protected void AcceptCallback(IAsyncResult result)
{
var listener = result.AsyncState as Socket;
var handler = listener.EndAccept(result);
handler.Send(this.welcomeMessage);
ClientConnectionState state = new ClientConnectionState(handler);
handler.BeginReceive(
state.Buffer,
0,
handler.Available <= 64000 ? handler.Available : 64000,
0,
new AsyncCallback(ReadCallback),
state
);
}
protected void DecodeMessage(ClientConnectionState state)
{
if (state.Buffer.Length < 2)
{
throw new InvalidOperationException("ERROR DECODE Buffer length is invalid");
}
string msg = Encoding.ASCII.GetString(state.Buffer, 0, Math.Min(10, state.Buffer.Length));
IPAddress ip = (state.Socket.RemoteEndPoint as IPEndPoint).Address ?? null;
/* Protocol reading section */
if (msg.StartsWith("LOGIN ")) // Connecting to server
{
msg = Encoding.ASCII.GetString(state.Buffer, 6, Math.Min(300, state.Buffer.Length));
string[] arguments = msg.Split(' ');
if (arguments.Length != 4 || arguments[0] != "HOST" || arguments[2] != "PASS")
{
state.Buffer = null;
state.Socket.Send(this.invalidMessage);
}
string host = arguments[1];
string pass = arguments[3];
if (pass.Length != 8 || pass != CurrentPassword)
{
state.Buffer = null;
state.Socket.Send(Encoding.ASCII.GetBytes("INVALID PASS"));
}
CurrentPassword = GeneratePassword();
ClientConnectedEventArgs e = new ClientConnectedEventArgs();
e.Server = this;
e.UtcTime = DateTime.UtcNow;
state.Password = e.Password = pass;
e.Hostname = host;
state.ClientId = e.ClientId = Guid.NewGuid();
e.IP = ip;
OnClientConnected?.Invoke(this, e);
}
else if (msg.StartsWith("FILE ADD\0")) // Start new file transfer
{
ReadonlyStream stream = new ReadonlyStream(state.Buffer);
stream.Position = 9;
using (BinaryReader reader = new BinaryReader(stream))
{
try
{
Guid clientid = new Guid(reader.ReadBytes(16));
Client client = ConnectedClients.Where(item => item.Id == clientid && item.IP == ip).First();
if (client is null)
{
state.Buffer = null;
state.Socket.Send(Encoding.ASCII.GetBytes("ABORTED"));
}
if (reader.ReadByte() != 0)
{
state.Buffer = null;
state.Socket.Send(Encoding.ASCII.GetBytes("INVALID MESSAGE"));
}
string filename = string.Empty;
char c;
while ((c = reader.ReadChar()) != 0)
{
filename += c;
}
ulong size = reader.ReadUInt64();
TransferRequestEventArgs e = new TransferRequestEventArgs();;
e.Client = client;
e.Filename = filename;
e.Id = Guid.NewGuid();
e.Server = this;
e.Size = size;
e.UtcTime = DateTime.UtcNow;
OnTransferRequest?.Invoke(this, e);
e.Server = this;
if (!e.IsAccepted || e.IsCanceled)
{
}
if (e.Stream is null || !e.Stream.CanWrite)
{
}
}
catch (EndOfStreamException)
{
state.Buffer = null;
state.Socket.Send(Encoding.ASCII.GetBytes("INVALID MESSAGE"));
}
}
}
else if (msg.StartsWith("FILE STOP\0")) // Abort file transfer
{
}
else if (msg.StartsWith("FILE DATA\0")) // Set data block of file
{
}
else if (msg.StartsWith("LOGOUT\0")) // Close connection
{
}
else // Invalid message
{
state.Buffer = null;
state.Socket.Send(this.invalidMessage);
}
}