Merge pull request #11 from slimsag/master

Add WebsocketProxy.Director optional function to forward additional headers

Author: rjeczalik

.travis.yml

@@ -1,2 +1,2 @@
 language: go
-go: 1.2
+go: 1.8

websocketproxy.go

@@ -27,6 +27,11 @@ var (
 // WebsocketProxy is an HTTP Handler that takes an incoming WebSocket
 // connection and proxies it to another server.
 type WebsocketProxy struct {
+	// Director, if non-nil, is a function that may copy additional request
+	// headers from the incoming WebSocket connection into the output headers
+	// which will be forwarded to another server.
+	Director func(incoming *http.Request, out http.Header)
+
 	// Backend returns the backend URL which the proxy uses to reverse proxy
 	// the incoming WebSocket connection. Request is the initial incoming and
 	// unmodified request.
@@ -118,6 +123,12 @@ func (w *WebsocketProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		requestHeader.Set("X-Forwarded-Proto", "https")
 	}
 
+	// Enable the director to copy any additional headers it desires for
+	// forwarding to the remote server.
+	if w.Director != nil {
+		w.Director(req, requestHeader)
+	}
+
 	// Connect to the backend URL, also pass the headers we get from the requst
 	// together with the Forwarded headers we prepared above.
 	// TODO: support multiplexing on the same backend connection instead of