VB.NET - Issues with VB.NET FTP Class to UNIX FTP Server

22 Mar 2006 8:57 PM

craig.overton

All,

I am currently developing an FTP class in VB.NET. It's kid tested,
mother approved when trying to access an FTP Server on a Windows box
meaning I can connect, run commands, upload and download a file no
problem. My issues come when I try to use the same class with the same
commands to access an FTP server on a UNIX box. I can connect and login
just fine, but after that all my commands come back "500 'PWD': command
not understood.". Has anyone experienced this error and can help me
solve it. In order to help everyone out the following is my class:

Imports System
Imports System.Net
Imports System.IO
Imports System.Text
Imports System.Text.ASCIIEncoding
Imports System.Net.Sockets
Imports System.Configuration
Imports System.Resources

Public Class FTPClient

#Region "Local Properties"

    '''<summary>
    ''' Public Property: Host - String variable.
    '''</summary>
    Public Property Host() As String
        Get
            Return _Host
        End Get
        Set(ByVal Value As String)
            _Host = Value
        End Set
    End Property

    '''<summary>
    ''' Public Property: Path - String variable.
    '''</summary>
    Public Property Path() As String
        Get
            Return _Path
        End Get
        Set(ByVal Value As String)
            _Path = Value
        End Set
    End Property

    '''<summary>
    ''' Public Property: User - String variable.
    '''</summary>
    Public Property User() As String
        Get
            Return _User
        End Get
        Set(ByVal Value As String)
            _User = Value
        End Set
    End Property

    '''<summary>
    ''' Public Property: Password - String variable.
    '''</summary>
    Public Property Password() As String
        Get
            Return _Password
        End Get
        Set(ByVal Value As String)
            _Password = Value
        End Set
    End Property

    '''<summary>
    ''' Public Property: Port - String variable.
    '''</summary>
    Public Property Port() As String
        Get
            Return _Port
        End Get
        Set(ByVal Value As String)
            _Port = Value
        End Set
    End Property

    '''<summary>
    ''' Public ReadOnly Property: ResponseCode - String variable.
    '''</summary>
    Public ReadOnly Property ResponseCode() As String
        Get
            Return _ResponseCode
        End Get
    End Property

    '''<summary>
    ''' Public ReadOnly Property: ResponseData - String variable.
    '''</summary>
    Public ReadOnly Property ResponseData() As String
        Get
            Return _ResponseData
        End Get
    End Property

#End Region

    ' FTP Default Properties.
    Private _Host As String = "127.0.0.1"
    Private _Path As String = "."
    Private _User As String = "anonymous"
    Private _Password As String = "anonym***@nowhere.com"
    Private _Port As Integer = 21
    Private _ResponseCode As Integer
    Private _ResponseData As String
    Private _FTPCommandSocket As Socket = Nothing
    Private _FTPLogin As Boolean = False

#Region "Public Methods"

    Public Sub New()

    End Sub

    '''<summary>
    ''' Public Function: Login - This function will create a command
and data socket and then send the
    ''' login credentials to the FTP host.
    '''</summary>
    '''<returns>Function returns a Boolean.</returns>
    Public Function Login() As Boolean

        ' Create an FTP command socket.
        CreateCommandSocket()

        ' Send the gathered login information to the FTP host.
        Try
            SendCommand("USER", _User)
            SendCommand("PASS", _Password)
            _FTPLogin = True
        Catch ex As Exception
            ' Login did not work because the FTP login information was
not accepted.
            _ResponseData = "FTP Login function not executed."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP login information was not accepted", ex)
            Return False
        End Try

        ' Login successful.
        Return True

    End Function

    '''<summary>
    ''' Public Sub: Logout - This subroutine will disconnect and close
an FTP command and data socket.
    '''</summary>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub Logout()

        ' Close and destroy the FTP command socket.
        If (_FTPCommandSocket Is Nothing = False) Then
            SendCommand("QUIT", "")
            _FTPCommandSocket.Close()
            _FTPCommandSocket = Nothing
        End If
    End Sub

    '''<summary>
    ''' Public Sub: SendCommand - Provided a Command and Arguements,
this subroutine will execute an FTP Command.
    ''' Commands already taken care of with subroutines below:
    ''' TYPE:   Mode (ASCII or Binary)
    ''' NLST:   List files in directory
    ''' SIZE:   Get file Size
    ''' RETR:   Download a file
    ''' STOR:   Upload a file
    ''' DELE:   Delete a file
    ''' RNFR:   Select a file to be renamed
    ''' RNTO:   Rename a selected file
    ''' PWD:    Get a current directory
    ''' CWD:    Change directory
    ''' RDM:    Remove a directory
    '''</summary>
    '''<param name="FTPCommand">As String</param>
    '''<param name="FTPCommandArguements">As String</param>
    '''<returns>Function returns an FTP stream.</returns>
    Public Sub SendCommand(ByVal FTPCommand As String, ByVal
FTPCommandArguments As String)

        ' Combine FTP command with the FTP command arguements.
        Dim _FTPCommand As String = FTPCommand & " " &
FTPCommandArguments
        _FTPCommand += Environment.NewLine

        ' Convert the FTP command into ASCII text.
        Dim commandBytes() As Byte = ASCII.GetBytes(_FTPCommand)

        Try
            ' Execute the FTP command on the FTP host.
            _FTPCommandSocket.Send(commandBytes, commandBytes.Length,
0)
            ReadResponse()
        Catch ex As Exception
            ' Command was not executed.
            _ResponseData = "FTP SendCommand subroutine not executed."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP command was not accepted", ex)
        End Try
    End Sub

    '''<summary>
    ''' Public Sub: SetBinaryMode - This subroutine sets the FTP mode
to binary.
    '''<param name="mode">As Boolean</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub SetBinaryMode(ByVal mode As Boolean)

        If (mode) Then
            'Send the FTP TYPE command as binary.
            SendCommand("TYPE ", "I")
        Else
            'Send the FTP TYPE command as ASCII.
            SendCommand("TYPE ", "A")
        End If
    End Sub

    '''<summary>
    ''' Public Function: GetDirectoryFileList - This function will get
the names of the files from the provided directory name.
    '''</summary>
    '''<param name="directoryName">As String</param>
    '''<returns>Function returns a string.</returns>
    Public Function GetFileList(ByVal directoryName As String) As
String()

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        ' Create an FTP data socket.
        Dim _FTPDataSocket As Socket = CreateDataSocket()

        'Send an FTP NLST command.
        SendCommand("NLST ", directoryName)

        Const _EndLine As Char = "\n"
        Const _BufferSize As Integer = 512

        Dim _Data As String = ""
        Dim _Buffer(_BufferSize) As Byte
        Dim _BytesRead As Integer = 0

        If _FTPDataSocket.Connected Then
            While (True)
                Array.Clear(_Buffer, 0, _BufferSize)
                _BytesRead = _FTPDataSocket.Receive(_Buffer,
_Buffer.Length, 0)
                _Data += ASCII.GetString(_Buffer, 0, _BytesRead)

                If (_BytesRead < _Buffer.Length) Then Exit While
            End While
        Else
            _ResponseData = "FTP data socket failed to connect."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - GetFileList subroutine failed - FTP data
socket failed to connect.", "")
        End If

        Dim _Parts() As String = _Data.Split(_EndLine)

        ' Close and destroy the FTP data socket.
        If (_FTPDataSocket Is Nothing = False) Then
            _FTPDataSocket.Close()
            _FTPDataSocket = Nothing
        End If

        Return _Parts

    End Function

    '''<summary>
    ''' Public Function: GetFileSize - This function will get the size
of a provided file name.
    '''</summary>
    '''<param name="fileName">As String</param>
    '''<returns>Function returns a Long.</returns>
    ' Get the size of the file on the FTP server.
    Public Function GetFileSize(ByVal fileName As String) As Long

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        Dim _FileSize As Long

        'Send an FTP SIZE command.
        SendCommand("SIZE ", fileName)
        _FileSize = 0

        Return _FileSize = Int64.Parse(_ResponseData.Substring(4))

    End Function

    '''<summary>
    ''' Public Sub: DownloadFile - This subroutine gets a specific
file.
    '''<param name="fileName">As String</param>
    '''<param name="filePath">As String</param>
    '''<optional param name="fileResume">As Boolean</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub DownloadFile(ByVal fileName As String, ByVal filePath As
String, Optional ByVal fileResume As Boolean = False)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        ' Set the FTP mode to binary.
        SetBinaryMode(True)

        ' Create an FTP data socket.
        Dim _FTPDataSocket As Socket = CreateDataSocket()

        ' Create a file.
        Dim _FileStream As Stream
        If (Not (File.Exists(filePath & fileName))) Then
            _FileStream = File.Create(filePath & fileName)
            _FileStream.Close()
        End If

        Dim _FTPFileStreamOutput As FileStream
        _FTPFileStreamOutput = New FileStream(filePath & fileName,
FileMode.Open)

        If fileResume Then
            Dim _FileOffset As Long
            _FileOffset = _FTPFileStreamOutput.Length

            If (_FileOffset > 0) Then
                ' Send an FTP REST command to restart a file.
                SendCommand("REST ", _FileOffset)
                If (_ResponseCode <> 350) Then
                    'The FTP host does not support resuming.
                    _FileOffset = 0
                End If
            End If
            If (_FileOffset <> 0) Then
                _FTPFileStreamOutput.Seek(_FileOffset,
SeekOrigin.Begin)
            End If
        End If

        'Send an FTP RETR command to retrieve a file.
        SendCommand("RETR ", fileName)

        Const _EndLine As Char = "\n"
        Const _BufferSize As Integer = 512

        Dim _Data As String = ""
        Dim _Buffer(_BufferSize) As Byte
        Dim _BytesRead As Integer = 0

