Networkstream Class and POP3 Protocol Problem

[Darcy Ryan]

Greetings,

I am having a problem trying to use the TcpClient and
NetworkStream classes to connect to a POP3 server. My
(simplified test) VB.NET code is as follows:

Dim tcpclient As New TcpClient
tcpclient.Conne ct("<server name>", 110)

Dim ns As NetworkStream = tcpclient.GetSt ream

Dim Rxbytes(tcpclie nt.ReceiveBuffe rSize) As Byte
ns.Read(Rxbytes , 0, CInt(tcpclient. ReceiveBufferSi ze))

Dim Txbytes As Byte() = Encoding.ASCII. GetBytes("USER
<name>\r\n")

ns.Write(Txbyte s, 0, Txbytes.Length)

ns.Read(Rxbytes , 0, CInt(tcpclient. ReceiveBufferSi ze))

...

The code above will connect to the POP3 server and read
the "+OK ..." response for an active connection. The write
command executes ok, but the program hangs on the Read
command (as if the server has not recieved a valid USER
command). I have added a check for ns.DataAvailabl e prior
to the read, which returns no data available. I think that
I am missing something obvious in writing the USER command
(possibly with the CRLF).

I have verified my command strings by connecting to my
server using telnet, I have checked the samples on MSDN
and Google, and I am now into the 'banging head on
keyboard' stage.

Any advice?

Thanks,
Darcy

[A]

Re: Networkstream Class and POP3 Protocol Problem

> I have verified my command strings by connecting to my[color=blue]
> server using telnet, I have checked the samples on MSDN
> and Google, and I am now into the 'banging head on
> keyboard' stage.
>
> Any advice?[/color]

Perhaps you need to send a NULL terminated string? "\0" I know that
sometimes that is what is expected. Just a guess.

-akshay

[Darcy Ryan]

Re: Networkstream Class and POP3 Protocol Problem

I tried that both after and in place of the CRLF (\r\n)
characters (spec'd by the POP3 protocol) with no luck.
Thanks for the suggestion though, Akshay, I hadn't thought
of that.

Darcy
[color=blue]
>
>Perhaps you need to send a NULL terminated string? "\0" I[/color]
know that[color=blue]
>sometimes that is what is expected. Just a guess.
>
>-akshay
>
>
>.
>[/color]

[Stephen Martin]

Re: Networkstream Class and POP3 Protocol Problem

VB does not use escape sequences such as '\r\n'. Try:

Dim Txbytes As Byte() = Encoding.ASCII. GetBytes("USER <name>" &
Environment.New Line)

"Darcy Ryan" <darcyryan@hotm ail.com> wrote in message
news:005c01c34d 54$c39db4b0$a50 1280a@phx.gbl.. .[color=blue]
> Greetings,
>
> I am having a problem trying to use the TcpClient and
> NetworkStream classes to connect to a POP3 server. My
> (simplified test) VB.NET code is as follows:
>
> Dim tcpclient As New TcpClient
> tcpclient.Conne ct("<server name>", 110)
>
> Dim ns As NetworkStream = tcpclient.GetSt ream
>
> Dim Rxbytes(tcpclie nt.ReceiveBuffe rSize) As Byte
> ns.Read(Rxbytes , 0, CInt(tcpclient. ReceiveBufferSi ze))
>
> Dim Txbytes As Byte() = Encoding.ASCII. GetBytes("USER
> <name>\r\n")
>
> ns.Write(Txbyte s, 0, Txbytes.Length)
>
> ns.Read(Rxbytes , 0, CInt(tcpclient. ReceiveBufferSi ze))
>
> ...
>
> The code above will connect to the POP3 server and read
> the "+OK ..." response for an active connection. The write
> command executes ok, but the program hangs on the Read
> command (as if the server has not recieved a valid USER
> command). I have added a check for ns.DataAvailabl e prior
> to the read, which returns no data available. I think that
> I am missing something obvious in writing the USER command
> (possibly with the CRLF).
>
> I have verified my command strings by connecting to my
> server using telnet, I have checked the samples on MSDN
> and Google, and I am now into the 'banging head on
> keyboard' stage.
>
> Any advice?
>
> Thanks,
> Darcy[/color]