Socket problem

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  • Rob T
    #1

    Socket problem

    I have a very simple little program that connects to our email server to
    send out emails. When I compiled it with .VS2003 (net 1.1), it works fine.
    with VS2005 (.net 2.0), it hangs on the last ReadInfo

    Any suggestions? thanks!

    Public Function send2() As String
    Dim err As String = ""

    soc = ConnectSocket(S erver, 25)
    Debug.Write(Rea dInfo(err) & vbCrLf)
    WriteInfo("HELO ", Err)
    Debug.Write(Rea dInfo(err) & vbCrLf)

    WriteInfo("MAIL FROM:" & From, err)
    Debug.Write(Rea dInfo(err) & vbCrLf)

    WriteInfo("RCPT TO:" & "RTorcellini@my domain.com", err)
    Debug.Write(Rea dInfo(err) & vbCrLf)

    WriteInfo("DATA ", err)
    Debug.Write(Rea dInfo(err) & vbCrLf)

    WriteInfo("This is a test" & vbCrLf & "." & vbCrLf, err)
    Debug.Write(Rea dInfo(err) & vbCrLf)

    WriteInfo("QUIT ", err)
    Debug.Write(Rea dInfo(err) & vbCrLf) 'CODE HANGS HERE- SEE BELOW
    soc.Close()
    End Function

    Private Function WriteInfo(ByVal Info As String, ByRef err As String) As
    String
    Dim bytes As Byte()
    Dim ASCII As Encoding = Encoding.ASCII
    bytes = ASCII.GetBytes( Info & vbCrLf)
    soc.Send(bytes, bytes.Length, 0)
    End Function

    Private Function ReadInfo(ByRef Err As String) As String
    Try
    Dim bytes As Int32
    Dim RecvBytes(256) As Byte
    Dim ASCII As Encoding = Encoding.ASCII
    bytes = soc.Receive(Rec vBytes, RecvBytes.Lengt h, 0) 'HANGS HERE
    ON LAST ReadInfo
    Return ASCII.GetString (RecvBytes, 0, bytes)
    Catch ex As Exception
    Err = ex.Message
    End Try
    End Function


    Tags: None
    • Peter Duniho
      #2
      Re: Socket problem

      On Thu, 22 Mar 2007 09:15:10 -0700, Rob T
      <RTorcellini@DO NTwalchemSPAM.c omwrote:
      I have a very simple little program that connects to our email server to
      send out emails. When I compiled it with .VS2003 (net 1.1), it works
      fine.
      with VS2005 (.net 2.0), it hangs on the last ReadInfo
      Your code displays the classic beginner bug of assuming that a single
      receive will actually receive every byte that was sent. That's not true.
      The Receive method can return anywhere between 1 and the total numebr of
      bytes sent. It is your responsibility to keep receiving bytes until
      you've gotten as many as you expect or need.

      I would be surprised if changing the compiler is actually what changed the
      behavior...but regardless, I suspect that if you fix the code so that in
      ReadInfo, you loop until you've read as many bytes as you really want, it
      will work fine. In the specific example, it appears that you want to
      receive until you've gotten the cr/lf terminator for each line of data.
      For different situations, you will use different criteria.

      Pete

        Comment

        • Rob T
          #3
          Re: Socket problem

          As a followup to this. There is nothing wrong with the code. Our IT dept
          had deployed a new version of Symantec Antivirus and it had the SMTP client
          installed....bl ocks just about everything! Once I disabled it....let the
          good times roll!


          "Peter Duniho" <NpOeStPeAdM@nn owslpianmk.comw rote in message
          news:op.tpln92h u8jd0ej@petes-computer.local. ..
          On Thu, 22 Mar 2007 09:15:10 -0700, Rob T
          <RTorcellini@DO NTwalchemSPAM.c omwrote:
          >
          >I have a very simple little program that connects to our email server to
          >send out emails. When I compiled it with .VS2003 (net 1.1), it works
          >fine.
          >with VS2005 (.net 2.0), it hangs on the last ReadInfo
          >
          Your code displays the classic beginner bug of assuming that a single
          receive will actually receive every byte that was sent. That's not true.
          The Receive method can return anywhere between 1 and the total numebr of
          bytes sent. It is your responsibility to keep receiving bytes until
          you've gotten as many as you expect or need.
          >
          I would be surprised if changing the compiler is actually what changed the
          behavior...but regardless, I suspect that if you fix the code so that in
          ReadInfo, you loop until you've read as many bytes as you really want, it
          will work fine. In the specific example, it appears that you want to
          receive until you've gotten the cr/lf terminator for each line of data.
          For different situations, you will use different criteria.
          >
          Pete

            Comment

            • Peter Duniho
              #4
              Re: Socket problem

              On Fri, 23 Mar 2007 07:26:19 -0700, Rob T
              <RTorcellini@DO NTwalchemSPAM.c omwrote:
              As a followup to this. There is nothing wrong with the code.
              Well, your code still has the bug I describe. So it's not actually true
              that "there is nothing wrong with the code". It may work fine now, but it
              is likely to break some time in the future.

                Comment

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