Provided by: libnet-patricia-perl_1.22-1build2_amd64 
NAME
Net::Patricia - Patricia Trie perl module for fast IP address lookups
SYNOPSIS
use Net::Patricia;
my $pt = new Net::Patricia;
$pt->add_string('127.0.0.0/8', \$user_data);
$pt->match_string('127.0.0.1');
$pt->match_exact_string('127.0.0.0');
$pt->match_integer(2130706433); # 127.0.0.1
$pt->match_exact_integer(2130706432, 8); # 127.0.0.0
$pt->remove_string('127.0.0.0/8');
$pt->climb(sub { print "climbing at node $_[0]\n" });
undef $pt; # automatically destroys the Patricia Trie
# IPv6 support:
$pt = new Net::Patricia AF_INET6;
$pt->add_string('2001:db8::/32');
$pt->add_string('2001:db8:0:dead::/64');
$pt->add_string('2001:db8:0:beef::/64');
$pt->climb(sub { print "climbing at node $_[0]\n" });
print $pt->match_string('2001:db8:0:dead::1'), "\n";
# IPv4-mapped IPv6 addresses:
$pt->add_string('::ffff:0:0/96');
for my $cidr (qw( 192.0.2.0/24 192.0.2.0/25 192.0.2.128/25 )) {
my($ip, $len) = split(m|/|, $cidr);
$pt->add_string("::ffff:$ip/" .
(96+(defined($len)? $len : 32)), $cidr);
}
$pt->climb(sub { print "climbing at node $_[0]\n" });
print $pt->match_string("::ffff:" . "192.0.2.129"), "\n";
DESCRIPTION
This module uses a Patricia Trie data structure to quickly perform IP address prefix
matching for applications such as IP subnet, network or routing table lookups. The data
structure is based on a radix tree using a radix of two, so sometimes you see patricia
implementations called "radix" as well. The term "Trie" is derived from the word
"retrieval" but is pronounced like "try". Patricia stands for "Practical Algorithm to
Retrieve Information Coded as Alphanumeric", and was first suggested for routing table
lookups by Van Jacobsen. Patricia Trie performance characteristics are well-known as it
has been employed for routing table lookups within the BSD kernel since the 4.3 Reno
release.
The BSD radix code is thoroughly described in "TCP/IP Illustrated, Volume 2" by Wright and
Stevens and in the paper ``A Tree-Based Packet Routing Table for Berkeley Unix'' by Keith
Sklower.
METHODS
new - create a new Net::Patricia object
$pt = new Net::Patricia;
This is the class' constructor - it returns a "Net::Patricia" object upon success or
undef on failure. The constructor takes an optional argument (of AF_INET or AF_INET6,
defaulting to the former), and creates a tree with address and mask values of that
type as keys.
The "Net::Patricia" object will be destroyed automatically when there are no longer
any references to it.
add_string
$pt->add_string(key_string[,user_data]);
The first argument, key_string, is a network or subnet specification in canonical
form, e.g. "10.0.0.0/8", where the number after the slash represents the number of
bits in the netmask. If no mask width is specified, the longest possible mask is
assumed, i.e. 32 bits for AF_INET addresses.
The second argument, user_data, is optional. If supplied, it should be a SCALAR value
(which may be a perl reference) specifying the user data that will be stored in the
Patricia Trie node. Subsequently, this value will be returned by the match methods
described below to indicate a successful search. Remember that perl references and
objects are represented as SCALAR values and therefore the user data can be
complicated data objects.
If no second argument is passed, the key_string will be stored as the user data and
therfore will likewise be returned by the match functions.
On success, this method returns the user_data passed as the second argument or
key_string if no user data was specified. It returns undef on failure.
match_string
$pt->match_string(key_string);
This method searches the Patricia Trie to find a matching node, according to normal
subnetting rules for the address and mask specified.
The key_string argument is a network or subnet specification in canonical form, e.g.
"10.0.0.0/8", where the number after the slash represents the number of bits in the
netmask. If no mask width value is specified, the longest mask is assumed, i.e. 32
bits for AF_INET addresses.
If a matching node is found in the Patricia Trie, this method returns the user data
for the node. This method returns undef on failure.
match_exact_string
$pt->match_exact_string(key_string);
This method searches the Patricia Trie to find a matching node. Its semantics are
exactly the same as those described for "match_string" except that the key must match
a node exactly. I.e. it is not sufficient that the address and mask specified merely
falls within the subnet specified by a particular node.
match_integer
$pt->match_integer(integer[,mask_bits]);
This method searches the Patricia Trie to find a matching node, according to normal
subnetting rules for the address and mask specified. Its semantics are similar to
those described for "match_string" except that the key is specified using an integer
(i.e. SCALAR), such as that returned by perl's "unpack" function for values converted
using the "N" (network-ordered long). Note that this argument is not a packed
network-ordered long.
