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package Discover; # $Id$
################################################################################
# Part of Mageia Online #
# Online service discovery library: #
# - autodetects nameservers and domains, #
# - and checks for DNS-declared Online service, #
# #
# Check http://www.dns-sd.org/ #
# #
# Copyright (C) 2005-2010 Mandriva #
# Copyright (C) 2010-2017 Mageia #
# #
# 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, see <http://www.gnu.org/licenses/>. #
################################################################################
use strict;
use Net::DNS;
use Data::Dumper;
use MDK::Common;
use Config::Auto; # CPAN Module. Seems not to be part of Mageia 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 commify_series {
(@_ == 0) ? '' :
(@_ == 1) ? $_[0] :
(@_ == 2) ? join(" and ", @_) :
join(", ", @_[0 .. ($#_-1)], "and $_[-1]");
}
#
sub search {
my $this = shift;
logsay "searching for a locally declared Mageia Online service";
my $resolv = Config::Auto::parse('/etc/resolv.conf');
my $servicetype = '_mdvonline._http._tcp.bonjour.';
my (@domains, @services);
! defined $resolv and logerr "No config found from /etc/resolv.conf.", return 0;
defined $resolv->{domain} and @domains = $resolv->{domain};
defined $resolv->{search} and push @domains, @{$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
foreach my $ns ( @{$resolv->{nameserver}} ) {
# for each possible service/domain
foreach my $serv ( @services ) {
logsay "trying ns $ns, service $serv";
my $ret = $this->find_service( $ns, $serv );
$ret and logsay "service found", return $ret;
}
}
logwarn "no dns-declared service found";
return 0;
};
# NOTE. here it is suppposed that for a given Service instance (PTR),
# there is only _one_ SRV record and _one_ TXT record matches.
# If there are more, no particular behaviour is expected as for now.
# NOTE. replace this code with a wrapper around dig?
sub find_service {
my ($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];
! defined $rr and 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() );
! defined $return->{config} and logwarn "But no config found.", return 0;
}
else {
logwarn "No matching TXT record found.";
logwarn $res->errorstring;
return 0;
}
return $return;
};
# translate the txt record* into a properly formatted hash.
#
# * consists of a list of 'key=value' strings; handled strings are:
# txtvers=n (integer)
# conf=a,b (string: name of the config,integer: set time)
# update=p (string: path to update server)
# service=s (string: path to service resource)
# user=s (string: default user name to use)
# pass=s (string: default password to use)
# auto=b (TRUE|FALSE: whether to act automatically or not)
# mobile=b (TRUE|FALSE: whether to act as a mobile agent or not)
#
sub parse_txt_config {
my ($this, @config) = @_;
my $retconfig;
foreach my $line (@config) {
# TODO match these with a regexp
my @line = split('=', $line);
my $key = shift(@line);
my $value = join('=', @line);
switch ($key) {
case 'txtvers' { $retconfig->{txtvers} = $value; }
case 'conf' {
my @co = split(',', $value);
$retconfig->{conf} = { 'name' => $co[0], 'time' => $co[1] };
}
case 'update' { $retconfig->{update} = $value; }
case 'service' { $retconfig->{service} = $value; }
case 'user' { $retconfig->{user} = $value; }
case 'pass' { $retconfig->{pass} = $value; }
case 'auto' { $retconfig->{auto} = 1; }
case 'mobile' { $retconfig->{mobile} = 1; }
else {}
}
}
$this->{config} = $retconfig;
return $retconfig;
};
1;
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