Frederik Lindenaar
de0f57806c
Changed the behaviour of the update command so that it would not just pick the remote address if no ip parameter was provided. To autodetect the IP address it is now mandatory to pass value auto (so ip=auto) for the ipv4addr or ipv6addr. This also allows to specify which address should be autodetected and have a static address passed for ipv4 and have the ipv6 address autodetected for multi-network systems (also closes #6)
381 lines
13 KiB
Perl
Executable File
381 lines
13 KiB
Perl
Executable File
#!/usr/bin/perl
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#
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# dyndns.pl - CGI-BIN script to handle Dynamic DNS updates through http
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#
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# Version 1.1, latest version, documentation and bugtracker available at:
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# https://gitlab.lindenaar.net/scripts/dyndns
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#
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# Copyright (c) 2013 - 2019 Frederik Lindenaar
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#
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# This script is free software: you can redistribute and/or modify it under the
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# terms of version 3 of the GNU General Public License as published by the Free
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# Software Foundation, or (at your option) any later version of the license.
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#
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# This script is distributed in the hope that it will be useful but WITHOUT ANY
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# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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# A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License along with
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# this program. If not, visit <http://www.gnu.org/licenses/> to download it.
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#
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use strict;
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use CGI;
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use POSIX;
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use Net::DNS;
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use feature 'state';
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##############################
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# Configuration section
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my $DNSServer = '192.168.1.1'; # DNS Server to communicate with (use IP!)
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my $ExpandCNAMEs = 1; # CNAME levels to expand (0 to disable)
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my $AllowDebugKey = 'on'; # Debuging, 'off' to disable, '' for always on
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# and other values to enable with debug= param.
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my $AuthMode = 'remote'; # either 'static', 'remote' or 'both'
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my $StaticSigner = ''; # required for AuthMode 'static' or 'both'
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my $StaticKey = ''; # required for AuthMode 'static' or 'both'
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my $RequireRR = ''; # Require existing record of this type for upd.
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my $ExpireAfter = '1w'; # Expire time for registrations in minutes,
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# hours, weeks or seconds. format: [0-9]+[mhws]?
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my @ReplaceRR = ('A', 'AAAA', 'TXT'); # Records types to replace in update
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my $UpdateTXT = 'Last DynDNS update on ';
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my $DeleteTXT = 'DynDNS cleared on ';
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##############################
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# Support functions
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my %months = (Jan=> 0, Feb=> 1, Mar=> 2, Apr=> 3, May=>4, Jun=> 5, Jul=> 6,
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Aug=> 7, Sep=> 8, Sep=> 8, Oct=> 9, Nov=> 10, Dec=> 11);
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# Parse the date and return time for: Sun May 26 21:22:15 2013
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sub parse_localtime($) {
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my ($day, $month, $mday, $time, $year)=split(' ', $_[0]);
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return mktime(reverse(split(':',$time)),$mday,$months{$month},$year-1900);
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}
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sub is_ipv4 { return $_[0]=~/^((25[0-5]|(2[0-4]|[01]?[0-9]?)[0-9])(\.|$)){4}/; }
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sub is_ipv6 { return $_[0]=~/^([0-9a-fA-F]{0,4}(:|$)){3,8}/i; }
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sub periodSeconds($) {
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my ($number, $units) = ($_[0]=~/^(\d+)([smhdw])?$/);
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if($number && $units && $units cmp 's') {
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$number *= 60; # Convert to minutes
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if($units cmp 'm') {
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$number *= 60; # Convert to hours
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if($units cmp 'h') {
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$number *= 24; # Convert to days
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if($units cmp 'd') {
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$number *= 7; # Convert to weeks
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}
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}
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}
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}
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return $number;
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}
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# Provide a resolver object for further use, re-using the initially created one
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sub getResolver() {
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state $resolver;
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unless($resolver) {
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$resolver = Net::DNS::Resolver->new(
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nameservers => [ $DNSServer ],
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recurse => 0,
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);
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}
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return $resolver;
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}
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my %DNS_label = (
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A => 'IPv4 Address',
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AAAA => 'IPv6 Address',
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CNAME => 'Alias',
