XHTTP client: Add "fakegrpc-up" mode

infra/conf/transport_internet.go

@@ -306,7 +306,7 @@ func (c *SplitHTTPConfig) Build() (proto.Message, error) {
 	switch c.Mode {
 	case "":
 		c.Mode = "auto"
-	case "auto", "packet-up", "stream-up":
+	case "auto", "packet-up", "stream-up", "fakegrpc-up":
 	default:
 		return nil, errors.New("unsupported mode: " + c.Mode)
 	}

transport/internet/splithttp/browser_client.go

@@ -14,7 +14,7 @@ import (
 // has no fields because everything is global state :O)
 type BrowserDialerClient struct{}
 
-func (c *BrowserDialerClient) OpenUpload(ctx context.Context, baseURL string) io.WriteCloser {
+func (c *BrowserDialerClient) OpenUpload(ctx context.Context, baseURL, mode string) io.WriteCloser {
 	panic("not implemented yet")
 }
 

transport/internet/splithttp/client.go

@@ -26,9 +26,9 @@ type DialerClient interface {
 	// baseURL already contains sessionId
 	OpenDownload(context.Context, string) (io.ReadCloser, net.Addr, net.Addr, error)
 
-	// (ctx, baseURL) -> uploadWriter
+	// (ctx, baseURL, mode) -> uploadWriter
 	// baseURL already contains sessionId
-	OpenUpload(context.Context, string) io.WriteCloser
+	OpenUpload(context.Context, string, string) io.WriteCloser
 }
 
 // implements splithttp.DialerClient in terms of direct network connections
@@ -42,10 +42,13 @@ type DefaultDialerClient struct {
 	dialUploadConn func(ctxInner context.Context) (net.Conn, error)
 }
 
-func (c *DefaultDialerClient) OpenUpload(ctx context.Context, baseURL string) io.WriteCloser {
+func (c *DefaultDialerClient) OpenUpload(ctx context.Context, baseURL, mode string) io.WriteCloser {
 	reader, writer := io.Pipe()
 	req, _ := http.NewRequestWithContext(ctx, "POST", baseURL, reader)
 	req.Header = c.transportConfig.GetRequestHeader()
+	if mode == "fakegrpc-up" {
+		req.Header.Add("Content-Type", "application/grpc")
+	}
 	go c.client.Do(req)
 	return writer
 }

transport/internet/splithttp/dialer.go

@@ -312,11 +312,15 @@ func Dial(ctx context.Context, dest net.Destination, streamSettings *internet.Me
 	}
 
 	mode := transportConfiguration.Mode
-	if mode == "auto" && realityConfig != nil {
-		mode = "stream-up"
+	if mode == "auto" {
+		if tlsConfig == nil && realityConfig == nil {
+			mode = "packet-up"
+		} else {
+			mode = "fakegrpc-up"
+		}
 	}
-	if mode == "stream-up" {
-		conn.writer = httpClient.OpenUpload(ctx, requestURL.String())
+	if mode != "packet-up" {
+		conn.writer = httpClient.OpenUpload(ctx, requestURL.String(), mode)
 		return stat.Connection(&conn), nil
 	}