Server counts LF but delivers CrLf?

Robert_Zenz · #1 (**permalink**) 07-09-2009, 12:01 PM

Hello everyone again.

I was writing my own POP3 client but ran into some problems along the way. I could hunt down one of them by now, which seems to be the key to most of the problems I experienced.

I'm using a TCPClient to connect to the server and a NetworkStream to read and write data. This is working great, except one thing: The LIST command delivers me the size of the mail in bytes...but with Lf counted, though, if I start to download the mail with the RETR command, I receive CrLf?!

I'm using the simple NetworkStream.Read(bytes(), offset, length) Method to read from the network. This method already delivers CrLf...but the server counts Lf and so the size I received is totally messed up.

Code:

'toReceive is an Int32 from the LIST command
'Me.prv_client is the TCPClient
'Me.prv_strm is the NetworkStream from the client

            Dim buffer(Me.prv_client.ReceiveBufferSize - 1) As Byte
            Dim readAll As Integer = 0
            Dim read As Integer = Int32.MaxValue

            Do
                Array.Clear(buffer, 0, buffer.Length)
                read = 0

                Try
                    read = Me.prv_strm.Read(buffer, 0, buffer.Length)
                Catch ex As IOException
                    Me.writeError(ex.Message)
                End Try

                readAll += read

                res.Append(Me.prv_encoding.GetString(buffer, 0, read))
            Loop While readAll < toReceive

Of course, I'd count the Lf along the way and add them to toReceive (which I do right now, working), but that can't be the solution.

Anybody has ever seen something like this?

Thanks in advance,
Bobby

JohnH · #2 (**permalink**) 07-09-2009, 2:36 PM

Why not use a StreamReader and StreamWriter with the NetworkStream? You are reading and sending crlf terminated lines of strings all the way with this protocol, ie ReadLine/WriteLine. Multiline responses simply end with a "." line.

Robert_Zenz · #3 (**permalink**) 07-10-2009, 3:44 AM

Mmmhhh...you're right. I was afraid that there might be false positive with this simple char sequence (CrLf.CrLf), but they must be the last thing I read.

Thanks for your suggestion, I tried it and it's working (of course).

Thank you,
Bobby

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