        If _FTPDataSocket.Connected Then
            While (True)
                Array.Clear(_Buffer, 0, _BufferSize)
                _BytesRead = _FTPDataSocket.Receive(_Buffer,
_Buffer.Length, 0)
                _FTPFileStreamOutput.Write(_Buffer, 0, _BytesRead)

                If (_BytesRead < _Buffer.Length) Then Exit While
            End While
        Else
            _ResponseData = "FTP data socket failed to connect."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - GetFile subroutine failed - FTP data socket
failed to connect.", "")
        End If

        _FTPFileStreamOutput.Close()

        ' Close and destroy the FTP data socket.
        If (_FTPDataSocket Is Nothing = False) Then
            _FTPDataSocket.Close()
            _FTPDataSocket = Nothing
        End If

    End Sub

    '''<summary>
    ''' Public Sub: UploadFile - This subroutine uploads a specific
file to an FTP host.
    '''<param name="fileName">As String</param>
    '''<param name="filePath">As String</param>
    '''<optional param name="fileResume">As Boolean</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub UploadFile(ByVal fileName As String, ByVal filePath As
String, Optional ByVal fileResume As Boolean = False)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        ' Set the FTP mode to binary.
        SetBinaryMode(True)

        ' Create an FTP data socket.
        Dim _FTPDataSocket As Socket = CreateDataSocket()

        ' Check to see if the file exists locally before the upload.
        If (File.Exists(filePath & fileName)) Then

            ' Open the input stream to read the source file.
            Dim _FTPFileStreamInput As FileStream
            _FTPFileStreamInput = New FileStream(filePath & fileName,
FileMode.Open)

            If fileResume Then
                ' Check to see if part of the file has already been
uploaded.
                Dim _FileOffset As Long
                _FileOffset = 0

                Try
                    _FileOffset = GetFileSize(fileName)
                Catch ex As Exception
                    _FileOffset = 0
                End Try

                If (_FileOffset > 0) Then
                    ' Send an FTP REST command to restart a file.
                    SendCommand("REST ", _FileOffset)
                    If (_ResponseCode <> 350) Then
                        'The FTP host does not support resuming.
                        _FileOffset = 0
                    End If
                End If

                If (_FileOffset <> 0) Then
                    _FTPFileStreamInput.Seek(_FileOffset,
SeekOrigin.Begin)
                End If
            End If

            ' Send an FTP STOR command to store a file.
            SendCommand("STOR ", fileName)

            ' Upload the file.
            Const _BufferSize As Integer = 512
            Dim _Buffer(_BufferSize) As Byte
            Dim _BytesRead As Integer = 0

            _BytesRead = _FTPFileStreamInput.Read(_Buffer, 0,
_Buffer.Length)
            If _FTPDataSocket.Connected Then
                While (_BytesRead > 0)
                    _FTPDataSocket.Send(_Buffer, _BytesRead, 0)
                    _BytesRead = _FTPFileStreamInput.Read(_Buffer, 0,
_Buffer.Length)
                End While

            Else
                    _ResponseData = "FTP data socket failed to
connect."
                    ' Throw New
MPException(AppSettings.Item("Project"), "MP.IT.Web.Library.FTP -
UploadFile subroutine failed - FTP data socket failed to connect.", "")
            End If
            _FTPFileStreamInput.Close()

        Else
            _ResponseData = "File to upload does not exist on local
machine."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - UploadFile subroutine failed - file to upload
does not exist on local machine.", "")
        End If

        ' Close and destroy the FTP data socket.
        If (_FTPDataSocket Is Nothing = False) Then
            _FTPDataSocket.Close()
            _FTPDataSocket = Nothing
        End If

    End Sub

    '''<summary>
    ''' Public Sub: UploadFile - This subroutine deletes a specific
file on an FTP host.
    '''<param name="fileName">As String</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub DeleteFile(ByVal fileName As String)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        ' Send an FTP DELE command to delete a file.
        SendCommand("DELE ", fileName)

    End Sub

    '''<summary>
    ''' Public Sub: RenameFile - This subroutine renames a specific
file on an FTP host.
    '''<param name="fileName">As String</param>
    '''<param name="fileNewName">As String</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub RenameFile(ByVal fileName As String, ByVal fileNewName
As String)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        ' Send an FTP RNFR command to select a file to be renamed.
        SendCommand("RNFR ", fileName)

        'Send an FTP RNTO command to rename the selected file to a new
file name.
        SendCommand("RNTO ", fileNewName)

    End Sub

    '''<summary>
    ''' Public Sub: GetDirectory - This subroutine gets the current
directory on an FTP host.
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub GetDirectory()

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        'Send an FTP CWD command to change to a directory.
        SendCommand("PWD ", "")

    End Sub

    '''<summary>
    ''' Public Sub: ChangeDirectory - This subroutine changes to a
directory on an FTP host.
    '''<param name="directoryName">As String</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub ChangeDirectory(ByVal directoryName As String)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        'Check if in the root directory.
        If (directoryName.Equals(".")) Then
            Exit Sub
        End If

        'Send an FTP CWD command to change to a directory.
        SendCommand("CWD ", directoryName)

    End Sub

    '''<summary>
    ''' Public Sub: CreateDirectory - This subroutine creates a new
directory on an FTP host.
    '''<param name="directoryName">As String</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub CreateDirectory(ByVal directoryName As String)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        'Send an FTP MKD command to make a new directory.
        SendCommand("MKD ", directoryName)

    End Sub

    '''<summary>
    ''' Public Sub: RemoveDirectory - This subroutine removes a
directory on an FTP host.
    '''<param name="directoryName">As String</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub RemoveDirectory(ByVal directoryName As String)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        'Send an FTP RMD command to remove a directory.
        SendCommand("RMD ", directoryName)

    End Sub

#End Region

#Region "Private Methods"

    '''<summary>
    ''' Private Sub: CreateCommandSocket - Provided a Host and a port
this subroutine will instantiate an FTP command socket.
    '''</summary>
    '''<returns>Subroutine returns nothing.</returns>
    Private Sub CreateCommandSocket()

        ' Create the FTP command socket.
        _FTPCommandSocket = New Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp)

        Try
            Dim HostMachine As IPEndPoint = New
IPEndPoint(Dns.Resolve(_Host).AddressList(0), _Port)
            Try
                ' Connect the FTP command socket to the FTP host
machine.
                _FTPCommandSocket.Connect(HostMachine)
            Catch ex As Exception
                ' Connection could not be opened due to malformed
connection.
                _ResponseData = "FTP Command Socket Connection Could
Not Be Established."
                ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP Command Socket Connection Could Not Be
Established.", ex)
            End Try
        Catch ex As Exception
            ' Connection could not be opened because DNS cannot resolve
the host IP.
            _ResponseData = "FTP Command Socket Connection Could Not Be
Established. Connection could not be opened because DNS cannot resolve
the host IP."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP Command Socket Connection Could Not Be
Established. DNS cannot resolve the FTP host.", ex)
        End Try
        _ResponseData = "FTP Command Socket Connection Established."
        ReadResponse()

    End Sub

    '''<summary>
    ''' Private Function: CreateDataSocket - Provided that a PASV
command has been sent to the host, this function returns
    ''' an FTP data socket.
    '''</summary>
    '''<returns>Subroutine returns nothing.</returns>
    Private Function CreateDataSocket() As Socket

        Dim _FTPDataSocket As Socket
        Dim _FTPHostIPFrontBracket As Integer
        Dim _FTPHostIPBackBracket As Integer
        Dim _FTPHostIPData As String
        Dim _FTPHostIPLength As Integer
        Dim _FTPHostIPPartCount As Integer
        Dim _FTPHostIPParts(6) As Integer
        Dim _FTPHostIPCharater As Char
        Dim _Buffer As String
        Dim _Counter As Integer

        'Send an FTP PASV command to use passive data connection.
        SendCommand("PASV", "")

        _FTPHostIPFrontBracket = _ResponseData.IndexOf("(")
        _FTPHostIPBackBracket = _ResponseData.IndexOf(")")
        _FTPHostIPData = _ResponseData.Substring(_FTPHostIPFrontBracket
+ 1, _FTPHostIPBackBracket - _FTPHostIPFrontBracket - 1)

        _FTPHostIPLength = _FTPHostIPData.Length
        _FTPHostIPPartCount = 0
        _Buffer = ""

        For _Counter = 0 To ((_FTPHostIPLength - 1) And
_FTPHostIPPartCount <= 6)
            _FTPHostIPCharater =
Char.Parse(_FTPHostIPData.Substring(_Counter, 1))
            If (Char.IsDigit(_FTPHostIPCharater)) Then
                _Buffer += _FTPHostIPCharater
            ElseIf (_FTPHostIPCharater <> ",") Then
                ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP Host did not accept the PASV command.",
"")
            End If

            If ((_FTPHostIPCharater = ",") Or (_Counter + 1 =
_FTPHostIPLength)) Then
                Try
                    _FTPHostIPParts(_FTPHostIPPartCount) =
Int32.Parse(_Buffer)
                    _FTPHostIPPartCount += 1
                    _Buffer = ""
                Catch ex As Exception
                    ' Throw New
MPException(AppSettings.Item("Project"), "MP.IT.Web.Library.FTP - FTP
Host did not accept the PASV command.", ex)
                End Try
            End If
        Next

        ' Create the data host.
        Dim _DataHost As String = _FTPHostIPParts(0) & "." &
_FTPHostIPParts(1) & "." & _FTPHostIPParts(2) & "." &
_FTPHostIPParts(3)

        ' Create the data port.
        Dim _DataPort As Integer = _FTPHostIPParts(4) << 8

        ' Determine the data port number.
        _DataPort = _DataPort + _FTPHostIPParts(5)

        ' Create the FTP data socket from the data host and data port.
        _FTPDataSocket = New Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp)

        Try
            Dim HostMachine As IPEndPoint = New
IPEndPoint(Dns.Resolve(_DataHost).AddressList(0), _DataPort)
            Try
                ' Connect the FTP data socket to the FTP host machine.
                _FTPDataSocket.Connect(HostMachine)
                Return _FTPDataSocket
            Catch ex As Exception
                ' Connection could not be opened due to malformed
connection.
                _ResponseData = "FTP Data Socket Connection Could Not
Be Established."
                ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP Data Socket Connection Could Not Be
Established.", ex)
            End Try
        Catch ex As Exception
            ' Connection could not be opened because DNS cannot resolve
the host IP.
            _ResponseData = "FTP Data Socket Connection Could Not Be
Established. Connection could not be opened because DNS cannot resolve
the host IP."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP Data Socket Connection Could Not Be
Established. DNS cannot resolve the FTP host.", ex)
        End Try
        _ResponseData = "FTP Data Socket Connection Established."

