redo CL 5302057 / dac58d9c9e4a

««« original CL description
http: remove Connection header in ReverseProxy

Fixes #2342

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/5302057
»»»

R=bradfitz, dsymonds
CC=golang-dev
https://golang.org/cl/5296055

1 files changed, 19 insertions, 6 deletions

diff --git a/src/pkg/http/reverseproxy.go b/src/pkg/http/reverseproxy.go
index 3f8bfdc80c..3a63db009f 100644
--- a/src/pkg/http/reverseproxy.go
+++ b/src/pkg/http/reverseproxy.go
@@ -69,6 +69,14 @@ func NewSingleHostReverseProxy(target *url.URL) *ReverseProxy {
 	return &ReverseProxy{Director: director}
 }
 
+func copyHeader(dst, src Header) {
+	for k, vv := range src {
+		for _, v := range vv {
+			dst.Add(k, v)
+		}
+	}
+}
+
 func (p *ReverseProxy) ServeHTTP(rw ResponseWriter, req *Request) {
 	transport := p.Transport
 	if transport == nil {
@@ -84,6 +92,16 @@ func (p *ReverseProxy) ServeHTTP(rw ResponseWriter, req *Request) {
 	outreq.ProtoMinor = 1
 	outreq.Close = false
 
+	// Remove the connection header to the backend.  We want a
+	// persistent connection, regardless of what the client sent
+	// to us.  This is modifying the same underlying map from req
+	// (shallow copied above) so we only copy it if necessary.
+	if outreq.Header.Get("Connection") != "" {
+		outreq.Header = make(Header)
+		copyHeader(outreq.Header, req.Header)
+		outreq.Header.Del("Connection")
+	}
+
 	if clientIp, _, err := net.SplitHostPort(req.RemoteAddr); err == nil {
 		outreq.Header.Set("X-Forwarded-For", clientIp)
 	}
@@ -95,12 +113,7 @@ func (p *ReverseProxy) ServeHTTP(rw ResponseWriter, req *Request) {
 		return
 	}
 
-	hdr := rw.Header()
-	for k, vv := range res.Header {
-		for _, v := range vv {
-			hdr.Add(k, v)
-		}
-	}
+	copyHeader(rw.Header(), res.Header)
 
 	rw.WriteHeader(res.StatusCode)