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126 lines
3.5 KiB
Go
126 lines
3.5 KiB
Go
// Package gzip provides a middleware layer that performs
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// gzip compression on the response.
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package gzip
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import (
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"io"
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"net/http"
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"strings"
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"github.com/mholt/caddy"
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"github.com/mholt/caddy/caddyhttp/httpserver"
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)
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func init() {
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caddy.RegisterPlugin("gzip", caddy.Plugin{
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ServerType: "http",
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Action: setup,
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})
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initWriterPool()
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}
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// Gzip is a middleware type which gzips HTTP responses. It is
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// imperative that any handler which writes to a gzipped response
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// specifies the Content-Type, otherwise some clients will assume
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// application/x-gzip and try to download a file.
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type Gzip struct {
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Next httpserver.Handler
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Configs []Config
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}
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// Config holds the configuration for Gzip middleware
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type Config struct {
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RequestFilters []RequestFilter
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ResponseFilters []ResponseFilter
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Level int // Compression level
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}
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// ServeHTTP serves a gzipped response if the client supports it.
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func (g Gzip) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
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if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
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return g.Next.ServeHTTP(w, r)
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}
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outer:
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for _, c := range g.Configs {
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// Check request filters to determine if gzipping is permitted for this request
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for _, filter := range c.RequestFilters {
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if !filter.ShouldCompress(r) {
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continue outer
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}
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}
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// gzipWriter modifies underlying writer at init,
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// use a discard writer instead to leave ResponseWriter in
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// original form.
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gzipWriter := getWriter(c.Level)
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defer putWriter(c.Level, gzipWriter)
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gz := &gzipResponseWriter{
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Writer: gzipWriter,
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ResponseWriterWrapper: &httpserver.ResponseWriterWrapper{ResponseWriter: w},
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}
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var rw http.ResponseWriter
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// if no response filter is used
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if len(c.ResponseFilters) == 0 {
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// replace discard writer with ResponseWriter
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gzipWriter.Reset(w)
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rw = gz
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} else {
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// wrap gzip writer with ResponseFilterWriter
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rw = NewResponseFilterWriter(c.ResponseFilters, gz)
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}
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// Any response in forward middleware will now be compressed
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status, err := g.Next.ServeHTTP(rw, r)
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// If there was an error that remained unhandled, we need
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// to send something back before gzipWriter gets closed at
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// the return of this method!
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if status >= 400 {
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httpserver.DefaultErrorFunc(w, r, status)
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return 0, err
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}
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return status, err
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}
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// no matching filter
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return g.Next.ServeHTTP(w, r)
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}
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// gzipResponeWriter wraps the underlying Write method
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// with a gzip.Writer to compress the output.
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type gzipResponseWriter struct {
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io.Writer
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*httpserver.ResponseWriterWrapper
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statusCodeWritten bool
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}
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// WriteHeader wraps the underlying WriteHeader method to prevent
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// problems with conflicting headers from proxied backends. For
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// example, a backend system that calculates Content-Length would
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// be wrong because it doesn't know it's being gzipped.
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func (w *gzipResponseWriter) WriteHeader(code int) {
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w.Header().Del("Content-Length")
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w.Header().Set("Content-Encoding", "gzip")
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w.Header().Add("Vary", "Accept-Encoding")
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w.ResponseWriterWrapper.WriteHeader(code)
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w.statusCodeWritten = true
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}
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// Write wraps the underlying Write method to do compression.
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func (w *gzipResponseWriter) Write(b []byte) (int, error) {
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if w.Header().Get("Content-Type") == "" {
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w.Header().Set("Content-Type", http.DetectContentType(b))
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}
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if !w.statusCodeWritten {
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w.WriteHeader(http.StatusOK)
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}
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n, err := w.Writer.Write(b)
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return n, err
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}
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// Interface guards
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var _ httpserver.HTTPInterfaces = (*gzipResponseWriter)(nil)
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