[FEATURE] Add RateLimit spam check method

cweiske · cweiske · commit 37645f2ca280 · 2025-11-17T15:22:24.000+01:00
A new spam prevention method that marks form submissions as spam
when a user submits forms too often in a given time frame,
e.g. 10x in 5 minutes.
This helps reducing spam flood attacks, because only the first
submissions will be allowed.

The RateLimitMethod utilizes the Symfony rate limiter
that is already used by the TYPO3 backend login to prevent brute-force
attacks.

Only valid form submissions are counted toward the rate limit.
This requires splitting the rate limit check (RateLimitMethod)
from the actual rate limit consumption (RateLimitFinisher).

Both interval and limit are configurable via TypoScript.
All valid DateTimeInterval strings are accepted, allowing interval
declarations like "10 minutes" or "5 hours".

Configuring the properties for rate limiting identifier is possible:
Either rate limit all submissions from an IP address,
or rate limit submissions from an IP to a certain form only.
Adding form field values is possible as well, preventing
duplicate submissions from e.g. an e-mail addresses.

Rate limit information is stored via TYPO3's caching framework in the
'ratelimiter' cache. This allows admins to share the limit across
multiple machines by configuring it to use a database or redis backend.

Heavily inspired by Chris Müller's brotkrueml/typo3-form-rate-limit
extension.
diff --git a/.project/tests/phpstan-baseline.neon b/.project/tests/phpstan-baseline.neon
@@ -1945,6 +1945,11 @@ parameters:
 			count: 3
 			path: ../../Classes/Domain/Validator/SpamShield/NameMethod.php
 
