FTP using VB.NET

It was not my initial intention to share how to code FTP library. Initially, I thought .NET has already supplied complete library for ftp. However, I got a big "NOT!".

While you are able to do download and upload files via FTP using System.Net.FtpWebRequest -creating, renaming and deleting folder was not so straight forward. You still have to go back to the basic ftp command such as MKD, RNFR, RMD, etc.

I finally came across a library that did this library in C# codes .

This library will enable you to do few important actions such as:
1 - Connect to FTP server (for sure!)
2 - upload file
3 - download file
4 - delete remote file
4 - create remote folder
5 - delete remote folder
6 - rename remote folder
7 - list down all the files in the remote path
8 - get remote file size

All these functions should be enough to develop one powerful FTP client.

I've spent couple of hours to translate this code into VB.NET and done some modifications to make this library works for me, then this is the result. (quite a long code)

**********************************************************************************


Imports System
Imports System.Net
Imports System.IO
Imports System.Text
Imports System.Net.Sockets

Public Class FTPClass
Private remoteHost As String, remotePath As String, remoteUser As String, remotePass As String, mes As String
Private remotePort As Integer, bytes As Integer
Private clientSocket As Socket
Private retValue As Integer
Private debug As Boolean
Private logined As Boolean
Private reply As String
Private Shared BLOCK_SIZE As Integer = 512
Private buffer As Byte() = New Byte(BLOCK_SIZE - 1) {}
Private ASCII As Encoding = Encoding.ASCII
Public Sub New()
remoteHost = "192.168.X.XX" 'Please specify correct IP
remotePath = "."
remoteUser = "username"
remotePass =  "password"
remotePort = 21
debug = False
logined = False
End Sub
'''
''' Set the name of the FTP server to connect to.
'''
''' Server name
Public Sub setRemoteHost(ByVal remoteHost As String)
Me.remoteHost = remoteHost
End Sub
'''
''' Return the name of the current FTP server.
'''
''' Server name
Public Function getRemoteHost() As String
Return remoteHost
End Function
'''
''' Set the port number to use for FTP.
'''
''' Port number
Public Sub setRemotePort(ByVal remotePort As Integer)
Me.remotePort = remotePort
End Sub
'''
''' Return the current port number.
'''
''' Current port number
Public Function getRemotePort() As Integer
Return remotePort
End Function
'''
''' Set the remote directory path.
'''
''' The remote directory path
Public Sub setRemotePath(ByVal remotePath As String)
Me.remotePath = remotePath
End Sub
'''
''' Return the current remote directory path.
'''
''' The current remote directory path.
Public Function getRemotePath() As String
Return remotePath
End Function
'''
''' Set the user name to use for logging into the remote server.
'''
''' Username
Public Sub setRemoteUser(ByVal remoteUser As String)
Me.remoteUser = remoteUser
End Sub
'''
''' Set the password to user for logging into the remote server.
'''
''' Password
Public Sub setRemotePass(ByVal remotePass As String)
Me.remotePass = remotePass
End Sub
'''
''' Return a string array containing the remote directory's file list.
'''
'''
'''
Public Function getFileList(ByVal mask As String) As String()
If Not logined Then
login()
End If
Dim cSocket As Socket = createDataSocket()
sendCommand("NLST " & mask)
If Not (retValue = 150 OrElse retValue = 125) Then
Throw New IOException(reply.Substring(4))
End If
mes = ""
While True
Dim bytes As Integer = cSocket.Receive(buffer, buffer.Length, 0)
