Knowledge Base
How to access a File Transfer Protocol site by using Visual Basic .NETPSS ID Number: 832679
Article Last Modified on 1/20/2004
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The information in this article applies to:
Microsoft Visual Basic .NET (2003)
Microsoft Visual Basic .NET (2002)
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IN THIS TASK
SUMMARY
Requirements
Add references, and declare class variables
Define class constructors
Set public properties
Use the public sub-procedures and the public functions
Use the private sub-procedures and the private functions
Connect to the FTP site and then perform operations on the FTP site
Verify the FTP application
REFERENCES
SUMMARY
This article describes how to perform the File Transfer Protocol (FTP) operation by using Microsoft Visual Basic .NET. The code samples in this article perform the following FTP commands:
Upload a file to the FTP site
Download a file from the FTP site
Create a folder on the FTP site
Remove a folder from the FTP site
Change a working folder on the FTP site
Remove a file from the FTP site
Rename a file on the FTP site
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Requirements
This article assumes that you are familiar with the following topics:
Programming with Microsoft Visual Basic .NET
FTP commands
The following list outlines the recommended hardware, software, network infrastructure, and service packs that you need:
Microsoft Windows 2000, Microsoft Windows XP, or Microsoft Windows Server 2003
Visual Basic .NET
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Add references, and declare class variables
You can add references and declare class variables to store a remote host name, to store a remote password, and to set the size of the packet that is used to read and to write data to an FTP server.
Review the following code sample. The "Verify the FTP application" section shows you where to put this code sample and how to make this code sample functional. The "Verify the FTP application" section contains the complete code listing for all the code samples in this article.
Imports System
Imports System.Net
Imports System.IO
Imports System.Text
Imports System.Net.Sockets
Public Class clsFTP
#Region "Class Variable Declarations"
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
#End Region
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Define class constructors
You must define the main class constructor with default values. You must define the parameterized constructor that accepts values when the constructor is called.
Review the following code sample. The "Verify the FTP application" section shows you where to put this code sample and how to make this code sample functional. The "Verify the FTP application" section contains the complete code listing for all the code samples in this article.
#Region "Class Constructors"
' 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
#End Region
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Set public properties
You must Set or Get the remote FTP server, the remote port, the remote path, the remote password, and the remote user.
Review the following code sample. The "Verify the FTP application" section shows you where to put this code sample and how to make this code sample functional. The "Verify the FTP application" section contains the complete code listing for all the code samples in this article.
#Region "Public Properties"
'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
#End Region
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Use the public sub-procedures and the public functions
The public functions and the public procedures give details about file upload, file download, folder creation, folder removal, change folder, file removal, file rename, set remote username, and set remote password.
Review the following code sample. The "Verify the FTP application" section shows you where to put this code sample and how to make this code sample functional. The "Verify the FTP application" section contains the complete code listing for all the code samples in this article.
#Region "Public Subs and Functions"
'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,
SendCommand("NLST " & sMask)
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
#End Region
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Use the private sub-procedures and the private functions
The following private sub-procedures and private functions are used to read a reply from the FTP server, to send a command to the FTP server that you are connected to, and to create data.
Review the following code sample. The "Verify the FTP application" section shows you where to put this code sample and how to make this code sample functional. The "Verify the FTP application" section contains the complete code listing for all the code samples in this article.
#Region "Private Subs and Functions"
' 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 Region
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Connect to the FTP site and then perform operations on the FTP site
You can connect to the FTP server and then perform operations such as create a folder, change the current working folder, upload a file, download a file, and rename a file.
The following information applies to the following code sample.
The Example1.txt file, the Example2.doc file, and the Example3.doc file are files that exist on your local hard disk. You start your FTP client program from your local hard disk. These files must be put in the C:\Test location. Test is a placeholder for a folder on your local hard disk.
The MyFolder folder and the MyOwnFolder folder are folders that exist on your FTP server.
The MyOwnFolder folder is a subfolder in the MyFolder folder.
The MyFolder folder is the folder that your FTP site is mapped to.
