Bug in DnsPinMiddleware.php, unable to resolve hostname

[giacomo892]

Steps to reproduce

I'm running Nextcloud 22 on freebsd PHP8 , just upgraded from 21, and it failed

Checking for update of app activity in appstore
An unhandled exception has been thrown:
TypeError: count(): Argument #1 ($value) must be of type Countable|array, bool given in /usr/local/www/owncloud/lib/private/Http/Client/DnsPinMiddleware.php:68
Stack trace:
#0 /usr/local/www/owncloud/lib/private/Http/Client/DnsPinMiddleware.php(68): count()
#1 /usr/local/www/owncloud/lib/private/Http/Client/DnsPinMiddleware.php(111): OC\Http\Client\DnsPinMiddleware->dnsResolve()
#2 /usr/local/www/owncloud/3rdparty/guzzlehttp/guzzle/src/PrepareBodyMiddleware.php(35): OC\Http\Client\DnsPinMiddleware->OC\Http\Client{closure}()
#3 /usr/local/www/owncloud/3rdparty/guzzlehttp/guzzle/src/Middleware.php(31): GuzzleHttp\PrepareBodyMiddleware->__invoke()
#4 /usr/local/www/owncloud/3rdparty/guzzlehttp/guzzle/src/RedirectMiddleware.php(71): GuzzleHttp\Middleware::GuzzleHttp{closure}()
#5 /usr/local/www/owncloud/3rdparty/guzzlehttp/guzzle/src/Middleware.php(63): GuzzleHttp\RedirectMiddleware->__invoke()
#6 /usr/local/www/owncloud/3rdparty/guzzlehttp/guzzle/src/HandlerStack.php(75): GuzzleHttp\Middleware::GuzzleHttp{closure}()
#7 /usr/local/www/owncloud/3rdparty/guzzlehttp/guzzle/src/Client.php(331): GuzzleHttp\HandlerStack->__invoke()
#8 /usr/local/www/owncloud/3rdparty/guzzlehttp/guzzle/src/Client.php(168): GuzzleHttp\Client->transfer()
#9 /usr/local/www/owncloud/3rdparty/guzzlehttp/guzzle/src/Client.php(187): GuzzleHttp\Client->requestAsync()
#10 /usr/local/www/owncloud/lib/private/Http/Client/Client.php(223): GuzzleHttp\Client->request()
#11 /usr/local/www/owncloud/lib/private/App/AppStore/Fetcher/Fetcher.php(108): OC\Http\Client\Client->get()
#12 /usr/local/www/owncloud/lib/private/App/AppStore/Fetcher/AppFetcher.php(79): OC\App\AppStore\Fetcher\Fetcher->fetch()
#13 /usr/local/www/owncloud/lib/private/App/AppStore/Fetcher/Fetcher.php(180): OC\App\AppStore\Fetcher\AppFetcher->fetch()
#14 /usr/local/www/owncloud/lib/private/Installer.php(434): OC\App\AppStore\Fetcher\Fetcher->get()
#15 /usr/local/www/owncloud/lib/private/Updater.php(420): OC\Installer->isUpdateAvailable()
#16 /usr/local/www/owncloud/lib/private/Updater.php(268): OC\Updater->upgradeAppStoreApps()
#17 /usr/local/www/owncloud/lib/private/Updater.php(130): OC\Updater->doUpgrade()
#18 /usr/local/www/owncloud/core/Command/Upgrade.php(241): OC\Updater->upgrade()
#19 /usr/local/www/owncloud/3rdparty/symfony/console/Command/Command.php(255): OC\Core\Command\Upgrade->execute()
#20 /usr/local/www/owncloud/3rdparty/symfony/console/Application.php(1009): Symfony\Component\Console\Command\Command->run()
#21 /usr/local/www/owncloud/3rdparty/symfony/console/Application.php(273): Symfony\Component\Console\Application->doRunCommand()
#22 /usr/local/www/owncloud/3rdparty/symfony/console/Application.php(149): Symfony\Component\Console\Application->doRun()
#23 /usr/local/www/owncloud/lib/private/Console/Application.php(209): Symfony\Component\Console\Application->run()
#24 /usr/local/www/owncloud/console.php(99): OC\Console\Application->run()
#25 /usr/local/www/owncloud/occ(11): require_once('/usr/local/www/...')

Turns out the issue is in DnsPinMiddleware.php.
Basically there

$dnsTypes = [DNS_A, DNS_AAAA, DNS_CNAME];
foreach ($dnsTypes as $key => $dnsType) {
if ($this->negativeDnsCache->isNegativeCached($target, $dnsType)) {
unset($dnsTypes[$key]);
continue;
}

assuming the $target is apps.nextcloud.com after that part of the code the $target will be apps.nextcloud.comapps.nextcloud.comapps.nextcloud.com which will make the dns resolver to fail.

Sorry for the short report but I am running out of time.

