[refactor] core proxy logic. all tests should be passing.

Author: Marak

lib/node-http-proxy/http-proxy.js

@@ -218,46 +218,24 @@ HttpProxy.prototype.proxyRequest = function (req, res, buffer) {
       return;
     }
 
-    //
-    // For each data `chunk` received from the `reverseProxy`
-    // `response` write it to the outgoing `res`.
-    // If the res socket has been killed already, then write()
-    // will throw. Nevertheless, try our best to end it nicely.
-    //
-    var paused = false;
-    response.on('data', function (chunk) {
-      if (req.method !== 'HEAD' && res.writable) {
-        try {
-          var flushed = res.write(chunk);
-        } 
-        catch (ex) {
-          console.error("res.write error: %s", ex.message);
-          
-          try { res.end() } 
-          catch (ex) { console.error("res.end error: %s", ex.message) }
-          
-          return;
-        }
-        
-        if (!flushed && !paused) {
-          paused = true;
-          response.pause();
-          res.once('drain', function () {
-            paused = false;
-            try { response.resume() } 
-            catch (er) { console.error("response.resume error: %s", er.message) }
-          });
-          
-          //
-          // Force the `drain` event in 100ms if it hasn't
-          // happened on its own. 
-          //          
-          setTimeout(function () {
-            res.emit('drain');
-          }, 100);
+
+    function ondata(chunk) {
+        if (res.writable) {
+          if (false === res.write(chunk) && response.pause) {
+            response.pause();
+          }
         }
       }
-    });
+
+    response.on('data', ondata);
+
+    function ondrain() {
+      if (response.readable && response.resume) {
+        response.resume();
+      }
+    }
+
+    res.on('drain', ondrain);
 
     //
     // When the `reverseProxy` `response` ends, end the