fix: double compression.

glide.lock

@@ -1,4 +1,4 @@
-hash: cebc972cf87c4b0a8f86801f38750c51b09c8dee3bf62bb48f8eaa6ab7946352
+hash: df3bba260c0e5c3183741ab4aca2ae551a5c6d9ba11f4e05b90554a9ffad96ad
 updated: 2017-06-29T16:47:14.848940186+02:00
 imports:
 - name: cloud.google.com/go
@@ -320,7 +320,9 @@ imports:
 - name: github.com/mvdan/xurls
   version: db96455566f05ffe42bd6ac671f05eeb1152b45d
 - name: github.com/NYTimes/gziphandler
-  version: 22d4470af89e09998fc16b35029df973932df4ae
+  version: 316adfc72ed3b0157975917adf62ba2dc31842ce
+  repo: https://github.com/containous/gziphandler.git
+  vcs: git
 - name: github.com/ogier/pflag
   version: 45c278ab3607870051a2ea9040bb85fcb8557481
 - name: github.com/opencontainers/runc

glide.yaml

@@ -87,6 +87,8 @@ import:
   vcs: git
 - package: github.com/abbot/go-http-auth
 - package: github.com/NYTimes/gziphandler
+  repo: https://github.com/containous/gziphandler.git
+  vcs: git
 - package: github.com/docker/leadership
 - package: github.com/satori/go.uuid
   version: ^1.1.0

middlewares/compress.go

@@ -1,13 +1,11 @@
 package middlewares
 
 import (
+	"compress/gzip"
 	"net/http"
 
 	"github.com/NYTimes/gziphandler"
-)
-
-const (
-	contentEncodingHeader = "Content-Encoding"
+	"github.com/containous/traefik/log"
 )
 
 // Compress is a middleware that allows redirection
@@ -15,17 +13,13 @@ type Compress struct{}
 
 // ServerHTTP is a function used by Negroni
 func (c *Compress) ServeHTTP(rw http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
-	if isEncoded(r.Header) {
-		next.ServeHTTP(rw, r)
-	} else {
-		newGzipHandler := gziphandler.GzipHandler(next)
-		newGzipHandler.ServeHTTP(rw, r)
-	}
+	gzipHandler(next).ServeHTTP(rw, r)
 }
 
-func isEncoded(headers http.Header) bool {
-	header := headers.Get(contentEncodingHeader)
-	// According to https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Encoding,
-	// content is not encoded if the header 'Content-Encoding' is empty or equals to 'identity'.
-	return header != "" && header != "identity"
+func gzipHandler(h http.Handler) http.Handler {
+	wrapper, err := gziphandler.NewGzipHandler(gzip.DefaultCompression, gziphandler.DefaultMinSize, &gziphandler.GzipResponseWriterWrapper{})
+	if err != nil {
+		log.Error(err)
+	}
+	return wrapper(h)
 }

middlewares/compress_test.go

@@ -1,36 +1,39 @@
 package middlewares
 
 import (
+	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
 	"testing"
 
 	"github.com/NYTimes/gziphandler"
+	"github.com/codegangsta/negroni"
 	"github.com/containous/traefik/testhelpers"
 	"github.com/stretchr/testify/assert"
 )
 
 const (
 	acceptEncodingHeader  = "Accept-Encoding"
+	contentEncodingHeader = "Content-Encoding"
 	varyHeader            = "Vary"
-	gzip                 = "gzip"
+	gzipValue             = "gzip"
 )
 
 func TestShouldCompressWhenNoContentEncodingHeader(t *testing.T) {
 	handler := &Compress{}
 
 	req := testhelpers.MustNewRequest(http.MethodGet, "http://localhost", nil)
-	req.Header.Add(acceptEncodingHeader, gzip)
+	req.Header.Add(acceptEncodingHeader, gzipValue)
 
 	baseBody := generateBytes(gziphandler.DefaultMinSize)
 	next := func(rw http.ResponseWriter, r *http.Request) {
 		rw.Write(baseBody)
 	}
-	rw := httptest.NewRecorder()
 
+	rw := httptest.NewRecorder()
 	handler.ServeHTTP(rw, req, next)
 
-	assert.Equal(t, gzip, rw.Header().Get(contentEncodingHeader))
+	assert.Equal(t, gzipValue, rw.Header().Get(contentEncodingHeader))
 	assert.Equal(t, acceptEncodingHeader, rw.Header().Get(varyHeader))
 
 	if assert.ObjectsAreEqualValues(rw.Body.Bytes(), baseBody) {
@@ -42,28 +45,105 @@ func TestShouldNotCompressWhenContentEncodingHeader(t *testing.T) {
 	handler := &Compress{}
 
 	req := testhelpers.MustNewRequest(http.MethodGet, "http://localhost", nil)
-	req.Header.Add(acceptEncodingHeader, gzip)
-	req.Header.Add(contentEncodingHeader, gzip)
-
-	baseBody := generateBytes(gziphandler.DefaultMinSize)
+	req.Header.Add(acceptEncodingHeader, gzipValue)
 
