Add tests for connect-disconnect and error handling in SmartProxy

readme.hints.md

@@ -524,3 +524,62 @@ if (!record) {
 
 ### Migration Notes
 No configuration changes needed. The improvements are automatic and backward compatible.
+
+## Early Client Disconnect Handling (v19.5.13+)
+
+### Issue
+Connections were accumulating when clients connected but disconnected before sending data or during routing. This occurred in two scenarios:
+1. **TLS Path**: Clients connecting and disconnecting before sending initial TLS handshake data
+2. **Non-TLS Immediate Routing**: Clients disconnecting while backend connection was being established
+
+### Root Cause
+1. **Missing Cleanup Handlers**: During initial data wait and immediate routing, no close/end handlers were attached to catch early disconnections
+2. **Race Condition**: Backend connection attempts continued even after client disconnected, causing unhandled errors
+3. **Timing Window**: Between accepting connection and establishing full bidirectional flow, disconnections weren't properly handled
+
+### Solution
+1. **TLS Path Fix**: Added close/end handlers during initial data wait (lines 224-253 in route-connection-handler.ts)
+2. **Immediate Routing Fix**: Used `setupSocketHandlers` for proper handler attachment (lines 180-205)
+3. **Backend Error Handling**: Check if connection already closed before handling backend errors (line 1144)
+
+### Changes Made
+```typescript
+// 1. TLS path - handle disconnect before initial data
+socket.once('close', () => {
+  if (!initialDataReceived) {
+    this.connectionManager.cleanupConnection(record, 'closed_before_data');
+  }
+});
+
+// 2. Immediate routing path - proper handler setup
+setupSocketHandlers(socket, (reason) => {
+  if (!record.outgoing || record.outgoing.readyState !== 'open') {
+    if (record.outgoing && !record.outgoing.destroyed) {
+      record.outgoing.destroy(); // Abort pending backend connection
+    }
+    this.connectionManager.cleanupConnection(record, reason);
+  }
+}, undefined, 'immediate-route-client');
+
+// 3. Backend connection error handling
+onError: (error) => {
+  if (record.connectionClosed) {
+    logger.log('debug', 'Backend connection failed but client already disconnected');
+    return; // Client already gone, nothing to clean up
+  }
+  // ... normal error handling
+}
+```
+
+### Test Coverage
+- `test/test.connect-disconnect-cleanup.node.ts` - Comprehensive test for early disconnect scenarios
+- Tests verify connection count stays at 0 even with rapid connect/disconnect patterns
+- Covers immediate disconnect, delayed disconnect, and mixed patterns
+
+### Performance Impact
+- **Positive**: No more connection accumulation from early disconnects
+- **Positive**: Immediate cleanup reduces memory usage
+- **Positive**: Prevents resource exhaustion from rapid reconnection attempts
+
+### Migration Notes
+No configuration changes needed. The fix is automatic and backward compatible.

