feat(quic): replace probe UDP data plane with QUIC datagrams

backend/probe/src/MoShiro.Probe/Link/AgentConnection.cs

@@ -30,6 +30,14 @@ public sealed class AgentConnection
 
     private readonly ConnectionEnv _env;
     private volatile ConnectionSession? _session;
+    private int _previousQuicSourcePort;
+    private QuicDatagramTransport? _activeDatagrams;
+    private readonly object _handshakeGate = new();
+    private readonly Queue<double> _handshakeSamplesMs = new();
+    private long _handshakeAttempts;
+    private long _handshakeSuccesses;
+    private long _handshakeFailures;
+    private long _handshakeTimeouts;
 
     public AgentConnection(KnownAgent endpoint, ConnectionEnv env)
     {
@@ -45,6 +53,38 @@ public sealed class AgentConnection
 
     public long ClockOffsetUs => _session?.Clock.OffsetUs ?? 0;
 
+    public ProbeQuicLinkHealth QuicHealth()
+    {
+        lock (_handshakeGate)
+        {
+            double? p95 = null;
+            if (_handshakeSamplesMs.Count > 0)
+            {
+                double[] sorted = [.. _handshakeSamplesMs.Order()];
+                p95 = sorted[(int)Math.Ceiling(sorted.Length * 0.95) - 1];
+            }
+
+            QuicTransportSnapshot? transport = Volatile.Read(ref _activeDatagrams)?.GetTransportSnapshot();
+            return new ProbeQuicLinkHealth
+            {
+                AgentId = Endpoint.AgentId,
+                IpVersion = Endpoint.IpVersion,
+                Connected = IsConnected,
+                HandshakeAttempts = _handshakeAttempts,
+                HandshakeSuccesses = _handshakeSuccesses,
+                HandshakeFailures = _handshakeFailures,
+                HandshakeTimeouts = _handshakeTimeouts,
+                HandshakeP95Ms = p95,
+                HandshakeSampleCount = _handshakeSamplesMs.Count,
+                TransportPacketLossRate = transport?.PacketLossRate,
+                TransportPacketsSent = transport?.PacketsSent,
+                TransportCongestionEvents = transport?.CongestionEvents,
+                TransportEcnCongestionEvents = transport?.EcnCongestionEvents,
+                PathMtu = transport?.PathMtu,
+            };
+        }
+    }
+
     public async Task RunAsync(CancellationToken ct)
     {
         // 重连的间隔别拉太长：每次尝试本来就要等好几秒（握手上限 30 秒），线路一恢复要尽快接上；带抖动，不会和别的节点撞在一起
@@ -93,10 +133,22 @@ public sealed class AgentConnection
         byte[] agentKey = Convert.FromBase64String(Endpoint.PublicKey);
         (PeerSessionInfo info, TlsFrameTransport transport) = await PeerConnector.ConnectAsync(
             address.ToString(), Endpoint.TcpPort, agentKey, _env.Identity, _env.ProbeId, ProbeApp.Version, 8 << 20, _env.Time, ct);
-        var remote = (IPEndPoint)info.Remote!;
         var data = new DataSession(info.Credentials.SessionIdValue, info.Credentials.Key);
-        using var udp = new UdpMux(new SingleSession(data), null, _env.Clock, new DataPlaneCounters(), _env.Log, remote.AddressFamily == AddressFamily.InterNetworkV6 ? IPAddress.IPv6Any : IPAddress.Any, []);
-        udp.Bind();
+        var remote = (IPEndPoint)info.Remote!;
+        IReadOnlyList<int> quicPorts = Endpoint.EffectiveQuicPorts;
+        int quicPort = quicPorts.Count == 0 ? 7443 : quicPorts[0];
+        using var datagrams = new QuicDatagramTransport(
+            data,
+            _env.Clock,
+            new DataPlaneCounters(),
+            _env.Log,
+            new IPEndPoint(remote.Address, quicPort),
+            agentKey,
+            Volatile.Read(ref _previousQuicSourcePort));
+        Volatile.Write(ref _activeDatagrams, datagrams);
+        datagrams.Bind();
+        using CancellationTokenSource cts = CancellationTokenSource.CreateLinkedTokenSource(ct);
+
         var outbox = new Outbox(8 << 20);
         var clock = new ClockEstimator();
         var shipper = new FragmentShipper(outbox, new NodeId(Endpoint.AgentId), new ProbeId(_env.ProbeId), clock, _env.Time);
@@ -105,7 +157,7 @@ public sealed class AgentConnection
             Clock = _env.Clock,
             Log = _env.Log,
             Session = () => data,
-            Udp = udp,
+            Datagrams = datagrams,
             PeerAddress = remote.Address,
             PeerSpkiSha256 = NodeIdentity.Fingerprint(agentKey),
             KnockKey = Knock.DeriveKey(_env.Identity, agentKey),
@@ -117,14 +169,52 @@ public sealed class AgentConnection
         var rpc = new RpcSession<ConnectionSession>(transport, s_router, session, _env.Time);
         rpc.OnBinary = (_, _) => ValueTask.CompletedTask;
 
