Transcode via Brotli

Brotli offers 20% better compression than gzip.

README.md

@@ -11,7 +11,7 @@ Features:
 - HTTPS proxy (encrypted connection between client and proxy)
 - man in the middle support (compress HTTPS traffic)
 - HTTP2 support (over TLS)
-- gzip compression
+- Brotli and gzip compression
 - transcode animated GIFs to static images
 - transcode JPEG images to desired quality using libjpeg
 - transcode PNG and JPEG images to WebP

compy.go

@@ -18,6 +18,7 @@ var (
 	ca    = flag.String("ca", "", "CA path")
 	caKey = flag.String("cakey", "", "CA key path")
 
+	brotli = flag.Int("brotli", -1, "Brotli compression level (0-11, default 6)")
 	jpeg   = flag.Int("jpeg", 50, "jpeg quality (1-100, 0 to disable)")
 	gif    = flag.Bool("gif", true, "transcode gifs into static images")
 	gzip   = flag.Int("gzip", -1, "gzip compression level (0-9, default 6)")
@@ -56,9 +57,9 @@ func main() {
 
 	var ttc proxy.Transcoder
 	if *minify {
-		ttc = &tc.Gzip{tc.NewMinifier(), *gzip, false}
+		ttc = &tc.Zip{tc.NewMinifier(), *brotli, *gzip, false}
 	} else {
-		ttc = &tc.Gzip{&tc.Identity{}, *gzip, true}
+		ttc = &tc.Zip{&tc.Identity{}, *brotli, *gzip, true}
 	}
 
 	p.AddTranscoder("text/css", ttc)

compy_test.go

@@ -15,6 +15,7 @@ import (
 	"github.com/barnacs/compy/proxy"
 	tc "github.com/barnacs/compy/transcoder"
 	"github.com/chai2010/webp"
+	brotlidec "gopkg.in/kothar/brotli-go.v0/dec"
 )
 
 func Test(t *testing.T) {
@@ -34,7 +35,7 @@ func (s *CompyTest) SetUpSuite(c *C) {
 
 	s.proxy = proxy.New()
 	s.proxy.AddTranscoder("image/jpeg", tc.NewJpeg(50))
-	s.proxy.AddTranscoder("text/html", &tc.Gzip{&tc.Identity{}, *gzip, true})
+	s.proxy.AddTranscoder("text/html", &tc.Zip{&tc.Identity{}, *brotli, *gzip, true})
 	go func() {
 		err := s.proxy.Start(*host)
 		if err != nil {
@@ -91,6 +92,23 @@ func (s *CompyTest) TestGzip(c *C) {
 	c.Assert(err, IsNil)
 }
 
+func (s *CompyTest) TestBrotli(c *C) {
+	req, err := http.NewRequest("GET", s.server.URL+"/html", nil)
+	c.Assert(err, IsNil)
+	req.Header.Add("Accept-Encoding", "br, gzip")
+
+	resp, err := s.client.Do(req)
+	c.Assert(err, IsNil)
+	defer resp.Body.Close()
+	c.Assert(resp.StatusCode, Equals, 200)
+	c.Assert(resp.Header.Get("Content-Encoding"), Equals, "br")
+
+	brr := brotlidec.NewBrotliReader(resp.Body)
+	defer brr.Close()
+	_, err = ioutil.ReadAll(brr)
+	c.Assert(err, IsNil)
+}
+
 func (s *CompyTest) TestJpeg(c *C) {
 	req, err := http.NewRequest("GET", s.server.URL+"/image/jpeg", nil)
 	c.Assert(err, IsNil)

transcoder/gzip.go

@@ -1,54 +0,0 @@
-package transcoder
-
-import (
-	"compress/gzip"
-	"github.com/barnacs/compy/proxy"
-	"net/http"
-	"strings"
-)
-
-type Gzip struct {
-	proxy.Transcoder
-	CompressionLevel int
-	SkipGzipped      bool
-}
-
-func (t *Gzip) Transcode(w *proxy.ResponseWriter, r *proxy.ResponseReader, headers http.Header) error {
-	if t.decompress(r) {
-		gzr, err := gzip.NewReader(r.Reader)
-		if err != nil {
-			return err
-		}
-		defer gzr.Close()
-		r.Reader = gzr
-		r.Header().Del("Content-Encoding")
-		w.Header().Del("Content-Encoding")
-	}
-
-	shouldGzip := false
-	for _, v := range strings.Split(headers.Get("Accept-Encoding"), ", ") {
-		if strings.SplitN(v, ";", 2)[0] == "gzip" {
-			shouldGzip = true
-			break
-		}
-	}
-
-	if shouldGzip && compress(r) {
-		gzw, err := gzip.NewWriterLevel(w.Writer, t.CompressionLevel)
-		if err != nil {
-			return err
-		}
-		defer gzw.Close()
-		w.Writer = gzw
-		w.Header().Set("Content-Encoding", "gzip")
-	}
-	return t.Transcoder.Transcode(w, r, headers)
-}
-
-func (t *Gzip) decompress(r *proxy.ResponseReader) bool {
-	return !t.SkipGzipped && r.Header().Get("Content-Encoding") == "gzip"
-}
-
-func compress(r *proxy.ResponseReader) bool {
-	return r.Header().Get("Content-Encoding") == ""
-}

transcoder/zip.go

@@ -0,0 +1,63 @@
+package transcoder
+
+import (
+	"compress/gzip"
+	"github.com/barnacs/compy/proxy"
+	brotlienc "gopkg.in/kothar/brotli-go.v0/enc"
+	"net/http"
+	"strings"
+)
+
+type Zip struct {
+	proxy.Transcoder
+	BrotliCompressionLevel int
+	GzipCompressionLevel   int
+	SkipGzipped            bool
+}
+
+func (t *Zip) Transcode(w *proxy.ResponseWriter, r *proxy.ResponseReader, headers http.Header) error {
+	shouldBrotli := false
+	shouldGzip := false
+	for _, v := range strings.Split(headers.Get("Accept-Encoding"), ", ") {
+		switch strings.SplitN(v, ";", 2)[0] {
+		case "br":
+			shouldBrotli = true
+		case "gzip":
+			shouldGzip = true
+		}
+	}
+
+	// always gunzip if the client supports Brotli
+	if r.Header().Get("Content-Encoding") == "gzip" && (shouldBrotli || !t.SkipGzipped) {
+		gzr, err := gzip.NewReader(r.Reader)
+		if err != nil {
+			return err
+		}
+		defer gzr.Close()
+		r.Reader = gzr
+		r.Header().Del("Content-Encoding")
+		w.Header().Del("Content-Encoding")
+	}
+
+	if shouldBrotli && compress(r) {
+		params := brotlienc.NewBrotliParams()
+		params.SetQuality(t.BrotliCompressionLevel)
+		brw := brotlienc.NewBrotliWriter(params, w.Writer)
+		defer brw.Close()
+		w.Writer = brw
+		w.Header().Set("Content-Encoding", "br")
+	} else if shouldGzip && compress(r) {
+		gzw, err := gzip.NewWriterLevel(w.Writer, t.GzipCompressionLevel)
+		if err != nil {
+			return err
+		}
+		defer gzw.Close()
+		w.Writer = gzw
+		w.Header().Set("Content-Encoding", "gzip")
+	}
+	return t.Transcoder.Transcode(w, r, headers)
+}
+
+func compress(r *proxy.ResponseReader) bool {
+	return r.Header().Get("Content-Encoding") == ""
+}