+	fakeCompressedBody := generateBytes(gziphandler.DefaultMinSize)
 	next := func(rw http.ResponseWriter, r *http.Request) {
-		rw.Write(baseBody)
+		rw.Header().Add(contentEncodingHeader, gzipValue)
+		rw.Header().Add(varyHeader, acceptEncodingHeader)
+		rw.Write(fakeCompressedBody)
 	}
 
 	rw := httptest.NewRecorder()
 	handler.ServeHTTP(rw, req, next)
 
-	assert.Equal(t, "", rw.Header().Get(contentEncodingHeader))
-	assert.Equal(t, "", rw.Header().Get(varyHeader))
+	assert.Equal(t, gzipValue, rw.Header().Get(contentEncodingHeader))
+	assert.Equal(t, acceptEncodingHeader, rw.Header().Get(varyHeader))
 
-	assert.EqualValues(t, rw.Body.Bytes(), baseBody)
+	assert.EqualValues(t, rw.Body.Bytes(), fakeCompressedBody)
+}
+
+func TestShouldNotCompressWhenNoAcceptEncodingHeader(t *testing.T) {
+	handler := &Compress{}
+
+	req := testhelpers.MustNewRequest(http.MethodGet, "http://localhost", nil)
+
+	fakeBody := generateBytes(gziphandler.DefaultMinSize)
+	next := func(rw http.ResponseWriter, r *http.Request) {
+		rw.Write(fakeBody)
+	}
+
+	rw := httptest.NewRecorder()
+	handler.ServeHTTP(rw, req, next)
+
+	assert.Empty(t, rw.Header().Get(contentEncodingHeader))
+	assert.EqualValues(t, rw.Body.Bytes(), fakeBody)
+}
+
+func TestIntegrationShouldNotCompressWhenContentAlreadyCompressed(t *testing.T) {
+	fakeCompressedBody := generateBytes(100000)
+
+	handler := func(rw http.ResponseWriter, r *http.Request) {
+		rw.Header().Add(contentEncodingHeader, gzipValue)
+		rw.Header().Add(varyHeader, acceptEncodingHeader)
+		rw.Write(fakeCompressedBody)
+	}
+
+	comp := &Compress{}
+
+	negro := negroni.New(comp)
+	negro.UseHandlerFunc(handler)
+	ts := httptest.NewServer(negro)
+	defer ts.Close()
+
+	client := &http.Client{}
+	req := testhelpers.MustNewRequest(http.MethodGet, ts.URL, nil)
+	req.Header.Add(acceptEncodingHeader, gzipValue)
+
+	resp, err := client.Do(req)
+	assert.NoError(t, err, "there should be no error")
+
+	assert.Equal(t, gzipValue, resp.Header.Get(contentEncodingHeader))
+	assert.Equal(t, acceptEncodingHeader, resp.Header.Get(varyHeader))
+
+	body, err := ioutil.ReadAll(resp.Body)
+	assert.EqualValues(t, fakeCompressedBody, body)
+}
+
+func TestIntegrationShouldCompressWhenAcceptEncodingHeaderIsPresent(t *testing.T) {
+	fakeBody := generateBytes(100000)
+
+	handler := func(rw http.ResponseWriter, r *http.Request) {
+		rw.Write(fakeBody)
+	}
+
+	comp := &Compress{}
+
+	negro := negroni.New(comp)
+	negro.UseHandlerFunc(handler)
+	ts := httptest.NewServer(negro)
+	defer ts.Close()
+
+	client := &http.Client{}
+	req := testhelpers.MustNewRequest(http.MethodGet, ts.URL, nil)
+	req.Header.Add(acceptEncodingHeader, gzipValue)
+
+	resp, err := client.Do(req)
+	assert.NoError(t, err, "there should be no error")
+
+	assert.Equal(t, gzipValue, resp.Header.Get(contentEncodingHeader))
+	assert.Equal(t, acceptEncodingHeader, resp.Header.Get(varyHeader))
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if assert.ObjectsAreEqualValues(body, fakeBody) {
+		assert.Fail(t, "expected a compressed body", "got %v", body)
+	}
 }
 
 func generateBytes(len int) []byte {
 	var value []byte
 	for i := 0; i < len; i++ {
-		value = append(value, 0x61)
+		value = append(value, 0x61+byte(i))
 	}
 	return value
 }

vendor/github.com/NYTimes/gziphandler/gzip.go

@@ -3,6 +3,7 @@ package gziphandler
 import (
 	"bufio"
 	"compress/gzip"
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -97,6 +98,7 @@ func (w *GzipResponseWriter) Write(b []byte) (int, error) {
 	}
 
 	// Save the write into a buffer for later use in GZIP responseWriter (if content is long enough) or at close with regular responseWriter.
+	// On the first write, w.buf changes from nil to a valid slice
 	w.buf = append(w.buf, b...)
 
