async Task Handshake(IList <EncryptionType> outgoingEncryption, IList <EncryptionType> incomingEncryption, bool appendInitialPayload)
{
var handshakeIn = new HandshakeMessage(InfoHash, IncomingId, VersionInfo.ProtocolStringV100);
var handshakeOut = new HandshakeMessage(InfoHash, OutgoingId, VersionInfo.ProtocolStringV100);
var incomingTask = EncryptorFactory.CheckIncomingConnectionAsync(Incoming, incomingEncryption, SKeys);
var outgoingTask = EncryptorFactory.CheckOutgoingConnectionAsync(Outgoing, outgoingEncryption, InfoHash, appendInitialPayload ? handshakeOut : null);
// If the handshake was not part of the initial payload, send it now.
var outgoingCrypto = await outgoingTask;
if (!appendInitialPayload)
{
await PeerIO.SendMessageAsync(Outgoing, outgoingCrypto.Encryptor, handshakeOut, null, null, null);
}
// Receive the handshake and make sure it decrypted correctly.
var incomingCrypto = await incomingTask;
Assert.AreEqual(OutgoingId, incomingCrypto.Handshake.PeerId, "#1a");
// Send the other handshake.
await PeerIO.SendMessageAsync(Incoming, incomingCrypto.Encryptor, handshakeIn, null, null, null);
// Receive the other handshake and make sure it decrypted ok on the other side.
handshakeIn = await PeerIO.ReceiveHandshakeAsync(Outgoing, outgoingCrypto.Decryptor);
Assert.AreEqual(IncomingId, handshakeIn.PeerId, "#1b");
if (outgoingEncryption[0] == EncryptionType.PlainText)
{
// If the outgoing encryption is plain text, then the whole thing is plain text
Assert.IsInstanceOf <PlainTextEncryption> (incomingCrypto.Decryptor, "#2a");
Assert.IsInstanceOf <PlainTextEncryption> (outgoingCrypto.Decryptor, "#2b");
}
else
{
EncryptionType expected;
if (outgoingEncryption.Contains(EncryptionType.RC4Full) && outgoingEncryption.Contains(EncryptionType.RC4Header))
{
// If the outgoing encryption supports both RC4Full and RC4Header, the final type is determined by
// the priority associated with the 'Incoming' connection as it will decide between Header or Full if
// the Outgoing connection asks for both.
expected = EncryptionTypes.PreferredRC4(incomingEncryption).Value;
}
else
{
// Otherwise the outgoing encryption will specify a single RC4 type, so the incoming connection
// will either accept it or close the connection.
expected = EncryptionTypes.PreferredRC4(outgoingEncryption).Value;
}
if (expected == EncryptionType.RC4Full)
{
Assert.IsInstanceOf <RC4> (incomingCrypto.Decryptor, "#3a");
Assert.IsInstanceOf <RC4> (outgoingCrypto.Decryptor, "#3b");
}
else if (expected == EncryptionType.RC4Header)
{
Assert.IsInstanceOf <RC4Header> (incomingCrypto.Decryptor, "#4a");
Assert.IsInstanceOf <RC4Header> (outgoingCrypto.Decryptor, "#4b");
}
else
{
throw new NotSupportedException();
}
}
}
