GUACAMOLE-629: Add support for updating connection parameters of in-progress connections.

src/libguac/guacamole/user-fntypes.h

@@ -237,6 +237,36 @@ typedef int guac_user_file_handler(guac_user* user, guac_stream* stream,
 typedef int guac_user_pipe_handler(guac_user* user, guac_stream* stream,
         char* mimetype, char* name);
 
+/**
+ * Handler for Guacamole argument value (argv) streams received from a user.
+ * Argument value streams are real-time revisions to the connection parameters
+ * of an in-progress connection. Each such argument value stream begins when
+ * the user sends a "argv" instruction. To handle received data along this
+ * stream, implementations of this handler must assign blob and end handlers to
+ * the given stream object.
+ *
+ * @param user
+ *     The user that opened the argument value stream.
+ *
+ * @param stream
+ *     The stream object allocated by libguac to represent the argument value
+ *     stream opened by the user.
+ *
+ * @param mimetype
+ *     The mimetype of the data that will be sent along the stream.
+ *
+ * @param name
+ *     The name of the connection parameter being updated. It is up to the
+ *     implementation of this handler to decide whether and how to update a
+ *     connection parameter.
+ *
+ * @return
+ *     Zero if the opening of the argument value stream has been handled
+ *     successfully, or non-zero if an error occurs.
+ */
+typedef int guac_user_argv_handler(guac_user* user, guac_stream* stream,
+        char* mimetype, char* name);
+
 /**
  * Handler for Guacamole stream blobs. Each blob originates from a "blob"
  * instruction which was associated with a previously-created stream.

src/libguac/guacamole/user.h

@@ -475,6 +475,27 @@ struct guac_user {
      */
     guac_user_audio_handler* audio_handler;
 
+    /**
+     * Handler for argv events (updates to the connection parameters of an
+     * in-progress connection) sent by the Guacamole web-client.
+     *
+     * The handler takes a guac_stream which contains the stream index and
+     * will persist through the duration of the transfer, the mimetype of
+     * the data being transferred, and the argument (connection parameter)
+     * name.
+     *
+     * Example:
+     * @code
+     *     int argv_handler(guac_user* user, guac_stream* stream,
+     *             char* mimetype, char* name);
+     *
+     *     int guac_user_init(guac_user* user, int argc, char** argv) {
+     *         user->argv_handler = argv_handler;
+     *     }
+     * @endcode
+     */
+    guac_user_argv_handler* argv_handler;
+
 };
 
 /**

src/libguac/user-handlers.c

@@ -49,6 +49,7 @@ __guac_instruction_handler_mapping __guac_instruction_handler_map[] = {
    {"get",        __guac_handle_get},
    {"put",        __guac_handle_put},
    {"audio",      __guac_handle_audio},
+   {"argv",       __guac_handle_argv},
    {NULL,         NULL}
 };
 
@@ -382,6 +383,30 @@ int __guac_handle_pipe(guac_user* user, int argc, char** argv) {
     return 0;
 }
 
+int __guac_handle_argv(guac_user* user, int argc, char** argv) {
+
+    /* Pull corresponding stream */
+    int stream_index = atoi(argv[0]);
+    guac_stream* stream = __init_input_stream(user, stream_index);
+    if (stream == NULL)
+        return 0;
+
+    /* If supported, call handler */
+    if (user->argv_handler)
+        return user->argv_handler(
+            user,
+            stream,
+            argv[1], /* mimetype */
+            argv[2]  /* name */
+        );
+
+    /* Otherwise, abort */
+    guac_protocol_send_ack(user->socket, stream,
+            "Reconfiguring in-progress connections unsupported",
+            GUAC_PROTOCOL_STATUS_UNSUPPORTED);
+    return 0;
+}
+
 int __guac_handle_ack(guac_user* user, int argc, char** argv) {
 
     guac_stream* stream;

src/libguac/user-handlers.h

@@ -120,6 +120,13 @@ __guac_instruction_handler __guac_handle_file;
  */
 __guac_instruction_handler __guac_handle_pipe;
 
+/**
+ * Internal initial handler for the argv instruction. When a argv instruction
+ * is received, this handler will be called. The client's argv handler will
+ * be invoked if defined.
+ */
+__guac_instruction_handler __guac_handle_argv;
+
 /**
  * Internal initial handler for the ack instruction. When a ack instruction
  * is received, this handler will be called. The client's ack handler will