Frederik Lindenaar
1e04ec37c3
updated documentation to reflect the migration to Gitea correctly handle IPv4 or IPv6 addresses to be empty added Remote, IPv4 and IPv6 addresses to the debug output
451 lines
16 KiB
Perl
Executable File
451 lines
16 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 1.2, latest version, documentation and bugtracker available at:
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# https://gitea.lindenaar.net/scripts/dyndns
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#
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# Copyright (c) 2013 - 2025 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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my $ConfigFile = 'optional'; # hardcoded, either optional, required or ignore
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##############################
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# Configuration section (defaults, can be set in config file)
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my $DNSServer = '192.168.1.1'; # DNS Server to communicate with (use IP!)
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my @DNSDomain = ( '?', '!', 0 ); # DNS Domain to support, match hostname with:
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# '?': take domain name from parameter 'domain'
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# '!': take domain name from virtualhost name
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# 0: take domain from hostname
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# positive number: last # parts from hostname
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# negative number: last # parts from virtualhost
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# any other string: use if hostname ends on it
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my $ExpandCNAMEs = 1; # CNAME levels to expand (0 to disable)
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my $AllowDebugKey = 'off'; # Debuging, 'off' to disable, '' for always on
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# and other values to enable with debug= param.
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my $DomainListKey = 'off'; # List operation, 'off' to disable, '' to always
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# allow and other values to enable with secret
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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 $RecordTTL = '1h'; # TTL for created records, format: [0-9]+[mhws]?
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my $UpdateTXT = 'Last DynDNS update on'; # if set add TXT with this+date on update
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my $DeleteTXT = 'DynDNS cleared on'; # if set add TXT with this+date on delete
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##############################
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# Support functions
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my %months = (Jan=> 0, Feb=> 1, Mar=> 2, Apr=> 3, May=>4, Jun=> 5, Jul=> 6,
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Aug=> 7, Sep=> 8, Sep=> 8, Oct=> 9, Nov=> 10, Dec=> 11);
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# Parse the date and return time for: Sun May 26 21:22:15 2013
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sub parse_localtime($) {
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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 *= ($units eq 'm') ? 60 # Seconds per minute
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: ($units eq 'h') ? 3600 # Seconds per hour
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: ($units eq 'd') ? 86400 # Seconds per day
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: 604800; # Seconds per week
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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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##############################
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# Initialize CGI, determine whether debugging is on and declaire fail method
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my $cgi = CGI->new;
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my $debug = ($AllowDebugKey cmp 'off') && (($AllowDebugKey eq '') || ($AllowDebugKey eq $cgi->param('debug')) );
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my $SE = 'System Error';
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my $CE = 'Configuration Error';
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my $PE = 'Required parameter missing';
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sub fail($$;$) {
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my ($errormsg, $debugmsg, $exitcode) = @_;
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print $cgi->header(-status=>$exitcode || 503, -type=>'text/plain'),
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"ERROR - $errormsg" . ($debug ? ": $debugmsg\n" : "\n");
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exit 0;
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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) = @_;
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my @found;
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while(my $cname = DNS_get($host, 'CNAME')) {
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push(@found, $host);
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$host = $cname;
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fail("DNS CNAME Not supported", "$found[0] points to a CNAME but this is not supported", 400)
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unless($ExpandCNAMEs);
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fail("DNS CNAME Chain Error", "$found[0] has > $ExpandCNAMEs level deep CNAME chain", 400)
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unless($#found < $ExpandCNAMEs);
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foreach my $r (@found) {
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fail("DNS CNAME Loop", "found CNAME loop for $found[0]", 400) if($cname eq $r);
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}
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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') ? $StaticSigner : undef));
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# Ensure we have a value for signer and key, otherwise abort the processing
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fail($PE, "No/incomplete authentication information provided", 400)
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if($signer eq '' or $key eq '');
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# and return the values
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return($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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my $ttl = periodSeconds($RecordTTL);
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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. $ttl A $ipv4")) if($ipv4);
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$dnsupdate->push(update=>rr_add("$dnshost. $ttl AAAA $ipv6")) if($ipv6);
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# Add a TXT record with the timestamp of the last update, if required
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if (my $txt = ($ipv4 or $ipv6) ? $UpdateTXT : $DeleteTXT) {
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my $timestamp = localtime();
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$dnsupdate->push(update=>rr_add("$dnshost. $ttl TXT \"$txt $timestamp\""));
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}
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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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"Remote addr: ". $cgi->remote_addr . "\n".
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"IPv4 addr: ". $ipv4 . "\n".
