vb.net FTP Class

Yes I know later versions of Visual Basic after 1.1 include a built in FTP component. But here at GE we are still on 1.1 of the Framework (we have plans for the future to upgrade but we have had those a while now) So this is the FTP class I did here. It only contains generalized concepts because of security issues but it will serve you well if you need a FTP class.
 
Imports System
Imports System.Net
Imports System.IO
Imports System.Text
Imports System.Net.Sockets
Public Class FtpClient
  Private m_sRemoteHost, m_sRemotePath, m_sRemoteUser As String
  Private m_sRemotePassword, m_sMess As String
  Private m_iRemotePort, m_iBytes As Int32
  Private m_objClientSocket As Socket
  Private m_iRetValue As Int32
  Private m_bLoggedIn As Boolean
  Private m_sMes, m_sReply As String
  ‘Set the size of the packet that is used to read and to write data to the FTP server
  ‘to the following specified size.
  Public Const BLOCK_SIZE = 512
  Private m_aBuffer(BLOCK_SIZE) As Byte
  Private ASCII As Encoding = Encoding.ASCII
  Public flag_bool As Boolean
  ‘General variable declaration
  Private m_sMessageString As String
  ‘ Main class constructor
  Public Sub New()
    m_sRemoteHost = "microsoft"
    m_sRemotePath = "."
    m_sRemoteUser = "anonymous"
    m_sRemotePassword = ""
    m_sMessageString = ""
    m_iRemotePort = 21
    m_bLoggedIn = False
  End Sub
  ‘ Parameterized constructor
  Public Sub New(ByVal sRemoteHost As String, _
                 ByVal sRemotePath As String, _
                 ByVal sRemoteUser As String, _
                 ByVal sRemotePassword As String, _
                 ByVal iRemotePort As Int32)
    m_sRemoteHost = sRemoteHost
    m_sRemotePath = sRemotePath
    m_sRemoteUser = sRemoteUser
    m_sRemotePassword = sRemotePassword
    m_sMessageString = ""
    m_iRemotePort = 21
    m_bLoggedIn = False
  End Sub
  ‘Set or Get the name of the FTP server that you want to connect.
  Public Property RemoteHostFTPServer() As String
    ‘Get the name of the FTP server.
    Get
      Return m_sRemoteHost
    End Get
    ‘Set the name of the FTP server.
    Set(ByVal Value As String)
      m_sRemoteHost = Value
    End Set
  End Property
  ‘Set or Get the FTP Port Number of the FTP server that you want to connect.
  Public Property RemotePort() As Int32
    ‘Get the FTP Port Number.
    Get
      Return m_iRemotePort
    End Get
    ‘Set the FTP Port Number.
    Set(ByVal Value As Int32)
      m_iRemotePort = Value
    End Set
  End Property
  ‘Set or Get the remote path of the FTP server that you want to connect.
  Public Property RemotePath() As String
    ‘Get the remote path.
    Get
      Return m_sRemotePath
    End Get
    ‘Set the remote path.
    Set(ByVal Value As String)
      m_sRemotePath = Value
    End Set
  End Property
  ‘Set or Get the remote password of the FTP server that you want to connect.
  Public Property RemotePassword() As String
    Get
      Return m_sRemotePassword
    End Get
    Set(ByVal Value As String)
      m_sRemotePassword = Value
    End Set
  End Property
  ‘Set or Get the remote user of the FTP server that you want to connect.
  Public Property RemoteUser() As String
    Get
      Return m_sRemoteUser
    End Get
    Set(ByVal Value As String)
      m_sRemoteUser = Value
    End Set
  End Property
  ‘Set the class MessageString.
  Public Property MessageString() As String
    Get
      Return m_sMessageString
    End Get
    Set(ByVal Value As String)
      m_sMessageString = Value
    End Set
  End Property
  Public Function GetFileList() As String()
    Return GetFileList("")
  End Function
  ‘Return a list of files in a string() array from the file system.
  Public Function GetFileList(ByVal sMask As String) As String()
    Dim cSocket As Socket
    Dim bytes As Int32
    Dim seperator As Char = ControlChars.Lf
    Dim mess() As String
    m_sMes = ""
    ‘Check if you are logged on to the FTP server.
