gitea/vendor/github.com/go-chi/chi/middleware/compress.go

400 lines
11 KiB
Go

package middleware
import (
"bufio"
"compress/flate"
"compress/gzip"
"errors"
"fmt"
"io"
"io/ioutil"
"net"
"net/http"
"strings"
"sync"
)
var defaultCompressibleContentTypes = []string{
"text/html",
"text/css",
"text/plain",
"text/javascript",
"application/javascript",
"application/x-javascript",
"application/json",
"application/atom+xml",
"application/rss+xml",
"image/svg+xml",
}
// Compress is a middleware that compresses response
// body of a given content types to a data format based
// on Accept-Encoding request header. It uses a given
// compression level.
//
// NOTE: make sure to set the Content-Type header on your response
// otherwise this middleware will not compress the response body. For ex, in
// your handler you should set w.Header().Set("Content-Type", http.DetectContentType(yourBody))
// or set it manually.
//
// Passing a compression level of 5 is sensible value
func Compress(level int, types ...string) func(next http.Handler) http.Handler {
compressor := NewCompressor(level, types...)
return compressor.Handler
}
// Compressor represents a set of encoding configurations.
type Compressor struct {
level int // The compression level.
// The mapping of encoder names to encoder functions.
encoders map[string]EncoderFunc
// The mapping of pooled encoders to pools.
pooledEncoders map[string]*sync.Pool
// The set of content types allowed to be compressed.
allowedTypes map[string]struct{}
allowedWildcards map[string]struct{}
// The list of encoders in order of decreasing precedence.
encodingPrecedence []string
}
// NewCompressor creates a new Compressor that will handle encoding responses.
//
// The level should be one of the ones defined in the flate package.
// The types are the content types that are allowed to be compressed.
func NewCompressor(level int, types ...string) *Compressor {
// If types are provided, set those as the allowed types. If none are
// provided, use the default list.
allowedTypes := make(map[string]struct{})
allowedWildcards := make(map[string]struct{})
if len(types) > 0 {
for _, t := range types {
if strings.Contains(strings.TrimSuffix(t, "/*"), "*") {
panic(fmt.Sprintf("middleware/compress: Unsupported content-type wildcard pattern '%s'. Only '/*' supported", t))
}
if strings.HasSuffix(t, "/*") {
allowedWildcards[strings.TrimSuffix(t, "/*")] = struct{}{}
} else {
allowedTypes[t] = struct{}{}
}
}
} else {
for _, t := range defaultCompressibleContentTypes {
allowedTypes[t] = struct{}{}
}
}
c := &Compressor{
level: level,
encoders: make(map[string]EncoderFunc),
pooledEncoders: make(map[string]*sync.Pool),
allowedTypes: allowedTypes,
allowedWildcards: allowedWildcards,
}
// Set the default encoders. The precedence order uses the reverse
// ordering that the encoders were added. This means adding new encoders
// will move them to the front of the order.
//
// TODO:
// lzma: Opera.
// sdch: Chrome, Android. Gzip output + dictionary header.
// br: Brotli, see https://github.com/go-chi/chi/pull/326
// HTTP 1.1 "deflate" (RFC 2616) stands for DEFLATE data (RFC 1951)
// wrapped with zlib (RFC 1950). The zlib wrapper uses Adler-32
// checksum compared to CRC-32 used in "gzip" and thus is faster.
//
// But.. some old browsers (MSIE, Safari 5.1) incorrectly expect
// raw DEFLATE data only, without the mentioned zlib wrapper.
// Because of this major confusion, most modern browsers try it
// both ways, first looking for zlib headers.
// Quote by Mark Adler: http://stackoverflow.com/a/9186091/385548
//
// The list of browsers having problems is quite big, see:
// http://zoompf.com/blog/2012/02/lose-the-wait-http-compression
// https://web.archive.org/web/20120321182910/http://www.vervestudios.co/projects/compression-tests/results
//
// That's why we prefer gzip over deflate. It's just more reliable
// and not significantly slower than gzip.
c.SetEncoder("deflate", encoderDeflate)
// TODO: Exception for old MSIE browsers that can't handle non-HTML?
