;
+    net_addr_free(addr, mem);
+    return ok;
 }
 
 Socket net_socket(const Network *ns, Family domain, int type, int protocol)
@@ -1905,13 +1782,13 @@ Socket net_socket(const Network *ns, Family domain, int type, int protocol)
     const int platform_domain = make_family(domain);
     const int platform_type = make_socktype(type);
     const int platform_prot = make_proto(protocol);
-    const Socket sock = {ns->funcs->socket(ns->obj, platform_domain, platform_type, platform_prot)};
+    const Socket sock = {tox_network_socket(ns, platform_domain, platform_type, platform_prot)};
     return sock;
 }
 
 uint16_t net_socket_data_recv_buffer(const Network *ns, Socket sock)
 {
-    const int count = ns->funcs->recvbuf(ns->obj, sock.sock);
+    const int count = tox_network_recvbuf(ns, sock.sock);
     return (uint16_t)max_s32(0, min_s32(count, UINT16_MAX));
 }
 
diff --git a/toxcore/network.h b/toxcore/network.h
index 2f518c1d910..59b4a10a019 100644
--- a/toxcore/network.h
+++ b/toxcore/network.h
@@ -15,62 +15,12 @@
 
 #include "logger.h"
 #include "mem.h"
+#include "tox_network.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-/**
- * @brief Wrapper for sockaddr_storage and size.
- */
-typedef struct Network_Addr Network_Addr;
-
-typedef int net_close_cb(void *obj, int sock);
-typedef int net_accept_cb(void *obj, int sock);
-typedef int net_bind_cb(void *obj, int sock, const Network_Addr *addr);
-typedef int net_listen_cb(void *obj, int sock, int backlog);
-typedef int net_recvbuf_cb(void *obj, int sock);
-typedef int net_recv_cb(void *obj, int sock, uint8_t *buf, size_t len);
-typedef int net_recvfrom_cb(void *obj, int sock, uint8_t *buf, size_t len, Network_Addr *addr);
-typedef int net_send_cb(void *obj, int sock, const uint8_t *buf, size_t len);
-typedef int net_sendto_cb(void *obj, int sock, const uint8_t *buf, size_t len, const Network_Addr *addr);
-typedef int net_socket_cb(void *obj, int domain, int type, int proto);
-typedef int net_socket_nonblock_cb(void *obj, int sock, bool nonblock);
-typedef int net_getsockopt_cb(void *obj, int sock, int level, int optname, void *optval, size_t *optlen);
-typedef int net_setsockopt_cb(void *obj, int sock, int level, int optname, const void *optval, size_t optlen);
-typedef int net_getaddrinfo_cb(void *obj, int family, Network_Addr **addrs);
-typedef int net_freeaddrinfo_cb(void *obj, Network_Addr *addrs);
-
-/** @brief Functions wrapping POSIX network functions.
- *
- * Refer to POSIX man pages for documentation of what these functions are
- * expected to do when providing alternative Network implementations.
- */
-typedef struct Network_Funcs {
-    net_close_cb *close;
-    net_accept_cb *accept;
-    net_bind_cb *bind;
-    net_listen_cb *listen;
-    net_recvbuf_cb *recvbuf;
-    net_recv_cb *recv;
-    net_recvfrom_cb *recvfrom;
-    net_send_cb *send;
-    net_sendto_cb *sendto;
-    net_socket_cb *socket;
-    net_socket_nonblock_cb *socket_nonblock;
-    net_getsockopt_cb *getsockopt;
-    net_setsockopt_cb *setsockopt;
-    net_getaddrinfo_cb *getaddrinfo;
-    net_freeaddrinfo_cb *freeaddrinfo;
-} Network_Funcs;
-
-typedef struct Network {
-    const Network_Funcs *funcs;
-    void *obj;
-} Network;
-
-const Network *system_network(void);
-
 typedef struct Family {
     uint8_t value;
 } Family;
@@ -267,6 +217,8 @@ typedef struct Socket {
     int sock;
 } Socket;
 
+typedef Tox_Network Network;
+
 non_null()
 Socket net_socket(const Network *ns, Family domain, int type, int protocol);
 
@@ -560,7 +512,7 @@ void net_freeipport(const Memory *mem, IP_Port *ip_ports);
  * @return true on success, false on failure.
  */
 non_null()
-bool bind_to_port(const Network *ns, Socket sock, Family family, uint16_t port);
+bool bind_to_port(const Network *ns, const Memory *mem, Socket sock, Family family, uint16_t port);
 
 /** @brief Get the last networking error code.
  *
diff --git a/toxcore/onion.c b/toxcore/onion.c
index d7ec8bfd788..fafb21d0fb0 100644
--- a/toxcore/onion.c
+++ b/toxcore/onion.c
@@ -113,7 +113,7 @@ static int ipport_unpack(IP_Port *target, const uint8_t *data, unsigned int data
  * return -1 on failure.
  * return 0 on success.
  */
-int create_onion_path(const Random *rng, const DHT *dht, Onion_Path *new_path, const Node_format *nodes)
+int create_onion_path(const Tox_Random *rng, const DHT *dht, Onion_Path *new_path, const Node_format *nodes)
 {
     if (new_path == nullptr || nodes == nullptr) {
         return -1;
@@ -176,7 +176,7 @@ int onion_path_to_nodes(Node_format *nodes, unsigned int num_nodes, const Onion_
  * return -1 on failure.
  * return length of created packet on success.
  */
-int create_onion_packet(const Random *rng, uint8_t *packet, uint16_t max_packet_length,
+int create_onion_packet(const Tox_Random *rng, uint8_t *packet, uint16_t max_packet_length,
                         const Onion_Path *path, const IP_Port *dest,
                         const uint8_t *data, uint16_t length)
 {
@@ -236,7 +236,7 @@ int create_onion_packet(const Random *rng, uint8_t *packet, uint16_t max_packet_
  * return -1 on failure.
  * return length of created packet on success.
  */
-int create_onion_packet_tcp(const Random *rng, uint8_t *packet, uint16_t max_packet_length,
+int create_onion_packet_tcp(const Tox_Random *rng, uint8_t *packet, uint16_t max_packet_length,
                             const Onion_Path *path, const IP_Port *dest,
                             const uint8_t *data, uint16_t length)
 {
@@ -668,7 +668,7 @@ void set_callback_handle_recv_1(Onion *onion, onion_recv_1_cb *function, void *o
     onion->callback_object = object;
 }
 
-Onion *new_onion(const Logger *log, const Memory *mem, const Mono_Time *mono_time, const Random *rng, DHT *dht)
+Onion *new_onion(const Logger *log, const Memory *mem, const Mono_Time *mono_time, const Tox_Random *rng, DHT *dht)
 {
     if (dht == nullptr) {
         return nullptr;
diff --git a/toxcore/onion.h b/toxcore/onion.h
index 7f71c2493d3..93a472c21e7 100644
--- a/toxcore/onion.h
+++ b/toxcore/onion.h
@@ -19,7 +19,7 @@ typedef int onion_recv_1_cb(void *object, const IP_Port *dest, const uint8_t *da
 typedef struct Onion {
     const Logger *log;
     const Mono_Time *mono_time;
-    const Random *rng;
+    const Tox_Random *rng;
     const Memory *mem;
     DHT *dht;
     Networking_Core *net;
@@ -81,7 +81,7 @@ typedef struct Onion_Path {
  * return 0 on success.
  */
 non_null()
-int create_onion_path(const Random *rng, const DHT *dht, Onion_Path *new_path, const Node_format *nodes);
+int create_onion_path(const Tox_Random *rng, const DHT *dht, Onion_Path *new_path, const Node_format *nodes);
 
 /** @brief Dump nodes in onion path to nodes of length num_nodes.
  *
@@ -101,7 +101,7 @@ int onion_path_to_nodes(Node_format *nodes, unsigned int num_nodes, const Onion_
  * return length of created packet on success.
  */
 non_null()
-int create_onion_packet(const Random *rng, uint8_t *packet, uint16_t max_packet_length,
+int create_onion_packet(const Tox_Random *rng, uint8_t *packet, uint16_t max_packet_length,
                         const Onion_Path *path, const IP_Port *dest,
                         const uint8_t *data, uint16_t length);
 
@@ -116,7 +116,7 @@ int create_onion_packet(const Random *rng, uint8_t *packet, uint16_t max_packet_
  * return length of created packet on success.
  */
 non_null()
-int create_onion_packet_tcp(const Random *rng, uint8_t *packet, uint16_t max_packet_length,
+int create_onion_packet_tcp(const Tox_Random *rng, uint8_t *packet, uint16_t max_packet_length,
                             const Onion_Path *path, const IP_Port *dest,
                             const uint8_t *data, uint16_t length);
 
@@ -148,7 +148,7 @@ non_null(1) nullable(2, 3)
 void set_callback_handle_recv_1(Onion *onion, onion_recv_1_cb *function, void *object);
 
 non_null()
-Onion *new_onion(const Logger *log, const Memory *mem, const Mono_Time *mono_time, const Random *rng, DHT *dht);
+Onion *new_onion(const Logger *log, const Memory *mem, const Mono_Time *mono_time, const Tox_Random *rng, DHT *dht);
 
 nullable(1)
 void kill_onion(Onion *onion);
diff --git a/toxcore/onion_announce.c b/toxcore/onion_announce.c
index 551e7b1fae9..4c72000b474 100644
--- a/toxcore/onion_announce.c
+++ b/toxcore/onion_announce.c
@@ -50,7 +50,7 @@ typedef struct Onion_Announce_Entry {
 struct Onion_Announce {
     const Logger *log;
     const Mono_Time *mono_time;
-    const Random *rng;
+    const Tox_Random *rng;
     const Memory *mem;
     DHT     *dht;
     Networking_Core *net;
@@ -97,7 +97,7 @@ void onion_announce_entry_set_time(Onion_Announce *onion_a, uint32_t entry, uint
  * return -1 on failure.
  * return packet length on success.
  */
-int create_announce_request(const Random *rng, uint8_t *packet, uint16_t max_packet_length, const uint8_t *dest_client_id,
+int create_announce_request(const Tox_Random *rng, uint8_t *packet, uint16_t max_packet_length, const uint8_t *dest_client_id,
                             const uint8_t *public_key, const uint8_t *secret_key, const uint8_t *ping_id, const uint8_t *client_id,
                             const uint8_t *data_public_key, uint64_t sendback_data)
 {
@@ -140,7 +140,7 @@ int create_announce_request(const Random *rng, uint8_t *packet, uint16_t max_pac
  * return -1 on failure.
  * return 0 on success.
  */
-int create_data_request(const Random *rng, uint8_t *packet, uint16_t max_packet_length, const uint8_t *public_key,
+int create_data_request(const Tox_Random *rng, uint8_t *packet, uint16_t max_packet_length, const uint8_t *public_key,
                         const uint8_t *encrypt_public_key, const uint8_t *nonce, const uint8_t *data, uint16_t length)
 {
     if (DATA_REQUEST_MIN_SIZE + length > max_packet_length) {
@@ -186,7 +186,7 @@ int create_data_request(const Random *rng, uint8_t *packet, uint16_t max_packet_
  * return -1 on failure.
  * return 0 on success.
  */
-int send_announce_request(const Networking_Core *net, const Random *rng,
+int send_announce_request(const Networking_Core *net, const Tox_Random *rng,
                           const Onion_Path *path, const Node_format *dest,
                           const uint8_t *public_key, const uint8_t *secret_key,
                           const uint8_t *ping_id, const uint8_t *client_id,
@@ -230,7 +230,7 @@ int send_announce_request(const Networking_Core *net, const Random *rng,
  * return -1 on failure.
  * return 0 on success.
  */
-int send_data_request(const Networking_Core *net, const Random *rng, const Onion_Path *path, const IP_Port *dest,
+int send_data_request(const Networking_Core *net, const Tox_Random *rng, const Onion_Path *path, const IP_Port *dest,
                       const uint8_t *public_key, const uint8_t *encrypt_public_key, const uint8_t *nonce,
                       const uint8_t *data, uint16_t length)
 {
@@ -642,7 +642,7 @@ static int handle_data_request(void *object, const IP_Port *source, const uint8_
     return 0;
 }
 