    End Function

    '''<summary>
    ''' Private Sub: ReadResponse - This subroutine will read line by
line the reply to
    ''' a command sent to an FTP host.
    '''</summary>
    '''<returns>Function returns a string.</returns>
    Private Sub ReadResponse()

        ' Read the response from the FTP host.
        _ResponseData = ReadLine(False)
        _ResponseCode = Int32.Parse(_ResponseData.Substring(0, 3))

    End Sub

    '''<summary>
    ''' Private Function: ReadLine - This function handles the actual
reading of the FTP host reply.
    '''</summary>
    '''<param name="clearResponse">As Boolean</param>
    '''<returns>Function returns a string.</returns>
    Private Function ReadLine(ByVal clearResponse As Boolean) As String

        Const _EndLine As Char = "\n"
        Const _BufferSize As Integer = 512

        Dim _Data As String = ""
        Dim _Buffer(_BufferSize) As Byte
        Dim _BytesRead As Integer = 0

        If (clearResponse = True) Then _ResponseData = String.Empty

        While (True)
            Array.Clear(_Buffer, 0, _BufferSize)
            _BytesRead = _FTPCommandSocket.Receive(_Buffer,
_Buffer.Length, 0)
            _Data += ASCII.GetString(_Buffer, 0, _BytesRead)

            If (_BytesRead < _Buffer.Length) Then Exit While
        End While

        Dim _Parts() As String = _Data.Split(_EndLine)

        If (_Parts.Length > 2) Then
            _ResponseData = _Parts(_Parts.Length - 2)
        Else
            _ResponseData = _Parts(0)
        End If

        If (_ResponseData.Substring(3, 1).Equals(" ") = False) Then
            Return ReadLine(False)
        End If

        Return _ResponseData
    End Function

#End Region

End Class

22 Mar 2006 10:26 PM

Tom Shelton

craig.over***@gmail.com wrote:

> All,
>
> I am currently developing an FTP class in VB.NET. It's kid tested,
> mother approved when trying to access an FTP Server on a Windows box
> meaning I can connect, run commands, upload and download a file no
> problem. My issues come when I try to use the same class with the same
> commands to access an FTP server on a UNIX box. I can connect and login
> just fine, but after that all my commands come back "500 'PWD': command
> not understood.". Has anyone experienced this error and can help me
> solve it. In order to help everyone out the following is my class:

<snip>

Craig...

Is there a reason you are implementing this code when there are free
and working ftp clients available for .NET (Indy project comes to
mind)? If this is for personal learning I will be glad to look over
this code, but it might take a little debugging time :)

--
Tom Shelton [MVP]

22 Mar 2006 10:34 PM

craig.overton

Tom,

You hit the nail on the head, I am learning, but I just can't seem to
understand how it works so well with a Windows environment FTP server
and then won't get passed the password command in the UNIX environment
FTP. Take as much time as you want. I am interested to know and the
code should be cut and paste for you.

Craig

22 Mar 2006 10:41 PM

Tom Shelton

craig.over***@gmail.com wrote:

> Tom,
>
> You hit the nail on the head, I am learning, but I just can't seem to
> understand how it works so well with a Windows environment FTP server
> and then won't get passed the password command in the UNIX environment
> FTP. Take as much time as you want. I am interested to know and the
> code should be cut and paste for you.
>
> Craig

Well... Actually, it's a bit hard to cut and past through Google.
But, I've almost got it to compile :)

My first response - since I haven't got it to compile just yet is, you
obviously didn't have Option Strict turned on. I would suggest that
you make this a habbit for most code. Anyway, I'll get back to you
once I've got a clean compile.

--
Tom Shelton [MVP]

22 Mar 2006 11:06 PM

craig.overton

Tom,

Don't bother. I found my mistake and I am pretty much an idiot for it.
Basically I have my subroutine for sending commands called SendCommand.
In that sub I take care of adding the space character after the command
before the command arguements. Well I really should have cleaned up
that sub to make it more efficient. Basically not all FTP commands have
arguements so I really shouldn't being adding that space unless there
are arguements. To make matters even more fun, in all my subroutines
thereafter I added a space after the FTP command and then shipped it to
the SendCommand sub which was already messed up, thus actually doubling
the space character between the FTP command and the FTP command
arguements if there were arguements. Somehow Windows based FTP servers
let this fly whereas Unix FTP servers cannot even understand what was
sent to it as a command. The fixed code that is working across the
board is below. There isn't much it doesn't do. I should probably add
events and a lot more error checking, but it will do for now: Tom thank
you for at least taking some time to look at it.

Craig

Imports System
Imports System.Net
Imports System.IO
Imports System.Text
Imports System.Text.ASCIIEncoding
Imports System.Net.Sockets
Imports System.Configuration
Imports System.Resources

Public Class FTPClient

#Region "Local Properties"

    '''<summary>
    ''' Public Property: Host - String variable.
    '''</summary>
    Public Property Host() As String
        Get
            Return _Host
        End Get
        Set(ByVal Value As String)
            _Host = Value
        End Set
    End Property

    '''<summary>
    ''' Public Property: Path - String variable.
    '''</summary>
    Public Property Path() As String
        Get
            Return _Path
        End Get
        Set(ByVal Value As String)
            _Path = Value
        End Set
    End Property

    '''<summary>
    ''' Public Property: User - String variable.
    '''</summary>
    Public Property User() As String
        Get
            Return _User
        End Get
        Set(ByVal Value As String)
            _User = Value
        End Set
    End Property

    '''<summary>
    ''' Public Property: Password - String variable.
    '''</summary>
    Public Property Password() As String
        Get
            Return _Password
        End Get
        Set(ByVal Value As String)
            _Password = Value
        End Set
    End Property

    '''<summary>
    ''' Public Property: Port - String variable.
    '''</summary>
    Public Property Port() As String
        Get
            Return _Port
        End Get
        Set(ByVal Value As String)
            _Port = Value
        End Set
    End Property

    '''<summary>
    ''' Public ReadOnly Property: ResponseCode - String variable.
    '''</summary>
    Public ReadOnly Property ResponseCode() As String
        Get
            Return _ResponseCode
        End Get
    End Property

    '''<summary>
    ''' Public ReadOnly Property: ResponseData - String variable.
    '''</summary>
    Public ReadOnly Property ResponseData() As String
        Get
            Return _ResponseData
        End Get
    End Property

#End Region

    ' FTP Default Properties.
    Private _Host As String = "127.0.0.1"
    Private _Path As String = "."
    Private _User As String = "anonymous"
    Private _Password As String = "anonym***@nowhere.com"
    Private _Port As Integer = 21
    Private _ResponseCode As Integer
    Private _ResponseData As String
    Private _FTPCommandSocket As Socket = Nothing
    Private _FTPLogin As Boolean = False
    Private _FTPCommandSocketInstalled As Boolean = False

#Region "Public Methods"

    Public Sub New()

    End Sub

    '''<summary>
    ''' Public Function: Login - This function will create a command
and data socket and then send the
    ''' login credentials to the FTP host.
    '''</summary>
    '''<returns>Function returns a Boolean.</returns>
    Public Function Login() As Boolean

        ' Create an FTP command socket.
        CreateCommandSocket()

        ' Send the gathered login information to the FTP host.
        Try
            SendCommand("USER", _User)
            SendCommand("PASS", _Password)
            _FTPLogin = True
        Catch ex As Exception
            ' Login did not work because the FTP login information was
not accepted.
            _ResponseData = "FTP Login function not executed."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP login information was not accepted", ex)
            Return False
        End Try

        ' Login successful.
        Return True

    End Function

    '''<summary>
    ''' Public Sub: Logout - This subroutine will disconnect and close
an FTP command and data socket.
    '''</summary>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub Logout()

        ' Close and destroy the FTP command socket.
        If (_FTPCommandSocket Is Nothing = False) Then
            SendCommand("QUIT", "")
            _FTPCommandSocket.Close()
            _FTPCommandSocket = Nothing
        End If
    End Sub

    '''<summary>
    ''' Public Sub: SendCommand - Provided a Command and Arguements,
this subroutine will execute an FTP Command.
    ''' Commands already taken care of with subroutines below:
    ''' TYPE:   Mode (ASCII or Binary)
    ''' NLST:   List files in directory
    ''' SIZE:   Get file Size
    ''' RETR:   Download a file
    ''' STOR:   Upload a file
    ''' DELE:   Delete a file
    ''' RNFR:   Select a file to be renamed
    ''' RNTO:   Rename a selected file
    ''' PWD:    Get a current directory
    ''' CWD:    Change directory
    ''' RDM:    Remove a directory
    '''</summary>
    '''<param name="FTPCommand">As String</param>
    '''<param name="FTPCommandArguements">As String</param>
    '''<returns>Function returns an FTP stream.</returns>
    Public Sub SendCommand(ByVal FTPCommand As String, ByVal
FTPCommandArguments As String)