test/test.connect-disconnect-cleanup.node.ts

@@ -0,0 +1,242 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import * as net from 'net';
+import * as plugins from '../ts/plugins.js';
+
+// Import SmartProxy and configurations
+import { SmartProxy } from '../ts/index.js';
+
+tap.test('should handle clients that connect and immediately disconnect without sending data', async () => {
+  console.log('\n=== Testing Connect-Disconnect Cleanup ===');
+  
+  // Create a SmartProxy instance
+  const proxy = new SmartProxy({
+    ports: [8560],
+    enableDetailedLogging: false,
+    initialDataTimeout: 5000, // 5 second timeout for initial data
+    routes: [{
+      name: 'test-route',
+      match: { ports: 8560 },
+      action: {
+        type: 'forward',
+        target: {
+          host: 'localhost',
+          port: 9999  // Non-existent port
+        }
+      }
+    }]
+  });
+  
+  // Start the proxy
+  await proxy.start();
+  console.log('✓ Proxy started on port 8560');
+  
+  // Helper to get active connection count
+  const getActiveConnections = () => {
+    const connectionManager = (proxy as any).connectionManager;
+    return connectionManager ? connectionManager.getConnectionCount() : 0;
+  };
+  
+  const initialCount = getActiveConnections();
+  console.log(`Initial connection count: ${initialCount}`);
+  
+  // Test 1: Connect and immediately disconnect without sending data
+  console.log('\n--- Test 1: Immediate disconnect ---');
+  const connectionCounts: number[] = [];
+  
+  for (let i = 0; i < 10; i++) {
+    const client = new net.Socket();
+    
+    // Connect and immediately destroy
+    client.connect(8560, 'localhost', () => {
+      // Connected - immediately destroy without sending data
+      client.destroy();
+    });
+    
+    // Wait a tiny bit
+    await new Promise(resolve => setTimeout(resolve, 10));
+    
+    const count = getActiveConnections();
+    connectionCounts.push(count);
+    if ((i + 1) % 5 === 0) {
+      console.log(`After ${i + 1} connect/disconnect cycles: ${count} active connections`);
+    }
+  }
+  
+  // Wait a bit for cleanup
+  await new Promise(resolve => setTimeout(resolve, 500));
+  
+  const afterImmediateDisconnect = getActiveConnections();
+  console.log(`After immediate disconnect test: ${afterImmediateDisconnect} active connections`);
+  
+  // Test 2: Connect, wait a bit, then disconnect without sending data
+  console.log('\n--- Test 2: Delayed disconnect ---');
+  
+  for (let i = 0; i < 5; i++) {
+    const client = new net.Socket();
+    
+    client.on('error', () => {
+      // Ignore errors
+    });
+    
+    client.connect(8560, 'localhost', () => {
+      // Wait 100ms then disconnect without sending data
+      setTimeout(() => {
+        if (!client.destroyed) {
+          client.destroy();
+        }
+      }, 100);
+    });
+  }
+  
+  // Check count immediately
+  const duringDelayed = getActiveConnections();
+  console.log(`During delayed disconnect test: ${duringDelayed} active connections`);
+  
+  // Wait for cleanup
+  await new Promise(resolve => setTimeout(resolve, 1000));
+  
+  const afterDelayedDisconnect = getActiveConnections();
+  console.log(`After delayed disconnect test: ${afterDelayedDisconnect} active connections`);
+  
+  // Test 3: Mix of immediate and delayed disconnects
+  console.log('\n--- Test 3: Mixed disconnect patterns ---');
+  
+  const promises = [];
+  for (let i = 0; i < 20; i++) {
+    promises.push(new Promise<void>((resolve) => {
+      const client = new net.Socket();
+      
+      client.on('error', () => {
+        resolve();
+      });
+      
+      client.on('close', () => {
+        resolve();
+      });
+      
+      client.connect(8560, 'localhost', () => {
+        if (i % 2 === 0) {
+          // Half disconnect immediately
+          client.destroy();
+        } else {
+          // Half wait 50ms
+          setTimeout(() => {
+            if (!client.destroyed) {
+              client.destroy();
+            }
+          }, 50);
+        }
+      });
+      
+      // Failsafe timeout
+      setTimeout(() => resolve(), 200);
+    }));
+  }
+  
+  // Wait for all to complete
+  await Promise.all(promises);
+  
+  const duringMixed = getActiveConnections();
+  console.log(`During mixed test: ${duringMixed} active connections`);
+  
+  // Final cleanup wait
+  await new Promise(resolve => setTimeout(resolve, 1000));
+  
+  const finalCount = getActiveConnections();
+  console.log(`\nFinal connection count: ${finalCount}`);
+  
+  // Stop the proxy
+  await proxy.stop();
+  console.log('✓ Proxy stopped');
+  
+  // Verify all connections were cleaned up
+  expect(finalCount).toEqual(initialCount);
+  expect(afterImmediateDisconnect).toEqual(initialCount);
+  expect(afterDelayedDisconnect).toEqual(initialCount);
+  
+  // Check that connections didn't accumulate during the test
+  const maxCount = Math.max(...connectionCounts);
+  console.log(`\nMax connection count during immediate disconnect test: ${maxCount}`);
+  expect(maxCount).toBeLessThan(3); // Should stay very low
+  
+  console.log('\n✅ PASS: Connect-disconnect cleanup working correctly!');
+});
+
+tap.test('should handle clients that error during connection', async () => {
+  console.log('\n=== Testing Connection Error Cleanup ===');
+  
+  const proxy = new SmartProxy({
+    ports: [8561],
+    enableDetailedLogging: false,
+    routes: [{
+      name: 'test-route',
+      match: { ports: 8561 },
+      action: {
+        type: 'forward',
+        target: {
+          host: 'localhost',
+          port: 9999
+        }
+      }
+    }]
+  });
+  
+  await proxy.start();
+  console.log('✓ Proxy started on port 8561');
+  
+  const getActiveConnections = () => {
+    const connectionManager = (proxy as any).connectionManager;
+    return connectionManager ? connectionManager.getConnectionCount() : 0;
+  };
+  
+  const initialCount = getActiveConnections();
+  console.log(`Initial connection count: ${initialCount}`);
+  
+  // Create connections that will error
+  const promises = [];
+  for (let i = 0; i < 10; i++) {
+    promises.push(new Promise<void>((resolve) => {
+      const client = new net.Socket();
+      
+      client.on('error', () => {
+        resolve();
+      });
+      
+      client.on('close', () => {
+        resolve();
+      });
+      
+      // Connect to proxy
+      client.connect(8561, 'localhost', () => {
+        // Force an error by writing invalid data then destroying
+        try {
+          client.write(Buffer.alloc(1024 * 1024)); // Large write
+          client.destroy();
+        } catch (e) {
+          // Ignore
+        }
+      });
+      
+      // Timeout
+      setTimeout(() => resolve(), 500);
+    }));
+  }
+  
+  await Promise.all(promises);
+  console.log('✓ All error connections completed');
+  
+  // Wait for cleanup
+  await new Promise(resolve => setTimeout(resolve, 500));
+  
+  const finalCount = getActiveConnections();
+  console.log(`Final connection count: ${finalCount}`);
+  
+  await proxy.stop();
+  console.log('✓ Proxy stopped');
+  
+  expect(finalCount).toEqual(initialCount);
+  
+  console.log('\n✅ PASS: Connection error cleanup working correctly!');
+});
+
+tap.start();

