Getting Error in Login() method in FtpConnection Class

[ruju00]

I am getting an error in Login() method of the following class
FtpConnection

public class FtpConnection
{
public class FtpException : Exception
{
public FtpException(string message) : base(message){}
public FtpException(string message, Exception innerException) :
base(message,innerException){}
}

private static int BUFFER_SIZE = 512;
private static Encoding ASCII = Encoding.ASCII;

private bool verboseDebugging = false;

private string server = "localhost";
//private string server = "81.19.59.132";
private string remotePath = ".";
private string username = "anonymous";
private string password = "an*******@anonymous.net";
private string message = null;
private string result = null;

private int port = 21;
private int bytes = 0;
private int resultCode = 0;

private bool loggedin = false;
private bool binMode = false;

private Byte[] buffer = new Byte[BUFFER_SIZE];
private Socket clientSocket = null;

private int timeoutSeconds = 10;

public FtpConnection()
{

}

public FtpConnection(string server, string username, string password)
{
this.server = server;
this.username = username;
this.password = password;
}

public FtpConnection(string server, string username, string password,
int timeoutSeconds, int port)
{
this.server = server;
this.username = username;
this.password = password;
this.timeoutSeconds = timeoutSeconds;
this.port = port;
}

// Display all communications to the debug log
public bool VerboseDebugging
{
get
{
return this.verboseDebugging;
}
set
{
this.verboseDebugging = value;
}
}

// Remote server port. Typically TCP 21

public int Port
{
get
{
return this.port;
}
set
{
this.port = value;
}
}

// Timeout waiting for a response from server, in seconds.

public int Timeout
{
get
{
return this.timeoutSeconds;
}
set
{
this.timeoutSeconds = value;
}
}

// Gets and Sets the name of the FTP server.

public string Server
{
get
{
return this.server;
}
set
{
this.server = value;
}
}

// Gets and Sets the port number.

public int RemotePort
{
get
{
return this.port;
}
set
{
this.port = value;
}
}

// GetS and Sets the remote directory.

public string RemotePath
{
get
{
return this.remotePath;
}
set
{
this.remotePath = value;
}

}

// Gets and Sets the username.

public string Username
{
get
{
return this.username;
}
set
{
this.username = value;
}
}

// Gets and Set the password.

public string Password
{
get
{
return this.password;
}
set
{
this.password = value;
}
}

// If the value of mode is true, set binary mode for downloads,
else, Ascii mode.

public bool BinaryMode
{
get
{
return this.binMode;
}
set
{
if ( this.binMode == value ) return;

if ( value )
sendCommand("TYPE I");

else
sendCommand("TYPE A");

if ( this.resultCode != 200 ) throw new
FtpException(result.Substring(4));
}
}

// Login to the remote server.

public void Login()
{
if (this.loggedin) this.Close();

Debug.WriteLine("Opening connection to " + this.server, "FtpClient"
);

IPAddress addr = null;
IPEndPoint ep = null;

try
{
this.clientSocket = new Socket( AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp );
addr = Dns.Resolve(this.server).AddressList[0];
ep = new IPEndPoint( addr, this.port );
this.clientSocket.Connect(ep);
}
catch(Exception ex)
{
if ( this.clientSocket != null && this.clientSocket.Connected )
this.clientSocket.Close();

throw new FtpException("Couldn't connect to remote server",ex);
}

this.readResponse();

if(this.resultCode != 220)
{
this.Close();
throw new FtpException(this.result.Substring(4));
}

this.sendCommand( "USER " + username );

if( !(this.resultCode == 331 || this.resultCode == 230) )
{
this.cleanup();
throw new FtpException(this.result.Substring(4));
}

if( this.resultCode != 230 )
{
this.sendCommand( "PASS " + password );

if( !(this.resultCode == 230 || this.resultCode == 202) )
{
this.cleanup();
throw new FtpException(this.result.Substring(4));
}
}

this.loggedin = true;

Debug.WriteLine( "Connected to " + this.server, "FtpClient" );

this.ChangeDir(this.remotePath);
}

// Close the FTP connection.

