net/http: don't send Accept-Encoding on HEAD requests

Works around a bug in nginx: http://trac.nginx.org/nginx/ticket/358

Fixes #5522

R=iant
CC=gobot, golang-dev
https://golang.org/cl/9627043

diff --git a/src/pkg/net/http/transport.go b/src/pkg/net/http/transport.go
index 4cd0533ffc26c3fdeeb30a57810b8e0938550495..41ac7dea148a39cea6f922ad8483cc68bf361bcd 100644 (file)
--- a/src/pkg/net/http/transport.go
+++ b/src/pkg/net/http/transport.go
@@ -831,10 +831,15 @@ func (pc *persistConn) roundTrip(req *transportRequest) (resp *Response, err err
        // uncompress the gzip stream if we were the layer that
        // requested it.
        requestedGzip := false
-       if !pc.t.DisableCompression && req.Header.Get("Accept-Encoding") == "" {
+       if !pc.t.DisableCompression && req.Header.Get("Accept-Encoding") == "" && req.Method != "HEAD" {
                // Request gzip only, not deflate. Deflate is ambiguous and
                // not as universally supported anyway.
                // See: http://www.gzip.org/zlib/zlib_faq.html#faq38
+               //
+               // Note that we don't request this for HEAD requests,
+               // due to a bug in nginx:
+               //   http://trac.nginx.org/nginx/ticket/358
+               //   http://golang.org/issue/5522
                requestedGzip = true
                req.extraHeaders().Set("Accept-Encoding", "gzip")
        }

diff --git a/src/pkg/net/http/transport_test.go b/src/pkg/net/http/transport_test.go
index 9f64a6e4b5fd35e361c789dad332f80933b414b3..9f5181e49cbb1440ee9bea05c2de901a3cadd719 100644 (file)
--- a/src/pkg/net/http/transport_test.go
+++ b/src/pkg/net/http/transport_test.go
@@ -585,13 +585,16 @@ func TestTransportGzip(t *testing.T) {
        const testString = "The test string aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
        const nRandBytes = 1024 * 1024
        ts := httptest.NewServer(HandlerFunc(func(rw ResponseWriter, req *Request) {
+               if req.Method == "HEAD" {
+                       if g := req.Header.Get("Accept-Encoding"); g != "" {
+                               t.Errorf("HEAD request sent with Accept-Encoding of %q; want none", g)
+                       }
+                       return
+               }
                if g, e := req.Header.Get("Accept-Encoding"), "gzip"; g != e {
                        t.Errorf("Accept-Encoding = %q, want %q", g, e)
                }
                rw.Header().Set("Content-Encoding", "gzip")
-               if req.Method == "HEAD" {
-                       return
-               }
 
                var w io.Writer = rw
                var buf bytes.Buffer