service_wopi/lib/Discovery/DiscoveryClient.php

<?php

declare(strict_types=1);

namespace KTXM\ServiceWopi\Discovery;

use RuntimeException;

class DiscoveryClient
{
    public function fetch(ServerAddress $server): DiscoveryDocument
    {
        $curl = curl_init($server->discoveryUrl());
        $xml = '';
        curl_setopt_array($curl, [
            CURLOPT_CONNECTTIMEOUT => 5,
            CURLOPT_TIMEOUT => 15,
            CURLOPT_FOLLOWLOCATION => false,
            CURLOPT_PROTOCOLS => CURLPROTO_HTTPS,
            CURLOPT_SSL_VERIFYPEER => true,
            CURLOPT_SSL_VERIFYHOST => 2,
            CURLOPT_HTTPHEADER => ['Accept: application/xml, text/xml'],
            CURLOPT_WRITEFUNCTION => static function ($handle, string $chunk) use (&$xml): int {
                if (strlen($xml) + strlen($chunk) > DiscoveryDocument::MAX_BYTES) { return 0; }
                $xml .= $chunk;
                return strlen($chunk);
            },
        ]);
        try {
            $ok = curl_exec($curl);
            $status = curl_getinfo($curl, CURLINFO_RESPONSE_CODE);
            if ($ok === false) {
                throw new RuntimeException('Discovery request failed (cURL ' . curl_errno($curl) . '). Check DNS, TLS, connectivity, and response size.');
            }
            if ($status !== 200) {
                throw new RuntimeException('Discovery returned HTTP ' . $status
                    . ($status === 404 ? '. Enable WOPI and forward /hosting/discovery through the proxy.' : '. Expected HTTP 200; redirects are not followed.'));
            }
            return DiscoveryDocument::parse($xml, $server);
        } finally {
            curl_close($curl);
        }
    }
}