-Onion_Announce *new_onion_announce(const Logger *log, const Memory *mem, const Random *rng, const Mono_Time *mono_time, DHT *dht)
+Onion_Announce *new_onion_announce(const Logger *log, const Memory *mem, const Tox_Random *rng, const Mono_Time *mono_time, DHT *dht)
 {
     if (dht == nullptr) {
         return nullptr;
diff --git a/toxcore/onion_announce.h b/toxcore/onion_announce.h
index 857f4706ace..97372e26f62 100644
--- a/toxcore/onion_announce.h
+++ b/toxcore/onion_announce.h
@@ -59,7 +59,7 @@ void onion_announce_entry_set_time(Onion_Announce *onion_a, uint32_t entry, uint
  * return packet length on success.
  */
 non_null()
-int create_announce_request(const Random *rng, uint8_t *packet, uint16_t max_packet_length, const uint8_t *dest_client_id,
+int create_announce_request(const Tox_Random *rng, uint8_t *packet, uint16_t max_packet_length, const uint8_t *dest_client_id,
                             const uint8_t *public_key, const uint8_t *secret_key, const uint8_t *ping_id, const uint8_t *client_id,
                             const uint8_t *data_public_key, uint64_t sendback_data);
 
@@ -76,7 +76,7 @@ int create_announce_request(const Random *rng, uint8_t *packet, uint16_t max_pac
  * return 0 on success.
  */
 non_null()
-int create_data_request(const Random *rng, uint8_t *packet, uint16_t max_packet_length, const uint8_t *public_key,
+int create_data_request(const Tox_Random *rng, uint8_t *packet, uint16_t max_packet_length, const uint8_t *public_key,
                         const uint8_t *encrypt_public_key, const uint8_t *nonce, const uint8_t *data, uint16_t length);
 
 /** @brief Create and send an onion announce request packet.
@@ -94,7 +94,7 @@ int create_data_request(const Random *rng, uint8_t *packet, uint16_t max_packet_
  * return 0 on success.
  */
 non_null()
-int send_announce_request(const Networking_Core *net, const Random *rng,
+int send_announce_request(const Networking_Core *net, const Tox_Random *rng,
                           const Onion_Path *path, const Node_format *dest,
                           const uint8_t *public_key, const uint8_t *secret_key,
                           const uint8_t *ping_id, const uint8_t *client_id,
@@ -117,7 +117,7 @@ int send_announce_request(const Networking_Core *net, const Random *rng,
  * return 0 on success.
  */
 non_null()
-int send_data_request(const Networking_Core *net, const Random *rng, const Onion_Path *path, const IP_Port *dest,
+int send_data_request(const Networking_Core *net, const Tox_Random *rng, const Onion_Path *path, const IP_Port *dest,
                       const uint8_t *public_key, const uint8_t *encrypt_public_key, const uint8_t *nonce,
                       const uint8_t *data, uint16_t length);
 
@@ -131,7 +131,7 @@ void onion_announce_extra_data_callback(Onion_Announce *onion_a, uint16_t extra_
                                         pack_extra_data_cb *extra_data_callback, void *extra_data_object);
 
 non_null()
-Onion_Announce *new_onion_announce(const Logger *log, const Memory *mem, const Random *rng, const Mono_Time *mono_time, DHT *dht);
+Onion_Announce *new_onion_announce(const Logger *log, const Memory *mem, const Tox_Random *rng, const Mono_Time *mono_time, DHT *dht);
 
 nullable(1)
 void kill_onion_announce(Onion_Announce *onion_a);
diff --git a/toxcore/onion_client.c b/toxcore/onion_client.c
index 6aef15ec3a8..8e46c16fab0 100644
--- a/toxcore/onion_client.c
+++ b/toxcore/onion_client.c
@@ -105,7 +105,7 @@ typedef struct Onion_Data_Handler {
 struct Onion_Client {
     const Mono_Time *mono_time;
     const Logger *logger;
-    const Random *rng;
+    const Tox_Random *rng;
     const Memory *mem;
 
     DHT     *dht;
@@ -2075,7 +2075,7 @@ void do_onion_client(Onion_Client *onion_c)
     onion_c->last_run = mono_time_get(onion_c->mono_time);
 }
 
-Onion_Client *new_onion_client(const Logger *logger, const Memory *mem, const Random *rng, const Mono_Time *mono_time, Net_Crypto *c)
+Onion_Client *new_onion_client(const Logger *logger, const Memory *mem, const Tox_Random *rng, const Mono_Time *mono_time, Net_Crypto *c)
 {
     if (c == nullptr) {
         return nullptr;
diff --git a/toxcore/onion_client.h b/toxcore/onion_client.h
index 6498f8c5c39..f6db95a6a51 100644
--- a/toxcore/onion_client.h
+++ b/toxcore/onion_client.h
@@ -208,7 +208,7 @@ non_null()
 void do_onion_client(Onion_Client *onion_c);
 
 non_null()
-Onion_Client *new_onion_client(const Logger *logger, const Memory *mem, const Random *rng, const Mono_Time *mono_time, Net_Crypto *c);
+Onion_Client *new_onion_client(const Logger *logger, const Memory *mem, const Tox_Random *rng, const Mono_Time *mono_time, Net_Crypto *c);
 
