fix: add retry mechanism for tunnel service bind conflicts

When tunnel services encounter 'address already in use' errors during
creation/update, automatically cleanup and retry once instead of failing
immediately. This handles race conditions during rapid tunnel reconfiguration.

Entire-Checkpoint: 39e6fb9de836

go-backend/internal/http/handler/control_plane_test.go

@@ -273,6 +273,75 @@ func TestIsCannotAssignRequestedAddressError(t *testing.T) {
 	}
 }
 
+func TestRetryTunnelServiceAddWithCleanupRetriesOnAddressInUse(t *testing.T) {
+	addCalls := 0
+	cleanupCalls := 0
+	err := retryTunnelServiceAddWithCleanup(
+		func() error {
+			addCalls++
+			if addCalls == 1 {
+				return errors.New("listen tcp 10.0.0.1:32000: bind: address already in use")
+			}
+			return nil
+		},
+		func() error {
+			cleanupCalls++
+			return nil
+		},
+		0,
+	)
+	if err != nil {
+		t.Fatalf("expected retry to succeed, got %v", err)
+	}
+	if addCalls != 2 {
+		t.Fatalf("expected 2 add attempts, got %d", addCalls)
+	}
+	if cleanupCalls != 1 {
+		t.Fatalf("expected 1 cleanup attempt, got %d", cleanupCalls)
+	}
+}
+
+func TestRetryTunnelServiceAddWithCleanupSkipsCleanupOnNonBindError(t *testing.T) {
+	addCalls := 0
+	cleanupCalls := 0
+	err := retryTunnelServiceAddWithCleanup(
+		func() error {
+			addCalls++
+			return errors.New("network timeout")
+		},
+		func() error {
+			cleanupCalls++
+			return nil
+		},
+		0,
+	)
+	if err == nil {
+		t.Fatalf("expected hard error")
+	}
+	if addCalls != 1 {
+		t.Fatalf("expected 1 add attempt, got %d", addCalls)
+	}
+	if cleanupCalls != 0 {
+		t.Fatalf("expected 0 cleanup attempts, got %d", cleanupCalls)
+	}
+}
+
+func TestRetryTunnelServiceAddWithCleanupReturnsCleanupError(t *testing.T) {
+	cleanupErr := errors.New("delete failed")
+	err := retryTunnelServiceAddWithCleanup(
+		func() error {
+			return errors.New("listen tcp 10.0.0.1:32000: bind: address already in use")
+		},
+		func() error {
+			return cleanupErr
+		},
+		0,
+	)
+	if !errors.Is(err, cleanupErr) {
+		t.Fatalf("expected cleanup error %v, got %v", cleanupErr, err)
+	}
+}
+
 func TestBuildForwardServiceConfigs_UsesBindIPForListen(t *testing.T) {
 	forward := &forwardRecord{RemoteAddr: "1.2.3.4:80", Strategy: "fifo", TunnelID: 7}
 	node := &nodeRecord{TCPListenAddr: "[::]", UDPListenAddr: "[::]"}

go-backend/internal/http/handler/dual_stack_test.go

@@ -43,6 +43,19 @@ func TestBuildTunnelChainServiceConfig_UsesConnectIPForListen(t *testing.T) {
 	}
 }
 
+func TestBuildTunnelChainServiceConfig_FallsBackToNodeListenAddr(t *testing.T) {
+	node := &nodeRecord{TCPListenAddr: "10.8.0.5"}
+	chain := tunnelRuntimeNode{Protocol: "tls", Port: 21002}
+	services := buildTunnelChainServiceConfig(99, chain, node)
+	if len(services) != 1 {
+		t.Fatalf("expected 1 service, got %d", len(services))
+	}
+	addr, _ := services[0]["addr"].(string)
+	if addr != "10.8.0.5:21002" {
+		t.Fatalf("expected node listen addr 10.8.0.5:21002, got %q", addr)
+	}
+}
+
 func TestBuildTunnelChainServiceConfig_DefaultListenAddrWhenConnectIPEmpty(t *testing.T) {
 	node := &nodeRecord{TCPListenAddr: "[::]"}
 	chain := tunnelRuntimeNode{Protocol: "tls", Port: 21001}

go-backend/internal/http/handler/mutations.go

@@ -25,6 +25,8 @@ import (
 	"gorm.io/gorm"
 )
 