public void Close()
{
Debug.WriteLine("Closing connection to " + this.server, "FtpClient"
);

if( this.clientSocket != null )
{
this.sendCommand("QUIT");
}

this.cleanup();
}

// Return a string array containing the remote directory's file
list.

public string[] GetFileList()
{
return this.GetFileList("*.*");
}

// Return a string array containing the remote directory's file
list.

public string[] GetFileList(string mask)
{
if ( !this.loggedin ) this.Login();

Socket cSocket = createDataSocket();

this.sendCommand("NLST " + mask);

if(!(this.resultCode == 150 || this.resultCode == 125)) throw new
FtpException(this.result.Substring(4));

this.message = "";

DateTime timeout = DateTime.Now.AddSeconds(this.timeoutSeconds);

while( timeout > DateTime.Now )
{
int bytes = cSocket.Receive(buffer, buffer.Length, 0);
this.message += ASCII.GetString(buffer, 0, bytes);

if ( bytes < this.buffer.Length ) break;
}

string[] msg = this.message.Replace("\r","").Split('\n');

cSocket.Close();

if ( this.message.IndexOf( "No such file or directory" ) != -1 )
msg = new string[]{};

this.readResponse();

if ( this.resultCode != 226 )
msg = new string[]{};
// throw new FtpException(result.Substring(4));
return msg;
}

// Return the size of a file.

public long GetFileSize(string fileName)
{
if ( !this.loggedin ) this.Login();

this.sendCommand("SIZE " + fileName);
long size=0;

if ( this.resultCode == 213 )
size = long.Parse(this.result.Substring(4));

else
throw new FtpException(this.result.Substring(4));

return size;
}

// Download a file to the Assembly's local directory,
// keeping the same file name.

public void Download(string remFileName)
{
this.Download(remFileName,"",false);
}

// Download a remote file to the Assembly's local directory,
// keeping the same file name, and set the resume flag.

public void Download(string remFileName,Boolean resume)
{
this.Download(remFileName,"",resume);
}

// Download a remote file to a local file name which can include
// a path. The local file name will be created or overwritten,
// but the path must exist.

public void Download(string remFileName,string locFileName)
{
this.Download(remFileName,locFileName,false);
}

// Download a remote file to a local file name which can include
// a path, and set the resume flag. The local file name will be
// created or overwritten, but the path must exist.

public void Download(string remFileName,string locFileName,Boolean
resume)
{
if ( !this.loggedin ) this.Login();

this.BinaryMode = true;

Debug.WriteLine("Downloading file " + remFileName + " from " +
server + "/" + remotePath, "FtpClient" );

if (locFileName.Equals(""))
{
locFileName = remFileName;
}

FileStream output = null;

if ( !File.Exists(locFileName) )
output = File.Create(locFileName);

else
output = new FileStream(locFileName,FileMode.Open);

Socket cSocket = createDataSocket();

long offset = 0;

if ( resume )
{
offset = output.Length;

if ( offset > 0 )
{
this.sendCommand( "REST " + offset );
if ( this.resultCode != 350 )
{
//Server dosnt support resuming
offset = 0;
Debug.WriteLine("Resuming not supported:" + result.Substring(4),
"FtpClient" );
}
else
{
Debug.WriteLine("Resuming at offset " + offset, "FtpClient" );
output.Seek( offset, SeekOrigin.Begin );
}
}
}

this.sendCommand("RETR " + remFileName);

if ( this.resultCode != 150 && this.resultCode != 125 )
{
throw new FtpException(this.result.Substring(4));
}

DateTime timeout = DateTime.Now.AddSeconds(this.timeoutSeconds);

while ( timeout > DateTime.Now )
{
this.bytes = cSocket.Receive(buffer, buffer.Length, 0);
output.Write(this.buffer,0,this.bytes);

if ( this.bytes <= 0)
{
break;
}
}

output.Close();

if ( cSocket.Connected ) cSocket.Close();

this.readResponse();

if( this.resultCode != 226 && this.resultCode != 250 )
throw new FtpException(this.result.Substring(4));
}

// Upload a file.

public void Upload(string fileName)
{
this.Upload(fileName,false);
}

// Upload a file and set the resume flag.

public void Upload(string fileName, bool resume)
{
if ( !this.loggedin ) this.Login();

