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forgejo/vendor/github.com/go-macaron/gzip/gzip.go
2016-11-04 08:43:11 +01:00

121 lines
3.4 KiB
Go

// Copyright 2013 Martini Authors
// Copyright 2015 The Macaron Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"): you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations
// under the License.
package gzip
import (
"bufio"
"fmt"
"net"
"net/http"
"strings"
"github.com/klauspost/compress/gzip"
"gopkg.in/macaron.v1"
)
const (
_HEADER_ACCEPT_ENCODING = "Accept-Encoding"
_HEADER_CONTENT_ENCODING = "Content-Encoding"
_HEADER_CONTENT_LENGTH = "Content-Length"
_HEADER_CONTENT_TYPE = "Content-Type"
_HEADER_VARY = "Vary"
)
// Options represents a struct for specifying configuration options for the GZip middleware.
type Options struct {
// Compression level. Can be DefaultCompression(-1), ConstantCompression(-2)
// or any integer value between BestSpeed(1) and BestCompression(9) inclusive.
CompressionLevel int
}
func isCompressionLevelValid(level int) bool {
return level == gzip.DefaultCompression ||
level == gzip.ConstantCompression ||
(level >= gzip.BestSpeed && level <= gzip.BestCompression)
}
func prepareOptions(options []Options) Options {
var opt Options
if len(options) > 0 {
opt = options[0]
}
if !isCompressionLevelValid(opt.CompressionLevel) {
// For web content, level 4 seems to be a sweet spot.
opt.CompressionLevel = 4
}
return opt
}
// Gziper returns a Handler that adds gzip compression to all requests.
// Make sure to include the Gzip middleware above other middleware
// that alter the response body (like the render middleware).
func Gziper(options ...Options) macaron.Handler {
opt := prepareOptions(options)
return func(ctx *macaron.Context) {
if !strings.Contains(ctx.Req.Header.Get(_HEADER_ACCEPT_ENCODING), "gzip") {
return
}
headers := ctx.Resp.Header()
headers.Set(_HEADER_CONTENT_ENCODING, "gzip")
headers.Set(_HEADER_VARY, _HEADER_ACCEPT_ENCODING)
// We've made sure compression level is valid in prepareGzipOptions,
// no need to check same error again.
gz, err := gzip.NewWriterLevel(ctx.Resp, opt.CompressionLevel)
if err != nil {
panic(err.Error())
}
defer gz.Close()
gzw := gzipResponseWriter{gz, ctx.Resp}
ctx.Resp = gzw
ctx.MapTo(gzw, (*http.ResponseWriter)(nil))
// Check if render middleware has been registered,
// if yes, we need to modify ResponseWriter for it as well.
if _, ok := ctx.Render.(*macaron.DummyRender); !ok {
ctx.Render.SetResponseWriter(gzw)
}
ctx.Next()
// delete content length after we know we have been written to
gzw.Header().Del("Content-Length")
}
}
type gzipResponseWriter struct {
w *gzip.Writer
macaron.ResponseWriter
}
func (grw gzipResponseWriter) Write(p []byte) (int, error) {
if len(grw.Header().Get(_HEADER_CONTENT_TYPE)) == 0 {
grw.Header().Set(_HEADER_CONTENT_TYPE, http.DetectContentType(p))
}
return grw.w.Write(p)
}
func (grw gzipResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
hijacker, ok := grw.ResponseWriter.(http.Hijacker)
if !ok {
return nil, nil, fmt.Errorf("the ResponseWriter doesn't support the Hijacker interface")
}
return hijacker.Hijack()
}