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#!/usr/bin/perl
# dynamic-dnsmasq.pl - update dnsmasq's internal dns entries dynamically
# Copyright (C) 2004 Peter Willis
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# 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
#
# the purpose of this script is to be able to update dnsmasq's dns
# records from a remote dynamic dns client.
#
# basic use of this script:
# dynamic-dnsmasq.pl add testaccount 1234 testaccount.mydomain.com
# dynamic-dnsmasq.pl listen &
#
# this script tries to emulate DynDNS.org's dynamic dns service, so
# technically you should be able to use any DynDNS.org client to
# update the records here. tested and confirmed to work with ddnsu
# 1.3.1. just point the client's host to the IP of this machine,
# port 9020, and include the hostname, user and pass, and it should
# work.
#
# make sure "addn-hosts=/etc/dyndns-hosts" is in your /etc/dnsmasq.conf
# file and "nopoll" is commented out.
use strict;
use IO::Socket;
use MIME::Base64;
use DB_File;
use Fcntl;
my $accountdb = "accounts.db";
my $recordfile = "/etc/dyndns-hosts";
my $dnsmasqpidfile = "/var/run/dnsmasq.pid"; # if this doesn't exist, will look for process in /proc
my $listenaddress = "0.0.0.0";
my $listenport = 9020;
# no editing past this point should be necessary
if ( @ARGV < 1 ) {
die "Usage: $0 ADD|DEL|LISTUSERS|WRITEHOSTSFILE|LISTEN\n";
} elsif ( lc $ARGV[0] eq "add" ) {
die "Usage: $0 ADD USER PASS HOSTNAME\n" unless @ARGV == 4;
add_acct($ARGV[1], $ARGV[2], $ARGV[3]);
} elsif ( lc $ARGV[0] eq "del" ) {
die "Usage: $0 DEL USER\n" unless @ARGV == 2;
print "Are you sure you want to delete user \"$ARGV[1]\"? [N/y] ";
my $resp = <STDIN>;
chomp $resp;
if ( lc substr($resp,0,1) eq "y" ) {
del_acct($ARGV[1]);
}
} elsif ( lc $ARGV[0] eq "listusers" or lc $ARGV[0] eq "writehostsfile" ) {
my $X = tie my %h, "DB_File", $accountdb, O_RDWR|O_CREAT, 0600, $DB_HASH;
my $fh;
if ( lc $ARGV[0] eq "writehostsfile" ) {
open($fh, ">$recordfile") || die "Couldn't open recordfile \"$recordfile\": $!\n";
flock($fh, 2);
seek($fh, 0, 0);
truncate($fh, 0);
}
while ( my ($key, $val) = each %h ) {
my ($pass, $domain, $ip) = split("\t",$val);
if ( lc $ARGV[0] eq "listusers" ) {
print "user $key, hostname $domain, ip $ip\n";
} else {
if ( defined $ip ) {
print $fh "$ip\t$domain\n";
}
}
}
if ( lc $ARGV[0] eq "writehostsfile" ) {
flock($fh, 8);
close($fh);
dnsmasq_rescan_configs();
}
undef $X;
untie %h;
} elsif ( lc $ARGV[0] eq "listen" ) {
listen_for_updates();
}
sub listen_for_updates {
my $sock = IO::Socket::INET->new(Listen => 5,
LocalAddr => $listenaddress, LocalPort => $listenport,
Proto => 'tcp', ReuseAddr => 1,
MultiHomed => 1) || die "Could not open listening socket: $!\n";
$SIG{'CHLD'} = 'IGNORE';
while ( my $client = $sock->accept() ) {
my $p = fork();
if ( $p != 0 ) {
next;
}
$SIG{'CHLD'} = 'DEFAULT';
my @headers;
my %cgi;
while ( <$client> ) {
s/(\r|\n)//g;
last if $_ eq "";
push @headers, $_;
}
foreach my $header (@headers) {
if ( $header =~ /^GET \/nic\/update\?([^\s].+) HTTP\/1\.[01]$/ ) {
foreach my $element (split('&', $1)) {
$cgi{(split '=', $element)[0]} = (split '=', $element)[1];
}