mes += ASCII.GetString(buffer, 0, bytes)
If bytes < buffer.Length Then
Exit While
End If
End While
Dim seperator As Char() = {ControlChars.Lf}
Dim mess As String() = mes.Split(seperator)
cSocket.Close()
readReply()
If retValue <> 226 Then
Throw New IOException(reply.Substring(4))
End If
Return mess
End Function
'''
''' Return the size of a file.
'''
'''
'''
Public Function getFileSize(ByVal fileName As String) As Long
If Not logined Then
login()
End If
sendCommand("SIZE " & fileName)
Dim size As Long = 0
If retValue = 213 Then
size = Int64.Parse(reply.Substring(4))
Else
Throw New IOException(reply.Substring(4))
End If
Return size
End Function
'''
''' Login to the remote server.
'''
Public Sub login()
clientSocket = New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
Dim ep As New IPEndPoint(Dns.Resolve(remoteHost).AddressList(0), remotePort)
Try
clientSocket.Connect(ep)
Catch generatedExceptionName As Exception
Throw New IOException("Couldn't connect to remote server")
End Try
readReply()
If retValue <> 220 Then
close()
Throw New IOException(reply.Substring(4))
End If
If debug Then
Console.WriteLine("USER " & remoteUser)
End If
sendCommand("USER " & remoteUser)
If Not (retValue = 331 OrElse retValue = 230) Then
cleanup()
Throw New IOException(reply.Substring(4))
End If
If retValue <> 230 Then
If debug Then
Console.WriteLine("PASS xxx")
End If
sendCommand("PASS " & remotePass)
If Not (retValue = 230 OrElse retValue = 202) Then
cleanup()
Throw New IOException(reply.Substring(4))
End If
End If
logined = True
Console.WriteLine("Connected to " & remoteHost)
chdir(remotePath)
End Sub
'''
''' If the value of mode is true, set binary mode for downloads.
''' Else, set Ascii mode.
'''
'''
Public Sub setBinaryMode(ByVal mode As Boolean)
If mode Then
sendCommand("TYPE I")
Else
sendCommand("TYPE A")
End If
If retValue <> 200 Then
Throw New IOException(reply.Substring(4))
End If
End Sub
'''
''' Download a file to the Assembly's local directory,
''' keeping the same file name.
'''
'''
Public Sub download(ByVal remFileName As String)
download(remFileName, "", False)
End Sub
'''
''' Download a remote file to the Assembly's local directory,
''' keeping the same file name, and set the resume flag.
'''
'''
'''
Public Sub download(ByVal remFileName As String, ByVal [resume] As Boolean)
download(remFileName, "", [resume])
End Sub
'''
''' Download a remote file to a local file name which can include
''' a path. The local file name will be created or overwritten,
''' but the path must exist.
'''
'''
'''
Public Sub download(ByVal remFileName As String, ByVal locFileName As String)
download(remFileName, locFileName, False)
End Sub
'''
''' Download a remote file to a local file name which can include
''' a path, and set the resume flag. The local file name will be
''' created or overwritten, but the path must exist.
'''
'''
'''
'''
Public Sub download(ByVal remFileName As String, ByVal locFileName As String, ByVal [resume] As Boolean)
If Not logined Then
login()
End If
setBinaryMode(True)
Console.WriteLine((("Downloading file " & remFileName & " from ") + remoteHost & "/") + remotePath)
If locFileName.Equals("") Then
locFileName = remFileName
End If
If Not File.Exists(locFileName) Then
Dim st As Stream = File.Create(locFileName)
st.Close()
End If
Dim output As New FileStream(locFileName, FileMode.Open)
Dim cSocket As Socket = createDataSocket()
Dim offset As Long = 0
If [resume] Then
offset = output.Length
If offset > 0 Then
sendCommand("REST " & offset)
If retValue <> 350 Then
'throw new IOException(reply.Substring(4));
'Some servers may not support resuming.