 	// If the global writes are bigger than the minSize, compression is enable.
@@ -122,7 +124,9 @@ func (w *GzipResponseWriter) startGzip() error {
 	w.Header().Del(contentLength)
 
 	// Write the header to gzip response.
-	w.writeHeader()
+	if w.code != 0 {
+		w.ResponseWriter.WriteHeader(w.code)
+	}
 
 	// Initialize the GZIP response.
 	w.init()
@@ -146,14 +150,6 @@ func (w *GzipResponseWriter) WriteHeader(code int) {
 	w.code = code
 }
 
-// writeHeader uses the saved code to send it to the ResponseWriter.
-func (w *GzipResponseWriter) writeHeader() {
-	if w.code == 0 {
-		w.code = http.StatusOK
-	}
-	w.ResponseWriter.WriteHeader(w.code)
-}
-
 // init graps a new gzip writer from the gzipWriterPool and writes the correct
 // content encoding header.
 func (w *GzipResponseWriter) init() {
@@ -166,19 +162,18 @@ func (w *GzipResponseWriter) init() {
 
 // Close will close the gzip.Writer and will put it back in the gzipWriterPool.
 func (w *GzipResponseWriter) Close() error {
-	// Buffer not nil means the regular response must be returned.
+	if w.gw == nil {
+		// Gzip not trigged yet, write out regular response.
+		if w.code != 0 {
+			w.ResponseWriter.WriteHeader(w.code)
+		}
 		if w.buf != nil {
-		w.writeHeader()
-		// Make the write into the regular response.
 			_, writeErr := w.ResponseWriter.Write(w.buf)
 			// Returns the error if any at write.
 			if writeErr != nil {
 				return fmt.Errorf("gziphandler: write to regular responseWriter at close gets error: %q", writeErr.Error())
 			}
 		}
-
-	// If the GZIP responseWriter is not set no needs to close it.
-	if w.gw == nil {
 		return nil
 	}
 
@@ -236,12 +231,22 @@ func NewGzipLevelHandler(level int) (func(http.Handler) http.Handler, error) {
 // NewGzipLevelAndMinSize behave as NewGzipLevelHandler except it let the caller
 // specify the minimum size before compression.
 func NewGzipLevelAndMinSize(level, minSize int) (func(http.Handler) http.Handler, error) {
+	return NewGzipHandler(level, minSize, &GzipResponseWriter{})
+}
+
+// NewGzipHandler behave as NewGzipLevelHandler except it let the caller
+// specify the minimum size before compression and a GzipWriter.
+func NewGzipHandler(level, minSize int, gw GzipWriter) (func(http.Handler) http.Handler, error) {
 	if level != gzip.DefaultCompression && (level < gzip.BestSpeed || level > gzip.BestCompression) {
 		return nil, fmt.Errorf("invalid compression level requested: %d", level)
 	}
 	if minSize < 0 {
-		return nil, fmt.Errorf("minimum size must be more than zero")
+		return nil, errors.New("minimum size must be more than zero")
 	}
+	if gw == nil {
+		return nil, errors.New("the GzipWriter must be defined")
+	}
+
 	return func(h http.Handler) http.Handler {
 		index := poolIndex(level)
 
@@ -249,13 +254,9 @@ func NewGzipLevelAndMinSize(level, minSize int) (func(http.Handler) http.Handler
 			w.Header().Add(vary, acceptEncoding)
 
 			if acceptsGzip(r) {
-				gw := &GzipResponseWriter{
-					ResponseWriter: w,
-					index:          index,
-					minSize:        minSize,
-
-					buf: []byte{},
-				}
+				gw.SetResponseWriter(w)
+				gw.setIndex(index)
+				gw.setMinSize(minSize)
 				defer gw.Close()
 
 				h.ServeHTTP(gw, r)

vendor/github.com/NYTimes/gziphandler/wrapper.go

@@ -0,0 +1,58 @@
+package gziphandler
+
+import (
+	"bufio"
+	"net"
+	"net/http"
+)
+
+const (
+	contentEncodingHeader = "Content-Encoding"
+)
+
+// ----------
+
+// http.ResponseWriter
+// http.Hijacker
+type GzipWriter interface {
+	Header() http.Header
+	Write([]byte) (int, error)
+	WriteHeader(int)
+	Hijack() (net.Conn, *bufio.ReadWriter, error)
+	Close() error
+	SetResponseWriter(http.ResponseWriter)
+	setIndex(int)
+	setMinSize(int)
+}
+
+func (w *GzipResponseWriter) SetResponseWriter(rw http.ResponseWriter) {
+	w.ResponseWriter = rw
+}
+
+func (w *GzipResponseWriter) setIndex(index int) {
+	w.index = index
+}
+
+func (w *GzipResponseWriter) setMinSize(minSize int) {
+	w.minSize = minSize
+}
+
+// --------
+
+type GzipResponseWriterWrapper struct {
+	GzipResponseWriter
+}
+
+func (g *GzipResponseWriterWrapper) Write(b []byte) (int, error) {
+	if g.gw == nil && isEncoded(g.Header()) {
+		return g.ResponseWriter.Write(b)
+	}
+	return g.GzipResponseWriter.Write(b)
+}
+
+func isEncoded(headers http.Header) bool {
+	header := headers.Get(contentEncodingHeader)
+	// According to https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Encoding,
+	// content is not encoded if the header 'Content-Encoding' is empty or equals to 'identity'.
+	return header != "" && header != "identity"
+}