Cleaned up audio code

src/Discord.Net.WebSocket/Audio/Streams/SodiumEncryptStream.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Discord.Audio.Streams
+{
+    ///<summary> Encrypts an RTP frame using libsodium </summary>
+    public class SodiumEncryptStream : AudioOutStream
+    {
+        private readonly AudioOutStream _next;
+        private readonly byte[] _nonce, _secretKey;
+
+        //protected readonly byte[] _buffer;
+
+        internal SodiumEncryptStream(AudioOutStream next, byte[] secretKey/*, int bufferSize = 4000*/)
+        {
+            _next = next;
+            _secretKey = secretKey;
+            //_buffer = new byte[bufferSize]; //TODO: Can Sodium do an in-place encrypt?
+            _nonce = new byte[24];
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            WriteAsync(buffer, offset, count, CancellationToken.None).GetAwaiter().GetResult();
+        }
+        public override async Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+
+            Buffer.BlockCopy(buffer, offset, _nonce, 0, 12); //Copy nonce from RTP header
+            count = SecretBox.Encrypt(buffer, offset + 12, count - 12, buffer, 12, _nonce, _secretKey);
+            await _next.WriteAsync(buffer, 0, count + 12, cancellationToken).ConfigureAwait(false);
+        }
+
+        public override async Task FlushAsync(CancellationToken cancelToken)
+        {
+            await _next.FlushAsync(cancelToken).ConfigureAwait(false);
+        }
+        public override async Task ClearAsync(CancellationToken cancelToken)
+        {
+            await _next.ClearAsync(cancelToken).ConfigureAwait(false);
+        }
+    }
+}