NAME

Net::Frame::Layer::IPv4 - Internet Protocol v4 layer object

SYNOPSIS

   use Net::Frame::Layer::IPv4 qw(:consts);
   # Build a layer
   my $layer = Net::Frame::Layer::IPv4->new(
      version  => 4,
      tos      => 0,
      id       => getRandom16bitsInt(),
      length   => NF_IPv4_HDR_LEN,
      hlen     => 5,
      flags    => 0,
      offset   => 0,
      ttl      => 128,
      protocol => NF_IPv4_PROTOCOL_TCP,
      checksum => 0,
      src      => '127.0.0.1',
      dst      => '127.0.0.1',
      options  => '',
      noFixLen => 0,
   );
   $layer->pack;
   print 'RAW: '.$layer->dump."\n";
   # Read a raw layer
   my $layer = Net::Frame::Layer::IPv4->new(raw => $raw);
   print $layer->print."\n";
   print 'PAYLOAD: '.unpack('H*', $layer->payload)."\n"
      if $layer->payload;

DESCRIPTION

This modules implements the encoding and decoding of the IPv4 layer.

RFC: ftp://ftp.rfc-editor.org/in-notes/rfc791.txt

See also Net::Frame::Layer for other attributes and methods.

ATTRIBUTES

id: IP ID of the datagram.
ttl: Time to live.
src
dst: Source and destination IP addresses.
protocol: Of which type the layer 4 is.
checksum: IP checksum.
flags: IP Flags.
offset: IP fragment offset.
version: IP version, here it is 4.
tos: Type of service flag.
length: Total length in bytes of the packet, including IP headers (that is, layer 3 + layer 4 + layer 7).
hlen: Header length in number of words, including IP options.
options: IP options, as a hexadecimal string.
noFixLen: Since the byte ordering of length attribute varies from system to system, a subroutine inside this module detects which byte order to use. Sometimes, like when you build Net::Frame::Layer::8021Q layers, you may have the need to avoid this. So set it to 1 in order to avoid fixing. Default is 0 (that is to fix).

The following are inherited attributes. See Net::Frame::Layer for more information.

raw
payload
nextLayer

METHODS

new
new (hash): Object constructor. You can pass attributes that will overwrite default ones. See SYNOPSIS for default values.
getHeaderLength: Returns the header length in bytes, not including IP options.
getOptionsLength: Returns the length in bytes of IP options. 0 if none.
computeLengths ({ payloadLength => VALUE }): In order to compute lengths attributes within IPv4 header, you need to pass via a hashref the number of bytes contained in IPv4 payload (that is, the sum of all layers after the IPv4 one).
computeChecksums: Computes the IPv4 checksum.

The following are inherited methods. Some of them may be overridden in this layer, and some others may not be meaningful in this layer. See Net::Frame::Layer for more information.

layer
computeLengths
computeChecksums
pack
unpack
encapsulate
getLength
getPayloadLength
print
dump

CONSTANTS

Load them: use Net::Frame::Layer::IPv4 qw(:consts);

NF_IPv4_PROTOCOL_ICMPv4
NF_IPv4_PROTOCOL_IGMP
NF_IPv4_PROTOCOL_IPIP
NF_IPv4_PROTOCOL_TCP
NF_IPv4_PROTOCOL_EGP
NF_IPv4_PROTOCOL_IGRP
NF_IPv4_PROTOCOL_CHAOS
NF_IPv4_PROTOCOL_UDP
NF_IPv4_PROTOCOL_IDP
NF_IPv4_PROTOCOL_DCCP
NF_IPv4_PROTOCOL_IPv6
NF_IPv4_PROTOCOL_IPv6ROUTING
NF_IPv4_PROTOCOL_IPv6FRAGMENT
NF_IPv4_PROTOCOL_IDRP
NF_IPv4_PROTOCOL_RSVP
NF_IPv4_PROTOCOL_GRE
NF_IPv4_PROTOCOL_ESP
NF_IPv4_PROTOCOL_AH
NF_IPv4_PROTOCOL_ICMPv6
NF_IPv4_PROTOCOL_EIGRP
NF_IPv4_PROTOCOL_OSPF
NF_IPv4_PROTOCOL_ETHERIP
NF_IPv4_PROTOCOL_PIM
NF_IPv4_PROTOCOL_VRRP
NF_IPv4_PROTOCOL_STP
NF_IPv4_PROTOCOL_SCTP
NF_IPv4_PROTOCOL_UDPLITE: Various protocol type constants.
NF_IPv4_MORE_FRAGMENT
NF_IPv4_DONT_FRAGMENT
NF_IPv4_RESERVED_FRAGMENT: Various possible flags.

AUTHOR

Patrice <GomoR> Auffret

COPYRIGHT AND LICENSE

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