tg_cpphost: cmd_dynamic: Initial commit of cmd_InteractiveBash

src/cmd_dynamic/CMakeLists.txt

@@ -1,4 +1,7 @@
 set(DYNAMIC_CMDS_LIST DynTest)
+if (NOT WIN32)
+	set(DYNAMIC_CMDS_LIST InteractiveBash ${DYNAMIC_CMDS_LIST})
+endif()
 
 FILE(REMOVE ${CMAKE_SOURCE_DIR}/modules.load)
 foreach(lib ${DYNAMIC_CMDS_LIST})

src/cmd_dynamic/cmd_InteractiveBash.cpp

@@ -0,0 +1,236 @@
+#include <BotReplyMessage.h>
+#include <ExtArgs.h>
+#include <Logging.h>
+#include <fcntl.h>
+#include <stdio.h>
+
+#include <cstdlib>
+#include <regex>
+
+#include "NamespaceImport.h"
+#include "StringToolsExt.h"
+#include "cmd_dynamic.h"
+#include "popen_wdt/popen_wdt.h"
+
+#include <sys/mman.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "../ExtArgs.cpp"
+
+using pipe_t = int[2];
+
+// tochild { child stdin , parent write }
+// toparent { parent read, child stdout }
+static pipe_t tochild, toparent;
+static pid_t childpid = 0;
+static bool is_open = false;
+
+// Aliases
+static const int& child_stdin = tochild[0];
+static const int& child_stdout = toparent[1];
+static const int& parent_readfd = toparent[0];
+static const int& parent_writefd = tochild[1];
+
+static bool IsVaildPipe(pipe_t fd) {
+    return fd && (fd[0] >= 0 && fd[1] >= 0);
+}
+
+static void InvaildatePipe(pipe_t fd) {
+    if (fd) {
+        fd[0] = -1;
+        fd[1] = -1;
+    }
+}
+
+#define writeStr(fd, str) write(fd, str, sizeof(str))
+
+static bool SendCommand(const std::string& str) {
+    int rc;
+    std::string str_local = str;
+
+    TrimStr(str_local);
+    LOG_I("Command: %s", str_local.c_str());
+    // To stop the read() when the command exit
+    str_local += "; echo \" \"\n";
+    rc = write(parent_writefd, str_local.c_str(), str_local.size() + /* null terminator */ 1);
+    if (rc < 0) {
+        PLOG_E("Write command to parent fd");
+        return false;
+    }
+    return true;
+}
+
+// TODO This is broken (Will hang if its not interactive)
+static bool isChildInteractive() {
+    static const char OkStr[] = "OK\n ";
+    constexpr size_t OkStrLen = sizeof(OkStr);
+    char buf[OkStrLen] = {0};
+    int rc;
+
+    // Send a command to check connection to child bash process
+    rc = SendCommand("echo OK");
+    if (!rc) {
+        return false;
+    }
+    // Expecting "OK\n " (See above for extra space)
+    return read(parent_readfd, &buf, OkStrLen) == OkStrLen && !strncmp(buf, OkStr, OkStrLen - 1);
+}
+
+static void do_InteractiveBash(const Bot& bot, const Message::Ptr& message) {
+    static const std::regex kExitCommandRegex(R"(^exit( \d+)?$)");
+    std::string command;
+    bool matchesExit = false;
+
+    if (!hasExtArgs(message)) {
+        bot_sendReplyMessage(bot, message, "Send a bash command along /ibash");
+        return;
+    } else {
+        parseExtArgs(message, command);
+        matchesExit = std::regex_match(command, kExitCommandRegex);
+        if (matchesExit && !is_open) {
+            bot_sendReplyMessage(bot, message, "Bash subprocess is not open yet");
+            return;
+        }
+    }
+    if (!is_open) {
+        pid_t pid;
+        int rc;
+        pid_t* piddata = (pid_t*)mmap(NULL, sizeof(pid_t), PROT_READ | PROT_WRITE,
+                                      MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+        if (piddata == MAP_FAILED) {
+            perror("mmap");
+            return;
+        }
+
+        *piddata = 0;
+        InvaildatePipe(tochild);
+        InvaildatePipe(toparent);
+
+        // (-1 || -1) is 1, (-1 || 0) is 1, (0 || 0) is 0
+        rc = pipe(tochild) || pipe(toparent);
+
+        if (rc) {
+            perror("pipe");
+            return;
+        }
+        if ((pid = fork()) < 0) {
+            perror("fork");
+            return;
+        }
+        if (pid == 0) {
+            // Child
+            dup2(child_stdout, STDOUT_FILENO);
+            dup2(child_stdout, STDERR_FILENO);
+            dup2(child_stdin, STDIN_FILENO);
+            close(parent_readfd);
+            close(parent_writefd);
+            *piddata = getpid();
+            setpgid(0, 0);
+            execl("/bin/bash", "bash", (char*)NULL);