+		-
+			message: "#^Cannot call method getUid\\(\\) on In2code\\\\Powermail\\\\Domain\\\\Model\\\\Form\\|TYPO3\\\\CMS\\\\Extbase\\\\Persistence\\\\Generic\\\\LazyLoadingProxy\\|null\\.$#"
+			count: 1
+			path: ../../Classes/Domain/Validator/SpamShield/RateLimitMethod.php
+
 		-
 			message: "#^Cannot call method getUid\\(\\) on In2code\\\\Powermail\\\\Domain\\\\Model\\\\Form\\|TYPO3\\\\CMS\\\\Extbase\\\\Persistence\\\\Generic\\\\LazyLoadingProxy\\|null\\.$#"
 			count: 1
diff --git a/Classes/Domain/Validator/SpamShield/RateLimitMethod.php b/Classes/Domain/Validator/SpamShield/RateLimitMethod.php
@@ -0,0 +1,173 @@
+<?php
+
+declare(strict_types=1);
+namespace In2code\Powermail\Domain\Validator\SpamShield;
+
+use In2code\Powermail\Finisher\RateLimitFinisher;
+use In2code\Powermail\Storage\RateLimitStorage;
+use Symfony\Component\RateLimiter\RateLimiterFactory;
+use TYPO3\CMS\Core\Utility\GeneralUtility;
+
+/**
+ * Limit the number of submissions in a given time frame.
+ *
+ * Marks the submission as spam if the rate limit has been reached.
+ * Counting a submission against the rate limit is done in RateLimitFinisher.
+ *
+ * Exclusion of IP addresses is possible with a powermail breaker configuration.
+ */
+class RateLimitMethod extends AbstractMethod
+{
+    /**
+     * Check if this form submission is limited or shall be allowed.
+     *
+     * @return bool true if spam recognized
+     */
+    public function spamCheck(): bool
+    {
+        $config = [
+            'id'       => 'powermail-ratelimit',
+            'policy'   => 'sliding_window',
+            'limit'    => $this->getLimit(),
+            'interval' => $this->getInterval(),
+        ];
+
+        $storage = GeneralUtility::makeInstance(RateLimitStorage::class);
+
+        $factory = new RateLimiterFactory($config, $storage);
+
+        $keyParts = $this->getRestrictionValues($this->getRestrictions());
+        $key = implode('-', $keyParts);
+
+        $limiter = $factory->create($key);
+        RateLimitFinisher::markForConsumption($limiter);
+
+        if ($limiter->consume(0)->getRemainingTokens() > 0) {
+            return false;
+        }
+
+        //spam
+        return true;
+    }
+
+    /**
+     * Replace the restriction variables with their values
+     *
+     * @param string[] $restrictions
+     *
+     * @return string[]
+     */
+    protected function getRestrictionValues(array $restrictions): array
+    {
+        $answers = $this->mail->getAnswersByFieldMarker();
+
+        $values = [];
+        foreach ($restrictions as $restriction) {
+            if ($restriction === '__ipAddress') {
+                $values[$restriction] = GeneralUtility::getIndpEnv('REMOTE_ADDR');
+            } elseif ($restriction === '__formIdentifier') {
+                $values[$restriction] = $this->mail->getForm()->getUid();
+            } elseif ($restriction[0] === '{') {
+                //form field
+                $fieldName = substr($restriction, 1, -1);
+                if (!isset($answers[$fieldName])) {
+                    throw new \InvalidArgumentException('Form has no field with variable name ' . $fieldName, 1763046923);
+                }
+                $values[$restriction] = $answers[$fieldName]->getValue();
+            } else {
+                //hard-coded value
+                $values[$restriction] = $restriction;
+            }
+        }
+
+        return $values;
+    }
+
+    /**
+     * Get the configured time interval in which the limit has to be adhered to
+     */
+    protected function getInterval(): string
+    {
+        $interval = $this->configuration['interval'];
+
+        if ($interval === null) {
+            throw new \InvalidArgumentException('Interval must be set!', 1671448702);
+        }
+        if (! \is_string($interval)) {
+            throw new \InvalidArgumentException('Interval must be a string!', 1671448703);
+        }
+
+        if (@\DateInterval::createFromDateString($interval) === false) {
+            // @todo Remove check and exception when compatibility of PHP >= 8.3
+            // @see https://www.php.net/manual/de/class.datemalformedintervalstringexception.php
+            throw new \InvalidArgumentException(
+                \sprintf(
+                    'Interval is not valid, "%s" given!',
+                    $interval,
+                ),
+                1671448704,
+            );
+        }
+
+        return $interval;
+    }
+
+    /**
+     * Get how many form submissions are allowed within the time interval
+     */
+    protected function getLimit(): int
+    {
+        $limit = $this->configuration['limit'];
+
+        if ($limit === null) {
+            throw new \InvalidArgumentException('Limit must be set!', 1671449026);
+        }
+
+        if (! \is_numeric($limit)) {
+            throw new \InvalidArgumentException('Limit must be numeric!', 1671449027);
+        }
+
+        $limit = (int)$limit;
+        if ($limit < 1) {
+            throw new \InvalidArgumentException('Limit must be greater than 0!', 1671449028);
+        }
+
+        return $limit;
+    }
+
+    /**
+     * Get the list of properties that are used to identify the form
+     *
+     * Supported values:
+     * - __ipAddress
+     * - __formIdentifier
+     * - {email} - Form field names
+     * - foo - Hard-coded values
+     *
+     * @return string[]
+     */
+    protected function getRestrictions(): array
+    {
+        $restrictions = $this->configuration['restrictions'];
+
+        if ($restrictions === null) {
+            throw new \InvalidArgumentException('Restrictions must be set!', 1671727527);
+        }
+
+        if (! \is_array($restrictions)) {
+            throw new \InvalidArgumentException('Restrictions must be an array!', 1671727528);
+        }
+
+        if ($restrictions === []) {
+            throw new \InvalidArgumentException('Restrictions must not be an empty array!', 1671727529);