// https://zoompf.com/blog/2012/02/lose-the-wait-http-compression
c.SetEncoder("gzip", encoderGzip)
// NOTE: Not implemented, intentionally:
// case "compress": // LZW. Deprecated.
// case "bzip2": // Too slow on-the-fly.
// case "zopfli": // Too slow on-the-fly.
// case "xz": // Too slow on-the-fly.
return c
}
// SetEncoder can be used to set the implementation of a compression algorithm.
//
// The encoding should be a standardised identifier. See:
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Encoding
//
// For example, add the Brotli algortithm:
//
// import brotli_enc "gopkg.in/kothar/brotli-go.v0/enc"
//
// compressor := middleware.NewCompressor(5, "text/html")
// compressor.SetEncoder("br", func(w http.ResponseWriter, level int) io.Writer {
// params := brotli_enc.NewBrotliParams()
// params.SetQuality(level)
// return brotli_enc.NewBrotliWriter(params, w)
// })
func (c *Compressor) SetEncoder(encoding string, fn EncoderFunc) {
encoding = strings.ToLower(encoding)
if encoding == "" {
panic("the encoding can not be empty")
}
if fn == nil {
panic("attempted to set a nil encoder function")
}
// If we are adding a new encoder that is already registered, we have to
// clear that one out first.
if _, ok := c.pooledEncoders[encoding]; ok {
delete(c.pooledEncoders, encoding)
}
if _, ok := c.encoders[encoding]; ok {
delete(c.encoders, encoding)
}
// If the encoder supports Resetting (IoReseterWriter), then it can be pooled.
encoder := fn(ioutil.Discard, c.level)
if encoder != nil {
if _, ok := encoder.(ioResetterWriter); ok {
pool := &sync.Pool{
New: func() interface{} {
return fn(ioutil.Discard, c.level)
},
}
c.pooledEncoders[encoding] = pool
}
}
// If the encoder is not in the pooledEncoders, add it to the normal encoders.
if _, ok := c.pooledEncoders[encoding]; !ok {
c.encoders[encoding] = fn
}
for i, v := range c.encodingPrecedence {
if v == encoding {
c.encodingPrecedence = append(c.encodingPrecedence[:i], c.encodingPrecedence[i+1:]...)
}
}
c.encodingPrecedence = append([]string{encoding}, c.encodingPrecedence...)
}
// Handler returns a new middleware that will compress the response based on the
// current Compressor.
func (c *Compressor) Handler(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
encoder, encoding, cleanup := c.selectEncoder(r.Header, w)
cw := &compressResponseWriter{
ResponseWriter: w,
w: w,
contentTypes: c.allowedTypes,
contentWildcards: c.allowedWildcards,
encoding: encoding,
compressable: false, // determined in post-handler
}
if encoder != nil {
cw.w = encoder
}
// Re-add the encoder to the pool if applicable.
defer cleanup()
defer cw.Close()
next.ServeHTTP(cw, r)
})
}
// selectEncoder returns the encoder, the name of the encoder, and a closer function.
func (c *Compressor) selectEncoder(h http.Header, w io.Writer) (io.Writer, string, func()) {
header := h.Get("Accept-Encoding")
// Parse the names of all accepted algorithms from the header.
accepted := strings.Split(strings.ToLower(header), ",")
// Find supported encoder by accepted list by precedence
for _, name := range c.encodingPrecedence {
if matchAcceptEncoding(accepted, name) {
if pool, ok := c.pooledEncoders[name]; ok {
encoder := pool.Get().(ioResetterWriter)
cleanup := func() {
pool.Put(encoder)
}
encoder.Reset(w)
return encoder, name, cleanup
}
if fn, ok := c.encoders[name]; ok {
return fn(w, c.level), name, func() {}
}
}
}
// No encoder found to match the accepted encoding
return nil, "", func() {}
}
func matchAcceptEncoding(accepted []string, encoding string) bool {
for _, v := range accepted {
if strings.Contains(v, encoding) {
return true
}
}
return false
}
// An EncoderFunc is a function that wraps the provided io.Writer with a
// streaming compression algorithm and returns it.
