dcrouter/test/suite/smtpclient_commands/test.ccmd-09.noop-command.ts

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

let testServer: any;

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

tap.test('CCMD-09: Basic NOOP command', async () => {
  const smtpClient = createSmtpClient({
    host: testServer.hostname,
    port: testServer.port,
    secure: false,
    connectionTimeout: 5000,
    debug: true
  });

  await smtpClient.connect();
  await smtpClient.sendCommand('EHLO testclient.example.com');

  // Send NOOP command
  const noopResponse = await smtpClient.sendCommand('NOOP');
  
  // Verify response
  expect(noopResponse).toInclude('250');
  console.log(`NOOP response: ${noopResponse.trim()}`);

  await smtpClient.close();
});

tap.test('CCMD-09: NOOP during transaction', async () => {
  const smtpClient = createSmtpClient({
    host: testServer.hostname,
    port: testServer.port,
    secure: false,
    connectionTimeout: 5000,
    debug: true
  });

  await smtpClient.connect();
  await smtpClient.sendCommand('EHLO testclient.example.com');

  // Start a transaction
  await smtpClient.sendCommand('MAIL FROM:<sender@example.com>');
  await smtpClient.sendCommand('RCPT TO:<recipient@example.com>');

  // Send NOOP - should not affect transaction
  const noopResponse = await smtpClient.sendCommand('NOOP');
  expect(noopResponse).toInclude('250');

  // Continue transaction - should still work
  const dataResponse = await smtpClient.sendCommand('DATA');
  expect(dataResponse).toInclude('354');

  // Send message
  const messageResponse = await smtpClient.sendCommand('Subject: Test\r\n\r\nTest message\r\n.');
  expect(messageResponse).toInclude('250');

  console.log('Transaction completed successfully after NOOP');

  await smtpClient.close();
});

tap.test('CCMD-09: Multiple NOOP commands', async () => {
  const smtpClient = createSmtpClient({
    host: testServer.hostname,
    port: testServer.port,
    secure: false,
    connectionTimeout: 5000,
    debug: true
  });

  await smtpClient.connect();
  await smtpClient.sendCommand('EHLO testclient.example.com');

  // Send multiple NOOPs rapidly
  const noopCount = 10;
  const responses: string[] = [];

  console.log(`Sending ${noopCount} NOOP commands...`);
  
  for (let i = 0; i < noopCount; i++) {
    const response = await smtpClient.sendCommand('NOOP');
    responses.push(response);
  }

  // All should succeed
  responses.forEach((response, index) => {
    expect(response).toInclude('250');
  });

  console.log(`All ${noopCount} NOOP commands succeeded`);

  await smtpClient.close();
});

tap.test('CCMD-09: NOOP for keep-alive', async () => {
  const smtpClient = createSmtpClient({
    host: testServer.hostname,
    port: testServer.port,
    secure: false,
    connectionTimeout: 10000,
    debug: true
  });

  await smtpClient.connect();
  await smtpClient.sendCommand('EHLO testclient.example.com');

  console.log('Using NOOP for keep-alive over 10 seconds...');

  // Send NOOP every 2 seconds for 10 seconds
  const keepAliveInterval = 2000;
  const duration = 10000;
  const iterations = duration / keepAliveInterval;

  for (let i = 0; i < iterations; i++) {
    await new Promise(resolve => setTimeout(resolve, keepAliveInterval));
    
    const startTime = Date.now();
    const response = await smtpClient.sendCommand('NOOP');
    const elapsed = Date.now() - startTime;
    
    expect(response).toInclude('250');
    console.log(`Keep-alive NOOP ${i + 1}: ${elapsed}ms`);
  }

  // Connection should still be active
  expect(smtpClient.isConnected()).toBeTruthy();

  await smtpClient.close();
});

tap.test('CCMD-09: NOOP with parameters', async () => {
  const smtpClient = createSmtpClient({
    host: testServer.hostname,
    port: testServer.port,
    secure: false,
    connectionTimeout: 5000,
    debug: true
  });

  await smtpClient.connect();
  await smtpClient.sendCommand('EHLO testclient.example.com');

  // RFC 5321 allows NOOP to have parameters (which are ignored)
  const noopVariants = [
    'NOOP',
    'NOOP test',
    'NOOP hello world',
    'NOOP 12345',
    'NOOP check connection'
  ];

  for (const command of noopVariants) {
    const response = await smtpClient.sendCommand(command);
    expect(response).toInclude('250');
    console.log(`"${command}" -> ${response.trim()}`);
  }

  await smtpClient.close();
});

tap.test('CCMD-09: NOOP timing analysis', async () => {
  const smtpClient = createSmtpClient({
    host: testServer.hostname,
    port: testServer.port,
    secure: false,
    connectionTimeout: 5000,
    debug: false // Quiet for timing
  });

  await smtpClient.connect();
  await smtpClient.sendCommand('EHLO testclient.example.com');

