From 5a5a41081165435867b4e5d3a2a269d099d21c56 Mon Sep 17 00:00:00 2001
From: Sam Alba <sam.alba@gmail.com>
Date: Thu, 21 Mar 2013 16:44:32 -0700
Subject: [PATCH] Prevent headers to be sent twice

---
 lib/node-http-proxy/http-proxy.js | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/lib/node-http-proxy/http-proxy.js b/lib/node-http-proxy/http-proxy.js
index 1a893f8de..25343bcb5 100644
--- a/lib/node-http-proxy/http-proxy.js
+++ b/lib/node-http-proxy/http-proxy.js
@@ -325,10 +325,12 @@ HttpProxy.prototype.proxyRequest = function (req, res, buffer) {
     }
 
     // Set the headers of the client response
-    Object.keys(response.headers).forEach(function (key) {
-      res.setHeader(key, response.headers[key]);
-    });
-    res.writeHead(response.statusCode);
+    if (res.sentHeaders !== true) {
+        Object.keys(response.headers).forEach(function (key) {
+            res.setHeader(key, response.headers[key]);
+        });
+        res.writeHead(response.statusCode);
+    }
 
     function ondata(chunk) {
       if (res.writable) {