Add native SCTP lab profile

Author: ammarheidari

README.md

@@ -45,7 +45,7 @@ The first production milestone is M3UA over a transport abstraction. SCCP, TCAP,
 | Observability | Phase 7 profile added for commercial metrics, trace categories, and health signals |
 | Deployment profiles | Phase 7 profiles added for commercial Linux and local development use |
 | Phase 7 status | Commercialization foundation complete; commercial production remains blocked on native SCTP verification, external lab evidence, signing, and SBOM |
-| Native SCTP implementation | Phase 8 started: Linux SCTP socket probe, socket factory, endpoint connection planner, native socket adapter, client connector, and server listener added; full production readiness still requires native transport completion and lab verification |
+| Native SCTP implementation | Phase 8 started: Linux SCTP socket probe, socket factory, endpoint connection planner, native socket adapter, client connector, server listener, and opt-in lab profile added; full production readiness still requires native transport completion and lab verification |
 
 ## Requirements
 

docs/PHASE8_NATIVE_SCTP.md

@@ -71,3 +71,14 @@ NativeSctpSocketAdapter association = await listener.AcceptAsync(options);
 ```
 
 The listener shares the same socket factory and unsupported-platform behavior as the connector. Real accept/send/receive verification belongs in Linux SCTP lab runs.
+
+## Lab Profile
+
+Native SCTP lab tests are opt-in through `SIGTRAN_NATIVE_SCTP_LAB=1`.
+
+```powershell
+$env:SIGTRAN_NATIVE_SCTP_LAB = "1"
+dotnet run --project src\sigtran.net.Tests\sigtran.net.Tests.csproj
+```
+
+`NativeSctpLab.CreateFromEnvironment()` exposes the current lab profile. The default loopback endpoint is `127.0.0.1:2905`.

docs/SCTP_TRANSPORT.md

@@ -134,3 +134,5 @@ The probe does not mark the transport production-ready by itself. It is the firs
 `NativeSctpConnector` performs the client-side bind/connect path and returns an established native adapter.
 
 `NativeSctpListener` provides the server-side bind/listen/accept path for Linux native SCTP lab scenarios.
+
+`NativeSctpLab.CreateFromEnvironment()` keeps native SCTP integration verification opt-in through `SIGTRAN_NATIVE_SCTP_LAB=1`.

src/sigtran.net.Tests/Program.cs

@@ -36,6 +36,7 @@
 Run("Native SCTP socket adapter reports lifecycle health", NativeSctpSocketAdapterReportsLifecycleHealth);
 Run("Native SCTP connector reports unsupported platform safely", NativeSctpConnectorReportsUnsupportedPlatformSafely);
 Run("Native SCTP listener validates options and unsupported platform", NativeSctpListenerValidatesOptionsAndUnsupportedPlatform);
+Run("Native SCTP lab profile is opt-in", NativeSctpLabProfileIsOptIn);
 Run("TCAP BER element encodes short and long lengths", TcapBerElementEncodesShortAndLongLengths);
 Run("TCAP transaction identifiers use BER context tags", TcapTransactionIdentifiersUseBerContextTags);
 Run("TCAP BER Invoke component round-trips", TcapBerInvokeComponentRoundTrips);
@@ -511,6 +512,27 @@ static void NativeSctpListenerValidatesOptionsAndUnsupportedPlatform()
     }
 }
 
+static void NativeSctpLabProfileIsOptIn()
+{
+    string? previous = Environment.GetEnvironmentVariable(NativeSctpLabProfile.EnableEnvironmentVariable);
+    try
+    {
+        Environment.SetEnvironmentVariable(NativeSctpLabProfile.EnableEnvironmentVariable, null);
+        NativeSctpLabProfile disabled = NativeSctpLab.CreateFromEnvironment();
+        Assert(!disabled.Enabled, "native SCTP lab should be disabled by default");
+        AssertEqual("127.0.0.1", disabled.LoopbackEndpoint.Host, "native SCTP lab loopback host");
+
+        Environment.SetEnvironmentVariable(NativeSctpLabProfile.EnableEnvironmentVariable, "1");
+        NativeSctpLabProfile enabled = NativeSctpLab.CreateFromEnvironment();
+        Assert(enabled.Enabled, "native SCTP lab should enable from environment");
+        Assert(enabled.Describe().Contains("enabled=True", StringComparison.Ordinal), enabled.Describe());
+    }
+    finally
+    {
+        Environment.SetEnvironmentVariable(NativeSctpLabProfile.EnableEnvironmentVariable, previous);
+    }
+}
+
 static void TcapBerElementEncodesShortAndLongLengths()
 {
     Span<byte> shortBuffer = stackalloc byte[8];

src/sigtran.net/Layers/SCTP/NativeSctpLabProfile.cs

@@ -0,0 +1,58 @@
+namespace sigtran.net.Layers.SCTP;
+
+/// <summary>
+/// Describes an opt-in native SCTP lab profile.
+/// </summary>
+public sealed class NativeSctpLabProfile
+{
+    /// <summary>The environment variable that enables native SCTP lab tests.</summary>
+    public const string EnableEnvironmentVariable = "SIGTRAN_NATIVE_SCTP_LAB";
+
+    /// <summary>Creates a native SCTP lab profile.</summary>
+    /// <param name="enabled">Whether the profile is enabled.</param>
+    /// <param name="loopbackEndpoint">The loopback SCTP endpoint.</param>
+    /// <param name="requiresExternalPeer">Whether an external peer is required.</param>
+    public NativeSctpLabProfile(bool enabled, SctpEndpoint loopbackEndpoint, bool requiresExternalPeer)
+    {
+        Enabled = enabled;
+        LoopbackEndpoint = loopbackEndpoint ?? throw new ArgumentNullException(nameof(loopbackEndpoint));
+        RequiresExternalPeer = requiresExternalPeer;
+    }
+
+    /// <summary>Whether the profile is enabled.</summary>
+    public bool Enabled { get; }
+
+    /// <summary>The loopback SCTP endpoint.</summary>
+    public SctpEndpoint LoopbackEndpoint { get; }
+
+    /// <summary>Whether an external peer is required.</summary>
+    public bool RequiresExternalPeer { get; }
+
+    /// <summary>Formats a compact lab profile summary.</summary>
+    /// <returns>The lab profile summary.</returns>
+    public string Describe()
+    {
+        return $"enabled={Enabled} loopback={LoopbackEndpoint} externalPeer={RequiresExternalPeer}";
+    }
+}
+
+/// <summary>
+/// Provides native SCTP lab profile helpers.
+/// </summary>
+public static class NativeSctpLab
+{
+    /// <summary>Creates the current native SCTP lab profile from environment variables.</summary>
+    /// <returns>The native SCTP lab profile.</returns>
+    public static NativeSctpLabProfile CreateFromEnvironment()
+    {
+        bool enabled = string.Equals(
+            Environment.GetEnvironmentVariable(NativeSctpLabProfile.EnableEnvironmentVariable),
+            "1",
+            StringComparison.Ordinal);
+
+        return new(
+            enabled,
+            new SctpEndpoint("127.0.0.1", 2905),
+            requiresExternalPeer: false);
+    }
+}