mailer/test/suite/smtpserver_security/test.sec-06.ip-reputation.test.ts

/**
 * SEC-06: IP Reputation Tests
 * Tests SMTP server IP reputation checking infrastructure
 *
 * NOTE: Current implementation uses placeholder IP reputation checker
 * that accepts all connections. These tests verify the infrastructure
 * is in place and working correctly with legitimate traffic.
 */

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

const TEST_PORT = 25260;
let testServer: ITestServer;

Deno.test({
  name: 'SEC-06: 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: 'SEC-06: IP Reputation - accepts localhost connections',
  async fn() {
    const conn = await connectToSmtp('localhost', TEST_PORT);

    try {
      // IP reputation check should pass for localhost
      const greeting = await waitForGreeting(conn);
      assert(greeting.includes('220'), 'Should receive greeting after IP reputation check');

      await sendSmtpCommand(conn, 'EHLO localhost', '250');
      await sendSmtpCommand(conn, 'QUIT', '221');

      console.log('✓ IP reputation check passed for localhost');
    } finally {
      try {
        conn.close();
      } catch {
        // Ignore
      }
    }
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'SEC-06: IP Reputation - accepts known good sender',
  async fn() {
    const conn = await connectToSmtp('localhost', TEST_PORT);

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

      // Legitimate sender should be accepted
      const mailFromResponse = await sendSmtpCommand(conn, 'MAIL FROM:<test@example.com>', '250');
      assert(mailFromResponse.includes('250'), 'Should accept legitimate sender');

      // Legitimate recipient should be accepted
      const rcptToResponse = await sendSmtpCommand(conn, 'RCPT TO:<recipient@example.com>', '250');
      assert(rcptToResponse.includes('250'), 'Should accept legitimate recipient');

      await sendSmtpCommand(conn, 'QUIT', '221');

      console.log('✓ Known good sender accepted - IP reputation allows legitimate traffic');
    } finally {
      try {
        conn.close();
      } catch {
        // Ignore
      }
    }
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'SEC-06: IP Reputation - handles multiple connections from same IP',
  async fn() {
    const connections: Deno.Conn[] = [];
    const connectionResults: Promise<void>[] = [];
    const totalConnections = 3;

    // Create multiple connections rapidly
    for (let i = 0; i < totalConnections; i++) {
      const connectionPromise = (async () => {
        try {
          const conn = await connectToSmtp('localhost', TEST_PORT);
          connections.push(conn);

          // Wait for greeting
          const greeting = await waitForGreeting(conn);
          assert(greeting.includes('220'), `Connection ${i + 1} should receive greeting`);

          // Send EHLO
          const ehloResponse = await sendSmtpCommand(conn, 'EHLO testclient', '250');
          assert(ehloResponse.includes('250'), `Connection ${i + 1} should accept EHLO`);

          // Graceful quit
          await sendSmtpCommand(conn, 'QUIT', '221');

          console.log(`✓ Connection ${i + 1} completed successfully`);
        } catch (err: any) {
          console.error(`Connection ${i + 1} error:`, err.message);
          throw err;
        }
      })();

      connectionResults.push(connectionPromise);

      // Small delay between connections
      if (i < totalConnections - 1) {
        await new Promise(resolve => setTimeout(resolve, 100));
      }
    }

    // Wait for all connections to complete
    await Promise.all(connectionResults);

    // Clean up all connections
    for (const conn of connections) {
      try {
        conn.close();
      } catch {
        // Already closed
      }
    }

    console.log('✓ All connections from same IP handled successfully');
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'SEC-06: IP Reputation - complete SMTP flow with reputation check',
  async fn() {
    const conn = await connectToSmtp('localhost', TEST_PORT);

    try {
      // Full SMTP transaction should work after IP reputation check
      await waitForGreeting(conn);
      await sendSmtpCommand(conn, 'EHLO test.example.com', '250');
      await sendSmtpCommand(conn, 'MAIL FROM:<sender@example.com>', '250');
      await sendSmtpCommand(conn, 'RCPT TO:<recipient@example.com>', '250');

      // Send DATA
      await sendSmtpCommand(conn, 'DATA', '354');

      // Send email content
      const encoder = new TextEncoder();
      const emailContent = `Subject: IP Reputation Test\r\nFrom: sender@example.com\r\nTo: recipient@example.com\r\n\r\nThis email tests IP reputation checking.\r\n`;
      await conn.write(encoder.encode(emailContent));
      await conn.write(encoder.encode('.\r\n'));

      // Should receive acceptance
      const decoder = new TextDecoder();
      const responseBuffer = new Uint8Array(1024);
      const bytesRead = await conn.read(responseBuffer);
      const response = decoder.decode(responseBuffer.subarray(0, bytesRead || 0));

      assert(response.includes('250'), 'Should accept email after IP reputation check');

      await sendSmtpCommand(conn, 'QUIT', '221');

      console.log('✓ Complete SMTP flow works with IP reputation infrastructure');
    } finally {
      try {
        conn.close();
      } catch {
        // Ignore
      }
    }
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'SEC-06: IP Reputation - infrastructure placeholder test',
  async fn() {
    // This test documents that IP reputation checking is currently a placeholder
    // Future implementations should:
    // 1. Check against real IP reputation databases
    // 2. Reject connections from blacklisted IPs
    // 3. Detect suspicious hostnames
    // 4. Identify spam patterns
    // 5. Apply rate limiting based on reputation score

    console.log('ℹ️  IP Reputation Infrastructure Status:');
    console.log('   - IPReputationChecker class exists');
    console.log('   - Currently returns placeholder data (score: 100, not blacklisted)');
    console.log('   - Infrastructure is in place for future implementation');
    console.log('   - Tests verify legitimate traffic is accepted');

    assert(true, 'Infrastructure test passed');
  },
  sanitizeResources: false,
  sanitizeOps: false,
});

Deno.test({
  name: 'SEC-06: Cleanup - Stop SMTP server',
  async fn() {
    await stopTestServer(testServer);
  },
  sanitizeResources: false,
  sanitizeOps: false,
});