 nullable(1)
 void kill_onion_client(Onion_Client *onion_c);
diff --git a/toxcore/os_logger.c b/toxcore/os_logger.c
new file mode 100644
index 00000000000..8c425777a66
--- /dev/null
+++ b/toxcore/os_logger.c
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+#include "os_logger.h"
+
+#include "ccompat.h"
+#include "tox_logger_impl.h"
+
+non_null()
+static void os_logger_log(
+        void *self, Tox_Log_Level level,
+        const char *file, uint32_t line, const char *func,
+        const char *message)
+{
+    // Do nothing with the log message by default.
+    return;
+}
+
+static const Tox_Logger_Funcs os_logger_funcs = {
+    os_logger_log,
+};
+
+static const Tox_Logger os_logger_obj = {&os_logger_funcs};
+
+const Tox_Logger *os_logger(void)
+{
+    return &os_logger_obj;
+}
diff --git a/toxcore/os_logger.h b/toxcore/os_logger.h
new file mode 100644
index 00000000000..ff3b61100a8
--- /dev/null
+++ b/toxcore/os_logger.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_OS_LOGGER_H
+#define C_TOXCORE_TOXCORE_OS_LOGGER_H
+
+#include "tox_logger.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+const Tox_Logger *os_logger(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_OS_LOGGER_H
diff --git a/toxcore/os_memory.c b/toxcore/os_memory.c
new file mode 100644
index 00000000000..36fd5d3c540
--- /dev/null
+++ b/toxcore/os_memory.c
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+#include "os_memory.h"
+
+#include <stdlib.h>
+
+#include "ccompat.h"
+#include "tox_memory_impl.h"
+
+non_null()
+static void *os_malloc(void *self, uint32_t size)
+{
+    return malloc(size);
+}
+
+non_null()
+static void *os_calloc(void *self, uint32_t nmemb, uint32_t size)
+{
+    return calloc(nmemb, size);
+}
+
+non_null(1) nullable(2)
+static void *os_vrealloc(void *self, void *ptr, uint32_t nmemb, uint32_t size)
+{
+    const uint32_t bytes = nmemb * size;
+
+    if (size != 0 && bytes / size != nmemb) {
+        return nullptr;
+    }
+
+    return realloc(ptr, bytes);
+}
+
+non_null(1) nullable(2)
+static void os_free(void *self, void *ptr)
+{
+    free(ptr);
+}
+
+static const Tox_Memory_Funcs os_memory_funcs = {
+    os_malloc,
+    os_calloc,
+    os_vrealloc,
+    os_free,
+};
+static const Tox_Memory os_memory_obj = {&os_memory_funcs};
+
+const Tox_Memory *os_memory(void)
+{
+    return &os_memory_obj;
+}
diff --git a/toxcore/os_memory.h b/toxcore/os_memory.h
new file mode 100644
index 00000000000..8cd728e2399
--- /dev/null
+++ b/toxcore/os_memory.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_OS_MEMORY_H
+#define C_TOXCORE_TOXCORE_OS_MEMORY_H
+
+#include "tox_memory.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+const Tox_Memory *os_memory(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_OS_MEMORY_H
diff --git a/toxcore/os_network.c b/toxcore/os_network.c
new file mode 100644
index 00000000000..81ea6f57d37
--- /dev/null
+++ b/toxcore/os_network.c
@@ -0,0 +1,288 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+#ifdef __APPLE__
+#define _DARWIN_C_SOURCE
+#endif
+
+// For Solaris.
+#ifdef __sun
+#define __EXTENSIONS__ 1
+#endif
+
+// For Linux (and some BSDs).
+#ifndef _XOPEN_SOURCE
+#define _XOPEN_SOURCE 700
+#endif
+
+#if defined(_WIN32) && _WIN32_WINNT >= _WIN32_WINNT_WINXP
+#undef _WIN32_WINNT
+#define _WIN32_WINNT  0x501
+#endif
+
+#if !defined(OS_WIN32) && (defined(_WIN32) || defined(__WIN32__) || defined(WIN32))
+#define OS_WIN32
+#endif
+
+#if defined(OS_WIN32) && !defined(WINVER)
+// Windows XP
+#define WINVER 0x0501
+#endif
+
+#include "os_network.h"
+
+#ifdef OS_WIN32 // Put win32 includes here
+// The mingw32/64 Windows library warns about including winsock2.h after
+// windows.h even though with the above it's a valid thing to do. So, to make
+// mingw32 headers happy, we include winsock2.h first.
+#include <winsock2.h>
+// Comment line here to avoid reordering by source code formatters.
+#include <windows.h>
+#include <ws2tcpip.h>
+#endif
+
+#if !defined(OS_WIN32)
+#include <arpa/inet.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#ifdef __sun
+#include <stropts.h>
+#include <sys/filio.h>
+#endif
+
+#else
+#ifndef IPV6_V6ONLY
+#define IPV6_V6ONLY 27
+#endif
+#endif
+
+#include <assert.h>
+#include <string.h>  // memcpy
+
+#include "ccompat.h"
+#include "os_network_impl.h"
+#include "tox_network_impl.h"
+
+// Disable MSG_NOSIGNAL on systems not supporting it, e.g. Windows, FreeBSD
+#if !defined(MSG_NOSIGNAL)
+#define MSG_NOSIGNAL 0
+#endif
+
+non_null()
+static int os_close(void *self, int sock)
+{
+#if defined(OS_WIN32)
+    return closesocket(sock);
+#else  // !OS_WIN32
+    return close(sock);
+#endif
+}
+
+struct Network_Addr {
+    struct sockaddr_storage addr;
+    size_t size;
+};
+
+Network_Addr *net_addr_new(const void *data, size_t size, const Tox_Memory *mem)
+{
+    Network_Addr *addr = (Network_Addr *)tox_memory_calloc(mem, 1, sizeof(Network_Addr));
+
+    if (addr == nullptr) {
+        return nullptr;
+    }
+
+    if (data != nullptr) {
+        net_addr_set(addr, data, size);
+    } else {
+        addr->size = sizeof(struct sockaddr_storage);
+    }
+
+    return addr;
+}
+
+void net_addr_free(Network_Addr *addr, const Tox_Memory *mem)
+{
+    tox_memory_dealloc(mem, addr);
+}
+
+void net_addr_set(Network_Addr *addr, const void *data, size_t size)
+{
+    assert(size <= sizeof(struct sockaddr_storage));
+    memcpy(&addr->addr, data, size);
+    addr->size = size;
+}
+
+void *net_addr_mut_addr(Network_Addr *addr)
+{
+    return &addr->addr;
+}
+
+const void *net_addr_get_addr(const Network_Addr *addr)
+{
+    return &addr->addr;
+}
+
+void net_addr_set_size(Network_Addr *addr, size_t size)
+{
+    addr->size = size;
+}
+
+size_t net_addr_get_size(const Network_Addr *addr)
+{
+    return addr->size;
+}
+
+bool net_addr_is_ipv4(const Network_Addr *addr)
+{
+    return addr->addr.ss_family == AF_INET;
+}
+
+bool net_addr_is_ipv6(const Network_Addr *addr)
+{
+    return addr->addr.ss_family == AF_INET6;
+}
+
+uint16_t net_addr_get_port(const Network_Addr *addr)
+{
+    const int family = addr->addr.ss_family;
+    if (family == AF_INET6) {
+        const struct sockaddr_in6 *addr6 = (const struct sockaddr_in6 *)&addr->addr;
+        return addr6->sin6_port;
+    } else {
+        assert(family == AF_INET);
+        const struct sockaddr_in *addr4 = (const struct sockaddr_in *)&addr->addr;
+        return addr4->sin_port;
+    }
+}
+
+
+non_null()
+static int os_accept(void *self, int sock)
+{
+    return accept(sock, nullptr, nullptr);
+}
+
+non_null()
+static int os_bind(void *self, int sock, const Network_Addr *addr)
+{
+    return bind(sock, (const struct sockaddr *)net_addr_get_addr(addr), net_addr_get_size(addr));
+}
+
+non_null()
+static int os_listen(void *self, int sock, int backlog)
+{
+    return listen(sock, backlog);
+}
+
+non_null()
+static int os_recvbuf(void *self, int sock)
+{
+#ifdef OS_WIN32
+    u_long count = 0;
+    ioctlsocket(sock, FIONREAD, &count);
+#else
+    int count = 0;
+    ioctl(sock, FIONREAD, &count);
+#endif
+
+    return count;
+}
+
+non_null()
+static int os_recv(void *self, int sock, uint8_t *buf, size_t len)
+{
+    return recv(sock, (char *)buf, len, MSG_NOSIGNAL);
+}
+
+non_null()
+static int os_send(void *self, int sock, const uint8_t *buf, size_t len)
+{
+    return send(sock, (const char *)buf, len, MSG_NOSIGNAL);
+}
+
+non_null()
+static int os_sendto(void *self, int sock, const uint8_t *buf, size_t len, const Network_Addr *addr) {
+    return sendto(sock, (const char *)buf, len, 0, (const struct sockaddr *)&addr->addr, addr->size);
+}
+
+non_null()
+static int os_recvfrom(void *self, int sock, uint8_t *buf, size_t len, Network_Addr *addr) {
+    socklen_t size = addr->size;
+    const int ret = recvfrom(sock, (char *)buf, len, 0, (struct sockaddr *)&addr->addr, &size);
+    addr->size = size;
+    return ret;
+}
+
+non_null()
+static int os_socket(void *self, int domain, int type, int proto)
+{
+    return (int)socket(domain, type, proto);
+}
+
+non_null()
+static int os_socket_nonblock(void *self, int sock, bool nonblock)
+{
+#ifdef OS_WIN32
+    u_long mode = nonblock ? 1 : 0;
+    return ioctlsocket(sock, FIONBIO, &mode);
+#else
+    return fcntl(sock, F_SETFL, O_NONBLOCK, nonblock ? 1 : 0);
+#endif /* OS_WIN32 */
+}
+
+non_null()
+static int os_getsockopt(void *self, int sock, int level, int optname, void *optval, size_t *optlen)
+{
+    socklen_t len = *optlen;
+    const int ret = getsockopt(sock, level, optname, optval, &len);
+    *optlen = len;
+    return ret;
+}
+
+non_null()
+static int os_setsockopt(void *self, int sock, int level, int optname, const void *optval, size_t optlen)
+{
+    return setsockopt(sock, level, optname, optval, optlen);
+}
+
+static const Tox_Network_Funcs os_network_funcs = {
+    os_close,
+    os_accept,
+    os_bind,
+    os_listen,
+    os_recvbuf,
+    os_recv,
+    os_recvfrom,
+    os_send,
+    os_sendto,
+    os_socket,
+    os_socket_nonblock,
+    os_getsockopt,
+    os_setsockopt,
+};
+static const Tox_Network os_network_obj = {&os_network_funcs};
+
+const Tox_Network *os_network(void)
+{
+#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+    if ((true)) {
+        return nullptr;
+    }
+#endif
+#ifdef OS_WIN32
+    WSADATA wsaData;
+
+    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != NO_ERROR) {
+        return nullptr;
+    }
+#endif
+    return &os_network_obj;
+}
diff --git a/toxcore/os_network.h b/toxcore/os_network.h
new file mode 100644
index 00000000000..fd144e65917
--- /dev/null
+++ b/toxcore/os_network.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_OS_NETWORK_H
+#define C_TOXCORE_TOXCORE_OS_NETWORK_H
+
+#include "tox_network.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+const Tox_Network *os_network(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_OS_NETWORK_H
diff --git a/toxcore/os_network_impl.h b/toxcore/os_network_impl.h
new file mode 100644
index 00000000000..26cacf6b410
--- /dev/null
+++ b/toxcore/os_network_impl.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_OS_NETWORK_IMPL_H
+#define C_TOXCORE_TOXCORE_OS_NETWORK_IMPL_H
+
+#include "tox_network.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+non_null() Network_Addr *net_addr_new(const void *data, size_t size, const Tox_Memory *mem);
+non_null() void net_addr_free(Network_Addr *addr, const Tox_Memory *mem);
+
+non_null() void net_addr_set(Network_Addr *addr, const void *data, size_t size);
+
+non_null() void *net_addr_mut_addr(Network_Addr *addr);
+non_null() const void *net_addr_get_addr(const Network_Addr *addr);
+
+non_null() void net_addr_set_size(Network_Addr *addr, size_t size);
+non_null() size_t net_addr_get_size(const Network_Addr *addr);
+
+non_null() bool net_addr_is_ipv4(const Network_Addr *addr);
+non_null() bool net_addr_is_ipv6(const Network_Addr *addr);
+
+non_null() uint16_t net_addr_get_port(const Network_Addr *addr);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_OS_NETWORK_IMPL_H
diff --git a/toxcore/os_random.c b/toxcore/os_random.c
new file mode 100644
index 00000000000..66a8c5244a7
--- /dev/null
+++ b/toxcore/os_random.c
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+#include "os_random.h"
+
+#ifndef VANILLA_NACL
+// We use libsodium by default.
+#include <sodium.h>
+#else
+#include <randombytes.h>
+#endif
+
+#include "ccompat.h"
+#include "tox_random_impl.h"
+
+non_null()
+static void os_random_bytes(void *self, uint8_t *bytes, uint32_t length)
+{
+    randombytes(bytes, length);
+}
+
+non_null()
+static uint32_t os_random_uniform(void *self, uint32_t upper_bound)
+{
+#ifdef VANILLA_NACL
+    if (upper_bound == 0) {
+        return 0;
+    }
+
+    uint32_t randnum;
+    os_random_bytes(self, (uint8_t *)&randnum, sizeof(randnum));
+    return randnum % upper_bound;
+#else
+    return randombytes_uniform(upper_bound);
+#endif
+}
+
+static const Tox_Random_Funcs os_random_funcs = {
+    os_random_bytes,
+    os_random_uniform,
+};
+
+static const Tox_Random os_random_obj = {&os_random_funcs};
+
+const Tox_Random *os_random(void)
+{
+#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+    if ((true)) {
+        return nullptr;
+    }
+#endif
+#ifndef VANILLA_NACL
+    // It is safe to call this function more than once and from different
+    // threads -- subsequent calls won't have any effects.
+    if (sodium_init() == -1) {
+        return nullptr;
+    }
+#endif
+    return &os_random_obj;
+}
diff --git a/toxcore/os_random.h b/toxcore/os_random.h
new file mode 100644
index 00000000000..d265a2d26d4
--- /dev/null
+++ b/toxcore/os_random.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_OS_RANDOM_H
+#define C_TOXCORE_TOXCORE_OS_RANDOM_H
+
+#include "tox_random.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+const Tox_Random *os_random(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_OS_RANDOM_H
diff --git a/toxcore/os_system.c b/toxcore/os_system.c
new file mode 100644
index 00000000000..f79edbc2002
--- /dev/null
+++ b/toxcore/os_system.c
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+#include "os_system.h"
+
+#include "ccompat.h"
+#include "os_logger.h"
+#include "os_memory.h"
+#include "os_network.h"
+#include "os_random.h"
+#include "tox_system_impl.h"
+
+Tox_System os_system(const Tox_Logger *log, const Tox_Memory *mem, const Tox_Network *ns, const Tox_Random *rng, const Tox_Time *tm)
+{
+    const Tox_System sys = {
+        log != nullptr ? log : os_logger(),
+        mem != nullptr ? mem : os_memory(),
+        ns != nullptr ? ns : os_network(),
+        rng != nullptr ? rng : os_random(),
+        tm, // no os_time, mono_time has it.
+    };
+
+    return sys;
+}
diff --git a/toxcore/os_system.h b/toxcore/os_system.h
new file mode 100644
index 00000000000..c3fe96262ca
--- /dev/null
+++ b/toxcore/os_system.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_OS_SYSTEM_H
+#define C_TOXCORE_TOXCORE_OS_SYSTEM_H
+
+#include "tox_system.h"
+#include "tox_system_impl.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** @brief Default operating-system-backed `Tox_System`.
+ *
+ * If any of the parameters are NULL, they are set to the OS instance of that
+ * subsystem. Only `Tox_Time` does not have a subsystem here, and instead is
+ * created in `mono_time`.
+ *
+ * This function, and by extension all the subsystem functions, does not
+ * allocate any dynamic memory.
+ */
+nullable(1, 2, 3, 4, 5)
+Tox_System os_system(const Tox_Logger *log, const Tox_Memory *mem, const Tox_Network *ns, const Tox_Random *rng, const Tox_Time *tm);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_OS_SYSTEM_H
diff --git a/toxcore/ping.c b/toxcore/ping.c
index f8a96edfb96..48d6babdae5 100644
--- a/toxcore/ping.c
+++ b/toxcore/ping.c
@@ -30,7 +30,7 @@
 
 struct Ping {
     const Mono_Time *mono_time;
-    const Random *rng;
+    const Tox_Random *rng;
     DHT *dht;
 
