Add nest instruction.

libguac/include/protocol.h

@@ -215,6 +215,22 @@ int guac_protocol_send_disconnect(guac_socket* socket);
  */
 int guac_protocol_send_error(guac_socket* socket, const char* error);
 
+/**
+ * Sends a nest instruction over the given guac_socket connection.
+ *
+ * If an error occurs sending the instruction, a non-zero value is
+ * returned, and guac_error is set appropriately.
+ *
+ * @param socket The guac_socket connection to use.
+ * @param index The integer index of the stram to send the protocol
+ *              data over.
+ * @param data A string containing protocol data, which must be UTF-8
+ *             encoded and null-terminated.
+ * @return Zero on success, non-zero on error.
+ */
+int guac_protocol_send_nest(guac_socket* socket, int index,
+        const char* data);
+
 /**
  * Sends a set instruction over the given guac_socket connection.
  *

libguac/src/protocol.c

@@ -715,6 +715,17 @@ int guac_protocol_send_name(guac_socket* socket, const char* name) {
 
 }
 
+int guac_protocol_send_nest(guac_socket* socket, int index,
+        const char* data) {
+
+    return
+           guac_socket_write_string(socket, "4.nest,")
+        || __guac_socket_write_length_int(socket, index)
+        || guac_socket_write_string(socket, ",")
+        || __guac_socket_write_length_string(socket, data)
+        || guac_socket_write_string(socket, ";");
+
+}
 
 int guac_protocol_send_png(guac_socket* socket, guac_composite_mode mode,
         const guac_layer* layer, int x, int y, cairo_surface_t* surface) {