updated websocket lib

vendor/github.com/gorilla/websocket/compression.go

@@ -0,0 +1,105 @@
+// Copyright 2017 The Gorilla WebSocket 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 websocket
+
+import (
+	"compress/flate"
+	"errors"
+	"io"
+	"strings"
+	"sync"
+)
+
+var (
+	flateWriterPool = sync.Pool{}
+)
+
+func decompressNoContextTakeover(r io.Reader) io.Reader {
+	const tail =
+	// Add four bytes as specified in RFC
+	"\x00\x00\xff\xff" +
+		// Add final block to squelch unexpected EOF error from flate reader.
+		"\x01\x00\x00\xff\xff"
+	return flate.NewReader(io.MultiReader(r, strings.NewReader(tail)))
+}
+
+func compressNoContextTakeover(w io.WriteCloser) (io.WriteCloser, error) {
+	tw := &truncWriter{w: w}
+	i := flateWriterPool.Get()
+	var fw *flate.Writer
+	var err error
+	if i == nil {
+		fw, err = flate.NewWriter(tw, 3)
+	} else {
+		fw = i.(*flate.Writer)
+		fw.Reset(tw)
+	}
+	return &flateWrapper{fw: fw, tw: tw}, err
+}
+
+// truncWriter is an io.Writer that writes all but the last four bytes of the
+// stream to another io.Writer.
+type truncWriter struct {
+	w io.WriteCloser
+	n int
+	p [4]byte
+}
+
+func (w *truncWriter) Write(p []byte) (int, error) {
+	n := 0
+
+	// fill buffer first for simplicity.
+	if w.n < len(w.p) {
+		n = copy(w.p[w.n:], p)
+		p = p[n:]
+		w.n += n
+		if len(p) == 0 {
+			return n, nil
+		}
+	}
+
+	m := len(p)
+	if m > len(w.p) {
+		m = len(w.p)
+	}
+
+	if nn, err := w.w.Write(w.p[:m]); err != nil {
+		return n + nn, err
+	}
+
+	copy(w.p[:], w.p[m:])
+	copy(w.p[len(w.p)-m:], p[len(p)-m:])
+	nn, err := w.w.Write(p[:len(p)-m])
+	return n + nn, err
+}
+
+type flateWrapper struct {
+	fw *flate.Writer
+	tw *truncWriter
+}
+
+func (w *flateWrapper) Write(p []byte) (int, error) {
+	if w.fw == nil {
+		return 0, errWriteClosed
+	}
+	return w.fw.Write(p)
+}
+
+func (w *flateWrapper) Close() error {
+	if w.fw == nil {
+		return errWriteClosed
+	}
+	err1 := w.fw.Flush()
+	flateWriterPool.Put(w.fw)
+	w.fw = nil
+	if w.tw.p != [4]byte{0, 0, 0xff, 0xff} {
+		return errors.New("websocket: internal error, unexpected bytes at end of flate stream")
+	}
+	err2 := w.tw.w.Close()
+	if err1 != nil {
+		return err1
+	}
+	return err2
+}