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"IPv6 addr: ". $ipv6 . "\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 (403, "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 ($mode, $host, $dnsdomain, $debug) = @_;
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my $dnshost = expand_CNAME($host);
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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 && $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 && $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 ($mode, $host, $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, $rr->name, 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($$$$) {
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my ($mode, $host, $dnsdomain, $debug) = @_;
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my $dnshost = expand_CNAME($host);
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my $title = "DynDNS Updater - $host";
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print $cgi->header(-status=>200),
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$cgi->start_html(-title => $title),
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$cgi->h1($title);
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print $cgi->p("$host resolves to $dnshost") if($host cmp $dnshost);
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print $cgi->p("Current DNS information for $dnshost:"),
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$cgi->start_table,
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$cgi->Tr({-align=>'LEFT',-valign=>'TOP'}, [
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$cgi->th(['Field', 'Value'])
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]);
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foreach my $rr (DNS_get($dnshost)->answer) {
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if(my $label = $DNS_label{$rr->type}) {
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print $cgi->Tr([ $cgi->td([$label, DNS_decode_rr($rr)]) ]);
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}
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}
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print $cgi->end_table();
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print $cgi->end_html();
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}
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sub handle_list($$$$) {
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my ($mode, $host, $dnsdomain, $debug) = @_;
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my $title = "DynDNS Updater - $dnsdomain";
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fail("Operation not allowed", ($DomainListKey eq 'off') ? "List is disabled"
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: "No/incorrect authentication information provided", 403)
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if ($DomainListKey eq 'off') || (($DomainListKey cmp '') && ($DomainListKey cmp $cgi->param('secret')));
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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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##############################
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# Load configuration, if desired
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if ($ConfigFile cmp 'ignore') {
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my $CFGFile = $0;
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$CFGFile =~ s/(\.pl)?$/.cfg/;
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if (open (CONFIG, $CFGFile)) {
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my %CONFIG = (
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allow_debug_key => \$AllowDebugKey, domain_list_key => \$DomainListKey,
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dns_server => \$DNSServer, dns_domain => \@DNSDomain,
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expand_cnames => \$ExpandCNAMEs, auth_mode => \$AuthMode,
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static_signer => \$StaticSigner, static_key => \$StaticKey,
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require_rr => \$RequireRR, replace_rr => \@ReplaceRR,
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update_txt => \$UpdateTXT, delete_txt => \$DeleteTXT,
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expire_after => \$ExpireAfter, record_ttl => \$RecordTTL,
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);
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while (<CONFIG>) {
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chomp; s/^\s+//; s/\s*(#.*)?$//; # trim whitespace & comments
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next unless length; # skip empty lines
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my ($key, $value) = split(/\s*=\s*/, $_, 2); # split key and value
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my $dst = $CONFIG{$key}; # get destination for value
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if (ref $dst eq 'SCALAR') { $$dst = $value; } # store scalar value
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elsif (ref $dst eq 'CODE') { &$dst($value); } # call setter function
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elsif (ref $dst cmp 'ARRAY') { fail($SE, "Invalid config: $key"); }
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else { @$dst = split(/\s*,\s*/, $value); } # split and store array
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}
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close CONFIG;
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} elsif ($ConfigFile eq 'required') {
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fail($SE, "unable to load configuration from $CFGFile: $!");
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}
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}
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##############################
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# Validate Configuration
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fail($CE, "ConfigFile must be optional, required or ignore, not '$ConfigFile'")
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unless $ConfigFile=~/optional|required|ignore/;
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fail($CE, "AuthMode '$AuthMode' is unsupported must be remote, static or both")
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unless $AuthMode=~/remote|static|both/;
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fail($CE, "StaticSigner must be set for \$AuthMode '$AuthMode'")
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unless ($StaticSigner or $AuthMode eq 'remote');
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fail($CE, "StaticKey must be set for \$AuthMode '$AuthMode'")
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unless ($StaticKey or $AuthMode eq 'remote');
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fail($CE, "RequireRR is set to unsupported type '$RequireRR'")
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if ($RequireRR and not $DNS_label{$RequireRR});
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fail($CE, "RecordTTL '$RecordTTL' is not supported")
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unless ($RecordTTL=~/^\d+[smhw]?$/);
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fail($CE, "ExpireAfter '$ExpireAfter' is not supported")
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unless ($ExpireAfter=~/^\d+[smhw]?$/);
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fail($CE, "UpdateTXT must be set when \$ExpireAfter is set")
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if($ExpireAfter and not $UpdateTXT);
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foreach my $rrtype (@ReplaceRR) {
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fail($CE, "ReplaceRR contains unsupported type '$rrtype'")
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unless exists $DNS_label{$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 $dnsdomain;
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foreach my $d (@DNSDomain) {
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if ($d eq '!') { $d = $cgi->virtual_host; }
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elsif ($d eq '?') { $d = $cgi->param('domain'); }
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elsif ($d =~ /-?\d+/) {
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if ($d <0) { $d = join('.', splice(@{[ split(/\./, $cgi->virtual_host) ]}, $d)); }
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else { $d = join('.', splice(@{[ split(/\./, $host) ]}, ($d) ? -$d : 1)); }
|
|
}
|
|
$dnsdomain = $d if (!$host || length($host) == length($d)+rindex($host,$d));
|
|
last if $dnsdomain;
|
|
}
|
|
fail($PE, "No host name to act on specified", 400)
|
|
unless $host || $mode eq 'list' || $mode eq 'expire';
|
|
fail($PE, "No host or domain name to act on specified", 400) unless $dnsdomain;
|
|
|
|
|
|
##############################
|
|
# Dispatch the request to the correct handler
|
|
my %handlers = (
|
|
view => \&handle_view,
|
|
update => \&handle_update,
|
|
delete => \&handle_update,
|
|
list => \&handle_list,
|
|
expire => \&handle_expire,
|
|
);
|
|
if(my $handler = $handlers{$mode}) {
|
|
$handler->($mode, $host, $dnsdomain, $debug);
|
|
} else {
|
|
fail("File Not Found", "Invalid Mode '$mode' specified", 404);
|
|
}
|
|
|