-        using CancellationTokenSource cts = CancellationTokenSource.CreateLinkedTokenSource(ct);
         Task run = rpc.RunAsync(cts.Token);
-        Task receive = udp.RunAsync(cts.Token);
+        Task receive = datagrams.RunAsync(cts.Token);
         Task pump = PumpAsync(rpc, outbox, cts.Token);
         try
         {
             // 先同步时钟（块头里要带偏移）；Agent 随后推送线路任务集
             await SyncClockAsync(rpc, clock, rounds: 5, cts.Token);
+            lock (_handshakeGate)
+            {
+                _handshakeAttempts++;
+            }
+
+            try
+            {
+                await datagrams.ConnectAsync(cts.Token);
+                lock (_handshakeGate)
+                {
+                    _handshakeSuccesses++;
+                    if (datagrams.HandshakeDurationMs is { } elapsed)
+                    {
+                        _handshakeSamplesMs.Enqueue(elapsed);
+                        while (_handshakeSamplesMs.Count > 128)
+                        {
+                            _handshakeSamplesMs.Dequeue();
+                        }
+                    }
+                }
+            }
+            catch (Exception ex) when (!(ex is OperationCanceledException && cts.IsCancellationRequested))
+            {
+                lock (_handshakeGate)
+                {
+                    _handshakeFailures++;
+                    if (ex is TimeoutException)
+                    {
+                        _handshakeTimeouts++;
+                    }
+                }
+
+                throw;
+            }
+            if (datagrams.BoundPorts.Count > 0)
+            {
+                Volatile.Write(ref _previousQuicSourcePort, datagrams.BoundPorts[0]);
+            }
+
             backoff.Reset();
             _session = session;
             _env.Log.Info("agent session up", ("agent", Endpoint.AgentId), ("offset_us", clock.OffsetUs));
@@ -137,6 +227,7 @@ public sealed class AgentConnection
         finally
         {
             _session = null;
+            Volatile.Write(ref _activeDatagrams, null);
             await cts.CancelAsync();
             await session.StopAllAsync();
             await Quiet(run);

backend/probe/src/MoShiro.Probe/Link/AgentDirectory.cs

@@ -73,14 +73,15 @@ public sealed class AgentDirectory
         _trust.Update(result.TrustChain);
         foreach (AgentEndpoint agent in result.Agents)
         {
+            List<int> ports = agent.QuicPorts.Count > 0 ? agent.QuicPorts : agent.LegacyUdpPorts ?? [];
             if (!string.IsNullOrWhiteSpace(agent.Host))
             {
-                next.Add(new KnownAgent { AgentId = agent.AgentId.Value, Host = agent.Host, TcpPort = agent.TcpPort, PublicKey = agent.PublicKey });
+                next.Add(new KnownAgent { AgentId = agent.AgentId.Value, Host = agent.Host, TcpPort = agent.TcpPort, QuicPorts = [.. ports], PublicKey = agent.PublicKey });
             }
 
