/**
* Encode the header section of the message
*
* @param \LibDNS\Encoder\EncodingContext $encodingContext
* @param \LibDNS\Messages\Message $message
* @return string
* @throws \UnexpectedValueException When the header section is invalid
*/
private function encodeHeader(EncodingContext $encodingContext, Message $message)
{
$header = ['id' => $message->getID(), 'meta' => 0, 'qd' => $message->getQuestionRecords()->count(), 'an' => $message->getAnswerRecords()->count(), 'ns' => $message->getAuthorityRecords()->count(), 'ar' => $message->getAdditionalRecords()->count()];
$header['meta'] |= $message->getType() << 16;
$header['meta'] |= $message->getOpCode() << 11;
$header['meta'] |= (int) $message->isAuthoritative() << 10;
$header['meta'] |= (int) $encodingContext->isTruncated() << 9;
$header['meta'] |= (int) $message->isRecursionDesired() << 8;
$header['meta'] |= (int) $message->isRecursionAvailable() << 7;
$header['meta'] |= $message->getResponseCode();
return pack('n*', $header['id'], $header['meta'], $header['qd'], $header['an'], $header['ns'], $header['ar']);
}
/**
* Decode the header section of the message
*
* @param \LibDNS\Decoder\DecodingContext $decodingContext
* @param \LibDNS\Messages\Message $message
* @throws \UnexpectedValueException When the header section is invalid
*/
private function decodeHeader(DecodingContext $decodingContext, Message $message)
{
$header = unpack('nid/nmeta/nqd/nan/nns/nar', $this->readDataFromPacket($decodingContext->getPacket(), 12));
if (!$header) {
throw new \UnexpectedValueException('Decode error: Header unpack failed');
}
$message->setID($header['id']);
$message->setType(($header['meta'] & 0b1000000000000000) >> 15);
$message->setOpCode(($header['meta'] & 0b111100000000000) >> 11);
$message->isAuthoritative(($header['meta'] & 0b10000000000) >> 10);
$message->isTruncated(($header['meta'] & 0b1000000000) >> 9);
$message->isRecursionDesired(($header['meta'] & 0b100000000) >> 8);
$message->isRecursionAvailable(($header['meta'] & 0b10000000) >> 7);
$message->setResponseCode($header['meta'] & 0b1111);
$decodingContext->setExpectedQuestionRecords($header['qd']);
$decodingContext->setExpectedAnswerRecords($header['an']);
$decodingContext->setExpectedAuthorityRecords($header['ns']);
$decodingContext->setExpectedAdditionalRecords($header['ar']);
}
