mailer/test/suite/smtpserver_connection/test.cm-07.abrupt-disconnection.ts

import { tap, expect } from '@git.zone/tstest/tapbundle';
import * as net from 'net';
import { startTestServer, stopTestServer } from '../../helpers/server.loader.ts'
import type { ITestServer } from '../../helpers/server.loader.ts';
const TEST_PORT = 2525;
const TEST_TIMEOUT = 30000;

let testServer: ITestServer;

tap.test('setup - start SMTP server for abrupt disconnection tests', async () => {
  testServer = await startTestServer({ port: TEST_PORT });
  await new Promise(resolve => setTimeout(resolve, 1000));
});

tap.test('Abrupt Disconnection - should handle socket destruction without QUIT', async (tools) => {
  const done = tools.defer();
  
  try {
    const socket = net.createConnection({
      host: 'localhost',
      port: TEST_PORT,
      timeout: TEST_TIMEOUT
    });
    
    await new Promise<void>((resolve, reject) => {
      socket.once('connect', () => resolve());
      socket.once('error', reject);
    });
    
    // Get banner
    const banner = await new Promise<string>((resolve) => {
      socket.once('data', (chunk) => resolve(chunk.toString()));
    });
    
    expect(banner).toInclude('220');
    
    // Send EHLO
    socket.write('EHLO testhost\r\n');
    
    await new Promise<string>((resolve) => {
      let data = '';
      const handler = (chunk: Buffer) => {
        data += chunk.toString();
        if (data.includes('\r\n') && (data.match(/^250 /m) || data.match(/^250-.*\r\n250 /ms))) {
          socket.removeListener('data', handler);
          resolve(data);
        }
      };
      socket.on('data', handler);
    });
    
    // Abruptly disconnect without QUIT
    console.log('Destroying socket without QUIT...');
    socket.destroy();
    
    // Wait a moment for server to handle the disconnection
    await new Promise(resolve => setTimeout(resolve, 1000));
    
    // Test server recovery - try new connection
    console.log('Testing server recovery with new connection...');
    const recoverySocket = net.createConnection({
      host: 'localhost',
      port: TEST_PORT,
      timeout: TEST_TIMEOUT
    });
    
    const recoveryConnected = await new Promise<boolean>((resolve) => {
      recoverySocket.once('connect', () => resolve(true));
      recoverySocket.once('error', () => resolve(false));
      setTimeout(() => resolve(false), 5000);
    });
    
    expect(recoveryConnected).toEqual(true);
    
    if (recoveryConnected) {
      // Get banner from recovery connection
      const recoveryBanner = await new Promise<string>((resolve) => {
        recoverySocket.once('data', (chunk) => resolve(chunk.toString()));
      });
      
      expect(recoveryBanner).toInclude('220');
      console.log('Server recovered successfully, accepting new connections');
      
      // Clean up recovery connection properly
      recoverySocket.write('QUIT\r\n');
      recoverySocket.end();
    }
    
  } finally {
    done.resolve();
  }
});

tap.test('Abrupt Disconnection - should handle multiple simultaneous abrupt disconnections', async (tools) => {
  const done = tools.defer();
  
  try {
    const connections = 5;
    const sockets: net.Socket[] = [];
    
    // Create multiple connections
    for (let i = 0; i < connections; i++) {
      const socket = net.createConnection({
        host: 'localhost',
        port: TEST_PORT,
        timeout: TEST_TIMEOUT
      });
      
      await new Promise<void>((resolve, reject) => {
        socket.once('connect', () => resolve());
        socket.once('error', reject);
      });
      
      // Get banner
      await new Promise<void>((resolve) => {
        socket.once('data', () => resolve());
      });
      
      sockets.push(socket);
    }
    
    console.log(`Created ${connections} connections`);
    
    // Abruptly disconnect all at once
    console.log('Destroying all sockets simultaneously...');
    sockets.forEach(socket => socket.destroy());
    
    // Wait for server to handle disconnections
    await new Promise(resolve => setTimeout(resolve, 2000));
    
    // Test that server still accepts new connections
    console.log('Testing server stability after multiple abrupt disconnections...');
    const testSocket = net.createConnection({
      host: 'localhost',
      port: TEST_PORT,
      timeout: TEST_TIMEOUT
    });
    
    const stillAccepting = await new Promise<boolean>((resolve) => {
      testSocket.once('connect', () => resolve(true));
      testSocket.once('error', () => resolve(false));
      setTimeout(() => resolve(false), 5000);
    });
    
    expect(stillAccepting).toEqual(true);
    
    if (stillAccepting) {
      const banner = await new Promise<string>((resolve) => {
        testSocket.once('data', (chunk) => resolve(chunk.toString()));
      });
      
      expect(banner).toInclude('220');
      console.log('Server remained stable after multiple abrupt disconnections');
      
      testSocket.write('QUIT\r\n');
      testSocket.end();
    }
    
  } finally {
    done.resolve();
  }
});

tap.test('Abrupt Disconnection - should handle disconnection during DATA transfer', async (tools) => {
  const done = tools.defer();
  
  try {
    const socket = net.createConnection({
      host: 'localhost',
      port: TEST_PORT,
      timeout: TEST_TIMEOUT
    });
    
    await new Promise<void>((resolve, reject) => {
      socket.once('connect', () => resolve());
      socket.once('error', reject);
    });
    
