dcrouter/test/suite/smtpclient_edge-cases/test.cedge-03.protocol-violations.ts

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

tap.test('CEDGE-03: should handle protocol violations gracefully', async (tools) => {
  const testId = 'CEDGE-03-protocol-violations';
  console.log(`\n${testId}: Testing protocol violation handling...`);

  let scenarioCount = 0;

  // Scenario 1: Server closes connection unexpectedly
  await (async () => {
    scenarioCount++;
    console.log(`\nScenario ${scenarioCount}: Testing unexpected connection closure`);
    
    const testServer = await createTestServer({
      onConnection: async (socket) => {
        console.log('  [Server] Client connected');
        socket.write('220 mail.example.com ESMTP\r\n');
        
        let commandCount = 0;
        socket.on('data', (data) => {
          commandCount++;
          const command = data.toString().trim();
          console.log(`  [Server] Received: ${command}`);
          
          if (command.startsWith('EHLO')) {
            socket.write('250-mail.example.com\r\n');
            socket.write('250 OK\r\n');
          } else if (command.startsWith('MAIL FROM:')) {
            // Abruptly close connection
            console.log('  [Server] Closing connection unexpectedly');
            socket.destroy();
          }
        });
      }
    });

    const smtpClient = createSmtpClient({
      host: testServer.hostname,
      port: testServer.port,
      secure: false
    });

    const email = new plugins.smartmail.Email({
      from: 'sender@example.com',
      to: ['recipient@example.com'],
      subject: 'Connection closure test',
      text: 'Testing unexpected disconnection'
    });

    try {
      await smtpClient.sendMail(email);
      console.log('  Unexpected success');
    } catch (error) {
      console.log(`  Expected error: ${error.message}`);
      expect(error).toBeDefined();
    }

    await testServer.server.close();
  })();

  // Scenario 2: Server sends data without CRLF
  await (async () => {
    scenarioCount++;
    console.log(`\nScenario ${scenarioCount}: Testing responses without proper CRLF`);
    
    const testServer = await createTestServer({
      onConnection: async (socket) => {
        console.log('  [Server] Client connected');
        // Send greeting without CRLF
        socket.write('220 mail.example.com ESMTP');
        // Then send proper CRLF
        setTimeout(() => socket.write('\r\n'), 100);
        
        socket.on('data', (data) => {
          const command = data.toString().trim();
          console.log(`  [Server] Received: ${command}`);
          
          if (command.startsWith('EHLO')) {
            // Mix responses with and without CRLF
            socket.write('250-mail.example.com\n');  // Just LF
            socket.write('250-SIZE 10485760\r');     // Just CR
            socket.write('250 OK\r\n');              // Proper CRLF
          } else if (command.startsWith('MAIL FROM:')) {
            socket.write('250 OK\r\n');
          } else if (command.startsWith('RCPT TO:')) {
            socket.write('250 OK\r\n');
          } else if (command === 'DATA') {
            socket.write('354 Start mail input\r\n');
          } else if (command === '.') {
            socket.write('250 OK\r\n');
          } else if (command === 'QUIT') {
            socket.write('221 Bye\r\n');
            socket.end();
          }
        });
      }
    });

    const smtpClient = createSmtpClient({
      host: testServer.hostname,
      port: testServer.port,
      secure: false
    });

    const email = new plugins.smartmail.Email({
      from: 'sender@example.com',
      to: ['recipient@example.com'],
      subject: 'Line ending test',
      text: 'Testing non-standard line endings'
    });

    const result = await smtpClient.sendMail(email);
    console.log(`  Result: ${result.messageId ? 'Success (handled gracefully)' : 'Failed'}`);
    expect(result).toBeDefined();

    await testServer.server.close();
  })();