     Ping_Array  *ping_array;
@@ -336,7 +336,7 @@ void ping_iterate(Ping *ping)
 }
 
 
-Ping *ping_new(const Memory *mem, const Mono_Time *mono_time, const Random *rng, DHT *dht)
+Ping *ping_new(const Memory *mem, const Mono_Time *mono_time, const Tox_Random *rng, DHT *dht)
 {
     Ping *ping = (Ping *)mem_alloc(mem, sizeof(Ping));
 
diff --git a/toxcore/ping.h b/toxcore/ping.h
index c5613459916..ee2d1d8cbac 100644
--- a/toxcore/ping.h
+++ b/toxcore/ping.h
@@ -18,7 +18,7 @@
 typedef struct Ping Ping;
 
 non_null()
-Ping *ping_new(const Memory *mem, const Mono_Time *mono_time, const Random *rng, DHT *dht);
+Ping *ping_new(const Memory *mem, const Mono_Time *mono_time, const Tox_Random *rng, DHT *dht);
 
 non_null(1) nullable(2)
 void ping_kill(const Memory *mem, Ping *ping);
diff --git a/toxcore/ping_array.c b/toxcore/ping_array.c
index f303d802158..f475fb161dc 100644
--- a/toxcore/ping_array.c
+++ b/toxcore/ping_array.c
@@ -105,7 +105,7 @@ static void ping_array_clear_timedout(Ping_Array *array, const Mono_Time *mono_t
     }
 }
 
-uint64_t ping_array_add(Ping_Array *array, const Mono_Time *mono_time, const Random *rng,
+uint64_t ping_array_add(Ping_Array *array, const Mono_Time *mono_time, const Tox_Random *rng,
                         const uint8_t *data, uint32_t length)
 {
     ping_array_clear_timedout(array, mono_time);
diff --git a/toxcore/ping_array.h b/toxcore/ping_array.h
index 5fc04017357..cdadcfe4b40 100644
--- a/toxcore/ping_array.h
+++ b/toxcore/ping_array.h
@@ -45,7 +45,7 @@ void ping_array_kill(Ping_Array *array);
  * @return ping_id on success, 0 on failure.
  */
 non_null()
-uint64_t ping_array_add(Ping_Array *array, const Mono_Time *mono_time, const Random *rng,
+uint64_t ping_array_add(Ping_Array *array, const Mono_Time *mono_time, const Tox_Random *rng,
                         const uint8_t *data, uint32_t length);
 
 /**
diff --git a/toxcore/ping_array_test.cc b/toxcore/ping_array_test.cc
index 8ce557092e4..1924de0f39d 100644
--- a/toxcore/ping_array_test.cc
+++ b/toxcore/ping_array_test.cc
@@ -5,6 +5,8 @@
 #include <memory>
 
 #include "mono_time.h"
+#include "os_memory.h"
+#include "os_random.h"
 
 namespace {
 
@@ -29,21 +31,21 @@ using Mono_Time_Ptr = std::unique_ptr<Mono_Time, Mono_Time_Deleter>;
 
 TEST(PingArray, MinimumTimeoutIsOne)
 {
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     EXPECT_EQ(ping_array_new(mem, 1, 0), nullptr);
     EXPECT_NE(Ping_Array_Ptr(ping_array_new(mem, 1, 1)), nullptr);
 }
 
 TEST(PingArray, MinimumArraySizeIsOne)
 {
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
     EXPECT_EQ(ping_array_new(mem, 0, 1), nullptr);
     EXPECT_NE(Ping_Array_Ptr(ping_array_new(mem, 1, 1)), nullptr);
 }
 
 TEST(PingArray, ArraySizeMustBePowerOfTwo)
 {
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
 
     Ping_Array_Ptr arr;
     arr.reset(ping_array_new(mem, 2, 1));
@@ -59,12 +61,12 @@ TEST(PingArray, ArraySizeMustBePowerOfTwo)
 
 TEST(PingArray, StoredDataCanBeRetrieved)
 {
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
 
     Ping_Array_Ptr const arr(ping_array_new(mem, 2, 1));
-    Mono_Time_Ptr const mono_time(mono_time_new(mem, nullptr, nullptr), mem);
+    Mono_Time_Ptr const mono_time(mono_time_new(mem, nullptr), mem);
     ASSERT_NE(mono_time, nullptr);
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
 
     uint64_t const ping_id = ping_array_add(
@@ -78,12 +80,12 @@ TEST(PingArray, StoredDataCanBeRetrieved)
 
 TEST(PingArray, RetrievingDataWithTooSmallOutputBufferHasNoEffect)
 {
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
 
     Ping_Array_Ptr const arr(ping_array_new(mem, 2, 1));
-    Mono_Time_Ptr const mono_time(mono_time_new(mem, nullptr, nullptr), mem);
+    Mono_Time_Ptr const mono_time(mono_time_new(mem, nullptr), mem);
     ASSERT_NE(mono_time, nullptr);
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
 
     uint64_t const ping_id = ping_array_add(
@@ -101,12 +103,12 @@ TEST(PingArray, RetrievingDataWithTooSmallOutputBufferHasNoEffect)
 
 TEST(PingArray, ZeroLengthDataCanBeAdded)
 {
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
 
     Ping_Array_Ptr const arr(ping_array_new(mem, 2, 1));
-    Mono_Time_Ptr const mono_time(mono_time_new(mem, nullptr, nullptr), mem);
+    Mono_Time_Ptr const mono_time(mono_time_new(mem, nullptr), mem);
     ASSERT_NE(mono_time, nullptr);
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
 
     uint8_t c = 0;
@@ -118,10 +120,10 @@ TEST(PingArray, ZeroLengthDataCanBeAdded)
 
 TEST(PingArray, PingId0IsInvalid)
 {
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
 
     Ping_Array_Ptr const arr(ping_array_new(mem, 2, 1));
-    Mono_Time_Ptr const mono_time(mono_time_new(mem, nullptr, nullptr), mem);
+    Mono_Time_Ptr const mono_time(mono_time_new(mem, nullptr), mem);
     ASSERT_NE(mono_time, nullptr);
 
     uint8_t c = 0;
@@ -131,12 +133,12 @@ TEST(PingArray, PingId0IsInvalid)
 // Protection against replay attacks.
 TEST(PingArray, DataCanOnlyBeRetrievedOnce)
 {
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
 
     Ping_Array_Ptr const arr(ping_array_new(mem, 2, 1));
-    Mono_Time_Ptr const mono_time(mono_time_new(mem, nullptr, nullptr), mem);
+    Mono_Time_Ptr const mono_time(mono_time_new(mem, nullptr), mem);
     ASSERT_NE(mono_time, nullptr);
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
 
     uint8_t c = 0;
@@ -149,12 +151,12 @@ TEST(PingArray, DataCanOnlyBeRetrievedOnce)
 
 TEST(PingArray, PingIdMustMatchOnCheck)
 {
-    const Memory *mem = system_memory();
+    const Memory *mem = os_memory();
 
     Ping_Array_Ptr const arr(ping_array_new(mem, 1, 1));
-    Mono_Time_Ptr const mono_time(mono_time_new(mem, nullptr, nullptr), mem);
+    Mono_Time_Ptr const mono_time(mono_time_new(mem, nullptr), mem);
     ASSERT_NE(mono_time, nullptr);
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
 
     uint8_t c = 0;
diff --git a/toxcore/tox.c b/toxcore/tox.c
index d17e61b70f2..c61c3c9fdd6 100644
--- a/toxcore/tox.c
+++ b/toxcore/tox.c
@@ -25,6 +25,7 @@
 #include "mem.h"
 #include "mono_time.h"
 #include "network.h"
+#include "os_system.h"
 #include "tox_private.h"
 #include "tox_struct.h"
 
@@ -649,7 +650,7 @@ Tox *tox_new(const struct Tox_Options *options, Tox_Err_New *error)
     assert(opts != nullptr);
 
     const Tox_System *sys = tox_options_get_operating_system(opts);
-    const Tox_System default_system = tox_default_system();
+    const Tox_System default_system = os_system(nullptr, nullptr, nullptr, nullptr, nullptr);
 
     if (sys == nullptr) {
         sys = &default_system;
@@ -777,7 +778,7 @@ Tox *tox_new(const struct Tox_Options *options, Tox_Err_New *error)
         m_options.proxy_info.ip_port.port = net_htons(tox_options_get_proxy_port(opts));
     }
 
-    tox->mono_time = mono_time_new(tox->sys.mem, sys->mono_time_callback, sys->mono_time_user_data);
+    tox->mono_time = mono_time_new(tox->sys.mem, sys->tm);
 
     if (tox->mono_time == nullptr) {
         SET_ERROR_PARAMETER(error, TOX_ERR_NEW_MALLOC);
diff --git a/toxcore/tox.h b/toxcore/tox.h
index d03e2b19b9b..f5fd4239f68 100644
--- a/toxcore/tox.h
+++ b/toxcore/tox.h
@@ -104,6 +104,8 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "tox_system.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -445,42 +447,8 @@ typedef enum Tox_Savedata_Type {
 
 } Tox_Savedata_Type;
 