Socket cSocket = null ;
long offset = 0;

if ( resume )
{
try
{
this.BinaryMode = true;

offset = GetFileSize( Path.GetFileName(fileName) );
}
catch(Exception)
{
// file not exist
offset = 0;
}
}

// open stream to read file
FileStream input = new FileStream(fileName,FileMode.Open);

if ( resume && input.Length < offset )
{
// different file size
Debug.WriteLine("Overwriting " + fileName, "FtpClient");
offset = 0;
}
else if ( resume && input.Length == offset )
{
// file done
input.Close();
Debug.WriteLine("Skipping completed " + fileName + " - turn resume
off to not detect.", "FtpClient");
return;
}

// dont create untill we know that we need it
cSocket = this.createDataSocket();

if ( offset > 0 )
{
this.sendCommand( "REST " + offset );
if ( this.resultCode != 350 )
{
Debug.WriteLine("Resuming not supported", "FtpClient");
offset = 0;
}
}

this.sendCommand( "STOR " + Path.GetFileName(fileName) );

if ( this.resultCode != 125 && this.resultCode != 150 ) throw new
FtpException(result.Substring(4));

if ( offset != 0 )
{
Debug.WriteLine("Resuming at offset " + offset, "FtpClient" );

input.Seek(offset,SeekOrigin.Begin);
}

Debug.WriteLine( "Uploading file " + fileName + " to " + remotePath,
"FtpClient" );

while ((bytes = input.Read(buffer,0,buffer.Length)) > 0)
{
cSocket.Send(buffer, bytes, 0);
}

input.Close();

if (cSocket.Connected)
{
cSocket.Close();
}

this.readResponse();

if( this.resultCode != 226 && this.resultCode != 250 ) throw new
FtpException(this.result.Substring(4));
}

// Upload a directory and its file contents

public void UploadDirectory(string path, bool recurse)
{
this.UploadDirectory(path,recurse,"*.*");
}

// Upload a directory and its file contents

public void UploadDirectory(string path, bool recurse, string mask)
{
string[] dirs = path.Replace("/",@"\").Split('\\');
string rootDir = dirs[ dirs.Length - 1 ];

// make the root dir if it doed not exist
if ( this.GetFileList(rootDir).Length < 1 ) this.MakeDir(rootDir);

this.ChangeDir(rootDir);

foreach ( string file in Directory.GetFiles(path,mask) )
{
this.Upload(file,true);
}
if ( recurse )
{
foreach ( string directory in Directory.GetDirectories(path) )
{
this.UploadDirectory(directory,recurse,mask);
}
}

this.ChangeDir("..");
}

// Delete a file from the remote FTP server.

public void DeleteFile(string fileName)
{
if ( !this.loggedin ) this.Login();

this.sendCommand( "DELE " + fileName );

if ( this.resultCode != 250 ) throw new
FtpException(this.result.Substring(4));

Debug.WriteLine( "Deleted file " + fileName, "FtpClient" );
}

// Rename a file on the remote FTP server.

public void RenameFile(string oldFileName,string newFileName, bool
overwrite)
{
if ( !this.loggedin ) this.Login();

this.sendCommand( "RNFR " + oldFileName );

if ( this.resultCode != 350 ) throw new
FtpException(this.result.Substring(4));

if ( !overwrite && this.GetFileList(newFileName).Length > 0 ) throw
new FtpException("File already exists");

this.sendCommand( "RNTO " + newFileName );

if ( this.resultCode != 250 ) throw new
FtpException(this.result.Substring(4));

Debug.WriteLine( "Renamed file " + oldFileName + " to " +
newFileName, "FtpClient" );
}

// Create a directory on the remote FTP server.

public void MakeDir(string dirName)
{
if ( !this.loggedin ) this.Login();

this.sendCommand( "MKD " + dirName );

if ( this.resultCode != 250 && this.resultCode != 257 ) throw new
FtpException(this.result.Substring(4));

Debug.WriteLine( "Created directory " + dirName, "FtpClient" );
}

// Delete a directory on the remote FTP server.

public void RemoveDir(string dirName)
{
if ( !this.loggedin ) this.Login();

this.sendCommand( "RMD " + dirName );

if ( this.resultCode != 250 ) throw new
FtpException(this.result.Substring(4));

