Help comparing IP addresses

[Anon]

I need to be able to take two IP addresses and a netmask and determine if the addresses are compatible. Any ideas appreciated.

[Anon]

function compatible_ips( $ip_str1, $ip_str2, $netmask_str )
{
$netmask = ip2long( $netmask_str );
$ip1 = ip2long( $ip_str1 );
$ip2 = ip2long( $ip_str2 );

return ( $ip1 & $netmask ) == ( $ip2 & $netmask );
}

You can eliminate the first 3 lines if the addresses are already in binary form.

[Anon]

Thanks. Guess I was suffereing from writer's block :-) not thinking about ip2long on the netmask.