[kesselb]

assuming the $target is apps.nextcloud.com after that part of the code the $target will be apps.nextcloud.comapps.nextcloud.comapps.nextcloud.com which will make the dns resolver to fail.

Are you sure? I don't see that we modify $target in the above code.

[kesselb]

server/lib/private/Http/Client/DnsPinMiddleware.php

Lines 83 to 85 in c2f62ee

	$dnsResponses = dns_get_record($target, $dnsType);
	$canHaveCnameRecord = true;
	if (count($dnsResponses) > 0) {

dns_get_record may return false (if for whatever reason resolving the dns record is not possible). In the above code a check if $dnsResponses is false is missing. count(false) will raise a "must be of type Countable|array," warning because false is not countable.

But there is still something different broken as resolving a dns record failed. #27873 is the same error also for FreeBSD. I remember some issues with OpenSSL due some security hardening on FreeBSD. Is it possible that resolving dns records is forbidden on your setup (for php applications).

To test if getting dns records work in general with: php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_A));"

[giacomo892]

@kesselb Your command executes just fine. Infact that's how I manage to finish the upgrade, I've changed
$dnsTypes = [DNS_A, DNS_AAAA, DNS_CNAME];
to
$dnsTypes = [DNS_A];

and it worked

$ php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_A));"
array(1) {
  [0]=>
  array(5) {
    ["host"]=>
    string(18) "apps.nextcloud.com"
    ["class"]=>
    string(2) "IN"
    ["ttl"]=>
    int(3600)
    ["type"]=>
    string(1) "A"
    ["ip"]=>
    string(12) "176.9.217.53"
  }
}

assuming the $target is apps.nextcloud.com after that part of the code the $target will be apps.nextcloud.comapps.nextcloud.comapps.nextcloud.com which will make the dns resolver to fail.

Are you sure? I don't see that we modify $target in the above code.

Quite, I added a print statement in the code.

[kesselb]

php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_A));"
php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_AAAA));"
php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_CNAME));"
php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_A | DNS_AAAA | DNS_CNAME));"

Would you mind to do another test round? ;)

[giacomo892]

@kesselb Sure!

php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_A));"
array(1) {
  [0]=>
  array(5) {
    ["host"]=>
    string(18) "apps.nextcloud.com"
    ["class"]=>
    string(2) "IN"
    ["ttl"]=>
    int(3600)
    ["type"]=>
    string(1) "A"
    ["ip"]=>
    string(12) "176.9.217.53"
  }
}
$ php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_AAAA));"
array(1) {
  [0]=>
  array(5) {
    ["host"]=>
    string(18) "apps.nextcloud.com"
    ["class"]=>
    string(2) "IN"
    ["ttl"]=>
    int(3600)
    ["type"]=>
    string(4) "AAAA"
    ["ipv6"]=>
    string(21) "2a01:4f8:130:32f1::53"
  }
}
$ php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_CNAME));"
PHP Warning:  dns_get_record(): DNS Query failed in Command line code on line 1
bool(false)
$ php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_A | DNS_AAAA | DNS_CNAME));"
PHP Warning:  dns_get_record(): DNS Query failed in Command line code on line 1
bool(false)

[ntinti]

Same here on FreeBSD 12.2. with NC 22.0 - Problem is "CNAME"

php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_A));"
array(1) {
[0]=>
array(5) {
["host"]=>
string(18) "apps.nextcloud.com"
["class"]=>
string(2) "IN"
["ttl"]=>
int(1789)
["type"]=>
string(1) "A"
["ip"]=>
string(12) "176.9.217.53"
}
}
php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_AAAA));"
array(1) {
[0]=>
array(5) {
["host"]=>
string(18) "apps.nextcloud.com"
["class"]=>
string(2) "IN"
["ttl"]=>
int(104)
["type"]=>
string(4) "AAAA"
["ipv6"]=>
string(21) "2a01:4f8:130:32f1::53"
}
}
php -r "var_dump(dns_get_record('apps.nextcloud.com', DNS_CNAME));"
bool(false)

[l1gi]

Same problem. Quick workaround:

--- /usr/local/www/nextcloud/lib/private/Http/Client/DnsPinMiddleware.php.orig  2021-07-12 09:23:37.206156000 +0200
+++ /usr/local/www/nextcloud/lib/private/Http/Client/DnsPinMiddleware.php       2021-07-12 09:19:34.353092000 +0200
@@ -65,7 +65,7 @@
 
                        $dnsResponses = dns_get_record($target, $dnsType);
                        $canHaveCnameRecord = true;
-                       if (count($dnsResponses) > 0) {
+                       if ($dnsResponse && count($dnsResponses) > 0) {
                                foreach ($dnsResponses as $key => $dnsResponse) {
                                        if (isset($dnsResponse['ip'])) {
                                                $targetIps[] = $dnsResponse['ip'];