        Dim _FTPCommand As String
        ' Combine FTP command with the FTP command arguements.
        If FTPCommandArguments = String.Empty Then
            _FTPCommand = FTPCommand
        Else
            _FTPCommand = FTPCommand & " " & FTPCommandArguments
        End If
        _FTPCommand += Environment.NewLine

        ' Convert the FTP command into ASCII text.
        Dim commandBytes() As Byte = ASCII.GetBytes(_FTPCommand)

        Try
            ' Execute the FTP command on the FTP host.
            _FTPCommandSocket.Send(commandBytes, commandBytes.Length,
0)
            ReadResponse()
        Catch ex As Exception
            ' Command was not executed.
            _ResponseData = "FTP SendCommand subroutine not executed."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP command was not accepted", ex)
        End Try
    End Sub

    '''<summary>
    ''' Public Sub: SetBinaryMode - This subroutine sets the FTP mode
to binary.
    '''<param name="mode">As Boolean</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub SetBinaryMode(ByVal mode As Boolean)

        If (mode) Then
            'Send the FTP TYPE command as binary.
            SendCommand("TYPE", "I")
        Else
            'Send the FTP TYPE command as ASCII.
            SendCommand("TYPE", "A")
        End If
    End Sub

    '''<summary>
    ''' Public Function: GetDirectoryFileList - This function will get
the names of the files from the provided directory name.
    '''</summary>
    '''<param name="directoryName">As String</param>
    '''<returns>Function returns a string.</returns>
    Public Function GetFileList(ByVal directoryName As String) As
String()

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        ' Create an FTP data socket.
        Dim _FTPDataSocket As Socket = CreateDataSocket()

        'Send an FTP NLST command.
        SendCommand("NLST", directoryName)

        Const _EndLine As Char = "\n"
        Const _BufferSize As Integer = 512

        Dim _Data As String = ""
        Dim _Buffer(_BufferSize) As Byte
        Dim _BytesRead As Integer = 0

        If _FTPDataSocket.Connected Then
            While (True)
                Array.Clear(_Buffer, 0, _BufferSize)
                _BytesRead = _FTPDataSocket.Receive(_Buffer,
_Buffer.Length, 0)
                _Data += ASCII.GetString(_Buffer, 0, _BytesRead)

                If (_BytesRead < _Buffer.Length) Then Exit While
            End While
        Else
            _ResponseData = "FTP data socket failed to connect."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - GetFileList subroutine failed - FTP data
socket failed to connect.", "")
        End If

        Dim _Parts() As String = _Data.Split(_EndLine)

        ' Close and destroy the FTP data socket.
        If (_FTPDataSocket Is Nothing = False) Then
            _FTPDataSocket.Close()
            _FTPDataSocket = Nothing
        End If

        Return _Parts

    End Function

    '''<summary>
    ''' Public Function: GetFileSize - This function will get the size
of a provided file name.
    '''</summary>
    '''<param name="fileName">As String</param>
    '''<returns>Function returns a Long.</returns>
    ' Get the size of the file on the FTP server.
    Public Function GetFileSize(ByVal fileName As String) As Long

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        Dim _FileSize As Long

        'Send an FTP SIZE command.
        SendCommand("SIZE", fileName)
        _FileSize = 0

        Return _FileSize = Int64.Parse(_ResponseData.Substring(4))

    End Function

    '''<summary>
    ''' Public Sub: DownloadFile - This subroutine gets a specific
file.
    '''<param name="fileName">As String</param>
    '''<param name="filePath">As String</param>
    '''<optional param name="fileResume">As Boolean</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub DownloadFile(ByVal fileName As String, ByVal filePath As
String, Optional ByVal fileResume As Boolean = False)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        ' Set the FTP mode to binary.
        SetBinaryMode(True)

        ' Create an FTP data socket.
        Dim _FTPDataSocket As Socket = CreateDataSocket()

        ' Create a file.
        Dim _FileStream As Stream
        If (Not (File.Exists(filePath & fileName))) Then
            _FileStream = File.Create(filePath & fileName)
            _FileStream.Close()
        End If

        Dim _FTPFileStreamOutput As FileStream
        _FTPFileStreamOutput = New FileStream(filePath & fileName,
FileMode.Open)

        If fileResume Then
            Dim _FileOffset As Long
            _FileOffset = _FTPFileStreamOutput.Length

            If (_FileOffset > 0) Then
                ' Send an FTP REST command to restart a file.
                SendCommand("REST", _FileOffset)
                If (_ResponseCode <> 350) Then
                    'The FTP host does not support resuming.
                    _FileOffset = 0
                End If
            End If
            If (_FileOffset <> 0) Then
                _FTPFileStreamOutput.Seek(_FileOffset,
SeekOrigin.Begin)
            End If
        End If

        'Send an FTP RETR command to retrieve a file.
        SendCommand("RETR", fileName)

        Const _EndLine As Char = "\n"
        Const _BufferSize As Integer = 512

        Dim _Data As String = ""
        Dim _Buffer(_BufferSize) As Byte
        Dim _BytesRead As Integer = 0

        If _FTPDataSocket.Connected Then
            While (True)
                Array.Clear(_Buffer, 0, _BufferSize)
                _BytesRead = _FTPDataSocket.Receive(_Buffer,
_Buffer.Length, 0)
                _FTPFileStreamOutput.Write(_Buffer, 0, _BytesRead)

                If (_BytesRead < _Buffer.Length) Then Exit While
            End While
        Else
            _ResponseData = "FTP data socket failed to connect."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - GetFile subroutine failed - FTP data socket
failed to connect.", "")
        End If

        _FTPFileStreamOutput.Close()

        ' Close and destroy the FTP data socket.
        If (_FTPDataSocket Is Nothing = False) Then
            _FTPDataSocket.Close()
            _FTPDataSocket = Nothing
        End If

    End Sub

    '''<summary>
    ''' Public Sub: UploadFile - This subroutine uploads a specific
file to an FTP host.
    '''<param name="fileName">As String</param>
    '''<param name="filePath">As String</param>
    '''<optional param name="fileResume">As Boolean</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub UploadFile(ByVal fileName As String, ByVal filePath As
String, Optional ByVal fileResume As Boolean = False)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        ' Set the FTP mode to binary.
        SetBinaryMode(True)

        ' Create an FTP data socket.
        Dim _FTPDataSocket As Socket = CreateDataSocket()

        ' Check to see if the file exists locally before the upload.
        If (File.Exists(filePath & fileName)) Then

            ' Open the input stream to read the source file.
            Dim _FTPFileStreamInput As FileStream
            _FTPFileStreamInput = New FileStream(filePath & fileName,
FileMode.Open)

            If fileResume Then
                ' Check to see if part of the file has already been
uploaded.
                Dim _FileOffset As Long
                _FileOffset = 0

                Try
                    _FileOffset = GetFileSize(fileName)
                Catch ex As Exception
                    _FileOffset = 0
                End Try

                If (_FileOffset > 0) Then
                    ' Send an FTP REST command to restart a file.
                    SendCommand("REST", _FileOffset)
                    If (_ResponseCode <> 350) Then
                        'The FTP host does not support resuming.
                        _FileOffset = 0
                    End If
                End If

                If (_FileOffset <> 0) Then
                    _FTPFileStreamInput.Seek(_FileOffset,
SeekOrigin.Begin)
                End If
            End If

            ' Send an FTP STOR command to store a file.
            SendCommand("STOR", fileName)

            ' Upload the file.
            Const _BufferSize As Integer = 512
            Dim _Buffer(_BufferSize) As Byte
            Dim _BytesRead As Integer = 0

            _BytesRead = _FTPFileStreamInput.Read(_Buffer, 0,
_Buffer.Length)
            If _FTPDataSocket.Connected Then
                While (_BytesRead > 0)
                    _FTPDataSocket.Send(_Buffer, _BytesRead, 0)
                    _BytesRead = _FTPFileStreamInput.Read(_Buffer, 0,
_Buffer.Length)
                End While

            Else
                    _ResponseData = "FTP data socket failed to
connect."
                    ' Throw New
MPException(AppSettings.Item("Project"), "MP.IT.Web.Library.FTP -
UploadFile subroutine failed - FTP data socket failed to connect.", "")
            End If
            _FTPFileStreamInput.Close()

        Else
            _ResponseData = "File to upload does not exist on local
machine."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - UploadFile subroutine failed - file to upload
does not exist on local machine.", "")
        End If

        ' Close and destroy the FTP data socket.
        If (_FTPDataSocket Is Nothing = False) Then
            _FTPDataSocket.Close()
            _FTPDataSocket = Nothing
        End If

    End Sub

    '''<summary>
    ''' Public Sub: UploadFile - This subroutine deletes a specific
file on an FTP host.
    '''<param name="fileName">As String</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub DeleteFile(ByVal fileName As String)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        ' Send an FTP DELE command to delete a file.
        SendCommand("DELE", fileName)

    End Sub

    '''<summary>
    ''' Public Sub: RenameFile - This subroutine renames a specific
file on an FTP host.
    '''<param name="fileName">As String</param>
    '''<param name="fileNewName">As String</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub RenameFile(ByVal fileName As String, ByVal fileNewName
As String)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        ' Send an FTP RNFR command to select a file to be renamed.
        SendCommand("RNFR", fileName)

        'Send an FTP RNTO command to rename the selected file to a new
file name.
        SendCommand("RNTO", fileNewName)

    End Sub

    '''<summary>
    ''' Public Sub: GetDirectory - This subroutine gets the current
directory on an FTP host.
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub GetDirectory()

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        'Send an FTP CWD command to change to a directory.
        SendCommand("PWD", "")

