dcrouter/test/suite/error-handling/test.invalid-sequence.ts

import { tap, expect } from '@git.zone/tstest/tapbundle';
import * as net from 'net';
import * as path from 'path';
import { startTestServer, stopTestServer } from '../../helpers/server.loader.js';
import type { ITestServer } from '../../helpers/server.loader.js';

// Test configuration
const TEST_PORT = 30051;
const TEST_TIMEOUT = 10000;

let testServer: ITestServer;

// Setup
tap.test('setup - start SMTP server', async () => {
  testServer = await startTestServer({
    port: TEST_PORT,
    tlsEnabled: false,
    hostname: 'localhost'
  });
  
  expect(testServer).toBeDefined();
  expect(testServer.port).toEqual(TEST_PORT);
});

// Test: MAIL FROM before EHLO/HELO
tap.test('Invalid Sequence - should reject MAIL FROM before EHLO', async (tools) => {
  const done = tools.defer();
  
  const socket = net.createConnection({
    host: 'localhost',
    port: TEST_PORT,
    timeout: TEST_TIMEOUT
  });
  
  let receivedData = '';
  let currentStep = 'connecting';
  
  socket.on('data', (data) => {
    receivedData += data.toString();
    
    if (currentStep === 'connecting' && receivedData.includes('220')) {
      currentStep = 'mail_from_without_ehlo';
      socket.write('MAIL FROM:<test@example.com>\r\n');
    } else if (currentStep === 'mail_from_without_ehlo' && receivedData.includes('503')) {
      socket.write('QUIT\r\n');
      setTimeout(() => {
        socket.destroy();
        expect(receivedData).toInclude('503'); // Bad sequence of commands
        done.resolve();
      }, 100);
    }
  });
  
  socket.on('error', (error) => {
    done.reject(error);
  });
  
  socket.on('timeout', () => {
    socket.destroy();
    done.reject(new Error(`Connection timeout at step: ${currentStep}`));
  });
  
  await done.promise;
});

// Test: RCPT TO before MAIL FROM
tap.test('Invalid Sequence - should reject RCPT TO before MAIL FROM', async (tools) => {
  const done = tools.defer();
  
  const socket = net.createConnection({
    host: 'localhost',
    port: TEST_PORT,
    timeout: TEST_TIMEOUT
  });
  
  let receivedData = '';
  let currentStep = 'connecting';
  
  socket.on('data', (data) => {
    receivedData += data.toString();
    
    if (currentStep === 'connecting' && receivedData.includes('220')) {
      currentStep = 'ehlo';
      socket.write('EHLO test.example.com\r\n');
    } else if (currentStep === 'ehlo' && receivedData.includes('250')) {
      currentStep = 'rcpt_without_mail';
      socket.write('RCPT TO:<test@example.com>\r\n');
    } else if (currentStep === 'rcpt_without_mail' && receivedData.includes('503')) {
      socket.write('QUIT\r\n');
      setTimeout(() => {
        socket.destroy();
        expect(receivedData).toInclude('503');
        done.resolve();
      }, 100);
    }
  });
  
  socket.on('error', (error) => {
    done.reject(error);
  });
  
  socket.on('timeout', () => {
    socket.destroy();
    done.reject(new Error(`Connection timeout at step: ${currentStep}`));
  });
  
  await done.promise;
});

// Test: DATA before RCPT TO
tap.test('Invalid Sequence - should reject DATA before RCPT TO', async (tools) => {
  const done = tools.defer();
  
  const socket = net.createConnection({
    host: 'localhost',
    port: TEST_PORT,
    timeout: TEST_TIMEOUT
  });
  
  let receivedData = '';
  let currentStep = 'connecting';
  
  socket.on('data', (data) => {
    receivedData += data.toString();
    
    if (currentStep === 'connecting' && receivedData.includes('220')) {
      currentStep = 'ehlo';
      socket.write('EHLO test.example.com\r\n');
    } else if (currentStep === 'ehlo' && receivedData.includes('250')) {
      currentStep = 'mail_from';
      socket.write('MAIL FROM:<test@example.com>\r\n');
    } else if (currentStep === 'mail_from' && receivedData.includes('250')) {
      currentStep = 'data_without_rcpt';
      socket.write('DATA\r\n');
    } else if (currentStep === 'data_without_rcpt' && receivedData.includes('503')) {
      socket.write('QUIT\r\n');
      setTimeout(() => {
        socket.destroy();
        expect(receivedData).toInclude('503');
        done.resolve();
      }, 100);
    }
  });
  
  socket.on('error', (error) => {
    done.reject(error);
  });
  
  socket.on('timeout', () => {
    socket.destroy();
    done.reject(new Error(`Connection timeout at step: ${currentStep}`));
  });
  
  await done.promise;
});

