summaryrefslogtreecommitdiffstats
path: root/Discover.pm
blob: 7fc3f110a95f04c5a68b62d1b1688507d462e5d1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
package Discover; # $Id$

################################################################################
# Part of Mandriva Online                                                      #
# Online service discovery library:                                            #
# - autodetects nameservers and domains,                                       #
# - and checks for DNS-declared Online service,                                #
#                                                                              #
# Check http://www.dns-sd.org/                                                 #
#                                                                              #
# Copyright (C) 2005 Mandriva                                                  #
#                                                                              #
# Romain d'Alverny <rdalverny at mandriva dot com>                             #
#                                                                              #
# This program is free software; you can redistribute it and/or modify         #
# it under the terms of the GNU General Public License Version 2 as            #
# published by the Free Software Foundation.                                   #
#                                                                              #
# This program 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 General Public License for more details.                                 #
#                                                                              #
# You should have received a copy of the GNU General Public License            #
# along with this program; if not, write to the Free Software                  #
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.   #
################################################################################

use strict;
use Net::DNS;
use Data::Dumper;
use MDK::Common;
use Config::Auto; # CPAN Module. Seems not to be part of Mandriva packages yet.
use Switch;

use Log::Agent; # use settings from main file

my $VERSION = '0.01';

#
sub new
{
	my $self = {};
	bless $self, "Discover";
	logsay "DNS Service Discovery module $VERSION";
	return $self;
}

#
sub init
{
	my $this = shift;
	$this->{domainname} = '';
	$this->{zone}       = '';
	$this->{service}    = '';
	$this->{nameserver} = '';
	$this->{instance}   = '';
};

#
sub trim {
	my $s = shift;
	$s =~ s/^\s+//;
	$s =~ s/\s+$//;
	return $s;
};

#
sub commify_series {
    (@_ == 0) ? '' :
    (@_ == 1) ? $_[0] :
    (@_ == 2) ? join(" and ", @_) :
                join(", ", @_[0 .. ($#_-1)], "and $_[-1]");
};

#
sub search {
	my $this = shift;
	
	logsay "searching for a locally declared Mandriva Online service";

	my $resolv      = Config::Auto::parse('/etc/resolv.conf');
	my $servicetype = '_mdvonline._http._tcp.bonjour.';
	my @domains     = ();
	my @services    = ();
	
	if( ! defined $resolv ) {
		logerr "No config found from /etc/resolv.conf .";
		return 0;	
	}
	
	if( defined $resolv->{domain} ) {
		@domains = $resolv->{domain};
	}
	if( defined $resolv->{search} ) {
		push( @domains, @{$resolv->{search}} );
	}
	
	@domains = uniq(@domains);
	for my $domain ( @domains ) {
		push( @services, $servicetype . $domain );
	}
	logsay "found domains: " . commify_series(@domains);
	logsay "found nameservers: " . commify_series(@{$resolv->{nameserver}});

	# for dev.
	@{$resolv->{nameserver}} = qw(localhost);
	
	# will try each nameserver listed
	for my $ns ( @{$resolv->{nameserver}} ) {
		# for each possible service/domain
		for my $serv ( @services ) {
			logsay "trying ns $ns, service $serv";
			my $ret = $this->find_service( $ns, $serv );
			if( $ret ) {
				logsay "search is over: a service has been found.";
				return $ret;
			}
		}
	}
	logwarn "no dns-declared service found";
	return 0;
};
 
# NOTE. here it is suppposed that for a given Service instance (PTR),
# there is only _one_ SRV record and _one_ TXT record matches.
# If there are more, no particular behaviour is expected as for now.
sub find_service {
	my ($this, $nameserver, $service) = @_;
	my $return;

	# lower the values to make it faster to give up
	my $retry = 2;   # default is 120
	my $retrans = 2; # default is 5
	logsay "retry rate is set to $retry; retrans rate is set to $retrans";
	my $res = Net::DNS::Resolver->new(
					retry => $retry,
					retrans => $retrans,
					#debug => 1
	);
	
	# TODO make sure the nameserver answers, or set a timeout.
	$res->nameservers( $nameserver );

	# 1. search for any PTR record matching the service name	
	logsay "ns $nameserver: PTR $service ?";
	my $query = $res->query( $service, 'PTR' );
	my $instanceName;
	if( $query ) {
		# TODO better parsing of the struct
		my $rr = $query->{answer}[0];
		if( ! defined $rr ) {
			logerr "not expected format found in PTR record.";
			return 0;	
		}
		$instanceName = $rr->ptrdname;
		$instanceName =~ s/\\032/ /g;
		logsay "found '$instanceName'";
		$this->{serviceInstanceName} = $instanceName;
	}
	else {
		logwarn "no PTR record found.";
		logwarn $res->errorstring;
		return 0;	
	}
	
	# 2. for each service instance found, look up for SRV/TXT records.
	logsay "ns $nameserver: SRV '$instanceName' ?";
	$query = $res->query( $instanceName, 'SRV' );
	if( $query ) {
		my $rr = $query->{answer}[0];
		logsay "yes: " . $rr->target . ":" . $rr->port;
		$this->{server} = { priority => $rr->priority, weight => $rr->weight,
							port => $rr->port, host => $rr->target };
		$return->{server} = $this->{server};
	}
	else {
		logwarn "no matching SRV record found.";
		logwarn $res->errorstring;
		return 0;
	}
	
	logsay "ns $nameserver: TXT '$instanceName' ?";
	$query = $res->query( $instanceName, 'TXT' );
	if( $query ) {
		my $rr = $query->{answer}[0];
		logsay "yes: " . join(', ', $rr->char_str_list() );
		$return->{config} = $this->parse_txt_config( $rr->char_str_list() );
		if( ! defined $return->{config} ) {
			logwarn "But no config found.";
			return 0;	
		}
	}
	else {
		logwarn "No matching TXT record found.";
		logwarn $res->errorstring;
		return 0;
	}
	return $return;
};

# translate the txt records into a properly formatted hash.
sub parse_txt_config {
	my ($this, @config) = @_;
	my $retconfig;
	
	for my $line ( @config ) {
		my @line = split('=', $line);
		my $key = $line[0];
		shift(@line);
		my $value = join('=', @line);
		#print "key: $key\tvalue: $value\n";	
		switch( $key ) {
			case 'txtvers' { $retconfig->{txtvers} = $value; }
			case 'conf' {
				my @co = split(',', $value);
				$retconfig->{conf} = { 'name' => $co[0], 'time' => $co[1]	};
			}
			case 'update' {
				my @up = split(',', $value);
				$retconfig->{update} = { 'type' => $up[0], 'path' => $up[1] };
			}
			case 'service' { $retconfig->{service} = $value; }
			case 'user' { $retconfig->{user} = $value; }
			case 'pass' { $retconfig->{pass} = $value; }
			case 'auto' { $retconfig->{auto} = 1; }
			else {}
		}
	}
	$this->{config} = $retconfig;
	return $retconfig;
};

1;