dcrouter/test/suite/smtpclient_connection/test.ccm-09.ipv6-dual-stack.ts

import { tap, expect } from '@git.zone/tstest/tapbundle';
import { startTestSmtpServer } from '../../helpers/server.loader.js';
import { createSmtpClient } from '../../helpers/smtp.client.js';
import * as net from 'net';
import * as os from 'os';

let testServer: any;

tap.test('setup test SMTP server', async () => {
  testServer = await startTestSmtpServer();
  expect(testServer).toBeTruthy();
  expect(testServer.port).toBeGreaterThan(0);
});

tap.test('CCM-09: Check system IPv6 support', async () => {
  const networkInterfaces = os.networkInterfaces();
  let hasIPv6 = false;
  
  for (const interfaceName in networkInterfaces) {
    const interfaces = networkInterfaces[interfaceName];
    if (interfaces) {
      for (const iface of interfaces) {
        if (iface.family === 'IPv6' && !iface.internal) {
          hasIPv6 = true;
          console.log(`Found IPv6 address: ${iface.address} on ${interfaceName}`);
        }
      }
    }
  }
  
  console.log(`System has IPv6 support: ${hasIPv6}`);
});

tap.test('CCM-09: IPv4 connection test', async () => {
  const smtpClient = createSmtpClient({
    host: '127.0.0.1', // Explicit IPv4
    port: testServer.port,
    secure: false,
    connectionTimeout: 5000,
    debug: true
  });

  let connected = false;
  let connectionFamily = '';

  smtpClient.on('connection', (info: any) => {
    connected = true;
    if (info && info.socket) {
      connectionFamily = info.socket.remoteFamily || '';
    }
  });

  smtpClient.on('error', (error: Error) => {
    console.error('IPv4 connection error:', error.message);
  });

  // Test connection
  const result = await smtpClient.connect();
  expect(result).toBeTruthy();
  expect(smtpClient.isConnected()).toBeTruthy();
  
  console.log(`Connected via IPv4, family: ${connectionFamily}`);
  
  await smtpClient.close();
});

tap.test('CCM-09: IPv6 connection test (if supported)', async () => {
  // Check if IPv6 is available
  const hasIPv6 = await new Promise<boolean>((resolve) => {
    const testSocket = net.createConnection({
      host: '::1',
      port: 1, // Any port, will fail but tells us if IPv6 works
      timeout: 100
    });
    
    testSocket.on('error', (err: any) => {
      // ECONNREFUSED means IPv6 works but port is closed (expected)
      // ENETUNREACH or EAFNOSUPPORT means IPv6 not available
      resolve(err.code === 'ECONNREFUSED');
    });
    
    testSocket.on('connect', () => {
      testSocket.end();
      resolve(true);
    });
  });

  if (!hasIPv6) {
    console.log('IPv6 not available on this system, skipping IPv6 tests');
    return;
  }

  // Try IPv6 connection
  const smtpClient = createSmtpClient({
    host: '::1', // IPv6 loopback
    port: testServer.port,
    secure: false,
    connectionTimeout: 5000,
    debug: true
  });

  let connected = false;
  let connectionFamily = '';

  smtpClient.on('connection', (info: any) => {
    connected = true;
    if (info && info.socket) {
      connectionFamily = info.socket.remoteFamily || '';
    }
  });

  smtpClient.on('error', (error: Error) => {
    console.error('IPv6 connection error:', error.message);
  });

  try {
    const result = await smtpClient.connect();
    if (result && smtpClient.isConnected()) {
      console.log(`Connected via IPv6, family: ${connectionFamily}`);
      await smtpClient.close();
    }
  } catch (error) {
    console.log('IPv6 connection failed (server may not support IPv6):', error.message);
  }
});

tap.test('CCM-09: Hostname resolution preference', async () => {
  // Test that client can handle hostnames that resolve to both IPv4 and IPv6
  const smtpClient = createSmtpClient({
    host: 'localhost', // Should resolve to both 127.0.0.1 and ::1
    port: testServer.port,
    secure: false,
    connectionTimeout: 5000,
    debug: true
  });

  let connectionInfo: any = null;

  smtpClient.on('connection', (info: any) => {
    connectionInfo = info;
  });

  const result = await smtpClient.connect();
  expect(result).toBeTruthy();
  expect(smtpClient.isConnected()).toBeTruthy();

  if (connectionInfo && connectionInfo.socket) {
    console.log(`Connected to localhost via ${connectionInfo.socket.remoteFamily || 'unknown'}`);
    console.log(`Local address: ${connectionInfo.socket.localAddress}`);
    console.log(`Remote address: ${connectionInfo.socket.remoteAddress}`);
  }

  await smtpClient.close();
});

tap.test('CCM-09: Happy Eyeballs algorithm simulation', async () => {
  // Test connecting to multiple addresses with preference
  const addresses = ['127.0.0.1', '::1', 'localhost'];
  const results: Array<{ address: string; time: number; success: boolean }> = [];

  for (const address of addresses) {
    const startTime = Date.now();
    const smtpClient = createSmtpClient({
      host: address,
      port: testServer.port,
      secure: false,
      connectionTimeout: 1000,
      debug: false
    });

    try {
      const connected = await smtpClient.connect();
      const elapsed = Date.now() - startTime;
      results.push({ address, time: elapsed, success: !!connected });
      
      if (connected) {
        await smtpClient.close();
      }
    } catch (error) {
      const elapsed = Date.now() - startTime;
      results.push({ address, time: elapsed, success: false });
    }
  }

  console.log('Connection race results:');
  results.forEach(r => {
    console.log(`  ${r.address}: ${r.success ? 'SUCCESS' : 'FAILED'} in ${r.time}ms`);
  });

  // At least one should succeed
  const successfulConnections = results.filter(r => r.success);
  expect(successfulConnections.length).toBeGreaterThan(0);
});

tap.test('cleanup test SMTP server', async () => {
  if (testServer) {
    await testServer.stop();
  }
});

export default tap.start();