FTP dam FTP

[a_jam_sandwich]

Currently im trying to write an FTP class but have run into problems. The below code connects to the server and gets the welcome message after that nothing yarda :confused: so I have no idea

 

see code below.

 

Imports System.Net
Imports System.Net.Sockets
Imports System.Text.Encoding

Module ModFTPClass

   Public Class classMyFTP

       Private _username As String = "anonymous"
       Private _password As String = ""
       Private _ip As String = ""
       Private _ISCONNECTED As Boolean = False

       Private FTP_Socket As New TcpClient
       Private FTP_networkStream As NetworkStream


       Public Event onError(ByVal ErrorMessage As String)

       Public Function Connect() As Boolean
           If OpenConnection() Then
               ReceiveCommand()
               SendCommand("USER " & _username)
               ReceiveCommand()
               SendCommand("PASS " & _password)
               ReceiveCommand()
               SendCommand("LS www")
               ReceiveCommand()
           End If
       End Function

       Private Function OpenConnection() As Boolean
           Try
               FTP_Socket.Connect("ftp.microsoft.com", 21)
               FTP_networkStream = FTP_Socket.GetStream()
               _ISCONNECTED = True
               Return True
           Catch ex As Exception
               RaiseEvent onError(ex.Message.ToString)
               Return False
           End Try
       End Function

       Private Function SendCommand(ByVal UserCommand As String)
           If _ISCONNECTED Then
               Dim MyCommand As Byte() = ASCII.GetBytes(UserCommand & vbCrLf)
               FTP_networkStream.Write(MyCommand, 0, MyCommand.Length)
           End If
       End Function

       Private Function ReceiveCommand() As String
           If _ISCONNECTED Then
               If FTP_networkStream.CanRead Then
                   Dim MyCommand(1024) As Byte
                   Dim BytesRead As Integer = 1
                   Dim ReceivedCommand As String
                   Dim Starttime As Long = Environment.TickCount
                   Do
                       BytesRead = FTP_networkStream.Read(MyCommand, 0, 1024)
                       Console.WriteLine(BytesRead)
                       ReceivedCommand += ASCII.GetChars(MyCommand)
                   Loop While FTP_networkStream.DataAvailable
                   Console.WriteLine(ReceivedCommand)
               End If
           End If
       End Function

   End Class

End Module

 

If anyone can figuar this out that would be great

 

Cheers

 

Andy

[PlausiblyDamp]

Just stepping through your code and the FTP server returns a "command not understood" error after you issue "SendCommand("LS www")" - is that the problem you mean?

[a_jam_sandwich]

Not at all i know that will send that response the problem is the response is not being received

[PlausiblyDamp]

Not being received where? When I step through your code I can see the response being written to the ReceivedCommand variable

[a_jam_sandwich]

Strange ??? not what i get. I changed it to use a socket instead and now it seams to work will post source soon

[a_jam_sandwich]

Now i have this

 

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

Module ModFTP

   Public Class classFTP

       Public LogWindow As TextBox

       Private MyFTPSocket As New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)

       Public Function Connect()
           ConnectToHost()
           Response()
           Send("USER Anonymous")
           Response()
           Send("PASS [email]andrew_duff@btinternet.com[/email]")
           Response()
           Response()
           ListDirectory("")
       End Function

       Public Function RunCommand(ByVal Command As String)
           Send(Command)
           Response()
       End Function

       Private Function ConnectToHost()
           Dim MyHost As IPHostEntry = Dns.GetHostByName("ftp.microsoft.com")
           Dim MyEntry As New IPEndPoint(MyHost.AddressList(0), 21)
           MyFTPSocket.Connect(MyEntry)
           If Not LogWindow Is Nothing Then LogWindow.Text += "Connected to [" & MyHost.AddressList(0).ToString & "]" & vbCrLf
       End Function

       Public Function Send(ByVal Command As String)
           Try
               Dim SendBuffer As Byte() = ASCII.GetBytes(Command & Chr(13) & Chr(10))
               MyFTPSocket.Send(SendBuffer, SendBuffer.Length, 0)
               Console.WriteLine("Command Sent")
           Catch ex As Exception
           End Try
       End Function