-
-/**
- * @brief Severity level of log messages.
- */
-typedef enum Tox_Log_Level {
-
-    /**
-     * Very detailed traces including all network activity.
-     */
-    TOX_LOG_LEVEL_TRACE,
-
-    /**
-     * Debug messages such as which port we bind to.
-     */
-    TOX_LOG_LEVEL_DEBUG,
-
-    /**
-     * Informational log messages such as video call status changes.
-     */
-    TOX_LOG_LEVEL_INFO,
-
-    /**
-     * Warnings about events_alloc inconsistency or logic errors.
-     */
-    TOX_LOG_LEVEL_WARNING,
-
-    /**
-     * Severe unexpected errors caused by external or events_alloc inconsistency.
-     */
-    TOX_LOG_LEVEL_ERROR,
-
-} Tox_Log_Level;
-
-
 /**
- * @brief This event is triggered when the toxcore library logs an events_alloc message.
+ * @brief This event is triggered when the toxcore library logs a message.
  *
  * This is mostly useful for debugging. This callback can be called from any
  * function, not just tox_iterate. This means the user data lifetime must at
@@ -500,17 +468,6 @@ typedef enum Tox_Log_Level {
 typedef void tox_log_cb(Tox *tox, Tox_Log_Level level, const char *file, uint32_t line, const char *func,
                         const char *message, void *user_data);
 
-
-/**
- * @brief Operating system functions used by Tox.
- *
- * This struct is opaque and generally shouldn't be used in clients, but in
- * combination with tox_private.h, it allows tests to inject non-IO (hermetic)
- * versions of low level network, RNG, and time keeping functions.
- */
-typedef struct Tox_System Tox_System;
-
-
 /**
  * @brief This struct contains all the startup options for Tox.
  *
diff --git a/toxcore/tox_api.c b/toxcore/tox_api.c
index 61c248c30d7..3163ff308c0 100644
--- a/toxcore/tox_api.c
+++ b/toxcore/tox_api.c
@@ -161,7 +161,7 @@ ACCESSORS(void *, log_, user_data)
 ACCESSORS(bool,, local_discovery_enabled)
 ACCESSORS(bool,, dht_announcements_enabled)
 ACCESSORS(bool,, experimental_thread_safety)
-ACCESSORS(const Tox_System *,, operating_system)
+ACCESSORS(const struct Tox_System *,, operating_system)
 
 //!TOKSTYLE+
 
diff --git a/toxcore/tox_attributes.h b/toxcore/tox_attributes.h
new file mode 100644
index 00000000000..7200763a883
--- /dev/null
+++ b/toxcore/tox_attributes.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+/**
+ * printf and nonnull attributes for GCC/Clang and Cimple.
+ */
+#ifndef C_TOXCORE_TOXCORE_TOX_ATTRIBUTES_H
+#define C_TOXCORE_TOXCORE_TOX_ATTRIBUTES_H
+
+/* No declarations here. */
+
+//!TOKSTYLE-
+
+#ifdef __GNUC__
+#define GNU_PRINTF(f, a) __attribute__((__format__(__printf__, f, a)))
+#else
+#define GNU_PRINTF(f, a)
+#endif
+
+#if defined(__GNUC__) && defined(_DEBUG) && !defined(__OPTIMIZE__)
+#define non_null(...) __attribute__((__nonnull__(__VA_ARGS__)))
+#else
+#define non_null(...)
+#endif
+
+#define nullable(...)
+
+//!TOKSTYLE+
+
+#endif // C_TOXCORE_TOXCORE_TOX_ATTRIBUTES_H
diff --git a/toxcore/tox_events.c b/toxcore/tox_events.c
index cae662e58ef..490c1b6871f 100644
--- a/toxcore/tox_events.c
+++ b/toxcore/tox_events.c
@@ -14,7 +14,7 @@
 #include "events/events_alloc.h"
 #include "mem.h"
 #include "tox.h"
-#include "tox_private.h"
+#include "tox_system_impl.h"
 
 
 /*****************************************************
diff --git a/toxcore/tox_events.h b/toxcore/tox_events.h
index e868d89098a..8a0cd8a7d8d 100644
--- a/toxcore/tox_events.h
+++ b/toxcore/tox_events.h
@@ -343,9 +343,9 @@ void tox_events_free(Tox_Events *events);
 uint32_t tox_events_bytes_size(const Tox_Events *events);
 void tox_events_get_bytes(const Tox_Events *events, uint8_t *bytes);
 
-Tox_Events *tox_events_load(const Tox_System *sys, const uint8_t *bytes, uint32_t bytes_size);
+Tox_Events *tox_events_load(const struct Tox_System *sys, const uint8_t *bytes, uint32_t bytes_size);
 
-bool tox_events_equal(const Tox_System *sys, const Tox_Events *a, const Tox_Events *b);
+bool tox_events_equal(const struct Tox_System *sys, const Tox_Events *a, const Tox_Events *b);
 
 #ifdef __cplusplus
 }
diff --git a/toxcore/tox_events_test.cc b/toxcore/tox_events_test.cc
index 5de29b5e483..0c58e20323d 100644
--- a/toxcore/tox_events_test.cc
+++ b/toxcore/tox_events_test.cc
@@ -6,13 +6,15 @@
 #include <vector>
 
 #include "crypto_core.h"
+#include "os_system.h"
 #include "tox_private.h"
+#include "tox_system_impl.h"
 
 namespace {
 
 TEST(ToxEvents, UnpackRandomDataDoesntCrash)
 {
-    const Tox_System sys = tox_default_system();
+    const Tox_System sys = os_system(nullptr, nullptr, nullptr, nullptr, nullptr);
     ASSERT_NE(sys.rng, nullptr);
     std::array<uint8_t, 128> data;
     random_bytes(sys.rng, data.data(), data.size());
@@ -21,7 +23,7 @@ TEST(ToxEvents, UnpackRandomDataDoesntCrash)
 
 TEST(ToxEvents, UnpackEmptyDataFails)
 {
-    const Tox_System sys = tox_default_system();
+    const Tox_System sys = os_system(nullptr, nullptr, nullptr, nullptr, nullptr);
     std::array<uint8_t, 1> data;
     Tox_Events *events = tox_events_load(&sys, data.end(), 0);
     EXPECT_EQ(events, nullptr);
@@ -29,7 +31,7 @@ TEST(ToxEvents, UnpackEmptyDataFails)
 
 TEST(ToxEvents, UnpackEmptyArrayCreatesEmptyEvents)
 {
-    const Tox_System sys = tox_default_system();
+    const Tox_System sys = os_system(nullptr, nullptr, nullptr, nullptr, nullptr);
     std::array<uint8_t, 1> data{0x90};  // empty msgpack array
     Tox_Events *events = tox_events_load(&sys, data.data(), data.size());
     ASSERT_NE(events, nullptr);
@@ -47,7 +49,7 @@ TEST(ToxEvents, NullEventsPacksToEmptyArray)
 
 TEST(ToxEvents, PackedEventsCanBeUnpacked)
 {
-    const Tox_System sys = tox_default_system();
+    const Tox_System sys = os_system(nullptr, nullptr, nullptr, nullptr, nullptr);
     // [[0, 1]] == Tox_Self_Connection_Status { .connection_status = TOX_CONNECTION_TCP }
     std::array<uint8_t, 6> packed{0x91, 0x92, 0xcc, 0x00, 0xcc, 0x01};
     Tox_Events *events = tox_events_load(&sys, packed.data(), packed.size());
@@ -61,7 +63,7 @@ TEST(ToxEvents, PackedEventsCanBeUnpacked)
 