test/test.connection-cleanup-comprehensive.node.ts

@@ -0,0 +1,279 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import * as net from 'net';
+import * as plugins from '../ts/plugins.js';
+
+// Import SmartProxy and configurations
+import { SmartProxy } from '../ts/index.js';
+
+tap.test('comprehensive connection cleanup test - all scenarios', async () => {
+  console.log('\n=== Comprehensive Connection Cleanup Test ===');
+  
+  // Create a SmartProxy instance
+  const proxy = new SmartProxy({
+    ports: [8570, 8571], // One for immediate routing, one for TLS
+    enableDetailedLogging: false,
+    initialDataTimeout: 2000,
+    socketTimeout: 5000,
+    routes: [
+      {
+        name: 'non-tls-route',
+        match: { ports: 8570 },
+        action: {
+          type: 'forward',
+          target: {
+            host: 'localhost',
+            port: 9999  // Non-existent port
+          }
+        }
+      },
+      {
+        name: 'tls-route',
+        match: { ports: 8571 },
+        action: {
+          type: 'forward',
+          target: {
+            host: 'localhost',
+            port: 9999  // Non-existent port
+          },
+          tls: {
+            mode: 'passthrough'
+          }
+        }
+      }
+    ]
+  });
+  
+  // Start the proxy
+  await proxy.start();
+  console.log('✓ Proxy started on ports 8570 (non-TLS) and 8571 (TLS)');
+  
+  // Helper to get active connection count
+  const getActiveConnections = () => {
+    const connectionManager = (proxy as any).connectionManager;
+    return connectionManager ? connectionManager.getConnectionCount() : 0;
+  };
+  
+  const initialCount = getActiveConnections();
+  console.log(`Initial connection count: ${initialCount}`);
+  
+  // Test 1: Rapid ECONNREFUSED retries (from original issue)
+  console.log('\n--- Test 1: Rapid ECONNREFUSED retries ---');
+  for (let i = 0; i < 10; i++) {
+    await new Promise<void>((resolve) => {
+      const client = new net.Socket();
+      
+      client.on('error', () => {
+        client.destroy();
+        resolve();
+      });
+      
+      client.on('close', () => {
+        resolve();
+      });
+      
+      client.connect(8570, 'localhost', () => {
+        // Send data to trigger routing
+        client.write('GET / HTTP/1.1\r\nHost: test.com\r\n\r\n');
+      });
+      
+      setTimeout(() => {
+        if (!client.destroyed) {
+          client.destroy();
+        }
+        resolve();
+      }, 100);
+    });
+    
+    if ((i + 1) % 5 === 0) {
+      const count = getActiveConnections();
+      console.log(`After ${i + 1} ECONNREFUSED retries: ${count} active connections`);
+    }
+  }
+  
+  // Test 2: Connect without sending data (immediate disconnect)
+  console.log('\n--- Test 2: Connect without sending data ---');
+  for (let i = 0; i < 10; i++) {
+    const client = new net.Socket();
+    
+    client.on('error', () => {
+      // Ignore
+    });
+    
+    // Connect to non-TLS port and immediately disconnect
+    client.connect(8570, 'localhost', () => {
+      client.destroy();
+    });
+    
+    await new Promise(resolve => setTimeout(resolve, 10));
+  }
+  
+  const afterNoData = getActiveConnections();
+  console.log(`After connect-without-data test: ${afterNoData} active connections`);
+  
+  // Test 3: TLS connections that disconnect before handshake
+  console.log('\n--- Test 3: TLS early disconnect ---');
+  for (let i = 0; i < 10; i++) {
+    const client = new net.Socket();
+    
+    client.on('error', () => {
+      // Ignore
+    });
+    
+    // Connect to TLS port but disconnect before sending handshake
+    client.connect(8571, 'localhost', () => {
+      // Wait 50ms then disconnect (before initial data timeout)
+      setTimeout(() => {
+        client.destroy();
+      }, 50);
+    });
+    
+    await new Promise(resolve => setTimeout(resolve, 100));
+  }
+  
+  const afterTlsEarly = getActiveConnections();
+  console.log(`After TLS early disconnect test: ${afterTlsEarly} active connections`);
+  
+  // Test 4: Mixed pattern - simulating real-world chaos