offset = 0
End If
End If
If offset > 0 Then
If debug Then
Console.WriteLine("seeking to " & offset)
End If
Dim npos As Long = output.Seek(offset, SeekOrigin.Begin)
Console.WriteLine("new pos=" & npos)
End If
End If
sendCommand("RETR " & remFileName)
If Not (retValue = 150 OrElse retValue = 125) Then
Throw New IOException(reply.Substring(4))
End If
While True
bytes = cSocket.Receive(buffer, buffer.Length, 0)
output.Write(buffer, 0, bytes)
If bytes <= 0 Then
Exit While
End If
End While
output.Close()
If cSocket.Connected Then
cSocket.Close()
End If
Console.WriteLine("")
readReply()
If Not (retValue = 226 OrElse retValue = 250) Then
Throw New IOException(reply.Substring(4))
End If
End Sub
'''
''' Upload a file.
'''
'''
Public Sub upload(ByVal fileName As String)
upload(fileName, False)
End Sub
'''
''' Upload a file and set the resume flag.
'''
'''
'''
Public Sub upload(ByVal fileName As String, ByVal [resume] As Boolean)
If Not logined Then
login()
End If
Dim cSocket As Socket = createDataSocket()
Dim offset As Long = 0
If [resume] Then
Try
setBinaryMode(True)
offset = getFileSize(fileName)
Catch generatedExceptionName As Exception
offset = 0
End Try
End If
If offset > 0 Then
sendCommand("REST " & offset)
If retValue <> 350 Then
'throw new IOException(reply.Substring(4));
'Remote server may not support resuming.
offset = 0
End If
End If
sendCommand("STOR " & Path.GetFileName(fileName))
If Not (retValue = 125 OrElse retValue = 150) Then
Throw New IOException(reply.Substring(4))
End If
' open input stream to read source file
Dim input As New FileStream(fileName, FileMode.Open)
If offset <> 0 Then
If debug Then
Console.WriteLine("seeking to " & offset)
End If
input.Seek(offset, SeekOrigin.Begin)
End If
Console.WriteLine(("Uploading file " & fileName & " to ") + remotePath)
While (InlineAssignHelper(bytes, input.Read(buffer, 0, buffer.Length))) > 0
cSocket.Send(buffer, bytes, 0)
End While
input.Close()
Console.WriteLine("")
If cSocket.Connected Then
cSocket.Close()
End If
readReply()
If Not (retValue = 226 OrElse retValue = 250) Then
Throw New IOException(reply.Substring(4))
End If
End Sub
'''
''' Delete a file from the remote FTP server.
'''
'''
Public Sub deleteRemoteFile(ByVal fileName As String)
If Not logined Then
login()
End If
sendCommand("DELE " & fileName)
If retValue <> 250 Then
Throw New IOException(reply.Substring(4))
End If
End Sub
'''
''' Rename a file on the remote FTP server.
'''
'''
'''
Public Sub renameRemoteFile(ByVal oldFileName As String, ByVal newFileName As String)
If Not logined Then
login()
End If
sendCommand("RNFR " & oldFileName)
If retValue <> 350 Then
Throw New IOException(reply.Substring(4))
End If
' known problem
' rnto will not take care of existing file.
' i.e. It will overwrite if newFileName exist
sendCommand("RNTO " & newFileName)
If retValue <> 250 Then
Throw New IOException(reply.Substring(4))
End If
End Sub
'''
''' Create a directory on the remote FTP server.
'''
'''
Public Sub mkdir(ByVal dirName As String)
If Not logined Then
login()
End If
sendCommand("MKD " & dirName)
If retValue > 400 Then
Throw New IOException(reply.Substring(4))
End If
End Sub
'''
''' Delete a directory on the remote FTP server.
'''
'''
Public Sub rmdir(ByVal dirName As String)
If Not logined Then
login()
End If
sendCommand("RMD " & dirName)
If retValue <> 250 Then
Throw New IOException(reply.Substring(4))
End If
End Sub
'''
''' Change the current working directory on the remote FTP server.
'''
'''
Public Sub chdir(ByVal dirName As String)
If dirName.Equals(".") Then
Exit Sub
End If
If Not logined Then
login()