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TXT => 'Additional Information',
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MX => 'Mail Server',
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NS => 'Name Server',
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HINFO => 'Host Information',
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);
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sub DNS_decode_rr($) {
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my ($rr) = @_;
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return $rr->address if($rr->type eq 'A');
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return $rr->address if($rr->type eq 'AAAA');
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return lc($rr->cname) if($rr->type eq 'CNAME');
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return $rr->txtdata if($rr->type eq 'TXT');
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return $rr->nsdname if($rr->type eq 'NS');
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return $rr->exchange.' (priority '.$rr->preference.')' if($rr->type eq 'MX');
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return $rr->cpu.', '.$rr->os if($rr->type eq 'HINFO');
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die "No support for $rr " . $rr->type . " in DNS_decode_rr()!, aborted!";
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}
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# Retrieve a single value from the DNS server of a given type or everything
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sub DNS_get($;$) {
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my ($host, $type) = @_;
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if (my $response = getResolver()->send($host, $type || 'ANY')) {
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return $response unless($type);
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foreach my $rr ($response->answer) {
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next unless $rr->type eq $type;
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return DNS_decode_rr($rr);
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}
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} else {
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die 'DNS query failed: ', getResolver()->errorstring, "\n";
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}
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}
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# Check whether the hostname provided is actually a CNAME, returns the host
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# it points to in case of a CNAME or the original hostname if it is not.
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sub expand_CNAME($;$) {
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my ($host, @found) = @_;
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if(my $cname=DNS_get($host, 'CNAME')) {
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push(@found, $host);
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die $found[0]."has > $ExpandCNAMEs level deep CNAME chain, aborting!\n"
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unless($#found < $ExpandCNAMEs);
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foreach my $r (@found) {
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die "found CNAME loop for $host, aborting!\n" if($cname eq $r);
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}
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return &expand_CNAME($cname, @found);
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}
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return $host;
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}
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# Get signer and key CGI paramseters, abort with HTTP 400 error if not present
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sub get_authinfo($$) {
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my ($cgi, $host) = @_;
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# Get signer and key parameters
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my $signer = ($AuthMode eq 'static') ? $StaticSigner : ($cgi->param('user')
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|| (($AuthMode eq 'both') ? $StaticSigner : $host));
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my $key = ($AuthMode eq 'static') ? $StaticKey : ($cgi->param('secret')
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|| (($AuthMode eq 'both') ? $StaticSigner : undef));
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# Ensure we have a value for signer and key, otherwise abort the processing
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if($signer eq '' or $key eq '') {
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print $cgi->header(-status=>400, -type=>'text/plain'),
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"ERROR - No/incomplete authentication information provided\n";
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exit
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}
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# and return the values
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return($signer, $key);
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}
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# Perform an DNS Update for a single host
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sub DNS_Update($$$$$$$) {
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my ($dnsdomain, $dnshost, $ipv4, $ipv6, $signer, $key, $debug) = @_;
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my $dnsupdate = Net::DNS::Update->new($dnsdomain);
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# If $RequireRR is set, ensure an records of specified type exist for the name
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$dnsupdate->push(pre => yxrrset("$dnshost. $RequireRR")) if($RequireRR);
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# Replace any existing A, AAAA and TXT entries (update was requested)
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foreach my $rrtype (@ReplaceRR) {
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$dnsupdate->push(update=>rr_del("$dnshost. $rrtype"));
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}
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# Add new A and AAAA record based on whether ipv4 and ipv6 address provided
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$dnsupdate->push(update=>rr_add("$dnshost. 3600 A $ipv4")) if($ipv4);
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$dnsupdate->push(update=>rr_add("$dnshost. 3600 AAAA $ipv6")) if($ipv6);
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# Always add a new TXT record with the timestamp of the last update
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my $txt = ($ipv4 or $ipv6) ? $UpdateTXT : $DeleteTXT;
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$dnsupdate->push(update=>rr_add($dnshost. '. 3600 TXT "' . $txt . localtime()
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. '"')) if($txt);
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# Sign the request with the signer and key
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$dnsupdate->sign_tsig($signer, $key);
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my $debugmessage = ($debug)
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? "\n\n\n========================================================\n" .
