Add encrypted managed UDP relay and native voice conformance

dotnet/src/VoiceCat.Server/Transport/TlsControlConnection.cs

@@ -21,6 +21,8 @@ internal sealed class TlsControlConnection : IAsyncDisposable
     private int prefixBytes;
     private byte[]? payload;
     private int payloadBytes;
+    private readonly TaskCompletionSource mediaReady = new(TaskCreationOptions.RunContinuationsAsynchronously);
+    private MediaSessionCrypto? mediaCrypto;
 
     public Task Completion { get; }
     public CancellationToken CancellationToken => lifetime.Token;
@@ -48,6 +50,12 @@ internal sealed class TlsControlConnection : IAsyncDisposable
 
     public void CompleteWrites() => outgoing.Writer.TryComplete();
 
+    internal async Task<MediaSessionCrypto> TakeMediaCryptoAsync(CancellationToken cancellationToken)
+    {
+        await mediaReady.Task.WaitAsync(cancellationToken).ConfigureAwait(false);
+        return Interlocked.Exchange(ref mediaCrypto, null) ?? throw new InvalidOperationException("Media crypto already has an owner.");
+    }
+
     private async Task RunAsync()
     {
         byte[] ciphertext = new byte[16384];
@@ -80,6 +88,13 @@ internal sealed class TlsControlConnection : IAsyncDisposable
                         break;
                     }
                     tls.ReceiveCiphertext(ciphertext.AsSpan(0, count));
+                    if (tls.IsReady && !mediaReady.Task.IsCompleted)
+                    {
+                        var encryptor = tls.CreateMediaEncryptor();
+                        try { mediaCrypto = new(encryptor, tls.CreateMediaDecryptor()); }
+                        catch { encryptor.Dispose(); throw; }
+                        mediaReady.SetResult();
+                    }
                     if (tls.IsReady) lifetime.CancelAfter(TimeSpan.FromSeconds(60));
                     while ((count = tls.ReadPlaintext(plaintext)) > 0) Parse(plaintext.AsSpan(0, count));
                     await FlushAsync(sendBuffer, cancellationToken).ConfigureAwait(false);
@@ -104,6 +119,7 @@ internal sealed class TlsControlConnection : IAsyncDisposable
         }
         finally
         {
+            mediaReady.TrySetCanceled();
             lifetime.Cancel();
             socket.Dispose();
             if (receive is not null)
@@ -163,7 +179,7 @@ internal sealed class TlsControlConnection : IAsyncDisposable
     public async ValueTask DisposeAsync()
     {
         lifetime.Cancel();
-        await Completion.ConfigureAwait(false);
-        lifetime.Dispose();
+        try { await Completion.ConfigureAwait(false); }
+        finally { Interlocked.Exchange(ref mediaCrypto, null)?.Dispose(); lifetime.Dispose(); }
     }
 }