GUACAMOLE-600: Add support for setting the Telnet connection timeout.

src/protocols/telnet/settings.c

@@ -37,6 +37,7 @@
 const char* GUAC_TELNET_CLIENT_ARGS[] = {
     "hostname",
     "port",
+    "timeout",
     "username",
     "username-regex",
     "password",
@@ -81,6 +82,11 @@ enum TELNET_ARGS_IDX {
      */
     IDX_PORT,
 
+    /**
+     * The number of seconds to wait for the remote server to respond. Optional.
+     */
+    IDX_TIMEOUT,
+
     /**
      * The name of the user to login as. Optional.
      */
@@ -429,6 +435,11 @@ guac_telnet_settings* guac_telnet_parse_args(guac_user* user,
         guac_user_parse_args_string(user, GUAC_TELNET_CLIENT_ARGS, argv,
                 IDX_PORT, GUAC_TELNET_DEFAULT_PORT);
 
+    /* Read connection timeout */
+    settings->timeout =
+        guac_user_parse_args_int(user, GUAC_TELNET_CLIENT_ARGS, argv,
+                IDX_TIMEOUT, GUAC_TELNET_DEFAULT_TIMEOUT);
+
     /* Read typescript path */
     settings->typescript_path =
         guac_user_parse_args_string(user, GUAC_TELNET_CLIENT_ARGS, argv,

src/protocols/telnet/settings.h

@@ -33,6 +33,12 @@
  */
 #define GUAC_TELNET_DEFAULT_PORT "23"
 
+/**
+ * The default number of seconds to wait for a successful connection before
+ * timing out.
+ */
+#define GUAC_TELNET_DEFAULT_TIMEOUT 10
+
 /**
  * The filename to use for the typescript, if not specified.
  */
@@ -72,6 +78,11 @@ typedef struct guac_telnet_settings {
      */
     char* port;
 
+    /**
+     * The number of seconds to wait for a connection before timing out.
+     */
+    int timeout;
+
     /**
      * The name of the user to login as, if any. If no username is specified,
      * this will be NULL.

src/protocols/telnet/telnet.c

@@ -424,9 +424,25 @@ static telnet_t* __guac_telnet_create_session(guac_client* client) {
                 NI_NUMERICHOST | NI_NUMERICSERV)))
             guac_client_log(client, GUAC_LOG_DEBUG, "Unable to resolve host: %s", gai_strerror(retval));
 
-        /* Connect */
+        fd_set fdset;
-        if (connect(fd, current_address->ai_addr,
+        FD_ZERO(&fdset);
-                        current_address->ai_addrlen) == 0) {
+        FD_SET(fd, &fdset);
+
+        struct timeval timeout_tv;
+        timeout_tv.tv_sec = settings->timeout;
+        timeout_tv.tv_usec = 0;
+
+        connect(fd, current_address->ai_addr, current_address->ai_addrlen);
+        
+        retval = select(fd + 1, NULL, &fdset, NULL, &timeout_tv);
+
+        if (retval == 0) {
+            guac_client_log(client, GUAC_LOG_ERROR, "Timeout connecting to "
+                    "host %s, port %s", connected_address, connected_port);
+            continue;
+        }
+
+        else if (retval > 0) {
 
             guac_client_log(client, GUAC_LOG_DEBUG, "Successfully connected to "
                     "host %s, port %s", connected_address, connected_port);