Debug.WriteLine( "Removed directory " + dirName, "FtpClient" );
}

// Change the current working directory on the remote FTP server.

public void ChangeDir(string dirName)
{
if( dirName == null || dirName.Equals(".") || dirName.Length == 0 )
{
return;
}

if ( !this.loggedin ) this.Login();

this.sendCommand( "CWD " + dirName );

if ( this.resultCode != 250 ) throw new
FtpException(result.Substring(4));

this.sendCommand( "PWD" );

if ( this.resultCode != 257 ) throw new
FtpException(result.Substring(4));

// gonna have to do better than this....
this.remotePath = this.message.Split('"')[1];

Debug.WriteLine( "Current directory is " + this.remotePath,
"FtpClient" );
}

private void readResponse()
{
this.message = "";
this.result = this.readLine();

if ( this.result.Length > 3 )
this.resultCode = int.Parse( this.result.Substring(0,3) );
else
this.result = null;
}

private string readLine()
{
while(true)
{
this.bytes = clientSocket.Receive( this.buffer, this.buffer.Length,
0 );
this.message += ASCII.GetString( this.buffer, 0, this.bytes );

if ( this.bytes < this.buffer.Length )
{
break;
}
}

string[] msg = this.message.Split('\n');

if ( this.message.Length > 2 )
this.message = msg[ msg.Length - 2 ];

else
this.message = msg[0];
if ( this.message.Length > 4 &&
!this.message.Substring(3,1).Equals(" ") ) return this.readLine();

if ( this.verboseDebugging )
{
for(int i = 0; i < msg.Length - 1; i++)
{
Debug.Write( msg[i], "FtpClient" );
}
}

return message;
}

private void sendCommand(String command)
{
if ( this.verboseDebugging ) Debug.WriteLine(command,"FtpClient");

Byte[] cmdBytes = Encoding.ASCII.GetBytes( ( command + "\r\n"
).ToCharArray() );
clientSocket.Send( cmdBytes, cmdBytes.Length, 0);
this.readResponse();
}

// when doing data transfers, we need to open another socket for
it.

private Socket createDataSocket()
{
this.sendCommand("PASV");

if ( this.resultCode != 227 ) throw new
FtpException(this.result.Substring(4));

int index1 = this.result.IndexOf('(');
int index2 = this.result.IndexOf(')');

string ipData = this.result.Substring(index1+1,index2-index1-1);

int[] parts = new int[6];

int len = ipData.Length;
int partCount = 0;
string buf="";

for (int i = 0; i < len && partCount <= 6; i++)
{
char ch = char.Parse( ipData.Substring(i,1) );

if ( char.IsDigit(ch) )
buf+=ch;

else if (ch != ',')
throw new FtpException("Malformed PASV result: " + result);

if ( ch == ',' || i+1 == len )
{
try
{
parts[partCount++] = int.Parse(buf);
buf = "";
}
catch (Exception ex)
{
throw new FtpException("Malformed PASV result (not supported?): "
+ this.result, ex);
}
}
}

string ipAddress = parts[0] + "."+ parts[1]+ "." + parts[2] + "." +
parts[3];

int port = (parts[4] << 8) + parts[5];

Socket socket = null;
IPEndPoint ep = null;

try
{
socket = new
Socket(AddressFamily.InterNetwork,SocketType.Strea m,ProtocolType.Tcp);
ep = new IPEndPoint(Dns.Resolve(ipAddress).AddressList[0], port);
socket.Connect(ep);
}
catch(Exception ex)
{
// doubtfull....
if ( socket != null && socket.Connected ) socket.Close();

throw new FtpException("Can't connect to remote server", ex);
}

return socket;
}

// Always release those sockets.
private void cleanup()
{
if ( this.clientSocket!=null )
{
this.clientSocket.Close();
this.clientSocket = null;
}
this.loggedin = false;
}

// Destuctor

~FtpConnection()
{
this.cleanup();
}
Here I am calling this class through
FtpConnection ftp = new
FtpConnection("servername","username","password");
ftp.Login();
ftp.Upload(@filename);
But it gives the error Error System.NullReferenceException: Object
reference not set to an instance of an object.

Please help me here.........