feat: auto-fallback to default bind IP when invalid bind address detected

When a forward service is updated with a bind IP that doesn't exist on the
host network interfaces, the system now automatically falls back to the
default bind address (listening on all interfaces) instead of failing.

- Added syncForwardServicesWithWarnings to collect fallback warnings
- Implemented fallbackForwardPortToDefaultBind for graceful degradation
- Added UpdateForwardPortBindIP repository method to persist fallback
- Enhanced error detection for 'cannot assign requested address' errors
- Frontend displays warning toasts when fallback occurs
- Added comprehensive unit tests for new error detection functions

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

@@ -223,21 +223,27 @@ func (h *Handler) listUserTunnelIDsByUser(userID int64) ([]int64, error) {
 }
 
 func (h *Handler) syncForwardServices(forward *forwardRecord, method string, allowFallbackAdd bool) error {
+	_, err := h.syncForwardServicesWithWarnings(forward, method, allowFallbackAdd)
+	return err
+}
+
+func (h *Handler) syncForwardServicesWithWarnings(forward *forwardRecord, method string, allowFallbackAdd bool) ([]string, error) {
 	if h == nil || forward == nil {
-		return errors.New("invalid forward sync context")
+		return nil, errors.New("invalid forward sync context")
 	}
 
 	tunnel, err := h.getTunnelRecord(forward.TunnelID)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	ports, err := h.listForwardPorts(forward.ID)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	if len(ports) == 0 {
-		return errors.New("转发入口端口不存在")
+		return nil, errors.New("转发入口端口不存在")
 	}
+	warnings := make([]string, 0)
 
 	// Determine limiter from forward's SpeedID first, fallback to UserTunnel's limiter
 	var limiterID *int64
@@ -258,7 +264,7 @@ func (h *Handler) syncForwardServices(forward *forwardRecord, method string, all
 		var utSpeed *int
 		_, utLimiterID, utSpeed, err = h.resolveUserTunnelAndLimiter(forward.UserID, forward.TunnelID)
 		if err != nil {
-			return err
+			return nil, err
 		}
 		limiterID = utLimiterID
 		speed = utSpeed
@@ -267,33 +273,69 @@ func (h *Handler) syncForwardServices(forward *forwardRecord, method string, all
 	serviceBase := buildForwardServiceBase(forward.ID, forward.UserID, 0)
 	tunnelTLSProtocol, err := h.isTunnelSelectedTLSProtocol(forward.TunnelID)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	for _, fp := range ports {
 		if limiterID != nil && speed != nil {
 			if err := h.ensureLimiterOnNode(fp.NodeID, *limiterID, *speed); err != nil {
-				return err
+				return nil, err
 			}
 		}
 
 		node, err := h.getNodeRecord(fp.NodeID)
 		if err != nil {
-			return err
+			return nil, err
 		}
 		services := buildForwardServiceConfigs(serviceBase, forward, tunnel, node, fp.Port, strings.TrimSpace(fp.InIP), limiterID, tunnelTLSProtocol)
 		_, err = h.sendNodeCommand(node.ID, method, services, true, false)
 		if err != nil && allowFallbackAdd && method == "UpdateService" {
 			_, err = h.sendNodeCommand(node.ID, "AddService", services, true, false)
 		}
-		if err != nil && strings.EqualFold(strings.TrimSpace(method), "UpdateService") && isBindAddressInUseError(err) {
+		if err != nil && strings.EqualFold(strings.TrimSpace(method), "UpdateService") && isAddressAlreadyInUseError(err) {
 			err = h.rebindForwardServiceOnSelfOccupiedPort(forward, node, fp.Port, services)
 		}
+		if err != nil && strings.EqualFold(strings.TrimSpace(method), "UpdateService") && isCannotAssignRequestedAddressError(err) {
+			var warning string
+			warning, err = h.fallbackForwardPortToDefaultBind(forward, tunnel, node, fp, serviceBase, limiterID, tunnelTLSProtocol)
+			if err == nil && warning != "" {
+				warnings = append(warnings, warning)
+			}
+		}
 		if err != nil {
-			return fmt.Errorf("节点 %s 下发失败: %w", node.Name, err)
+			return warnings, fmt.Errorf("节点 %s 下发失败: %w", node.Name, err)
 		}
 	}
-	return nil
+	return warnings, nil
+}
+
+func (h *Handler) fallbackForwardPortToDefaultBind(forward *forwardRecord, tunnel *tunnelRecord, node *nodeRecord, fp forwardPortRecord, serviceBase string, limiterID *int64, tunnelTLSProtocol bool) (string, error) {
+	if h == nil || forward == nil || tunnel == nil || node == nil {
+		return "", errors.New("invalid bind fallback context")
+	}
+	if fp.Port <= 0 {
+		return "", errors.New("invalid forward port")
+	}
+	explicitBindIP := strings.TrimSpace(fp.InIP)
+	if explicitBindIP == "" {
+		return "", errors.New("default bind address cannot be assigned")
+	}
+
+	if err := h.deleteForwardServicesOnNode(forward, node.ID); err != nil {
+		return "", err
+	}
+
+	time.Sleep(150 * time.Millisecond)
+	defaultServices := buildForwardServiceConfigs(serviceBase, forward, tunnel, node, fp.Port, "", limiterID, tunnelTLSProtocol)
+	if _, err := h.sendNodeCommand(node.ID, "AddService", defaultServices, true, false); err != nil {
+		return "", err
+	}
+	if err := h.repo.UpdateForwardPortBindIP(forward.ID, node.ID, fp.Port, ""); err != nil {
+		return "", err
+	}
+
+	warning := fmt.Sprintf("节点 %s 监听IP %s 不在主机网卡地址中，已自动回退为默认监听IP", strings.TrimSpace(node.Name), explicitBindIP)
+	return warning, nil
 }
 
