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<?php
/*
* License Information:
*
* Net_DNS: A resolver library for PHP
* Copyright (c) 2002-2003 Eric Kilfoil eric@ypass.net
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/* Net_DNS_Packet object definition {{{ */
/**
* A object represation of a DNS packet (RFC1035)
*
* This object is used to manage a DNS packet. It contains methods for
* DNS packet compression as defined in RFC1035, as well as parsing a DNS
* packet response from a DNS server, or building a DNS packet from the
* instance variables contained in the class.
*
* @package Net_DNS
*/
class Net_DNS_Packet
{
/* class variable definitions {{{ */
/**
* debugging flag
*
* If set to true (non-zero), debugging code will be displayed as the
* packet is parsed.
*
* @var boolean $debug
* @access public
*/
var $debug;
/**
* A packet Header object.
*
* An object of type Net_DNS_Header which contains the header
* information of the packet.
*
* @var object Net_DNS_Header $header
* @access public
*/
var $header;
/**
* A hash of compressed labels
*
* A list of all labels which have been compressed in the DNS packet
* and the location offset of the label within the packet.
*
* @var array $compnames
*/
var $compnames;
/**
* The origin of the packet, if the packet is a server response.
*
* This contains a string containing the IP address of the name server
* from which the answer was given.
*
* @var string $answerfrom
* @access public
*/
var $answerfrom;
/**
* The size of the answer packet, if the packet is a server response.
*
* This contains a integer containing the size of the DNS packet the
* server responded with if this packet was received by a DNS server
* using the query() method.
*
* @var string $answersize
* @access public
*/
var $answersize;
/**
* An array of Net_DNS_Question objects
*
* Contains all of the questions within the packet. Each question is
* stored as an object of type Net_DNS_Question.
*
* @var array $question
* @access public
*/
var $question;
/**
* An array of Net_DNS_RR ANSWER objects
*
* Contains all of the answer RRs within the packet. Each answer is
* stored as an object of type Net_DNS_RR.
*
* @var array $answer
* @access public
*/
var $answer;
/**
* An array of Net_DNS_RR AUTHORITY objects
*
* Contains all of the authority RRs within the packet. Each authority is
* stored as an object of type Net_DNS_RR.
*
* @var array $authority
* @access public
*/
var $authority;
/**
* An array of Net_DNS_RR ADDITIONAL objects
*
* Contains all of the additional RRs within the packet. Each additional is
* stored as an object of type Net_DNS_RR.
*
* @var array $additional
* @access public
*/
var $additional;
/* }}} */
/* class constructor - Net_DNS_Packet($debug = false) {{{ */
/*
* unfortunately (or fortunately), we can't follow the same
* silly method for determining if name is a hostname or a packet
* stream in PHP, since there is no ref() function. So we're going
* to define a new method called parse to deal with this
* circumstance and another method called buildQuestion to build a question.
* I like it better that way anyway.
*/
/**
* Initalizes a Net_DNS_Packet object
*
* @param boolean $debug Turns debugging on or off
*/
function Net_DNS_Packet($debug = false)
{
$this->debug = $debug;
$this->compnames = array();
}
/* }}} */
/* Net_DNS_Packet::buildQuestion($name, $type = "A", $class = "IN") {{{ */
/**
* Adds a DNS question to the DNS packet
*
* @param string $name The name of the record to query
* @param string $type The type of record to query
* @param string $class The class of record to query
* @see Net_DNS::typesbyname(), Net_DNS::classesbyname()
*/
function buildQuestion($name, $type = 'A', $class = 'IN')
{
$this->header = new Net_DNS_Header();
$this->header->qdcount = 1;
$this->question[0] = new Net_DNS_Question($name, $type, $class);
$this->answer = null;
$this->authority = null;
$this->additional = null;
/* Do not print question packet
if ($this->debug) {
$this->display();
}
*/
}
/* }}} */
/* Net_DNS_Packet::parse($data) {{{ */
/**
* Parses a DNS packet returned by a DNS server
*
* Parses a complete DNS packet and builds an object hierarchy
* containing all of the parts of the packet:
* <ul>
* <li>HEADER
* <li>QUESTION
* <li>ANSWER || PREREQUISITE
* <li>ADDITIONAL || UPDATE
* <li>AUTHORITY
* </ul>
*
* @param string $data A binary string containing a DNS packet
* @return boolean true on success, null on parser error
*/
function parse($data)
{
if ($this->debug) {
echo ';; HEADER SECTION' . "\n";
}
$this->header = new Net_DNS_Header($data);
if ($this->debug) {
$this->header->display();
}
/*
* Print and parse the QUESTION section of the packet
*/
if ($this->debug) {
echo "\n";
$section = ($this->header->opcode == 'UPDATE') ? 'ZONE' : 'QUESTION';
echo ";; $section SECTION (" . $this->header->qdcount . ' record' .
