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// Copyright 2013 The Gorilla Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package handlers
import (
"compress/flate"
"compress/gzip"
"io"
"net/http"
"strings"
)
type compressResponseWriter struct {
io.Writer
http.ResponseWriter
http.Hijacker
}
func (w *compressResponseWriter) Header() http.Header {
return w.ResponseWriter.Header()
}
func (w *compressResponseWriter) Write(b []byte) (int, error) {
h := w.ResponseWriter.Header()
if h.Get("Content-Type") == "" {
h.Set("Content-Type", http.DetectContentType(b))
}
return w.Writer.Write(b)
}
// CompressHandler gzip compresses HTTP responses for clients that support it
// via the 'Accept-Encoding' header.
func CompressHandler(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
L:
for _, enc := range strings.Split(r.Header.Get("Accept-Encoding"), ",") {
switch strings.TrimSpace(enc) {
case "gzip":
w.Header().Set("Content-Encoding", "gzip")
w.Header().Add("Vary", "Accept-Encoding")
gw := gzip.NewWriter(w)
defer gw.Close()
h, hok := w.(http.Hijacker)
if !hok { /* w is not Hijacker... oh well... */
h = nil
}
w = &compressResponseWriter{
Writer: gw,
ResponseWriter: w,
Hijacker: h,
}
break L
case "deflate":
w.Header().Set("Content-Encoding", "deflate")
w.Header().Add("Vary", "Accept-Encoding")
fw, _ := flate.NewWriter(w, flate.DefaultCompression)
defer fw.Close()
h, hok := w.(http.Hijacker)
if !hok { /* w is not Hijacker... oh well... */
h = nil
}
w = &compressResponseWriter{
Writer: fw,
ResponseWriter: w,
Hijacker: h,
}
break L
}
}
h.ServeHTTP(w, r)
})
}
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