+        }
+
+        foreach ($restrictions as $restriction) {
+            if (! \is_string($restriction)) {
+                throw new \InvalidArgumentException('A single restrictions must be a string!', 1671727530);
+            }
+        }
+
+        return \array_values($restrictions);
+    }
+}
diff --git a/Classes/Finisher/RateLimitFinisher.php b/Classes/Finisher/RateLimitFinisher.php
@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+namespace In2code\Powermail\Finisher;
+
+use Symfony\Component\RateLimiter\LimiterInterface;
+
+/**
+ * Count the form submission against the rate limit.
+ *
+ * Only valid form submissions count against the rate limit.
+ * This is implemented by checking for available tokens in the
+ * RateLimitMethod spam shield, but consuming the tokens here.
+ *
+ * @link https://symfony.com/doc/7.3/rate_limiter.html
+ */
+class RateLimitFinisher extends AbstractFinisher
+{
+    /**
+     * All the limiters that shall be consumed when the form is submitted.
+     *
+     * @var LimiterInterface[]
+     */
+    protected static array $limiters = [];
+
+    /**
+     * Marks the limiter as to be consumed when the mail is accepted and stored.
+     */
+    public static function markForConsumption(LimiterInterface $limiter): void
+    {
+        static::$limiters[] = $limiter;
+    }
+
+    /**
+     * Consume a token for each rate limiter.
+     */
+    public function consumeLimitersFinisher(): void
+    {
+        foreach (static::$limiters as $limiter) {
+            $limiter->consume(1);
+        }
+    }
+}
diff --git a/Classes/Storage/RateLimitStorage.php b/Classes/Storage/RateLimitStorage.php
@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace In2code\Powermail\Storage;
+
+use Symfony\Component\RateLimiter\LimiterStateInterface;
+use Symfony\Component\RateLimiter\Policy\SlidingWindow;
+use Symfony\Component\RateLimiter\Policy\TokenBucket;
+use Symfony\Component\RateLimiter\Policy\Window;
+use Symfony\Component\RateLimiter\Storage\StorageInterface;
+use TYPO3\CMS\Core\Cache\CacheManager;
+use TYPO3\CMS\Core\Cache\Frontend\FrontendInterface;
+
+/**
+ * Copy of TYPO3's internal CachingFrameworkStorage.
+ *
+ * \TYPO3\CMS\Core\RateLimiter\Storage\CachingFrameworkStorage
+ */
+class RateLimitStorage implements StorageInterface
+{
+    private FrontendInterface $cacheInstance;
+
+    public function __construct(CacheManager $cacheInstance)
+    {
+        $this->cacheInstance = $cacheInstance->getCache('ratelimiter');
+        $this->cacheInstance->collectGarbage();
+    }
+
+    public function save(LimiterStateInterface $limiterState): void
+    {
+        $this->cacheInstance->set(
+            sha1($limiterState->getId()),
+            serialize($limiterState),
+            [],
+            $limiterState->getExpirationTime()
+        );
+    }
+
+    public function fetch(string $limiterStateId): ?LimiterStateInterface
+    {
+        $cacheItem = $this->cacheInstance->get(sha1($limiterStateId));
+        if ($cacheItem) {
+            $value = unserialize($cacheItem, ['allowed_classes' => [Window::class, SlidingWindow::class, TokenBucket::class]]);
+            if ($value instanceof LimiterStateInterface) {
+                return $value;
+            }
+        }
+
+        return null;
+    }
+
+    public function delete(string $limiterStateId): void
+    {
+        $this->cacheInstance->remove(sha1($limiterStateId));
+    }
+}
diff --git a/Configuration/Services.yaml b/Configuration/Services.yaml
@@ -46,3 +46,6 @@ services:
       - name: 'event.listener'
         identifier: 'powermail/modify-data-structure'
         method: 'modifyDataStructure'
+
+  In2code\Powermail\Storage\RateLimitStorage:
+    public: true
diff --git a/Configuration/TypoScript/Main/Configuration/12_Spamshield.typoscript b/Configuration/TypoScript/Main/Configuration/12_Spamshield.typoscript
@@ -185,6 +185,38 @@ plugin.tx_powermail.settings.setup {
           values.value = 123.132.125.123,123.132.125.124
         }
       }
+
+      # Rate limiter
+      8 {
+        _enable = 1
+
+        # Spamcheck name
+        name = IP rate limiter
+
+        # Class
+        class = In2code\Powermail\Domain\Validator\SpamShield\RateLimitMethod
+
+        # if this check fails - add this indication value to indicator (0 disables this check completely)
+        indication = 100
+
+        # method configuration
+        configuration {
+          #see "DateTimeInterval" class for allowed values
+          interval = 5 minutes
+
+          #number of form sumissions within the interval
+          limit = 10
+
+          # Parts of the rate limiting key
+          # - placeholders: __ipAddress, __formIdentifier
+          # - form values: {email}
+          # - hard coded values: foo
+          restrictions {
+            10 = __ipAddress
+            20 = __formIdentifier
+          }
+        }
+      }
     }
   }
 }
diff --git a/Configuration/TypoScript/Main/Configuration/30_Finisher.typoscript b/Configuration/TypoScript/Main/Configuration/30_Finisher.typoscript
@@ -4,6 +4,7 @@
 plugin.tx_powermail.settings.setup {
   finishers {
     # Powermail finishers
+    0.class = In2code\Powermail\Finisher\RateLimitFinisher
     10.class = In2code\Powermail\Finisher\SaveToAnyTableFinisher
     20.class = In2code\Powermail\Finisher\SendParametersFinisher
     100.class = In2code\Powermail\Finisher\RedirectFinisher
diff --git a/Documentation/ForAdministrators/BestPractice/SpamPrevention.md b/Documentation/ForAdministrators/BestPractice/SpamPrevention.md
@@ -21,6 +21,8 @@ After a submit, different spammethods must be passed:
   a configured list of disallowed words.
 - **IP-Address Blacklist**: User IP address must not be on the list of
   disallowed addresses.
+- **Rate limiting**: User IP address may submit form only N times within a
+  time frame
 
