fix(smartproxy): Correct NFTables forwarding handling to avoid premature connection termination and add comprehensive tests

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartproxy',
-  version: '19.3.4',
+  version: '19.3.5',
   description: 'A powerful proxy package with unified route-based configuration for high traffic management. Features include SSL/TLS support, flexible routing patterns, WebSocket handling, advanced security options, and automatic ACME certificate management.'
 }

ts/proxies/smart-proxy/route-connection-handler.ts

@@ -339,21 +339,6 @@ export class RouteConnectionHandler {
       );
     }
 
-    // Check if this route uses NFTables for forwarding
-    if (route.action.forwardingEngine === 'nftables') {
-      // For NFTables routes, we don't need to do anything at the application level
-      // The packet is forwarded at the kernel level
-
-      // Log the connection
-      console.log(
-        `[${connectionId}] Connection forwarded by NFTables: ${record.remoteIP} -> port ${record.localPort}`
-      );
-
-      // Just close the socket in our application since it's handled at kernel level
-      socket.end();
-      this.connectionManager.cleanupConnection(record, 'nftables_handled');
-      return;
-    }
 
     // Handle the route based on its action type
     switch (route.action.type) {
@@ -391,10 +376,13 @@ export class RouteConnectionHandler {
 
     // Check if this route uses NFTables for forwarding
     if (action.forwardingEngine === 'nftables') {
-      // Log detailed information about NFTables-handled connection
+      // NFTables handles packet forwarding at the kernel level
+      // The application should NOT interfere with these connections
+      
+      // Just log the connection for monitoring purposes
       if (this.settings.enableDetailedLogging) {
         console.log(
-          `[${record.id}] Connection forwarded by NFTables (kernel-level): ` +
+          `[${record.id}] NFTables forwarding (kernel-level): ` +
             `${record.remoteIP}:${socket.remotePort} -> ${socket.localAddress}:${record.localPort}` +
             ` (Route: "${route.name || 'unnamed'}", Domain: ${record.lockedDomain || 'n/a'})`
         );
@@ -420,14 +408,8 @@ export class RouteConnectionHandler {
         }
       }
 
-      // This connection is handled at the kernel level, no need to process at application level
-      // Close the socket gracefully in our application layer
-      socket.end();
-
-      // Mark the connection as handled by NFTables for proper cleanup
-      record.nftablesHandled = true;
-      this.connectionManager.initiateCleanupOnce(record, 'nftables_handled');
-      return;
+      // For NFTables routes, continue processing the connection normally
+      // since the packet forwarding happens transparently at the kernel level
     }
 
     // We should have a target configuration for forwarding