    If (Not (m_bLoggedIn)) Then
      Login()
    End If
    cSocket = CreateDataSocket()
    ‘Send an FTP command,
    If sMask & "" = "" Then
      SendCommand("NLST")
    Else
      SendCommand("NLST " & sMask)
    End If
    If (Not (m_iRetValue = 150 Or m_iRetValue = 125)) Then
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
    m_sMes = ""
    Do While (True)
      m_aBuffer.Clear(m_aBuffer, 0, m_aBuffer.Length)
      bytes = cSocket.Receive(m_aBuffer, m_aBuffer.Length, 0)
      m_sMes += ASCII.GetString(m_aBuffer, 0, bytes)
      If (bytes < m_aBuffer.Length) Then
        Exit Do
      End If
    Loop
    mess = m_sMes.Split(seperator)
    cSocket.Close()
    ReadReply()
    If (m_iRetValue <> 226) Then
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
    Return mess
  End Function
  ‘ Get the size of the file on the FTP server.
  Public Function GetFileSize(ByVal sFileName As String) As Long
    Dim size As Long
    If (Not (m_bLoggedIn)) Then
      Login()
    End If
    ‘Send an FTP command.
    SendCommand("SIZE " & sFileName)
    size = 0
    If (m_iRetValue = 213) Then
      size = Int64.Parse(m_sReply.Substring(4))
    Else
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
    Return size
  End Function
  ‘Log on to the FTP server.
  Public Function Login() As Boolean
    m_objClientSocket = _
    New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
    Dim ep As New IPEndPoint(Dns.Resolve(m_sRemoteHost).AddressList(0), m_iRemotePort)
    Try
      m_objClientSocket.Connect(ep)
    Catch ex As Exception
      MessageString = m_sReply
      Throw New IOException("Cannot connect to remote server")
    End Try
    ReadReply()
    If (m_iRetValue <> 220) Then
      CloseConnection()
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
    ‘Send an FTP command to send a user logon ID to the server.
    SendCommand("USER " & m_sRemoteUser)
    If (Not (m_iRetValue = 331 Or m_iRetValue = 230)) Then
      Cleanup()
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
    If (m_iRetValue <> 230) Then
      ‘Send an FTP command to send a user logon password to the server.
      SendCommand("PASS " & m_sRemotePassword)
      If (Not (m_iRetValue = 230 Or m_iRetValue = 202)) Then
        Cleanup()
        MessageString = m_sReply
        Throw New IOException(m_sReply.Substring(4))
      End If
    End If
    m_bLoggedIn = True
    ‘Call the ChangeDirectory user-defined function to change the folder to the
    ‘remote FTP folder that is mapped.
    ChangeDirectory(m_sRemotePath)
    ‘Return the final result.
    Return m_bLoggedIn
  End Function
  ‘If the value of mode is true, set the binary mode for downloads. Otherwise, set ASCII mode.
  Public Sub SetBinaryMode(ByVal bMode As Boolean)
    If (bMode) Then
      ‘Send the FTP command to set the binary mode.
      ‘(TYPE is an FTP command that is used to specify representation type.)
      SendCommand("TYPE I")
    Else
      ‘Send the FTP command to set ASCII mode.
      ‘(TYPE is a FTP command that is used to specify representation type.)
      SendCommand("TYPE A")
    End If
    If (m_iRetValue <> 200) Then
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
  End Sub
  ‘ Download a file to the local folder of the assembly, and keep the same file name.
  Public Sub DownloadFile(ByVal sFileName As String)
    DownloadFile(sFileName, "", False)
  End Sub
  ‘ Download a remote file to the local folder of the assembly, and keep the same file name.
  Public Sub DownloadFile(ByVal sFileName As String, _
                          ByVal bResume As Boolean)
    DownloadFile(sFileName, "", bResume)
  End Sub
  ‘Download a remote file to a local file name. You must include a path.
  ‘The local file name will be created or will be overwritten, but the path must exist.
