public void Teardown()
{
Incoming?.Dispose();
Outgoing?.Dispose();
}
static async ReusableTask <EncryptorResult> DoCheckIncomingConnectionAsync(IPeerConnection connection, IList <EncryptionType> preferredEncryption, InfoHash[] sKeys, Factories factories)
{
bool supportsRC4Header = preferredEncryption.Contains(EncryptionType.RC4Header);
bool supportsRC4Full = preferredEncryption.Contains(EncryptionType.RC4Full);
bool supportsPlainText = preferredEncryption.Contains(EncryptionType.PlainText);
// If the connection is incoming, receive the handshake before
// trying to decide what encryption to use
using (NetworkIO.BufferPool.Rent(HandshakeMessage.HandshakeLength, out Memory <byte> buffer)) {
await NetworkIO.ReceiveAsync(connection, buffer, null, null, null).ConfigureAwait(false);
var message = new HandshakeMessage(buffer.Span);
if (message.ProtocolString == Constants.ProtocolStringV100)
{
if (supportsPlainText)
{
return(new EncryptorResult(PlainTextEncryption.Instance, PlainTextEncryption.Instance, message));
}
}
else if (supportsRC4Header || supportsRC4Full)
{
// The data we just received was part of an encrypted handshake and was *not* the BitTorrent handshake
// First switch to the threadpool as creating encrypted sockets runs expensive computations in the ctor
await MainLoop.SwitchToThreadpool();
using var encSocket = new PeerBEncryption(factories, sKeys, preferredEncryption);
await encSocket.HandshakeAsync(connection, buffer).ConfigureAwait(false);
if (encSocket.Decryptor is RC4Header && !supportsRC4Header)
{
throw new EncryptionException("Decryptor was RC4Header but that is not allowed");
}
if (encSocket.Decryptor is RC4 && !supportsRC4Full)
{
throw new EncryptionException("Decryptor was RC4Full but that is not allowed");
}
// As the connection was encrypted, the data we got from the initial Receive call will have
// been consumed during the crypto handshake process. Now that the encrypted handshake has
// been established, we should ensure we read the data again.
Memory <byte> data = encSocket.InitialData?.Length > 0 ? encSocket.InitialData : default;
if (data.IsEmpty)
{
await NetworkIO.ReceiveAsync(connection, buffer, null, null, null).ConfigureAwait(false);
encSocket.Decryptor !.Decrypt(buffer.Span);
data = buffer;
}
message.Decode(data.Span);
if (message.ProtocolString == Constants.ProtocolStringV100)
{
return(new EncryptorResult(encSocket.Decryptor !, encSocket.Encryptor !, message));
}
}
}
connection.Dispose();
throw new EncryptionException("Invalid handshake received and no decryption works");
}
