File Coverage

blib/lib/Net/IP/Match/Regexp.pm

Criterion	Covered	Total	%
statement	58	58	100.0
branch	36	36	100.0
condition	17	17	100.0
subroutine	13	13	100.0
pod	3	3	100.0
total	127	127	100.0

package Net::IP::Match::Regexp;

use 5.006;
use strict;
use warnings;
use English qw(-no_match_vars);

use base 'Exporter';
our @EXPORT_OK = qw( create_iprange_regexp create_iprange_regexp_depthfirst match_ip );
our $VERSION   = '1.01';

=head1 NAME

Net::IP::Match::Regexp - Efficiently match IP addresses against ranges

=head1 LICENSE

Copyright 2005-2006 Clotho Advanced Media, Inc.,

Copyright 2007-2008 Chris Dolan,

This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.

=head1 SYNOPSIS

    use Net::IP::Match::Regexp qw( create_iprange_regexp match_ip );

    my $regexp = create_iprange_regexp(
       qw( 10.0.0.0/8 87.134.66.128 87.134.87.0/24 145.97.0.0/16 )
    );
    if (match_ip('209.249.163.62', $regexp)) {
       ...
    }

=head1 DESCRIPTION

This module allows you to check an IP address against one or more IP
ranges.  It employs Perl's highly optimized regular expression engine
to do the hard work, so it is very fast.  It is optimized for speed by
doing the match against a regexp which implicitly checks the broadest
IP ranges first.  An advantage is that the regexp can be computed and
stored in advance (in source code, in a database table, etc) and
reused, saving much time if the IP ranges don't change too often.  The
match can optionally report a value (e.g. a network name) instead of
just a boolean, which makes module useful for mapping IP ranges to
names or codes or anything else.

=head1 LIMITATIONS

This module does not yet support IPv6 addresses, although that feature
should not be hard to implement as long as the regexps start with a 4
vs. 6 flag.  Patches welcome.  :-)

This module only accepts IP ranges in C (aka CIDR)
notation.  To work around that limitation, I recommend
Net::CIDR::Lite to conveniently convert collections of IP address
ranges into CIDR format.

This module makes no effort to validate the IP addresses or ranges
passed as arguments.  If you pass address ranges like
C<1000.0.0.0/300>, you will probably get weird regexps out.

=head1 FUNCTIONS

=over

=cut

=item create_iprange_regexp($iprange | $hashref | $arrayref, ...)

This function digests IP ranges into a regular expression that can
subsequently be used to efficiently test single IP addresses.  It
returns a regular expression string that can be passed to match_ip().

The simple way to use this is to pass a list of IP ranges as
C.  When used this way, the return value of the
match_ip() function will be simply C<1> or C.

The more complex way is to pass a hash reference of IP range => return
value pairs.  When used this way, the return value of the match_ip()
function will be the specified return value or C for no match.

For example:

    my $re1 = create_iprange_regexp('209.249.163.0/25', '127.0.0.1/32');
    print match_ip('209.249.163.62', $re1); # prints '1'

    my $re2 = create_iprange_regexp({'209.249.163.0/25' => 'clotho.com',
                                     '127.0.0.1/32' => 'localhost'});
    print match_ip('209.249.163.62', $re2); # prints 'clotho.com'

Be aware that the value string will be wrapped in single quotes in the
regexp.  Therefore, you must double-escape any single quotes in that
value.  For example:

    create_iprange_regexp({'208.201.239.36/31' => 'O\\'Reilly publishing'});

Note that the scalar and hash styles can be mixed (a rarely used
feature).  These two examples are equivalent:

    create_iprange_regexp('127.0.0.1/32',
                          {'209.249.163.0/25' => 'clotho.com'},
                          '10.0.0.0/8',
                          {'192.168.0.0/16' => 'LAN'});

    create_iprange_regexp({'127.0.0.1/32' => 1,
                           '209.249.163.0/25' => 'clotho.com',
                           '10.0.0.0/8' => 1,
                           '192.168.0.0/16' => 'LAN'});

If any of the IP ranges are overlapping, the broadest one is used.  If
they are equivalent, then the first one passed is used.  If you have
some data that might be ambiguous, you pass an arrayref instead of a
hashref, but it's better to clean up your data instead!  For example:

    my $re = create_iprange_regexp(['1.1.1.0/31' => 'zero', '1.1.1.1/31' => 'one']);
    print match_ip('1.1.1.1', $re));   # prints 'zero', since both match

WARNING: This function does no checking for validity of IP ranges.  It
happily accepts C<1000.0.0.0/-38> and makes a garbage regexp.
Hopefully a future version will validate the ranges, perhaps via
Net::CIDR or Net::IP.

=cut

sub create_iprange_regexp {   ##no critic (ArgUnpacking)
   return _build_regexp(0, \@_);
}

=item create_iprange_regexp_depthfirst($iprange | $hashref | $arrayref, ...)

Returns a regexp in matches the most specific IP range instead of the
broadest range.  Example:

    my $re = create_iprange_regexp_depthfirst({'192.168.0.0/16' => 'LAN',
                                               '192.168.0.1' => 'router'});
    match_ip('192.168.0.1', $re);

returns 'router' instead of 'LAN'.

