report a peer's port change locally without rewriting it

Keep IConfigurationManager source-compatible for plugin implementers.

tests/Jellyfin.Server.Implementations.Tests/Configuration/ApplicationHostPortChangeTests.cs

@@ -0,0 +1,81 @@
+using Emby.Server.Implementations;
+using Xunit;
+
+namespace Jellyfin.Server.Implementations.Tests.Configuration;
+
+/// <summary>
+/// The decision <c>ApplicationHost.OnConfigurationUpdated</c> makes about a port change. The ports this
+/// process bound are fixed for its lifetime and the pending-restart flag is per-process, so an instance
+/// applying another instance's port change still has to notice its own binding went stale - while leaving
+/// the authorization write, and the notice that follows it, to the instance that made the change.
+/// </summary>
+public static class ApplicationHostPortChangeTests
+{
+    /// <summary>
+    /// The local case, unchanged: clear the authorization flag and report the pending restart.
+    /// </summary>
+    [Fact]
+    public static void LocalPortChange_ClearsAuthorizationAndRequiresRestart()
+    {
+        var outcome = ApplicationHost.EvaluatePortChange(8096, 8920, 9096, 8920, true, false);
+
+        Assert.True(outcome.RequiresRestart);
+        Assert.True(outcome.ClearsPortAuthorization);
+    }
+
+    /// <summary>
+    /// The cross-instance case: the peer wrote the new port and cleared the flag with it, so this
+    /// instance must not write, but it is still listening on the old port and has to say so.
+    /// </summary>
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public static void RemotePortChange_RequiresRestartWithoutWriting(bool isPortAuthorized)
+    {
+        var outcome = ApplicationHost.EvaluatePortChange(8096, 8920, 9096, 8920, isPortAuthorized, true);
+
+        Assert.True(outcome.RequiresRestart);
+        Assert.False(outcome.ClearsPortAuthorization);
+    }
+
+    /// <summary>
+    /// A second update while a port change is already pending must not write the flag again, and the
+    /// binding is still stale.
+    /// </summary>
+    [Fact]
+    public static void LocalPortChange_WithAuthorizationAlreadyCleared_RequiresRestartWithoutWriting()
+    {
+        var outcome = ApplicationHost.EvaluatePortChange(8096, 8920, 9096, 8920, false, false);
+
+        Assert.True(outcome.RequiresRestart);
+        Assert.False(outcome.ClearsPortAuthorization);
+    }
+
+    /// <summary>
+    /// An update that leaves the ports alone is not a port change, whoever wrote it.
+    /// </summary>
+    [Theory]
+    [InlineData(false)]
+    [InlineData(true)]
+    public static void UnchangedPorts_DoNothing(bool isApplyingRemoteInvalidation)
+    {
+        var outcome = ApplicationHost.EvaluatePortChange(8096, 8920, 8096, 8920, true, isApplyingRemoteInvalidation);
+
+        Assert.False(outcome.RequiresRestart);
+        Assert.False(outcome.ClearsPortAuthorization);
+    }
+
+    /// <summary>
+    /// Nothing is decided before the ports have been bound.
+    /// </summary>
+    [Theory]
+    [InlineData(0, 8920)]
+    [InlineData(8096, 0)]
+    public static void UnboundPorts_DoNothing(int boundHttpPort, int boundHttpsPort)
+    {
+        var outcome = ApplicationHost.EvaluatePortChange(boundHttpPort, boundHttpsPort, 9096, 9920, true, false);
+
+        Assert.False(outcome.RequiresRestart);
+        Assert.False(outcome.ClearsPortAuthorization);
+    }
+}