// Test: Multiple EHLO commands (should be allowed)
tap.test('Invalid Sequence - should allow multiple EHLO commands', async (tools) => {
  const done = tools.defer();
  
  const socket = net.createConnection({
    host: 'localhost',
    port: TEST_PORT,
    timeout: TEST_TIMEOUT
  });
  
  let receivedData = '';
  let currentStep = 'connecting';
  let ehloCount = 0;
  
  socket.on('data', (data) => {
    receivedData += data.toString();
    
    if (currentStep === 'connecting' && receivedData.includes('220')) {
      currentStep = 'first_ehlo';
      socket.write('EHLO test1.example.com\r\n');
    } else if (currentStep === 'first_ehlo' && receivedData.includes('250')) {
      ehloCount++;
      currentStep = 'second_ehlo';
      receivedData = ''; // Clear buffer
      socket.write('EHLO test2.example.com\r\n');
    } else if (currentStep === 'second_ehlo' && receivedData.includes('250')) {
      ehloCount++;
      currentStep = 'third_ehlo';
      receivedData = ''; // Clear buffer
      socket.write('EHLO test3.example.com\r\n');
    } else if (currentStep === 'third_ehlo' && receivedData.includes('250')) {
      ehloCount++;
      socket.write('QUIT\r\n');
      setTimeout(() => {
        socket.destroy();
        expect(ehloCount).toEqual(3); // All EHLO commands should succeed
        done.resolve();
      }, 100);
    }
  });
  
  socket.on('error', (error) => {
    done.reject(error);
  });
  
  socket.on('timeout', () => {
    socket.destroy();
    done.reject(new Error(`Connection timeout at step: ${currentStep}`));
  });
  
  await done.promise;
});

// Test: Multiple MAIL FROM without RSET
tap.test('Invalid Sequence - should reject second MAIL FROM without RSET', async (tools) => {
  const done = tools.defer();
  
  const socket = net.createConnection({
    host: 'localhost',
    port: TEST_PORT,
    timeout: TEST_TIMEOUT
  });
  
  let receivedData = '';
  let currentStep = 'connecting';
  
  socket.on('data', (data) => {
    receivedData += data.toString();
    
    if (currentStep === 'connecting' && receivedData.includes('220')) {
      currentStep = 'ehlo';
      socket.write('EHLO test.example.com\r\n');
    } else if (currentStep === 'ehlo' && receivedData.includes('250')) {
      currentStep = 'first_mail_from';
      socket.write('MAIL FROM:<sender1@example.com>\r\n');
    } else if (currentStep === 'first_mail_from' && receivedData.includes('250')) {
      currentStep = 'second_mail_from';
      socket.write('MAIL FROM:<sender2@example.com>\r\n');
    } else if (currentStep === 'second_mail_from' && receivedData.includes('503')) {
      socket.write('QUIT\r\n');
      setTimeout(() => {
        socket.destroy();
        expect(receivedData).toInclude('503');
        done.resolve();
      }, 100);
    }
  });
  
  socket.on('error', (error) => {
    done.reject(error);
  });
  
  socket.on('timeout', () => {
    socket.destroy();
    done.reject(new Error(`Connection timeout at step: ${currentStep}`));
  });
  
  await done.promise;
});