 TEST(ToxEvents, DealsWithHugeMsgpackArrays)
 {
-    const Tox_System sys = tox_default_system();
+    const Tox_System sys = os_system(nullptr, nullptr, nullptr, nullptr, nullptr);
     std::vector<uint8_t> data{0xdd, 0xff, 0xff, 0xff, 0xff};
     EXPECT_EQ(tox_events_load(&sys, data.data(), data.size()), nullptr);
 }
diff --git a/toxcore/tox_logger.c b/toxcore/tox_logger.c
new file mode 100644
index 00000000000..0a9f8034a4f
--- /dev/null
+++ b/toxcore/tox_logger.c
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+#include "tox_logger.h"
+
+#include "ccompat.h"
+#include "tox_logger_impl.h"
+
+Tox_Logger *tox_logger_new(const Tox_Logger_Funcs *funcs, void *user_data, const Tox_Memory *mem)
+{
+    Tox_Logger *log = (Tox_Logger *)tox_memory_calloc(mem, 1, sizeof(Tox_Logger));
+
+    if (log == nullptr) {
+        return nullptr;
+    }
+
+    log->funcs = funcs;
+    log->user_data = user_data;
+
+    log->mem = mem;
+
+    return log;
+}
+
+void tox_logger_free(Tox_Logger *log)
+{
+    tox_memory_dealloc(log->mem, log);
+}
+
+void tox_logger_log(
+        const Tox_Logger *log, Tox_Log_Level level,
+        const char *file, uint32_t line, const char *func,
+        const char *message)
+{
+    log->funcs->log_callback(log->user_data, level, file, line, func, message);
+}
diff --git a/toxcore/tox_logger.h b/toxcore/tox_logger.h
new file mode 100644
index 00000000000..015aca55e64
--- /dev/null
+++ b/toxcore/tox_logger.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_TOX_LOGGER_H
+#define C_TOXCORE_TOXCORE_TOX_LOGGER_H
+
+#include "tox_memory.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Severity level of log messages.
+ */
+typedef enum Tox_Log_Level {
+
+    /**
+     * Very detailed traces including all network activity.
+     */
+    TOX_LOG_LEVEL_TRACE,
+
+    /**
+     * Debug messages such as which port we bind to.
+     */
+    TOX_LOG_LEVEL_DEBUG,
+
+    /**
+     * Informational log messages such as video call status changes.
+     */
+    TOX_LOG_LEVEL_INFO,
+
+    /**
+     * Warnings about events_alloc inconsistency or logic errors.
+     */
+    TOX_LOG_LEVEL_WARNING,
+
+    /**
+     * Severe unexpected errors caused by external or events_alloc inconsistency.
+     */
+    TOX_LOG_LEVEL_ERROR,
+
+} Tox_Log_Level;
+
+
+typedef struct Tox_Logger_Funcs Tox_Logger_Funcs;
+
+typedef struct Tox_Logger Tox_Logger;
+
+non_null(1, 3) nullable(2)
+Tox_Logger *tox_logger_new(const Tox_Logger_Funcs *funcs, void *user_data, const Tox_Memory *mem);
+
+nullable(1) void tox_logger_free(Tox_Logger *log);
+
+non_null() void tox_logger_log(
+        const Tox_Logger *log, Tox_Log_Level level,
+        const char *file, uint32_t line, const char *func,
+        const char *message);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_TOX_LOGGER_H
diff --git a/toxcore/tox_logger_impl.h b/toxcore/tox_logger_impl.h
new file mode 100644
index 00000000000..9d3795a91ac
--- /dev/null
+++ b/toxcore/tox_logger_impl.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_TOX_LOGGER_IMPL_H
+#define C_TOXCORE_TOXCORE_TOX_LOGGER_IMPL_H
+
+#include "tox_logger.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief This event is triggered when the toxcore library logs a message.
+ *
+ * This is mostly useful for debugging. This callback can be called from any
+ * function, not just tox_iterate. This means the user data lifetime must at
+ * least extend between registering and unregistering it or tox_kill.
+ *
+ * Other toxcore modules such as toxav may concurrently call this callback at
+ * any time. Thus, user code must make sure it is equipped to handle concurrent
+ * execution, e.g. by employing appropriate mutex locking.
+ *
+ * @param self The user data pointer passed to `tox_logger_new`.
+ * @param level The severity of the log message.
+ * @param file The source file from which the message originated.
+ * @param line The source line from which the message originated.
+ * @param func The function from which the message originated.
+ * @param message The log message.
+ */
+typedef void tox_logger_log_cb(
+        void *self, Tox_Log_Level level,
+        const char *file, uint32_t line, const char *func,
+        const char *message);
+
+
+struct Tox_Logger_Funcs {
+    tox_logger_log_cb *log_callback;
+};
+
+struct Tox_Logger {
+    const Tox_Logger_Funcs *funcs;
+    void *user_data;
+
+    const Tox_Memory *mem;
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_TOX_LOGGER_IMPL_H
diff --git a/toxcore/tox_memory.c b/toxcore/tox_memory.c
new file mode 100644
index 00000000000..8c31fb089bf
--- /dev/null
+++ b/toxcore/tox_memory.c
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2016-2018 The TokTok team.
+ * Copyright © 2013 Tox project.
+ */
+#include "tox_memory.h"
+
+#include "ccompat.h"
+#include "tox_memory_impl.h"
+
+Tox_Memory *tox_memory_new(const Tox_Memory_Funcs *funcs, void *user_data)
+{
+    const Tox_Memory bootstrap = {funcs, user_data};
+
+    Tox_Memory *mem = tox_memory_calloc(&bootstrap, 1, sizeof(Tox_Memory));
+
+    if (mem == nullptr) {
+        return nullptr;
+    }
+
+    *mem = bootstrap;
+
+    return mem;
+}
+
+void tox_memory_free(Tox_Memory *mem)
+{
+    if (mem == nullptr) {
+        return;
+    }
+
+    tox_memory_dealloc(mem, mem);
+}
+
+void *tox_memory_malloc(const Tox_Memory *mem, uint32_t size)
+{
+    void *const ptr = mem->funcs->malloc_callback(mem->user_data, size);
+    return ptr;
+}
+
+void *tox_memory_calloc(const Tox_Memory *mem, uint32_t nmemb, uint32_t size)
+{
+    void *const ptr = mem->funcs->calloc_callback(mem->user_data, nmemb, size);
+    return ptr;
+}
+
+void *tox_memory_vrealloc(const Tox_Memory *mem, void *ptr, uint32_t nmemb, uint32_t size)
+{
+    void *const new_ptr = mem->funcs->realloc_callback(mem->user_data, ptr, nmemb, size);
+    return new_ptr;
+}
+
+void tox_memory_dealloc(const Tox_Memory *mem, void *ptr)
+{
+    mem->funcs->dealloc_callback(mem->user_data, ptr);
+}
diff --git a/toxcore/tox_memory.h b/toxcore/tox_memory.h
new file mode 100644
index 00000000000..9185f1f6e57
--- /dev/null
+++ b/toxcore/tox_memory.h
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2016-2018 The TokTok team.
+ * Copyright © 2013 Tox project.
+ */
+
+/**
+ * Memory allocation and deallocation functions.
+ */
+#ifndef C_TOXCORE_TOXCORE_TOX_MEMORY_H
+#define C_TOXCORE_TOXCORE_TOX_MEMORY_H
+
+#include <stdint.h>     // uint*_t
+
+#include "tox_attributes.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** @brief Functions wrapping standard C memory allocation functions. */
+typedef struct Tox_Memory_Funcs Tox_Memory_Funcs;
+
+/**
+ * @brief A dynamic memory allocator.
+ */
+typedef struct Tox_Memory Tox_Memory;
+
+/**
+ * @brief Allocates a new allocator using itself to allocate its own memory.
+ *
+ * The passed `user_data` is stored and passed to allocator callbacks. It must
+ * outlive the `Tox_Memory` object, since it may be used by the callback invoked
+ * in `tox_memory_free`.
+ *
+ * @return NULL if allocation fails.
+ */
+non_null(1) nullable(2)
+Tox_Memory *tox_memory_new(const Tox_Memory_Funcs *funcs, void *user_data);
+
+/**
+ * @brief Destroys the allocator using its own deallocation function.
+ *
+ * The stored `user_data` will not be deallocated.
+ */
+nullable(1) void tox_memory_free(Tox_Memory *mem);
+
+/**
+ * @brief Allocate an array of a given size for built-in types.
+ *
+ * The array will not be initialised. Supported built-in types are
+ * `uint8_t`, `int8_t`, and `int16_t`.
+ */
+non_null() void *tox_memory_malloc(const Tox_Memory *mem, uint32_t size);
+
+/**
+ * @brief Allocate a vector (array) of zero-initialised objects.
+ *
+ * Always use as `(T *)tox_memory_calloc(mem, N, sizeof(T))`.
+ *
+ * @param mem The memory allocator.
+ * @param nmemb Number of array elements (can be 1 to allocate a single object).
+ * @param size Size in bytes of each element.
+ */
+non_null() void *tox_memory_calloc(const Tox_Memory *mem, uint32_t nmemb, uint32_t size);
+
+/**
+ * @brief Resize an object vector.
+ *
+ * Changes the size of (and possibly moves) the memory block pointed to by
+ * @p ptr to be large enough for an array of @p nmemb elements, each of which
+ * is @p size bytes. It is similar to the call
+ *
+ * @code
+ * realloc(ptr, nmemb * size);
+ * @endcode
+ *
+ * However, unlike that `realloc()` call, `mem_vrealloc()` fails safely in the
+ * case where the multiplication would overflow. If such an overflow occurs,
+ * `mem_vrealloc()` returns `nullptr`.
+ */
+non_null(1) nullable(2) void *tox_memory_vrealloc(const Tox_Memory *mem, void *ptr, uint32_t nmemb, uint32_t size);
+
+/** @brief Free an array, object, or object vector. */
+non_null(1) nullable(2) void tox_memory_dealloc(const Tox_Memory *mem, void *ptr);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif  // C_TOXCORE_TOXCORE_TOX_MEMORY_H
diff --git a/toxcore/tox_memory_impl.h b/toxcore/tox_memory_impl.h
new file mode 100644
index 00000000000..e369df115f8
--- /dev/null
+++ b/toxcore/tox_memory_impl.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2016-2018 The TokTok team.
+ * Copyright © 2013 Tox project.
+ */
+
+/**
+ * Datatypes, functions and includes for the core networking.
+ */
+#ifndef C_TOXCORE_TOXCORE_TOX_MEMORY_IMPL_H
+#define C_TOXCORE_TOXCORE_TOX_MEMORY_IMPL_H
+
+#include <stdint.h>     // uint*_t
+
+#include "tox_memory.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** @brief Allocate a byte array, similar to malloc. */
+typedef void *tox_memory_malloc_cb(void *self, uint32_t size);
+/** @brief Allocate a zero-initialised object array, similar to calloc. */