The value of StrIP is the Internet Protocol (IP) address of your FTP server.
Review the following code sample. The "Verify the FTP application" section shows you where to put this code sample and how to make this code sample functional. The "Verify the FTP application" section contains the complete code listing for all the code samples in this article.
Sub TestFTP()
'Create an instance of the FTP class that is created.
Dim ff As clsFTP
Try
'Pass values to the constructor. These values can be overridden by setting
'the appropriate properties on the instance of the clsFTP class.
'The third parameter is the user name. The FTP site is accessed with the user name.
'If there is no specific user name, the user name can be anonymous.
'The fourth parameter is the password. The FTP server is accessed with the password.
'The fifth parameter is the port of the FTP server. The port of the FTP server is typically 21.
ff = New clsFTP(StrIP, _
"/Myfolder/", _
"anonymous", _
"", _
21)
'Try to log on to the FTP server.
If (ff.Login() = True) Then
'Change the directory on your FTP site.
If (ff.ChangeDirectory("MyOwnFolder") = True) Then
'Successful changing the directory
Console.WriteLine("Changed the directory to the directory that was specified" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful changing the directory
Console.WriteLine("Unable to change to the directory that was specified" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
'Create a directory on your FTP site under the previous directory.
If (ff.CreateDirectory("FTPFOLDERNEW") = True) Then
'Successful creating the directory
Console.WriteLine("A new folder has been created" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful creating the directory
Console.WriteLine("A new folder has not been created" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
'Change the directory on your FTP site under the directory that is specified.
If (ff.ChangeDirectory("FTPFOLDERNEW") = True) Then
'Successful changing the directory
Console.WriteLine("Changed the directory to the directory that was specified" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful changing the directory
Console.WriteLine("Unable to change the directory that was specified" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
ff.SetBinaryMode(True)
'Upload a file from your local hard disk to the FTP site.
ff.UploadFile("C:\Test\Example1.txt")
ff.UploadFile("C:\Test\Example2.doc")
ff.UploadFile("C:\Test\Example3.doc")
'Download a file from the FTP site to your local hard disk.
ff.DownloadFile("Example2.doc", "C:\Test\Example2.doc")
' Remove a file from the FTP site.
If (ff.DeleteFile("Example1.txt") = True) Then
'Successful removing the file on the FTP site
Console.WriteLine("File has been removed from the FTP site" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful removing the file on the FTP site
Console.WriteLine("Unable to remove the file on the FTP site" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
'Rename a file on the FTP site.
If (ff.RenameFile("Example3.doc", "Example3_new.doc")) Then
'Successful renaming the file on the FTP site
Console.WriteLine("File has been renamed" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful renaming the file on the FTP site
Console.WriteLine("File has not been renamed" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
'Change the directory to one directory before.
If (ff.ChangeDirectory("..") = True) Then
'Successful changing the directory
Console.WriteLine("Changed the directory to one directory before" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful changing the directory
Console.WriteLine("Unable to change the directory" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
End If
'Create a new directory.
If (ff.CreateDirectory("MyOwnFolderNew") = True) Then
'Successful creating the directory
Console.WriteLine("A new folder has been created" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful creating the directory
Console.WriteLine("A new folder has not been created" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
'Remove the directory that is created on the FTP site.
If (ff.RemoveDirectory("MyOwnFolderNew")) Then
'Successful removing the directory on the FTP site
Console.WriteLine("Directory has been removed" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful removing the directory on the FTP site
Console.WriteLine("Unable to remove the directory" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
Catch ex As System.Exception
'Display the error message.
Console.WriteLine("Specific Error=" & ex.Message + vbCrLf)
Console.WriteLine("Press 'ENTER' to EXIT")
Console.ReadLine()
Finally
'Always close the connection to make sure that there are not any not-in-use FTP connections.
'Check if you are logged on to the FTP server and then close the connection.
