Bump Gorilla Handlers to v1.5.1.

Signed-off-by: olegburov <oleg.burov@outlook.com>

vendor/github.com/gorilla/handlers/compress.go

@@ -10,75 +10,134 @@ import (
 	"io"
 	"net/http"
 	"strings"
+
+	"github.com/felixge/httpsnoop"
 )
 
+const acceptEncoding string = "Accept-Encoding"
+
 type compressResponseWriter struct {
-	io.Writer
-	http.ResponseWriter
-	http.Hijacker
+	compressor io.Writer
+	w          http.ResponseWriter
 }
 
-func (w *compressResponseWriter) Header() http.Header {
-	return w.ResponseWriter.Header()
+func (cw *compressResponseWriter) WriteHeader(c int) {
+	cw.w.Header().Del("Content-Length")
+	cw.w.WriteHeader(c)
 }
 
-func (w *compressResponseWriter) Write(b []byte) (int, error) {
-	h := w.ResponseWriter.Header()
+func (cw *compressResponseWriter) Write(b []byte) (int, error) {
+	h := cw.w.Header()
 	if h.Get("Content-Type") == "" {
 		h.Set("Content-Type", http.DetectContentType(b))
 	}
+	h.Del("Content-Length")
 
-	return w.Writer.Write(b)
+	return cw.compressor.Write(b)
+}
+
+func (cw *compressResponseWriter) ReadFrom(r io.Reader) (int64, error) {
+	return io.Copy(cw.compressor, r)
+}
+
+type flusher interface {
+	Flush() error
+}
+
+func (w *compressResponseWriter) Flush() {
+	// Flush compressed data if compressor supports it.
+	if f, ok := w.compressor.(flusher); ok {
+		f.Flush()
+	}
+	// Flush HTTP response.
+	if f, ok := w.w.(http.Flusher); ok {
+		f.Flush()
+	}
 }
 
 // CompressHandler gzip compresses HTTP responses for clients that support it
 // via the 'Accept-Encoding' header.
+//
+// Compressing TLS traffic may leak the page contents to an attacker if the
+// page contains user input: http://security.stackexchange.com/a/102015/12208
 func CompressHandler(h http.Handler) http.Handler {
+	return CompressHandlerLevel(h, gzip.DefaultCompression)
+}
+
+// CompressHandlerLevel gzip compresses HTTP responses with specified compression level
+// for clients that support it via the 'Accept-Encoding' header.
+//
+// The compression level should be gzip.DefaultCompression, gzip.NoCompression,
+// or any integer value between gzip.BestSpeed and gzip.BestCompression inclusive.
+// gzip.DefaultCompression is used in case of invalid compression level.
+func CompressHandlerLevel(h http.Handler, level int) http.Handler {
+	if level < gzip.DefaultCompression || level > gzip.BestCompression {
+		level = gzip.DefaultCompression
+	}
+
+	const (
+		gzipEncoding  = "gzip"
+		flateEncoding = "deflate"
+	)
+
 	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
+		// detect what encoding to use
+		var encoding string
+		for _, curEnc := range strings.Split(r.Header.Get(acceptEncoding), ",") {
+			curEnc = strings.TrimSpace(curEnc)
+			if curEnc == gzipEncoding || curEnc == flateEncoding {
+				encoding = curEnc
+				break
 			}
 		}
 
+		// always add Accept-Encoding to Vary to prevent intermediate caches corruption
+		w.Header().Add("Vary", acceptEncoding)
+
+		// if we weren't able to identify an encoding we're familiar with, pass on the
+		// request to the handler and return
+		if encoding == "" {
+			h.ServeHTTP(w, r)
+			return
+		}
+
+		if r.Header.Get("Upgrade") != "" {
+			h.ServeHTTP(w, r)
+			return
+		}
+
+		// wrap the ResponseWriter with the writer for the chosen encoding
+		var encWriter io.WriteCloser
+		if encoding == gzipEncoding {
+			encWriter, _ = gzip.NewWriterLevel(w, level)
+		} else if encoding == flateEncoding {
+			encWriter, _ = flate.NewWriter(w, level)
+		}
+		defer encWriter.Close()
+
+		w.Header().Set("Content-Encoding", encoding)
+		r.Header.Del(acceptEncoding)
+
+		cw := &compressResponseWriter{
+			w:          w,
+			compressor: encWriter,
+		}
+
+		w = httpsnoop.Wrap(w, httpsnoop.Hooks{
+			Write: func(httpsnoop.WriteFunc) httpsnoop.WriteFunc {
+				return cw.Write
+			},
+			WriteHeader: func(httpsnoop.WriteHeaderFunc) httpsnoop.WriteHeaderFunc {
+				return cw.WriteHeader
+			},
+			Flush: func(httpsnoop.FlushFunc) httpsnoop.FlushFunc {
+				return cw.Flush
+			},
+			ReadFrom: func(rff httpsnoop.ReadFromFunc) httpsnoop.ReadFromFunc {
+				return cw.ReadFrom
+			},
+		})
+
 		h.ServeHTTP(w, r)
 	})
 }