/// <summary>
/// Handle an InitialPacket to create a new QuicConnection related to this packet.
/// </summary>
/// <param name="packet">The packet received</param>
/// <param name="client">The client that sent the packet</param>
private void HandleInitialPacket(InitialPacket packet, IPEndPoint client)
{
InitialPacket incomingPacket = packet as InitialPacket;
incomingPacket.DecodeFrames();
// Create random connection ID and use it as SCID for server -> client communications
// Make sure it's not already in use
byte[] connID = new byte[8];
do
{
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
rng.GetBytes(connID);
} while (_connectionPool.Find(connID) != null);
QuicConnection qc = new QuicConnection(_server, client, connID, incomingPacket.SCID);
_connectionPool.AddConnection(qc, connID);
InitialPacket responsePacket = new InitialPacket(incomingPacket.SCID, connID, 0);
responsePacket.AddFrame(new PaddingFrame());
byte[] b = responsePacket.Encode();
_server.Send(b, b.Length, client);
Logger.Write($"Connection established. This is server {BitConverter.ToString(connID)} connected to client {BitConverter.ToString(incomingPacket.SCID)}");
}
/// <summary>
/// Connect to a remote server.
/// </summary>
/// <param name="ip">Ip of the remote server</param>
/// <param name="port">Port of the remote server</param>
public void Connect(string ip, int port)
{
// Create random DCID and SCID
byte[] DCID = new byte[8];
byte[] SCID = new byte[8];
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
rng.GetBytes(DCID);
rng.GetBytes(SCID);
// Create and send an InitialPacket to open a connection with the remote server
InitialPacket initialPacket = new InitialPacket(DCID, SCID, _packetNumber++);
byte[] byteInitialPacket = initialPacket.Encode();
_client.Send(byteInitialPacket, byteInitialPacket.Length, ip, port);
IPEndPoint server = null;
Packet packet = Packet.Unpack(_client.Receive(ref server));
// Start the connection with an InitialPacket
if (packet.GetType() == typeof(InitialPacket))
{
packet.DecodeFrames();
Logger.Write($"Data received from server {server.Address}:{server.Port}");
InitialPacket initPack = packet as InitialPacket;
Logger.Write($"Connection established. This is client {BitConverter.ToString(initPack.DCID)} connected to server {BitConverter.ToString(initPack.SCID)}");
_connection = new QuicConnection(_client, server, initPack.DCID, initPack.SCID);
}
// Background task to receive packets from the remote server
_receiveToken = new CancellationTokenSource();
_receiveTask = Task.Run(() => Receive(server), _receiveToken.Token);
}
private static int _packetHeaderSize = 4; // In bytes
/// <summary>
/// Factory that creates the correct Packet type according to the payload
/// Decode the received payload
/// </summary>
/// <param name="data">The raw packet received</param>
/// <returns>The decoded packet</returns>
public static Packet Unpack(byte[] data)
{
if (data.Length < _packetHeaderSize)
{
throw new CorruptedPacketException("Wrong header size");
}
Packet p;
// Short header packets starts with the bits | 0 | 1 |
if (!BitUtils.ReadBit(0, data))
{
// Short Header Packet
p = new ShortHeaderPacket();
if (!BitUtils.ReadBit(1, data))
{
throw new CorruptedPacketException("Wrong second bit when decoding a ShortHeaderPacket");
}
p.Decode(data);
}
// Long header packets starts with the bits | 1 | 1 |
else
{
// Long Header Packet
if (!BitUtils.ReadBit(1, data))
{
throw new CorruptedPacketException("Undefined packet header");
}
// The two next bits describe the type of the Long Header Packet
switch (BitUtils.ReadNBits(2, data, 2))
{
case 0:
p = new InitialPacket();
break;
case 1:
p = new RTTPacket();
break;
case 2:
p = new HandshakePacket();
break;
case 3:
p = new RetryPacket();
break;
default:
throw new ArgumentException("2 Bit-encoded uint is not amongst {0, 1, 2, 3}");
}
p.Decode(data);
}
return(p);
}
