Net::DNS::Header

Section: User Contributed Perl Documentation (3)
Updated: 2006-09-18
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NAME

Net::DNS::Header - DNS packet header class  

SYNOPSIS

"use Net::DNS::Header;"  

DESCRIPTION

A "Net::DNS::Header" object represents the header portion of a DNS packet.  

METHODS

 

new

    $header = Net::DNS::Header->new;
    $header = Net::DNS::Header->new(\$data);

Without an argument, "new" creates a header object appropriate for making a DNS query.

If "new" is passed a reference to a scalar containing DNS packet data, it creates a header object from that data.

Returns undef if unable to create a header object (e.g., if the data is incomplete).  

print

    $header->print;

Dumps the header data to the standard output.  

string

    print $header->string;

Returns a string representation of the header object.  

id

    print "query id = ", $header->id, "\n";
    $header->id(1234);

Gets or sets the query identification number.  

qr

    print "query response flag = ", $header->qr, "\n";
    $header->qr(0);

Gets or sets the query response flag.  

opcode

    print "query opcode = ", $header->opcode, "\n";
    $header->opcode("UPDATE");

Gets or sets the query opcode (the purpose of the query).  

aa

    print "answer is ", $header->aa ? "" : "non-", "authoritative\n";
    $header->aa(0);

Gets or sets the authoritative answer flag.  

tc

    print "packet is ", $header->tc ? "" : "not ", "truncated\n";
    $header->tc(0);

Gets or sets the truncated packet flag.  

rd

    print "recursion was ", $header->rd ? "" : "not ", "desired\n";
    $header->rd(0);

Gets or sets the recursion desired flag.  

cd

    print "checking was ", $header->cd ? "not" : "", "desired\n";
    $header->cd(0);

Gets or sets the checking disabled flag.  

ra

    print "recursion is ", $header->ra ? "" : "not ", "available\n";
    $header->ra(0);

Gets or sets the recursion available flag.  

ad

    print "The result has ", $header->ad ? "" : "not", "been verified\n"

Relevant in DNSSEC context.

(The AD bit is only set on answers where signatures have been cryptographically verified or the server is authoritative for the data and is allowed to set the bit by policy.)  

rcode

    print "query response code = ", $header->rcode, "\n";
    $header->rcode("SERVFAIL");

Gets or sets the query response code (the status of the query).  

qdcount, zocount

    print "# of question records: ", $header->qdcount, "\n";
    $header->qdcount(2);

Gets or sets the number of records in the question section of the packet. In dynamic update packets, this field is known as "zocount" and refers to the number of RRs in the zone section.  

ancount, prcount

    print "# of answer records: ", $header->ancount, "\n";
    $header->ancount(5);

Gets or sets the number of records in the answer section of the packet. In dynamic update packets, this field is known as "prcount" and refers to the number of RRs in the prerequisite section.  

nscount, upcount

    print "# of authority records: ", $header->nscount, "\n";
    $header->nscount(2);

Gets or sets the number of records in the authority section of the packet. In dynamic update packets, this field is known as "upcount" and refers to the number of RRs in the update section.  

arcount, adcount

    print "# of additional records: ", $header->arcount, "\n";
    $header->arcount(3);

Gets or sets the number of records in the additional section of the packet. In dynamic update packets, this field is known as "adcount".  

data

    $hdata = $header->data;

Returns the header data in binary format, appropriate for use in a DNS query packet.  

COPYRIGHT

Copyright (c) 1997-2002 Michael Fuhr.

Portions Copyright (c) 2002-2004 Chris Reinhardt.

All rights reserved. This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.  

SEE ALSO

perl(1), Net::DNS, Net::DNS::Resolver, Net::DNS::Packet, Net::DNS::Update, Net::DNS::Question, Net::DNS::RR, RFC 1035 Section 4.1.1


 

Index

NAME
SYNOPSIS
DESCRIPTION
METHODS
new
print
string
id
qr
opcode
aa
tc
rd
cd
ra
ad
rcode
qdcount, zocount
ancount, prcount
nscount, upcount
arcount, adcount
data
COPYRIGHT
SEE ALSO

linux.jgfs.net manual pages