TUN-528: Move cloudflared into a separate repo

vendor/github.com/mholt/caddy/caddyhttp/gzip/gzip.go

@@ -0,0 +1,143 @@
+// Copyright 2015 Light Code Labs, LLC
+//
+// 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 provides a middleware layer that performs
+// gzip compression on the response.
+package gzip
+
+import (
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/mholt/caddy"
+	"github.com/mholt/caddy/caddyhttp/httpserver"
+)
+
+func init() {
+	caddy.RegisterPlugin("gzip", caddy.Plugin{
+		ServerType: "http",
+		Action:     setup,
+	})
+
+	initWriterPool()
+}
+
+// Gzip is a middleware type which gzips HTTP responses. It is
+// imperative that any handler which writes to a gzipped response
+// specifies the Content-Type, otherwise some clients will assume
+// application/x-gzip and try to download a file.
+type Gzip struct {
+	Next    httpserver.Handler
+	Configs []Config
+}
+
+// Config holds the configuration for Gzip middleware
+type Config struct {
+	RequestFilters  []RequestFilter
+	ResponseFilters []ResponseFilter
+	Level           int // Compression level
+}
+
+// ServeHTTP serves a gzipped response if the client supports it.
+func (g Gzip) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
+	if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
+		return g.Next.ServeHTTP(w, r)
+	}
+outer:
+	for _, c := range g.Configs {
+
+		// Check request filters to determine if gzipping is permitted for this request
+		for _, filter := range c.RequestFilters {
+			if !filter.ShouldCompress(r) {
+				continue outer
+			}
+		}
+
+		// gzipWriter modifies underlying writer at init,
+		// use a discard writer instead to leave ResponseWriter in
+		// original form.
+		gzipWriter := getWriter(c.Level)
+		defer putWriter(c.Level, gzipWriter)
+		gz := &gzipResponseWriter{
+			Writer:                gzipWriter,
+			ResponseWriterWrapper: &httpserver.ResponseWriterWrapper{ResponseWriter: w},
+		}
+
+		var rw http.ResponseWriter
+		// if no response filter is used
+		if len(c.ResponseFilters) == 0 {
+			// replace discard writer with ResponseWriter
+			gzipWriter.Reset(w)
+			rw = gz
+		} else {
+			// wrap gzip writer with ResponseFilterWriter
+			rw = NewResponseFilterWriter(c.ResponseFilters, gz)
+		}
+
+		// Any response in forward middleware will now be compressed
+		status, err := g.Next.ServeHTTP(rw, r)
+
+		// If there was an error that remained unhandled, we need
+		// to send something back before gzipWriter gets closed at
+		// the return of this method!
+		if status >= 400 {
+			httpserver.DefaultErrorFunc(w, r, status)
+			return 0, err
+		}
+		return status, err
+	}
+
+	// no matching filter
+	return g.Next.ServeHTTP(w, r)
+}
+
+// gzipResponeWriter wraps the underlying Write method
+// with a gzip.Writer to compress the output.
+type gzipResponseWriter struct {
+	io.Writer
+	*httpserver.ResponseWriterWrapper
+	statusCodeWritten bool
+}
+
+// WriteHeader wraps the underlying WriteHeader method to prevent
+// problems with conflicting headers from proxied backends. For
+// example, a backend system that calculates Content-Length would
+// be wrong because it doesn't know it's being gzipped.
+func (w *gzipResponseWriter) WriteHeader(code int) {
+	w.Header().Del("Content-Length")
+	w.Header().Set("Content-Encoding", "gzip")
+	w.Header().Add("Vary", "Accept-Encoding")
+	originalEtag := w.Header().Get("ETag")
+	if originalEtag != "" && !strings.HasPrefix(originalEtag, "W/") {
+		w.Header().Set("ETag", "W/"+originalEtag)
+	}
+	w.ResponseWriterWrapper.WriteHeader(code)
+	w.statusCodeWritten = true
+}
+
+// Write wraps the underlying Write method to do compression.
+func (w *gzipResponseWriter) Write(b []byte) (int, error) {
+	if w.Header().Get("Content-Type") == "" {
+		w.Header().Set("Content-Type", http.DetectContentType(b))
+	}
+	if !w.statusCodeWritten {
+		w.WriteHeader(http.StatusOK)
+	}
+	n, err := w.Writer.Write(b)
+	return n, err
+}
+
+// Interface guards
+var _ httpserver.HTTPInterfaces = (*gzipResponseWriter)(nil)