mailer/test/suite/smtpserver_error-handling/test.err-02.invalid-sequence.test.ts

/**
 * ERR-02: Invalid Sequence Tests
 * Tests SMTP server handling of commands in incorrect sequence
 */

import { assert, assertMatch } from '@std/assert';
import { startTestServer, stopTestServer, type ITestServer } from '../../helpers/server.loader.ts';
import {
  connectToSmtp,
  waitForGreeting,
  sendSmtpCommand,
  readSmtpResponse,
  closeSmtpConnection,
} from '../../helpers/utils.ts';

const TEST_PORT = 25262;
let testServer: ITestServer;

Deno.test({
  name: 'ERR-02: Setup - Start SMTP server',
  async fn() {
    testServer = await startTestServer({ port: TEST_PORT });
    assert(testServer, 'Test server should be created');
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'ERR-02: Invalid Sequence - rejects MAIL FROM before EHLO',
  async fn() {
    const conn = await connectToSmtp('localhost', TEST_PORT);

    try {
      await waitForGreeting(conn);

      // Send MAIL FROM without EHLO
      const encoder = new TextEncoder();
      await conn.write(encoder.encode('MAIL FROM:<test@example.com>\r\n'));

      const response = await readSmtpResponse(conn);

      // Should return 503 (bad sequence of commands)
      assertMatch(response, /^503/, 'Should reject MAIL FROM before EHLO with 503');

      await sendSmtpCommand(conn, 'QUIT', '221');
      console.log('✓ MAIL FROM before EHLO rejected');
    } finally {
      try {
        conn.close();
      } catch {
        // Ignore
      }
    }
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'ERR-02: Invalid Sequence - rejects RCPT TO before MAIL FROM',
  async fn() {
    const conn = await connectToSmtp('localhost', TEST_PORT);

    try {
      await waitForGreeting(conn);
      await sendSmtpCommand(conn, 'EHLO test.example.com', '250');

      // Send RCPT TO without MAIL FROM
      const encoder = new TextEncoder();
      await conn.write(encoder.encode('RCPT TO:<test@example.com>\r\n'));

      const response = await readSmtpResponse(conn);

      // Should return 503 (bad sequence of commands)
      assertMatch(response, /^503/, 'Should reject RCPT TO before MAIL FROM with 503');

      await sendSmtpCommand(conn, 'QUIT', '221');
      console.log('✓ RCPT TO before MAIL FROM rejected');
    } finally {
      try {
        conn.close();
      } catch {
        // Ignore
      }
    }
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'ERR-02: Invalid Sequence - rejects DATA before RCPT TO',
  async fn() {
    const conn = await connectToSmtp('localhost', TEST_PORT);

    try {
      await waitForGreeting(conn);
      await sendSmtpCommand(conn, 'EHLO test.example.com', '250');
      await sendSmtpCommand(conn, 'MAIL FROM:<test@example.com>', '250');

      // Send DATA without RCPT TO
      const encoder = new TextEncoder();
      await conn.write(encoder.encode('DATA\r\n'));

      const response = await readSmtpResponse(conn);

      // RFC 5321: Should return 503 (bad sequence of commands)
      assertMatch(response, /^503/, 'Should reject DATA before RCPT TO with 503');

      await sendSmtpCommand(conn, 'QUIT', '221');
      console.log('✓ DATA before RCPT TO rejected');
    } finally {
      try {
        conn.close();
      } catch {
        // Ignore
      }
    }
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'ERR-02: Invalid Sequence - allows multiple EHLO commands',
  async fn() {
    const conn = await connectToSmtp('localhost', TEST_PORT);

    try {
      await waitForGreeting(conn);

      // Send multiple EHLO commands
      const response1 = await sendSmtpCommand(conn, 'EHLO test1.example.com', '250');
      assert(response1.includes('250'), 'First EHLO should succeed');

      const response2 = await sendSmtpCommand(conn, 'EHLO test2.example.com', '250');
      assert(response2.includes('250'), 'Second EHLO should succeed');

      const response3 = await sendSmtpCommand(conn, 'EHLO test3.example.com', '250');
      assert(response3.includes('250'), 'Third EHLO should succeed');

      await sendSmtpCommand(conn, 'QUIT', '221');
      console.log('✓ Multiple EHLO commands allowed');
    } finally {
      try {
        conn.close();
      } catch {
        // Ignore
      }
    }
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'ERR-02: Invalid Sequence - rejects second MAIL FROM without RSET',
  async fn() {
    const conn = await connectToSmtp('localhost', TEST_PORT);

    try {
      await waitForGreeting(conn);
      await sendSmtpCommand(conn, 'EHLO test.example.com', '250');
      await sendSmtpCommand(conn, 'MAIL FROM:<sender1@example.com>', '250');

