Is there a simple way to compare IPs in PHP?

Question

On one hand I have an IP like 123.3.2.3 and I would like to compare it with an array of allowed IPs like:

$allowedIps = ['123.*.*.*', '123.3.2.3', '123.3.2.3::1', '123.3.*.3']

In this case it should match all of the items.

Is there a simple way to do this without having to create a complex string comparison algorithm?

use ```in_array``` php function, here is the reference https://www.w3schools.com/php/func_array_in_array.asp — ashir haroon, Feb 12 '19 at 11:12
One could probably replace out `*` with 0 and 255, then check their range with `ip2long()`. — Qirel, Feb 12 '19 at 11:14
@ashir, That won't work, because we're looking for wildcards, not fixed strings. — Qirel, Feb 12 '19 at 11:15
Do you only use wildcards as ranges, or parts of ranges as well? I.e., would `123.3.2*.*` be valid (here any ip with 2X in the third range, 20-29). — Qirel, Feb 12 '19 at 11:26
123.3.2*.* would be too much to ask I think, if I can manage with 123.3.*.* it'll be more than enough — Raul Leaño Martinet, Feb 12 '19 at 11:32

score 1 · Answer 1 · answered Feb 12 '19 at 11:46

If you don't intend to use wildcards as 123.3.2*.3, which would match any IP between 123.3.20.3 and 123.3.29.3, then the solution below would work fine.

Loop over the IPs in the array, and if there exists a wildcard in it, create two new IPs - one where the wildcard * is replaced by 0, the other replaced by 255. This is the lower and upper limit. Then you convert it to an integer, instead of an IP-string, using the ip2long() function. Do this both on the IP itself, and the value in the array as you loop them.

Then its only a matter of comparing them, that it is in fact between the upper and lower limit.

If there is no wildcard in the string, do a direct comparison.

$allowedIps = ['123.2.*.*', '123.3.2.3', '123.3.*.3'];
$IP = '123.3.1.3';
$match = 0;

foreach ($allowedIps as $allowed) {
    // If there is no wildcard, we check for the specific IP instead, and not a range
    if (strpos($allowed, "*") !== false) {
        $lowest = str_replace("*", "0", $allowed);
        $highest = str_replace("*", "255", $allowed);

        if (ip2long($IP) >= ip2long($lowest) && ip2long($IP) <= ip2long($highest)) {
            echo "$IP matched $allowed";
            $match = 1;
            break;
        }
    } elseif (ip2long($IP) === ip2long($allowed)) {
        echo "Matched ".$allowed;
        $match = 1;
        break;
    }
}

Probably wouldn't even need the condition to check if there are wildcards, as it wouldn't replace anything and both conditions in the subsequent if condition would be true.

ip2long()

Fair warning, I have not fully tested this, and there might be some obscure cases where the conditions might fail. You might be better off doing this outside of PHP as well.

Is there a simple way to compare IPs in PHP?

1 Answers1