    End Sub

    '''<summary>
    ''' Public Sub: ChangeDirectory - This subroutine changes to a
directory on an FTP host.
    '''<param name="directoryName">As String</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub ChangeDirectory(ByVal directoryName As String)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        'Check if in the root directory.
        If (directoryName.Equals(".")) Then
            Exit Sub
        End If

        'Send an FTP CWD command to change to a directory.
        SendCommand("CWD", directoryName)

    End Sub

    '''<summary>
    ''' Public Sub: CreateDirectory - This subroutine creates a new
directory on an FTP host.
    '''<param name="directoryName">As String</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub CreateDirectory(ByVal directoryName As String)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        'Send an FTP MKD command to make a new directory.
        SendCommand("MKD", directoryName)

    End Sub

    '''<summary>
    ''' Public Sub: RemoveDirectory - This subroutine removes a
directory on an FTP host.
    '''<param name="directoryName">As String</param>
    '''<returns>Subroutine returns nothing.</returns>
    Public Sub RemoveDirectory(ByVal directoryName As String)

        ' Check to see if user is logged into FTP host.
        If Not _FTPLogin Then
            Login()
        End If

        'Send an FTP RMD command to remove a directory.
        SendCommand("RMD", directoryName)

    End Sub

#End Region

#Region "Private Methods"

    '''<summary>
    ''' Private Sub: CreateCommandSocket - Provided a Host and a port
this subroutine will instantiate an FTP command socket.
    '''</summary>
    '''<returns>Subroutine returns nothing.</returns>
    Private Sub CreateCommandSocket()

        ' Create the FTP command socket.
        _FTPCommandSocket = New Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp)

        Try
            Dim HostMachine As IPEndPoint = New
IPEndPoint(Dns.Resolve(_Host).AddressList(0), _Port)
            Try
                ' Connect the FTP command socket to the FTP host
machine.
                _FTPCommandSocket.Connect(HostMachine)
            Catch ex As Exception
                ' Connection could not be opened due to malformed
connection.
                _ResponseData = "FTP Command Socket Connection Could
Not Be Established."
                ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP Command Socket Connection Could Not Be
Established.", ex)
            End Try
        Catch ex As Exception
            ' Connection could not be opened because DNS cannot resolve
the host IP.
            _ResponseData = "FTP Command Socket Connection Could Not Be
Established. Connection could not be opened because DNS cannot resolve
the host IP."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP Command Socket Connection Could Not Be
Established. DNS cannot resolve the FTP host.", ex)
        End Try
        _ResponseData = "FTP Command Socket Connection Established."
        ReadResponse()

    End Sub

    '''<summary>
    ''' Private Function: CreateDataSocket - Provided that a PASV
command has been sent to the host, this function returns
    ''' an FTP data socket.
    '''</summary>
    '''<returns>Subroutine returns nothing.</returns>
    Private Function CreateDataSocket() As Socket

        Dim _FTPDataSocket As Socket
        Dim _FTPHostIPFrontBracket As Integer
        Dim _FTPHostIPBackBracket As Integer
        Dim _FTPHostIPData As String
        Dim _FTPHostIPLength As Integer
        Dim _FTPHostIPPartCount As Integer
        Dim _FTPHostIPParts(6) As Integer
        Dim _FTPHostIPCharater As Char
        Dim _Buffer As String
        Dim _Counter As Integer

        'Send an FTP PASV command to use passive data connection.
        SendCommand("PASV", "")

        _FTPHostIPFrontBracket = _ResponseData.IndexOf("(")
        _FTPHostIPBackBracket = _ResponseData.IndexOf(")")
        _FTPHostIPData = _ResponseData.Substring(_FTPHostIPFrontBracket
+ 1, _FTPHostIPBackBracket - _FTPHostIPFrontBracket - 1)

        _FTPHostIPLength = _FTPHostIPData.Length
        _FTPHostIPPartCount = 0
        _Buffer = ""

        For _Counter = 0 To ((_FTPHostIPLength - 1) And
_FTPHostIPPartCount <= 6)
            _FTPHostIPCharater =
Char.Parse(_FTPHostIPData.Substring(_Counter, 1))
            If (Char.IsDigit(_FTPHostIPCharater)) Then
                _Buffer += _FTPHostIPCharater
            ElseIf (_FTPHostIPCharater <> ",") Then
                ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP Host did not accept the PASV command.",
"")
            End If

            If ((_FTPHostIPCharater = ",") Or (_Counter + 1 =
_FTPHostIPLength)) Then
                Try
                    _FTPHostIPParts(_FTPHostIPPartCount) =
Int32.Parse(_Buffer)
                    _FTPHostIPPartCount += 1
                    _Buffer = ""
                Catch ex As Exception
                    ' Throw New
MPException(AppSettings.Item("Project"), "MP.IT.Web.Library.FTP - FTP
Host did not accept the PASV command.", ex)
                End Try
            End If
        Next

        ' Create the data host.
        Dim _DataHost As String = _FTPHostIPParts(0) & "." &
_FTPHostIPParts(1) & "." & _FTPHostIPParts(2) & "." &
_FTPHostIPParts(3)

        ' Create the data port.
        Dim _DataPort As Integer = _FTPHostIPParts(4) << 8

        ' Determine the data port number.
        _DataPort = _DataPort + _FTPHostIPParts(5)

        ' Create the FTP data socket from the data host and data port.
        _FTPDataSocket = New Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp)

        Try
            Dim HostMachine As IPEndPoint = New
IPEndPoint(Dns.Resolve(_DataHost).AddressList(0), _DataPort)
            Try
                ' Connect the FTP data socket to the FTP host machine.
                _FTPDataSocket.Connect(HostMachine)
                Return _FTPDataSocket
            Catch ex As Exception
                ' Connection could not be opened due to malformed
connection.
                _ResponseData = "FTP Data Socket Connection Could Not
Be Established."
                ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP Data Socket Connection Could Not Be
Established.", ex)
            End Try
        Catch ex As Exception
            ' Connection could not be opened because DNS cannot resolve
the host IP.
            _ResponseData = "FTP Data Socket Connection Could Not Be
Established. Connection could not be opened because DNS cannot resolve
the host IP."
            ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP Data Socket Connection Could Not Be
Established. DNS cannot resolve the FTP host.", ex)
        End Try
        _ResponseData = "FTP Data Socket Connection Established."

    End Function

    '''<summary>
    ''' Private Sub: ReadResponse - This subroutine will read line by
line the reply to
    ''' a command sent to an FTP host.
    '''</summary>
    '''<returns>Function returns a string.</returns>
    Private Sub ReadResponse()

        ' Read the response from the FTP host.
        _ResponseData = ReadLine(False)
        _ResponseCode = Int32.Parse(_ResponseData.Substring(0, 3))

    End Sub

    '''<summary>
    ''' Private Function: ReadLine - This function handles the actual
reading of the FTP host reply.
    '''</summary>
    '''<param name="clearResponse">As Boolean</param>
    '''<returns>Function returns a string.</returns>
    Private Function ReadLine(ByVal clearResponse As Boolean) As String

        Const _EndLine As Char = "\n"
        Const _BufferSize As Integer = 512

        Dim _Data As String = ""
        Dim _Buffer(_BufferSize) As Byte
        Dim _BytesRead As Integer = 0

        If (clearResponse = True) Then _ResponseData = String.Empty

        While (True)
            Array.Clear(_Buffer, 0, _BufferSize)
            _BytesRead = _FTPCommandSocket.Receive(_Buffer,
_Buffer.Length, 0)
            _Data += ASCII.GetString(_Buffer, 0, _BytesRead)

            If (_BytesRead < _Buffer.Length) Then Exit While
        End While

        Dim _Parts() As String = _Data.Split(_EndLine)

        If (_Parts.Length > 2) Then
            _ResponseData = _Parts(_Parts.Length - 2)
        Else
            _ResponseData = _Parts(0)
        End If

        If (_ResponseData.Substring(3, 1).Equals(" ") = False) Then
            Return ReadLine(False)
        End If

        Return _ResponseData
    End Function

#End Region

End Class

22 Mar 2006 10:57 PM

craig.overton

Tom,

You hit the nail on the head, I am learning, but I just can't seem to
understand how it works so well with a Windows environment FTP server
and then won't get passed the password command in the UNIX environment
FTP. Take as much time as you want. I am interested to know and the
code should be cut and paste for you.

Craig

23 Mar 2006 8:32 AM

Cor Ligthert [MVP]

Tom,

> Is there a reason you are implementing this code when there are free
> and working ftp clients available for .NET (Indy project comes to
> mind)? If this is for personal learning I will be glad to look over
> this code, but it might take a little debugging time :)
>

At least it is a standard dotNet part now, so there is in my opinion nothing
wrong with learning that.

http://msdn2.microsoft.com/en-us/library/ms144318(VS.80).aspx

Just my thought,

Cor

22 Mar 2006 11:07 PM

Tom Shelton

craig.over***@gmail.com wrote:

> All,
>
> I am currently developing an FTP class in VB.NET. It's kid tested,
> mother approved when trying to access an FTP Server on a Windows box
> meaning I can connect, run commands, upload and download a file no
> problem. My issues come when I try to use the same class with the same
> commands to access an FTP server on a UNIX box. I can connect and login
> just fine, but after that all my commands come back "500 'PWD': command
> not understood.". Has anyone experienced this error and can help me
> solve it. In order to help everyone out the following is my class:

Ok... I won't repost all of the code, but here is the basic problem.
You have extra spaces in the command strings. This happens because you
are passing data like this:

        Public Sub GetDirectory()

            ' Check to see if user is logged into FTP host.
            If Not _FTPLogin Then
                Login()
            End If

            'Send an FTP CWD command to change to a directory.
            SendCommand("PWD ", "")

        End Sub

This should really be:

        Public Sub GetDirectory()

            ' Check to see if user is logged into FTP host.
            If Not _FTPLogin Then
                Login()
            End If

            'Send an FTP CWD command to change to a directory.
            SendCommand("PWD", "")

        End Sub

Of course - this doesn't completely fix your problem. I modified your
SendCommand a little bit as well:

        Public Sub SendCommand(ByVal FTPCommand As String, ByVal
FTPCommandArguments As String)

            ' Combine FTP command with the FTP command arguements.
            Dim _FTPCommand As String = IIf(FTPCommandArguments.Length

> 0, FTPCommand & " " & FTPCommandArguments, FTPCommand)

            _FTPCommand += Environment.NewLine

            ' Convert the FTP command into ASCII text.
            Dim commandBytes() As Byte = ASCII.GetBytes(_FTPCommand)

            Try
                ' Execute the FTP command on the FTP host.
                _FTPCommandSocket.Send(commandBytes,
commandBytes.Length, 0)
                ReadResponse()
            Catch ex As Exception
                ' Command was not executed.
                _ResponseData = "FTP SendCommand subroutine not
executed."
                ' Throw New MPException(AppSettings.Item("Project"),
"MP.IT.Web.Library.FTP - FTP command was not accepted", ex)
            End Try
        End Sub

I can make a lot more suggestions about how to code this - but this
should fix your immediate issue (go through and fix all the methods to
not pass the command + space, but just the command). Apparently, UNIX
ftp servers - and I could recreate this going to our SCO server - are
picky about the extra spaces, and windows ftp server is not.

