From 2b611de45327678fb46f178159a8127cd2e0a1e2 Mon Sep 17 00:00:00 2001
From: Tristan Seifert <tristans@carbonrobotics.com>
Date: Thu, 5 Sep 2024 11:55:32 -0700
Subject: [PATCH] API to configure syslog server address at runtime

---
 include/zephyr/logging/log_backend.h |  3 ++
 subsys/logging/log_backend_net.c     | 45 +++++++++++++++++++++++-----
 2 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/include/zephyr/logging/log_backend.h b/include/zephyr/logging/log_backend.h
index 361d2cdceea9dd..4140bb49080c57 100644
--- a/include/zephyr/logging/log_backend.h
+++ b/include/zephyr/logging/log_backend.h
@@ -11,6 +11,7 @@
 #include <zephyr/sys/__assert.h>
 #include <zephyr/sys/util.h>
 #include <zephyr/logging/log_output.h>
+#include <zephyr/net/net_pkt.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -297,6 +298,8 @@ static inline int log_backend_format_set(const struct log_backend *backend, uint
 	return backend->api->format_set(backend, log_type);
 }
 
+int log_backend_net_set_server(struct sockaddr *newAddr);
+
 /**
  * @}
  */
diff --git a/subsys/logging/log_backend_net.c b/subsys/logging/log_backend_net.c
index 7b99a05856f296..59e8593f303f3f 100644
--- a/subsys/logging/log_backend_net.c
+++ b/subsys/logging/log_backend_net.c
@@ -36,6 +36,9 @@ struct sockaddr server_addr;
 static bool panic_mode;
 static uint32_t log_format_current = CONFIG_LOG_BACKEND_NET_OUTPUT_DEFAULT;
 
+// flag set when the log server has been overridden
+static bool gAddressOverride = false;
+
 const struct log_backend *log_backend_net_get(void);
 
 NET_PKT_SLAB_DEFINE(syslog_tx_pkts, CONFIG_LOG_BACKEND_NET_MAX_BUF);
@@ -201,14 +204,17 @@ static void init_net(struct log_backend const *const backend)
 	ARG_UNUSED(backend);
 	int ret;
 
-	net_sin(&server_addr)->sin_port = htons(514);
+	// only apply from config if never set
+	if(!gAddressOverride) {
+		net_sin(&server_addr)->sin_port = htons(514);
 
-	ret = net_ipaddr_parse(CONFIG_LOG_BACKEND_NET_SERVER,
-			       sizeof(CONFIG_LOG_BACKEND_NET_SERVER) - 1,
-			       &server_addr);
-	if (ret == 0) {
-		LOG_ERR("Cannot configure syslog server address");
-		return;
+		ret = net_ipaddr_parse(CONFIG_LOG_BACKEND_NET_SERVER,
+				sizeof(CONFIG_LOG_BACKEND_NET_SERVER) - 1,
+				&server_addr);
+		if (ret == 0) {
+			LOG_ERR("Cannot configure syslog server address");
+			return;
+		}
 	}
 
 	log_backend_deactivate(log_backend_net_get());
@@ -236,3 +242,28 @@ const struct log_backend *log_backend_net_get(void)
 {
 	return &log_backend_net;
 }
+
+/**
+ * @brief Set IP address of remote syslog server
+ *
+ * This must be called before the log backend is initialized.
+ *
+ * If not called, the default specified via config (CONFIG_LOG_BACKEND_NET_SERVER) is used.
+ */
+int log_backend_net_set_server(struct sockaddr *newAddr) {
+	if(!newAddr) {
+		return -EFAULT;
+	}
+
+	// musn't be initialized yet
+	if(net_init_done) {
+		// TODO: we could probably force re-initializing the socket
+		return -EINVAL;
+	}
+
+	// set it
+	server_addr = *newAddr;
+	gAddressOverride = true;
+
+	return 0;
+}