From: TJ <tj+usenet@...13.fr>
Date: 2008-10-28T02:34:41+09:00
Subject: problem catching nested exception

Hello,

  I'm new to ruby and just wrote a script that try to send many email,
reading them from a database. For each domain, the script opens a TCP
socket to the first available MX, and try to send as many email as it
can.

  My problem is that my script does not always catch exception as I
want, and I think my exception handling in nested loops is not correct.
Here is a code extract, starting with a SMTP connection :

      begin
        Timeout.timeout 1 do
          smtp = Net::SMTP.start mx, 25, $hostname
        end
      rescue Exception => e
        case e
          when Timeout::Error
            error = 'timeout connect'
          when Errno::ECONNREFUSED
            error = 'connection refused'
          when Errno::ECONNRESET
            error = 'connection reset'
          when Errno::EHOSTUNREACH
            error = 'host not reachable'
          else
            error = "unknown #{e.to_s}"
        end
        puts "      KO #{error}, next MX" if $verbose
        next
      end

      domain.addr.each do |addr|
        puts "      #{addr.email} (#{addr.id})" if $verbose

        begin
          Timeout.timeout 1 do
            smtp.send_message data, mailing.return_path, addr.email
          end
        rescue Exception => ee
          case ee
            when Net::SMTPServerBusy, Net::SMTPSyntaxError, Net::SMTPFatalError, Net::SMTPUnknownError
              error = ee.to_s.strip
            when Timeout::Error
              error = '001 timeout send'
            when EOFError
              error = '002 eof'
            when Errno::ECONNRESET
              error = '004 connection reset'
            when TypeError
              error = '090 strange TypeError'
            else
              error = "unknown #{ee.to_s}"
          end
          puts "        KO #{error}" if $verbose
          next
        end

        puts "        OK" if $verbose
      end

      smtp.finish
      break

  "Most of the time" it works, but sometimes my script failed that
way :

      email@address (693792)
        KO 451 This server employs greylisting as a means of reducing
spam. Please resend e-mail shortly.
/usr/lib/ruby/1.8/net/protocol.rb:133:in `sysread': Connection reset by
peer (Errno::ECONNRESET)
    from /usr/lib/ruby/1.8/net/protocol.rb:133:in `rbuf_fill'
    from /usr/lib/ruby/1.8/timeout.rb:56:in `timeout'
    from /usr/lib/ruby/1.8/timeout.rb:76:in `timeout'
    from /usr/lib/ruby/1.8/net/protocol.rb:132:in `rbuf_fill'
    from /usr/lib/ruby/1.8/net/protocol.rb:116:in `readuntil'
    from /usr/lib/ruby/1.8/net/protocol.rb:126:in `readline'
    from /usr/lib/ruby/1.8/net/smtp.rb:664:in `recv_response'
    from /usr/lib/ruby/1.8/net/smtp.rb:651:in `getok'
     ... 8 levels...
    from /root/bin/mailing_3.rb:195:in `each'
    from /root/bin/mailing_3.rb:195
    from /root/bin/mailing_3.rb:193:in `each'
    from /root/bin/mailing_3.rb:193

  I do not understand why Errno::ECONNRESET is not catch, because I use
it in each rescue block, and I do not see why it would be thrown in
another part of the script. I also do not understand why "sometimes" it
work as I want and "sometimes" not.

  I removed some part of the script in this post because of its length,
full script is available at :

http://pastie.org/301549

  Any comment will be greatly welcomed, not only for my exception
problem, but I really need to understand that last one ;-)