--
Tom Shelton [MVP]

23 Mar 2006 8:30 AM

Cor Ligthert [MVP]

Craig,

Did you try use the sample FTP from the 101 2005 samples kit.

http://msdn.microsoft.com/vstudio/downloads/101samples/default.aspx

Be aware that this are often with a converter from C# converted samples
therefore don't use these as samples how to write VBNet programs. But they
are nice to learn the classes.

I hope this helps,

Cor

<craig.over***@gmail.com> schreef in bericht
Show quoteHide quote

news:1143061067.150353.250940@i39g2000cwa.googlegroups.com...
> All,
>
> I am currently developing an FTP class in VB.NET. It's kid tested,
> mother approved when trying to access an FTP Server on a Windows box
> meaning I can connect, run commands, upload and download a file no
> problem. My issues come when I try to use the same class with the same
> commands to access an FTP server on a UNIX box. I can connect and login
> just fine, but after that all my commands come back "500 'PWD': command
> not understood.". Has anyone experienced this error and can help me
> solve it. In order to help everyone out the following is my class:
>
> Imports System
> Imports System.Net
> Imports System.IO
> Imports System.Text
> Imports System.Text.ASCIIEncoding
> Imports System.Net.Sockets
> Imports System.Configuration
> Imports System.Resources
>
> Public Class FTPClient
>
> #Region "Local Properties"
>
>    '''<summary>
>    ''' Public Property: Host - String variable.
>    '''</summary>
>    Public Property Host() As String
>        Get
>            Return _Host
>        End Get
>        Set(ByVal Value As String)
>            _Host = Value
>        End Set
>    End Property
>
>    '''<summary>
>    ''' Public Property: Path - String variable.
>    '''</summary>
>    Public Property Path() As String
>        Get
>            Return _Path
>        End Get
>        Set(ByVal Value As String)
>            _Path = Value
>        End Set
>    End Property
>
>    '''<summary>
>    ''' Public Property: User - String variable.
>    '''</summary>
>    Public Property User() As String
>        Get
>            Return _User
>        End Get
>        Set(ByVal Value As String)
>            _User = Value
>        End Set
>    End Property
>
>    '''<summary>
>    ''' Public Property: Password - String variable.
>    '''</summary>
>    Public Property Password() As String
>        Get
>            Return _Password
>        End Get
>        Set(ByVal Value As String)
>            _Password = Value
>        End Set
>    End Property
>
>    '''<summary>
>    ''' Public Property: Port - String variable.
>    '''</summary>
>    Public Property Port() As String
>        Get
>            Return _Port
>        End Get
>        Set(ByVal Value As String)
>            _Port = Value
>        End Set
>    End Property
>
>    '''<summary>
>    ''' Public ReadOnly Property: ResponseCode - String variable.
>    '''</summary>
>    Public ReadOnly Property ResponseCode() As String
>        Get
>            Return _ResponseCode
>        End Get
>    End Property
>
>    '''<summary>
>    ''' Public ReadOnly Property: ResponseData - String variable.
>    '''</summary>
>    Public ReadOnly Property ResponseData() As String
>        Get
>            Return _ResponseData
>        End Get
>    End Property
>
> #End Region
>
>    ' FTP Default Properties.
>    Private _Host As String = "127.0.0.1"
>    Private _Path As String = "."
>    Private _User As String = "anonymous"
>    Private _Password As String = "anonym***@nowhere.com"
>    Private _Port As Integer = 21
>    Private _ResponseCode As Integer
>    Private _ResponseData As String
>    Private _FTPCommandSocket As Socket = Nothing
>    Private _FTPLogin As Boolean = False
>
> #Region "Public Methods"
>
>    Public Sub New()
>
>    End Sub
>
>    '''<summary>
>    ''' Public Function: Login - This function will create a command
> and data socket and then send the
>    ''' login credentials to the FTP host.
>    '''</summary>
>    '''<returns>Function returns a Boolean.</returns>
>    Public Function Login() As Boolean
>
>        ' Create an FTP command socket.
>        CreateCommandSocket()
>
>        ' Send the gathered login information to the FTP host.
>        Try
>            SendCommand("USER", _User)
>            SendCommand("PASS", _Password)
>            _FTPLogin = True
>        Catch ex As Exception
>            ' Login did not work because the FTP login information was
> not accepted.
>            _ResponseData = "FTP Login function not executed."
>            ' Throw New MPException(AppSettings.Item("Project"),
> "MP.IT.Web.Library.FTP - FTP login information was not accepted", ex)
>            Return False
>        End Try
>
>        ' Login successful.
>        Return True
>
>    End Function
>
>    '''<summary>
>    ''' Public Sub: Logout - This subroutine will disconnect and close
> an FTP command and data socket.
>    '''</summary>
>    '''<returns>Subroutine returns nothing.</returns>
>    Public Sub Logout()
>
>        ' Close and destroy the FTP command socket.
>        If (_FTPCommandSocket Is Nothing = False) Then
>            SendCommand("QUIT", "")
>            _FTPCommandSocket.Close()
>            _FTPCommandSocket = Nothing
>        End If
>    End Sub
>
>    '''<summary>
>    ''' Public Sub: SendCommand - Provided a Command and Arguements,
> this subroutine will execute an FTP Command.
>    ''' Commands already taken care of with subroutines below:
>    ''' TYPE:   Mode (ASCII or Binary)
>    ''' NLST:   List files in directory
>    ''' SIZE:   Get file Size
>    ''' RETR:   Download a file
>    ''' STOR:   Upload a file
>    ''' DELE:   Delete a file
>    ''' RNFR:   Select a file to be renamed
>    ''' RNTO:   Rename a selected file
>    ''' PWD:    Get a current directory
>    ''' CWD:    Change directory
>    ''' RDM:    Remove a directory
>    '''</summary>
>    '''<param name="FTPCommand">As String</param>
>    '''<param name="FTPCommandArguements">As String</param>
>    '''<returns>Function returns an FTP stream.</returns>
>    Public Sub SendCommand(ByVal FTPCommand As String, ByVal
> FTPCommandArguments As String)
>
>        ' Combine FTP command with the FTP command arguements.
>        Dim _FTPCommand As String = FTPCommand & " " &
> FTPCommandArguments
>        _FTPCommand += Environment.NewLine
>
>        ' Convert the FTP command into ASCII text.
>        Dim commandBytes() As Byte = ASCII.GetBytes(_FTPCommand)
>
>        Try
>            ' Execute the FTP command on the FTP host.
>            _FTPCommandSocket.Send(commandBytes, commandBytes.Length,
> 0)
>            ReadResponse()
>        Catch ex As Exception
>            ' Command was not executed.
>            _ResponseData = "FTP SendCommand subroutine not executed."
>            ' Throw New MPException(AppSettings.Item("Project"),
> "MP.IT.Web.Library.FTP - FTP command was not accepted", ex)
>        End Try
>    End Sub
>
>    '''<summary>
>    ''' Public Sub: SetBinaryMode - This subroutine sets the FTP mode
> to binary.
>    '''<param name="mode">As Boolean</param>
>    '''<returns>Subroutine returns nothing.</returns>
>    Public Sub SetBinaryMode(ByVal mode As Boolean)
>
>        If (mode) Then
>            'Send the FTP TYPE command as binary.
>            SendCommand("TYPE ", "I")
>        Else
>            'Send the FTP TYPE command as ASCII.
>            SendCommand("TYPE ", "A")
>        End If
>    End Sub
>
>    '''<summary>
>    ''' Public Function: GetDirectoryFileList - This function will get
> the names of the files from the provided directory name.
>    '''</summary>
>    '''<param name="directoryName">As String</param>
>    '''<returns>Function returns a string.</returns>
>    Public Function GetFileList(ByVal directoryName As String) As
> String()
>
>        ' Check to see if user is logged into FTP host.
>        If Not _FTPLogin Then
>            Login()
>        End If
>
>        ' Create an FTP data socket.
>        Dim _FTPDataSocket As Socket = CreateDataSocket()
>
>        'Send an FTP NLST command.
>        SendCommand("NLST ", directoryName)
>
>        Const _EndLine As Char = "\n"
>        Const _BufferSize As Integer = 512
>
>        Dim _Data As String = ""
>        Dim _Buffer(_BufferSize) As Byte
>        Dim _BytesRead As Integer = 0
>
>        If _FTPDataSocket.Connected Then
>            While (True)
>                Array.Clear(_Buffer, 0, _BufferSize)
>                _BytesRead = _FTPDataSocket.Receive(_Buffer,
> _Buffer.Length, 0)
>                _Data += ASCII.GetString(_Buffer, 0, _BytesRead)
>
>                If (_BytesRead < _Buffer.Length) Then Exit While
>            End While
>        Else
>            _ResponseData = "FTP data socket failed to connect."
>            ' Throw New MPException(AppSettings.Item("Project"),
> "MP.IT.Web.Library.FTP - GetFileList subroutine failed - FTP data
> socket failed to connect.", "")
>        End If
>
>        Dim _Parts() As String = _Data.Split(_EndLine)
>
>        ' Close and destroy the FTP data socket.