  // Scenario 3: Server sends responses in wrong order
  await (async () => {
    scenarioCount++;
    console.log(`\nScenario ${scenarioCount}: Testing out-of-order responses`);
    
    const testServer = await createTestServer({
      onConnection: async (socket) => {
        console.log('  [Server] Client connected');
        socket.write('220 mail.example.com ESMTP\r\n');
        
        const pendingResponses: Array<() => void> = [];
        
        socket.on('data', (data) => {
          const command = data.toString().trim();
          console.log(`  [Server] Received: ${command}`);
          
          if (command.startsWith('EHLO')) {
            socket.write('250-mail.example.com\r\n');
            socket.write('250 OK\r\n');
          } else if (command.startsWith('MAIL FROM:')) {
            // Delay response
            pendingResponses.push(() => {
              socket.write('250 OK\r\n');
            });
          } else if (command.startsWith('RCPT TO:')) {
            // Send this response first, then the MAIL response
            socket.write('250 OK\r\n');
            if (pendingResponses.length > 0) {
              pendingResponses.forEach(fn => fn());
              pendingResponses.length = 0;
            }
          } else if (command === 'DATA') {
            socket.write('354 Start mail input\r\n');
          } else if (command === '.') {
            socket.write('250 OK\r\n');
          } else if (command === 'QUIT') {
            socket.write('221 Bye\r\n');
            socket.end();
          }
        });
      }
    });

    const smtpClient = createSmtpClient({
      host: testServer.hostname,
      port: testServer.port,
      secure: false
    });

    const email = new plugins.smartmail.Email({
      from: 'sender@example.com',
      to: ['recipient@example.com'],
      subject: 'Response order test',
      text: 'Testing out-of-order responses'
    });

    try {
      const result = await smtpClient.sendMail(email);
      console.log(`  Result: ${result.messageId ? 'Success' : 'Failed'}`);
    } catch (error) {
      console.log(`  Expected possible error: ${error.message}`);
      expect(error).toBeDefined();
    }

    await testServer.server.close();
  })();

  // Scenario 4: Server sends unsolicited responses
  await (async () => {
    scenarioCount++;
    console.log(`\nScenario ${scenarioCount}: Testing unsolicited server responses`);
    
    const testServer = await createTestServer({
      onConnection: async (socket) => {
        console.log('  [Server] Client connected');
        socket.write('220 mail.example.com ESMTP\r\n');
        
        // Send unsolicited responses periodically
        const interval = setInterval(() => {
          if (!socket.destroyed) {
            console.log('  [Server] Sending unsolicited response');
            socket.write('250-NOTICE: Server status update\r\n');
          }
        }, 500);
        
        socket.on('close', () => clearInterval(interval));
        
        socket.on('data', (data) => {
          const command = data.toString().trim();
          console.log(`  [Server] Received: ${command}`);
          
          if (command.startsWith('EHLO')) {
            socket.write('250-mail.example.com\r\n');
            socket.write('250 OK\r\n');
          } else if (command.startsWith('MAIL FROM:')) {
            socket.write('250 OK\r\n');
          } else if (command.startsWith('RCPT TO:')) {
            socket.write('250 OK\r\n');
          } else if (command === 'DATA') {
            socket.write('354 Start mail input\r\n');
          } else if (command === '.') {
            socket.write('250 OK\r\n');
          } else if (command === 'QUIT') {
            clearInterval(interval);
            socket.write('221 Bye\r\n');
            socket.end();
          }
        });
      }
    });

    const smtpClient = createSmtpClient({
      host: testServer.hostname,
      port: testServer.port,
      secure: false
    });

    const email = new plugins.smartmail.Email({
      from: 'sender@example.com',
      to: ['recipient@example.com'],
      subject: 'Unsolicited response test',
      text: 'Testing unsolicited server messages'
    });

    const result = await smtpClient.sendMail(email);
    console.log(`  Result: ${result.messageId ? 'Success' : 'Failed'}`);
    expect(result).toBeDefined();

    await testServer.server.close();
  })();

