1Net::DNS::Nameserver(3)User Contributed Perl DocumentatioNnet::DNS::Nameserver(3)
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6 Net::DNS::Nameserver - DNS server class
7
9 "use Net::DNS::Nameserver;"
10
12 Instances of the "Net::DNS::Nameserver" class represent DNS server
13 objects. See "EXAMPLE" for an example.
14
16 new
17 my $ns = Net::DNS::Nameserver->new(
19 LocalAddr => "10.1.2.3",
20 LocalPort => "5353",
21 ReplyHandler => \&reply_handler,
22 Verbose => 1
23 );
24 my $ns = Net::DNS::Nameserver->new(
26 LocalAddr => ['::1' , '127.0.0.1' ],
27 LocalPort => "5353",
28 ReplyHandler => \&reply_handler,
29 Verbose => 1
30 );
31 Creates a nameserver object. Attributes are:
33 LocalAddr IP address on which to listen. Defaults to INADDR_ANY.
35 LocalPort Port on which to listen. Defaults to 53.
36 ReplyHandler Reference to reply-handling
37 subroutine Required.
38 Verbose Print info about received
39 queries. Defaults to 0 (off).
40 The LocalAddr attribute may alternatively be specified as a list of IP
42 addresses to listen to.
43 If IO::Socket::INET6 and Socket6 are available on the system you can
45 also list IPv6 addresses and the default is '0' (listen on all inter‐
46 faces on IPv6 and IPv4);
47 The ReplyHandler subroutine is passed the query name, query class,
49 query type and optionally an argument containing header bit settings
50 (see below). It must return the response code and references to the
51 answer, authority, and additional sections of the response. Common
52 response codes are:
53 NOERROR No error
55 FORMERR Format error
56 SERVFAIL Server failure
57 NXDOMAIN Non-existent domain (name doesn't exist)
58 NOTIMP Not implemented
59 REFUSED Query refused
60 For advanced usage there is an optional argument containing an hashref
62 with the settings for the "aa", "ra", and "ad" header bits. The argu‐
63 ment is of the form "{ ad => 1, aa => 0, ra => 1 }".
64 See RFC 1035 and the IANA dns-parameters file for more information:
66 ftp://ftp.rfc-editor.org/in-notes/rfc1035.txt
68 http://www.isi.edu/in-notes/iana/assignments/dns-parameters
69 The nameserver will listen for both UDP and TCP connections. On Unix-
71 like systems, the program will probably have to run as root to listen
72 on the default port, 53. A non-privileged user should be able to lis‐
73 ten on ports 1024 and higher.
74 Returns a Net::DNS::Nameserver object, or undef if the object couldn't
76 be created.
77 See "EXAMPLE" for an example.
79 main_loop
81 $ns->main_loop;
83 Start accepting queries. Calling main_loop never returns.
85 get_open_tcp
87 In scalar context returns the number of TCP connections for which state
89 is maintained. In array context it returns IO::Socket objects, these
90 could be useful for troubleshooting but be careful using them.
91
93 The following example will listen on port 5353 and respond to all
94 queries for A records with the IP address 10.1.2.3. All other queries
95 will be answered with NXDOMAIN. Authority and additional sections are
96 left empty. The $peerhost variable catches the IP address of the peer
97 host, so that additional filtering on its basis may be applied.
98 #!/usr/bin/perl
100 use Net::DNS::Nameserver;
102 use strict;
103 use warnings;
104 sub reply_handler {
106 my ($qname, $qclass, $qtype, $peerhost) = @_;
107 my ($rcode, @ans, @auth, @add);
108 if ($qtype eq "A" && qname eq "foo.example.com" ) {
110 my ($ttl, $rdata) = (3600, "10.1.2.3");
111 push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype $rdata");
112 $rcode = "NOERROR";
113 }elsif( qname eq "foo.example.com" ) {
114 $rcode = "NOERROR";
115 }else{
117 $rcode = "NXDOMAIN";
118 }
119 # mark the answer as authoritive (by setting the 'aa' flag
121 return ($rcode, \@ans, \@auth, \@add, { aa => 1 });
122 }
123 my $ns = Net::DNS::Nameserver->new(
125 LocalPort => 5353,
126 ReplyHandler => \&reply_handler,
127 Verbose => 1,
128 ) ⎪⎪ die "couldn't create nameserver object\n";
129 $ns->main_loop;
131
133 Limitations in perl 5.8.6 makes it impossible to guarantee that replies
134 to UDP queries from Net::DNS::Nameserver are sent from the IP-address
135 they were received on. This is a problem for machines with multiple IP-
136 addresses and causes violation of RFC2181 section 4. Thus a UDP socket
137 created listening to INADDR_ANY (all available IP-addresses) will reply
138 not necessarily with the source address being the one to which the
139 request was sent, but rather with the address that the operating system
140 choses. This is also often called "the closest address". This should
141 really only be a problem on a server which has more than one IP-address
142 (besides localhost - any experience with IPv6 complications here, would
143 be nice). If this is a problem for you, a work-around would be to not
144 listen to INADDR_ANY but to specify each address that you want this
145 module to listen on. A seperate set of sockets will then be created for
146 each IP-address.
147
149 Copyright (c) 1997-2002 Michael Fuhr.
150 Portions Copyright (c) 2002-2004 Chris Reinhardt.
152 Portions Copyright (c) 2005 O.M, Kolkman, RIPE NCC.
154 Portions Copyright (c) 2005 Robert Martin-Legene.
156 All rights reserved. This program is free software; you may redis‐
158 tribute it and/or modify it under the same terms as Perl itself.
159
161 perl(1), Net::DNS, Net::DNS::Resolver, Net::DNS::Packet,
162 Net::DNS::Update, Net::DNS::Header, Net::DNS::Question, Net::DNS::RR,
163 RFC 1035
164perl v5.8.8 2007-08-01 Net::DNS::Nameserver(3)