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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_Header object definition {{{ */
/**
* Object representation of the HEADER section of a DNS packet
*
* The Net_DNS::Header class contains the values of a DNS packet. It parses
* the header of a DNS packet or can generate the binary data
* representation of the packet. The format of the header is described in
* RFC1035.
*
* @package Net_DNS
*/
class Net_DNS_Header
{
/* class variable definitions {{{ */
/**
* The packet's request id
*
* The request id of the packet represented as a 16 bit integer.
*/
var $id;
/**
* The QR bit in a DNS packet header
*
* The QR bit as described in RFC1035. QR is set to 0 for queries, and
* 1 for repsones.
*/
var $qr;
/**
* The OPCODE name of this packet.
*
* The string value (name) of the opcode for the DNS packet.
*/
var $opcode;
/**
* The AA (authoritative answer) bit in a DNS packet header
*
* The AA bit as described in RFC1035. AA is set to 1 if the answer
* is authoritative. It has no meaning if QR is set to 0.
*/
var $aa;
/**
* The TC (truncated) bit in a DNS packet header
*
* This flag is set to 1 if the response was truncated. This flag has
* no meaning in a query packet.
*/
var $tc;
/**
* The RD (recursion desired) bit in a DNS packet header
*
* This bit should be set to 1 in a query if recursion is desired by
* the DNS server.
*/
var $rd;
/**
* The RA (recursion available) bit in a DNS packet header
*
* This bit is set to 1 by the DNS server if the server is willing to
* perform recursion.
*/
var $ra;
/**
* The RCODE name for this packet.
*
* The string value (name) of the rcode for the DNS packet.
*/
var $rcode;
/**
* Number of questions contained within the packet
*
* 16bit integer representing the number of questions in the question
* section of the DNS packet.
*
* @var integer $qdcount
* @see Net_DNS_Question class
*/
var $qdcount;
/**
* Number of answer RRs contained within the packet
*
* 16bit integer representing the number of answer resource records
* contained in the answer section of the DNS packet.
*
* @var integer $ancount
* @see Net_DNS_RR class
*/
var $ancount;
/**
* Number of authority RRs within the packet
*
* 16bit integer representing the number of authority (NS) resource
* records contained in the authority section of the DNS packet.
*
* @var integer $nscount
* @see Net_DNS_RR class
*/
var $nscount;
/**
* Number of additional RRs within the packet
*
* 16bit integer representing the number of additional resource records
* contained in the additional section of the DNS packet.
*
* @var integer $arcount
* @see Net_DNS_RR class
*/
var $arcount;
/* }}} */
/* class constructor - Net_DNS_Header($data = "") {{{ */
/**
* Initializes the default values for the Header object.
*
* Builds a header object from either default values, or from a DNS
* packet passed into the constructor as $data
*
* @param string $data A DNS packet of which the header will be parsed.
* @return object Net_DNS_Header
* @access public
*/
function Net_DNS_Header($data = '')
{
if ($data != '') {
/*
* The header MUST be at least 12 bytes.
* Passing the full datagram to this constructor
* will examine only the header section of the DNS packet
*/
if (strlen($data) < 12)
return false;
$a = unpack('nid/C2flags/n4counts', $data);
$this->id = $a['id'];
$this->qr = ($a['flags1'] >> 7) & 0x1;
$this->opcode = ($a['flags1'] >> 3) & 0xf;
$this->aa = ($a['flags1'] >> 2) & 0x1;
$this->tc = ($a['flags1'] >> 1) & 0x1;
$this->rd = $a['flags1'] & 0x1;
$this->ra = ($a['flags2'] >> 7) & 0x1;
$this->rcode = $a['flags2'] & 0xf;
$this->qdcount = $a['counts1'];
$this->ancount = $a['counts2'];
$this->nscount = $a['counts3'];
$this->arcount = $a['counts4'];
}
else {
$this->id = Net_DNS_Resolver::nextid();
$this->qr = 0;
$this->opcode = 0;
$this->aa = 0;
$this->tc = 0;
$this->rd = 1;
$this->ra = 0;
$this->rcode = 0;
$this->qdcount = 1;
$this->ancount = 0;
$this->nscount = 0;
$this->arcount = 0;
}
if (Net_DNS::opcodesbyval($this->opcode)) {
$this->opcode = Net_DNS::opcodesbyval($this->opcode);
}
if (Net_DNS::rcodesbyval($this->rcode)) {
$this->rcode = Net_DNS::rcodesbyval($this->rcode);
}
}
/* }}} */
/* Net_DNS_Header::display() {{{ */
/**
* Displays the properties of the header.
*
* Displays the properties of the header.
*
* @access public
*/
function display()
{
echo $this->string();
}
/* }}} */
/* Net_DNS_Header::string() {{{ */
/**
* Returns a formatted string containing the properties of the header.
*
* @return string a formatted string containing the properties of the header.
* @access public
*/
function string()
{
$retval = ';; id = ' . $this->id . "\n";
if ($this->opcode == 'UPDATE') {
$retval .= ';; qr = ' . $this->qr . ' ' .
'opcode = ' . $this->opcode . ' ' .
'rcode = ' . $this->rcode . "\n";
$retval .= ';; zocount = ' . $this->qdcount . ' ' .
'prcount = ' . $this->ancount . ' ' .
'upcount = ' . $this->nscount . ' ' .
'adcount = ' . $this->arcount . "\n";
} else {
$retval .= ';; qr = ' . $this->qr . ' ' .
'opcode = ' . $this->opcode . ' ' .
'aa = ' . $this->aa . ' ' .
'tc = ' . $this->tc . ' ' .
'rd = ' . $this->rd . "\n";
$retval .= ';; ra = ' . $this->ra . ' ' .
'rcode = ' . $this->rcode . "\n";
$retval .= ';; qdcount = ' . $this->qdcount . ' ' .
'ancount = ' . $this->ancount . ' ' .
'nscount = ' . $this->nscount . ' ' .
'arcount = ' . $this->arcount . "\n";
}
return $retval;
}
/* }}} */
/* Net_DNS_Header::data() {{{ */
/**
* Returns the binary data containing the properties of the header
*
* Packs the properties of the Header object into a binary string
* suitable for using as the Header section of a DNS packet.
*
* @return string binary representation of the header object
* @access public
*/
function data()
{
$opcode = Net_DNS::opcodesbyname($this->opcode);
$rcode = Net_DNS::rcodesbyname($this->rcode);
$byte2 = ($this->qr << 7)
| ($opcode << 3)
| ($this->aa << 2)
| ($this->tc << 1)
| ($this->rd);
$byte3 = ($this->ra << 7) | $rcode;
return pack('nC2n4', $this->id,
$byte2,
$byte3,
$this->qdcount,
$this->ancount,
$this->nscount,
$this->arcount);
}
/* }}} */
}
/* }}} */
/* VIM settings {{{
* Local variables:
* tab-width: 4
* c-basic-offset: 4
* soft-stop-width: 4
* c indent on
* expandtab on
* End:
* vim600: sw=4 ts=4 sts=4 cindent fdm=marker et
* vim<600: sw=4 ts=4
* }}} */
?>
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