End If
sendCommand("CWD " & dirName)
If retValue <> 250 Then
Throw New IOException(reply.Substring(4))
End If
Me.remotePath = dirName
Console.WriteLine("Current directory is " & remotePath)
End Sub
'''
''' Close the FTP connection.
'''
Public Sub close()
If clientSocket IsNot Nothing Then
sendCommand("QUIT")
End If
cleanup()
Console.WriteLine("Closing...")
End Sub
'''
''' Set debug mode.
'''
'''
Public Sub setDebug(ByVal debug As Boolean)
Me.debug = debug
End Sub
Private Sub readReply()
mes = ""
reply = readLine()
retValue = Int32.Parse(reply.Substring(0, 3))
End Sub
Private Sub cleanup()
If clientSocket IsNot Nothing Then
clientSocket.Close()
clientSocket = Nothing
End If
logined = False
End Sub
Private Function readLine() As String
While True
bytes = clientSocket.Receive(buffer, buffer.Length, 0)
mes += ASCII.GetString(buffer, 0, bytes)
If bytes < buffer.Length Then
Exit While
End If
End While
Dim seperator As Char() = {ControlChars.Lf}
Dim mess As String() = mes.Split(seperator)
If mes.Length > 2 Then
mes = mess(mess.Length - 2)
Else
mes = mess(0)
End If
If Not mes.Substring(3, 1).Equals(" ") Then
Return readLine()
End If
If debug Then
For k As Integer = 0 To mess.Length - 2
Console.WriteLine(mess(k))
Next
End If
Return mes
End Function
Private Sub sendCommand(ByVal command As String)
Dim cmdBytes As Byte() = Encoding.ASCII.GetBytes((command & vbCr & vbLf).ToCharArray())
clientSocket.Send(cmdBytes, cmdBytes.Length, 0)
readReply()
End Sub
Private Function createDataSocket() As Socket
sendCommand("PASV")
If retValue <> 227 Then
Throw New IOException(reply.Substring(4))
End If
Dim index1 As Integer = reply.IndexOf("("c)
Dim index2 As Integer = reply.IndexOf(")"c)
Dim ipData As String = reply.Substring(index1 + 1, index2 - index1 - 1)
Dim parts As Integer() = New Integer(5) {}
Dim len As Integer = ipData.Length
Dim partCount As Integer = -1
Dim buf As String = ""
Dim i As Integer = 0
While i < len AndAlso partCount <= 6
Dim ch As Char = [Char].Parse(ipData.Substring(i, 1))
If [Char].IsDigit(ch) Then
buf += ch
ElseIf ch <> ","c Then
Throw New IOException("Malformed PASV reply: " & reply)
End If
If ch = ","c OrElse i + 1 = len Then
Try
parts(System.Math.Max(System.Threading.Interlocked.Increment(partCount), partCount - 1)) = Int32.Parse(buf)
buf = ""
Catch generatedExceptionName As Exception
Throw New IOException("Malformed PASV reply: " & reply)
End Try
End If
i += 1
End While
Dim ipAddress As String = (((CStr(parts(0)) & ".") + CStr(parts(1)) & ".") + CStr(parts(2)) & ".") + CStr(parts(3))
Dim port As Integer = (parts(4) << 8) + parts(5)
Dim s As New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
Dim ep As New IPEndPoint(Dns.Resolve(ipAddress).AddressList(0), port)
Try
s.Connect(ep)
Catch generatedExceptionName As Exception
Throw New IOException("Can't connect to remote server")
End Try
Return s
End Function
Private Shared Function InlineAssignHelper(Of T)(ByRef target As T, ByVal value As T) As T
target = value
Return value
End Function
End Class
To call this class, you can do like this:

Private Function UploadFile() As Boolean

Dim ft As New FTPClass
Try
ft.setDebug(True)
ft.setRemoteHost("192.168.1.87")
ft.setRemoteUser("user")
ft.setRemotePass("123456")
ft.setRemotePath("Root/")
ft.setRemotePort(21)

ft.login()
Try
ft.chdir("Test")
Catch ex As Exception
Finally
ft.mkdir("Test")
End Try
ft.chdir("Test")

ft.setRemotePath("test.txt")
ft.setBinaryMode(True)
ft.upload("C:\test.txt")
ft.close()
Catch ex As Exception
ft.close()
MsgBox(ex.Message)
Return False
End Try
MsgBox("Upload success!")
Return True
End Function


****