  // Scenario 5: Server violates response code format
  await (async () => {
    scenarioCount++;
    console.log(`\nScenario ${scenarioCount}: Testing invalid response codes`);
    
    const testServer = await createTestServer({
      onConnection: async (socket) => {
        console.log('  [Server] Client connected');
        // Invalid response code (should be 3 digits)
        socket.write('22 mail.example.com ESMTP\r\n');
        setTimeout(() => {
          // Send correct response
          socket.write('220 mail.example.com ESMTP\r\n');
        }, 100);
        
        socket.on('data', (data) => {
          const command = data.toString().trim();
          console.log(`  [Server] Received: ${command}`);
          
          if (command.startsWith('EHLO')) {
            // Mix valid and invalid response codes
            socket.write('250-mail.example.com\r\n');
            socket.write('25O-TYPO IN CODE\r\n');  // Letter O instead of zero
            socket.write('250 OK\r\n');
          } else if (command.startsWith('MAIL FROM:')) {
            socket.write('2.5.0 OK\r\n');  // Wrong format
            setTimeout(() => {
              socket.write('250 OK\r\n');
            }, 50);
          } else if (command.startsWith('RCPT TO:')) {
            socket.write('250 OK\r\n');
          } else if (command === 'DATA') {
            socket.write('354 Start mail input\r\n');
          } else if (command === '.') {
            socket.write('250 OK\r\n');
          } else if (command === 'QUIT') {
            socket.write('221 Bye\r\n');
            socket.end();
          }
        });
      }
    });

    const smtpClient = createSmtpClient({
      host: testServer.hostname,
      port: testServer.port,
      secure: false
    });

    const email = new plugins.smartmail.Email({
      from: 'sender@example.com',
      to: ['recipient@example.com'],
      subject: 'Response code test',
      text: 'Testing invalid response codes'
    });

    try {
      const result = await smtpClient.sendMail(email);
      console.log(`  Result: ${result.messageId ? 'Success (handled invalid codes)' : 'Failed'}`);
    } catch (error) {
      console.log(`  Expected possible error: ${error.message}`);
      expect(error).toBeDefined();
    }

    await testServer.server.close();
  })();

  // Scenario 6: Server sends binary data
  await (async () => {
    scenarioCount++;
    console.log(`\nScenario ${scenarioCount}: Testing binary data in responses`);
    
    const testServer = await createTestServer({
      onConnection: async (socket) => {
        console.log('  [Server] Client connected');
        // Send greeting with some binary data
        socket.write('220 mail.example.com ESMTP\r\n');
        socket.write(Buffer.from([0x00, 0x01, 0x02, 0x03]));  // Binary data
        
        socket.on('data', (data) => {
          const command = data.toString().trim();
          console.log(`  [Server] Received: ${command}`);
          
          if (command.startsWith('EHLO')) {
            socket.write('250-mail.example.com\r\n');
            socket.write('250 OK\r\n');
          } else if (command.startsWith('MAIL FROM:')) {
            socket.write('250 OK\r\n');
          } else if (command.startsWith('RCPT TO:')) {
            socket.write('250 OK\r\n');
          } else if (command === 'DATA') {
            socket.write('354 Start mail input\r\n');
          } else if (command === '.') {
            // Include binary in response
            socket.write('250 OK ');
            socket.write(Buffer.from([0xFF, 0xFE]));
            socket.write('\r\n');
          } else if (command === 'QUIT') {
            socket.write('221 Bye\r\n');
            socket.end();
          }
        });
      }
    });

    const smtpClient = createSmtpClient({
      host: testServer.hostname,
      port: testServer.port,
      secure: false
    });

    const email = new plugins.smartmail.Email({
      from: 'sender@example.com',
      to: ['recipient@example.com'],
      subject: 'Binary data test',
      text: 'Testing binary data handling'
    });

    try {
      const result = await smtpClient.sendMail(email);
      console.log(`  Result: ${result.messageId ? 'Success' : 'Failed'}`);
      expect(result).toBeDefined();
    } catch (error) {
      console.log(`  Error handling binary data: ${error.message}`);
      expect(error).toBeDefined();
    }

    await testServer.server.close();
  })();

  console.log(`\n${testId}: All ${scenarioCount} protocol violation scenarios tested ✓`);
});