BookStack/app/Uploads/HttpFetcher.php

<?php

namespace BookStack\Uploads;

use BookStack\Exceptions\HttpFetchException;

class HttpFetcher
{
    /**
     * Fetch content from an external URI.
     *
     * @param string $uri
     *
     * @throws HttpFetchException
     *
     * @return bool|string
     */
    public function fetch(string $uri)
    {
        $ch = curl_init();
        curl_setopt_array($ch, [
            CURLOPT_URL            => $uri,
            CURLOPT_RETURNTRANSFER => 1,
            CURLOPT_CONNECTTIMEOUT => 5,
        ]);

        $data = curl_exec($ch);
        $err = curl_error($ch);
        curl_close($ch);

        if ($err) {
            $errno = curl_errno($ch);
            throw new HttpFetchException($err, $errno);
        }

        return $data;
    }
}