UA-.NETStandard/tests/Opc.Ua.PubSub.Tests/Security/SecurityTokenWindowTests.cs

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using System;
using System.Collections.Concurrent;
using System.Threading.Tasks;
using NUnit.Framework;
using Opc.Ua.PubSub.Encoding;
using Opc.Ua.PubSub.Security;

namespace Opc.Ua.PubSub.Tests.Security
{
    /// <summary>
    /// Tests for <see cref="SecurityTokenWindow"/>.
    /// </summary>
    [TestFixture]
    [TestSpec("7.2.4.4.3.1", Summary = "PubSub replay-window")]
    public class SecurityTokenWindowTests
    {
        private static readonly uint[] s_expectedTokenIds = [1U, 7U];

        private static byte[] MakeNonce(byte seed)
        {
            byte[] nonce = new byte[12];
            for (int i = 0; i < nonce.Length; i++)
            {
                nonce[i] = (byte)(seed + i);
            }
            return nonce;
        }

        [Test]
        public void TryAccept_AcceptsFirstMessageForRegisteredToken()
        {
            var window = new SecurityTokenWindow();
            window.RegisterToken(1U);
            Assert.That(window.TryAccept(1U, 1UL, MakeNonce(1)), Is.True);
        }

        [Test]
        public void TryAccept_RejectsUnknownToken()
        {
            var window = new SecurityTokenWindow();
            Assert.That(window.TryAccept(99U, 1UL, MakeNonce(1)), Is.False);
        }

        [Test]
        public void TryAccept_RejectsReplayedSequenceNumber()
        {
            var window = new SecurityTokenWindow();
            window.RegisterToken(1U);
            Assert.Multiple(() =>
            {
                Assert.That(window.TryAccept(1U, 1UL, MakeNonce(1)), Is.True);
                Assert.That(window.TryAccept(1U, 1UL, MakeNonce(2)), Is.False);
            });
        }

        [Test]
        public void TryAccept_RejectsReusedNonce()
        {
            var window = new SecurityTokenWindow();
            window.RegisterToken(1U);
            byte[] nonce = MakeNonce(7);
            Assert.Multiple(() =>
            {
                Assert.That(window.TryAccept(1U, 1UL, nonce), Is.True);
                Assert.That(window.TryAccept(1U, 2UL, nonce), Is.False);
            });
        }

        [Test]
        public void TryAccept_AcceptsDifferentTokenWithSameSequence()
        {
            var window = new SecurityTokenWindow();
            window.RegisterToken(1U);
            window.RegisterToken(2U);
            byte[] nonce = MakeNonce(1);
            Assert.Multiple(() =>
            {
                Assert.That(window.TryAccept(1U, 5UL, nonce), Is.True);
                Assert.That(window.TryAccept(2U, 5UL, nonce), Is.True);
            });
        }

        [Test]
        public void ScopedReplayRejectsNonceReuseGloballyAcrossPublishersAndWriterGroups()
        {
            const uint tokenId = 1U;
            var window = new SecurityTokenWindow(historySize: 4);
            window.RegisterToken(tokenId);
            var scopedWindow = (IScopedSecurityTokenWindow)window;
            PublisherId publisherA = PublisherId.FromUInt32(100U);
            PublisherId publisherB = PublisherId.FromUInt32(200U);
            byte[] reusedNonce = MakeNonce(1);

            Assert.That(
                scopedWindow.TryAccept(publisherA, 1, tokenId, 1, reusedNonce),
                Is.True);
            for (ulong sequenceNumber = 2; sequenceNumber <= 8; sequenceNumber++)
            {
                Assert.That(
                    scopedWindow.TryAccept(
                        publisherA,
                        1,
                        tokenId,
                        sequenceNumber,
                        MakeNonce((byte)(sequenceNumber + 20))),
                    Is.True);
            }

            Assert.Multiple(() =>
            {
                Assert.That(
                    scopedWindow.TryAccept(publisherB, 1, tokenId, 1, reusedNonce),
                    Is.False);
                Assert.That(
                    scopedWindow.TryAccept(publisherA, 2, tokenId, 1, reusedNonce),
                    Is.False);
                Assert.That(
                    scopedWindow.TryAccept(publisherB, 1, tokenId, 1, MakeNonce(50)),
                    Is.True);
                Assert.That(
                    scopedWindow.TryAccept(publisherA, 2, tokenId, 1, MakeNonce(51)),
                    Is.True);
            });
        }

        [Test]
        public void RetireToken_RejectsSubsequentMessages()
        {
            var window = new SecurityTokenWindow();
            window.RegisterToken(1U);
            window.RetireToken(1U);
            Assert.That(window.TryAccept(1U, 1UL, MakeNonce(1)), Is.False);
        }