  // Measure NOOP response times
  const measurements = 20;
  const times: number[] = [];

  for (let i = 0; i < measurements; i++) {
    const startTime = Date.now();
    await smtpClient.sendCommand('NOOP');
    const elapsed = Date.now() - startTime;
    times.push(elapsed);
  }

  // Calculate statistics
  const avgTime = times.reduce((a, b) => a + b, 0) / times.length;
  const minTime = Math.min(...times);
  const maxTime = Math.max(...times);
  
  // Calculate standard deviation
  const variance = times.reduce((sum, time) => sum + Math.pow(time - avgTime, 2), 0) / times.length;
  const stdDev = Math.sqrt(variance);

  console.log(`NOOP timing analysis (${measurements} samples):`);
  console.log(`  Average: ${avgTime.toFixed(2)}ms`);
  console.log(`  Min: ${minTime}ms`);
  console.log(`  Max: ${maxTime}ms`);
  console.log(`  Std Dev: ${stdDev.toFixed(2)}ms`);

  // NOOP should be very fast
  expect(avgTime).toBeLessThan(50);
  
  // Check for consistency (low standard deviation)
  expect(stdDev).toBeLessThan(avgTime * 0.5); // Less than 50% of average

  await smtpClient.close();
});

tap.test('CCMD-09: NOOP during DATA phase', async () => {
  const smtpClient = createSmtpClient({
    host: testServer.hostname,
    port: testServer.port,
    secure: false,
    connectionTimeout: 5000,
    debug: true
  });

  await smtpClient.connect();
  await smtpClient.sendCommand('EHLO testclient.example.com');

  // Setup transaction
  await smtpClient.sendCommand('MAIL FROM:<sender@example.com>');
  await smtpClient.sendCommand('RCPT TO:<recipient@example.com>');
  
  // Enter DATA phase
  const dataResponse = await smtpClient.sendCommand('DATA');
  expect(dataResponse).toInclude('354');

  // During DATA phase, NOOP will be treated as message content
  await smtpClient.sendCommand('Subject: Test with NOOP');
  await smtpClient.sendCommand('');
  await smtpClient.sendCommand('This message contains the word NOOP');
  await smtpClient.sendCommand('NOOP'); // This is message content, not a command
  await smtpClient.sendCommand('End of message');
  
  // End DATA phase
  const endResponse = await smtpClient.sendCommand('.');
  expect(endResponse).toInclude('250');

  // Now NOOP should work as a command again
  const noopResponse = await smtpClient.sendCommand('NOOP');
  expect(noopResponse).toInclude('250');

  console.log('NOOP works correctly after DATA phase');

  await smtpClient.close();
});

tap.test('CCMD-09: NOOP in pipelined commands', async () => {
  const smtpClient = createSmtpClient({
    host: testServer.hostname,
    port: testServer.port,
    secure: false,
    enablePipelining: true,
    connectionTimeout: 5000,
    debug: true
  });

  await smtpClient.connect();
  await smtpClient.sendCommand('EHLO testclient.example.com');

  // Pipeline NOOP with other commands
  console.log('Pipelining NOOP with other commands...');
  
  const pipelinedCommands = [
    smtpClient.sendCommand('NOOP'),
    smtpClient.sendCommand('MAIL FROM:<sender@example.com>'),
    smtpClient.sendCommand('NOOP'),
    smtpClient.sendCommand('RCPT TO:<recipient@example.com>'),
    smtpClient.sendCommand('NOOP'),
    smtpClient.sendCommand('RSET'),
    smtpClient.sendCommand('NOOP')
  ];

  const responses = await Promise.all(pipelinedCommands);

  // All commands should succeed
  responses.forEach((response, index) => {
    expect(response).toInclude('250');
  });

  console.log('All pipelined commands including NOOPs succeeded');

  await smtpClient.close();
});

tap.test('CCMD-09: NOOP error scenarios', async () => {
  const smtpClient = createSmtpClient({
    host: testServer.hostname,
    port: testServer.port,
    secure: false,
    connectionTimeout: 5000,
    debug: true
  });

  await smtpClient.connect();
  
  // Try NOOP before EHLO/HELO (some servers might reject)
  const earlyNoop = await smtpClient.sendCommand('NOOP');
  console.log(`NOOP before EHLO: ${earlyNoop.trim()}`);
  
  // Most servers allow it, but check response
  expect(earlyNoop).toMatch(/[25]\d\d/);

  // Now do proper handshake
  await smtpClient.sendCommand('EHLO testclient.example.com');

  // Test malformed NOOP (though it should be accepted)
  const malformedTests = [
    'NOOP\t\ttabs',
    'NOOP  multiple  spaces',
    'noop lowercase',
    'NoOp MixedCase'
  ];

  for (const command of malformedTests) {
    try {
      const response = await smtpClient.sendCommand(command);
      console.log(`"${command}" -> ${response.trim()}`);
      // Most servers are lenient
    } catch (error) {
      console.log(`"${command}" -> Error: ${error.message}`);
    }
  }

  await smtpClient.close();
});

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

export default tap.start();