If ff.flag_bool = True Then
ff.CloseConnection()
End If
End Try
End Sub
back to the top
Verify the FTP application
To verify Write permissions to the FTP site and to verify anonymous access to the FTP site, follow these steps:
Click Start, and then click Run.
In the Open box, type inetmgr, and then click OK.
In the Internet Information Services Manager window, expand MyComputer.
MyComputer is the name of your computer.
In the Internet Information Services Manager window, expand FTP sites.
Right-click Default FTP Site, and then click Properties.
In the Default FTP Site Properties dialog box, click to select the Allow anonymous connections check box on the Security Accounts tab.
In the Default FTP Site Properties dialog box, click to select the Write check box on the Home Directory tab. Click OK to close the Default FTP Site Properties dialog box.
To create a console program, follow these steps:
Click Start, point to Programs, point to Microsoft Visual Studio .NET, and then click Microsoft Visual Studio .NET.
On the File menu, point to New, and then click Project.
Under Project Types, click Visual Basic Projects.
Under Templates, click Console Application.
In the Name box, type FTP, and then click OK.
By default, the Module1.vb file is created.
Replace the code in the Module1.vb file with the following code sample:
Imports FTP
Module Module1
Sub TestFTP()
'Create an instance of the FTP class that is created.
Dim ff As clsFTP
Try
'Pass the values to the constructor. These values can be overridden by setting
'the appropriate properties on the instance of the clsFTP class.
ff = New clsFTP(StrIP, _
"/MyFolder/", _
"anonymous", _
"", _
80)
'Try to log on to the FTP server.
If (ff.Login() = True) Then
'Change the directory on your FTP site.
If (ff.ChangeDirectory("MyOwnFolder") = True) Then
'Successful changing the directory
Console.WriteLine("Changed the directory to the directory that was specified" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful changing the directory
Console.WriteLine("Unable to change to the directory that was specified" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
'Create a directory on your FTP site under the previous directory.
If (ff.CreateDirectory("FTPFOLDERNEW") = True) Then
'Successful creating the directory
Console.WriteLine("A new folder has been created" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful creating the directory
Console.WriteLine("A new folder has not been created" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
'Change the directory on your FTP site under the directory that is specified.
If (ff.ChangeDirectory("FTPFOLDERNEW") = True) Then
'Successful changing the directory
Console.WriteLine("Changed the directory to the directory that was specified" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful changing the directory
Console.WriteLine("Unable to change the directory that was specified" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
ff.SetBinaryMode(True)
'Upload a file from your local hard disk to the FTP site.
ff.UploadFile("C:\Test\Example1.txt")
ff.UploadFile("C:\Test\Example2.doc")
ff.UploadFile("C:\Test\Example3.doc")
'Download a file from the FTP site to your local hard disk.
ff.DownloadFile("Example2.doc", "C:\Test\Example4.doc")
' Remove a file from the FTP site.
If (ff.DeleteFile("Example1.txt") = True) Then
'Successful removing the file from the FTP site
Console.WriteLine("File has been removed from the FTP site" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful removing the file from the FTP site
Console.WriteLine("Unable to remove file from the FTP site" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
'Rename a file on the FTP site.
If (ff.RenameFile("Example3.doc", "Example3_new.doc")) Then
'Successful renaming the file on the FTP site
Console.WriteLine("File has been renamed" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful renaming the file on the FTP site
Console.WriteLine("File has not been renamed" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
'Change the directory to one directory before.
If (ff.ChangeDirectory("..") = True) Then
'Successful changing the directory
Console.WriteLine("Changed the directory to one directory before" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful changing the directory
Console.WriteLine("Unable to change the directory" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
End If
'Create a new directory.
If (ff.CreateDirectory("MyOwnNewFolder") = True) Then
'Successful creating the directory
Console.WriteLine("A new folder has been created" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful creating the directory
Console.WriteLine("A new folder has not been created" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
'Remove the directory that was created on the FTP site.
If (ff.RemoveDirectory("MyOwnNewFolder")) Then
'Successful removing the directory on the FTP site
Console.WriteLine("Directory has been removed" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
Else
'Unsuccessful removing the directory on the FTP site.