($this->header->qdcount == 1 ? '' : 's') . ")\n";
}
$offset = 12;
$this->question = array();
for ($ctr = 0; $ctr < $this->header->qdcount; $ctr++) {
list($qobj, $offset) = $this->parse_question($data, $offset);
if (is_null($qobj)) {
return null;
}
$this->question[count($this->question)] = $qobj;
if ($this->debug) {
echo ";;\n;";
$qobj->display();
}
}
/*
* Print and parse the PREREQUISITE or ANSWER section of the packet
*/
if ($this->debug) {
echo "\n";
$section = ($this->header->opcode == 'UPDATE') ? 'PREREQUISITE' :'ANSWER';
echo ";; $section SECTION (" .
$this->header->ancount . ' record' .
(($this->header->ancount == 1) ? '' : 's') .
")\n";
}
$this->answer = array();
for ($ctr = 0; $ctr < $this->header->ancount; $ctr++) {
list($rrobj, $offset) = $this->parse_rr($data, $offset);
if (is_null($rrobj)) {
return null;
}
array_push($this->answer, $rrobj);
if ($this->debug) {
$rrobj->display();
}
}
/*
* Print and parse the UPDATE or AUTHORITY section of the packet
*/
if ($this->debug) {
echo "\n";
$section = ($this->header->opcode == 'UPDATE') ? 'UPDATE' : 'AUTHORITY';
echo ";; $section SECTION (" .
$this->header->nscount . ' record' .
(($this->header->nscount == 1) ? '' : 's') .
")\n";
}
$this->authority = array();
for ($ctr = 0; $ctr < $this->header->nscount; $ctr++) {
list($rrobj, $offset) = $this->parse_rr($data, $offset);
if (is_null($rrobj)) {
return null;
}
array_push($this->authority, $rrobj);
if ($this->debug) {
$rrobj->display();
}
}
/*
* Print and parse the ADDITIONAL section of the packet
*/
if ($this->debug) {
echo "\n";
echo ';; ADDITIONAL SECTION (' .
$this->header->arcount . ' record' .
(($this->header->arcount == 1) ? '' : 's') .
")\n";
}
$this->additional = array();
for ($ctr = 0; $ctr < $this->header->arcount; $ctr++) {
list($rrobj, $offset) = $this->parse_rr($data, $offset);
if (is_null($rrobj)) {
return null;
}
array_push($this->additional, $rrobj);
if ($this->debug) {
$rrobj->display();
}
}
return true;
}
/* }}} */
/* Net_DNS_Packet::data() {{{*/
/**
* Build a packet from a Packet object hierarchy
*
* Builds a valid DNS packet suitable for sending to a DNS server or
* resolver client containing all of the data in the packet hierarchy.
*
* @return string A binary string containing a DNS Packet
*/
function data()
{
$data = $this->header->data();
for ($ctr = 0; $ctr < $this->header->qdcount; $ctr++) {
$data .= $this->question[$ctr]->data($this, strlen($data));
}
for ($ctr = 0; $ctr < $this->header->ancount; $ctr++) {
$data .= $this->answer[$ctr]->data($this, strlen($data));
}
for ($ctr = 0; $ctr < $this->header->nscount; $ctr++) {
$data .= $this->authority[$ctr]->data($this, strlen($data));
}
for ($ctr = 0; $ctr < $this->header->arcount; $ctr++) {
$data .= $this->additional[$ctr]->data($this, strlen($data));
}
return $data;
}
/*}}}*/
/* Net_DNS_Packet::dn_comp($name, $offset) {{{*/
/**
* DNS packet compression method
*
* Returns a domain name compressed for a particular packet object, to
* be stored beginning at the given offset within the packet data. The
* name will be added to a running list of compressed domain names for
* future use.
