BookStack/app/Util/UrlComparison.php

<?php

namespace BookStack\Util;

class UrlComparison
{
    public function __construct(
        protected readonly string $a,
        protected readonly string $b,
    ) {
    }

    /**
     * Check if the two URLs have the same origin.
     */
    public function originsMatch(): bool
    {
        $aParts = parse_url($this->a);
        $bParts = parse_url($this->b);

        return $aParts['host'] === $bParts['host']
            && $aParts['scheme'] === $bParts['scheme']
            && $aParts['port'] === $bParts['port'];
    }

    /**
     * Check if there's some overlap between the two URLs' paths.
     */
    public function pathsOverlap(): bool
    {
        $aPath = parse_url($this->a, PHP_URL_PATH) ?? '';
        $bPath = parse_url($this->b, PHP_URL_PATH) ?? '';

        return str_starts_with($aPath, $bPath) || str_starts_with($bPath, $aPath);
    }
}