Support for "ready" message (both client and server)

libguac/include/protocol.h

@@ -123,6 +123,20 @@ void guac_send_name(GUACIO* io, const char* name);
  */
 void guac_send_error(GUACIO* io, const char* error);
 
+/**
+ * Sends a ready instruction over the given GUACIO connection. The
+ * ready instruction merely signals the client that its ready
+ * instruction has been handled. The ready exchange is intended to
+ * synchronize instruction handling (if needed) and serve as a health
+ * indicator for both client and server.
+ *
+ * Normally, this functino should not be called by client plugins, as
+ * the ready instruction will be handled automatically.
+ *
+ * @param io The GUACIO connection to use.
+ */
+void guac_send_ready(GUACIO* io);
+
 /**
  * Sends a clipboard instruction over the given GUACIO connection. The
  * clipboard data given will be automatically escaped for transmission.

libguac/src/client.c

@@ -236,18 +236,6 @@ void guac_start_client(guac_client* client) {
     /* VNC Client Loop */
     for (;;) {
 
-        /* Handle server messages */
-        if (client->handle_messages) {
-
-            int retval = client->handle_messages(client);
-            if (retval) {
-                syslog(LOG_ERR, "Error handling server messages");
-                return;
-            }
-
-            guac_flush(io);
-        }
-
         wait_result = guac_instructions_waiting(io);
         if (wait_result > 0) {
 
@@ -258,7 +246,25 @@ void guac_start_client(guac_client* client) {
            
                 do {
 
-                    if (strcmp(instruction.opcode, "mouse") == 0) {
+                    if (strcmp(instruction.opcode, "ready") == 0) {
+
+                        /* Handle server messages */
+                        if (client->handle_messages) {
+
+                            int retval = client->handle_messages(client);
+                            if (retval) {
+                                syslog(LOG_ERR, "Error handling server messages");
+                                return;
+                            }
+
+                        }
+
+                        guac_send_ready(io);
+                        guac_flush(io);
+
+                    }
+
+                    else if (strcmp(instruction.opcode, "mouse") == 0) {
                         if (client->mouse_handler)
                             if (
                                     client->mouse_handler(

libguac/src/protocol.c

@@ -175,6 +175,10 @@ void guac_send_size(GUACIO* io, int w, int h) {
     guac_write_string(io, ";");
 }
 
+void guac_send_ready(GUACIO* io) {
+    guac_write_string(io, "ready;");
+}
+
 void guac_send_clipboard(GUACIO* io, const char* data) {
 
     char* escaped = guac_escape_string(data);