*
* @param string $name The name of the label to compress
* @param integer $offset The location offset in the packet to where
* the label will be stored.
* @return string $compname A binary string containing the compressed
* label.
* @see Net_DNS_Packet::dn_expand()
*/
function dn_comp($name, $offset)
{
$names = explode('.', $name);
$compname = '';
while (count($names)) {
$dname = join('.', $names);
if (isset($this->compnames[$dname])) {
$compname .= pack('n', 0xc000 | $this->compnames[$dname]);
break;
}
$this->compnames[$dname] = $offset;
$first = array_shift($names);
$length = strlen($first);
$compname .= pack('Ca*', $length, $first);
$offset += $length + 1;
}
if (! count($names)) {
$compname .= pack('C', 0);
}
return $compname;
}
/*}}}*/
/* Net_DNS_Packet::dn_expand($packet, $offset) {{{ */
/**
* DNS packet decompression method
*
* Expands the domain name stored at a particular location in a DNS
* packet. The first argument is a variable containing the packet
* data. The second argument is the offset within the packet where
* the (possibly) compressed domain name is stored.
*
* @param string $packet The packet data
* @param integer $offset The location offset in the packet of the
* label to decompress.
* @return array Returns a list of type array($name, $offset) where
* $name is the name of the label which was decompressed
* and $offset is the offset of the next field in the
* packet. Returns array(null, null) on error
*/
function dn_expand($packet, $offset)
{
$packetlen = strlen($packet);
$int16sz = 2;
$name = '';
while (1) {
if ($packetlen < ($offset + 1)) {
return array(null, null);
}
$a = unpack("@$offset/Cchar", $packet);
$len = $a['char'];
if ($len == 0) {
$offset++;
break;
} else if (($len & 0xc0) == 0xc0) {
if ($packetlen < ($offset + $int16sz)) {
return array(null, null);
}
$ptr = unpack("@$offset/ni", $packet);
$ptr = $ptr['i'];
$ptr = $ptr & 0x3fff;
$name2 = Net_DNS_Packet::dn_expand($packet, $ptr);
if (is_null($name2[0])) {
return array(null, null);
}
$name .= $name2[0];
$offset += $int16sz;
break;
} else {
$offset++;
if ($packetlen < ($offset + $len)) {
return array(null, null);
}
$elem = substr($packet, $offset, $len);
$name .= $elem . '.';
$offset += $len;
}
}
$name = ereg_replace('\.$', '', $name);
return array($name, $offset);
}
/*}}}*/
/* Net_DNS_Packet::label_extract($packet, $offset) {{{ */
/**
* DNS packet decompression method
*
* Extracts the label stored at a particular location in a DNS
* packet. The first argument is a variable containing the packet
* data. The second argument is the offset within the packet where
* the (possibly) compressed domain name is stored.
*
* @param string $packet The packet data
* @param integer $offset The location offset in the packet of the
* label to extract.
* @return array Returns a list of type array($name, $offset) where
* $name is the name of the label which was decompressed
* and $offset is the offset of the next field in the
* packet. Returns array(null, null) on error
*/
function label_extract($packet, $offset)
{
$packetlen = strlen($packet);
$name = '';
if ($packetlen < ($offset + 1)) {
return array(null, null);
}
$a = unpack("@$offset/Cchar", $packet);
$len = $a['char'];
$offset++;
if ($len + $offset > $packetlen) {
$name = substr($packet, $offset);
$offset = $packetlen;
} else {
$name = substr($packet, $offset, $len);
$offset += $len;
}
return array($name, $offset);
}
/*}}}*/
/* Net_DNS_Packet::parse_question($data, $offset) {{{ */
/**
* Parses the question section of a packet
*
* Examines a DNS packet at the specified offset and parses the data
* of the QUESTION section.
*
* @param string $data The packet data returned from the server
* @param integer $offset The location offset of the start of the
* question section.
* @return array An array of type array($q, $offset) where $q
* is a Net_DNS_Question object and $offset is the
* location of the next section of the packet which
* needs to be parsed.
