feat: validate and initialize browser dialer at config build

Agent-Logs-Url: https://github.com/XTLS/Xray-core/sessions/d0035ff5-3633-402f-890e-e68c267a65c1

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

infra/conf/transport_browser_dialer_test.go

@@ -0,0 +1,63 @@
+package conf_test
+
+import (
+	"net"
+	"strings"
+	"testing"
+
+	. "github.com/xtls/xray-core/infra/conf"
+)
+
+const testBrowserDialerPath = "/123e4567-e89b-12d3-a456-426614174000"
+
+func TestStreamConfigBuildRejectsBrowserDialerUnsupportedProtocol(t *testing.T) {
+	network := TransportProtocol("tcp")
+	config := &StreamConfig{
+		Network: &network,
+		SocketSettings: &SocketConfig{
+			BrowserDialer: "127.0.0.1:18080" + testBrowserDialerPath,
+		},
+	}
+
+	_, err := config.Build()
+	if err == nil || !strings.Contains(err.Error(), "sockopt.browserDialer only supports WS or XHTTP") {
+		t.Fatalf("expected unsupported protocol error, got: %v", err)
+	}
+}
+
+func TestStreamConfigBuildRejectsBrowserDialerWithREALITY(t *testing.T) {
+	network := TransportProtocol("splithttp")
+	config := &StreamConfig{
+		Network:  &network,
+		Security: "reality",
+		SocketSettings: &SocketConfig{
+			BrowserDialer: "127.0.0.1:18081" + testBrowserDialerPath,
+		},
+	}
+
+	_, err := config.Build()
+	if err == nil || !strings.Contains(err.Error(), "sockopt.browserDialer does not support REALITY") {
+		t.Fatalf("expected REALITY rejection, got: %v", err)
+	}
+}
+
+func TestStreamConfigBuildFailsOnBrowserDialerAddressConflict(t *testing.T) {
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("failed to prepare occupied listener: %v", err)
+	}
+	defer listener.Close()
+
+	network := TransportProtocol("websocket")
+	config := &StreamConfig{
+		Network: &network,
+		SocketSettings: &SocketConfig{
+			BrowserDialer: listener.Addr().String() + testBrowserDialerPath,
+		},
+	}
+
+	_, err = config.Build()
+	if err == nil || !strings.Contains(err.Error(), "Failed to start Browser Dialer listener") {
+		t.Fatalf("expected address conflict error, got: %v", err)
+	}
+}

infra/conf/transport_internet.go

@@ -21,6 +21,7 @@ import (
 	"github.com/xtls/xray-core/common/platform/filesystem"
 	"github.com/xtls/xray-core/common/serial"
 	"github.com/xtls/xray-core/transport/internet"
+	"github.com/xtls/xray-core/transport/internet/browser_dialer"
 	"github.com/xtls/xray-core/transport/internet/finalmask/fragment"
 	"github.com/xtls/xray-core/transport/internet/finalmask/header/custom"
 	"github.com/xtls/xray-core/transport/internet/finalmask/header/dns"
@@ -1972,6 +1973,14 @@ func (c *StreamConfig) Build() (*internet.StreamConfig, error) {
 		}
 		config.ProtocolName = protocol
 	}
+	if c.SocketSettings != nil && c.SocketSettings.BrowserDialer != "" {
+		if config.ProtocolName != "websocket" && config.ProtocolName != "splithttp" {
+			return nil, errors.New("sockopt.browserDialer only supports WS or XHTTP")
+		}
+		if strings.EqualFold(c.Security, "reality") {
+			return nil, errors.New("sockopt.browserDialer does not support REALITY")
+		}
+	}
 
 	switch strings.ToLower(c.Security) {
 	case "", "none":
@@ -2088,6 +2097,9 @@ func (c *StreamConfig) Build() (*internet.StreamConfig, error) {
 		if err != nil {
 			return nil, errors.New("Failed to build sockopt.").Base(err)
 		}
+		if err := browser_dialer.EnsureDialerWithAddress(ss.BrowserDialer); err != nil {
+			return nil, errors.New("Failed to start Browser Dialer listener.").Base(err)
+		}
 		config.SocketSettings = ss
 	}