+const tunnelServiceBindRetryDelay = 150 * time.Millisecond
+
 func (h *Handler) userCreate(w http.ResponseWriter, r *http.Request) {
 	if r.Method != http.MethodPost {
 		response.WriteJSON(w, response.ErrDefault("请求失败"))
@@ -2584,7 +2586,7 @@ func (h *Handler) applyTunnelRuntime(state *tunnelCreateState) ([]int64, []int64
 			createdChains = append(createdChains, chainNode.NodeID)
 
 			serviceData := buildTunnelChainServiceConfig(state.TunnelID, chainNode, state.Nodes[chainNode.NodeID])
-			if _, err := h.sendNodeCommand(chainNode.NodeID, "AddService", serviceData, true, false); err != nil {
+			if err := h.addTunnelServiceOnNode(chainNode.NodeID, state.TunnelID, serviceData); err != nil {
 				return createdChains, createdServices, fmt.Errorf("转发链节点 %s 下发服务失败: %w", nodeDisplayName(state.Nodes[chainNode.NodeID]), err)
 			}
 			createdServices = append(createdServices, chainNode.NodeID)
@@ -2596,7 +2598,7 @@ func (h *Handler) applyTunnelRuntime(state *tunnelCreateState) ([]int64, []int64
 			continue
 		}
 		serviceData := buildTunnelChainServiceConfig(state.TunnelID, outNode, state.Nodes[outNode.NodeID])
-		if _, err := h.sendNodeCommand(outNode.NodeID, "AddService", serviceData, true, false); err != nil {
+		if err := h.addTunnelServiceOnNode(outNode.NodeID, state.TunnelID, serviceData); err != nil {
 			return createdChains, createdServices, fmt.Errorf("出口节点 %s 下发服务失败: %w", nodeDisplayName(state.Nodes[outNode.NodeID]), err)
 		}
 		createdServices = append(createdServices, outNode.NodeID)
@@ -2605,6 +2607,44 @@ func (h *Handler) applyTunnelRuntime(state *tunnelCreateState) ([]int64, []int64
 	return createdChains, createdServices, nil
 }
 
+func retryTunnelServiceAddWithCleanup(add func() error, cleanup func() error, wait time.Duration) error {
+	if add == nil {
+		return errors.New("invalid tunnel service add callback")
+	}
+	err := add()
+	if err == nil || !isAddressAlreadyInUseError(err) {
+		return err
+	}
+	if cleanup == nil {
+		return err
+	}
+	if cleanupErr := cleanup(); cleanupErr != nil {
+		return cleanupErr
+	}
+	if wait > 0 {
+		time.Sleep(wait)
+	}
+	return add()
+}
+
+func (h *Handler) addTunnelServiceOnNode(nodeID, tunnelID int64, serviceData []map[string]interface{}) error {
+	if h == nil {
+		return errors.New("invalid tunnel service context")
+	}
+	serviceName := fmt.Sprintf("%d_tls", tunnelID)
+	return retryTunnelServiceAddWithCleanup(
+		func() error {
+			_, err := h.sendNodeCommand(nodeID, "AddService", serviceData, true, false)
+			return err
+		},
+		func() error {
+			_, err := h.sendNodeCommand(nodeID, "DeleteService", map[string]interface{}{"services": []string{serviceName}}, false, true)
+			return err
+		},
+		tunnelServiceBindRetryDelay,
+	)
+}
+
 func (h *Handler) rollbackTunnelRuntime(chainNodeIDs, serviceNodeIDs []int64, tunnelID int64) {
 	if h == nil || tunnelID <= 0 {
 		return