true, "content-encoding" => true, "content-length" => true, "content-range" => true, "content-type" => true, "cookie" => true, "expect" => true, "host" => true, "pragma" => true, "proxy-authenticate" => true, "proxy-authorization" => true, "range" => true, "te" => true, "trailer" => true, "transfer-encoding" => true, "www-authenticate" => true, ]; /** @var list */ private readonly array $fields; /** @var Future */ private readonly Future $messageFuture; /** * @param Future>> $future Resolved with the trailer values. * @param string[] $fields Expected header fields. May be empty, but if provided, the array of * headers used to complete the given future must contain exactly the fields given in this array. * * @throws InvalidHeaderException If the fields list contains a disallowed field. */ public function __construct(Future $future, array $fields = []) { $this->fields = $fields = \array_map('strtolower', \array_values($fields)); foreach ($this->fields as $field) { if (isset(self::DISALLOWED_TRAILERS[$field])) { throw new InvalidHeaderException(\sprintf("Field '%s' is not allowed in trailers", $field)); } } $this->messageFuture = async(static function () use ($future, $fields): HttpMessage { return new class($future->await(), $fields) extends HttpMessage { public function __construct(array $headers, array $fields) { $this->setHeaders($headers); $keys = \array_keys($this->getHeaders()); if (!empty($fields)) { // Note that the Trailer header does not need to be set for the message to include trailers. // @see https://tools.ietf.org/html/rfc7230#section-4.4 if (\array_diff($fields, $keys)) { throw new InvalidHeaderException("Trailers do not contain the expected fields"); } return; // Check below unnecessary if fields list is set. } foreach ($keys as $field) { if (isset(Trailers::DISALLOWED_TRAILERS[$field])) { throw new InvalidHeaderException(\sprintf("Field '%s' is not allowed in trailers", $field)); } } } }; }); // Future may fail due to client disconnect or error, but we don't want to force awaiting. $this->messageFuture->ignore(); } /** * @return list List of expected trailer fields. May be empty, but still receive trailers. */ public function getFields(): array { return $this->fields; } public function await(?Cancellation $cancellation = null): HttpMessage { return $this->messageFuture->await($cancellation); } }