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<?php
declare(strict_types=1);
/**
* SPDX-FileCopyrightText: 2021 Nextcloud GmbH and Nextcloud contributors
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
namespace OC\Http\Client;
use OC\Net\IpAddressClassifier;
use OCP\Http\Client\LocalServerException;
use Psr\Http\Message\RequestInterface;
class DnsPinMiddleware {
/** @var NegativeDnsCache */
private $negativeDnsCache;
private IpAddressClassifier $ipAddressClassifier;
public function __construct(
NegativeDnsCache $negativeDnsCache,
IpAddressClassifier $ipAddressClassifier
) {
$this->negativeDnsCache = $negativeDnsCache;
$this->ipAddressClassifier = $ipAddressClassifier;
}
/**
* Fetch soa record for a target
*
* @param string $target
* @return array|null
*/
private function soaRecord(string $target): ?array {
$labels = explode('.', $target);
$top = count($labels) >= 2 ? array_pop($labels) : '';
$second = array_pop($labels);
$hostname = $second . '.' . $top;
$responses = $this->dnsGetRecord($hostname, DNS_SOA);
if ($responses === false || count($responses) === 0) {
return null;
}
return reset($responses);
}
private function dnsResolve(string $target, int $recursionCount) : array {
if ($recursionCount >= 10) {
return [];
}
$recursionCount++;
$targetIps = [];
$soaDnsEntry = $this->soaRecord($target);
$dnsNegativeTtl = $soaDnsEntry['minimum-ttl'] ?? null;
$canHaveCnameRecord = true;
$dnsTypes = \defined('AF_INET6') || @inet_pton('::1')
? [DNS_A, DNS_AAAA, DNS_CNAME]
: [DNS_A, DNS_CNAME];
foreach ($dnsTypes as $dnsType) {
if ($canHaveCnameRecord === false && $dnsType === DNS_CNAME) {
continue;
}
if ($this->negativeDnsCache->isNegativeCached($target, $dnsType)) {
continue;
}
$dnsResponses = $this->dnsGetRecord($target, $dnsType);
if ($dnsResponses !== false && count($dnsResponses) > 0) {
foreach ($dnsResponses as $dnsResponse) {
if (isset($dnsResponse['ip'])) {
$targetIps[] = $dnsResponse['ip'];
$canHaveCnameRecord = false;
} elseif (isset($dnsResponse['ipv6'])) {
$targetIps[] = $dnsResponse['ipv6'];
$canHaveCnameRecord = false;
} elseif (isset($dnsResponse['target']) && $canHaveCnameRecord) {
$targetIps = array_merge($targetIps, $this->dnsResolve($dnsResponse['target'], $recursionCount));
}
}
} elseif ($dnsNegativeTtl !== null) {
$this->negativeDnsCache->setNegativeCacheForDnsType($target, $dnsType, $dnsNegativeTtl);
}
}
return $targetIps;
}
/**
* Wrapper for dns_get_record
*/
protected function dnsGetRecord(string $hostname, int $type): array|false {
return \dns_get_record($hostname, $type);
}
public function addDnsPinning() {
return function (callable $handler) {
return function (
RequestInterface $request,
array $options
) use ($handler) {
if ($options['nextcloud']['allow_local_address'] === true) {
return $handler($request, $options);
}
$hostName = (string)$request->getUri()->getHost();
$port = $request->getUri()->getPort();
$ports = [
'80',
'443',
];
if ($port !== null) {
$ports[] = (string)$port;
}
$targetIps = $this->dnsResolve(idn_to_utf8($hostName), 0);
if (empty($targetIps)) {
throw new LocalServerException('No DNS record found for ' . $hostName);
}
$curlResolves = [];
foreach ($ports as $port) {
$curlResolves["$hostName:$port"] = [];
foreach ($targetIps as $ip) {
if ($this->ipAddressClassifier->isLocalAddress($ip)) {
// TODO: continue with all non-local IPs?
throw new LocalServerException('Host "'.$ip.'" ('.$hostName.':'.$port.') violates local access rules');
}
$curlResolves["$hostName:$port"][] = $ip;
}
}
// Coalesce the per-host:port ips back into a comma separated list
foreach ($curlResolves as $hostport => $ips) {
$options['curl'][CURLOPT_RESOLVE][] = "$hostport:" . implode(',', $ips);
}
return $handler($request, $options);
};
};
}
}
|
