// Runs the server continuously until quit
public static void Run(FTPSocket socket)
{
var stop = false;
while (!stop)
{
stop = HandleCommand(socket);
}
}
// Main function accepts command line arguments
static void Main(string[] args)
{
Debug = false;
Passive = false;
if (args.Length == 0 || args.Length > 2)
{
Console.WriteLine("Usage: ftp <server> [port]");
return;
}
// Get host and port from arguments
var host = args[0];
var port = 21;
if (args.Length == 2)
{
int.TryParse(args[1], out port);
}
try
{
// Creates an FTP command socket and runs the command handler with it
using (var ftp = new FTPSocket(host, port))
{
FTPClient.Run(ftp);
}
}
catch (SocketException)
{
Console.WriteLine("Unable to resolve or connect to host");
}
catch (TimeoutException)
{
Console.WriteLine("421 Timeout.");
}
catch
{
Console.WriteLine("An unexpected error occurred.");
}
}
// Creates a new socket wrapper using the given command connection
public DataSocket(FTPSocket ftp)
{
if (Program.Passive)
{
// If in passive mode, send a PASV command
ftp.Write("PASV");
var(status, message) = ftp.ReadStatus();
if (status != 227)
{
Console.WriteLine(message);
return;
}
var match = Regex.Match(message, @"\((\d+,\d+,\d+,\d+),(\d+),(\d+)\)");
var address = IPAddress.Parse(match.Groups[1].Value.Replace(',', '.'));
var port = int.Parse(match.Groups[2].Value) * 256 + int.Parse(match.Groups[3].Value);
socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
socket.Connect(address, port);
}
else
{
// In in active mode, create a listening server for the connection
listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
var address = ftp.LocalIP;
listener.Bind(new IPEndPoint(address, 0));
listener.Listen(1);
var ip = address.ToString().Replace('.', ',');
var port = ((IPEndPoint)listener.LocalEndPoint).Port;
ftp.Write("PORT {0},{1},{2}", ip, port / 256, port % 256);
var(status, message) = ftp.ReadStatus();
if (status != 200)
{
throw new Exception("Data connection failed");
}
}
}
// Handles a command from the client using the given socket
static bool HandleCommand(FTPSocket socket)
{
// Writes a user prompt and extracts the command and arguments from user input
Console.Write(" > ");
var input = Console.ReadLine();
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;
}
switch (command)
{
// Sets the server to transfer in ASCII mode
case "ASCII":
socket.Write("TYPE A");
Console.WriteLine(socket.Read());
break;
// Makes the server transfer in binary mode
case "BINARY":
socket.Write("TYPE I");
Console.WriteLine(socket.Read());
break;
// Changes the server to the given directory
case "CD":
if (arguments.Length == 0)
{
Console.WriteLine(" CD requires a path argument");
break;
}
socket.Write("CWD {0}", arguments);
Console.WriteLine(socket.Read());
break;
// Navigates up one directory on the server
case "CDUP":
socket.Write("CDUP");
Console.WriteLine(socket.Read());
break;
// Endables debug mode, printing messages for each message sent over the data connection
case "DEBUG":
Program.Debug = !Program.Debug;
if (Program.Debug)
{
Console.WriteLine(" Debug mode enabled");
}
else
{
Console.WriteLine(" Debug mode disabled");
}
break;
// Prints a directory listing for the current directory
case "DIR":
using (var data = new DataSocket(socket))
{
socket.Write("LIST");
var(status2, message) = socket.ReadStatus();
Console.WriteLine(message);
if (status2 == 150)
{
Console.WriteLine(data.ReadText());
Console.WriteLine(socket.Read());
}
}
break;
// Gets the specified file from the server
case "GET":
using (var data = new DataSocket(socket))
{
socket.Write("RETR {0}", arguments);
var(status2, message) = socket.ReadStatus();
Console.WriteLine(message);
if (status2 == 150)
{
var path = arguments.Split('/');
data.ReadToFile(path[path.Length - 1]);
Console.WriteLine(socket.Read());
}
}
break;
// Prints a help message
case "HELP":
Console.WriteLine("Available commands:");
Console.WriteLine("ASCII: sets the server to ASCII transfer mode");
Console.WriteLine("BINARY: sets the server to binary transfer mode");
Console.WriteLine("CD <path>: navigates to the given path on the server");
Console.WriteLine("CDUP: naigates up one directory on the server");
Console.WriteLine("DEBUG: toggles debug mode, which prints all commands sent");
Console.WriteLine("DIR: prints a directory listing for the current server directory");
Console.WriteLine("GET <file>: downloads the specified file from the server");
Console.WriteLine("HELP: prints this help message");
Console.WriteLine("PASSIVE: toggles passive file transfer mode");
Console.WriteLine("PWD: prints the current directory from the server");
Console.WriteLine("QUIT: closes the FTP connection and exits");
break;
// Switches between passive and active transfer
case "PASSIVE":
Program.Passive = !Program.Passive;
if (Program.Passive)
{
Console.WriteLine(" Passive mode enabled");
}
else
{
Console.WriteLine(" Passive mode disabled");
}
break;
// Prints the current directory on the server
case "PWD":
socket.Write("PWD");
Console.WriteLine(socket.Read());
break;
// Quits the FTP connetion
case "QUIT":
socket.Write("QUIT");
Console.WriteLine(socket.Read());
return(true);
// Handles unknown commands
default:
Console.WriteLine(" Command not recognized");
break;
}
return(false);
}
