Subversion Repositories sysadmin_scripts

#! /usr/bin/env perl

use warnings;

use strict;

use Sys::Syslog;

use version

our $VERSION = version->declare( '2.0.0' );

#  Copyright (c) 2021, R. W. Rodolico

#  

#  Redistribution and use in source and binary forms, with or without 

#  modification, are permitted provided that the following conditions

#  are met:

#

#      Redistributions of source code must retain the above copyright

#      notice, this list of conditions and the following disclaimer.

#      

#      Redistributions in binary form must reproduce the above 

#      copyright notice, this list of conditions and the following 

#      disclaimer in the documentation and/or other materials provided

#      with the distribution.

#

#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 

#  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 

#  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 

#  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 

#  COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,

#  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,

#  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 

#  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 

#  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

#  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 

#  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 

#  POSSIBILITY OF SUCH DAMAGE.[9] 

# called as an ssh command

# ssh my_server hostname [ip]

# where hostname is the host name to be processed

# if IP is not given, will take the source IP from the ssh connection

# Can also be called from command line as

# ./updatedns hostname ip

# version 2.0.0

# 20210417 RWR

# major modification to use one script for local and remote

# also, added ability to set up a configuration file

# we'll store the configuration here, so we can load it easily from

# a config file, if it exists

my %configuration = (

   'local'  => 1,

   'domain' => '',

   'server' => '',

   'keyfile' => '',

   'ttl' => 3600

   );

######################################################

# you should not have to change anything below here. #

######################################################

# get script path so we can find the auxiliary files

use Cwd qw(abs_path);

use File::Basename;

my $appDir = dirname(abs_path(__FILE__)) . '/';

my $statusFile = $appDir . 'updatedns.status'; # stores current status of known entries

my $template = $appDir . 'updatedns.template'; # a template used for commands to nsupdate

# If local set, use -l parameter, otherwise, use the key file

my $nsupdate = '/usr/bin/nsupdate ' . ( $configuration{'local'} ? '-l ' : " -k $configuration{keyfile} " );

my $configFile = $appDir . 'updatedns.conf';

my $hostname;

my $realIP;

my %entries;

# prepend 'server ' to the server command if it exists and we are not local

$configuration{'server'} = "server $configuration{'server'}" if $configuration{'server'} and not $configuration{'local'};

# this reads an INI type file in the form 

# key:value

# where : is any delimiter

# it then merges it into %$hash, overwriting anything with the same

# key with a new value

sub readFile {

   my %temp;

   my ($filename,$hash,$delimiter ) = @_;

   $delimiter = ':' unless $delimiter;

   return unless -f $filename;

   open CONF,"<$filename" or die "Could not read existing configuration file $filename: $!\n";

   # turn the delimited file into a hash

   chomp( %temp = map { split $delimiter } grep{ !/^#/ } my (@a) = <CONF> );

   close CONF;

   # merge into existing hash, leaving items not common alone

   @$hash{keys %temp} = values %temp;

}

# merge the template file with our values and save it to a file

# in /tmp/hostname.nsupdate (overwriting if necessary)

# Call nsupdate with the filename as a parameter.

# leaves the file in /tmp for debugging

sub doUpdateNS {

   my ($hostname, $ip) = @_;

   my $nsupdateFileName = "/tmp/$hostname.nsupdate";

   # grab the template

   open TEMPLATE, "<$template" or die "could not open template $template for read: $!\n";

   my $template = join( '', <TEMPLATE> );

   close TEMPLATE;

   # now, replace our keys with our current values

   $template =~ s/\{hostname\}/$hostname/gi;

   $template =~ s/\{server\}/$configuration{'server'}/gi;

   $template =~ s/\{zone\}/$configuration{'domain'}/gi;

   $template =~ s/\{ttl\}/$configuration{'ttl'}/gi;

   $template =~ s/\{ip\}/$ip/gi;

   # save the file

   open OUTPUT, ">$nsupdateFileName" or die "Could not create $nsupdateFileName: $!\n";

   print OUTPUT $template;

   close OUTPUT;

   # execute nsupdate, and return the results to the caller

   return `$nsupdate $nsupdateFileName`;

}

&readFile( $configFile, \%configuration, '=' );

#foreach my $key ( sort keys %configuration ) {

#   print "$key\t$configuration{$key}\n";

#}

#die;

# user should send hostname as a parameter on the command

# user may also send the IP

if ( defined $ENV{'SSH_ORIGINAL_COMMAND'} ) {

   ($hostname,$realIP) = split( ' ', $ENV{'SSH_ORIGINAL_COMMAND'});

   $realIP = $ENV{'SSH_CLIENT'} unless $realIP;

} else {

   $hostname = shift;

   $realIP = shift;

}

die "Invalid call\n" unless $hostname and $realIP;

# validate IP is valid IPv4

# NOT a very good regex for that, but ... 

$realIP =~ m/^([\d.]+)/;

$realIP = $1;

#die "$hostname\t$realIP\n";

# Start logging to syslog

openlog('updatedns', 'cons,pid', 'user');

unless ( $hostname ) {

   syslog( 'FATAL','%s',"no hostname passed in from IP $realIP" );

   die "Invalid Invocation: hostname\n" ;

}

# validate the hostname is part of the $domain

if ( $hostname !~ m/[a-z0-9-]\.$configuration{'domain'}/ ) {

   syslog( 'warning', '%s', "Attempt to set incoming server name to invalid host [$hostname]");

   exit;

}

# slup in the status file

&readFile( $statusFile,\%entries, "\t" );

# is the entry for $hostname alread set? Do nothing except log it

if ( ( exists $entries{$hostname} ) && ( $entries{$hostname} eq $realIP ) ) {

   print "$configuration{'domain'}: Already set to the correct IP: [$realIP]\n";

   syslog('info', '%s', "Already set to the correct IP, [$hostname] = [$realIP]");

} else { # we have a new IP, or possibly a new hostname, so set it

   $entries{$hostname} = $realIP;

   open STATUS, ">$statusFile" or die "could not open $statusFile: $!\n";

   foreach my $key ( keys %entries ) {

      print STATUS "$key\t$entries{$key}\n";

   } # foreach

   my $output = &doUpdateNS( $hostname, $realIP );

   print "$hostname updated to $realIP, results are\n$output\n";

   syslog('info', '%s', "$hostname updated to $realIP" );

}

closelog();

1;