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package restful
// Copyright 2013 Ernest Micklei. All rights reserved.
// Use of this source code is governed by a license
// that can be found in the LICENSE file.
import (
"bufio"
"compress/gzip"
"compress/zlib"
"errors"
"io"
"net"
"net/http"
"strings"
)
// OBSOLETE : use restful.DefaultContainer.EnableContentEncoding(true) to change this setting.
var EnableContentEncoding = false
// CompressingResponseWriter is a http.ResponseWriter that can perform content encoding (gzip and zlib)
type CompressingResponseWriter struct {
writer http.ResponseWriter
compressor io.WriteCloser
encoding string
}
// Header is part of http.ResponseWriter interface
func (c *CompressingResponseWriter) Header() http.Header {
return c.writer.Header()
}
// WriteHeader is part of http.ResponseWriter interface
func (c *CompressingResponseWriter) WriteHeader(status int) {
c.writer.WriteHeader(status)
}
// Write is part of http.ResponseWriter interface
// It is passed through the compressor
func (c *CompressingResponseWriter) Write(bytes []byte) (int, error) {
if c.isCompressorClosed() {
return -1, errors.New("Compressing error: tried to write data using closed compressor")
}
return c.compressor.Write(bytes)
}
// CloseNotify is part of http.CloseNotifier interface
func (c *CompressingResponseWriter) CloseNotify() <-chan bool {
return c.writer.(http.CloseNotifier).CloseNotify()
}
// Close the underlying compressor
func (c *CompressingResponseWriter) Close() error {
if c.isCompressorClosed() {
return errors.New("Compressing error: tried to close already closed compressor")
}
c.compressor.Close()
if ENCODING_GZIP == c.encoding {
currentCompressorProvider.ReleaseGzipWriter(c.compressor.(*gzip.Writer))
}
if ENCODING_DEFLATE == c.encoding {
currentCompressorProvider.ReleaseZlibWriter(c.compressor.(*zlib.Writer))
}
// gc hint needed?
c.compressor = nil
return nil
}
func (c *CompressingResponseWriter) isCompressorClosed() bool {
return nil == c.compressor
}
// Hijack implements the Hijacker interface
// This is especially useful when combining Container.EnabledContentEncoding
// in combination with websockets (for instance gorilla/websocket)
func (c *CompressingResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
hijacker, ok := c.writer.(http.Hijacker)
if !ok {
return nil, nil, errors.New("ResponseWriter doesn't support Hijacker interface")
}
return hijacker.Hijack()
}
// WantsCompressedResponse reads the Accept-Encoding header to see if and which encoding is requested.
func wantsCompressedResponse(httpRequest *http.Request) (bool, string) {
header := httpRequest.Header.Get(HEADER_AcceptEncoding)
gi := strings.Index(header, ENCODING_GZIP)
zi := strings.Index(header, ENCODING_DEFLATE)
// use in order of appearance
if gi == -1 {
return zi != -1, ENCODING_DEFLATE
} else if zi == -1 {
return gi != -1, ENCODING_GZIP
} else {
if gi < zi {
return true, ENCODING_GZIP
}
return true, ENCODING_DEFLATE
}
}
// NewCompressingResponseWriter create a CompressingResponseWriter for a known encoding = {gzip,deflate}
func NewCompressingResponseWriter(httpWriter http.ResponseWriter, encoding string) (*CompressingResponseWriter, error) {
httpWriter.Header().Set(HEADER_ContentEncoding, encoding)
c := new(CompressingResponseWriter)
c.writer = httpWriter
var err error
if ENCODING_GZIP == encoding {
w := currentCompressorProvider.AcquireGzipWriter()
w.Reset(httpWriter)
c.compressor = w
c.encoding = ENCODING_GZIP
} else if ENCODING_DEFLATE == encoding {
w := currentCompressorProvider.AcquireZlibWriter()
w.Reset(httpWriter)
c.compressor = w
c.encoding = ENCODING_DEFLATE
} else {
return nil, errors.New("Unknown encoding:" + encoding)
}
return c, err
}
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