fix(socket-handler): Fix socket handler race condition by differentiating between async and sync handlers. Now, async socket handlers complete their setup before initial data is emitted, ensuring that no data is lost. Documentation and tests have been updated to reflect this change.

test/test.socket-handler-race.ts

@@ -0,0 +1,83 @@
+import { expect, tap } from '@git.zone/tstest/tapbundle';
+import * as net from 'net';
+import { SmartProxy } from '../ts/index.js';
+
+tap.test('should handle async handler that sets up listeners after delay', async () => {
+  const proxy = new SmartProxy({
+    routes: [{
+      name: 'delayed-setup-handler',
+      match: { ports: 7777 },
+      action: {
+        type: 'socket-handler',
+        socketHandler: async (socket) => {
+          // Simulate async work BEFORE setting up listeners
+          await new Promise(resolve => setTimeout(resolve, 50));
+          
+          // Now set up the listener - with the race condition, this would miss initial data
+          socket.on('data', (data) => {
+            const message = data.toString().trim();
+            socket.write(`RECEIVED: ${message}\n`);
+            if (message === 'close') {
+              socket.end();
+            }
+          });
+          
+          // Send ready message
+          socket.write('HANDLER READY\n');
+        }
+      }
+    }],
+    enableDetailedLogging: false
+  });
+  
+  await proxy.start();
+  
+  // Test connection
+  const client = new net.Socket();
+  let response = '';
+  
+  client.on('data', (data) => {
+    response += data.toString();
+  });
+  
+  await new Promise<void>((resolve, reject) => {
+    client.connect(7777, 'localhost', () => {
+      // Send initial data immediately - this tests the race condition
+      client.write('initial-message\n');
+      resolve();
+    });
+    client.on('error', reject);
+  });
+  
+  // Wait for handler setup and initial data processing
+  await new Promise(resolve => setTimeout(resolve, 150));
+  
+  // Send another message to verify handler is working
+  client.write('test-message\n');
+  
+  // Wait for response
+  await new Promise(resolve => setTimeout(resolve, 50));
+  
+  // Send close command
+  client.write('close\n');
+  
+  // Wait for connection to close
+  await new Promise(resolve => {
+    client.on('close', () => resolve(undefined));
+  });
+  
+  console.log('Response:', response);
+  
+  // Should have received the ready message
+  expect(response).toContain('HANDLER READY');
+  
+  // Should have received the initial message (this would fail with race condition)
+  expect(response).toContain('RECEIVED: initial-message');
+  
+  // Should have received the test message
+  expect(response).toContain('RECEIVED: test-message');
+  
+  await proxy.stop();
+});
+
+export default tap.start();

test/test.socket-handler.simple.ts

@@ -0,0 +1,59 @@
+import { expect, tap } from '@git.zone/tstest/tapbundle';
+import * as net from 'net';
+import { SmartProxy } from '../ts/index.js';
+
+tap.test('simple socket handler test', async () => {
+  const proxy = new SmartProxy({
+    routes: [{
+      name: 'simple-handler',
+      match: { 
+        ports: 8888
+        // No domains restriction - will match all connections on this port
+      },
+      action: {
+        type: 'socket-handler',
+        socketHandler: (socket) => {
+          console.log('Handler called!');
+          socket.write('HELLO\n');
+          socket.end();
+        }
+      }
+    }],
+    enableDetailedLogging: true
+  });
+  
+  await proxy.start();
+  
+  // Test connection
+  const client = new net.Socket();
+  let response = '';
+  
+  client.on('data', (data) => {
+    response += data.toString();
+  });
+  
+  await new Promise<void>((resolve, reject) => {
+    client.connect(8888, 'localhost', () => {
+      console.log('Connected');
+      // Send some initial data to trigger the handler
+      client.write('test\n');
+      resolve();
+    });
+    client.on('error', reject);
+  });
+  
+  // Wait for response
+  await new Promise(resolve => {
+    client.on('close', () => {
+      console.log('Connection closed');
+      resolve(undefined);
+    });
+  });
+  
+  console.log('Got response:', response);
+  expect(response).toEqual('HELLO\n');
+  
+  await proxy.stop();
+});
+
+export default tap.start();

