[fix] Manage bookkeeping for incoming requests to the underlying sockets behind reverse proxied websocket events. Only use the appropriate variables in the closure scope of the upgrade event from this bookkeeping

Author: indexzero

lib/node-http-proxy.js

@@ -530,24 +530,30 @@ HttpProxy.prototype.proxyWebSocketRequest = function (req, socket, head, options
     }
   }
 
-  function onUpgrade(reverseProxy) {
+  function onUpgrade(out, reverseProxy) {
+    if (!out) {
+      reverseProxy.end();
+      socket.end();
+      return;
+    }
+    
     var listeners = {};
 
     // We're now connected to the server, so lets change server socket
     reverseProxy.on('data', listeners._r_data = function(data) {
       // Pass data to client
-      if (socket.writable) {
+      if (out.incoming.socket.writable) {
         try {
-          socket.write(data);
+          out.incoming.socket.write(data);
         } 
         catch (e) {
-          socket.end();
+          out.incoming.socket.end();
           reverseProxy.end();
         }
       }
     });
 
-    socket.on('data', listeners._data = function(data) {
+    out.incoming.socket.on('data', listeners._data = function(data) {
       // Pass data from client to server
       try {
         reverseProxy.write(data);
@@ -562,13 +568,13 @@ HttpProxy.prototype.proxyWebSocketRequest = function (req, socket, head, options
     function detach() {
       reverseProxy.removeListener('close', listeners._r_close);
       reverseProxy.removeListener('data', listeners._r_data);
-      socket.removeListener('data', listeners._data);
-      socket.removeListener('close', listeners._close);
+      out.incoming.socket.removeListener('data', listeners._data);
+      out.incoming.socket.removeListener('close', listeners._close);
     }
 
     // Hook disconnections
     reverseProxy.on('end', listeners._r_close = function() {
-      socket.end();
+      out.incoming.socket.end();
       detach();
     });
 
@@ -592,27 +598,47 @@ HttpProxy.prototype.proxyWebSocketRequest = function (req, socket, head, options
   outgoing = {
     host: options.host,
     port: options.port,
-    agent: agent,
     method: 'GET',
     path: req.url,
-    headers: req.headers
+    headers: req.headers,
   };
 
   // Make the outgoing WebSocket request
-  var request = http.request(outgoing, function () { });
-  
-  // Not disconnect on update
-  agent.on('upgrade', function(request, remoteSocket, head) {
-    // Prepare socket
-    _socket(remoteSocket, true);
+  var request = agent.appendMessage(outgoing);
 
-    // Emit event
-    onUpgrade(remoteSocket);
-  });
+  //
+  // Here we set the incoming `req`, `socket` and `head` data to the outgoing
+  // request so that we can reuse this data later on in the closure scope
+  // available to the `upgrade` event. This bookkeeping is not tracked anywhere 
+  // in nodejs core and is **very** specific to proxying WebSockets.
+  //
+  request.agent = agent;
+  request.incoming = {
+    request: req,
+    socket: socket,
+    head: head
+  };
+  
+  //
+  // If the agent for this particular `host` and `port` combination
+  // is not already listening for the `upgrade` event, then do so once.
+  // This will force us not to disconnect. 
+  //
+  // In addition, it's important to note the closure scope here. Since
+  // there is no mapping of the 
+  //
+  if (!agent._events || agent._events['upgrade'].length === 0) {
+    agent.on('upgrade', function (out, remoteSocket, head) {
+      // Prepare socket
+      _socket(remoteSocket, true);
+      
+      // Emit event
+      onUpgrade(remoteSocket._httpMessage, remoteSocket);
+    });
+  }
 
-  var handshake;
   if (typeof request.socket !== 'undefined') {
-    request.socket.on('data', handshake = function(data) {
+    request.socket.on('data', function handshake (data) {
       // Handshaking
 
       // Ok, kind of harmfull part of code