  Public Sub DownloadFile(ByVal sFileName As String, _
                          ByVal sLocalFileName As String)
    DownloadFile(sFileName, sLocalFileName, False)
  End Sub
  ‘ Download a remote file to a local file name and include a path. Then, set the
  ‘ resume flag. The local file name will be created or will be overwritten, but the path must exist.
  Public Sub DownloadFile(ByVal sFileName As String, _
                          ByVal sLocalFileName As String, _
                          ByVal bResume As Boolean)
    Dim st As Stream
    Dim output As FileStream
    Dim cSocket As Socket
    Dim offset, npos As Long
    If (Not (m_bLoggedIn)) Then
      Login()
    End If
    SetBinaryMode(True)
    If (sLocalFileName.Equals("")) Then
      sLocalFileName = sFileName
    End If
    If (Not (File.Exists(sLocalFileName))) Then
      st = File.Create(sLocalFileName)
      st.Close()
    End If
    output = New FileStream(sLocalFileName, FileMode.Open)
    cSocket = CreateDataSocket()
    offset = 0
    If (bResume) Then
      offset = output.Length
      If (offset > 0) Then
        ‘Send an FTP command to restart.
        SendCommand("REST " & offset)
        If (m_iRetValue <> 350) Then
          offset = 0
        End If
      End If
      If (offset > 0) Then
        npos = output.Seek(offset, SeekOrigin.Begin)
      End If
    End If
    ‘Send an FTP command to retrieve a file.
    SendCommand("RETR " & sFileName)
    If (Not (m_iRetValue = 150 Or m_iRetValue = 125)) Then
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
    Do While (True)
      m_aBuffer.Clear(m_aBuffer, 0, m_aBuffer.Length)
      m_iBytes = cSocket.Receive(m_aBuffer, m_aBuffer.Length, 0)
      output.Write(m_aBuffer, 0, m_iBytes)
      If (m_iBytes <= 0) Then
        Exit Do
      End If
    Loop
    output.Close()
    If (cSocket.Connected) Then
      cSocket.Close()
    End If
    ReadReply()
    If (Not (m_iRetValue = 226 Or m_iRetValue = 250)) Then
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
  End Sub
  ‘ This is a function that is used to upload a file from your local hard disk to your FTP site.
  Public Sub UploadFile(ByVal sFileName As String)
    UploadFile(sFileName, False)
  End Sub
  ‘ This is a function that is used to upload a file from your local hard disk to your FTP site
  ‘ and then set the resume flag.
  Public Sub UploadFile(ByVal sFileName As String, _
                        ByVal bResume As Boolean)
    Dim cSocket As Socket
    Dim offset As Long
    Dim input As FileStream
    Dim bFileNotFound As Boolean
    If (Not (m_bLoggedIn)) Then
      Login()
    End If
    cSocket = CreateDataSocket()
    offset = 0
    If (bResume) Then
      Try
        SetBinaryMode(True)
        offset = GetFileSize(sFileName)
      Catch ex As Exception
        offset = 0
      End Try
    End If
    If (offset > 0) Then
      SendCommand("REST " & offset)
      If (m_iRetValue <> 350) Then
        ‘The remote server may not support resuming.
        offset = 0
      End If
    End If
    ‘Send an FTP command to store a file.
    SendCommand("STOR " & Path.GetFileName(sFileName))
    If (Not (m_iRetValue = 125 Or m_iRetValue = 150)) Then
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
    ‘Check to see if the file exists before the upload.
    bFileNotFound = False
    If (File.Exists(sFileName)) Then
      ‘ Open the input stream to read the source file.
      input = New FileStream(sFileName, FileMode.Open)
      If (offset <> 0) Then
        input.Seek(offset, SeekOrigin.Begin)
      End If
      ‘Upload the file.
      m_iBytes = input.Read(m_aBuffer, 0, m_aBuffer.Length)
      Do While (m_iBytes > 0)
        cSocket.Send(m_aBuffer, m_iBytes, 0)
        m_iBytes = input.Read(m_aBuffer, 0, m_aBuffer.Length)
      Loop
      input.Close()
    Else
      bFileNotFound = True
    End If
    If (cSocket.Connected) Then
      cSocket.Close()
    End If
    ‘Check the return value if the file was not found.