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$dnsupdate->string . "\n"
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: "\n";
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if(my $response = getResolver()->send($dnsupdate)) {
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$debugmessage .= $response->string . "\n" if($debug);
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if ($response->header->rcode eq 'NOERROR') {
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return (200, "OK - DNS update for $dnshost succeeded: " .
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$response->header->rcode . $debugmessage);
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} else {
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# REFUSED, FORMERR
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return (400, "ERROR - DNS update for $dnshost failed: " .
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$response->header->rcode . $debugmessage);
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}
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} else {
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return (503, 'ERROR - DNS update for $dnshost failed: '.
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getResolver()->errorstring. $debugmessage);
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}
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}
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##############################
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# Handlers for the different requests
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sub handle_update($$$$$$) {
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my ($cgi, $mode, $host, $dnshost, $dnsdomain, $debug) = @_;
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my ($signer, $key) = get_authinfo($cgi, $host);
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# perform the action
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my ($statuscode, $statusmessage);
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if($mode eq 'delete') {
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($statuscode, $statusmessage) =
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DNS_Update($dnsdomain, $dnshost, undef, undef, $signer, $key, $debug)
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} else {
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# Get ipv4, and ipv6 parameters
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my $remote_addr = $cgi->remote_addr;
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my $ipv4addr = $cgi->param('ipv4addr') || $cgi->param('ip');
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if ($ipv4addr == 'auto') {
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$ipv4addr = is_ipv4($remote_addr) ? $remote_addr : undef;
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}
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my $ipv6addr = $cgi->param('ipv6addr') || $cgi->param('ipv6');
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if ($ipv6addr == 'auto') {
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$ipv6addr = is_ipv6($remote_addr) ? $remote_addr : undef;
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}
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($statuscode, $statusmessage) =
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DNS_Update($dnsdomain, $dnshost, $ipv4addr, $ipv6addr, $signer, $key, $debug);
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}
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# And report back the status
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print $cgi->header(-status=>$statuscode, -type=>'text/plain'), $statusmessage;
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}
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sub handle_expire($$$$$$) {
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my ($cgi, $mode, $host, $dnshost, $dnsdomain, $debug) = @_;
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my ($signer, $key) = get_authinfo($cgi, $host);
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my $debugmsg = ($debug) ? "\n" : '';
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# perform the action
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if(my $period = periodSeconds($ExpireAfter)) {
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my $validafter = time - $period;
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if($debug) {
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$debugmsg .= "ExpireAfter $ExpireAfter, expiring all entries older than ";
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$debugmsg .= localtime($validafter) . "\n";
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}
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foreach my $rr (getResolver->axfr($dnsdomain)) {
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next if($rr->name eq $dnsdomain);
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if($rr->type eq 'TXT' &&
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$rr->txtdata=~/$UpdateTXT(.*\d\d:\d\d:\d\d \d{4})$/){
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if(my $lastupdate = parse_localtime($1)) {
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DNS_Update($dnsdomain, $dnshost, undef, undef, $signer, $key, $debug)
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unless($lastupdate > $validafter);
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if($debug) {
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$debugmsg .= ($lastupdate > $validafter) ? 'Keeping ' : 'Expiring ';
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$debugmsg .= $rr->name . " last update ($1)\n";
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}
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} elsif($debug) {
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$debugmsg .= 'Skipping '. $rr->name ." TXT: '". $rr->txtdata ."'\n";
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}
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}
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}
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# And report back the status
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print $cgi->header(-status=>200, -type=>'text/plain'),
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"OK - DNS expiry for $dnsdomain succeeded\n" . $debugmsg;
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}
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}
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sub handle_view($$$$$$) {
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my ($cgi, $mode, $host, $dnshost, $dnsdomain, $debug) = @_;
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my $title = "DynDNS Updater - $host";
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print $cgi->header(-status=>200),
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$cgi->start_html(-title => $title),
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$cgi->h1($title);
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print $cgi->p("$host resolves to $dnshost") if($host cmp $dnshost);
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print $cgi->p("Current DNS information for $dnshost:"),
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$cgi->start_table,