>        If (_FTPDataSocket Is Nothing = False) Then
>            _FTPDataSocket.Close()
>            _FTPDataSocket = Nothing
>        End If
>
>        Return _Parts
>
>    End Function
>
>    '''<summary>
>    ''' Public Function: GetFileSize - This function will get the size
> of a provided file name.
>    '''</summary>
>    '''<param name="fileName">As String</param>
>    '''<returns>Function returns a Long.</returns>
>    ' Get the size of the file on the FTP server.
>    Public Function GetFileSize(ByVal fileName As String) As Long
>
>        ' Check to see if user is logged into FTP host.
>        If Not _FTPLogin Then
>            Login()
>        End If
>
>        Dim _FileSize As Long
>
>        'Send an FTP SIZE command.
>        SendCommand("SIZE ", fileName)
>        _FileSize = 0
>
>        Return _FileSize = Int64.Parse(_ResponseData.Substring(4))
>
>    End Function
>
>    '''<summary>
>    ''' Public Sub: DownloadFile - This subroutine gets a specific
> file.
>    '''<param name="fileName">As String</param>
>    '''<param name="filePath">As String</param>
>    '''<optional param name="fileResume">As Boolean</param>
>    '''<returns>Subroutine returns nothing.</returns>
>    Public Sub DownloadFile(ByVal fileName As String, ByVal filePath As
> String, Optional ByVal fileResume As Boolean = False)
>
>        ' Check to see if user is logged into FTP host.
>        If Not _FTPLogin Then
>            Login()
>        End If
>
>        ' Set the FTP mode to binary.
>        SetBinaryMode(True)
>
>        ' Create an FTP data socket.
>        Dim _FTPDataSocket As Socket = CreateDataSocket()
>
>        ' Create a file.
>        Dim _FileStream As Stream
>        If (Not (File.Exists(filePath & fileName))) Then
>            _FileStream = File.Create(filePath & fileName)
>            _FileStream.Close()
>        End If
>
>        Dim _FTPFileStreamOutput As FileStream
>        _FTPFileStreamOutput = New FileStream(filePath & fileName,
> FileMode.Open)
>
>        If fileResume Then
>            Dim _FileOffset As Long
>            _FileOffset = _FTPFileStreamOutput.Length
>
>            If (_FileOffset > 0) Then
>                ' Send an FTP REST command to restart a file.
>                SendCommand("REST ", _FileOffset)
>                If (_ResponseCode <> 350) Then
>                    'The FTP host does not support resuming.
>                    _FileOffset = 0
>                End If
>            End If
>            If (_FileOffset <> 0) Then
>                _FTPFileStreamOutput.Seek(_FileOffset,
> SeekOrigin.Begin)
>            End If
>        End If
>
>        'Send an FTP RETR command to retrieve a file.
>        SendCommand("RETR ", fileName)
>
>        Const _EndLine As Char = "\n"
>        Const _BufferSize As Integer = 512
>
>        Dim _Data As String = ""
>        Dim _Buffer(_BufferSize) As Byte
>        Dim _BytesRead As Integer = 0
>
>        If _FTPDataSocket.Connected Then
>            While (True)
>                Array.Clear(_Buffer, 0, _BufferSize)
>                _BytesRead = _FTPDataSocket.Receive(_Buffer,
> _Buffer.Length, 0)
>                _FTPFileStreamOutput.Write(_Buffer, 0, _BytesRead)
>
>                If (_BytesRead < _Buffer.Length) Then Exit While
>            End While
>        Else
>            _ResponseData = "FTP data socket failed to connect."
>            ' Throw New MPException(AppSettings.Item("Project"),
> "MP.IT.Web.Library.FTP - GetFile subroutine failed - FTP data socket
> failed to connect.", "")
>        End If
>
>        _FTPFileStreamOutput.Close()
>
>        ' Close and destroy the FTP data socket.
>        If (_FTPDataSocket Is Nothing = False) Then
>            _FTPDataSocket.Close()
>            _FTPDataSocket = Nothing
>        End If
>
>    End Sub
>
>    '''<summary>
>    ''' Public Sub: UploadFile - This subroutine uploads a specific
> file to an FTP host.
>    '''<param name="fileName">As String</param>
>    '''<param name="filePath">As String</param>
>    '''<optional param name="fileResume">As Boolean</param>
>    '''<returns>Subroutine returns nothing.</returns>
>    Public Sub UploadFile(ByVal fileName As String, ByVal filePath As
> String, Optional ByVal fileResume As Boolean = False)
>
>        ' Check to see if user is logged into FTP host.
>        If Not _FTPLogin Then
>            Login()
>        End If
>
>        ' Set the FTP mode to binary.
>        SetBinaryMode(True)
>
>        ' Create an FTP data socket.
>        Dim _FTPDataSocket As Socket = CreateDataSocket()
>
>        ' Check to see if the file exists locally before the upload.
>        If (File.Exists(filePath & fileName)) Then
>
>            ' Open the input stream to read the source file.
>            Dim _FTPFileStreamInput As FileStream
>            _FTPFileStreamInput = New FileStream(filePath & fileName,
> FileMode.Open)
>
>            If fileResume Then
>                ' Check to see if part of the file has already been
> uploaded.
>                Dim _FileOffset As Long
>                _FileOffset = 0
>
>                Try
>                    _FileOffset = GetFileSize(fileName)
>                Catch ex As Exception
>                    _FileOffset = 0
>                End Try
>
>                If (_FileOffset > 0) Then
>                    ' Send an FTP REST command to restart a file.
>                    SendCommand("REST ", _FileOffset)
>                    If (_ResponseCode <> 350) Then
>                        'The FTP host does not support resuming.
>                        _FileOffset = 0
>                    End If
>                End If
>
>                If (_FileOffset <> 0) Then
>                    _FTPFileStreamInput.Seek(_FileOffset,
> SeekOrigin.Begin)
>                End If
>            End If
>
>            ' Send an FTP STOR command to store a file.
>            SendCommand("STOR ", fileName)
>
>            ' Upload the file.
>            Const _BufferSize As Integer = 512
>            Dim _Buffer(_BufferSize) As Byte
>            Dim _BytesRead As Integer = 0
>
>            _BytesRead = _FTPFileStreamInput.Read(_Buffer, 0,
> _Buffer.Length)
>            If _FTPDataSocket.Connected Then
>                While (_BytesRead > 0)
>                    _FTPDataSocket.Send(_Buffer, _BytesRead, 0)
>                    _BytesRead = _FTPFileStreamInput.Read(_Buffer, 0,
> _Buffer.Length)
>                End While
>
>            Else
>                    _ResponseData = "FTP data socket failed to
> connect."
>                    ' Throw New
> MPException(AppSettings.Item("Project"), "MP.IT.Web.Library.FTP -
> UploadFile subroutine failed - FTP data socket failed to connect.", "")
>            End If
>            _FTPFileStreamInput.Close()
>
>        Else
>            _ResponseData = "File to upload does not exist on local
> machine."
>            ' Throw New MPException(AppSettings.Item("Project"),
> "MP.IT.Web.Library.FTP - UploadFile subroutine failed - file to upload
> does not exist on local machine.", "")
>        End If
>
>        ' Close and destroy the FTP data socket.
>        If (_FTPDataSocket Is Nothing = False) Then
>            _FTPDataSocket.Close()
>            _FTPDataSocket = Nothing
>        End If
>
>    End Sub
>
>    '''<summary>
>    ''' Public Sub: UploadFile - This subroutine deletes a specific
> file on an FTP host.
>    '''<param name="fileName">As String</param>
>    '''<returns>Subroutine returns nothing.</returns>
>    Public Sub DeleteFile(ByVal fileName As String)
>
>        ' Check to see if user is logged into FTP host.
>        If Not _FTPLogin Then
>            Login()
>        End If
>
>        ' Send an FTP DELE command to delete a file.
>        SendCommand("DELE ", fileName)
>
>    End Sub
>
>    '''<summary>
>    ''' Public Sub: RenameFile - This subroutine renames a specific
> file on an FTP host.
>    '''<param name="fileName">As String</param>
>    '''<param name="fileNewName">As String</param>
>    '''<returns>Subroutine returns nothing.</returns>
>    Public Sub RenameFile(ByVal fileName As String, ByVal fileNewName
> As String)
>
>        ' Check to see if user is logged into FTP host.
>        If Not _FTPLogin Then
>            Login()
>        End If
>
>        ' Send an FTP RNFR command to select a file to be renamed.
>        SendCommand("RNFR ", fileName)
>
>        'Send an FTP RNTO command to rename the selected file to a new
> file name.
>        SendCommand("RNTO ", fileNewName)
>
>    End Sub
>
>    '''<summary>
>    ''' Public Sub: GetDirectory - This subroutine gets the current
> directory on an FTP host.
>    '''<returns>Subroutine returns nothing.</returns>
>    Public Sub GetDirectory()
>
>        ' Check to see if user is logged into FTP host.
>        If Not _FTPLogin Then
>            Login()
>        End If
>
>        'Send an FTP CWD command to change to a directory.
>        SendCommand("PWD ", "")
>
>    End Sub
>
>    '''<summary>
>    ''' Public Sub: ChangeDirectory - This subroutine changes to a
> directory on an FTP host.
