Allow clients to set Host in headers

connect_ext_test.go

@@ -521,6 +521,33 @@ func TestHeaderBasic(t *testing.T) {
  assert.Equal(t, response.Header().Get(key), hval)
 }
 
+func TestHeaderHost(t *testing.T) {
+ t.Parallel()
+ const (
+ key = "Host"
+ cval = "buf.build"
+ )
+
+ pingServer := &pluggablePingServer{
+ ping: func(_ context.Context, request *connect.Request[pingv1.PingRequest]) (*connect.Response[pingv1.PingResponse], error) {
+ assert.Equal(t, request.Header().Get(key), cval)
+ response := connect.NewResponse(&pingv1.PingResponse{})
+ return response, nil
+ },
+ }
+ mux := http.NewServeMux()
+ mux.Handle(pingv1connect.NewPingServiceHandler(pingServer))
+ server := httptest.NewServer(mux)
+ defer server.Close()
+
+ client := pingv1connect.NewPingServiceClient(server.Client(), server.URL)
+ request := connect.NewRequest(&pingv1.PingRequest{})
+ request.Header().Set(key, cval)
+ response, err := client.Ping(context.Background(), request)
+ assert.Nil(t, err)
+ assert.Equal(t, response.Header().Get(key), "")
+}
+
 func TestTimeoutParsing(t *testing.T) {
  t.Parallel()
  const timeout = 10 * time.Minute

handler.go

@@ -176,7 +176,7 @@ func NewBidiStreamHandler[Req, Res any](
 
 // ServeHTTP implements [http.Handler].
 func (h *Handler) ServeHTTP(responseWriter http.ResponseWriter, request *http.Request) {
- // We don't need to defer functions  to close the request body or read to
+ // We don't need to defer functions to close the request body or read to
  // EOF: the stream we construct later on already does that, and we only
  // return early when dealing with misbehaving clients. In those cases, it's
  // okay if we can't re-use the connection.

protocol_connect.go

@@ -164,6 +164,9 @@ func (h *connectHandler) NewConn(
  contentEncoding = getHeaderCanonical(request.Header, connectStreamingHeaderCompression)
  acceptEncoding = getHeaderCanonical(request.Header, connectStreamingHeaderAcceptCompression)
  }
+ if host := request.Host; len(host) > 0 {
+ request.Header["Host"] = []string{host}
+ }
  requestCompression, responseCompression, failed := negotiateCompression(
  h.CompressionPools,
  contentEncoding,
@@ -367,6 +370,9 @@ func (c *connectClient) NewConn(
  }
  }
  duplexCall := newDuplexHTTPCall(ctx, c.HTTPClient, c.URL, spec, header)
+ if hosts := header["Host"]; len(hosts) > 0 {
+ duplexCall.request.Host = hosts[0]
+ }
  var conn streamingClientConn
  if spec.StreamType == StreamTypeUnary {
  unaryConn := &connectUnaryClientConn{