 func (h *Handler) rebindForwardServiceOnSelfOccupiedPort(forward *forwardRecord, node *nodeRecord, port int, services []map[string]interface{}) error {
@@ -1385,8 +1427,30 @@ func isBindAddressInUseError(err error) bool {
 	if msg == "" {
 		return false
 	}
-	if strings.Contains(msg, "address already in use") {
+	return isAddressAlreadyInUseMessage(msg) || strings.Contains(msg, "cannot assign requested address")
-		return true
+}
+
+func isAddressAlreadyInUseError(err error) bool {
+	if err == nil {
+		return false
+	}
+	return isAddressAlreadyInUseMessage(strings.ToLower(strings.TrimSpace(err.Error())))
+}
+
+func isAddressAlreadyInUseMessage(msg string) bool {
+	if msg == "" {
+		return false
+	}
+	return strings.Contains(msg, "address already in use")
+}
+
+func isCannotAssignRequestedAddressError(err error) bool {
+	if err == nil {
+		return false
+	}
+	msg := strings.ToLower(strings.TrimSpace(err.Error()))
+	if msg == "" {
+		return false
 	}
 	return strings.Contains(msg, "cannot assign requested address")
 }

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

@@ -82,6 +82,24 @@ func TestIsBindAddressInUseError(t *testing.T) {
 	}
 }
 
+func TestIsAddressAlreadyInUseError(t *testing.T) {
+	if !isAddressAlreadyInUseError(errors.New("listen tcp [::]:10001: bind: address already in use")) {
+		t.Fatalf("address already in use should be detected")
+	}
+	if isAddressAlreadyInUseError(errors.New("listen tcp4 13.228.170.187:16765: bind: cannot assign requested address")) {
+		t.Fatalf("cannot assign requested address should not be treated as address-in-use")
+	}
+}
+
+func TestIsCannotAssignRequestedAddressError(t *testing.T) {
+	if !isCannotAssignRequestedAddressError(errors.New("listen tcp4 13.228.170.187:16765: bind: cannot assign requested address")) {
+		t.Fatalf("cannot assign requested address should be detected")
+	}
+	if isCannotAssignRequestedAddressError(errors.New("listen tcp [::]:10001: bind: address already in use")) {
+		t.Fatalf("address already in use should not be treated as cannot-assign")
+	}
+}
+
 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/mutations.go

@@ -1325,11 +1325,16 @@ func (h *Handler) forwardUpdate(w http.ResponseWriter, r *http.Request) {
 		response.WriteJSON(w, response.Err(-2, err.Error()))
 		return
 	}
-	if err := h.syncForwardServices(updatedForward, "UpdateService", true); err != nil {
+	warnings, err := h.syncForwardServicesWithWarnings(updatedForward, "UpdateService", true)
+	if err != nil {
 		h.rollbackForwardMutation(forward, oldPorts)
 		response.WriteJSON(w, response.ErrDefault(err.Error()))
 		return
 	}
+	if len(warnings) > 0 {
+		response.WriteJSON(w, response.OK(map[string]interface{}{"warnings": warnings}))
+		return
+	}
 	response.WriteJSON(w, response.OKEmpty())
 }
 

go-backend/internal/store/repo/repository_mutations.go

@@ -720,6 +720,18 @@ func (r *Repository) ReplaceForwardPorts(forwardID int64, entries []struct {
 	})
 }
 
+func (r *Repository) UpdateForwardPortBindIP(forwardID, nodeID int64, port int, inIP string) error {
+	if r == nil || r.db == nil {
+		return errors.New("repository not initialized")
+	}
+	if forwardID <= 0 || nodeID <= 0 || port <= 0 {
+		return nil
+	}
+	return r.db.Model(&model.ForwardPort{}).
+		Where("forward_id = ? AND node_id = ? AND port = ?", forwardID, nodeID, port).
+		Update("in_ip", sql.NullString{String: inIP, Valid: strings.TrimSpace(inIP) != ""}).Error
+}
+
 func (r *Repository) RollbackForwardFields(id, userID int64, userName, name string, tunnelID int64, remoteAddr, strategy string, status int, speedID interface{}, now int64) {
 	if r == nil || r.db == nil {
 		return

plans/005-forward-invalid-bindip-fallback-default.md

@@ -0,0 +1,11 @@
+# 005 Forward Invalid BindIP Fallback Default
+
+## Checklist
+
+- [x] Split forward service bind failures into address-in-use and cannot-assign classes.
+- [x] Keep self-occupy release/rebind only for address-in-use conflicts.
+- [x] Add fallback path for cannot-assign: switch to default listener bind and retry service creation.
+- [x] Persist fallback result to DB by clearing `forward_port.in_ip` for affected node+port.
+- [x] Return non-blocking warning in forward update response when fallback occurs.
+- [x] Show warning toast in forward edit UI while still treating operation as success.
+- [x] Run focused backend tests for touched handler/repo packages.

vite-frontend/src/pages/forward.tsx

@@ -1419,6 +1419,18 @@ export default function ForwardPage() {
       }
 
       if (res.code === 0) {
+        const warningItems = Array.isArray((res as any).data?.warnings)
+          ? (res as any).data.warnings
+              .map((item: unknown) => (typeof item === "string" ? item.trim() : ""))
+              .filter((item: string) => item)
+          : [];
+
+        warningItems.forEach((warning: string) => {
+          toast(warning, {
+            icon: "⚠️",
+            duration: 5000,
+          });
+        });
         toast.success(isEdit ? "修改成功" : "创建成功");
         setModalOpen(false);
         loadData();