Use fork for connection handlers (preferrably), fix memory leak

[guacd.git] / src / daemon.c

diff --git a/src/daemon.c b/src/daemon.c
index 3029fc5..839d30f 100644 (file)
--- a/src/daemon.c
+++ b/src/daemon.c
@@ -39,6 +39,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <signal.h>
 #include <sys/types.h>
 
 #ifdef __MINGW32__
@@ -79,7 +80,6 @@ char* lasterror() {
 #endif
 }
 
-
 typedef struct client_thread_data {
 
     int fd;
@@ -92,28 +92,28 @@ void* start_client_thread(void* data) {
     guac_client* client;
     client_thread_data* thread_data = (client_thread_data*) data;
 
-    GUAC_LOG_INFO("Spawning client");
+    guac_log_info("Spawning client");
 
     /* Load and start client */
     client = guac_get_client(thread_data->fd); 
 
     if (client == NULL) {
-        GUAC_LOG_ERROR("Client retrieval failed");
+        guac_log_error("Client retrieval failed");
+        free(data);
         return NULL;
     }
 
     guac_start_client(client);
-
     guac_free_client(client);
 
     /* Close socket */
     if (CLOSE_SOCKET(thread_data->fd) < 0) {
-        GUAC_LOG_ERROR("Error closing connection: %s", lasterror());
+        guac_log_error("Error closing connection: %s", lasterror());
         free(data);
         return NULL;
     }
 
-    GUAC_LOG_INFO("Client finished");
+    guac_log_info("Client finished");
     free(data);
     return NULL;
 
@@ -228,24 +228,37 @@ int main(int argc, char* argv[]) {
         exit(EXIT_SUCCESS);
     }
 #else
-    GUAC_LOG_INFO("fork() not defined at compile time.");
-    GUAC_LOG_INFO("guacd running in foreground only.");
+    daemon_pid = getpid();
+    guac_log_info("fork() not defined at compile time.");
+    guac_log_info("guacd running in foreground only.");
 #endif
 
     /* Otherwise, this is the daemon */
-    GUAC_LOG_INFO("Started, listening on port %i", listen_port);
+    guac_log_info("Started, listening on port %i", listen_port);
+
+    /* Ignore SIGPIPE */
+    if (signal(SIGPIPE, SIG_IGN) == SIG_ERR) {
+        guac_log_error("Could not set handler for SIGPIPE to ignore. SIGPIPE may cause termination of the daemon.");
+    }
+
+    /* Ignore SIGCHLD (force automatic removal of children) */
+    if (signal(SIGCHLD, SIG_IGN) == SIG_ERR) {
+        guac_log_error("Could not set handler for SIGCHLD to ignore. Child processes may pile up in the process table.");
+    }
 
     /* Daemon loop */
     for (;;) {
 
-#ifdef HAVE_LIBPTHREAD
+#ifdef HAVE_FORK
+        pid_t child_pid;
+#elif HAVE_LIBPTHREAD
         pthread_t thread;
 #endif
         client_thread_data* data;
 
         /* Listen for connections */
         if (listen(socket_fd, 5) < 0) {
-            GUAC_LOG_ERROR("Could not listen on socket: %s", lasterror());
+            guac_log_error("Could not listen on socket: %s", lasterror());
             return 3;
         }
 
@@ -253,35 +266,75 @@ int main(int argc, char* argv[]) {
         client_addr_len = sizeof(client_addr);
         connected_socket_fd = accept(socket_fd, (struct sockaddr*) &client_addr, &client_addr_len);
         if (connected_socket_fd < 0) {
-            GUAC_LOG_ERROR("Could not accept client connection: %s", lasterror());
+            guac_log_error("Could not accept client connection: %s", lasterror());
             return 3;
         }
 
         data = malloc(sizeof(client_thread_data));
         data->fd = connected_socket_fd;
 
-#ifdef HAVE_LIBPTHREAD
-        if (pthread_create(&thread, NULL, start_client_thread, (void*) data)) {
-            GUAC_LOG_ERROR("Could not create client thread: %s", lasterror());
-            return 3;
+        /* 
+         * Once connection is accepted, send child into background, whether through
+         * fork() or through creating a thread. If thead support is not present on
+         * the platform, guacd will still work, but will only be able to handle one
+         * connection at a time.
+         */
+
+#ifdef HAVE_FORK
+
+        /*** FORK ***/
+
+        /*
+         * Note that we prefer fork() over pthreads for connection-handling
+         * processes as they give each connection its own memory area, and
+         * isolate the main daemon and other connections from errors in any
+         * particular client plugin.
+         */
+
+        child_pid = fork();
+
+        /* If error, log */
+        if (child_pid == -1)
+            guac_log_error("Error forking child process: %s\n", lasterror());
+
+        /* If child, start client, and exit when finished */
+        else if (child_pid == 0) {
+            start_client_thread(data);
+            return 0;
         }
+
+#elif HAVE_LIBPTHREAD
+
+        /*** PTHREADS ***/
+
+        if (pthread_create(&thread, NULL, start_client_thread, (void*) data))
+            guac_log_error("Could not create client thread: %s", lasterror());
+        else
+            pthread_detach(thread);
+
 #elif __MINGW32__
-        if (_beginthread(start_client_thread, 0, (void*) data) == -1L) { 
-            GUAC_LOG_ERROR("Could not create client thread: %s", lasterror());
-            return 3;
-        }
+
+        /*** Windows threads ***/
+
+        if (_beginthread(start_client_thread, 0, (void*) data) == -1L) 
+            guac_log_error("Could not create client thread: %s", lasterror());
+
 #else
 #warning THREAD SUPPORT NOT FOUND! guacd will only be able to handle one connection at a time.
-        GUAC_LOG_INFO("Thread support not present at compile time.");
-        GUAC_LOG_INFO("guacd handling one connection at a time.");
+
+        /*** NO THREADS ***/
+
+        guac_log_info("Thread support not present at compile time.");
+        guac_log_info("guacd handling one connection at a time.");
         start_client_thread(data);
+
 #endif
 
     }
 
     /* Close socket */
     if (CLOSE_SOCKET(socket_fd) < 0) {
-        GUAC_LOG_ERROR("Could not close socket: %s", lasterror());
+        guac_log_error("Could not close socket: %s", lasterror());
         return 3;
     }