 Every submitted form will be checked with this methods. Every failed
 method adds a Spam-Indication-Number to a storage. The sum of the
@@ -185,6 +187,38 @@ plugin.tx_powermail {
                         values.value = 123.132.125.123,123.132.125.124
                     }
                 }
+
+                # Rate limiter
+                8 {
+                    _enable = 1
+
+                    # Spamcheck name
+                    name = IP rate limiter
+
+                    # Class
+                    class = In2code\Powermail\Domain\Validator\SpamShield\RateLimitMethod
+
+                    # if this check fails - add this indication value to indicator (0 disables this check completely)
+                    indication = 100
+
+                    # method configuration
+                    configuration {
+                        #see "DateTimeInterval" class for allowed values
+                        interval = 5 minutes
+
+                        #number of form sumissions within the interval
+                        limit = 10
+
+                        # Parts of the rate limiting key
+                        # - placeholders: __ipAddress, __formIdentifier
+                        # - form values: {email}
+                        # - hard coded values: foo
+                        restrictions {
+                            10 = __ipAddress
+                            20 = __formIdentifier
+                        }
+                    }
+                }
             }
         }
     }
diff --git a/Documentation/ForDevelopers/AddFinisherClasses.md b/Documentation/ForDevelopers/AddFinisherClasses.md
@@ -169,4 +169,4 @@ class DoSomethingFinisher extends AbstractFinisher
 * The method `initializeFinisher()` will always be called at first.
 * Every finisher method could have its own initialize method, which will be called before. Like `initializeMyFinisher()` before `myFinisher()`.
 * Classes in extensions (if namespace and filename fits) will be automatically included from TYPO3 autoloader. If you place a single file in fileadmin, use "require" in TypoScript.
-* Per default 10, 20 and 100 is already in use from powermail itself (SaveToAnyTableFinisher, SendParametersFinisher, RedirectFinisher).
+* Per default 0, 10, 20 and 100 are already in use from powermail itself (RateLimitFinisher, SaveToAnyTableFinisher, SendParametersFinisher, RedirectFinisher).
diff --git a/composer.json b/composer.json
