Detect whether AES GCM encryption is supported before using it and fallback to XChaCha20Poly1305RtpSizeEncryption if needed (#364)

Author: KubaZ2

NetCord/Gateway/Voice/Encryption/Aes256GcmRtpSizeEncryption.cs

@@ -11,6 +11,8 @@ public sealed class Aes256GcmRtpSizeEncryption : IVoiceEncryption
 
     private const int TagSize = 16;
 
+    public static bool IsSupported => AesGcm.IsSupported;
+
     public string Name => "aead_aes256_gcm_rtpsize";
 
     public int Expansion => TagSize + sizeof(int);

NetCord/Gateway/Voice/Encryption/IVoiceEncryption.cs

@@ -5,6 +5,11 @@ namespace NetCord.Gateway.Voice.Encryption;
 /// </summary>
 public interface IVoiceEncryption : IDisposable
 {
+    /// <summary>
+    /// Indicates whether the encryption algorithm is supported on the current platform.
+    /// </summary>
+    public static abstract bool IsSupported { get; }
+
     /// <summary>
     /// The name of the encryption algorithm.
     /// </summary>

NetCord/Gateway/Voice/Encryption/XChaCha20Poly1305RtpSizeEncryption.cs

@@ -10,6 +10,8 @@ public sealed class XChaCha20Poly1305RtpSizeEncryption : IVoiceEncryption
     private byte[]? _key;
     private int _nonce;
 
+    public static bool IsSupported => true;
+
     public string Name => "aead_xchacha20_poly1305_rtpsize";
 
     public int Expansion => XChaCha20Poly1305.ABytes + sizeof(int);

NetCord/Gateway/Voice/VoiceEncryptionProvider.cs

@@ -12,7 +12,7 @@ private VoiceEncryptionProvider()
 
     public IVoiceEncryption GetEncryption(IReadOnlyList<string> modes)
     {
-        return modes.Contains("aead_aes256_gcm_rtpsize")
+        return (modes.Contains("aead_aes256_gcm_rtpsize") && Aes256GcmRtpSizeEncryption.IsSupported)
             ? new Aes256GcmRtpSizeEncryption()
             : new XChaCha20Poly1305RtpSizeEncryption();
     }