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|
<?php
namespace React\Dns\Protocol;
use React\Dns\Model\Message;
use React\Dns\Model\Record;
use InvalidArgumentException;
/**
* DNS protocol parser
*
* Obsolete and uncommon types and classes are not implemented.
*/
class Parser
{
/**
* Parses the given raw binary message into a Message object
*
* @param string $data
* @throws InvalidArgumentException
* @return Message
*/
public function parseMessage($data)
{
$message = new Message();
if ($this->parse($data, $message) !== $message) {
throw new InvalidArgumentException('Unable to parse binary message');
}
return $message;
}
/**
* @deprecated unused, exists for BC only
*/
public function parseChunk($data, Message $message)
{
return $this->parse($data, $message);
}
private function parse($data, Message $message)
{
$message->data .= $data;
if (!$message->header->get('id')) {
if (!$this->parseHeader($message)) {
return;
}
}
if ($message->header->get('qdCount') != count($message->questions)) {
if (!$this->parseQuestion($message)) {
return;
}
}
if ($message->header->get('anCount') != count($message->answers)) {
if (!$this->parseAnswer($message)) {
return;
}
}
return $message;
}
public function parseHeader(Message $message)
{
if (strlen($message->data) < 12) {
return;
}
$header = substr($message->data, 0, 12);
$message->consumed += 12;
list($id, $fields, $qdCount, $anCount, $nsCount, $arCount) = array_values(unpack('n*', $header));
$rcode = $fields & bindec('1111');
$z = ($fields >> 4) & bindec('111');
$ra = ($fields >> 7) & 1;
$rd = ($fields >> 8) & 1;
$tc = ($fields >> 9) & 1;
$aa = ($fields >> 10) & 1;
$opcode = ($fields >> 11) & bindec('1111');
$qr = ($fields >> 15) & 1;
$vars = compact('id', 'qdCount', 'anCount', 'nsCount', 'arCount',
'qr', 'opcode', 'aa', 'tc', 'rd', 'ra', 'z', 'rcode');
foreach ($vars as $name => $value) {
$message->header->set($name, $value);
}
return $message;
}
public function parseQuestion(Message $message)
{
if (strlen($message->data) < 2) {
return;
}
$consumed = $message->consumed;
list($labels, $consumed) = $this->readLabels($message->data, $consumed);
if (null === $labels) {
return;
}
if (strlen($message->data) - $consumed < 4) {
return;
}
list($type, $class) = array_values(unpack('n*', substr($message->data, $consumed, 4)));
$consumed += 4;
$message->consumed = $consumed;
$message->questions[] = array(
'name' => implode('.', $labels),
'type' => $type,
'class' => $class,
);
if ($message->header->get('qdCount') != count($message->questions)) {
return $this->parseQuestion($message);
}
return $message;
}
public function parseAnswer(Message $message)
{
if (strlen($message->data) < 2) {
return;
}
$consumed = $message->consumed;
list($labels, $consumed) = $this->readLabels($message->data, $consumed);
if (null === $labels) {
return;
}
if (strlen($message->data) - $consumed < 10) {
return;
}
list($type, $class) = array_values(unpack('n*', substr($message->data, $consumed, 4)));
$consumed += 4;
list($ttl) = array_values(unpack('N', substr($message->data, $consumed, 4)));
$consumed += 4;
list($rdLength) = array_values(unpack('n', substr($message->data, $consumed, 2)));
$consumed += 2;
$rdata = null;
if (Message::TYPE_A === $type || Message::TYPE_AAAA === $type) {
$ip = substr($message->data, $consumed, $rdLength);
$consumed += $rdLength;
$rdata = inet_ntop($ip);
}
if (Message::TYPE_CNAME === $type || Message::TYPE_PTR === $type) {
list($bodyLabels, $consumed) = $this->readLabels($message->data, $consumed);
$rdata = implode('.', $bodyLabels);
}
$message->consumed = $consumed;
$name = implode('.', $labels);
$ttl = $this->signedLongToUnsignedLong($ttl);
$record = new Record($name, $type, $class, $ttl, $rdata);
$message->answers[] = $record;
if ($message->header->get('anCount') != count($message->answers)) {
return $this->parseAnswer($message);
}
return $message;
}
private function readLabels($data, $consumed)
{
$labels = array();
while (true) {
if ($this->isEndOfLabels($data, $consumed)) {
$consumed += 1;
break;
}
if ($this->isCompressedLabel($data, $consumed)) {
list($newLabels, $consumed) = $this->getCompressedLabel($data, $consumed);
$labels = array_merge($labels, $newLabels);
break;
}
$length = ord(substr($data, $consumed, 1));
$consumed += 1;
if (strlen($data) - $consumed < $length) {
return array(null, null);
}
$labels[] = substr($data, $consumed, $length);
$consumed += $length;
}
return array($labels, $consumed);
}
public function isEndOfLabels($data, $consumed)
{
$length = ord(substr($data, $consumed, 1));
return 0 === $length;
}
public function getCompressedLabel($data, $consumed)
{
list($nameOffset, $consumed) = $this->getCompressedLabelOffset($data, $consumed);
list($labels) = $this->readLabels($data, $nameOffset);
return array($labels, $consumed);
}
public function isCompressedLabel($data, $consumed)
{
$mask = 0xc000; // 1100000000000000
list($peek) = array_values(unpack('n', substr($data, $consumed, 2)));
return (bool) ($peek & $mask);
}
public function getCompressedLabelOffset($data, $consumed)
{
$mask = 0x3fff; // 0011111111111111
list($peek) = array_values(unpack('n', substr($data, $consumed, 2)));
return array($peek & $mask, $consumed + 2);
}
public function signedLongToUnsignedLong($i)
{
return $i & 0x80000000 ? $i - 0xffffffff : $i;
}
}
|
