Net::DNS::Header(3pm)

1Net::DNS::Header(3)   User Contributed Perl Documentation  Net::DNS::Header(3)
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NAME

6       Net::DNS::Header - DNS packet header
7

SYNOPSIS

9           use Net::DNS;
10
11           $packet = new Net::DNS::Packet;
12           $header = $packet->header;
13

DESCRIPTION

15       "Net::DNS::Header" represents the header portion of a DNS packet.
16

METHODS

18   new
19           $header = new Net::DNS::Header($packet);
20
21       Constructor method which returns a "Net::DNS::Header" object
22       representing the header section of the specified packet.
23
24   string
25           print $packet->header->string;
26
27       Returns a string representation of the packet header.
28
29   id
30           print "query id = ", $packet->header->id, "\n";
31           $packet->header->id(1234);
32
33       Gets or sets the query identification number.
34
35       A random value is assigned if the argument value is undefined.
36
37   opcode
38           print "query opcode = ", $packet->header->opcode, "\n";
39           $packet->header->opcode("UPDATE");
40
41       Gets or sets the query opcode (the purpose of the query).
42
43   rcode
44           print "query response code = ", $packet->header->rcode, "\n";
45           $packet->header->rcode("SERVFAIL");
46
47       Gets or sets the query response code (the status of the query).
48
49   qr
50           print "query response flag = ", $packet->header->qr, "\n";
51           $packet->header->qr(0);
52
53       Gets or sets the query response flag.
54
55   aa
56           print "answer is ", $packet->header->aa ? "" : "non-", "authoritative\n";
57           $packet->header->aa(0);
58
59       Gets or sets the authoritative answer flag.
60
61   tc
62           print "packet is ", $packet->header->tc ? "" : "not ", "truncated\n";
63           $packet->header->tc(0);
64
65       Gets or sets the truncated packet flag.
66
67   rd
68           print "recursion was ", $packet->header->rd ? "" : "not ", "desired\n";
69           $packet->header->rd(0);
70
71       Gets or sets the recursion desired flag.
72
73   ra
74           print "recursion is ", $packet->header->ra ? "" : "not ", "available\n";
75           $packet->header->ra(0);
76
77       Gets or sets the recursion available flag.
78
79   z
80       Unassigned bit, should always be zero.
81
82   ad
83           print "The result has ", $packet->header->ad ? "" : "not", "been verified\n";
84
85       Relevant in DNSSEC context.
86
87       (The AD bit is only set on answers where signatures have been
88       cryptographically verified or the server is authoritative for the data
89       and is allowed to set the bit by policy.)
90
91   cd
92           print "checking was ", $packet->header->cd ? "not" : "", "desired\n";
93           $packet->header->cd(0);
94
95       Gets or sets the checking disabled flag.
96
97   qdcount, zocount
98           print "# of question records: ", $packet->header->qdcount, "\n";
99
100       Returns the number of records in the question section of the packet.
101       In dynamic update packets, this field is known as "zocount" and refers
102       to the number of RRs in the zone section.
103
104   ancount, prcount
105           print "# of answer records: ", $packet->header->ancount, "\n";
106
107       Returns the number of records in the answer section of the packet which
108       may, in the case of corrupt packets, differ from the actual number of
109       records.  In dynamic update packets, this field is known as "prcount"
110       and refers to the number of RRs in the prerequisite section.
111
112   nscount, upcount
113           print "# of authority records: ", $packet->header->nscount, "\n";
114
115       Returns the number of records in the authority section of the packet
116       which may, in the case of corrupt packets, differ from the actual
117       number of records.  In dynamic update packets, this field is known as
118       "upcount" and refers to the number of RRs in the update section.
119
120   arcount, adcount
121           print "# of additional records: ", $packet->header->arcount, "\n";
122
123       Returns the number of records in the additional section of the packet
124       which may, in the case of corrupt packets, differ from the actual
125       number of records.  In dynamic update packets, this field is known as
126       "adcount".
127

EDNS Protocol Extensions

129   do
130           print "DNSSEC_OK flag was ", $packet->header->do ? "not" : "", "set\n";
131           $packet->header->do(1);
132
133       Gets or sets the EDNS DNSSEC OK flag.
134
135   Extended rcode
136       EDNS extended rcodes are handled transparently by
137       $packet->header->rcode().
138
139   UDP packet size
140           $udp_max = $packet->edns->size;
141           $udp_max = $packet->header->size;
142
143       EDNS offers a mechanism to advertise the maximum UDP packet size which
144       can be assembled by the local network stack.
145
146       UDP size advertisement can be viewed as either a header extension or an
147       EDNS feature.  Endless debate is avoided by supporting both views.
148
149   edns
150           $header  = $packet->header;
151           $version = $header->edns->version;
152           @options = $header->edns->options;
153           $option  = $header->edns->option(n);
154           $udp_max = $packet->edns->size;
155
156       Auxiliary function which provides access to the EDNS protocol extension
157       OPT RR.
158

COPYRIGHT

160       Copyright (c)1997-2002 Michael Fuhr.
161
162       Portions Copyright (c)2002-2004 Chris Reinhardt.
163
164       Portions Copyright (c)2012 Dick Franks.
165
166       All rights reserved.
167
168       This program is free software; you may redistribute it and/or modify it
169       under the same terms as Perl itself.
170

NAME

SYNOPSIS

DESCRIPTION

METHODS

EDNS Protocol Extensions

COPYRIGHT

SEE ALSO