private Tuple <byte[], ulong, int> DecodeMessage(byte[] body)
{
byte[] message;
ulong remoteMessageId;
int remoteSequence;
using (var inputStream = new MemoryStream(body))
using (var inputReader = new BinaryReader(inputStream))
{
if (inputReader.BaseStream.Length < 8)
{
throw new InvalidOperationException($"Can't decode packet");
}
ulong remoteAuthKeyId = inputReader.ReadUInt64(); // TODO: check auth key id
byte[] msgKey = inputReader.ReadBytes(16); // TODO: check msg_key correctness
AESKeyData keyData = Helpers.CalcKey(_session.AuthKey.Data, msgKey, false);
byte[] plaintext = AES.DecryptAES(keyData, inputReader.ReadBytes((int)(inputStream.Length - inputStream.Position)));
logger.Debug(Sniffer.MessageIn(plaintext));
using (MemoryStream plaintextStream = new MemoryStream(plaintext))
using (BinaryReader plaintextReader = new BinaryReader(plaintextStream))
{
var remoteSalt = plaintextReader.ReadUInt64();
var remoteSessionId = plaintextReader.ReadUInt64();
remoteMessageId = plaintextReader.ReadUInt64();
remoteSequence = plaintextReader.ReadInt32();
int msgLen = plaintextReader.ReadInt32();
message = plaintextReader.ReadBytes(msgLen);
}
}
return(new Tuple <byte[], ulong, int>(message, remoteMessageId, remoteSequence));
}
public async Task Send(byte[] packet, TeleSharp.TL.TLMethod request)
{
request.MessageId = _session.GetNewMessageId();
byte[] msgKey;
byte[] ciphertext;
using (MemoryStream plaintextPacket = makeMemory(8 + 8 + 8 + 4 + 4 + packet.Length))
{
using (BinaryWriter plaintextWriter = new BinaryWriter(plaintextPacket))
{
plaintextWriter.Write(_session.Salt);
plaintextWriter.Write(_session.Id);
plaintextWriter.Write(request.MessageId);
plaintextWriter.Write(GenerateSequence(request.Confirmed));
plaintextWriter.Write(packet.Length);
plaintextWriter.Write(packet);
var buffer = plaintextPacket.GetBuffer();
logger.Debug("Send {0} {1:x8} {2}", request, request.Constructor, Sniffer.MessageOut(buffer));
msgKey = Helpers.CalcMsgKey(buffer);
ciphertext = AES.EncryptAES(Helpers.CalcKey(_session.AuthKey.Data, msgKey, true), plaintextPacket.GetBuffer());
}
}
using (MemoryStream ciphertextPacket = makeMemory(8 + 16 + ciphertext.Length))
{
using (BinaryWriter writer = new BinaryWriter(ciphertextPacket))
{
writer.Write(_session.AuthKey.Id);
writer.Write(msgKey);
writer.Write(ciphertext);
await _transport.Send(ciphertextPacket.GetBuffer());
}
}
}
