Issue #15: noVNC falls behind.

noVNC was never processing more than one framebufferUpdate message per
onmessage event. If noVNC receives an incomplete framebufferUpdate and
then receives the rest of the framebufferUpdate plus another complete
framebufferUpdate, then it will fall permanently behind.

If there is more to process after a completed framebufferUpdate, then
execute normal_msg again.

All the render routines must return false if there is not enough data
in the receive queue to process their current update, and true
otherwise.

include/rfb.js

@@ -509,7 +509,7 @@ normal_msg: function () {
     }
     switch (msg_type) {
     case 0:  // FramebufferUpdate
-        ret = RFB.framebufferUpdate();
+        ret = RFB.framebufferUpdate(); // false means need more data
         break;
     case 1:  // SetColourMapEntries
         Util.Debug("SetColourMapEntries");
@@ -587,7 +587,13 @@ framebufferUpdate: function() {
         }
     }
 
-    while ((FBU.rects > 0) && (RQ.length >= FBU.bytes)) {
+    while (FBU.rects > 0) {
+        if (RFB.state !== "normal") {
+            return false;
+        }
+        if (RQ.length < FBU.bytes) {
+            return false;
+        }
         if (FBU.bytes === 0) {
             if (RQ.length < 12) {
                 //Util.Debug("   waiting for rect header bytes");
@@ -624,6 +630,7 @@ framebufferUpdate: function() {
         last_bytes = RQ.length;
         last_rects = FBU.rects;
 
+        // false ret means need more data
         ret = RFB.encHandlers[FBU.encoding]();
 
         now = (new Date()).getTime();
@@ -662,8 +669,6 @@ framebufferUpdate: function() {
                 timing.fbu_rt_start = 0;
             }
         }
-
-        if (RFB.state !== "normal") { return true; }
     }
     return ret;
 },
@@ -684,7 +689,7 @@ display_raw: function () {
     if (RQ.length < FBU.bytes) {
         //Util.Debug("   waiting for " +
         //           (FBU.bytes - RQ.length) + " RAW bytes");
-        return;
+        return false;
     }
     cur_y = FBU.y + (FBU.height - FBU.lines);
     cur_height = Math.min(FBU.lines,
@@ -699,6 +704,7 @@ display_raw: function () {
         FBU.rects -= 1;
         FBU.bytes = 0;
     }
+    return true;
 },
 
 display_copy_rect: function () {
@@ -709,13 +715,14 @@ display_copy_rect: function () {
     if (RQ.length < 4) {
         //Util.Debug("   waiting for " +
         //           (FBU.bytes - RQ.length) + " COPYRECT bytes");
-        return;
+        return false;
     }
     old_x = RQ.shift16();
     old_y = RQ.shift16();
     Canvas.copyImage(old_x, old_y, FBU.x, FBU.y, FBU.width, FBU.height);
     FBU.rects -= 1;
     FBU.bytes = 0;
+    return true;
 },
 
 display_rre: function () {
@@ -725,7 +732,7 @@ display_rre: function () {
         if (RQ.length < 4 + RFB.fb_Bpp) {
             //Util.Debug("   waiting for " +
             //           (4 + RFB.fb_Bpp - RQ.length) + " RRE bytes");
-            return;
+            return false;
         }
         FBU.subrects = RQ.shift32();
         color = RQ.shiftBytes(RFB.fb_Bpp); // Background
@@ -751,6 +758,7 @@ display_rre: function () {
         FBU.bytes = 0;
     }
     //Util.Debug("<< display_rre, FBU.bytes: " + FBU.bytes);
+    return true;
 },
 
 display_hextile: function() {
@@ -771,14 +779,14 @@ display_hextile: function() {
         FBU.bytes = 1;
         if (RQ.length < FBU.bytes) {
             //Util.Debug("   waiting for HEXTILE subencoding byte");
-            return;
+            return false;
         }
         subencoding = RQ[0];  // Peek
         if (subencoding > 30) { // Raw
             RFB.updateState('failed',
                     "Disconnected: illegal hextile subencoding " + subencoding);
             //Util.Debug("RQ.slice(0,30):" + RQ.slice(0,30));
-            return;
+            return false;
         }
         subrects = 0;
         cur_tile = FBU.total_tiles - FBU.tiles;
@@ -805,7 +813,7 @@ display_hextile: function() {
                 if (RQ.length < FBU.bytes) {
                     /* Wait for subrects byte */
                     //Util.Debug("   waiting for hextile subrects header byte");
-                    return;
+                    return false;
                 }
                 subrects = RQ[FBU.bytes-1]; // Peek
                 if (subencoding & 0x10) { // SubrectsColoured
@@ -827,7 +835,7 @@ display_hextile: function() {
         if (RQ.length < FBU.bytes) {
             //Util.Debug("   waiting for " +
             //           (FBU.bytes - RQ.length) + " hextile bytes");
-            return;
+            return false;
         }
 
         /* We know the encoding and have a whole tile */
@@ -889,6 +897,7 @@ display_hextile: function() {
     }
 
     //Util.Debug("<< display_hextile");
+    return true;
 },
 
 
@@ -904,7 +913,7 @@ display_tight_png: function() {
     FBU.bytes = 1; // compression-control byte
     if (RQ.length < FBU.bytes) {
         Util.Debug("   waiting for TIGHT compression-control byte");
-        return;
+        return false;
     }
 
     // Get 'compact length' header and data size
@@ -938,7 +947,7 @@ display_tight_png: function() {
 
     if (RQ.length < FBU.bytes) {
         Util.Debug("   waiting for TIGHT " + cmode + " bytes");
-        return;
+        return false;
     }
 
     //Util.Debug("   RQ.slice(0,20): " + RFB.RQ.slice(0,20) + " (" + RFB.RQ.length + ")");
@@ -957,7 +966,7 @@ display_tight_png: function() {
         FBU.bytes = 1 + clength[0] + clength[1]; // ctl + clength size + jpeg-data
         if (RQ.length < FBU.bytes) {
             Util.Debug("   waiting for TIGHT " + cmode + " bytes");
-            return;
+            return false;
         }
 
         // We have everything, render it
@@ -976,6 +985,7 @@ display_tight_png: function() {
     //Util.Debug("   ending RQ.length: " + RQ.length);
     //Util.Debug("   ending RQ.slice(0,20): " + RQ.slice(0,20));
     //Util.Debug("<< display_tight_png");
+    return true;
 },
 
 extract_data_uri : function (arr) {
@@ -1013,6 +1023,7 @@ set_desktopsize : function () {
     RFB.FBU.rects -= 1;
 
     Util.Debug("<< set_desktopsize");
+    return true;
 },
 
 set_cursor: function () {
@@ -1042,6 +1053,7 @@ set_cursor: function () {
     RFB.FBU.rects -= 1;
 
     //Util.Debug("<< set_cursor");
+    return true;
 },
 
 set_jpeg_quality : function () {
@@ -1238,16 +1250,15 @@ handle_message: function () {
         RFB.disconnect();
         break;
     case 'normal':
-        RFB.normal_msg();
-        /*
-        while (RFB.RQ.length > 0) {
-            if (RFB.normal_msg() && RFB.state === 'normal') {
-                Util.Debug("More to process");
+        while ((RFB.state === 'normal') && (RFB.RQ.length > 0)) {
+            if (RFB.normal_msg()) {
+                // true means we can continue processing
+                Util.Debug("More data to process");
             } else {
+                // false means we need more data
                 break;
             }
         }
-        */
         break;
     default:
         RFB.init_msg();