=cut

sub create_iprange_regexp_depthfirst {   ##no critic (ArgUnpacking)
   return _build_regexp(1, \@_);
}
sub _build_regexp {
   my ($depthfirst, $ipranges) = @_;

   # If an argument is a hash or array ref, flatten it
   # If an argument is a scalar, make it a key and give it a value of 1
   my @map
       = map {   ! ref $_            ? ( $_ => 1 )
               :   ref $_ eq 'ARRAY' ? @{$_}
               :                       %{$_}         } @{$ipranges};

   # The tree is a temporary construct.  It has three possible
   # properties: 0, 1, and code.  The code is the return value for a
   # match.
   my %tree;

IPRANGE:
   for ( my $i = 0; $i < @map; $i += 2 ) {
      my $range = $map[ $i ];
      my $match = $map[ $i + 1 ];

      my ( $ip, $mask ) = split m/\//xms, $range;
      if (! defined $mask) {
         $mask = 32;          ## no critic(MagicNumbers)
      }

      my $tree = \%tree;
      my @bits = split m//xms, unpack 'B32', pack 'C4', split m/[.]/xms, $ip;

      for my $bit ( @bits[ 0 .. $mask - 1 ] ) {

         # If this case is hit, it means that our IP range is a subset
         # of some other range, and thus ignorable
         next IPRANGE if !$depthfirst && $tree->{code};

         $tree->{$bit} ||= {};    # Turn a leaf into a branch, if needed
         $tree = $tree->{$bit};   # Follow one branch
      }

      # Our $tree is now a leaf node of %tree.  Set its value
      # If the code is already set, it's a non-fatal error (redundant data)
      $tree->{code} ||= $match;

      # Ignore case where $tree->{0} or $tree->{1} are set (i.e. if
      # the current range encompasses any earlier-processed ranges).
      # Those branches will be ignored in _tree2re()
   }

   # Recurse into the tree making it into a regexp
   my $re = join q{}, '^4', $depthfirst ? _tree2re_depthfirst( \%tree ) : _tree2re( \%tree );

   ## Performance optimization:

   # If we are going to use the pattern repeatedly, it's more
   # effiecient if it's already a regexp instead of a string.
   # Otherwise, it needs to be compiled in each invocation of
   # match_ip().  If the regexp is merely stored and not used then
   # this is wasted effort.

   use re 'eval';    # needed because we're interpolating into a regexp
   $re = qr/$re/xms;

   return $re;
}

=item match_ip($ipaddr, $regexp)

Given a single IP address as a string of the form C
and a regular expression string (typically the output of
create_iprange_regexp()), this function returns a specified value
(typically C<1>) if the IP is in one of the ranges, or C if no
ranges match.

See create_ipranges_regexp() for more details about the return value
of this function.

WARNING: This function does no checking for validity of the IP address.

=cut

sub match_ip {
   my ( $ip, $re ) = @_;

   return if !$ip;
   return if !$re;

   local $LAST_REGEXP_CODE_RESULT = undef;
   use re 'eval';
   ( '4' . unpack 'B32', pack 'C4', split m/[.]/xms, $ip ) =~ m/$re/xms;
   return $LAST_REGEXP_CODE_RESULT;
}

# Helper function.  This recurses to build the regular expression
# string from a tree of IP ranges constructed by
# create_iprange_regexp().

sub _tree2re {
   my ( $tree ) = @_;

   return
       defined $tree->{code}       ? ( "(?{'$tree->{code}'})"            )  # Match
       : $tree->{0} && $tree->{1}  ? ( '(?>0', _tree2re($tree->{0}),
                                         '|1', _tree2re($tree->{1}), ')' )  # Choice
       : $tree->{0}                ? (    '0', _tree2re($tree->{0})      )  # Literal, no choice
       : $tree->{1}                ? (    '1', _tree2re($tree->{1})      )  # Literal, no choice
       : die 'Internal error: failed to create a regexp from the supplied IP ranges'
       ;
}

sub _tree2re_depthfirst {
   my ( $tree ) = @_;

   if (defined $tree->{code}) {
      return '(?>',
         $tree->{0} && $tree->{1}  ? ( '(?>0', _tree2re_depthfirst($tree->{0}),
                                         '|1', _tree2re_depthfirst($tree->{1}), ')|' )
       : $tree->{0}                ? (    '0', _tree2re_depthfirst($tree->{0}), q{|} )
       : $tree->{1}                ? (    '1', _tree2re_depthfirst($tree->{1}), q{|} )
       : (),
       "(?{'$tree->{code}'}))";
   } else {
      return
         $tree->{0} && $tree->{1}  ? ( '(?>0', _tree2re_depthfirst($tree->{0}),
                                         '|1', _tree2re_depthfirst($tree->{1}), ')' )  # Choice
       : $tree->{0}                ? (    '0', _tree2re_depthfirst($tree->{0})      )  # Literal, no choice
       : $tree->{1}                ? (    '1', _tree2re_depthfirst($tree->{1})      )  # Literal, no choice
       : die 'Internal error: failed to create a regexp from the supplied IP ranges'
       ;
   }
}

1;

__END__