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One often works with IP addresses in packed form which allows for a very efficient regex match:

sub is_private { my ($packed_ip) = @_; return $packed_ip =~ m{ ^ (?: \x0A # 10.0.0.0/8 | \xAC[\x10-\x1F] # 172.16.0.0/12 | \xC0\xA8 # 192.168.0.0/16 ) }x; }

Test:

use strict; use warnings; use Socket qw( inet_aton ); sub is_private { my ($packed_ip) = @_; return $packed_ip =~ m{ ^ (?: \x0A # 10.0.0.0/8 | \xAC[\x10-\x1F] # 172.16.0.0/12 | \xC0\xA8 # 192.168.0.0/16 ) }x; } my $result = ''; for (qw( 9.255.255.255 10.0.0.0 10.255.255.255 11.0.0.0 172.15.255.255 172.16.0.0 172.31.255.255 172.32.0.0 192.167.255.255 192.168.0.0 192.168.255.255 192.169.0.0 )) { my $packed_ip = inet_aton($_); $result .= is_private($packed_ip) ? 1 : 0; } print("got: $result\n"); print("expect: ", "0110"x3, "\n");
got: 011001100110 expect: 011001100110

Update: Alternatives:

sub is_private { my ($packed_ip) = @_; return ($packed_ip & "\xFF\x00\x00\x00") eq "\x0A\x00\x00\x00" || ($packed_ip & "\xFF\xF0\x00\x00") eq "\xAC\x10\x00\x00" || ($packed_ip & "\xFF\xFF\x00\x00") eq "\xC0\xA8\x00\x00"; }
sub is_private { my $nummy_ip = unpack('N', shift); return ($nummy_ip & 0xFF000000) == 0x0A000000 # 10.0.0.0/8 || ($nummy_ip & 0xFFF00000) == 0xAC100000 # 172.16.0.0/12 || ($nummy_ip & 0xFFFF0000) == 0xC0A80000; # 192.168.0.0/16 }
use Inline CPP => <<'__EOI__'; // Assumes the arg had UTF8=0 IV is_private(const char* packed_ip) { // XXX Alignment issues const U16& hi = *(const U16*)packed_ip; // The irrelevant branch will be optimised away. if (*(const U16*)("\x12\x34") == 0x1234) { // Little endian if ( hi == 0xC0A8 || (hi & 0xFFF0) == 0xAC10 || (hi & 0xFF00) == 0x0A00 ) return 1; } else { // Little endian if ( hi == 0xA8C0 || (hi & 0xF0FF) == 0x10AC || (hi & 0x00FF) == 0x000A ) return 1; } return 0; } __EOI__

In reply to Re: Regexp: Private IP Addresses by ikegami
in thread Regexp: Private IP Addresses by Anonymous Monk

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