[fix] properly include port in host header with changeOrigin in all cases fixes http-party#750

Author: jcrugzz

lib/http-proxy/common.js

@@ -1,6 +1,7 @@
-var common = exports,
-    url    = require('url'),
-    extend = require('util')._extend;
+var common   = exports,
+    url      = require('url'),
+    extend   = require('util')._extend,
+    required = require('requires-port');
 
 var upgradeHeader = /(^|,)\s*upgrade\s*($|,)/i;
 /**
@@ -74,9 +75,11 @@ common.setupOutgoing = function(outgoing, options, req, forward) {
   outgoing.path = common.urlJoin(targetPath, outgoingPath);
 
   if (options.changeOrigin) {
-    outgoing.headers.host = outgoing.host;
+    outgoing.headers.host =
+      required(outgoing.port, options[forward || 'target'].protocol) && !hasPort(outgoing.host)
+        ? outgoing.host + ':' + outgoing.port
+        : outgoing.host;
   }
-
   return outgoing;
 };
 
@@ -161,3 +164,14 @@ common.urlJoin = function() {
 
   return retSegs.join('?')
 };
+
+/**
+ * Check the host and see if it potentially has a port in it (keep it simple)
+ *
+ * @returns {Boolean} Whether we have one or not
+ *
+ * @api private
+ */
+function hasPort(host) {
+  return !!~host.indexOf(':');
+};