*/
function parse_question($data, $offset)
{
list($qname, $offset) = $this->dn_expand($data, $offset);
if (is_null($qname)) {
return array(null, null);
}
if (strlen($data) < ($offset + 2 * 2)) {
return array(null, null);
}
$q = unpack("@$offset/n2int", $data);
$qtype = $q['int1'];
$qclass = $q['int2'];
$offset += 2 * 2;
$qtype = Net_DNS::typesbyval($qtype);
$qclass = Net_DNS::classesbyval($qclass);
$q = new Net_DNS_Question($qname, $qtype, $qclass);
return array($q, $offset);
}
/*}}}*/
/* Net_DNS_Packet::parse_rr($data, $offset) {{{ */
/**
* Parses a resource record section of a packet
*
* Examines a DNS packet at the specified offset and parses the data
* of a section which contains RRs (ANSWER, AUTHORITY, ADDITIONAL).
*
* @param string $data The packet data returned from the server
* @param integer $offset The location offset of the start of the resource
* record section.
* @return array An array of type array($rr, $offset) where $rr
* is a Net_DNS_RR object and $offset is the
* location of the next section of the packet which
* needs to be parsed.
*/
function parse_rr($data, $offset)
{
list($name, $offset) = $this->dn_expand($data, $offset);
if ($name === null) {
return array(null, null);
}
if (strlen($data) < ($offset + 10)) {
return array(null, null);
}
$a = unpack("@$offset/n2tc/Nttl/nrdlength", $data);
$type = $a['tc1'];
$class = $a['tc2'];
$ttl = $a['ttl'];
$rdlength = $a['rdlength'];
$type = Net_DNS::typesbyval($type);
$class = Net_DNS::classesbyval($class);
$offset += 10;
if (strlen($data) < ($offset + $rdlength)) {
return array(null, null);
}
$rrobj = &Net_DNS_RR::factory(array($name,
$type,
$class,
$ttl,
$rdlength,
$data,
$offset));
if (is_null($rrobj)) {
return array(null, null);
}
$offset += $rdlength;
return array($rrobj, $offset);
}
/* }}} */
/* Net_DNS_Packet::display() {{{ */
/**
* Prints out the packet in a human readable formatted string
*/
function display()
{
echo $this->string();
}
/*}}}*/
/* Net_DNS_Packet::string() {{{ */
/**
* Builds a human readable formatted string representing a packet
*/
function string()
{
$retval = '';
if ($this->answerfrom) {
$retval .= ';; Answer received from ' . $this->answerfrom . '(' .
$this->answersize . " bytes)\n;;\n";
}
$retval .= ";; HEADER SECTION\n";
$retval .= $this->header->string();
$retval .= "\n";
$section = ($this->header->opcode == 'UPDATE') ? 'ZONE' : 'QUESTION';
$retval .= ";; $section SECTION (" . $this->header->qdcount .
' record' . ($this->header->qdcount == 1 ? '' : 's') .
")\n";
foreach ($this->question as $qr) {
$retval .= ';; ' . $qr->string() . "\n";
}
$section = ($this->header->opcode == 'UPDATE') ? 'PREREQUISITE' : 'ANSWER';
$retval .= "\n;; $section SECTION (" . $this->header->ancount .
' record' . ($this->header->ancount == 1 ? '' : 's') .
")\n";
if (is_array($this->answer)) {
foreach ($this->answer as $ans) {
$retval .= ';; ' . $ans->string() . "\n";
}
}
$section = ($this->header->opcode == 'UPDATE') ? 'UPDATE' : 'AUTHORITY';
$retval .= "\n;; $section SECTION (" . $this->header->nscount .
' record' . ($this->header->nscount == 1 ? '' : 's') .
")\n";
if (is_array($this->authority)) {
foreach ($this->authority as $auth) {
$retval .= ';; ' . $auth->string() . "\n";
}
}
$retval .= "\n;; ADDITIONAL SECTION (" . $this->header->arcount .
' record' . ($this->header->arcount == 1 ? '' : 's') .
")\n";
if (is_array($this->additional)) {
foreach ($this->additional as $addl) {
$retval .= ';; ' . $addl->string() . "\n";
}
}
$retval .= "\n\n";
return $retval;
}
/*}}}*/
}
/* }}} */
/* VIM settings {{{
* Local variables:
* tab-width: 4
* c-basic-offset: 4
* soft-stop-width: 4
* c indent on
* End:
* vim600: sw=4 ts=4 sts=4 cindent fdm=marker et
* vim<600: sw=4 ts=4
* }}} */
?>
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