Re: Continuous packet capture

I'm not sure that POE::Component::Pcap works like the 
POE::Component::Server::TCP.  It appears to be implemented as a separate 
POE::Session and uses select() with an internal file descriptor to poll 
the device for new packets and fire the events specified by the dispath 
argument.

Jonathan S. Polacheck wrote:
> Nosing around in the mailing list archive I find;
> 
> 
> "Re: Prioritizing Event Loops
> 
> Martijn van Beers
> Fri, 18 Jan 2008 11:37:22 -0800
> <snip>
> In POE, all your external data, whether from a socket or a file, or
> something else entirely, enters your app through a POE::Wheel (you might
> not be aware of having one, since it is mostly hidden inside
> POE::Component::Server::TCP). How the wheel gets the data is supposed to be
> abstracted away.
> </snip>"
> 
> So POE::Component::Pcap is a wheel?
> 
> Jon
> 
> __________________
> 
> Brad,
> 
> Great stuff.  Thanks.  I'm going on the assumption that $inst->[1] (line
> 94) is the raw packet, headers and all.  I plan to test by pointing pcap at
> a capture file and comparing output to input.  My next plan is to add a sql
> insert of $hexpacket at line 108.  My goal is to keep up with an incoming
> data stream of 20-30 k-bytes a second.  After the hex data is safely stored
> in the database I can go back and insert whatever fields (layer 3-4, packet
> length, etc) I want.  Then do a gui to extract traces and do other analysis
> from the stored data.   Here is my code;
> 
>   1  use strict;
>   2  use warnings;
>   3
>   4  use Data::Dumper;
>   5  use Carp;
>   6
>   7  #
>   8  # POE Environment
>   9  # use POE qw(
>  10  #      Component::Pcap
>  11  #      Component::Daemon
>  12  # );
>  13
>  14  use POE qw(
>  15   Component::Pcap
>  16  );
>  17
>  18  #
>  19  # PCAP Options
>  20  my %pcap_opts = (
>  21   dev         => 'eth0',
>  22   snaplen           => 1514,
>  23   promisc           => 1,
>  24   timeout           => 100,
>  25  );
>  26
>  27  #------------------------------------------------------------------------#
>  28  # POE Environment Setup
>  29  #------------------------------------------------------------------------#
>  30  #POE::Component::Daemon->spawn( detach => 1, babysit => 600, max_children => 5 );
>  31
>  32  POE::Session->create(
>  33   inline_states     => {
>  34         _start                  => \&start_processor,
>  35         _stop             => \&stop_processor,
>  36         handle_packet           => \&handle_packet,
>  37   },
>  38  );
>  39
>  40  $_[HEAP]->{i} = 0;
>  41
>  42  #------------------------------------------------------------------------#
>  43  # Run the POE Sessions
>  44  #------------------------------------------------------------------------#
>  45  POE::Kernel->run;
>  46
>  47  #------------------------------------------------------------------------#
>  48  exit 0;
>  49  #------------------------------------------------------------------------#
>  50
>  51  #------------------------------------------------------------------------#
>  52  # Start the Processor
>  53  sub start_processor {
>  54   my ($kernel, $heap) = @_[KERNEL, HEAP];
>  55
>  56   $kernel->alias_set('processor');
>  57
>  58   #
>  59   # Start Packet Capturing
>  60   POE::Component::Pcap->spawn(
>  61         Alias       => 'pcap',
>  62         Device            => $pcap_opts{dev},
>  63         Dispatch    => 'handle_packet',
>  64         Session           => 'processor',
>  65   );
>  66   $kernel->post( pcap => open_live => @pcap_opts{qw(dev snaplen promisc timeout)} );
>  67
>  68   $kernel->post( pcap => 'run' );
>  69  }
>  70  #------------------------------------------------------------------------#
>  71
>  72  #------------------------------------------------------------------------#
>  73  # stop the processor
>  74  sub stop_processor {
>  75   my ($kernel,$heap) = @_[KERNEL,HEAP];
>  76
>  77   #
>  78   # Stop pcap
>  79   $kernel->post( 'pcap' => 'shutdown' );
>  80  }
>  81  #------------------------------------------------------------------------#
>  82
>  83  #------------------------------------------------------------------------#
>  84  sub handle_packet {
>  85   my $offset = 0;
>  86   my $linechars = 0;
>  87   my $hexpacket;
>  88
>  89   $_[HEAP]->{i}++;
>  90   print "sub handle_packet called $_[HEAP]->{i} times\n";
>  91   my ($kernel,$heap,$packets) = @_[KERNEL,HEAP,ARG0];
>  92
>  93   foreach my $inst ( @{ $packets } )  {
>  94         foreach my $char (split(//, $inst->[1])) {
>  95               if ( $linechars == 0 ) {
>  96                     $hexpacket .= sprintf( "%04X ", $offset );
>  97               }
>  98               $linechars++;
>  99               $hexpacket .= sprintf( "%02X ", ord($char) );
> 100               if ( $linechars == 16 ) {
> 101                     $hexpacket .= "\n";
> 102                     $linechars = 0;
> 103                     $offset += 16;
> 104               }
> 105         }
> 106         $hexpacket .= "\n\n";
> 107   }
> 108   print $hexpacket;
> 109   undef($hexpacket);
> 110  }
> 111
> 112  #------------------------------------------------------------------------#
> 

-- 
Brad Lhotsky <[email protected]>
NCTS Computer Specialist  -- 410.558.8006
..  WAR IS PEACE,
     FREEDOM IS SLAVERY,
     IGNORANCE IS STRENGTH ..