#!/usr/bin/perl
use strict;

# This script is used when switching over to a backup server or
# when switching back to the master server. This script is to be
# run on the SLAVE (secondary) node!

# 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
# 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

# Copyright (C) 2003 Jani Reinikainen [ devel@reinikainen.net ]
# Version 0.2.0 (20. February 2003)

#######################################################
# These are some variables you probably want to set up.

my %services   = ("apachectl start" => "/var/run/apache.pid", "proftpd" => "/usr/local/var/proftpd.pid", "exim -bd" => "/var/spool/exim/exim-daemon.pid", "amavisd" => "/var/amavis/amavisd.pid", "apache-sslctl start" => "/var/run/apache-ssl.pid", "safe_mysqld \&" => "/var/run/mysqld/mysqld.pid");
my @rsyncpaths = ("/home","/var/mail");
my $rsync      = "/usr/bin/rsync";

# No further editing neccessary.
#######################################################


# CHECK THAT WE GOT ALL NEEDED ARGUMENTS
if ($#ARGV != 1) {
 print "Error: you need to give this script two arguments.\n";
 print "Usage: ./takeover.pl \[set/remove\] \[IP-address\]\n\n";
 exit;
}

# CHECK THAT USER IS ROOT
unless ($> == 0 || $< == 0) {
 print "Error: You must run this script as root!\n";
 print "Usage: ./takeover.pl \[set/remove\] \[IP-address\]\n\n";
 exit;
}

if (@ARGV[0] eq "set") {

 if (!-e "/etc/fake/instance_config/@ARGV[1].cfg") {
  print "Error: Fake is not configured to takeover this IP address.\n";
  print "Please edit fake\'s configuration files in /etc/fake\n\n";
  exit;
 }

 # Check that a computer with the IP to be taken over is not on the network
 # NOTE: THIS USES THE ARPING FROM THE IPUTILS PACKAGE, AND _NOT_ THE OTHER
 # (CONFLICTING!) ARPING FROM http://www.habets.pp.se/synscan/!
 if (`arping -D -q -I eth0 -c 2 @ARGV[1]; echo \$?` == 1) {
  print "The IP address @ARGV[1] exists on the network. Did you take down the interface?\n";
  print "I will not take over an existing IP address, in order to avoid conflicts.\n\n";
  exit;
 }

 # CHECK THAT SERVICES ARE RUNNING
 foreach my $key (keys %services) {

  # Check if PID file exists and is readable
   if (-e $services{$key}) {
    open(FILE,$services{$key});
    my $PID = <FILE>;
    chomp($PID);
    close FILE;

    # Check if PID found in PID file is actually running
    if (system("kill -CHLD $PID >/dev/null 2>&1")) {
     print "PID file '$services{$key}' exists, but no matching service (PID $PID) running. Trying to run '$key'.\n";
     system("$key");

    # We've got a stale PID file on our hands. Try to start the daemon.
    } else {
     print "'$key' running (PID $PID). This is good. Not starting another one.\n";
    }

   # No PID file for this daemon found. Try to start it.
   } else {
    print "PID file '$services{$key}' doesn't exist, or is not readable. Trying to run '$key'.\n";
    system("$key");
   }
 }

 # TAKEOVER THE IP
 system("fake @ARGV[1] \&");
 
 print "All done! This computer should now answer to the IP address $2\n";
 print "To remove this fake IP, run './takeover.pl remove @ARGV[1]'\n";
 print "To make sure all went as planned, here is the output of ifconfig:\n\n";
 system("ifconfig");

}


if (@ARGV[0] eq "remove") {

 print "I need to rsync the changed data back to the master server.\n";
 print "Could you tell me at which IP the master currently resides?\n";
 my $master_ip   = &promptUser("IP","Y");
 my $master_user = &promptUser("Okay. I still need to know under which username we are connecting","Y","root");

 # First (big) rsync run to master
 &showDatetime;
 print "Running first rsync run to $master_ip.\n";

 foreach my $rsyncpath (@rsyncpaths) {
  my $dirname = `dirname $rsyncpath`;
  system("$rsync -rlopgztvC --delete $rsyncpath $master_user\@$master_ip:$dirname");
 }

 &showDatetime;
 print "First rsync run to $master_ip completed.\n";
 
 # Close ProFTPd
 system("killall proftpd");
 &showDatetime;
 print "Closed ProFTPd.\n";
 
 # Close MTA
 system("killall exim");
 &showDatetime;
 print "Closed Exim.\n";
  
 # Second, small and (hopefully) fast, rsync run to master
 &showDatetime;
 print "Running second rsync run to $master_ip.\n";

 foreach my $rsyncpath (@rsyncpaths) {
  my $dirname = `dirname $rsyncpath`;
  system("$rsync -rlopgztvC --delete $rsyncpath $master_user\@$master_ip:$dirname");
 }

 &showDatetime;
 print "Second rsync run to $master_ip completed.\n"; 
 
 # REMOVE IP FAKING
 system("fake remove @ARGV[1]");
 &showDatetime;
 print "Removed IP faking.\n";
 
 print "All done! This computer should no longer answer to the IP address @ARGV[1]\n";
 print "Don't forget to start the master server!\n";
 print "To make sure all went as planned, here is the output of ifconfig:\n\n";
 system("ifconfig");



}












#  PURPOSE:	Prompt the user for some type of input, and return the
#		input back to the calling program.
#  ARGS:	$promptString - what you want to prompt the user with
#		$defaultValue - (optional) a default value for the prompt

sub promptUser {

   (my $promptString, my $notNull, my $defaultValue) = @_;

   if ($defaultValue) {
      print $promptString, " [", $defaultValue, "]: ";
   } else {
      print $promptString, ": ";
   }

   $| = 1;        # force a flush after our print
   $_ = <STDIN>;  # get the input from STDIN (presumably the keyboard)

   # Remove the newline character from the end of the input the user gave us
   chomp;

   #  if we had a $default value, and the user gave us input, then   #
   #  return the input; if we had a default, and they gave us no     #
   #  no input, return the $defaultValue.                            #

   if ("$defaultValue") {
      return $_ ? $_ : $defaultValue;    # return $_ if it has a value
   } else {

    # Check that user inputted something if we didn't have a default value
     if ($_ ne "") {
      return $_;
     } else {
      if (lc($notNull) eq "y") {
       print "Error: Not a valid input, you must input a value.\n";
       &promptUser("$promptString","Y");
      }
     }
   }
}



sub showDatetime {
 my @now = localtime();
 printf ("\[%02d/%02d/%s %02d:%02d:%02d\] ", @now[3], @now[4]+1, @now[5]+1900, @now[2], @now[1], @now[0]);
 return;
}