make :authority propagate to MD

server.go

@@ -460,6 +460,10 @@ func (s *Server) processUnaryRPC(t transport.ServerTransport, stream *transport.
 			}
 		}()
 	}
+	if s.opts.cp != nil {
+		// NOTE: this needs to be ahead of all handling, https://github.com/grpc/grpc-go/issues/686.
+		stream.SetSendCompress(s.opts.cp.Type())
+	}
 	p := &parser{r: stream}
 	for {
 		pf, req, err := p.recvMsg()
@@ -545,9 +549,6 @@ func (s *Server) processUnaryRPC(t transport.ServerTransport, stream *transport.
 			Last:  true,
 			Delay: false,
 		}
-		if s.opts.cp != nil {
-			stream.SetSendCompress(s.opts.cp.Type())
-		}
 		if err := s.sendResponse(t, stream, reply, s.opts.cp, opts); err != nil {
 			switch err := err.(type) {
 			case transport.ConnectionError:

test/end2end_test.go

@@ -130,6 +130,9 @@ func newPayload(t testpb.PayloadType, size int32) (*testpb.Payload, error) {
 func (s *testServer) UnaryCall(ctx context.Context, in *testpb.SimpleRequest) (*testpb.SimpleResponse, error) {
 	md, ok := metadata.FromContext(ctx)
 	if ok {
+		if _, exists := md[":authority"]; !exists {
+			return nil, grpc.Errorf(codes.DataLoss, "expected an :authority metadata: %v", md)
+		}
 		if err := grpc.SendHeader(ctx, md); err != nil {
 			return nil, fmt.Errorf("grpc.SendHeader(%v, %v) = %v, want %v", ctx, md, err, nil)
 		}
@@ -167,15 +170,19 @@ func (s *testServer) UnaryCall(ctx context.Context, in *testpb.SimpleRequest) (*
 	if err != nil {
 		return nil, err
 	}
+
 	return &testpb.SimpleResponse{
 		Payload: payload,
 	}, nil
 }
 
 func (s *testServer) StreamingOutputCall(args *testpb.StreamingOutputCallRequest, stream testpb.TestService_StreamingOutputCallServer) error {
 	if md, ok := metadata.FromContext(stream.Context()); ok {
-		// For testing purpose, returns an error if there is attached metadata.
-		if len(md) > 0 {
+		if _, exists := md[":authority"]; !exists {
+			return grpc.Errorf(codes.DataLoss, "expected an :authority metadata: %v", md)
+		}
+		// For testing purpose, returns an error if there is attached metadata except for authority.
+		if len(md) > 1 {
 			return grpc.Errorf(codes.DataLoss, "got extra metadata")
 		}
 	}
@@ -1678,7 +1685,8 @@ func testCompressOK(t *testing.T, e env) {
 		ResponseSize: proto.Int32(respSize),
 		Payload:      payload,
 	}
-	if _, err := tc.UnaryCall(context.Background(), req); err != nil {
+	ctx := metadata.NewContext(context.Background(), metadata.Pairs("something", "something"))
+	if _, err := tc.UnaryCall(ctx, req); err != nil {
 		t.Fatalf("TestService/UnaryCall(_, _) = _, %v, want _, <nil>", err)
 	}
 	// Streaming RPC

transport/handler_server.go

@@ -92,9 +92,12 @@ func NewServerHandlerTransport(w http.ResponseWriter, r *http.Request) (ServerTr
 	}
 
 	var metakv []string
+	if r.Host != "" {
+		metakv = append(metakv, ":authority", r.Host)
+	}
 	for k, vv := range r.Header {
 		k = strings.ToLower(k)
-		if isReservedHeader(k) {
+		if isReservedHeader(k) && !isWhitelistedPseudoHeader(k){
 			continue
 		}
 		for _, v := range vv {
@@ -108,7 +111,6 @@ func NewServerHandlerTransport(w http.ResponseWriter, r *http.Request) (ServerTr
 				}
 			}
 			metakv = append(metakv, k, v)
-
 		}
 	}
 	st.headerMD = metadata.Pairs(metakv...)
@@ -196,6 +198,10 @@ func (ht *serverHandlerTransport) WriteStatus(s *Stream, statusCode codes.Code,
 		}
 		if md := s.Trailer(); len(md) > 0 {
 			for k, vv := range md {
+				// Clients don't tolerate reading restricted headers after some non restricted ones were sent.
+				if isReservedHeader(k) {
+					continue
+				}
 				for _, v := range vv {
 					// http2 ResponseWriter mechanism to
 					// send undeclared Trailers after the
@@ -249,6 +255,10 @@ func (ht *serverHandlerTransport) WriteHeader(s *Stream, md metadata.MD) error {
 		ht.writeCommonHeaders(s)
 		h := ht.rw.Header()
 		for k, vv := range md {
+			// Clients don't tolerate reading restricted headers after some non restricted ones were sent.
+			if isReservedHeader(k) {
+				continue
+			}
 			for _, v := range vv {
 				h.Add(k, v)
 			}

transport/http2_client.go

@@ -341,6 +341,10 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (_ *Strea
 	if md, ok := metadata.FromContext(ctx); ok {
 		hasMD = true
 		for k, v := range md {
+			// HTTP doesn't allow you to set pseudoheaders after non pseudoheaders were set.
+			if isReservedHeader(k) {
+				continue
+			}
 			for _, entry := range v {
 				t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: entry})
 			}

transport/http2_server.go

@@ -460,6 +460,10 @@ func (t *http2Server) WriteHeader(s *Stream, md metadata.MD) error {
 		t.hEnc.WriteField(hpack.HeaderField{Name: "grpc-encoding", Value: s.sendCompress})
 	}
 	for k, v := range md {
+		if isReservedHeader(k) {
+			// Clients don't tolerate reading restricted headers after some non restricted ones were sent.
+			continue
+		}
 		for _, entry := range v {
 			t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: entry})
 		}
@@ -502,6 +506,10 @@ func (t *http2Server) WriteStatus(s *Stream, statusCode codes.Code, statusDesc s
 	t.hEnc.WriteField(hpack.HeaderField{Name: "grpc-message", Value: statusDesc})
 	// Attach the trailer metadata.
 	for k, v := range s.trailer {
+		// Clients don't tolerate reading restricted headers after some non restricted ones were sent.
+		if isReservedHeader(k) {
+			continue
+		}
 		for _, entry := range v {
 			t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: entry})
 		}

transport/http_util.go

@@ -127,6 +127,17 @@ func isReservedHeader(hdr string) bool {
 	}
 }
 
+// isWhitelistedPseudoHeader checks whether hdr belongs to HTTP2 pseudoheaders
+// that should be propagated into metadata visible to users.
+func isWhitelistedPseudoHeader(hdr string) bool {
+	switch hdr {
+	case ":authority":
+		return true
+	default:
+		return false
+	}
+}
+
 func (d *decodeState) setErr(err error) {
 	if d.err == nil {
 		d.err = err
@@ -162,7 +173,7 @@ func (d *decodeState) processHeaderField(f hpack.HeaderField) {
 	case ":path":
 		d.method = f.Value
 	default:
-		if !isReservedHeader(f.Name) {
+		if !isReservedHeader(f.Name) || isWhitelistedPseudoHeader(f.Name) {
 			if f.Name == "user-agent" {
 				i := strings.LastIndex(f.Value, " ")
 				if i == -1 {