             if (!string.IsNullOrWhiteSpace(agent.Ipv6Host))
             {
-                next.Add(new KnownAgent { AgentId = agent.AgentId.Value, Host = agent.Ipv6Host, TcpPort = agent.TcpPort, PublicKey = agent.PublicKey, IpVersion = IpVersions.V6 });
+                next.Add(new KnownAgent { AgentId = agent.AgentId.Value, Host = agent.Ipv6Host, TcpPort = agent.TcpPort, QuicPorts = [.. ports], PublicKey = agent.PublicKey, IpVersion = IpVersions.V6 });
             }
         }
         lock (_gate)
@@ -111,5 +112,5 @@ public sealed class AgentDirectory
         a.Count == b.Count && a.Zip(b).All(p => Equal(p.First, p.Second));
 
     public static bool Equal(KnownAgent a, KnownAgent b) =>
-        a.AgentId == b.AgentId && a.IpVersion == b.IpVersion && a.Host == b.Host && a.TcpPort == b.TcpPort && a.PublicKey == b.PublicKey;
+        a.AgentId == b.AgentId && a.IpVersion == b.IpVersion && a.Host == b.Host && a.TcpPort == b.TcpPort && a.QuicPorts.SequenceEqual(b.QuicPorts) && a.PublicKey == b.PublicKey;
 }

backend/probe/src/MoShiro.Probe/ProbeApp.cs

@@ -45,7 +45,7 @@ public sealed class ProbeApp : IDisposable
             NodeId = identity.NodeId,
             NodeVersion = Version,
             Capabilities = [MoShiroCapabilities.Base],
-            HeartbeatExtra = () => JsonSerializer.SerializeToElement(new ProbeHeartbeatExtra { Update = update?.Status(), Ipv6 = Ipv6Diagnostics.Sample(null, Environment.GetEnvironmentVariable("MOSHIRO_NETWORK_SCOPE"), Environment.GetEnvironmentVariable("HOST_PROC")) }, MoShiroJsonContext.Default.ProbeHeartbeatExtra),
+            HeartbeatExtra = () => JsonSerializer.SerializeToElement(new ProbeHeartbeatExtra { Update = update?.Status(), Ipv6 = Ipv6Diagnostics.Sample(null, Environment.GetEnvironmentVariable("MOSHIRO_NETWORK_SCOPE"), Environment.GetEnvironmentVariable("HOST_PROC")), QuicLinks = SnapshotQuicLinks() }, MoShiroJsonContext.Default.ProbeHeartbeatExtra),
             HelloMeta = () => JsonSerializer.SerializeToElement(new ProbeHelloMeta { Owners = [.. trust.Controllers], Platform = PlatformDetector.Detect(), Ipv6 = Ipv6Diagnostics.Sample(null, Environment.GetEnvironmentVariable("MOSHIRO_NETWORK_SCOPE"), Environment.GetEnvironmentVariable("HOST_PROC")) }, MoShiroJsonContext.Default.ProbeHelloMeta),
         };
         var list = new StateHandler<ProbeAgentList>(
@@ -101,6 +101,14 @@ public sealed class ProbeApp : IDisposable
         }
     }
 
+    private List<ProbeQuicLinkHealth> SnapshotQuicLinks()
+    {
+        lock (_connections)
+        {
+            return [.. _connections.Values.Select(r => r.Connection.QuicHealth())];
+        }
+    }
+
     public async Task RunAsync(CancellationToken ct)
     {
         _log.Info("moshiro probe starting", MoShiro.Protocol.BuildInfo.Fields);

backend/probe/src/MoShiro.Probe/ProbeConfig.cs

@@ -57,6 +57,15 @@ public sealed class KnownAgent
     [JsonPropertyName("tcp_port")]
     public int TcpPort { get; set; }
 
+    [JsonPropertyName("quic_ports")]
+    public List<int> QuicPorts { get; set; } = [7443];
+
+    [JsonPropertyName("udp_ports")]
+    public List<int>? LegacyUdpPorts { get; set; }
+
+    [JsonIgnore]
+    public IReadOnlyList<int> EffectiveQuicPorts => LegacyUdpPorts ?? QuicPorts;
+
     /// <summary>Agent 的 TLS 证书公钥（SPKI，base64）：证书按它的 SHA-256 指纹固定，敲门密钥由它派生。</summary>
     [JsonPropertyName("public_key")]
     public string PublicKey { get; set; } = "";