+typedef void *tox_memory_calloc_cb(void *self, uint32_t nmemb, uint32_t size);
+/** @brief Reallocate an object array, similar to realloc. */
+typedef void *tox_memory_vrealloc_cb(void *self, void *ptr, uint32_t nmemb, uint32_t size);
+/**
+ * @brief Deallocate a byte or object array, similar to free.
+ *
+ * Note that `tox_memory_free` will use this callback to deallocate itself, so
+ * once the deallocation is done, the allocator data structures can no longer be
+ * referenced.
+ */
+typedef void tox_memory_dealloc_cb(void *self, void *ptr);
+
+/** @brief Functions wrapping standard C memory allocation functions. */
+struct Tox_Memory_Funcs {
+    tox_memory_malloc_cb *malloc_callback;
+    tox_memory_calloc_cb *calloc_callback;
+    tox_memory_vrealloc_cb *realloc_callback;
+    tox_memory_dealloc_cb *dealloc_callback;
+};
+
+struct Tox_Memory {
+    const Tox_Memory_Funcs *funcs;
+    void *user_data;
+};
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif  // C_TOXCORE_TOXCORE_TOX_MEMORY_IMPL_H
diff --git a/toxcore/tox_network.c b/toxcore/tox_network.c
new file mode 100644
index 00000000000..f96a75f6c00
--- /dev/null
+++ b/toxcore/tox_network.c
@@ -0,0 +1,103 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+#include "tox_network.h"
+
+#include "ccompat.h"
+#include "tox_network_impl.h"
+
+Tox_Network *tox_network_new(const Tox_Network_Funcs *funcs, void *user_data, const Tox_Memory *mem)
+{
+    Tox_Network *ns = (Tox_Network *)tox_memory_calloc(mem, 1, sizeof(Tox_Network));
+
+    if (ns == nullptr) {
+        return nullptr;
+    }
+
+    ns->funcs = funcs;
+    ns->user_data = user_data;
+
+    ns->mem = mem;
+
+    return ns;
+}
+
+void tox_network_free(Tox_Network *ns)
+{
+    tox_memory_dealloc(ns->mem, ns);
+}
+
+int tox_network_close(const Tox_Network *ns, int sock)
+{
+    return ns->funcs->close_callback(ns->user_data, sock);
+}
+
+int tox_network_accept(const Tox_Network *ns, int sock)
+{
+    return ns->funcs->accept_callback(ns->user_data, sock);
+}
+
+int tox_network_bind(const Tox_Network *ns, int sock, const Network_Addr *addr)
+{
+    return ns->funcs->bind_callback(ns->user_data, sock, addr);
+}
+
+int tox_network_listen(const Tox_Network *ns, int sock, int backlog)
+{
+    return ns->funcs->listen_callback(ns->user_data, sock, backlog);
+}
+
+int tox_network_recvbuf(const Tox_Network *ns, int sock)
+{
+    return ns->funcs->recvbuf_callback(ns->user_data, sock);
+}
+
+int tox_network_recv(const Tox_Network *ns, int sock, uint8_t *buf, size_t len)
+{
+    return ns->funcs->recv_callback(ns->user_data, sock, buf, len);
+}
+
+int tox_network_recvfrom(const Tox_Network *ns, int sock, uint8_t *buf, size_t len, Network_Addr *addr)
+{
+    return ns->funcs->recvfrom_callback(ns->user_data, sock, buf, len, addr);
+}
+
+int tox_network_send(const Tox_Network *ns, int sock, const uint8_t *buf, size_t len)
+{
+    return ns->funcs->send_callback(ns->user_data, sock, buf, len);
+}
+
+int tox_network_sendto(const Tox_Network *ns, int sock, const uint8_t *buf, size_t len, const Network_Addr *addr)
+{
+    return ns->funcs->sendto_callback(ns->user_data, sock, buf, len, addr);
+}
+
+int tox_network_socket(const Tox_Network *ns, int domain, int type, int proto)
+{
+    return ns->funcs->socket_callback(ns->user_data, domain, type, proto);
+}
+
+int tox_network_socket_nonblock(const Tox_Network *ns, int sock, bool nonblock)
+{
+    return ns->funcs->socket_nonblock_callback(ns->user_data, sock, nonblock);
+}
+
+int tox_network_getsockopt(const Tox_Network *ns, int sock, int level, int optname, void *optval, size_t *optlen)
+{
+    return ns->funcs->getsockopt_callback(ns->user_data, sock, level, optname, optval, optlen);
+}
+
+int tox_network_setsockopt(const Tox_Network *ns, int sock, int level, int optname, const void *optval, size_t optlen)
+{
+    return ns->funcs->setsockopt_callback(ns->user_data, sock, level, optname, optval, optlen);
+}
+
+int tox_network_getaddrinfo(const Tox_Network *ns, int family, Network_Addr **addrs)
+{
+    return ns->funcs->getaddrinfo_callback(ns->user_data, family, addrs);
+}
+
+int tox_network_freeaddrinfo(const Tox_Network *ns, Network_Addr *addrs)
+{
+    return ns->funcs->freeaddrinfo_callback(ns->user_data, addrs);
+}
diff --git a/toxcore/tox_network.h b/toxcore/tox_network.h
new file mode 100644
index 00000000000..bb8f879ed2d
--- /dev/null
+++ b/toxcore/tox_network.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_TOX_NETWORK_H
+#define C_TOXCORE_TOXCORE_TOX_NETWORK_H
+
+#include <stdbool.h>
+#include <stddef.h>  // size_t
+
+#include "tox_memory.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct Tox_Network_Funcs Tox_Network_Funcs;
+
+typedef struct Tox_Network Tox_Network;
+
+non_null(1, 3) nullable(2)
+Tox_Network *tox_network_new(const Tox_Network_Funcs *funcs, void *user_data, const Tox_Memory *mem);
+
+nullable(1) void tox_network_free(Tox_Network *ns);
+
+/**
+ * @brief Wrapper for sockaddr_storage and size.
+ */
+typedef struct Network_Addr Network_Addr;
+
+non_null() int tox_network_close(const Tox_Network *ns, int sock);
+non_null() int tox_network_accept(const Tox_Network *ns, int sock);
+non_null() int tox_network_bind(const Tox_Network *ns, int sock, const Network_Addr *addr);
+non_null() int tox_network_listen(const Tox_Network *ns, int sock, int backlog);
+non_null() int tox_network_recvbuf(const Tox_Network *ns, int sock);
+non_null() int tox_network_recv(const Tox_Network *ns, int sock, uint8_t *buf, size_t len);
+non_null() int tox_network_recvfrom(const Tox_Network *ns, int sock, uint8_t *buf, size_t len, Network_Addr *addr);
+non_null() int tox_network_send(const Tox_Network *ns, int sock, const uint8_t *buf, size_t len);
+non_null() int tox_network_sendto(const Tox_Network *ns, int sock, const uint8_t *buf, size_t len, const Network_Addr *addr);
+non_null() int tox_network_socket(const Tox_Network *ns, int domain, int type, int proto);
+non_null() int tox_network_socket_nonblock(const Tox_Network *ns, int sock, bool nonblock);
+non_null() int tox_network_getsockopt(const Tox_Network *ns, int sock, int level, int optname, void *optval, size_t *optlen);
+non_null() int tox_network_setsockopt(const Tox_Network *ns, int sock, int level, int optname, const void *optval, size_t optlen);
+non_null() int tox_network_getaddrinfo(const Tox_Network *ns, int family, Network_Addr **addrs);
+non_null() int tox_network_freeaddrinfo(const Tox_Network *ns, Network_Addr *addrs);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_TOX_NETWORK_H
diff --git a/toxcore/tox_network_impl.h b/toxcore/tox_network_impl.h
new file mode 100644
index 00000000000..bc0217b7210
--- /dev/null
+++ b/toxcore/tox_network_impl.h
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_TOX_NETWORK_IMPL_H
+#define C_TOXCORE_TOXCORE_TOX_NETWORK_IMPL_H
+
+#include "tox_network.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef int tox_network_close_cb(void *self, int sock);
+typedef int tox_network_accept_cb(void *self, int sock);
+typedef int tox_network_bind_cb(void *self, int sock, const Network_Addr *addr);
+typedef int tox_network_listen_cb(void *self, int sock, int backlog);
+typedef int tox_network_recvbuf_cb(void *self, int sock);
+typedef int tox_network_recv_cb(void *self, int sock, uint8_t *buf, size_t len);
+typedef int tox_network_recvfrom_cb(void *self, int sock, uint8_t *buf, size_t len, Network_Addr *addr);
+typedef int tox_network_send_cb(void *self, int sock, const uint8_t *buf, size_t len);
+typedef int tox_network_sendto_cb(void *self, int sock, const uint8_t *buf, size_t len, const Network_Addr *addr);
+typedef int tox_network_socket_cb(void *self, int domain, int type, int proto);
+typedef int tox_network_socket_nonblock_cb(void *self, int sock, bool nonblock);
+typedef int tox_network_getsockopt_cb(void *self, int sock, int level, int optname, void *optval, size_t *optlen);
+typedef int tox_network_setsockopt_cb(void *self, int sock, int level, int optname, const void *optval, size_t optlen);
+typedef int tox_network_getaddrinfo_cb(void *self, int family, Network_Addr **addrs);
+typedef int tox_network_freeaddrinfo_cb(void *self, Network_Addr *addrs);
+
+/** @brief Functions wrapping POSIX network functions.
+ *
+ * Refer to POSIX man pages for documentation of what these functions are
+ * expected to do when providing alternative Network implementations.
+ */
+struct Tox_Network_Funcs {
+    tox_network_close_cb *close_callback;
+    tox_network_accept_cb *accept_callback;
+    tox_network_bind_cb *bind_callback;
+    tox_network_listen_cb *listen_callback;
+    tox_network_recvbuf_cb *recvbuf_callback;
+    tox_network_recv_cb *recv_callback;
+    tox_network_recvfrom_cb *recvfrom_callback;
+    tox_network_send_cb *send_callback;
+    tox_network_sendto_cb *sendto_callback;
+    tox_network_socket_cb *socket_callback;
+    tox_network_socket_nonblock_cb *socket_nonblock_callback;
+    tox_network_getsockopt_cb *getsockopt_callback;
+    tox_network_setsockopt_cb *setsockopt_callback;
+    tox_network_getaddrinfo_cb *getaddrinfo_callback;
+    tox_network_freeaddrinfo_cb *freeaddrinfo_callback;
+};
+
+struct Tox_Network {
+    const Tox_Network_Funcs *funcs;
+    void *user_data;
+
+    const Tox_Memory *mem;
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_TOX_NETWORK_IMPL_H
diff --git a/toxcore/tox_private.c b/toxcore/tox_private.c
index 72a93358a5b..cebdd502fd3 100644
--- a/toxcore/tox_private.c
+++ b/toxcore/tox_private.c
@@ -22,18 +22,6 @@
         }                             \
     } while (0)
 
