NAME

Net::Frame::Dump::Online - tcpdump like implementation, online mode

SYNOPSIS

use Net::Frame::Dump::Online;

#
# Simply create a Dump object
#
my $oDump = Net::Frame::Dump::Online->new(
   dev => 'eth0',
);

$oDump->start;

# Gather frames
while (1) {
   if (my $f = $oDump->next) {
      my $raw            = $f->{raw};
      my $firstLayerType = $f->{firstLayer};
      my $timestamp      = $f->{timestamp};
   }
}

$oDump->stop;

#
# Create a Dump object, using on-event loop
#
sub callOnRecv {
   my ($h, $data) = @_;
   print "Data: $data\n";
   my $oSimple = Net::Frame::Simple->newFromDump($h);
   print $oSimple->print."\n";
}

my $oDumpEvent = Net::Frame::Dump::Online->new(
   dev         => 'eth0',
   onRecv      => \&callOnRecv,
   onRecvCount => 1,
   onRecvData  => 'test',
);

# Will block here, until $onRecvCount packets read, or a stop() call has 
# been performed.
$oDumpEvent->start;

#
# Default parameters on creation
#
my $oDumpDefault = Net::Frame::Dump::Online->new(
   dev            => undef,
   timeoutOnNext  => 3,
   timeout        => 0,
   promisc        => 0,
   unlinkOnStop   => 1,
   file           => "netframe-tmp-$$.$int.pcap",
   filter         => '',
   overwrite      => 0,
   isRunning      => 0,
   keepTimestamp  => 0,
   onRecvCount    => -1,
   frames         => [],
);

DESCRIPTION

This module implements a tcpdump-like program, for live capture from networks.

ATTRIBUTES

dev

The network interface to listen on. No default value.

timeoutOnNext

Each time you call next method, an internal counter is updated. This counter tells you if you have not received any data since timeoutOnNext seconds. When a timeout occurred, timeout is set to true.

timeout

When timeoutOnNext seconds has been reached, this variable is set to true, and never reset. See timeoutReset if you want to reset it.

snaplen

If you want to capture a different snaplen, set it a number. Default to 1514.

promisc

By default, interface is not put into promiscuous mode, set this parameter to true if you want it.

unlinkOnStop

When you call stop method, the generated .pcap file is removed, unless you set this parameter to a false value.

onRecv

If you place a reference to a sub in this attribute, it will be called each time a packet is received on the interface. See SYNOPSIS for an example usage.

onRecvData

This parameter will store additional data to be passed to onRecv callback.

onRecvCount

By default, it is set to read forever packets that reach your network interface. Set it to a positive value to read only onRecvCount frames.

The following are inherited attributes:

file

Name of the generated .pcap file. See SYNOPSIS for the default name.

filter

Pcap filter to use. Default to no filter.

overwrite

Overwrites a .pcap file that already exists. Default to not.

firstLayer

Stores information about the first layer type contained on read frame. This attribute is filled only after a call to start method.

isRunning

Returns true if a call to start has been done, false otherwise or if a call to stop has been done.

keepTimestamp

Sometimes, when frames are captured and saved to a .pcap file, timestamps sucks. That is, you send a frame, and receive the reply, but your request appear to have been sent after the reply. So, to correct that, you can use Net::Frame::Dump own timestamping system. The default is 0. Set it manually to 1 if you need original .pcap frames timestamps.

METHODS

new

new (hash)

Object constructor. You can pass attributes that will overwrite default ones. See SYNOPSIS for default values.

start

When you want to start reading frames from network, call this method.

stop

When you want to stop reading frames from network, call this method.

next

Returns the next captured frame; undef if none awaiting. Each time this method is called, a comparison is done to see if no frame has been captured during timeoutOnNext number of seconds. If so, timeout attribute is set to 1 to reflect the pending timeout.

store (Net::Frame::Simple object)

This method will store internally, sorted, the Net::Frame::Simple object passed as a single parameter. getKey methods, implemented in various Net::Frame::Layer objects will be used to efficiently retrieve (via getKeyReverse method) frames.

Basically, it is used to make recv method (from Net::Frame::Simple) to retrieve quickly the reply frame for a request frame.

getFramesFor (Net::Frame::Simple object)

This will return an array of possible reply frames for the specified Net::Frame::Simple object. For example, reply frames for a UDP probe will be all the frames which have the same source port and destination port as the request.

flush

Will flush stored frames, the one which have been stored via store method.

timeoutReset

Reset the internal timeout state (timeout attribute).

getStats

Tries to get packet statistics on an open descriptor. It returns a reference to a hash that has to following fields: ps_recv, ps_drop, ps_ifdrop.

isFather

isSon

These methods will tell you if your current process is respectively the father, or son process of Net::Frame::Dump::Online object.

SEE ALSO

Net::Frame::Dump

AUTHOR

Patrice <GomoR> Auffret

COPYRIGHT AND LICENSE

Copyright (c) 2006-2020, Patrice <GomoR> Auffret

You may distribute this module under the terms of the Artistic license. See LICENSE.Artistic file in the source distribution archive.