+  console.log('\n--- Test 4: Mixed chaos pattern ---');
+  const promises = [];
+  
+  for (let i = 0; i < 30; i++) {
+    promises.push(new Promise<void>((resolve) => {
+      const client = new net.Socket();
+      const port = i % 2 === 0 ? 8570 : 8571;
+      
+      client.on('error', () => {
+        resolve();
+      });
+      
+      client.on('close', () => {
+        resolve();
+      });
+      
+      client.connect(port, 'localhost', () => {
+        const scenario = i % 5;
+        
+        switch (scenario) {
+          case 0:
+            // Immediate disconnect
+            client.destroy();
+            break;
+          case 1:
+            // Send data then disconnect
+            client.write('GET / HTTP/1.1\r\nHost: test.com\r\n\r\n');
+            setTimeout(() => client.destroy(), 20);
+            break;
+          case 2:
+            // Disconnect after delay
+            setTimeout(() => client.destroy(), 100);
+            break;
+          case 3:
+            // Send partial TLS handshake
+            if (port === 8571) {
+              client.write(Buffer.from([0x16, 0x03, 0x01])); // Partial TLS
+            }
+            setTimeout(() => client.destroy(), 50);
+            break;
+          case 4:
+            // Just let it timeout
+            break;
+        }
+      });
+      
+      // Failsafe
+      setTimeout(() => {
+        if (!client.destroyed) {
+          client.destroy();
+        }
+        resolve();
+      }, 500);
+    }));
+    
+    // Small delay between connections
+    if (i % 5 === 0) {
+      await new Promise(resolve => setTimeout(resolve, 10));
+    }
+  }
+  
+  await Promise.all(promises);
+  console.log('✓ Chaos test completed');
+  
+  // Wait for any cleanup
+  await new Promise(resolve => setTimeout(resolve, 1000));
+  
+  const afterChaos = getActiveConnections();
+  console.log(`After chaos test: ${afterChaos} active connections`);
+  
+  // Test 5: NFTables route (should cleanup properly)
+  console.log('\n--- Test 5: NFTables route cleanup ---');
+  const nftProxy = new SmartProxy({
+    ports: [8572],
+    enableDetailedLogging: false,
+    routes: [{
+      name: 'nftables-route',
+      match: { ports: 8572 },
+      action: {
+        type: 'forward',
+        forwardingEngine: 'nftables',
+        target: {
+          host: 'localhost',
+          port: 9999
+        }
+      }
+    }]
+  });
+  
+  await nftProxy.start();
+  
+  const getNftConnections = () => {
+    const connectionManager = (nftProxy as any).connectionManager;
+    return connectionManager ? connectionManager.getConnectionCount() : 0;
+  };
+  
+  // Create NFTables connections
+  for (let i = 0; i < 5; i++) {
+    const client = new net.Socket();
+    
+    client.on('error', () => {
+      // Ignore
+    });
+    
+    client.connect(8572, 'localhost', () => {
+      setTimeout(() => client.destroy(), 50);
+    });
+    
+    await new Promise(resolve => setTimeout(resolve, 100));
+  }
+  
+  await new Promise(resolve => setTimeout(resolve, 500));
+  
+  const nftFinal = getNftConnections();
+  console.log(`NFTables connections after test: ${nftFinal}`);
+  
+  await nftProxy.stop();
+  
+  // Final check on main proxy
+  const finalCount = getActiveConnections();
+  console.log(`\nFinal connection count: ${finalCount}`);
+  
+  // Stop the proxy
+  await proxy.stop();
+  console.log('✓ Proxy stopped');
+  
+  // Verify all connections were cleaned up
+  expect(finalCount).toEqual(initialCount);
+  expect(afterNoData).toEqual(initialCount);
+  expect(afterTlsEarly).toEqual(initialCount);
+  expect(afterChaos).toEqual(initialCount);
+  expect(nftFinal).toEqual(0);
+  
+  console.log('\n✅ PASS: Comprehensive connection cleanup test passed!');
+  console.log('All connection scenarios properly cleaned up:');
+  console.log('- ECONNREFUSED rapid retries');
+  console.log('- Connect without sending data');
+  console.log('- TLS early disconnect');
+  console.log('- Mixed chaos patterns');
+  console.log('- NFTables connections');
+});
+
+tap.start();