        [Test]
        public void RetireTokenClearsScopedReplayStateAndKeepsOtherTokens()
        {
            const uint retiredToken = 1U;
            const uint survivingToken = 7U;
            var window = new SecurityTokenWindow(historySize: 4);
            window.RegisterToken(retiredToken);
            window.RegisterToken(survivingToken);
            var scopedWindow = (IScopedSecurityTokenWindow)window;
            PublisherId publisherA = PublisherId.FromUInt32(100U);
            PublisherId publisherB = PublisherId.FromUInt32(200U);

            // Populate two publisher/writer-group scopes on the token that is
            // about to be retired, plus one scope on a token that survives.
            Assert.Multiple(() =>
            {
                Assert.That(
                    scopedWindow.TryAccept(publisherA, 1, retiredToken, 5, MakeNonce(10)),
                    Is.True);
                Assert.That(
                    scopedWindow.TryAccept(publisherB, 2, retiredToken, 5, MakeNonce(20)),
                    Is.True);
                Assert.That(
                    scopedWindow.TryAccept(publisherA, 1, survivingToken, 5, MakeNonce(30)),
                    Is.True);
            });

            window.RetireToken(retiredToken);

            Assert.Multiple(() =>
            {
                Assert.That(window.RegisteredTokens, Is.EquivalentTo(new[] { survivingToken }));
                // The retired token no longer accepts anything.
                Assert.That(
                    scopedWindow.TryAccept(publisherA, 1, retiredToken, 5, MakeNonce(10)),
                    Is.False);
                // The surviving token keeps its committed sequence, so replaying
                // sequence 5 on the retained scope is still rejected.
                Assert.That(
                    scopedWindow.TryAccept(publisherA, 1, survivingToken, 5, MakeNonce(31)),
                    Is.False);
            });
        }

        [Test]
        public void Reset_ClearsAllState()
        {
            var window = new SecurityTokenWindow();
            window.RegisterToken(1U);
            Assert.That(window.TryAccept(1U, 1UL, MakeNonce(1)), Is.True);
            window.Reset();
            Assert.Multiple(() =>
            {
                Assert.That(window.RegisteredTokens, Is.Empty);
                Assert.That(window.TryAccept(1U, 1UL, MakeNonce(1)), Is.False);
            });
        }

        [Test]
        public void TryAccept_RejectsReplayedSequenceAfterWindowAdvancesPastIt()
        {
            // Monotonic window: a sequence that has fallen below the
            // lower edge of the window is permanently rejected (no
            // eviction-replay).
            var window = new SecurityTokenWindow(historySize: 4);
            window.RegisterToken(1U);
            for (ulong seq = 1; seq <= 8; seq++)
            {
                Assert.That(
                    window.TryAccept(1U, seq, MakeNonce((byte)seq)),
                    Is.True,
                    $"seq {seq} should be accepted");
            }
            // seq 1 is now far below (highest - historySize) and must
            // stay rejected even with a fresh, never-seen nonce.
            Assert.That(window.TryAccept(1U, 1UL, MakeNonce(80)), Is.False);
        }

        [Test]
        public void TryAccept_RejectsReplayAfterMoreThanHistorySizeNewerMessages()
        {
            const int historySize = 8;
            var window = new SecurityTokenWindow(historySize);
            window.RegisterToken(1U);

            byte[] capturedNonce = MakeNonce(3);
            Assert.That(window.TryAccept(1U, 5UL, capturedNonce), Is.True);

            // Advance the window well past the captured sequence.
            for (ulong seq = 6; seq <= 5 + (historySize * 4); seq++)
            {
                Assert.That(
                    window.TryAccept(1U, seq, MakeNonce((byte)(seq + 100))),
                    Is.True);
            }

            // Replaying the captured frame (same sequence + same nonce)
            // is rejected.
            Assert.That(window.TryAccept(1U, 5UL, capturedNonce), Is.False);
        }

        [Test]
        public void TryAccept_AcceptsOutOfOrderWithinWindow()
        {
            var window = new SecurityTokenWindow(historySize: 16);
            window.RegisterToken(1U);
            Assert.Multiple(() =>
            {
                Assert.That(window.TryAccept(1U, 10UL, MakeNonce(10)), Is.True);
                // Older but still inside the window.
                Assert.That(window.TryAccept(1U, 7UL, MakeNonce(7)), Is.True);
                Assert.That(window.TryAccept(1U, 9UL, MakeNonce(9)), Is.True);
                // Duplicate of an already-accepted in-window sequence.
                Assert.That(window.TryAccept(1U, 9UL, MakeNonce(99)), Is.False);
                // Newer sequence advances the window.
                Assert.That(window.TryAccept(1U, 11UL, MakeNonce(11)), Is.True);
            });
        }

