messages: Rework ssh_message_queue()

Return early and make it easier to understand.

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>

src/messages.c

@@ -411,9 +411,15 @@ static int ssh_execute_message_callback(ssh_session session, ssh_message msg) {
  */
 static void ssh_message_queue(ssh_session session, ssh_message message)
 {
-    if (message != NULL) {
 #ifdef WITH_SERVER
     int ret;
+#endif
+
+    if (message == NULL) {
+        return;
+    }
+
+#ifdef WITH_SERVER
     /* probably not the best place to execute server callbacks, but still better
      * than nothing.
      */
@@ -423,10 +429,13 @@ static void ssh_message_queue(ssh_session session, ssh_message message)
         return;
     }
 #endif /* WITH_SERVER */
+
     if (session->ssh_message_callback != NULL) {
+        /* This will transfer the message, do not free. */
         ssh_execute_message_callback(session, message);
         return;
     }
+
     if (session->server_callbacks != NULL) {
         /* if we have server callbacks, but nothing was executed, it means we are
          * in non-synchronous mode, and we just don't care about the message we
@@ -436,20 +445,24 @@ static void ssh_message_queue(ssh_session session, ssh_message message)
         ssh_message_free(message);
         return;
     }
+
     if (session->ssh_message_list == NULL) {
         session->ssh_message_list = ssh_list_new();
-        }
         if (session->ssh_message_list != NULL) {
-            ssh_list_append(session->ssh_message_list, message);
+            /*
-        } else {
+             * If the message list couldn't be allocated, the message can't be
-            /* If the message list couldn't be allocated, the message can't be
+             * enqueued
-             * enqueued */
+             */
             ssh_message_reply_default(message);
             ssh_set_error_oom(session);
             ssh_message_free(message);
             return;
         }
     }
+
+    /* This will transfer the message, do not free. */
+    ssh_list_append(session->ssh_message_list, message);
+    return;
 }
 
 /**