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

@@ -176,8 +176,33 @@ export class RouteConnectionHandler {
 
     // If no routes require TLS handling and it's not port 443, route immediately
     if (!needsTlsHandling && localPort !== 443) {
-      // Set up error handler
+      // Set up proper socket handlers for immediate routing
-      socket.on('error', this.connectionManager.handleError('incoming', record));
+      setupSocketHandlers(
+        socket,
+        (reason) => {
+          // Only cleanup if connection hasn't been fully established
+          // Check if outgoing connection exists and is connected
+          if (!record.outgoing || record.outgoing.readyState !== 'open') {
+            logger.log('debug', `Connection ${connectionId} closed during immediate routing: ${reason}`, {
+              connectionId,
+              remoteIP: record.remoteIP,
+              reason,
+              hasOutgoing: !!record.outgoing,
+              outgoingState: record.outgoing?.readyState,
+              component: 'route-handler'
+            });
+            
+            // If there's a pending outgoing connection, destroy it
+            if (record.outgoing && !record.outgoing.destroyed) {
+              record.outgoing.destroy();
+            }
+            
+            this.connectionManager.cleanupConnection(record, reason);
+          }
+        },
+        undefined, // Use default timeout handler
+        'immediate-route-client'
+      );
       
       // Route immediately for non-TLS connections
       this.routeConnection(socket, record, '', undefined);
@@ -221,6 +246,37 @@ export class RouteConnectionHandler {
     // Set up error handler
     socket.on('error', this.connectionManager.handleError('incoming', record));
 
+    // Add close/end handlers to catch immediate disconnections
+    socket.once('close', () => {
+      if (!initialDataReceived) {
+        logger.log('warn', `Connection ${connectionId} closed before sending initial data`, {
+          connectionId,
+          remoteIP: record.remoteIP,
+          component: 'route-handler'
+        });
+        if (initialTimeout) {
+          clearTimeout(initialTimeout);
+          initialTimeout = null;
+        }
+        this.connectionManager.cleanupConnection(record, 'closed_before_data');
+      }
+    });
+
+    socket.once('end', () => {
+      if (!initialDataReceived) {
+        logger.log('debug', `Connection ${connectionId} ended before sending initial data`, {
+          connectionId,
+          remoteIP: record.remoteIP,
+          component: 'route-handler'
+        });
+        if (initialTimeout) {
+          clearTimeout(initialTimeout);
+          initialTimeout = null;
+        }
+        // Don't cleanup on 'end' - wait for 'close'
+      }
+    });
+
     // First data handler to capture initial TLS handshake
     socket.once('data', (chunk: Buffer) => {
       // Clear the initial timeout since we've received data
@@ -927,107 +983,6 @@ export class RouteConnectionHandler {
     }
   }
 