      // Send second MAIL FROM without RSET
      const encoder = new TextEncoder();
      await conn.write(encoder.encode('MAIL FROM:<sender2@example.com>\r\n'));

      const response = await readSmtpResponse(conn);

      // Should return 503 (bad sequence) or 250 (some implementations allow overwrite)
      assertMatch(response, /^(503|250)/, 'Should handle second MAIL FROM');

      await sendSmtpCommand(conn, 'QUIT', '221');
      console.log(`✓ Second MAIL FROM handled: ${response.substring(0, 3)}`);
    } finally {
      try {
        conn.close();
      } catch {
        // Ignore
      }
    }
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'ERR-02: Invalid Sequence - rejects DATA without MAIL FROM',
  async fn() {
    const conn = await connectToSmtp('localhost', TEST_PORT);

    try {
      await waitForGreeting(conn);
      await sendSmtpCommand(conn, 'EHLO test.example.com', '250');

      // Send DATA without MAIL FROM
      const encoder = new TextEncoder();
      await conn.write(encoder.encode('DATA\r\n'));

      const response = await readSmtpResponse(conn);

      // Should return 503 (bad sequence of commands)
      assertMatch(response, /^503/, 'Should reject DATA without MAIL FROM with 503');

      await sendSmtpCommand(conn, 'QUIT', '221');
      console.log('✓ DATA without MAIL FROM rejected');
    } finally {
      try {
        conn.close();
      } catch {
        // Ignore
      }
    }
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'ERR-02: Invalid Sequence - handles commands after QUIT',
  async fn() {
    const conn = await connectToSmtp('localhost', TEST_PORT);

    try {
      await waitForGreeting(conn);
      await sendSmtpCommand(conn, 'EHLO test.example.com', '250');
      await sendSmtpCommand(conn, 'QUIT', '221');

      // Try to send command after QUIT
      const encoder = new TextEncoder();
      let writeSucceeded = false;

      try {
        await conn.write(encoder.encode('EHLO test.example.com\r\n'));
        writeSucceeded = true;

        // If write succeeded, wait to see if we get a response (we shouldn't)
        await new Promise((resolve) => setTimeout(resolve, 500));
      } catch {
        // Write failed - connection already closed (expected)
      }

      // Either write failed or no response received after QUIT (both acceptable)
      assert(true, 'Commands after QUIT handled correctly');
      console.log(`✓ Commands after QUIT handled (write ${writeSucceeded ? 'succeeded but ignored' : 'failed'})`);
    } finally {
      try {
        conn.close();
      } catch {
        // Already closed
      }
    }
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'ERR-02: Invalid Sequence - recovers from syntax error in sequence',
  async fn() {
    const conn = await connectToSmtp('localhost', TEST_PORT);

    try {
      await waitForGreeting(conn);
      await sendSmtpCommand(conn, 'EHLO test.example.com', '250');
      await sendSmtpCommand(conn, 'MAIL FROM:<sender@example.com>', '250');

      // Send RCPT TO with wrong syntax (missing brackets)
      const encoder = new TextEncoder();
      await conn.write(encoder.encode('RCPT TO:recipient@example.com\r\n'));

      const badResponse = await readSmtpResponse(conn);
      assertMatch(badResponse, /^501/, 'Should reject RCPT TO without brackets with 501');

      // Now send valid RCPT TO (session should still be valid)
      const goodResponse = await sendSmtpCommand(conn, 'RCPT TO:<recipient@example.com>', '250');
      assert(goodResponse.includes('250'), 'Should accept valid RCPT TO after syntax error');

      await sendSmtpCommand(conn, 'QUIT', '221');
      console.log('✓ Session recovered from syntax error');
    } finally {
      try {
        conn.close();
      } catch {
        // Ignore
      }
    }
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'ERR-02: Cleanup - Stop SMTP server',
  async fn() {
    await stopTestServer(testServer);
  },
  sanitizeResources: false,
  sanitizeOps: false,
});