+            _exit(127);
+        } else {
+            close(child_stdin);
+            if (isChildInteractive()) {
+                is_open = true;
+                childpid = *piddata;
+                LOG_D("Open success, child pid: %d", childpid);
+                munmap(piddata, sizeof(pid_t));
+                bot_sendReplyMessage(bot, message, "Opened bash subprocess.");
+            } else {
+                LOG_W("Write failed, process not opened!");
+            }
+        }
+    }
+
+    if (IsVaildPipe(tochild) && IsVaildPipe(toparent)) {
+        // Is it exit command?
+        if (matchesExit) {
+            bool exited = false;
+            int status;
+
+            LOG_I("Received exit command: '%s'", command.c_str());
+            // TODO Need to send SIGINT to child of childpid not itself
+            // However if kill SIGINT is not here, it wouldnt exit if command is hanging
+            kill(childpid, SIGINT);
+            SendCommand("exit 0");
+            wait(&status);
+            exited = WIFEXITED(status);
+            if (!exited && kill(childpid, 0) == 0) {
+                LOG_W("Process %d misbehaving, using SIGTERM", childpid);
+                killpg(childpid, SIGTERM);
+            }
+            bot_sendReplyMessage(bot, message, "Closed bash subprocess.");
+            close(parent_readfd);
+            close(parent_writefd);
+            close(child_stdout);
+            childpid = -1;
+            is_open = false;
+        } else {
+            // Second try, it should have been opened by now or else its a failure
+            if (is_open) {
+                static const char kExitedByTimeout[] = WDT_BITE_STR;
+                char buf[512];
+                int rc;
+                std::string result;
+                auto sendFallback = std::make_shared<bool>(true);
+
+                // TODO These results will come in next
+                SendCommand(command);
+
+                // Write a msg as a fallback if read() hangs
+                std::thread th([sendFallback] {
+                    std_sleep(std::chrono::seconds(SLEEP_SECONDS));
+                    if (*sendFallback)
+                        writeStr(child_stdout, kExitedByTimeout);
+                });
+                // When rc < 0, most likely it returned EWOUDLBLOCK/EAGAIN
+                do {
+                    memset(buf, 0, sizeof(buf));
+                    rc = read(parent_readfd, buf, sizeof(buf));
+                    if (rc > 0) {
+                        // Cuz of the shim of " \n", since it is a sperate process, may not be read
+                        // in the same buffer.
+                        // TODO: Make it in a common way somehow
+                        if (!strncmp(buf, " \n", sizeof(buf))) {
+                            // TODO This is a hack
+                            rc = sizeof(buf);
+                        } else {
+                            result.append(buf, rc);
+                        }
+                    }
+                    // Exit if read ret != buf size
+                } while (rc > 0 && rc == sizeof(buf));
+
+                // Was it the fallback input?
+                if (strncmp(buf, kExitedByTimeout, sizeof(buf))) {
+                    // No? then set to not write fallback and detach
+                    *sendFallback = false;
+                    th.detach();
+                } else {
+                    // Yes? Do join then
+                    if (th.joinable())
+                        th.join();
+                }
+
+                if (isEmptyOrBlank(result))
+                    result = "(No output)";
+                bot_sendReplyMessage(bot, message, result);
+            } else {
+                bot_sendReplyMessage(bot, message, "Failed to open child process");
+            }
+        }
+    } else {
+        LOG_E("Pipes are not vaild, this is a BUG");
+    }
+}
+
+static bool isSupported(void) {
+#ifdef __WIN32
+    return false;
+#else
+    return access("/bin/bash", R_OK | X_OK) == 0;
+#endif
+}
+
+DECL_DYN_ENFORCED_COMMAND("ibash", do_InteractiveBash, isSupported);