Add file instruction handler and event, modify parser to not drop length if only partially received.

guacamole-common-js/src/main/resources/guacamole.js

@@ -82,7 +82,7 @@ Guacamole.Parser = function() {
     this.receive = function(packet) {
 
         // Truncate buffer as necessary
-        if (start_index > 4096) {
+        if (start_index > 4096 && element_end >= start_index) {
 
             buffer = buffer.substring(start_index);
 
@@ -473,6 +473,18 @@ Guacamole.Client = function(tunnel) {
      */
     this.onresize = null;
 
+    /**
+     * Fired when a file is received. Note that this will contain the entire
+     * data of the file.
+     * 
+     * @event
+     * @param {String} name A human-readable name describing the file.
+     * @param {String} mimetype The mimetype of the file received.
+     * @param {String} data The actual entire contents of the file,
+     *                      base64-encoded.
+     */
+    this.onfile = null;
+
     // Layers
     function getBufferLayer(index) {
 
@@ -773,6 +785,15 @@ Guacamole.Client = function(tunnel) {
             guac_client.disconnect();
         },
 
+        "file": function(parameters) {
+            if (guac_client.onfile)
+                guac_client.onfile(
+                    parameters[0], // Name
+                    parameters[1], // Mimetype
+                    parameters[2]  // Data
+                );
+        },
+
         "identity": function(parameters) {
 
             var layer = getLayer(parseInt(parameters[0]));