//
// In case of failure, the function should return nil.
type EncoderFunc func(w io.Writer, level int) io.Writer
// Interface for types that allow resetting io.Writers.
type ioResetterWriter interface {
io.Writer
Reset(w io.Writer)
}
type compressResponseWriter struct {
http.ResponseWriter
// The streaming encoder writer to be used if there is one. Otherwise,
// this is just the normal writer.
w io.Writer
encoding string
contentTypes map[string]struct{}
contentWildcards map[string]struct{}
wroteHeader bool
compressable bool
}
func (cw *compressResponseWriter) isCompressable() bool {
// Parse the first part of the Content-Type response header.
contentType := cw.Header().Get("Content-Type")
if idx := strings.Index(contentType, ";"); idx >= 0 {
contentType = contentType[0:idx]
}
// Is the content type compressable?
if _, ok := cw.contentTypes[contentType]; ok {
return true
}
if idx := strings.Index(contentType, "/"); idx > 0 {
contentType = contentType[0:idx]
_, ok := cw.contentWildcards[contentType]
return ok
}
return false
}
func (cw *compressResponseWriter) WriteHeader(code int) {
if cw.wroteHeader {
cw.ResponseWriter.WriteHeader(code) // Allow multiple calls to propagate.
return
}
cw.wroteHeader = true
defer cw.ResponseWriter.WriteHeader(code)
// Already compressed data?
if cw.Header().Get("Content-Encoding") != "" {
return
}
if !cw.isCompressable() {
cw.compressable = false
return
}
if cw.encoding != "" {
cw.compressable = true
cw.Header().Set("Content-Encoding", cw.encoding)
cw.Header().Set("Vary", "Accept-Encoding")
// The content-length after compression is unknown
cw.Header().Del("Content-Length")
}
}
func (cw *compressResponseWriter) Write(p []byte) (int, error) {
if !cw.wroteHeader {
cw.WriteHeader(http.StatusOK)
}
return cw.writer().Write(p)
}
func (cw *compressResponseWriter) writer() io.Writer {
if cw.compressable {
return cw.w
} else {
return cw.ResponseWriter
}
}
type compressFlusher interface {
Flush() error
}
func (cw *compressResponseWriter) Flush() {
if f, ok := cw.writer().(http.Flusher); ok {
f.Flush()
}
// If the underlying writer has a compression flush signature,
// call this Flush() method instead
if f, ok := cw.writer().(compressFlusher); ok {
f.Flush()
// Also flush the underlying response writer
if f, ok := cw.ResponseWriter.(http.Flusher); ok {
f.Flush()
}
}
}
func (cw *compressResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
if hj, ok := cw.writer().(http.Hijacker); ok {
return hj.Hijack()
}
return nil, nil, errors.New("chi/middleware: http.Hijacker is unavailable on the writer")
}
func (cw *compressResponseWriter) Push(target string, opts *http.PushOptions) error {
if ps, ok := cw.writer().(http.Pusher); ok {
return ps.Push(target, opts)
}
return errors.New("chi/middleware: http.Pusher is unavailable on the writer")
}
func (cw *compressResponseWriter) Close() error {
if c, ok := cw.writer().(io.WriteCloser); ok {
return c.Close()
}
return errors.New("chi/middleware: io.WriteCloser is unavailable on the writer")
}
func encoderGzip(w io.Writer, level int) io.Writer {
gw, err := gzip.NewWriterLevel(w, level)
if err != nil {
return nil
}
return gw
}
func encoderDeflate(w io.Writer, level int) io.Writer {
dw, err := flate.NewWriter(w, level)
if err != nil {
return nil
}
return dw
}