Just to be completely clear, the integer argument should be a value of the sort
produced by this code:
use Socket;
$integer = unpack("N", inet_aton("10.0.0.0"));
match_exact_integer
$pt->match_exact_integer(integer[,mask_bits]);
This method searches the Patricia Trie to find a matching node. Its semantics are
exactly the same as "match_integer" except that the key must match a node exactly.
I.e. it is not sufficient that the address and mask specified merely falls within the
subnet specified by a particular node.
remove_string
$pt->remove_string(key_string);
This method removes the node which exactly matches the the address and mask specified
from the Patricia Trie.
If the matching node is found in the Patricia Trie, it is removed, and this method
returns the user data for the node. This method returns undef on failure.
climb
$pt->climb([CODEREF]);
This method climbs the Patricia Trie, visiting each node as it does so. It performs a
non-recursive, "preorder" traversal.
The CODEREF argument is optional. It is a perl code reference used to specify a user-
defined subroutine to be called when visiting each node. The node's user data will be
passed as the sole argument to that subroutine.
This method returns the number of nodes successfully visited while climbing the Trie.
That is, without a CODEREF argument, it simply counts the number of nodes in the
Patricia Trie.
Note that currently the return value from your CODEREF subroutine is ignored. In the
future the climb method may return the number of times your subroutine returned non-
zero, as it is called once per node. So, if you are currently relying on the climb
return value to accurately report a count of the number of nodes in the Patricia Trie,
it would be prudent to have your subroutine return a non-zero value.
This method is called climb() rather than walk() because climbing trees (and therfore
tries) is a more popular pass-time than walking them.
climb_inorder
$pt->climb_inorder([CODEREF]);
This method climbs the Patricia Trie, visiting each node in order as it does so. That
is, it performs an "inorder" traversal.
The CODEREF argument is optional. It is a perl code reference used to specify a user-
defined subroutine to be called when visiting each node. The node's user data will be
passed as the sole argument to that subroutine.
This method returns the number of nodes successfully visited while climbing the Trie.
That is, without a CODEREF argument, it simply counts the number of nodes in the
Patricia Trie.
Note that currently the return value from your CODEREF subroutine is ignored. In the
future the climb method may return the number of times your subroutine returned non-
zero, as it is called once per node. So, if you are currently relying on the climb
return value to accurately report a count of the number of nodes in the Patricia Trie,
it would be prudent to have your subroutine return a non-zero value.
This method is called climb() rather than walk() because climbing trees (and therfore
tries) is a more popular pass-time than walking them.
Serialization
Net::Patricia trees, unlike many classes with XS-level data, can be frozen and thawed
using Storable.
BUGS
When passing a CODEREF argument to the climb method, the return value from your CODEREF
subroutine is currently ignored. In the future the climb method may return the number of
times your subroutine returned non-zero, as it is called once per node. So, if you are
currently relying on the climb return value to accurately report a count of the number of
nodes in the Patricia Trie, it would be prudent to have your subroutine return a non-zero
value.
AUTHOR
Dave Plonka <plonka@doit.wisc.edu> Philip Prindeville <philipp@redfish-solutions.com>
Anton Berezin <tobez@tobez.org>
Copyright (C) 2000-2005 Dave Plonka. Copyright (C) 2009 Dave Plonka & Philip
Prindeville. This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later version.
This product includes software developed by the University of Michigan, Merit Network,
Inc., and their contributors. See the copyright file in the patricialib sub-directory of
the distribution for details.
patricialib, the C library used by this perl extension, is an extracted version of MRT's
patricia code from radix.[ch], which was worked on by Masaki Hirabaru and Craig Labovitz.
For more info on MRT see:
http://www.mrtd.net/
The MRT patricia code owes some heritage to GateD's radix code, which in turn owes
something to the BSD kernel.
SEE ALSO
perl(1), Socket, Net::Netmask, Text::Trie, Tree::Trie.
Tree::Radix and Net::RoutingTable are modules by Daniel Hagerty <hag@linnaean.org> written
entirely in perl, unlike this module. At the time of this writing, they are works-in-
progress but may be available at:
http://www.linnaean.org/~hag/