PHP verify valid UUID

Question

I found the following Javascript function in another answer:

function createUUID() {
    var s = [];
    var hexDigits = "0123456789abcdef";

    for (var i = 0; i < 36; i++) {
        s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1);
    }

    s[14] = "4";
    s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1);
    s[8] = s[13] = s[18] = s[23] = "-";

    var uuid = s.join("");
    return uuid;
}

This creates an RFC valid UUID/GUID in javascript.. What I want to know is if there is a way to validate the string once it arrives to the PHP side. I found a regex that would potentially validate everything roughly that format as true:

/^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$/

but using that as long as you specified a string of equal length and format it would pass validation.

Is there any way to add some sort of seed to the javascript function and then verify that in the PHP or if there was a way for PHP to validate the number that was passed matches with the correct format or something?

Any help is greatly appreciated.

Answer 1

According to Wikipedia the format of UUID v4 is:

Version 4 UUIDs have the form xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is any hexadecimal digit and y is one of 8, 9, A, or B. e.g. f47ac10b-58cc-4372-a567-0e02b2c3d479.

The corresponding regex is:

/^[0-9A-F]{8}-[0-9A-F]{4}-4[0-9A-F]{3}-[89AB][0-9A-F]{3}-[0-9A-F]{12}$/i

Answer 2

I use regex validation along with string validation to check if the given string is in valid UUID format.

if (!is_string($uuid) || (preg_match('/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/', $uuid) !== 1)) {
    return false;
}

You can see the full gist here.

Answer 3

You should use regex. For this, you can use this quick regex:

/^[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}$/i

It ignore the case of chars, and works the same a some regex which are longer.

You can find full explaination here.

To use it, you can do:

if(is_string($uuid) && preg_match('/^[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}$/i', $uuid)) {
   // your code here
}

Answer 4

I am using this function. I found the regex from github from the link on the comments. It also seems to be faster than many others.

/**
 * @link https://gist.github.com/Joel-James/3a6201861f12a7acf4f2?permalink_comment_id=3030120#gistcomment-3030120
 */
public static function isValidUUID(string $uuid): bool
{
    return preg_match('/^[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}$/i', $uuid) !== 1 ? false : true;
}