// Creates a data connection using the given command socket, mode, and message from the client giving the port
public DataSocket(FTPSocket ftp, bool passive, string message)
{
if (passive)
{
// Establishes a server for the client to connect to in passive mode
listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
listener.Bind(new IPEndPoint(ftp.LocalIP, 0));
listener.Listen(1);
var local = (IPEndPoint)listener.LocalEndPoint;
var ip = local.Address.ToString().Replace('.', ',');
var port = local.Port;
ftp.Write("227 Entering Passive Mode ({0},{1},{2}).", ip, port / 256, port % 256);
}
else
{
// Connects to the clients data connection in active mode
var match = Regex.Match(message, @"(\d+,\d+,\d+,\d+),(\d+),(\d+)");
address = IPAddress.Parse(match.Groups[1].Value.Replace(',', '.'));
port = int.Parse(match.Groups[2].Value) * 256 + int.Parse(match.Groups[3].Value);
socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
ftp.Write("200 PORT command successful. Consider using PASV.");
}
}
// Listens and responds to commands from the client
public bool HandleCommand()
{
// Reads and extracts the command and arguments
var input = ftp.Read();
var match = Regex.Match(input, @"([^ ]+)(?: (.+))?");
var command = "";
var arguments = "";
if (match.Groups[1].Success)
{
command = match.Groups[1].Value.ToUpper();
}
if (match.Groups[2].Success)
{
arguments = match.Groups[2].Value;
}
// Stops if the client is not authenticated or authenticating
if ((!user && command != "USER") || (!pass && command != "USER" && command != "PASS"))
{
ftp.Write("530 Please login with USER and PASS.");
return(false);
}
switch (command)
{
// Moves the current path up 1 directory
case "CDUP":
path = Normalize(Path.Combine(".", path, ".."));
ftp.Write("250 Directory successfully changed.");
break;
// Moves to the specified directory
case "CWD":
if (arguments.Length > 0)
{
var temp = Path.Combine(".", path, arguments);
if (Directory.Exists(temp))
{
path = Normalize(temp);
ftp.Write("250 Directory successfully changed.");
break;
}
}
ftp.Write("550 Failed to change directory.");
break;
// Lists files in the current directory
case "LIST":
if (data == null)
{
ftp.Write("425 Use PASV or PORT first.");
break;
}
ftp.Write("150 Here comes the directory listing.");
data.SendDir(path);
ftp.Write("226 Directory send OK.");
data = null;
break;
// Accepts a password from the client
case "PASS":
ftp.Write("230 Login successful.");
pass = true;
break;
// Sets up a passive mode data connection
case "PASV":
data = new DataSocket(ftp, true, null);
break;
// Sets up an active mode data connection
case "PORT":
data = new DataSocket(ftp, false, arguments);
break;
// Prints the working directory to the client
case "PWD":
ftp.Write("257 \"{0}\"", path);
break;
// Lets the client quit the connection
case "QUIT":
ftp.Write("221 Goodbye.");
return(true);
// Sends a file back to the client
case "RETR":
if (data == null)
{
ftp.Write("425 Use PASV or PORT first.");
break;
}
var file = Path.GetRelativePath(".", Path.Combine(path, arguments));
if (!File.Exists(file))
{
ftp.Write("550 Failed to open file.");
break;
}
ftp.Write("150 Opening BINARY mode data connection for {0}", arguments);
data.SendFile(file);
ftp.Write("226 Transfer complete.");
data = null;
break;
// Sets the file transfer encoding
case "TYPE":
if (arguments == "I")
{
ftp.Write("200 Switching to Binary mode.");
break;
}
ftp.Write("200 Only Binary mode is supported.");
break;
// Accepts usernames for authentication
case "USER":
if (arguments == "ftp" || arguments == "anonymous")
{
ftp.Write("331 Please specify the password.");
user = true;
break;
}
ftp.Write("530 This FTP server is anonymous only.");
break;
// Handles unknown commands
default:
ftp.Write("200 Command not supported.");
break;
}
return(false);
}