test/test.socket-handler.ts

@@ -0,0 +1,173 @@
+import { expect, tap } from '@git.zone/tstest/tapbundle';
+import * as net from 'net';
+import { SmartProxy } from '../ts/index.js';
+import type { IRouteConfig } from '../ts/index.js';
+
+let proxy: SmartProxy;
+
+tap.test('setup socket handler test', async () => {
+  // Create a simple socket handler route
+  const routes: IRouteConfig[] = [{
+    name: 'echo-handler',
+    match: { 
+      ports: 9999
+      // No domains restriction - matches all connections
+    },
+    action: {
+      type: 'socket-handler',
+      socketHandler: (socket) => {
+        console.log('Socket handler called');
+        // Simple echo server
+        socket.write('ECHO SERVER\n');
+        socket.on('data', (data) => {
+          console.log('Socket handler received data:', data.toString());
+          socket.write(`ECHO: ${data}`);
+        });
+        socket.on('error', (err) => {
+          console.error('Socket error:', err);
+        });
+      }
+    }
+  }];
+  
+  proxy = new SmartProxy({
+    routes,
+    enableDetailedLogging: false
+  });
+  
+  await proxy.start();
+});
+
+tap.test('should handle socket with custom function', async () => {
+  const client = new net.Socket();
+  let response = '';
+  
+  await new Promise<void>((resolve, reject) => {
+    client.connect(9999, 'localhost', () => {
+      console.log('Client connected to proxy');
+      resolve();
+    });
+    
+    client.on('error', reject);
+  });
+  
+  // Collect data
+  client.on('data', (data) => {
+    console.log('Client received:', data.toString());
+    response += data.toString();
+  });
+  
+  // Wait a bit for connection to stabilize
+  await new Promise(resolve => setTimeout(resolve, 50));
+  
+  // Send test data
+  console.log('Sending test data...');
+  client.write('Hello World\n');
+  
+  // Wait for response
+  await new Promise(resolve => setTimeout(resolve, 200));
+  
+  console.log('Total response:', response);
+  expect(response).toContain('ECHO SERVER');
+  expect(response).toContain('ECHO: Hello World');
+  
+  client.destroy();
+});
+
+tap.test('should handle async socket handler', async () => {
+  // Update route with async handler
+  await proxy.updateRoutes([{
+    name: 'async-handler',
+    match: { ports: 9999 },
+    action: {
+      type: 'socket-handler',
+      socketHandler: async (socket) => {
+        // Set up data handler first
+        socket.on('data', async (data) => {
+          console.log('Async handler received:', data.toString());
+          // Simulate async processing
+          await new Promise(resolve => setTimeout(resolve, 10));
+          const processed = `PROCESSED: ${data.toString().trim().toUpperCase()}\n`;
+          console.log('Sending:', processed);
+          socket.write(processed);
+        });
+        
+        // Then simulate async operation
+        await new Promise(resolve => setTimeout(resolve, 10));
+        socket.write('ASYNC READY\n');
+      }
+    }
+  }]);
+  
+  const client = new net.Socket();
+  let response = '';
+  
+  // Collect data
+  client.on('data', (data) => {
+    response += data.toString();
+  });
+  
+  await new Promise<void>((resolve, reject) => {
+    client.connect(9999, 'localhost', () => {
+      // Send initial data to trigger the handler
+      client.write('test data\n');
+      resolve();
+    });
+    
+    client.on('error', reject);
+  });
+  
+  // Wait for async processing
+  await new Promise(resolve => setTimeout(resolve, 200));
+  
+  console.log('Final response:', response);
+  expect(response).toContain('ASYNC READY');
+  expect(response).toContain('PROCESSED: TEST DATA');
+  
+  client.destroy();
+});
+
+tap.test('should handle errors in socket handler', async () => {
+  // Update route with error-throwing handler
+  await proxy.updateRoutes([{
+    name: 'error-handler',
+    match: { ports: 9999 },
+    action: {
+      type: 'socket-handler',
+      socketHandler: (socket) => {
+        throw new Error('Handler error');
+      }
+    }
+  }]);
+  
+  const client = new net.Socket();
+  let connectionClosed = false;
+  
+  client.on('close', () => {
+    connectionClosed = true;
+  });
+  
+  await new Promise<void>((resolve, reject) => {
+    client.connect(9999, 'localhost', () => {
+      // Connection established - send data to trigger handler
+      client.write('trigger\n');
+      resolve();
+    });
+    
+    client.on('error', () => {
+      // Ignore client errors - we expect the connection to be closed
+    });
+  });
+  
+  // Wait a bit
+  await new Promise(resolve => setTimeout(resolve, 100));
+  
+  // Socket should be closed due to handler error
+  expect(connectionClosed).toEqual(true);
+});
+
+tap.test('cleanup', async () => {
+  await proxy.stop();
+});
+
+export default tap.start();