From 538e5006823b3ffa85806cb33d7770f32bb76d77 Mon Sep 17 00:00:00 2001
From: Frank Schroeder <frank.schroeder@gmail.com>
Date: Wed, 24 May 2017 19:32:33 +0200
Subject: [PATCH] Issue #300: GzipHandler should implement http.Hijacker

---
 proxy/gzip/gzip_handler.go | 39 +++++++++++++++++++++++++++-----------
 1 file changed, 28 insertions(+), 11 deletions(-)

diff --git a/proxy/gzip/gzip_handler.go b/proxy/gzip/gzip_handler.go
index 046eb5b14..42efd8884 100644
--- a/proxy/gzip/gzip_handler.go
+++ b/proxy/gzip/gzip_handler.go
@@ -8,8 +8,11 @@
 package gzip
 
 import (
+	"bufio"
 	"compress/gzip"
+	"errors"
 	"io"
+	"net"
 	"net/http"
 	"regexp"
 	"strings"
@@ -29,21 +32,35 @@ var gzipWriterPool = sync.Pool{
 	New: func() interface{} { return gzip.NewWriter(nil) },
 }
 
+type gzipHandler struct {
+	h            http.Handler
+	contentTypes *regexp.Regexp
+}
+
+func (h *gzipHandler) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	if hj, ok := h.h.(http.Hijacker); ok {
+		return hj.Hijack()
+	}
+	return nil, nil, errors.New("not a Hijacker")
+}
+
+func (h *gzipHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	w.Header().Add(headerVary, headerAcceptEncoding)
+
+	if acceptsGzip(r) {
+		gzWriter := NewGzipResponseWriter(w, h.contentTypes)
+		defer gzWriter.Close()
+		h.h.ServeHTTP(gzWriter, r)
+	} else {
+		h.h.ServeHTTP(w, r)
+	}
+}
+
 // NewGzipHandler wraps an existing handler to transparently gzip the response
 // body if the client supports it (via the Accept-Encoding header) and the
 // response Content-Type matches the contentTypes expression.
 func NewGzipHandler(h http.Handler, contentTypes *regexp.Regexp) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Add(headerVary, headerAcceptEncoding)
-
-		if acceptsGzip(r) {
-			gzWriter := NewGzipResponseWriter(w, contentTypes)
-			defer gzWriter.Close()
-			h.ServeHTTP(gzWriter, r)
-		} else {
-			h.ServeHTTP(w, r)
-		}
-	})
+	return &gzipHandler{h, contentTypes}
 }
 
 type GzipResponseWriter struct {