fix: allow same-address browser dialer port reuse across outbounds

Agent-Logs-Url: https://github.com/XTLS/Xray-core/sessions/b21c3fc4-8476-4107-975a-9d921d55ffea

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

transport/internet/browser_dialer/dialer.go

@@ -173,6 +173,10 @@ func getDialerByAddress(addr string) (*dialerInstance, error) {
 	if !ok {
 		return nil, errors.New("invalid sockopt.browserDialer: ", addr)
 	}
+	_, port, err := net.SplitHostPort(listenAddr)
+	if err != nil {
+		return nil, errors.New("invalid sockopt.browserDialer: ", addr)
+	}
 
 	key := listenAddr + path
 
@@ -191,6 +195,12 @@ func getDialerByAddress(addr string) (*dialerInstance, error) {
 
 	server, found := dialerServers[listenAddr]
 	if !found {
+		for existingAddr := range dialerServers {
+			_, existingPort, splitErr := net.SplitHostPort(existingAddr)
+			if splitErr == nil && existingPort == port {
+				return nil, errors.New("sockopt.browserDialer cannot use the same port with a different listen address: ", existingAddr, " and ", listenAddr)
+			}
+		}
 		newServer, serverErr := newDialerServer(listenAddr)
 		if serverErr != nil {
 			return nil, serverErr

transport/internet/browser_dialer/dialer_test.go

@@ -1,6 +1,10 @@
 package browser_dialer
 
-import "testing"
+import (
+	"net"
+	"strconv"
+	"testing"
+)
 
 func TestParseBrowserDialerAddressRequireUUIDPath(t *testing.T) {
 	valid := "127.0.0.1:8080/123e4567-e89b-12d3-a456-426614174000"
@@ -20,3 +24,39 @@ func TestParseBrowserDialerAddressRequireUUIDPath(t *testing.T) {
 		}
 	}
 }
+
+func TestEnsureDialerWithAddressReusesSameListenAddress(t *testing.T) {
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	port := listener.Addr().(*net.TCPAddr).Port
+	listener.Close()
+
+	addr1 := net.JoinHostPort("127.0.0.1", strconv.Itoa(port)) + "/123e4567-e89b-12d3-a456-426614174000"
+	addr2 := net.JoinHostPort("127.0.0.1", strconv.Itoa(port)) + "/123e4567-e89b-12d3-a456-426614174001"
+	if err := EnsureDialerWithAddress(addr1); err != nil {
+		t.Fatalf("failed to ensure first browser dialer: %v", err)
+	}
+	if err := EnsureDialerWithAddress(addr2); err != nil {
+		t.Fatalf("failed to reuse browser dialer listener on same address: %v", err)
+	}
+}
+
+func TestEnsureDialerWithAddressRejectsSamePortDifferentAddress(t *testing.T) {
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	port := listener.Addr().(*net.TCPAddr).Port
+	listener.Close()
+
+	addr1 := net.JoinHostPort("127.0.0.1", strconv.Itoa(port)) + "/123e4567-e89b-12d3-a456-426614174010"
+	addr2 := net.JoinHostPort("127.0.0.2", strconv.Itoa(port)) + "/123e4567-e89b-12d3-a456-426614174011"
+	if err := EnsureDialerWithAddress(addr1); err != nil {
+		t.Fatalf("failed to ensure first browser dialer: %v", err)
+	}
+	if err := EnsureDialerWithAddress(addr2); err == nil {
+		t.Fatal("expected error for same port with different listen address")
+	}
+}