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$cgi->Tr({-align=>'LEFT',-valign=>'TOP'}, [
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$cgi->th(['Field', 'Value'])
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]);
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foreach my $rr (DNS_get($dnshost)->answer) {
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if(my $label = $DNS_label{$rr->type}) {
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print $cgi->Tr([ $cgi->td([$label, DNS_decode_rr($rr)]) ]);
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}
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}
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print $cgi->end_table();
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print $cgi->end_html();
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}
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sub handle_list($$$$$$) {
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my ($cgi, $mode, $host, $dnshost, $dnsdomain, $debug) = @_;
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my $title = "DynDNS Updater - $dnsdomain";
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print $cgi->header(-status=>200),
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$cgi->start_html(-title => $title),
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$cgi->h1($title);
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print $cgi->p("Current DNS information for $dnsdomain:"),
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$cgi->start_table,
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$cgi->Tr({-align=>'LEFT',-valign=>'TOP'}, [
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$cgi->th(['Name', 'Field', 'Value'])
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]);
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my $lastname = '';
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foreach my $rr (getResolver->axfr($dnsdomain)) {
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next if($rr->name eq $dnsdomain);
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if(my $label = $DNS_label{$rr->type}) {
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print $cgi->Tr([ $cgi->td([ ($lastname cmp $rr->name) ? $rr->name : '',
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$label, DNS_decode_rr($rr)]) ]);
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$lastname = $rr->name;
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}
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}
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print $cgi->end_table();
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print $cgi->end_html();
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}
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my $cgi = CGI->new;
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##############################
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# Validate Configuration
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my $CE = 'Configuration Error:';
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die "$CE \$AuthMode '$AuthMode' is unsupported must be remote, static or both\n"
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unless $AuthMode=~/remote|static|both/;
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die "$CE \$StaticSigner must be set for \$AuthMode '$AuthMode'\n"
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unless ($StaticSigner or $AuthMode eq 'remote');
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die "$CE \$StaticKey must be set for \$AuthMode '$AuthMode'\n"
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unless ($StaticKey or $AuthMode eq 'remote');
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die "$CE \$RequireRR is set to unsupported type '$RequireRR'\n"
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if ($RequireRR and not $DNS_label{$RequireRR});
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die "$CE \$ExpireAfter '$ExpireAfter' is not supported\n"
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unless ($ExpireAfter=~/^\d+[smhw]$/);
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die "$CE \$UpdateTXT must be set when \$ExpireAfter is set\n"
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if($ExpireAfter and not $UpdateTXT);
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foreach my $rrtype (@ReplaceRR) {
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die "$CE \$ReplaceRR contains unsupported type '$rrtype'\n"
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unless ($DNS_label{$rrtype});
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}
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##############################
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# Determine what to do and fetch the input parameters
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my $mode = $cgi->path_info || $cgi->param('mode') || 'view';
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$mode=~s/^\/([^\/]+)(\/(.*))?/$1/;
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my $host = $cgi->param('host') || $3;
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my $debug = ($AllowDebugKey eq 'off') ? 0 : ($AllowDebugKey eq ($cgi->param('debug') || ''));
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##############################
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# Dispatch the request to the correct handler
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my %handlers = (
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view => \&handle_view,
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update => \&handle_update,
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delete => \&handle_update,
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list => \&handle_list,
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expire => \&handle_expire,
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);
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if($host eq '' and $mode cmp 'list' and $mode cmp 'expire') {
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print $cgi->header(-status=>400, -type=>'text/plain'),
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"ERROR - No host name to act on specified\n";
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} elsif(my $handler = $handlers{$mode}) {
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# Replace provided host with that of a CNAME it points to and determine domain
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my $dnshost = ($host) ? expand_CNAME($host) : undef;
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my $dnsdomain = $cgi->param('domain') || ($dnshost=~/\.(.*)$/)[0];
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$handler->($cgi, $mode, $host, $dnshost, $dnsdomain, $debug);
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} else {
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print $cgi->header(-status=>($cgi->path_info) ? 404 : 400,
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-type=>'text/plain'),
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"ERROR - File Not Found / Invalid Mode '$mode' specified\n";
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}
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