PayPal IPN and Session variables RSS

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  flipknob

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  PayPal IPN and Session variables

  Jan 22, 2009 03:56 PM|LINK

   Hello,
  
  I am making a website that has a Buy Now button. Once the user confirms the payment to be made, PayPal uses a notification text stream that is sent to my site. If my notification page gets the stream and if hasn't been altered you can make it do things on the db side or whatever. then that stream is sent back to Paypal where the user is then redirected to the completed page.
  
  Here's my trouble; If the response from PayPal is verified, I want to run a little task against the DB to allow the information the user paid for to now be viewable to all visitors. In that, I use a session variable to store the record ID of the data the user entered. But the notification page seems to be completely ignoring my session variables. Everything else works as it should
  
  In the example below, the session variables are being used for testing. I was using them to see where the page was breaking. The values are to be displayed on another page. Also, this page will only send an email with the whole IPN text. I don't have my db code setup on this example.

  Why would the page not assign the text values to the session variables?

  -----------------------------------------------------------------------------------------------------

  Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
          
          Session("test1") = "Page load is good"
   
          'Read in IPN POST 
          Dim strFormValues As String = Encoding.ASCII.GetString(Request.BinaryRead(Request.ContentLength))
           Dim strNewValue
   
          ' Create the request back
          Dim req As HttpWebRequest = CType(WebRequest.Create("https://www.sandbox.paypal.com/cgi-bin/webscr"),  _
          HttpWebRequest)
   
          ' Set values for the request back
          req.Method = "POST"
          req.ContentType = "application/x-www-form-urlencoded"
          strNewValue = strFormValues + "&cmd=_notify-validate"
          req.ContentLength = strNewValue.Length
   
          ' Write the request back IPN strings
          Dim stOut As StreamWriter = New StreamWriter(req.GetRequestStream(), _
          Encoding.ASCII)
          stOut.Write(strNewValue)
          stOut.Close()
   
          'send the request, read the response
          Dim strResponse As HttpWebResponse = CType(req.GetResponse(), HttpWebResponse)
          Dim IPNResponseStream As Stream = strResponse.GetResponseStream
          Dim encode As Encoding = System.Text.Encoding.GetEncoding("utf-8")
          Dim readStream As New StreamReader(IPNResponseStream, encode)
   
          Dim read(256) As [Char]
          ' Reads 256 characters at a time.
   
          Dim count As Integer = readStream.Read(read, 0, 256)
   
          While count > 0
              ' Dumps the 256 characters to a string and displays the string to the console.
              Dim IPNResponse As New [String](read, 0, count)
              count = readStream.Read(read, 0, 256)
   
              ' if IPN response was VERIFIED..perform VERIFIED handling
              'for this example - send email of raw IPN string
   
              If IPNResponse = "VERIFIED" Then
                  Session("test2") = "It hit the verified"
   
                  Dim myEmail As New MailMessage
                  myEmail.To.Add("user@domainname.com")
                  myEmail.From = New MailAddress(String.Format("{0} <{1}>", "domainname.com", "noreply@domainname.com"))
                  myEmail.Body = strNewValue
                  myEmail.Subject = "IPN VERIFIED test"
                  Dim client As New System.Net.Mail.SmtpClient()
                  client.Credentials = New System.Net.NetworkCredential("user@domainname.com", "password")
                  client.Send(myEmail)
   
              Else
   
                  ' if IPN is INVALID
                  'log and manually investigate
   
                  Session("test3") = "It hit the invalid"
   
                  Dim myEmail As New MailMessage
                  myEmail.To.Add("user@domainname.com")
                  myEmail.From = New MailAddress(String.Format("{0} <{1}>", "domainname.com", "noreply@domainname.com"))
                  myEmail.Body = strNewValue
                  myEmail.Subject = "IPN INVALID test"
                  Dim client As New System.Net.Mail.SmtpClient()
                  client.Credentials = New System.Net.NetworkCredential("user@domainname.com", "password")
                  client.Send(myEmail)
              End If
          End While
   
          'tidy up, close streams
          readStream.Close()
          strResponse.Close()
  

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