Net::Packet::IPv4

Section: User Contributed Perl Documentation (3pm)
Updated: 2009-11-09
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NAME

Net::Packet::IPv4 - Internet Protocol v4 layer 3 object

SYNOPSIS

   use Net::Packet::Consts qw(:ipv4);
   require Net::Packet::IPv4;

   # Build a layer
   my $ip = Net::Packet::IPv4->new(
      flags => NP_IPv4_DONT_FRAGMENT,
      dst   => "192.168.0.1",
   );
   $layer->pack;

   print 'RAW: '.unpack('H*', $layer->raw)."\n";

   # Read a raw layer
   my $layer = Net::Packet::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::Packet::Layer and Net::Packet::Layer3 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::Packet::VLAN 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).

METHODS

new

Object constructor. You can pass attributes that will overwrite default ones. Default values:

version: 4

tos: 0

id: getRandom16bitsInt()

length: NP_IPv4_HDR_LEN

hlen: 5

flags: 0

offset: 0

ttl: 128

protocol: NP_IPv4_PROTOCOL_TCP

checksum: 0

src: $Env->ip

dst: ``127.0.0.1''

options: ""

noFixLen: 0

pack

Packs all attributes into a raw format, in order to inject to network. Returns 1
on success, undef otherwise.

unpack

Unpacks raw data from network and stores attributes into the object. Returns 1 on success, undef otherwise.

getHeaderLength

Returns the header length in bytes, not including IP options.

getPayloadLength

Returns the length in bytes of encapsulated layers (that is, layer 4 + layer 7).

getOptionsLength

Returns the length in bytes of IP options.

haveFlagDf

haveFlagMf

haveFlagRf

Returns 1 if the specified flag is set in flags attribute, 0 otherwise.

isProtocolTcp

isProtocolUdp

isProtocolIpv6

isProtocolOspf

isProtocolIgmpv4

isProtocolIcmpv4

Returns 1 if the specified protocol is used at layer 4, 0 otherwise.

CONSTANTS

Load them: use Net::Packet::Consts qw(:ipv4);

NP_IPv4_PROTOCOL_TCP
NP_IPv4_PROTOCOL_UDP
NP_IPv4_PROTOCOL_ICMPv4
NP_IPv4_PROTOCOL_IPv6
NP_IPv4_PROTOCOL_OSPF
NP_IPv4_PROTOCOL_IGMPv4: Various protocol type constants.
NP_IPv4_MORE_FRAGMENT
NP_IPv4_DONT_FRAGMENT
NP_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.

RELATED MODULES

NetPacket, Net::RawIP, Net::RawSock

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