websock.js: simpler binary support, protocols param.

Use a simpler method of enabling binary transfer over WebSockets. This
still presents the user of websock.js with a plain javascript array
for the receive queue data. However, if binary support is supported
and requested then the transfer will be raw frames instead of base64
encoded.

Lots of room for optimization here but for now correct is better than
fast.

Pull from websockify 17175afd7311c55abd8d

include/rfb.js

@@ -299,7 +299,8 @@ function connect() {
         uri += rfb_host + ":" + rfb_port + "/" + rfb_path;
     }
     Util.Info("connecting to " + uri);
-    ws.open(uri);
+    // TODO: make protocols a configurable
+    ws.open(uri, ['binary', 'base64']);
 
     Util.Debug("<< RFB.connect");
 }
@@ -1252,11 +1253,11 @@ encHandlers.HEXTILE = function display_hextile() {
             rQi += FBU.bytes - 1;
         } else {
             if (FBU.subencoding & 0x02) { // Background
-                FBU.background = rQ.subarray(rQi, rQi + fb_Bpp);
+                FBU.background = rQ.slice(rQi, rQi + fb_Bpp);
                 rQi += fb_Bpp;
             }
             if (FBU.subencoding & 0x04) { // Foreground
-                FBU.foreground = rQ.subarray(rQi, rQi + fb_Bpp);
+                FBU.foreground = rQ.slice(rQi, rQi + fb_Bpp);
                 rQi += fb_Bpp;
             }
 
@@ -1266,7 +1267,7 @@ encHandlers.HEXTILE = function display_hextile() {
                 rQi += 1;
                 for (s = 0; s < subrects; s += 1) {
                     if (FBU.subencoding & 0x10) { // SubrectsColoured
-                        color = rQ.subarray(rQi, rQi + fb_Bpp);
+                        color = rQ.slice(rQi, rQi + fb_Bpp);
                         rQi += fb_Bpp;
                     } else {
                         color = FBU.foreground;

include/util.js

@@ -18,10 +18,6 @@ var Util = {};
  * Make arrays quack
  */
 
-Array.prototype.subarray = function (start, end) {
-    this.slice(start, end);
-};
-
 Array.prototype.push8 = function (num) {
     this.push(num & 0xFF);
 };

include/websock.js

@@ -61,7 +61,6 @@ function Websock() {
 
 var api = {},         // Public API
     websocket = null, // WebSocket object
-    protocols,        // Protocols to request in priority order
     mode = 'base64',
     rQ = [],          // Receive queue
     rQi = 0,          // Receive queue index
@@ -125,46 +124,24 @@ function rQshift32() {
            (rQ[rQi++] <<  8) +
            (rQ[rQi++]      );
 }
-function rQslice(start, end) {
-    if (mode === 'binary') {
-        if (end) {
-            return rQ.subarray(rQi + start, rQi + end);
-        } else {
-            return rQ.subarray(rQi + start);
-        }
-    } else {
-        if (end) {
-            return rQ.slice(rQi + start, rQi + end);
-        } else {
-            return rQ.slice(rQi + start);
-        }
-    }
-}
-
 function rQshiftStr(len) {
     if (typeof(len) === 'undefined') { len = rQlen(); }
-    var arr = rQslice(0, len);
+    var arr = rQ.slice(rQi, rQi + len);
     rQi += len;
     return String.fromCharCode.apply(null, arr);
 }
 function rQshiftBytes(len) {
     if (typeof(len) === 'undefined') { len = rQlen(); }
-    var a = rQslice(0, len), b = [];
-    if (mode === 'binary') {
-        // Convert to plain array
-        b.push.apply(b, a);
-    } else {
-        // Already plain array, just return the original
-        b = a
-    }
     rQi += len;
-    return b;
+    return rQ.slice(rQi-len, rQi);
 }
-function rQshiftArray(len) {
-    if (typeof(len) === 'undefined') { len = rQlen(); }
-    var a = rQslice(0, len);
-    rQi += len;
-    return a;
+
+function rQslice(start, end) {
+    if (end) {
+        return rQ.slice(rQi + start, rQi + end);
+    } else {
+        return rQ.slice(rQi + start);
+    }
 }
 
 // Check to see if we must wait for 'num' bytes (default to FBU.bytes)
@@ -202,14 +179,10 @@ function encode_message() {
 function decode_message(data) {
     //Util.Debug(">> decode_message: " + data);
     if (mode === 'binary') {
-        // Create new arraybuffer and dump old and new data into it 
-        // TODO: this could be far more efficient and re-use the array
-        var new_rQ = new Uint8Array(rQ.length + data.byteLength);
-        new_rQ.set(rQ);
-        new_rQ.set(new Uint8Array(data), rQ.length);
-        rQ = new_rQ;
+        // push arraybuffer values onto the end
+        rQ.push.apply(rQ, (new Uint8Array(data)));
     } else {
-        /* base64 decode and concat to the end */
+        // base64 decode and concat to the end
         rQ = rQ.concat(Base64.decode(data, 0));
     }
     //Util.Debug(">> decode_message, rQ: " + rQ);
@@ -265,7 +238,7 @@ function recv_message(e) {
             // Compact the receive queue
             if (rQ.length > rQmax) {
                 //Util.Debug("Compacting receive queue");
-                rQ = rQslice(rQi);
+                rQ = rQ.slice(rQi);
                 rQi = 0;
             }
         } else {
@@ -294,40 +267,62 @@ function on(evt, handler) {
     eventHandlers[evt] = handler;
 }
 
-function init() {
+function init(protocols) {
     rQ         = [];
     rQi        = 0;
     sQ         = [];
-    websocket  = null,
-    protocols  = "base64";
+    websocket  = null;
 
     var bt = false,
-        wsbt = false;
+        wsbt = false,
+        try_binary = false;
 
+    // Check for full typed array support
     if (('Uint8Array' in window) &&
         ('set' in Uint8Array.prototype)) {
         bt = true;
     }
+
+    // Check for full binary type support in WebSockets
     // TODO: this sucks, the property should exist on the prototype
     // but it does not.
     try {
         if (bt && ('binaryType' in (new WebSocket("ws://localhost:17523")))) {
+            Util.Info("Detected binaryType support in WebSockets");
             wsbt = true;
         }
     } catch (exc) {
         // Just ignore failed test localhost connections
     }
-    if (bt && wsbt) {
-        Util.Info("Detected binaryType support in WebSockets");
-        protocols = ['binary', 'base64'];
-    } else {
-        Util.Info("No binaryType support in WebSockets, using base64 encoding");
-        protocols = 'base64';
+
+    // Default protocols if not specified
+    if (typeof(protocols) === "undefined") {
+        if (wsbt) {
+            protocols = ['binary', 'base64'];
+        } else {
+            protocols = 'base64';
+        }
     }
+
+    // If no binary support, make sure it was not requested
+    if (!wsbt) {
+        if (protocols === 'binary') {
+            throw("WebSocket binary sub-protocol requested but not supported");
+        }
+        if (typeof(protocols) === "object") {
+            for (var i = 0; i < protocols.length; i++) {
+                if (protocols[i] === 'binary') {
+                    throw("WebSocket binary sub-protocol requested but not supported");
+                }
+            }
+        }
+    }
+
+    return protocols;
 }
 
-function open(uri) {
-    init();
+function open(uri, protocols) {
+    protocols = init(protocols);
 
     if (test_mode) {
         websocket = {};