    If (bFileNotFound) Then
      MessageString = m_sReply
      Throw New IOException("The file: " & sFileName & " was not found." & _
      " Cannot upload the file to the FTP site.")
    End If
    ReadReply()
    If (Not (m_iRetValue = 226 Or m_iRetValue = 250)) Then
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
  End Sub
  ‘ Delete a file from the remote FTP server.
  Public Function DeleteFile(ByVal sFileName As String) As Boolean
    Dim bResult As Boolean
    bResult = True
    If (Not (m_bLoggedIn)) Then
      Login()
    End If
    ‘Send an FTP command to delete a file.
    SendCommand("DELE " & sFileName)
    If (m_iRetValue <> 250) Then
      bResult = False
      MessageString = m_sReply
    End If
    ‘ Return the final result.
    Return bResult
  End Function
  ‘ Rename a file on the remote FTP server.
  Public Function RenameFile(ByVal sOldFileName As String, _
                             ByVal sNewFileName As String) As Boolean
    Dim bResult As Boolean
    bResult = True
    If (Not (m_bLoggedIn)) Then
      Login()
    End If
    ‘Send an FTP command to rename a file.
    SendCommand("RNFR " & sOldFileName)
    If (m_iRetValue <> 350) Then
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
    ‘Send an FTP command to rename a file to a file name.
    ‘It will overwrite if newFileName exists.
    SendCommand("RNTO " & sNewFileName)
    If (m_iRetValue <> 250) Then
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
    ‘ Return the final result.
    Return bResult
  End Function
  ‘This is a function that is used to create a folder on the remote FTP server.
  Public Function CreateDirectory(ByVal sDirName As String) As Boolean
    Dim bResult As Boolean
    bResult = True
    If (Not (m_bLoggedIn)) Then
      Login()
    End If
    ‘Send an FTP command to make a folder on the FTP server.
    SendCommand("MKD " & sDirName)
    If (m_iRetValue <> 257) Then
      bResult = False
      MessageString = m_sReply
    End If
    ‘ Return the final result.
    Return bResult
  End Function
  ‘ This is a function that is used to delete a folder on the remote FTP server.
  Public Function RemoveDirectory(ByVal sDirName As String) As Boolean
    Dim bResult As Boolean
    bResult = True
    ‘Check if you are logged on to the FTP server.
    If (Not (m_bLoggedIn)) Then
      Login()
    End If
    ‘Send an FTP command to remove a folder on the FTP server.
    SendCommand("RMD " & sDirName)
    If (m_iRetValue <> 250) Then
      bResult = False
      MessageString = m_sReply
    End If
    ‘ Return the final result.
    Return bResult
  End Function
  ‘This is a function that is used to change the current working folder on the remote FTP server.
  Public Function ChangeDirectory(ByVal sDirName As String) As Boolean
    Dim bResult As Boolean
    bResult = True
    ‘Check if you are in the root directory.
    If (sDirName.Equals(".")) Then
      Exit Function
    End If
    ‘Check if you are logged on to the FTP server.
    If (Not (m_bLoggedIn)) Then
      Login()
    End If
    ‘Send an FTP command to change the folder on the FTP server.
    SendCommand("CWD " & sDirName)
    If (m_iRetValue <> 250) Then
      bResult = False
      MessageString = m_sReply
    End If
    Me.m_sRemotePath = sDirName
    ‘ Return the final result.
    Return bResult
  End Function
  ‘ Close the FTP connection of the remote server.
  Public Sub CloseConnection()
    If (Not (m_objClientSocket Is Nothing)) Then
      ‘Send an FTP command to end an FTP server system.
      SendCommand("QUIT")
    End If
    Cleanup()
  End Sub
  ‘ Read the reply from the FTP server.
  Private Sub ReadReply()
    m_sMes = ""
    m_sReply = ReadLine()
    m_iRetValue = Int32.Parse(m_sReply.Substring(0, 3))
  End Sub
  ‘ Clean up some variables.
