feat: Add Content-Encoding support for brotli, gzip, and deflate (#24)

feat: Add Content-Encoding support for brotli, gzip, and deflate
Co-authored-by: Jon Lundy <jon@xuu.cc>
Reviewed-on: https://git.mills.io/prologic/msgbus/pulls/24
Co-authored-by: xuu <xuu@noreply@mills.io>
Co-committed-by: xuu <xuu@noreply@mills.io>

go.mod

@@ -17,6 +17,7 @@ require (
 )
 
 require (
+	github.com/andybalholm/brotli v1.0.4 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.1.2 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect

go.sum

@@ -57,6 +57,8 @@ github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuy
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/alecthomas/units v0.0.0-20190717042225-c3de453c63f4/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d/go.mod h1:rBZYJk541a8SKzHPHnH3zbiI+7dagKZ0cgpgrD7Fyho=
+github.com/andybalholm/brotli v1.0.4 h1:V7DdXeJtZscaqfNuAdSRuRFzuiKlHSC/Zh3zl9qY3JY=
+github.com/andybalholm/brotli v1.0.4/go.mod h1:fO7iG3H7G2nSZ7m0zPUDn85XEX2GTukHGRSepvi9Eig=
 github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
 github.com/armon/circbuf v0.0.0-20150827004946-bbbad097214e/go.mod h1:3U/XgcO3hCbHZ8TKRvWD2dDTCfh9M9ya+I9JpbB7O8o=
 github.com/armon/go-metrics v0.0.0-20180917152333-f0300d1749da/go.mod h1:Q73ZrmVTwzkszR9V5SSuryQ31EELlFMUz1kKyl939pY=

msgbus.go

@@ -1,8 +1,11 @@
 package msgbus
 
 import (
+	"compress/flate"
+	"compress/gzip"
 	"encoding/json"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"strconv"
@@ -10,6 +13,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/andybalholm/brotli"
 	log "github.com/sirupsen/logrus"
 
 	"github.com/gorilla/websocket"
@@ -477,6 +481,7 @@ func (mb *MessageBus) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}()
 
 	w.Header().Set("Access-Control-Allow-Origin", "*")
+	w.Header().Set("Accept-Encoding", "br, gzip, deflate")
 
 	if r.Method == "GET" && (r.URL.Path == "/" || r.URL.Path == "") {
 		// XXX: guard with a mutex?
@@ -500,13 +505,40 @@ func (mb *MessageBus) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	switch r.Method {
 	case "POST", "PUT":
+		defer r.Body.Close()
+
 		if r.ContentLength > int64(mb.maxPayloadSize) {
 			msg := "payload exceeds max-payload-size"
 			http.Error(w, msg, http.StatusRequestEntityTooLarge)
 			return
 		}
 
-		body, err := ioutil.ReadAll(r.Body)
+		var rd io.Reader = r.Body
+		ce := r.Header.Get("Content-Encoding")
+		switch ce {
+		case "":
+		case "br":
+			rd = brotli.NewReader(rd)
+		case "gzip":
+			gz, err := gzip.NewReader(rd)
+			if err != nil {
+				msg := fmt.Sprintf("error reading payload: %s", err)
+				http.Error(w, msg, http.StatusBadRequest)
+				return
+			}
+			defer gz.Close()
+			rd = gz
+		case "deflate":
+			fl := flate.NewReader(rd)
+			defer fl.Close()
+			rd = fl
+		default:
+			msg := fmt.Sprintf("error reading payload: not acceptable: %v", ce)
+			http.Error(w, msg, http.StatusNotAcceptable)
+			return
+		}
+
+		body, err := ioutil.ReadAll(rd)
 		if err != nil {
 			msg := fmt.Sprintf("error reading payload: %s", err)
 			http.Error(w, msg, http.StatusBadRequest)
@@ -517,7 +549,6 @@ func (mb *MessageBus) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			http.Error(w, msg, http.StatusRequestEntityTooLarge)
 			return
 		}
-
 		mb.Put(mb.NewMessage(t, body))
 
 		w.WriteHeader(http.StatusAccepted)