natsdotnet/tests/NATS.Server.Tests/TlsServerTests.cs

using System.Net;
using System.Net.Security;
using System.Net.Sockets;
using System.Text;
using Microsoft.Extensions.Logging.Abstractions;
using NATS.Server;

namespace NATS.Server.Tests;

public class TlsServerTests : IAsyncLifetime
{
    private readonly NatsServer _server;
    private readonly int _port;
    private readonly CancellationTokenSource _cts = new();
    private readonly string _certPath;
    private readonly string _keyPath;

    public TlsServerTests()
    {
        _port = GetFreePort();
        (_certPath, _keyPath) = TlsHelperTests.GenerateTestCertFiles();
        _server = new NatsServer(
            new NatsOptions
            {
                Port = _port,
                TlsCert = _certPath,
                TlsKey = _keyPath,
            },
            NullLoggerFactory.Instance);
    }

    public async Task InitializeAsync()
    {
        _ = _server.StartAsync(_cts.Token);
        await _server.WaitForReadyAsync();
    }

    public async Task DisposeAsync()
    {
        await _cts.CancelAsync();
        _server.Dispose();
        File.Delete(_certPath);
        File.Delete(_keyPath);
    }

    [Fact]
    public async Task Tls_client_connects_and_receives_info()
    {
        using var tcp = new TcpClient();
        await tcp.ConnectAsync(IPAddress.Loopback, _port);
        using var netStream = tcp.GetStream();

        // Read INFO (sent before TLS upgrade in Mode 2)
        var buf = new byte[4096];
        var read = await netStream.ReadAsync(buf);
        var info = Encoding.ASCII.GetString(buf, 0, read);
        info.ShouldStartWith("INFO ");
        info.ShouldContain("\"tls_required\":true");

        // Upgrade to TLS
        using var sslStream = new SslStream(netStream, false, (_, _, _, _) => true);
        await sslStream.AuthenticateAsClientAsync("localhost");

        // Send CONNECT + PING over TLS
        await sslStream.WriteAsync("CONNECT {}\r\nPING\r\n"u8.ToArray());
        await sslStream.FlushAsync();

        // Read PONG
        var pongBuf = new byte[256];
        read = await sslStream.ReadAsync(pongBuf);
        var pong = Encoding.ASCII.GetString(pongBuf, 0, read);
        pong.ShouldContain("PONG");
    }

    [Fact]
    public async Task Tls_pubsub_works_over_encrypted_connection()
    {
        using var tcp1 = new TcpClient();
        await tcp1.ConnectAsync(IPAddress.Loopback, _port);
        using var ssl1 = await UpgradeToTlsAsync(tcp1);

        using var tcp2 = new TcpClient();
        await tcp2.ConnectAsync(IPAddress.Loopback, _port);
        using var ssl2 = await UpgradeToTlsAsync(tcp2);

        // Sub on client 1
        await ssl1.WriteAsync("CONNECT {}\r\nSUB test 1\r\nPING\r\n"u8.ToArray());
        await ssl1.FlushAsync();

        // Wait for PONG to confirm subscription is registered
        var pongBuf = new byte[256];
        var pongRead = await ssl1.ReadAsync(pongBuf);
        var pongStr = Encoding.ASCII.GetString(pongBuf, 0, pongRead);
        pongStr.ShouldContain("PONG");

        // Pub on client 2
        await ssl2.WriteAsync("CONNECT {}\r\nPUB test 5\r\nhello\r\nPING\r\n"u8.ToArray());
        await ssl2.FlushAsync();

        // Client 1 should receive MSG (may arrive across multiple TLS records)
        var msg = await ReadUntilAsync(ssl1, "hello");
        msg.ShouldContain("MSG test 1 5");
        msg.ShouldContain("hello");
    }

    private static async Task<string> ReadUntilAsync(Stream stream, string expected, int timeoutMs = 5000)
    {
        using var cts = new CancellationTokenSource(timeoutMs);
        var sb = new StringBuilder();
        var buf = new byte[4096];
        while (!sb.ToString().Contains(expected))
        {
            var n = await stream.ReadAsync(buf, cts.Token);
            if (n == 0) break;
            sb.Append(Encoding.ASCII.GetString(buf, 0, n));
        }
        return sb.ToString();
    }

    private static async Task<SslStream> UpgradeToTlsAsync(TcpClient tcp)
    {
        var netStream = tcp.GetStream();
        var buf = new byte[4096];
        _ = await netStream.ReadAsync(buf); // Read INFO (discard)

        var ssl = new SslStream(netStream, false, (_, _, _, _) => true);
        await ssl.AuthenticateAsClientAsync("localhost");
        return ssl;
    }

    private static int GetFreePort()
    {
        using var sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        sock.Bind(new IPEndPoint(IPAddress.Loopback, 0));
        return ((IPEndPoint)sock.LocalEndPoint!).Port;
    }
}