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Switch to MTProto Intermediate transport protocol (more lightweight/adequate for TCP)

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Wizou 2021-09-17 03:44:52 +02:00
parent a403a462db
commit 661b5223ac
2 changed files with 13 additions and 33 deletions
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40
src/Client.cs
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@ -15,6 +15,9 @@ using System.Threading.Tasks;
using TL;
using static WTelegram.Encryption;
// necessary for .NET Standard 2.0 compilation:
#pragma warning disable CA1835 // Prefer the 'Memory'-based overloads for 'ReadAsync' and 'WriteAsync'
namespace WTelegram
{
public sealed partial class Client : IDisposable
@ -27,9 +30,9 @@ namespace WTelegram
private readonly int _apiId;
private readonly string _apiHash;
private readonly Session _session;
private static readonly byte[] IntermediateHeader = new byte[4] { 0xee, 0xee, 0xee, 0xee };
private TcpClient _tcpClient;
private NetworkStream _networkStream;
private int _frame_seqTx = 0, _frame_seqRx = 0;
private ITLFunction _lastSentMsg;
private long _lastRecvMsgId;
private readonly List<long> _msgsToAck = new();
@ -119,7 +122,7 @@ namespace WTelegram
_tcpClient = new TcpClient(endpoint.AddressFamily);
await _tcpClient.ConnectAsync(endpoint.Address, endpoint.Port);
_networkStream = _tcpClient.GetStream();
_frame_seqTx = _frame_seqRx = 0;
await _networkStream.WriteAsync(IntermediateHeader, 0, 4);
_cts = new();
_reactorTask = Reactor(_networkStream, _cts);
_sendSemaphore.Release();
@ -316,33 +319,20 @@ namespace WTelegram
}
private async Task<byte[]> RecvFrameAsync(NetworkStream stream, CancellationToken ct)
private static async Task<byte[]> RecvFrameAsync(NetworkStream stream, CancellationToken ct)
{
byte[] frame = new byte[8];
if (await FullReadAsync(stream, frame, 8, ct) != 8)
throw new ApplicationException("Could not read frame prefix : Connection shut down");
int length = BinaryPrimitives.ReadInt32LittleEndian(frame) - 12;
byte[] overhead = new byte[4];
if (await FullReadAsync(stream, overhead, 4, ct) != 4)
throw new ApplicationException("Could not read payload length : Connection shut down");
int length = BinaryPrimitives.ReadInt32LittleEndian(overhead);
if (length <= 0 || length >= 0x10000)
throw new ApplicationException("Invalid frame_len");
int seqno = BinaryPrimitives.ReadInt32LittleEndian(frame.AsSpan(4));
if (seqno != _frame_seqRx++)
{
Trace.TraceWarning($"Unexpected frame_seq received: {seqno} instead of {_frame_seqRx}");
_frame_seqRx = seqno + 1;
}
var payload = new byte[length];
if (await FullReadAsync(stream, payload, length, ct) != length)
throw new ApplicationException("Could not read frame data : Connection shut down");
uint crc32 = Compat.UpdateCrc32(0, frame, 0, 8);
crc32 = Compat.UpdateCrc32(crc32, payload, 0, payload.Length);
if (await FullReadAsync(stream, frame, 4, ct) != 4)
throw new ApplicationException("Could not read frame CRC : Connection shut down");
if (crc32 != BinaryPrimitives.ReadUInt32LittleEndian(frame))
throw new ApplicationException("Invalid envelope CRC32");
return payload;
}
#pragma warning disable CA1835 // necessary for .NET Standard 2.0 compilation
private static async Task<int> FullReadAsync(Stream stream, byte[] buffer, int length, CancellationToken ct = default)
{
for (int offset = 0; offset != length;)
@ -369,8 +359,7 @@ namespace WTelegram
{
using var memStream = new MemoryStream(1024);
using var writer = new BinaryWriter(memStream, Encoding.UTF8);
writer.Write(0); // int32 frame_len (to be patched with full frame length)
writer.Write(_frame_seqTx++); // int32 frame_seq
writer.Write(0); // int32 payload_len (to be patched with payload length)
if (_session.AuthKeyID == 0) // send unencrypted message
{
@ -425,12 +414,10 @@ namespace WTelegram
}
var buffer = memStream.GetBuffer();
int frameLength = (int)memStream.Length;
BinaryPrimitives.WriteInt32LittleEndian(buffer, frameLength + 4); // patch frame_len with correct value
uint crc = Compat.UpdateCrc32(0, buffer, 0, frameLength);
writer.Write(crc); // int32 frame_crc
BinaryPrimitives.WriteInt32LittleEndian(buffer, frameLength - 4); // patch payload_len with correct value
//TODO: support Transport obfuscation?
await _networkStream.WriteAsync(memStream.GetBuffer(), 0, frameLength + 4);
await _networkStream.WriteAsync(memStream.GetBuffer(), 0, frameLength);
_lastSentMsg = func;
}
finally
@ -439,7 +426,6 @@ namespace WTelegram
}
return msgId;
}
#pragma warning restore CA1835
private static ITLFunction MakeFunction(ITLObject msg)
=> writer =>

6
src/Compat.cs
View file

@ -9,12 +9,6 @@ namespace WTelegram
{
static class Compat
{
// see also https://github.com/dotnet/runtime/issues/2036 and https://github.com/dotnet/runtime/pull/53623
internal static readonly Func<uint, byte[], int, int, uint> UpdateCrc32 = (Func<uint, byte[], int, int, uint>)
typeof(System.IO.Compression.ZipArchive).Assembly.GetType("System.IO.Compression.Crc32Helper")
.GetMethod("UpdateCrc32", new[] { typeof(uint), typeof(byte[]), typeof(int), typeof(int) })
.CreateDelegate(typeof(Func<uint, byte[], int, int, uint>));
#if NETCOREAPP2_1_OR_GREATER
internal static IPEndPoint IPEndPoint_Parse(string addr) => IPEndPoint.Parse(addr);
internal static BigInteger BigEndianInteger(byte[] value) => new(value, true, true);