>    '''<param name="directoryName">As String</param>
>    '''<returns>Subroutine returns nothing.</returns>
>    Public Sub ChangeDirectory(ByVal directoryName As String)
>
>        ' Check to see if user is logged into FTP host.
>        If Not _FTPLogin Then
>            Login()
>        End If
>
>        'Check if in the root directory.
>        If (directoryName.Equals(".")) Then
>            Exit Sub
>        End If
>
>        'Send an FTP CWD command to change to a directory.
>        SendCommand("CWD ", directoryName)
>
>    End Sub
>
>    '''<summary>
>    ''' Public Sub: CreateDirectory - This subroutine creates a new
> directory on an FTP host.
>    '''<param name="directoryName">As String</param>
>    '''<returns>Subroutine returns nothing.</returns>
>    Public Sub CreateDirectory(ByVal directoryName As String)
>
>        ' Check to see if user is logged into FTP host.
>        If Not _FTPLogin Then
>            Login()
>        End If
>
>        'Send an FTP MKD command to make a new directory.
>        SendCommand("MKD ", directoryName)
>
>    End Sub
>
>    '''<summary>
>    ''' Public Sub: RemoveDirectory - This subroutine removes a
> directory on an FTP host.
>    '''<param name="directoryName">As String</param>
>    '''<returns>Subroutine returns nothing.</returns>
>    Public Sub RemoveDirectory(ByVal directoryName As String)
>
>        ' Check to see if user is logged into FTP host.
>        If Not _FTPLogin Then
>            Login()
>        End If
>
>        'Send an FTP RMD command to remove a directory.
>        SendCommand("RMD ", directoryName)
>
>    End Sub
>
> #End Region
>
> #Region "Private Methods"
>
>    '''<summary>
>    ''' Private Sub: CreateCommandSocket - Provided a Host and a port
> this subroutine will instantiate an FTP command socket.
>    '''</summary>
>    '''<returns>Subroutine returns nothing.</returns>
>    Private Sub CreateCommandSocket()
>
>        ' Create the FTP command socket.
>        _FTPCommandSocket = New Socket(AddressFamily.InterNetwork,
> SocketType.Stream, ProtocolType.Tcp)
>
>        Try
>            Dim HostMachine As IPEndPoint = New
> IPEndPoint(Dns.Resolve(_Host).AddressList(0), _Port)
>            Try
>                ' Connect the FTP command socket to the FTP host
> machine.
>                _FTPCommandSocket.Connect(HostMachine)
>            Catch ex As Exception
>                ' Connection could not be opened due to malformed
> connection.
>                _ResponseData = "FTP Command Socket Connection Could
> Not Be Established."
>                ' Throw New MPException(AppSettings.Item("Project"),
> "MP.IT.Web.Library.FTP - FTP Command Socket Connection Could Not Be
> Established.", ex)
>            End Try
>        Catch ex As Exception
>            ' Connection could not be opened because DNS cannot resolve
> the host IP.
>            _ResponseData = "FTP Command Socket Connection Could Not Be
> Established. Connection could not be opened because DNS cannot resolve
> the host IP."
>            ' Throw New MPException(AppSettings.Item("Project"),
> "MP.IT.Web.Library.FTP - FTP Command Socket Connection Could Not Be
> Established. DNS cannot resolve the FTP host.", ex)
>        End Try
>        _ResponseData = "FTP Command Socket Connection Established."
>        ReadResponse()
>
>    End Sub
>
>    '''<summary>
>    ''' Private Function: CreateDataSocket - Provided that a PASV
> command has been sent to the host, this function returns
>    ''' an FTP data socket.
>    '''</summary>
>    '''<returns>Subroutine returns nothing.</returns>
>    Private Function CreateDataSocket() As Socket
>
>        Dim _FTPDataSocket As Socket
>        Dim _FTPHostIPFrontBracket As Integer
>        Dim _FTPHostIPBackBracket As Integer
>        Dim _FTPHostIPData As String
>        Dim _FTPHostIPLength As Integer
>        Dim _FTPHostIPPartCount As Integer
>        Dim _FTPHostIPParts(6) As Integer
>        Dim _FTPHostIPCharater As Char
>        Dim _Buffer As String
>        Dim _Counter As Integer
>
>        'Send an FTP PASV command to use passive data connection.
>        SendCommand("PASV", "")
>
>        _FTPHostIPFrontBracket = _ResponseData.IndexOf("(")
>        _FTPHostIPBackBracket = _ResponseData.IndexOf(")")
>        _FTPHostIPData = _ResponseData.Substring(_FTPHostIPFrontBracket
> + 1, _FTPHostIPBackBracket - _FTPHostIPFrontBracket - 1)
>
>        _FTPHostIPLength = _FTPHostIPData.Length
>        _FTPHostIPPartCount = 0
>        _Buffer = ""
>
>        For _Counter = 0 To ((_FTPHostIPLength - 1) And
> _FTPHostIPPartCount <= 6)
>            _FTPHostIPCharater =
> Char.Parse(_FTPHostIPData.Substring(_Counter, 1))
>            If (Char.IsDigit(_FTPHostIPCharater)) Then
>                _Buffer += _FTPHostIPCharater
>            ElseIf (_FTPHostIPCharater <> ",") Then
>                ' Throw New MPException(AppSettings.Item("Project"),
> "MP.IT.Web.Library.FTP - FTP Host did not accept the PASV command.",
> "")
>            End If
>
>            If ((_FTPHostIPCharater = ",") Or (_Counter + 1 =
> _FTPHostIPLength)) Then
>                Try
>                    _FTPHostIPParts(_FTPHostIPPartCount) =
> Int32.Parse(_Buffer)
>                    _FTPHostIPPartCount += 1
>                    _Buffer = ""
>                Catch ex As Exception
>                    ' Throw New
> MPException(AppSettings.Item("Project"), "MP.IT.Web.Library.FTP - FTP
> Host did not accept the PASV command.", ex)
>                End Try
>            End If
>        Next
>
>        ' Create the data host.
>        Dim _DataHost As String = _FTPHostIPParts(0) & "." &
> _FTPHostIPParts(1) & "." & _FTPHostIPParts(2) & "." &
> _FTPHostIPParts(3)
>
>        ' Create the data port.
>        Dim _DataPort As Integer = _FTPHostIPParts(4) << 8
>
>        ' Determine the data port number.
>        _DataPort = _DataPort + _FTPHostIPParts(5)
>
>        ' Create the FTP data socket from the data host and data port.
>        _FTPDataSocket = New Socket(AddressFamily.InterNetwork,
> SocketType.Stream, ProtocolType.Tcp)
>
>        Try
>            Dim HostMachine As IPEndPoint = New
> IPEndPoint(Dns.Resolve(_DataHost).AddressList(0), _DataPort)
>            Try
>                ' Connect the FTP data socket to the FTP host machine.
>                _FTPDataSocket.Connect(HostMachine)
>                Return _FTPDataSocket
>            Catch ex As Exception
>                ' Connection could not be opened due to malformed
> connection.
>                _ResponseData = "FTP Data Socket Connection Could Not
> Be Established."
>                ' Throw New MPException(AppSettings.Item("Project"),
> "MP.IT.Web.Library.FTP - FTP Data Socket Connection Could Not Be
> Established.", ex)
>            End Try
>        Catch ex As Exception
>            ' Connection could not be opened because DNS cannot resolve
> the host IP.
>            _ResponseData = "FTP Data Socket Connection Could Not Be
> Established. Connection could not be opened because DNS cannot resolve
> the host IP."
>            ' Throw New MPException(AppSettings.Item("Project"),
> "MP.IT.Web.Library.FTP - FTP Data Socket Connection Could Not Be
> Established. DNS cannot resolve the FTP host.", ex)
>        End Try
>        _ResponseData = "FTP Data Socket Connection Established."
>
>    End Function
>
>    '''<summary>
>    ''' Private Sub: ReadResponse - This subroutine will read line by
> line the reply to
>    ''' a command sent to an FTP host.
>    '''</summary>
>    '''<returns>Function returns a string.</returns>
>    Private Sub ReadResponse()
>
>        ' Read the response from the FTP host.
>        _ResponseData = ReadLine(False)
>        _ResponseCode = Int32.Parse(_ResponseData.Substring(0, 3))
>
>    End Sub
>
>    '''<summary>
>    ''' Private Function: ReadLine - This function handles the actual
> reading of the FTP host reply.
>    '''</summary>
>    '''<param name="clearResponse">As Boolean</param>
>    '''<returns>Function returns a string.</returns>
>    Private Function ReadLine(ByVal clearResponse As Boolean) As String
>
>        Const _EndLine As Char = "\n"
>        Const _BufferSize As Integer = 512
>
>        Dim _Data As String = ""
>        Dim _Buffer(_BufferSize) As Byte
>        Dim _BytesRead As Integer = 0
>
>        If (clearResponse = True) Then _ResponseData = String.Empty
>
>        While (True)
>            Array.Clear(_Buffer, 0, _BufferSize)
>            _BytesRead = _FTPCommandSocket.Receive(_Buffer,
> _Buffer.Length, 0)
>            _Data += ASCII.GetString(_Buffer, 0, _BytesRead)
>
>            If (_BytesRead < _Buffer.Length) Then Exit While
>        End While
>
>        Dim _Parts() As String = _Data.Split(_EndLine)
>
>        If (_Parts.Length > 2) Then
>            _ResponseData = _Parts(_Parts.Length - 2)
>        Else
>            _ResponseData = _Parts(0)
>        End If
>
>        If (_ResponseData.Substring(3, 1).Equals(" ") = False) Then
>            Return ReadLine(False)
>        End If
>
>        Return _ResponseData
>    End Function
>
> #End Region
>
> End Class
>