  Private Sub Cleanup()
    If Not (m_objClientSocket Is Nothing) Then
      m_objClientSocket.Close()
      m_objClientSocket = Nothing
    End If
    m_bLoggedIn = False
  End Sub
  ‘ Read a line from the FTP server.
  Private Function ReadLine(Optional ByVal bClearMes As Boolean = False) As String
    Dim seperator As Char = ControlChars.Lf
    Dim mess() As String
    If (bClearMes) Then
      m_sMes = ""
    End If
    Do While (True)
      m_aBuffer.Clear(m_aBuffer, 0, BLOCK_SIZE)
      m_iBytes = m_objClientSocket.Receive(m_aBuffer, m_aBuffer.Length, 0)
      m_sMes += ASCII.GetString(m_aBuffer, 0, m_iBytes)
      If (m_iBytes < m_aBuffer.Length) Then
        Exit Do
      End If
    Loop
    mess = m_sMes.Split(seperator)
    If (m_sMes.Length > 2) Then
      m_sMes = mess(mess.Length – 2)
    Else
      m_sMes = mess(0)
    End If
    If (Not (m_sMes.Substring(3, 1).Equals(" "))) Then
      Return ReadLine(True)
    End If
    Return m_sMes
  End Function
  ‘ This is a function that is used to send a command to the FTP server that you are connected to.
  Private Sub SendCommand(ByVal sCommand As String)
    sCommand = sCommand & ControlChars.CrLf
    Dim cmdbytes As Byte() = ASCII.GetBytes(sCommand)
    m_objClientSocket.Send(cmdbytes, cmdbytes.Length, 0)
    ReadReply()
  End Sub
  ‘ Create a data socket.
  Private Function CreateDataSocket() As Socket
    Dim index1, index2, len As Int32
    Dim partCount, i, port As Int32
    Dim ipData, buf, ipAddress As String
    Dim parts(6) As Int32
    Dim ch As Char
    Dim s As Socket
    Dim ep As IPEndPoint
    ‘Send an FTP command to use a passive data connection.
    SendCommand("PASV")
    If (m_iRetValue <> 227) Then
      MessageString = m_sReply
      Throw New IOException(m_sReply.Substring(4))
    End If
    index1 = m_sReply.IndexOf("(")
    index2 = m_sReply.IndexOf(")")
    ipData = m_sReply.Substring(index1 + 1, index2 – index1 – 1)
    len = ipData.Length
    partCount = 0
    buf = ""
    For i = 0 To ((len – 1) And partCount <= 6)
      ch = Char.Parse(ipData.Substring(i, 1))
      If (Char.IsDigit(ch)) Then
        buf += ch
      ElseIf (ch <> ",") Then
        MessageString = m_sReply
        Throw New IOException("Malformed PASV reply: " & m_sReply)
      End If
      If ((ch = ",") Or (i + 1 = len)) Then
        Try
          parts(partCount) = Int32.Parse(buf)
          partCount += 1
          buf = ""
        Catch ex As Exception
          MessageString = m_sReply
          Throw New IOException("Malformed PASV reply: " & m_sReply)
        End Try
      End If
    Next
    ipAddress = parts(0) & "." & parts(1) & "." & parts(2) & "." & parts(3)
    ‘ Make this call in Visual Basic .NET 2002.  You want to
    ‘ bitshift the number by 8 bits. Therefore, in Visual Basic .NET 2002, you must
    ‘ multiply the number by 2 to the power of 8.
    ‘port = parts(4) * (2 ^ 8)
    ‘ Make this call and then comment out the previous line for Visual Basic .NET 2003.
    port = parts(4) << 8
    ‘ Determine the data port number.
    port = port + parts(5)
    s = New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
    ep = New IPEndPoint(Dns.Resolve(ipAddress).AddressList(0), port)
    Try
      s.Connect(ep)
    Catch ex As Exception
      MessageString = m_sReply
      Throw New IOException("Cannot connect to remote server")
      ‘If you cannot connect to the FTP
      ‘server that is specified, make the boolean variable false.
      flag_bool = False
    End Try
    ‘If you can connect to the FTP server that is specified, make the boolean variable true.
    flag_bool = True
    Return s
  End Function
End Class

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