        [Test]
        public void TryAccept_HandlesSixteenBitBoundaryWithoutFalseRejection()
        {
            // The wire SequenceNumber crosses the 16-bit boundary; the
            // widened monotonic counter keeps advancing so no spurious
            // wrap rejection occurs around 0xFFFF.
            var window = new SecurityTokenWindow(historySize: 64);
            window.RegisterToken(1U);
            Assert.Multiple(() =>
            {
                Assert.That(window.TryAccept(1U, 0xFFFEUL, MakeNonce(1)), Is.True);
                Assert.That(window.TryAccept(1U, 0xFFFFUL, MakeNonce(2)), Is.True);
                Assert.That(window.TryAccept(1U, 0x10000UL, MakeNonce(3)), Is.True);
                Assert.That(window.TryAccept(1U, 0x10001UL, MakeNonce(4)), Is.True);
                // Duplicate at the boundary is rejected.
                Assert.That(window.TryAccept(1U, 0xFFFFUL, MakeNonce(5)), Is.False);
            });
        }

        [Test]
        public void TryAccept_HandlesLargeForwardJump()
        {
            var window = new SecurityTokenWindow(historySize: 8);
            window.RegisterToken(1U);
            Assert.Multiple(() =>
            {
                Assert.That(window.TryAccept(1U, 1UL, MakeNonce(1)), Is.True);
                // Jump far beyond the window width — clears the bitmap.
                Assert.That(window.TryAccept(1U, 1_000_000UL, MakeNonce(2)), Is.True);
                // The old sequence is now ancient and stays rejected.
                Assert.That(window.TryAccept(1U, 1UL, MakeNonce(3)), Is.False);
                // A duplicate of the new highest is rejected.
                Assert.That(window.TryAccept(1U, 1_000_000UL, MakeNonce(4)), Is.False);
            });
        }

        [Test]
        public void Constructor_RejectsNonPositiveHistorySize()
        {
            Assert.That(
                () => new SecurityTokenWindow(historySize: 0),
                Throws.TypeOf<ArgumentOutOfRangeException>());
            Assert.That(
                () => new SecurityTokenWindow(historySize: -1),
                Throws.TypeOf<ArgumentOutOfRangeException>());
        }

        [Test]
        public void ConstructorRejectsNonPositiveNonceFilterSize()
        {
            Assert.That(
                () => new SecurityTokenWindow(
                    historySize: 1024,
                    timeProvider: null,
                    nonceFilterSizeInBytes: 0),
                Throws.TypeOf<ArgumentOutOfRangeException>());
            Assert.That(
                () => new SecurityTokenWindow(
                    historySize: 1024,
                    timeProvider: null,
                    nonceFilterSizeInBytes: -1),
                Throws.TypeOf<ArgumentOutOfRangeException>());
        }

        [Test]
        public void Properties_ReflectConfiguration()
        {
            TimeProvider clock = TimeProvider.System;
            var window = new SecurityTokenWindow(
                historySize: 16,
                timeProvider: clock,
                nonceFilterSizeInBytes: 2048);
            Assert.Multiple(() =>
            {
                Assert.That(window.HistorySize, Is.EqualTo(16));
                Assert.That(window.TimeProvider, Is.SameAs(clock));
                Assert.That(window.NonceFilterSizeInBytes, Is.EqualTo(2048));
            });
        }

        [Test]
        public void RegisteredTokens_ReturnsRegisteredIds()
        {
            var window = new SecurityTokenWindow();
            window.RegisterToken(1U);
            window.RegisterToken(7U);
            Assert.That(window.RegisteredTokens, Is.EquivalentTo(s_expectedTokenIds));
        }

        [Test]
        public void RegisterToken_IsIdempotent()
        {
            var window = new SecurityTokenWindow();
            window.RegisterToken(1U);
            window.RegisterToken(1U);
            Assert.That(window.RegisteredTokens, Has.Count.EqualTo(1));
        }

        [Test]
        public async Task TryAccept_ConcurrentInvocationDoesNotLoseEntries()
        {
            var window = new SecurityTokenWindow(historySize: 100_000);
            window.RegisterToken(1U);
            const int parallelism = 8;
            const int perTask = 500;
            var accepted = new ConcurrentBag<ulong>();
            var workers = new Task[parallelism];
            for (int t = 0; t < parallelism; t++)
            {
                int taskIndex = t;
                workers[t] = Task.Run(() =>
                {
                    for (int i = 0; i < perTask; i++)
                    {
                        ulong sequenceNumber = (ulong)((taskIndex * perTask) + i + 1);
                        byte[] nonce = new byte[12];
                        // Distinct nonce per (task, i) pair.
                        nonce[0] = (byte)taskIndex;
                        nonce[1] = (byte)(i & 0xff);
                        nonce[2] = (byte)((i >> 8) & 0xff);
                        if (window.TryAccept(1U, sequenceNumber, nonce))
                        {
                            accepted.Add(sequenceNumber);
                        }
                    }
                });
            }
            await Task.WhenAll(workers).ConfigureAwait(false);
            Assert.That(accepted, Has.Count.EqualTo(parallelism * perTask));
        }
    }
}