    // Get banner
    await new Promise<string>((resolve) => {
      socket.once('data', (chunk) => resolve(chunk.toString()));
    });
    
    // Send EHLO
    socket.write('EHLO testhost\r\n');
    await new Promise<string>((resolve) => {
      let data = '';
      const handler = (chunk: Buffer) => {
        data += chunk.toString();
        if (data.includes('\r\n') && (data.match(/^250 /m) || data.match(/^250-.*\r\n250 /ms))) {
          socket.removeListener('data', handler);
          resolve(data);
        }
      };
      socket.on('data', handler);
    });
    
    // Send MAIL FROM
    socket.write('MAIL FROM:<sender@example.com>\r\n');
    await new Promise<string>((resolve) => {
      socket.once('data', (chunk) => resolve(chunk.toString()));
    });
    
    // Send RCPT TO
    socket.write('RCPT TO:<recipient@example.com>\r\n');
    await new Promise<string>((resolve) => {
      socket.once('data', (chunk) => resolve(chunk.toString()));
    });
    
    // Start DATA
    socket.write('DATA\r\n');
    const dataResponse = await new Promise<string>((resolve) => {
      socket.once('data', (chunk) => resolve(chunk.toString()));
    });
    
    expect(dataResponse).toInclude('354');
    
    // Send partial email data then disconnect abruptly
    socket.write('From: sender@example.com\r\n');
    socket.write('To: recipient@example.com\r\n');
    socket.write('Subject: Test ');
    
    console.log('Disconnecting during DATA transfer...');
    socket.destroy();
    
    // Wait for server to handle disconnection
    await new Promise(resolve => setTimeout(resolve, 1500));
    
    // Verify server can handle new connections
    const newSocket = net.createConnection({
      host: 'localhost',
      port: TEST_PORT,
      timeout: TEST_TIMEOUT
    });
    
    const canConnect = await new Promise<boolean>((resolve) => {
      newSocket.once('connect', () => resolve(true));
      newSocket.once('error', () => resolve(false));
      setTimeout(() => resolve(false), 5000);
    });
    
    expect(canConnect).toEqual(true);
    
    if (canConnect) {
      const banner = await new Promise<string>((resolve) => {
        newSocket.once('data', (chunk) => resolve(chunk.toString()));
      });
      
      expect(banner).toInclude('220');
      console.log('Server recovered from disconnection during DATA transfer');
      
      newSocket.write('QUIT\r\n');
      newSocket.end();
    }
    
  } finally {
    done.resolve();
  }
});

tap.test('Abrupt Disconnection - should timeout idle connections', async (tools) => {
  const done = tools.defer();
  
  try {
    const socket = net.createConnection({
      host: 'localhost',
      port: TEST_PORT,
      timeout: TEST_TIMEOUT
    });
    
    await new Promise<void>((resolve, reject) => {
      socket.once('connect', () => resolve());
      socket.once('error', reject);
    });
    
    // Get banner
    const banner = await new Promise<string>((resolve) => {
      socket.once('data', (chunk) => resolve(chunk.toString()));
    });
    
    expect(banner).toInclude('220');
    console.log('Connected, now testing idle timeout...');
    
    // Don't send any commands and wait for server to potentially timeout
    // Most servers have a timeout of 5-10 minutes, so we'll test shorter
    let disconnectedByServer = false;
    
    socket.on('close', () => {
      disconnectedByServer = true;
    });
    
    socket.on('end', () => {
      disconnectedByServer = true;
    });
    
    // Wait 10 seconds to see if server has a short idle timeout
    await new Promise(resolve => setTimeout(resolve, 10000));
    
    if (!disconnectedByServer) {
      console.log('Server maintains idle connections (no short timeout detected)');
      // Send QUIT to close gracefully
      socket.write('QUIT\r\n');
      socket.end();
    } else {
      console.log('Server disconnected idle connection');
    }
    
    // Either behavior is acceptable
    expect(true).toEqual(true);
    
  } finally {
    done.resolve();
  }
});

tap.test('cleanup - stop SMTP server', async () => {
  await stopTestServer(testServer);
  expect(true).toEqual(true);
});

export default tap.start();