fix(vpn): handle VPN forwarding mode downgrades and support runtime VPN config updates

ts/classes.dcrouter.ts

@@ -26,6 +26,7 @@ import { RadiusServer, type IRadiusServerConfig } from './radius/index.js';
 import { RemoteIngressManager, TunnelManager } from './remoteingress/index.js';
 import { VpnManager, type IVpnManagerConfig } from './vpn/index.js';
 import { RouteConfigManager, ApiTokenManager, ReferenceResolver, DbSeeder, TargetProfileManager } from './config/index.js';
+import type { TIpAllowEntry } from './config/classes.route-config-manager.js';
 import { SecurityLogger, ContentScanner, IPReputationChecker } from './security/index.js';
 import { type IHttp3Config, augmentRoutesWithHttp3 } from './http3/index.js';
 import { DnsManager } from './dns/manager.dns.js';
@@ -565,20 +566,7 @@ export class DcRouter {
             this.routeConfigManager = new RouteConfigManager(
               () => this.smartProxy,
               () => this.options.http3,
-              this.options.vpnConfig?.enabled
-                ? (route: import('../ts_interfaces/data/remoteingress.js').IDcRouterRouteConfig, routeId?: string) => {
-                    if (!this.vpnManager || !this.targetProfileManager) {
-                      // VPN not ready yet — deny all until re-apply after VPN starts
-                      return [];
-                    }
-                    return this.targetProfileManager.getMatchingClientIps(
-                      route,
-                      routeId,
-                      this.vpnManager.listClients(),
-                      this.routeConfigManager?.getRoutes() || new Map(),
-                    );
-                  }
-                : undefined,
+              this.createVpnRouteAllowListResolver(),
               this.referenceResolver,
               // Sync routes to RemoteIngressManager whenever routes change,
               // then push updated derived ports to the Rust hub binary
@@ -2292,6 +2280,32 @@ export class DcRouter {
   /**
    * Set up VPN server for VPN-based route access control.
    */
+  private createVpnRouteAllowListResolver(): ((
+    route: import('../ts_interfaces/data/remoteingress.js').IDcRouterRouteConfig,
+    routeId?: string,
+  ) => TIpAllowEntry[]) | undefined {
+    if (!this.options.vpnConfig?.enabled) {
+      return undefined;
+    }
+
+    return (
+      route: import('../ts_interfaces/data/remoteingress.js').IDcRouterRouteConfig,
+      routeId?: string,
+    ) => {
+      if (!this.vpnManager || !this.targetProfileManager) {
+        // VPN not ready yet — deny all until re-apply after VPN starts.
+        return [];
+      }
+
+      return this.targetProfileManager.getMatchingClientIps(
+        route,
+        routeId,
+        this.vpnManager.listClients(),
+        this.routeConfigManager?.getRoutes() || new Map(),
+      );
+    };
+  }
+
   private async setupVpnServer(): Promise<void> {
     if (!this.options.vpnConfig?.enabled) {
       return;
@@ -2441,6 +2455,29 @@ export class DcRouter {
 
     logger.log('info', 'RADIUS configuration updated');
   }
+
+  /**
+   * Update VPN configuration at runtime.
+   */
+  public async updateVpnConfig(config: IDcRouterOptions['vpnConfig']): Promise<void> {
+    if (this.vpnManager) {
+      await this.vpnManager.stop();
+      this.vpnManager = undefined;
+    }
+
+    this.options.vpnConfig = config;
+    this.vpnDomainIpCache.clear();
+    this.warnedWildcardVpnDomains.clear();
+    this.routeConfigManager?.setVpnClientIpsResolver(this.createVpnRouteAllowListResolver());
+
+    if (this.options.vpnConfig?.enabled) {
+      await this.setupVpnServer();
+    } else {
+      await this.routeConfigManager?.applyRoutes();
+    }
+
+    logger.log('info', 'VPN configuration updated');
+  }
 }
 
 // Re-export email server types for convenience