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2023-09-06 10:22:36 +02:00

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.. _security:
========
Security
========
.. _programmatic-rate-limiting:
Rate Limiting
-------------
Rate limiting can be used to restrict how often someone can execute an operation in a defined time frame. For app framework controllers it is recommended to use rate limiting attributes.
Outside controllers, e.g. in DAV code, it's also possible to guard operations by :ref:`injecting<dependency-injection>` ``\OCP\Security\RateLimiting\ILimiter`` and registering requests *before* the operation:
.. code-block:: php
:emphasize-lines: 13-21, 27-36
<?php
use OCP\Security\RateLimiting\ILimiter;
class MyDavPlugin {
private ILimiter $limiter;
public function __construct(ILimiter $limiter) {
$this->limiter = $limiter;
}
public function calledAnonymously(): void {
try {
$this->limiter->registerAnonRequest(
'my-dav-plugin-anon',
5, // Allow five executions …
60 * 60, // … per hour
);
} catch (IRateLimitExceededException $exception) {
// Respond with a HTTP 429 error
}
// No rate limiting reached. Carry on.
}
public function calledByUser(IUser $user): void {
try {
$this->limiter->registerUserRequest(
'my-dav-plugin-user',
5, // Allow five executions …
60 * 60, // … per hour
$user
);
} catch (IRateLimitExceededException $exception) {
// Respond with a HTTP 429 error
}
// No rate limiting reached. Carry on.
}
}
Remote Host Validation
----------------------
Nextcloud can help validating a remote host so that no internal infrastructure is contacted by user-provided host names or IPs. The validator ``\OCP\Security\IRemoteHostValidator`` can be :ref:`injected<dependency-injection>` into any app class:
.. code-block:: php
<?php
use OCP\Security\IRemoteHostValidator;
class MyRemoteServerIntegration {
private IRemoteHostValidator $hostValidator;
public function __construct(IRemoteHostValidator $hostValidator) {
$this->hostValidator = $hostValidator;
}
public function contactRemoteServer(string $hostname): void {
if (!$this->hostValidator->isValid($hostname)) {
// ABORT
}
// Contact the server
}
}
.. note:: Nextcloud's HTTP clients obtained from ``\OCP\Http\Client\IClientService`` have this validation built in so you don't have to check hosts of HTTP requests as long as you use this provided abstraction.
Trusted domain
----------------
In some cases it might be required that an app checks that a user given link is one of the current instance.
This is possible with the ``OCP\Security\ITrustedDomainHelper``:
.. code-block:: php
<?php
declare(strict_types=1);
use OCP\Security\ITrustedDomainHelper;
$helper = \OC::$server->get(ITrustedDomainHelper::class);
// Compare a full URL example given
$url = 'https://localhost/nextcloud/index.php/apps/files/';
$helper->isTrustedUrl($url);
// Compare a domain and port
$domain = 'example.tld:8443';
$helper->isTrustedDomain($domain);