public BufLen GenerateData(I2NPMessage msg)
{
if (NTCPContext == null)
{
throw new Exception("NTCP Session not negotiated!");
}
if (NTCPContext.Encryptor == null)
{
throw new Exception("NTCP encryptor not available");
}
var data = msg != null ? msg.Header16.HeaderAndPayload: null;
var datalength = msg == null ? 4 : data.Length;
var buflen = 2 + datalength + 4;
var padlength = BufUtils.Get16BytePadding(buflen);
buflen += padlength;
var buf = new BufLen(new byte[buflen]);
var writer = new BufRefLen(buf);
// Length
if (msg == null)
{
// Send timestamp
writer.Write16(0);
writer.WriteFlip32((uint)(DateTime.UtcNow - I2PDate.RefDate).TotalSeconds);
}
else
{
if (data.Length > 16378)
{
throw new ArgumentException("NTCP data can be max 16378 bytes long!");
}
writer.WriteFlip16((ushort)data.Length);
writer.Write(data);
}
// Pad
writer.Write(BufUtils.Random(writer.Length - 4));
// Checksum
var checkbuf = new BufLen(buf, 0, writer - buf);
var checksum = LZUtils.Adler32(1, checkbuf);
writer.WriteFlip32(checksum);
// Encrypt
NTCPContext.Encryptor.ProcessBytes(buf);
return(buf);
}
private BufLen ReadBlock()
{
var inbufend = 2 + BlockLength + 4;
inbufend += BufUtils.Get16BytePadding(inbufend);
while (InBufPos < inbufend)
{
if (MySocket.Available > 0)
{
var len = MySocket.Receive(InBuf, InBufPos, inbufend - InBufPos, SocketFlags.None);
if (len == 0)
{
throw new EndOfStreamEncounteredException();
}
InBufPos += len;
}
else
{
Thread.Sleep(400);
if (!MySocket.Connected)
{
throw new EndOfStreamEncounteredException();
}
}
}
Cipher.ProcessBytes(new BufLen(InBuf, 16, InBufPos - 16));
var checksum = LZUtils.Adler32(1, new BufLen(InBuf, 0, InBufPos - 4));
var blocksum = BufUtils.Flip32(InBuf, InBufPos - 4);
if (checksum != blocksum)
{
throw new ChecksumFailureException("NTCPReader: Received Adler checksum mismatch.");
}
var result = new BufLen(InBuf, 2, BlockLength);
BlockLength = -1;
#if LOG_ALL_TRANSPORT
Logging.LogTransport(string.Format("NTCPReader +{1}+ block received: {0} bytes [0x{0:X}]", result.Length, Context.TransportInstance));
#endif
return(result.Clone());
}