net/http/gzip/gzip.go

   1 package gzip
   2
   3 import (
   4         "bufio"
   5         "compress/gzip"
   6         "errors"
   7         "io"
   8         "net"
   9         "net/http"
  10         "strings"
  11         "sync"
  12 )
  13
  14 var pool = sync.Pool{
  15         New: func() interface{} {
  16                 w, _ := gzip.NewWriterLevel(nil, gzip.BestSpeed) // #nosec
  17                 return w
  18         },
  19 }
  20
  21 func getWriter(w io.Writer) *gzip.Writer {
  22         gz := pool.Get().(*gzip.Writer)
  23         gz.Reset(w)
  24         return gz
  25 }
  26
  27 type Handler struct {
  28         Handler http.Handler
  29 }
  30
  31 func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
  32         w.Header().Add("Vary", "Accept-Encoding")
  33         if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
  34                 h.Handler.ServeHTTP(w, r)
  35                 return
  36         }
  37         w.Header().Set("Content-Encoding", "gzip")
  38         gz := getWriter(w)
  39         w = &responseWriter{gz, w}
  40         h.Handler.ServeHTTP(w, r)
  41         gz.Close()
  42         pool.Put(gz)
  43 }
  44
  45 type responseWriter struct {
  46         w                   io.Writer // w wraps only method Write
  47         http.ResponseWriter           // embedded for the other methods
  48 }
  49
  50 var _ http.ResponseWriter = (*responseWriter)(nil)
  51 var _ http.Hijacker = (*responseWriter)(nil)
  52
  53 func (w *responseWriter) Write(p []byte) (int, error) { return w.w.Write(p) }
  54
  55 func (w *responseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
  56         h, ok := w.ResponseWriter.(http.Hijacker)
  57         if !ok {
  58                 return nil, nil, errors.New("not a hijacker")
  59         }
  60         return h.Hijack()
  61 }