} elsif ( $header =~ /^Authorization: basic (.+)$/ ) {
unless ( defined $cgi{'hostname'} ) {
print_http_response($client, undef, "badsys");
exit(1);
}
if ( !exists $cgi{'myip'} ) {
$cgi{'myip'} = $client->peerhost();
}
my ($user,$pass) = split ":", MIME::Base64::decode($1);
if ( authorize($user, $pass, $cgi{'hostname'}, $cgi{'myip'}) == 0 ) {
print_http_response($client, $cgi{'myip'}, "good");
update_dns(\%cgi);
} else {
print_http_response($client, undef, "badauth");
exit(1);
}
last;
}
}
exit(0);
}
return(0);
}
sub add_acct {
my ($user, $pass, $hostname) = @_;
my $X = tie my %h, "DB_File", $accountdb, O_RDWR|O_CREAT, 0600, $DB_HASH;
$X->put($user, join("\t", ($pass, $hostname)));
undef $X;
untie %h;
}
sub del_acct {
my ($user, $pass, $hostname) = @_;
my $X = tie my %h, "DB_File", $accountdb, O_RDWR|O_CREAT, 0600, $DB_HASH;
$X->del($user);
undef $X;
untie %h;
}
sub authorize {
my $user = shift;
my $pass = shift;
my $hostname = shift;
my $ip = shift;;
my $X = tie my %h, "DB_File", $accountdb, O_RDWR|O_CREAT, 0600, $DB_HASH;
my ($spass, $shost) = split("\t", $h{$user});
if ( defined $h{$user} and ($spass eq $pass) and ($shost eq $hostname) ) {
$X->put($user, join("\t", $spass, $shost, $ip));
undef $X;
untie %h;
return(0);
}
undef $X;
untie %h;
return(1);
}
sub print_http_response {
my $sock = shift;
my $ip = shift;
my $response = shift;
print $sock "HTTP/1.0 200 OK\n";
my @tmp = split /\s+/, scalar gmtime();
print $sock "Date: $tmp[0], $tmp[2] $tmp[1] $tmp[4] $tmp[3] GMT\n";
print $sock "Server: Peter's Fake DynDNS.org Server/1.0\n";
print $sock "Content-Type: text/plain; charset=ISO-8859-1\n";
print $sock "Connection: close\n";
print $sock "Transfer-Encoding: chunked\n";
print $sock "\n";
#print $sock "12\n"; # this was part of the dyndns response but i'm not sure what it is
print $sock "$response", defined($ip)? " $ip" : "" . "\n";
}
sub update_dns {
my $hashref = shift;
my @records;
my $found = 0;
# update the addn-hosts file
open(FILE, "+<$recordfile") || die "Couldn't open recordfile \"$recordfile\": $!\n";
flock(FILE, 2);
while ( <FILE> ) {
if ( /^(\d+\.\d+\.\d+\.\d+)\s+$$hashref{'hostname'}\n$/si ) {
if ( $1 ne $$hashref{'myip'} ) {
push @records, "$$hashref{'myip'}\t$$hashref{'hostname'}\n";
$found = 1;
}
} else {
push @records, $_;
}
}
unless ( $found ) {
push @records, "$$hashref{'myip'}\t$$hashref{'hostname'}\n";
}
sysseek(FILE, 0, 0);
truncate(FILE, 0);
syswrite(FILE, join("", @records));
flock(FILE, 8);
close(FILE);
dnsmasq_rescan_configs();
return(0);
}
sub dnsmasq_rescan_configs {
# send the HUP signal to dnsmasq
if ( -r $dnsmasqpidfile ) {
open(PID,"<$dnsmasqpidfile") || die "Could not open PID file \"$dnsmasqpidfile\": $!\n";
my $pid = <PID>;
close(PID);
chomp $pid;
if ( kill(0, $pid) ) {
kill(1, $pid);
} else {
goto LOOKFORDNSMASQ;
}
} else {
LOOKFORDNSMASQ:
opendir(DIR,"/proc") || die "Couldn't opendir /proc: $!\n";
my @dirs = grep(/^\d+$/, readdir(DIR));
closedir(DIR);
foreach my $process (@dirs) {
if ( open(FILE,"</proc/$process/cmdline") ) {
my $cmdline = <FILE>;
close(FILE);
if ( (split(/\0/,$cmdline))[0] =~ /dnsmasq/ ) {
kill(1, $process);
}
}
}
}
return(0);
}
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