[refactor] Improved event handler cleanup

Author: Marak

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

@@ -236,24 +236,46 @@ HttpProxy.prototype.proxyRequest = function (req, res, buffer) {
 
     res.on('drain', ondrain);
 
-    //
-    // When the `reverseProxy` `response` ends, end the
-    // corresponding outgoing `res` unless we have entered
-    // an error state. In which case, assume `res.end()` has
-    // already been called and the 'error' event listener
-    // removed.
-    //
-    response.on('end', function () {
-      if (!errState) {
-        reverseProxy.removeListener('error', proxyError);
-        
-        try { res.end() }
-        catch (ex) { console.error("res.end error: %s", ex.message) }
-        
-        // Emit the `end` event now that we have completed proxying
-        self.emit('end', req, res);
-      }
-    });
+    function onend() {
+      cleanup();
+      res.end();
+    }
+
+    function onclose() {
+      cleanup();
+      res.destroy();
+    }
+
+    response.on('close', onclose);
+    response.on('end', onend);
+
+    response.on('error', proxyError);
+    res.on('error', proxyError);
+
+
+    function cleanup() {
+      response.removeListener('data', ondata);
+      res.removeListener('drain', ondrain);
+
+      response.removeListener('end', onend);
+      response.removeListener('close', onclose);
+
+      response.removeListener('error', proxyError);
+      res.removeListener('error', proxyError);
+
+      response.removeListener('end', cleanup);
+      response.removeListener('close', cleanup);
+
+      res.removeListener('end', cleanup);
+      res.removeListener('close', cleanup);
+    }
+
+    response.on('end', cleanup);
+    response.on('close', cleanup);
+
+    res.on('end', cleanup);
+    res.on('close', cleanup);
+
   });
 
   //