       Public Function Response()
           Try
               Dim ReceiveBuffer(8000) As Byte
               Dim BytesReceived As Integer = MyFTPSocket.Receive(ReceiveBuffer)
               Console.WriteLine(BytesReceived)
               If Not LogWindow Is Nothing Then LogWindow.Text += ASCII.GetString(ReceiveBuffer, 0, BytesReceived)
           Catch ex As Exception
           End Try
       End Function

       Public Function ListDirectory(ByVal Directory As String)
           Try
               Dim BytesReceived As Integer
               Dim ReponseServerString As String
               Dim ReceiveBuffer(512) As Byte

               RunCommand("LIST")

               'Do
               '    BytesReceived = MyFTPSocket.Receive(ReceiveBuffer, 512, SocketFlags.Peek)
               '    ReponseServerString += Encoding.ASCII.GetString(ReceiveBuffer, 0, BytesReceived)
               'Loop Until BytesReceived = 0

               'If Not LogWindow Is Nothing Then LogWindow.Text += ReponseServerString

           Catch ex As Exception
           End Try
       End Function

   End Class

End Module

 

Problem is the directory listing falls over and dies

 

any ideas

 

thanks

 

andy

[PlausiblyDamp]

Problem seems to be the bit

Do
   BytesReceived = MyFTPSocket.Receive(ReceiveBuffer, 512, SocketFlags.Peek)
   ReponseServerString += Encoding.ASCII.GetString(ReceiveBuffer, 0, BytesReceived)
Loop Until BytesReceived = 0

 

I'm geting a result of "425 Can't open data connection" - however it can take ages to return this response.

It will go into a dead loop here as you are only peeking at the response and not removing it from the buffer.

Will see if I can find anything that could work here.

[a_jam_sandwich]

cheers I used the peek flag to see if anything was in the socket buffer there isn't I tried doing the same commands in telnet when connecting to the server and the same happens on telnet it doesn't return anything.

 

Im thinking maybe I just need to understand the FTP protocol

 

Andy

[a_jam_sandwich]

I've setup an async receive now following code ...

 

       Public Function Response() As String
           Try
               Dim State As New classBuffer(512, MyFTPSocket)
               Dim ReceiveResult As IAsyncResult = MyFTPSocket.BeginReceive(State.Buffer, 0, State.BufferSize, 0, AddressOf ResponseCallback, State)
               ReceiveResult.AsyncWaitHandle.WaitOne(1, True)
               Return State.Response
           Catch ex As Exception
               Console.WriteLine(ex.ToString)
           End Try
       End Function

       Public Sub ResponseCallback(ByVal ar As IAsyncResult)
           Try
               Dim state As classBuffer = CType(ar.AsyncState, classBuffer)
               Dim Socket As Socket = state.Socket
               Dim BytesRead As Integer = Socket.EndReceive(ar)
               If BytesRead > 0 Then
                   Console.WriteLine("-->" & Encoding.ASCII.GetString(state.Buffer, 0, BytesRead))
                   'state.Response += Encoding.ASCII.GetString(state.Buffer, 0, BytesRead)
                   Socket.BeginReceive(state.Buffer, 0, state.BufferSize, 0, AddressOf ResponseCallback, state)
               Else
                   receiveDone.Set()
               End If
           Catch ex As Exception
               Console.WriteLine(ex.ToString)
           End Try
       End Sub

 

The problem is

 

               ReceiveResult.AsyncWaitHandle.WaitOne(1, True)

 

If I do not put a timeout on the thread it hangs forever probley because of this line

 

               Dim BytesRead As Integer = Socket.EndReceive(ar)

 

Checking the help it says the above cause a stop indefinatly until data is received. It seams to me to be bad practice to rely on a timeout to stop the program from hanging?

 

Has anyone got any ideas?

 

Many thanks

 

Andy

 

P.s. Cheer so far PlausiblyDamp your comments are very usful

[a_jam_sandwich]

Blooming hell this is a nightmare which is now comming together didn't think async was so bad lol will post control and source when done.

 

BTW this is my first attemp at tcp using sockets so coding might be a bit weird

 

Andy

[a_jam_sandwich]

Right this is what I have come up with so far it connects in pasv mode

 

* Can display directory listing.

 

* Can change directory

 

* Can download files

 

There are problem with phasing the directory listings on Unix but windows server seems ok there is timeouts for every response

 

Have a look, it is still well in the alpha stage so don't exspect miricals but there is a demo proj file.

 

Any one want to add to it to build it up be my guest

 

Andy

ftp.zip