// Test: DATA without MAIL FROM
tap.test('Invalid Sequence - should reject DATA without MAIL FROM', async (tools) => {
  const done = tools.defer();
  
  const socket = net.createConnection({
    host: 'localhost',
    port: TEST_PORT,
    timeout: TEST_TIMEOUT
  });
  
  let receivedData = '';
  let currentStep = 'connecting';
  
  socket.on('data', (data) => {
    receivedData += data.toString();
    
    if (currentStep === 'connecting' && receivedData.includes('220')) {
      currentStep = 'ehlo';
      socket.write('EHLO test.example.com\r\n');
    } else if (currentStep === 'ehlo' && receivedData.includes('250')) {
      currentStep = 'data_without_mail';
      socket.write('DATA\r\n');
    } else if (currentStep === 'data_without_mail' && receivedData.includes('503')) {
      socket.write('QUIT\r\n');
      setTimeout(() => {
        socket.destroy();
        expect(receivedData).toInclude('503');
        done.resolve();
      }, 100);
    }
  });
  
  socket.on('error', (error) => {
    done.reject(error);
  });
  
  socket.on('timeout', () => {
    socket.destroy();
    done.reject(new Error(`Connection timeout at step: ${currentStep}`));
  });
  
  await done.promise;
});

// Test: Commands after QUIT
tap.test('Invalid Sequence - should reject commands after QUIT', async (tools) => {
  const done = tools.defer();
  
  const socket = net.createConnection({
    host: 'localhost',
    port: TEST_PORT,
    timeout: TEST_TIMEOUT
  });
  
  let receivedData = '';
  let currentStep = 'connecting';
  let quitResponseReceived = false;
  
  socket.on('data', (data) => {
    receivedData += data.toString();
    
    if (currentStep === 'connecting' && receivedData.includes('220')) {
      currentStep = 'ehlo';
      socket.write('EHLO test.example.com\r\n');
    } else if (currentStep === 'ehlo' && receivedData.includes('250')) {
      currentStep = 'quit';
      socket.write('QUIT\r\n');
    } else if (currentStep === 'quit' && receivedData.includes('221')) {
      quitResponseReceived = true;
      // Try to send command after QUIT
      try {
        socket.write('EHLO test.example.com\r\n');
        // If write succeeds, wait to see if we get a response
        setTimeout(() => {
          socket.destroy();
          done.resolve(); // No response expected after QUIT
        }, 1000);
      } catch (err) {
        // Write failed - connection already closed
        done.resolve();
      }
    }
  });
  
  socket.on('close', () => {
    if (quitResponseReceived) {
      done.resolve();
    }
  });
  
  socket.on('error', (error) => {
    if (quitResponseReceived && error.message.includes('EPIPE')) {
      done.resolve();
    } else {
      done.reject(error);
    }
  });
  
  socket.on('timeout', () => {
    socket.destroy();
    done.reject(new Error(`Connection timeout at step: ${currentStep}`));
  });
  
  await done.promise;
});

// Test: RCPT TO without proper email brackets
tap.test('Invalid Sequence - should handle commands with wrong syntax in sequence', async (tools) => {
  const done = tools.defer();
  
  const socket = net.createConnection({
    host: 'localhost',
    port: TEST_PORT,
    timeout: TEST_TIMEOUT
  });
  
  let receivedData = '';
  let currentStep = 'connecting';
  
  socket.on('data', (data) => {
    receivedData += data.toString();
    
    if (currentStep === 'connecting' && receivedData.includes('220')) {
      currentStep = 'ehlo';
      socket.write('EHLO test.example.com\r\n');
    } else if (currentStep === 'ehlo' && receivedData.includes('250')) {
      currentStep = 'mail_from';
      socket.write('MAIL FROM:<sender@example.com>\r\n');
    } else if (currentStep === 'mail_from' && receivedData.includes('250')) {
      currentStep = 'bad_rcpt';
      // RCPT TO with wrong syntax
      socket.write('RCPT TO:recipient@example.com\r\n'); // Missing brackets
    } else if (currentStep === 'bad_rcpt' && receivedData.includes('501')) {
      // After syntax error, try valid command
      currentStep = 'valid_rcpt';
      socket.write('RCPT TO:<recipient@example.com>\r\n');
    } else if (currentStep === 'valid_rcpt' && receivedData.includes('250')) {
      socket.write('QUIT\r\n');
      setTimeout(() => {
        socket.destroy();
        expect(receivedData).toInclude('501'); // Syntax error
        expect(receivedData).toInclude('250'); // Valid command worked
        done.resolve();
      }, 100);
    }
  });
  
  socket.on('error', (error) => {
    done.reject(error);
  });
  
  socket.on('timeout', () => {
    socket.destroy();
    done.reject(new Error(`Connection timeout at step: ${currentStep}`));
  });
  
  await done.promise;
});

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

// Start the test
tap.start();