-Tox_System tox_default_system(void)
-{
-    const Tox_System sys = {
-        nullptr,  // mono_time_callback
-        nullptr,  // mono_time_user_data
-        system_random(),
-        system_network(),
-        system_memory(),
-    };
-    return sys;
-}
-
 void tox_lock(const Tox *tox)
 {
     if (tox->mutex != nullptr) {
diff --git a/toxcore/tox_private.h b/toxcore/tox_private.h
index c82357170e6..ba6c8a27eb7 100644
--- a/toxcore/tox_private.h
+++ b/toxcore/tox_private.h
@@ -16,18 +16,6 @@
 extern "C" {
 #endif
 
-typedef uint64_t tox_mono_time_cb(void *user_data);
-
-struct Tox_System {
-    tox_mono_time_cb *mono_time_callback;
-    void *mono_time_user_data;
-    const struct Random *rng;
-    const struct Network *ns;
-    const struct Memory *mem;
-};
-
-Tox_System tox_default_system(void);
-
 void tox_lock(const Tox *tox);
 void tox_unlock(const Tox *tox);
 
diff --git a/toxcore/tox_random.c b/toxcore/tox_random.c
new file mode 100644
index 00000000000..ee014fdfd46
--- /dev/null
+++ b/toxcore/tox_random.c
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+#include "tox_random.h"
+
+#include "ccompat.h"
+#include "tox_random_impl.h"
+
+Tox_Random *tox_random_new(const Tox_Random_Funcs *funcs, void *user_data, const Tox_Memory *mem)
+{
+    Tox_Random *rng = (Tox_Random *)tox_memory_calloc(mem, 1, sizeof(Tox_Random));
+
+    if (rng == nullptr) {
+        return nullptr;
+    }
+
+    rng->funcs = funcs;
+    rng->user_data = user_data;
+
+    rng->mem = mem;
+
+    return rng;
+}
+
+void tox_random_free(Tox_Random *rng)
+{
+    tox_memory_dealloc(rng->mem, rng);
+}
+
+void tox_random_bytes(const Tox_Random *rng, uint8_t *bytes, uint32_t length)
+{
+    rng->funcs->bytes_callback(rng->user_data, bytes, length);
+}
+
+uint32_t tox_random_uniform(const Tox_Random *rng, uint32_t upper_bound)
+{
+    return rng->funcs->uniform_callback(rng->user_data, upper_bound);
+}
diff --git a/toxcore/tox_random.h b/toxcore/tox_random.h
new file mode 100644
index 00000000000..82e3acbcd71
--- /dev/null
+++ b/toxcore/tox_random.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_TOX_RANDOM_H
+#define C_TOXCORE_TOXCORE_TOX_RANDOM_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "tox_memory.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct Tox_Random_Funcs Tox_Random_Funcs;
+
+typedef struct Tox_Random Tox_Random;
+
+non_null(1, 3) nullable(2)
+Tox_Random *tox_random_new(const Tox_Random_Funcs *funcs, void *user_data, const Tox_Memory *mem);
+
+nullable(1) void tox_random_free(Tox_Random *rng);
+
+non_null() void tox_random_bytes(const Tox_Random *rng, uint8_t *bytes, uint32_t length);
+non_null() uint32_t tox_random_uniform(const Tox_Random *rng, uint32_t upper_bound);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_TOX_RANDOM_H
diff --git a/toxcore/tox_random_impl.h b/toxcore/tox_random_impl.h
new file mode 100644
index 00000000000..f11d2f26d6a
--- /dev/null
+++ b/toxcore/tox_random_impl.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_TOX_RANDOM_IMPL_H
+#define C_TOXCORE_TOXCORE_TOX_RANDOM_IMPL_H
+
+#include "tox_random.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef void tox_random_bytes_cb(void *self, uint8_t *bytes, uint32_t length);
+typedef uint32_t tox_random_uniform_cb(void *self, uint32_t upper_bound);
+
+struct Tox_Random_Funcs {
+    tox_random_bytes_cb *bytes_callback;
+    tox_random_uniform_cb *uniform_callback;
+};
+
+struct Tox_Random {
+    const Tox_Random_Funcs *funcs;
+    void *user_data;
+
+    const Tox_Memory *mem;
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_TOX_RANDOM_IMPL_H
diff --git a/toxcore/tox_struct.h b/toxcore/tox_struct.h
index b298269af95..ec1db247a7c 100644
--- a/toxcore/tox_struct.h
+++ b/toxcore/tox_struct.h
@@ -10,6 +10,7 @@
 #include "mem.h"
 #include "tox.h"
 #include "tox_private.h"
+#include "tox_system_impl.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/toxcore/tox_system.c b/toxcore/tox_system.c
new file mode 100644
index 00000000000..686b6f9484c
--- /dev/null
+++ b/toxcore/tox_system.c
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+#include "tox_system.h"
+
+#include "ccompat.h"
+#include "tox_system_impl.h"
+
+Tox_System *tox_system_new(const Tox_Logger *log, const Tox_Memory *mem, const Tox_Network *ns, const Tox_Random *rng, const Tox_Time *tm)
+{
+    Tox_System *sys = (Tox_System *)tox_memory_calloc(mem, 1, sizeof(Tox_System));
+
+    if (sys == nullptr) {
+        return nullptr;
+    }
+
+    sys->log = log;
+    sys->mem = mem;
+    sys->ns = ns;
+    sys->rng = rng;
+    sys->tm = tm;
+
+    return sys;
+}
+
+void tox_system_free(Tox_System *sys)
+{
+    tox_memory_dealloc(sys->mem, sys);
+}
diff --git a/toxcore/tox_system.h b/toxcore/tox_system.h
new file mode 100644
index 00000000000..49934017ff5
--- /dev/null
+++ b/toxcore/tox_system.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_TOX_SYSTEM_H
+#define C_TOXCORE_TOXCORE_TOX_SYSTEM_H
+
+#include "tox_logger.h"
+#include "tox_memory.h"
+#include "tox_network.h"
+#include "tox_random.h"
+#include "tox_time.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Operating system functions used by Tox.
+ *
+ * This struct is opaque and generally shouldn't be used in clients, but in
+ * combination with tox_private.h, it allows tests to inject non-IO (hermetic)
+ * versions of low level network, RNG, and time keeping functions.
+ */
+typedef struct Tox_System Tox_System;
+
+non_null() Tox_System *tox_system_new(const Tox_Logger *log, const Tox_Memory *mem, const Tox_Network *ns, const Tox_Random *rng, const Tox_Time *tm);
+nullable(1) void tox_system_free(Tox_System *sys);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_TOX_SYSTEM_H
diff --git a/toxcore/tox_system_impl.h b/toxcore/tox_system_impl.h
new file mode 100644
index 00000000000..bd74fd6e32a
--- /dev/null
+++ b/toxcore/tox_system_impl.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_TOX_SYSTEM_IMPL_H
+#define C_TOXCORE_TOXCORE_TOX_SYSTEM_IMPL_H
+
+#include "tox_system.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Tox_System {
+    const Tox_Logger *log;
+    const Tox_Memory *mem;
+    const Tox_Network *ns;
+    const Tox_Random *rng;
+    const Tox_Time *tm;
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_TOX_SYSTEM_IMPL_H
diff --git a/toxcore/tox_test.cc b/toxcore/tox_test.cc
index 530c1390a1f..2848a4fa2e6 100644
--- a/toxcore/tox_test.cc
+++ b/toxcore/tox_test.cc
@@ -6,6 +6,7 @@
 #include <vector>
 
 #include "crypto_core.h"
+#include "os_random.h"
 #include "tox_private.h"
 
 namespace {
@@ -94,7 +95,7 @@ TEST(Tox, OneTest)
 
     Tox *tox1 = tox_new(options, nullptr);
     ASSERT_NE(tox1, nullptr);
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
     set_random_name_and_status_message(tox1, rng, name.data(), status_message.data());
     Tox *tox2 = tox_new(options, nullptr);
diff --git a/toxcore/tox_time.c b/toxcore/tox_time.c
new file mode 100644
index 00000000000..637e17f8f00
--- /dev/null
+++ b/toxcore/tox_time.c
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+#include "tox_time.h"
+
+#include "ccompat.h"
+#include "tox_time_impl.h"
+
+Tox_Time *tox_time_new(const Tox_Time_Funcs *funcs, void *user_data, const Tox_Memory *mem)
+{
+    Tox_Time *tm = (Tox_Time *)tox_memory_calloc(mem, 1, sizeof(Tox_Time));
+
+    if (tm == nullptr) {
+        return nullptr;
+    }
+
+    tm->funcs = funcs;
+    tm->user_data = user_data;
+
+    tm->mem = mem;
+
+    return tm;
+}
+
+void tox_time_free(Tox_Time *tm)
+{
+    tox_memory_dealloc(tm->mem, tm);
+}
+
+uint64_t tox_time_monotonic(const Tox_Time *tm)
+{
+    return tm->funcs->monotonic_callback(tm->user_data);
+}
diff --git a/toxcore/tox_time.h b/toxcore/tox_time.h
new file mode 100644
index 00000000000..b8dd5c2cb6b
--- /dev/null
+++ b/toxcore/tox_time.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_TOX_TIME_H
+#define C_TOXCORE_TOXCORE_TOX_TIME_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "tox_memory.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct Tox_Time_Funcs Tox_Time_Funcs;
+
+typedef struct Tox_Time Tox_Time;
+
+non_null(1, 3) nullable(2)
+Tox_Time *tox_time_new(const Tox_Time_Funcs *funcs, void *user_data, const Tox_Memory *mem);
+
+nullable(1) void tox_time_free(Tox_Time *tm);
+
+non_null() uint64_t tox_time_monotonic(const Tox_Time *tm);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_TOX_TIME_H
diff --git a/toxcore/tox_time_impl.h b/toxcore/tox_time_impl.h
new file mode 100644
index 00000000000..300bc12b1f8
--- /dev/null
+++ b/toxcore/tox_time_impl.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later
+ * Copyright © 2022-2023 The TokTok team.
+ */
+
+#ifndef C_TOXCORE_TOXCORE_TOX_TIME_IMPL_H
+#define C_TOXCORE_TOXCORE_TOX_TIME_IMPL_H
+
+#include "tox_time.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef uint64_t tox_time_monotonic_cb(void *self);
+
+struct Tox_Time_Funcs {
+    tox_time_monotonic_cb *monotonic_callback;
+};
+
+struct Tox_Time {
+    const Tox_Time_Funcs *funcs;
+    void *user_data;
+
+    const Tox_Memory *mem;
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // C_TOXCORE_TOXCORE_TOX_TIME_IMPL_H
diff --git a/toxcore/tox_unpack.h b/toxcore/tox_unpack.h
index 5f0b18ad1b8..c07fe49445d 100644
--- a/toxcore/tox_unpack.h
+++ b/toxcore/tox_unpack.h
@@ -5,7 +5,7 @@
 #ifndef C_TOXCORE_TOXCORE_TOX_UNPACK_H
 #define C_TOXCORE_TOXCORE_TOX_UNPACK_H
 
-#include "attributes.h"
+#include "tox_attributes.h"
 #include "bin_unpack.h"
 #include "tox.h"
 
diff --git a/toxcore/util.h b/toxcore/util.h
index 44091b36227..e8067dbf77b 100644
--- a/toxcore/util.h
+++ b/toxcore/util.h
@@ -15,7 +15,7 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#include "attributes.h"
+#include "tox_attributes.h"
 #include "mem.h"
 
 #ifdef __cplusplus
diff --git a/toxcore/util_test.cc b/toxcore/util_test.cc
index 47bf258766b..3a31ce39363 100644
--- a/toxcore/util_test.cc
+++ b/toxcore/util_test.cc
@@ -3,12 +3,13 @@
 #include <gtest/gtest.h>
 
 #include "crypto_core.h"
+#include "os_random.h"
 
 namespace {
 
 TEST(Util, TwoRandomIdsAreNotEqual)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
     uint8_t pk1[CRYPTO_PUBLIC_KEY_SIZE];
     uint8_t sk1[CRYPTO_SECRET_KEY_SIZE];
@@ -23,7 +24,7 @@ TEST(Util, TwoRandomIdsAreNotEqual)
 
 TEST(Util, IdCopyMakesKeysEqual)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
     ASSERT_NE(rng, nullptr);
     uint8_t pk1[CRYPTO_PUBLIC_KEY_SIZE];
     uint8_t sk1[CRYPTO_SECRET_KEY_SIZE];
diff --git a/toxencryptsave.h b/toxencryptsave.h
new file mode 100644
index 00000000000..15e6502939d
--- /dev/null
+++ b/toxencryptsave.h
@@ -0,0 +1 @@
+#include "toxencryptsave/toxencryptsave.h"
diff --git a/toxencryptsave/BUILD.bazel b/toxencryptsave/BUILD.bazel
index bbd5e0ee88c..78312bd6cc3 100644
--- a/toxencryptsave/BUILD.bazel
+++ b/toxencryptsave/BUILD.bazel
@@ -22,6 +22,7 @@ cc_library(
         ":defines",
         "//c-toxcore/toxcore:ccompat",
         "//c-toxcore/toxcore:crypto_core",
+        "//c-toxcore/toxcore:os_random",
         "@libsodium",
     ],
 )
@@ -36,6 +37,7 @@ cc_library(
     deps = [
         "//c-toxcore/toxcore:ccompat",
         "//c-toxcore/toxcore:crypto_core",
+        "//c-toxcore/toxcore:os_random",
         "@libsodium",
     ],
 )
diff --git a/toxencryptsave/toxencryptsave.c b/toxencryptsave/toxencryptsave.c
index 45003055f42..343dde38cf6 100644
--- a/toxencryptsave/toxencryptsave.c
+++ b/toxencryptsave/toxencryptsave.c
@@ -15,6 +15,7 @@
 
 #include "../toxcore/ccompat.h"
 #include "../toxcore/crypto_core.h"
+#include "../toxcore/os_random.h"
 #include "defines.h"
 
 static_assert(TOX_PASS_SALT_LENGTH == crypto_pwhash_scryptsalsa208sha256_SALTBYTES,
@@ -115,7 +116,7 @@ bool tox_get_salt(const uint8_t *ciphertext, uint8_t *salt, Tox_Err_Get_Salt *er
 Tox_Pass_Key *tox_pass_key_derive(const uint8_t *passphrase, size_t passphrase_len,
                                   Tox_Err_Key_Derivation *error)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
 
     if (rng == nullptr) {
         SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_FAILED);
@@ -192,7 +193,7 @@ Tox_Pass_Key *tox_pass_key_derive_with_salt(const uint8_t *passphrase, size_t pa
 bool tox_pass_key_encrypt(const Tox_Pass_Key *key, const uint8_t *plaintext, size_t plaintext_len,
                           uint8_t *ciphertext, Tox_Err_Encryption *error)
 {
-    const Random *rng = system_random();
+    const Random *rng = os_random();
 
     if (rng == nullptr) {
         SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_FAILED);