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lib::Net::DNS::Packet

Section: User Contributed Perl Documentation (3)
Updated: perl 5.004, patch 04
Index

NAME

Net::DNS::Packet - DNS packet object class

SYNOPSIS

use Net::DNS::Packet;

DESCRIPTION

A Net::DNS::Packet object represents a DNS packet.

METHODS

new

    $packet = new Net::DNS::Packet(\$data);    $packet = new Net::DNS::Packet(\$data, 1);  # set debugging

    $packet = new Net::DNS::Packet("foo.com");    $packet = new Net::DNS::Packet("foo.com", "MX", "IN");

    ($packet, $err) = new Net::DNS::Packet(\$data);

If passed a reference to a scalar containing DNS packet data,new creates a packet object from that data. A second argumentcan be passed to turn on debugging output for packet parsing.

If passed a domain, type, and class, new creates a packetobject appropriate for making a DNS query for the requestedinformation. The type and class can be omitted; they defaultto A and IN.

If called in array context, returns a packet object and anerror string. The error string will only be defined if thepacket object is undefined (i.e., couldn't be created).

Returns undef if unable to create a packet object (e.g., ifthe packet data is truncated).

data

    $data = $packet->data;

Returns the packet data in binary format, suitable for sending toa nameserver.

header

    $header = $packet->header;

Returns a Net::DNS::Header object representing the header sectionof the packet.

question, zone

    @question = $packet->question;

Returns a list of Net::DNS::Question objects representing thequestion section of the packet.

In dynamic update packets, this section is known as zone andspecifies the zone to be updated.

answer, pre, prerequisite

    @answer = $packet->answer;

Returns a list of Net::DNS::RR objects representing the answersection of the packet.

In dynamic update packets, this section is known as pre orprerequisite and specifies the RRs or RRsets which must ormust not preexist.

authority, update

    @authority = $packet->authority;

Returns a list of Net::DNS::RR objects representing the authoritysection of the packet.

In dynamic update packets, this section is known as update andspecifies the RRs or RRsets to be added or delted.

additional

    @additional = $packet->additional;

Returns a list of Net::DNS::RR objects representing the additionalsection of the packet.

print

    $packet->print;

Prints the packet data on the standard output in an ASCII formatsimilar to that used in DNS zone files.

string

    print $packet->string;

Returns a string representation of the packet.

answerfrom

    print "packet received from ", $packet->answerfrom, "\n";

Returns the IP address from which we received this packet. User-createdpackets will return undef for this method.

answersize

    print "packet size: ", $packet->answersize, " bytes\n";

Returns the size of the packet in bytes as it was received from anameserver. User-created packets will return undef for this method(use length $packet->data instead).

push

    $packet->push("pre", $rr);    $packet->push("update", $rr);    $packet->push("additional", $rr);

    $packet->push("update", $rr1, $rr2, $rr3);    $packet->push("update", @rr);

Adds RRs to the specified section of the packet.

dn_comp

    $compname = $packet->dn_comp("foo.bar.com", $offset);

Returns a domain name compressed for a particular packet object, tobe stored beginning at the given offset within the packet data. Thename will be added to a running list of compressed domain names forfuture use.

dn_expand

    use Net::DNS::Packet qw(dn_expand);    ($name, $nextoffset) = dn_expand(\$data, $offset);

    ($name, $nextoffset) = Net::DNS::Packet::dn_expand(\$data, $offset);

Expands the domain name stored at a particular location in a DNSpacket. The first argument is a reference to a scalar containingthe packet data. The second argument is the offset within thepacket where the (possibly compressed) domain name is stored.

Returns the domain name and the offset of the next location in thepacket.

Returns (undef, undef) if the domain name couldn't be expanded.

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