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<?php |
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declare(strict_types=1); |
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namespace DanBettles\Defence\Filter; |
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use DanBettles\Defence\Envelope; |
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use InvalidArgumentException; |
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use Symfony\Component\HttpFoundation\Request; |
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use function array_flip; |
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use function array_intersect_key; |
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use function array_map; |
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use function array_replace; |
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use function gettype; |
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use function implode; |
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use function in_array; |
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use function is_array; |
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use function is_string; |
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use function preg_match; |
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use const false; |
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use const null; |
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use const true; |
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/** |
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* This filter can be used to reject requests containing a parameter with a suspicious value. Its principal purpose is |
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* to prevent SQL injection. |
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* |
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* There are a number of different types of parameter that can be easily vetted without in-depth knowledge of how |
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* they're used. For example, most -- if not all -- database ID (primary/foreign key) parameters, which are frequently |
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* targeted in SQL injection attacks, should contain only digits. Similarly, if you use the ISO 8601 format to express |
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* dates then you're expecting only digits and dashes. Consider the conventions you employ in your own application. |
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* |
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* There are two ways to select the parameters to examine: pass an array of names; or specify a regex that will match |
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* the names of parameters of interest. The second approach is especially useful if you follow strict naming |
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* conventions. For example, if you follow the old Ruby on Rails convention of using the suffixes "_on" and "_at" to |
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* indicate date/times then you could easily select date parameters. |
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* |
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* The validity of the value is determined using the 'validator', a regular expression that matches a _valid_ value. |
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* |
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* @phpstan-import-type IncomingFilterOptions from AbstractFilter |
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* |
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* @phpstan-type AugmentedFilterOptions array{log_level:string,type:string|null} |
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* @phpstan-type Selector string|string[] |
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* @phpstan-type RequestParameters array<string,string> |
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* @phpstan-type GroupedParameters array{query?:RequestParameters,request?:RequestParameters} |
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* |
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* @method AugmentedFilterOptions getOptions() |
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*/ |
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class InvalidParameterFilter extends AbstractFilter |
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{ |
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public const TYPE_ANY = null; |
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/** @var string */ |
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public const TYPE_STRING = 'string'; |
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/** @var string */ |
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public const TYPE_ARRAY = 'array'; |
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/** |
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* @var array<string|null> |
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*/ |
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private const VALID_TYPES = [ |
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self::TYPE_ANY, |
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self::TYPE_STRING, |
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self::TYPE_ARRAY, |
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]; |
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/** |
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* @phpstan-var Selector |
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*/ |
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private $selector; |
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/** |
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* @var string |
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*/ |
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private $validator; |
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/** |
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* @phpstan-param Selector $selector |
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* @phpstan-param IncomingFilterOptions $options |
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* @throws InvalidArgumentException If the value of the `type` option is invalid |
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*/ |
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public function __construct( |
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$selector, |
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string $validator, |
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array $options = [] |
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) { |
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/** @phpstan-var AugmentedFilterOptions */ |
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$completeOptions = array_replace([ |
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'type' => self::TYPE_ANY, |
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], $options); |
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parent::__construct($completeOptions); |
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$type = $this->getOptions()['type']; |
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if (!in_array($type, self::VALID_TYPES, true)) { |
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$listOfValidTypeNames = implode(', ', array_map( |
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fn ($typeName): string => (null === $typeName ? '`NULL`' : "`\"{$typeName}\"`"), |
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self::VALID_TYPES |
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)); |
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throw new InvalidArgumentException("Option `type` is not one of: {$listOfValidTypeNames}"); |
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} |
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$this |
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->setSelector($selector) |
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->setValidator($validator) |
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; |
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} |
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/** |
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* @phpstan-param Selector $selector |
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* @throws InvalidArgumentException If the selector is invalid. |
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*/ |
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private function setSelector($selector): self |
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{ |
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/** @phpstan-ignore-next-line */ |
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if (!is_array($selector) && !is_string($selector)) { |
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throw new InvalidArgumentException('The selector is invalid.'); |
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} |
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$this->selector = $selector; |
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return $this; |
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} |
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/** |
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* @phpstan-return Selector |
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*/ |
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public function getSelector() |
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{ |
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return $this->selector; |
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} |
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private function setValidator(string $validator): self |
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{ |
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$this->validator = $validator; |
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return $this; |
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} |
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public function getValidator(): string |
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{ |
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return $this->validator; |
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} |
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/** |
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* Returns an array containing all request parameters, grouped by parameter-bag name. |
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* |
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* @phpstan-return GroupedParameters |
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*/ |
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private function requestGetParametersGrouped(Request $request): array |
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{ |
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$grouped = []; |
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foreach (['query', 'request'] as $paramBagName) { |
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$grouped[$paramBagName] = $request->{$paramBagName}->all(); |
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} |
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return $grouped; |
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} |
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/** |
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* Filters the request parameters using the selector; returns an array containing the relevant request parameters |
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* grouped by parameter-bag name |
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* |
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* @phpstan-return GroupedParameters |
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*/ |
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private function filterRequestParametersBySelector(Request $request): array |
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{ |
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if (is_array($this->getSelector())) { |
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$selectorParamNamesAsKeys = array_flip($this->getSelector()); |
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$relevantParameters = []; |
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foreach ($this->requestGetParametersGrouped($request) as $paramBagName => $parameters) { |
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$relevantParameters[$paramBagName] = array_intersect_key($parameters, $selectorParamNamesAsKeys); |
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} |
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return $relevantParameters; |
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} |
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$relevantParameters = []; |
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foreach ($this->requestGetParametersGrouped($request) as $paramBagName => $parameters) { |
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foreach ($parameters as $paramName => $paramValue) { |
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if (preg_match($this->getSelector(), (string) $paramName)) { |
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$relevantParameters[$paramBagName][$paramName] = $paramValue; |
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} |
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} |
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} |
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return $relevantParameters; |
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} |
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/** |
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* Returns `true` if the parameter is valid, or `false` otherwise. Additionally, a message will be added to the |
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* log, accessed via the envelope, if the parameter is invalid. |
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*/ |
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private function validateParameterValue( |
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Envelope $envelope, |
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string $paramBagName, |
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string $paramName, |
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string $paramValue |
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): bool { |
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if (preg_match($this->getValidator(), $paramValue)) { |
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return true; |
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} |
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$this->envelopeAddLogEntry( |
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$envelope, |
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"The value of `{$paramBagName}.{$paramName}` failed validation using the regex `{$this->getValidator()}`." |
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); |
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return false; |
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} |
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public function __invoke(Envelope $envelope): bool |
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{ |
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$requiredType = $this->getOptions()['type']; |
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$filteredParamsByBagName = $this->filterRequestParametersBySelector($envelope->getRequest()); |
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foreach ($filteredParamsByBagName as $paramBagName => $parameters) { |
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foreach ($parameters as $paramName => $oneOrMoreValues) { |
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if (self::TYPE_ANY !== $requiredType && $requiredType !== gettype($oneOrMoreValues)) { |
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$this->envelopeAddLogEntry( |
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$envelope, |
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"The value of `{$paramBagName}.{$paramName}` is not of type `{$requiredType}`" |
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); |
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return true; |
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} |
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foreach ((array) $oneOrMoreValues as $paramValue) { |
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if (!$this->validateParameterValue($envelope, $paramBagName, $paramName, $paramValue)) { |
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return true; |
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} |
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} |
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} |
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} |
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return false; |
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} |
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} |
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