Console.WriteLine("Unable to remove the directory" + vbCrLf)
Console.WriteLine("Press 'ENTER'")
Console.ReadLine()
End If
Catch ex As System.Exception
'Display the error message.
Console.WriteLine("Specific Error= " & ex.Message + vbCrLf)
Console.WriteLine("Press 'ENTER' to Exit")
Console.ReadLine()
Finally
'Always close the connection to make sure that there are not any not-in-use FTP connections.
'Check to see if you are logged on to the FTP server and then close the connection.
If ff.flag_bool = True Then
ff.CloseConnection()
End If
End Try
End Sub
Sub Main()
'Call the procedure from the main.
TestFTP()
End Sub
End Module
To add a Class file to the project, follow these steps:
In Microsoft Solution Explorer, right-click the FTP project, point to Add, and then click Add New Item.
Under Templates, click Class.
In the Name box, type clsFTP.vb, and then click OK.
Replace the code in the clsFTP.vb file with the following code sample:
' This class permits you to perform direct connections to FTP sites in Visual Basic. NET.
' The class supports the following FTP commands:
' - Upload a file
' - Download a file
' - Create a directory
' - Remove a directory
' - Change directory
' - Remove a file
' - Rename a file
' - Set the user name of the remote user
' - Set the password of the remote user
Imports System
Imports System.Net
Imports System.IO
Imports System.Text
Imports System.Net.Sockets
'FTP Class
Public Class clsFTP
#Region "Class Variable Declarations"
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
#End Region
#Region "Class Constructors"
' 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
#End Region
#Region "Public Properties"
'Set or Get the name of the FTP server that you want to connect to.
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 to.
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 to.
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 the remote password of the FTP server that you want to connect to.
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 to.
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
#End Region
#Region "Public Subs and Functions"
'Return a list of files from the file system. Return these files in a string() array.
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 to see if you are logged on to the FTP server.
If (Not (m_bLoggedIn)) Then
Login()
End If
cSocket = CreateDataSocket()
'Send an FTP command.
SendCommand("NLST " & sMask)
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 the 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 directory 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 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 an 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 directory of the assembly. Keep the same file name.
Public Sub DownloadFile(ByVal sFileName As String)
DownloadFile(sFileName, "", False)
End Sub
' Download a remote file to the local directory of the Assembly. 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. You must include a path. 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 from 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 new 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 directory 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 directory 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 directory on the remote FTP server.
Public Function RemoveDirectory(ByVal sDirName As String) As Boolean
Dim bResult As Boolean
bResult = True
'Check if logged on to the FTP server
If (Not (m_bLoggedIn)) Then
Login()
End If
'Send an FTP command to remove directory 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 directory 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 logged on to the FTP server
If (Not (m_bLoggedIn)) Then
Login()
End If
'Send an FTP command to change directory 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
#End Region
#Region "Private Subs and Functions"
' 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 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. 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 Region
End Class
To change the Startup object of your project, follow these steps:
On the Project menu, click FTP Properties.
In the FTP Property Pages dialog box, set the value of the Startup object box to Sub Main, and then click OK.
To build your FTP application, follow these steps:
On the Build menu, click Build Solution.
On the Debug menu, click Start to run the application.
Notice on the FTP site that the application creates a directory, uploads a file, downloads a file to your local drive, renames a file, deletes a file, and changes the current directory.
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REFERENCES
For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
812404 HOW TO: Write pluggable protocol to support FTP in managed classes by using Visual Basic .NET
For additional information about supported FTP commands, visit the following Microsoft Developer Network (MSDN) Web site:
http://msdn.microsoft.com/library/en-us/wceftpsv/html/ceconSupportedFTPCommands.asp
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Keywords: kbProgramming kbClient kbFTP kbHOWTOmaster KB832679
Technology: kbAudDeveloper kbVBNET2002 kbVBNET2003 kbVBNETSearch kbVBSearch
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Thursday, October 16, 2008
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