-  /**
-   * Setup improved error handling for the outgoing connection
-   * @deprecated This method is no longer used - error handling is done in createSocketWithErrorHandler
-   */
-  private setupOutgoingErrorHandler(
-    connectionId: string,
-    targetSocket: plugins.net.Socket, 
-    record: IConnectionRecord,
-    socket: plugins.net.Socket,
-    finalTargetHost: string,
-    finalTargetPort: number
-  ): void {
-    targetSocket.once('error', (err) => {
-      // This handler runs only once during the initial connection phase
-      const code = (err as any).code;
-      logger.log('error', 
-        `Connection setup error for ${connectionId} to ${finalTargetHost}:${finalTargetPort}: ${err.message} (${code})`, 
-        {
-          connectionId,
-          targetHost: finalTargetHost,
-          targetPort: finalTargetPort,
-          errorMessage: err.message,
-          errorCode: code,
-          component: 'route-handler'
-        }
-      );
-
-      // Resume the incoming socket to prevent it from hanging
-      socket.resume();
-
-      // Log specific error types for easier debugging
-      if (code === 'ECONNREFUSED') {
-        logger.log('error', 
-          `Connection ${connectionId}: Target ${finalTargetHost}:${finalTargetPort} refused connection. Check if the target service is running and listening on that port.`, 
-          {
-            connectionId,
-            targetHost: finalTargetHost,
-            targetPort: finalTargetPort,
-            recommendation: 'Check if the target service is running and listening on that port.',
-            component: 'route-handler'
-          }
-        );
-      } else if (code === 'ETIMEDOUT') {
-        logger.log('error', 
-          `Connection ${connectionId} to ${finalTargetHost}:${finalTargetPort} timed out. Check network conditions, firewall rules, or if the target is too far away.`, 
-          {
-            connectionId,
-            targetHost: finalTargetHost,
-            targetPort: finalTargetPort,
-            recommendation: 'Check network conditions, firewall rules, or if the target is too far away.',
-            component: 'route-handler'
-          }
-        );
-      } else if (code === 'ECONNRESET') {
-        logger.log('error', 
-          `Connection ${connectionId} to ${finalTargetHost}:${finalTargetPort} was reset. The target might have closed the connection abruptly.`, 
-          {
-            connectionId,
-            targetHost: finalTargetHost,
-            targetPort: finalTargetPort,
-            recommendation: 'The target might have closed the connection abruptly.',
-            component: 'route-handler'
-          }
-        );
-      } else if (code === 'EHOSTUNREACH') {
-        logger.log('error', 
-          `Connection ${connectionId}: Host ${finalTargetHost} is unreachable. Check DNS settings, network routing, or firewall rules.`, 
-          {
-            connectionId,
-            targetHost: finalTargetHost,
-            recommendation: 'Check DNS settings, network routing, or firewall rules.',
-            component: 'route-handler'
-          }
-        );
-      } else if (code === 'ENOTFOUND') {
-        logger.log('error', 
-          `Connection ${connectionId}: DNS lookup failed for ${finalTargetHost}. Check your DNS settings or if the hostname is correct.`, 
-          {
-            connectionId,
-            targetHost: finalTargetHost,
-            recommendation: 'Check your DNS settings or if the hostname is correct.',
-            component: 'route-handler'
-          }
-        );
-      }
-
-      // Clear any existing error handler after connection phase
-      targetSocket.removeAllListeners('error');
-
-      // Re-add the normal error handler for established connections
-      targetSocket.on('error', this.connectionManager.handleError('outgoing', record));
-
-      if (record.outgoingTerminationReason === null) {
-        record.outgoingTerminationReason = 'connection_failed';
-        this.connectionManager.incrementTerminationStat('outgoing', 'connection_failed');
-      }
-
-      // Clean up the connection
-      this.connectionManager.initiateCleanupOnce(record, `connection_failed_${code}`);
-    });
-  }
 
   /**
    * Sets up a direct connection to the target
@@ -1090,6 +1045,16 @@ export class RouteConnectionHandler {
       host: finalTargetHost,
       onError: (error) => {
         // Connection failed - clean up everything immediately
+        // Check if connection record is still valid (client might have disconnected)
+        if (record.connectionClosed) {
+          logger.log('debug', `Backend connection failed but client already disconnected for ${connectionId}`, {
+            connectionId,
+            errorCode: (error as any).code,
+            component: 'route-handler'
+          });
+          return;
+        }
+        
         logger.log('error', 
           `Connection setup error for ${connectionId} to ${finalTargetHost}:${finalTargetPort}: ${error.message} (${(error as any).code})`, 
           {
@@ -1117,10 +1082,12 @@ export class RouteConnectionHandler {
         }
         
         // Resume the incoming socket to prevent it from hanging
+        if (socket && !socket.destroyed) {
           socket.resume();
+        }
         
         // Clean up the incoming socket
-        if (!socket.destroyed) {
+        if (socket && !socket.destroyed) {
           socket.destroy();
         }
         
@@ -1294,7 +1261,7 @@ export class RouteConnectionHandler {
       }
     });
     
-    // Only set up basic properties - everything else happens in onConnect
+    // Set outgoing socket immediately so it can be cleaned up if client disconnects
     record.outgoing = targetSocket;
     record.outgoingStartTime = Date.now();