#!/usr/bin/perl

# CS357 ASSIGNMENT 3
# Workstation status monitor
# Dan J. Fraser (1219229)
# done in perl with permission of Jim Mullin

#name of the input file
$inputfile = 'hosts';

#path to store machine information, must end in '/'
$outpath = '/gaul/s9/student/1995/fraser1/stats/';

#open the input file, exit if we can't find it.
open(FOO,$inputfile) or die "can't open input file: ";

#ping timeout, in seconds
$timeout = 2;

#amount of time to sleep between checks
$sleep = 1800; # 1/2 hour

# -------------------------

#load the contents of the input file into an array
@machines = <FOO>;
close FOO;  # clsoe the input file

while (1) {  # loop forever
    foreach $machine (@machines) {  # for every machine on the list do...
       ($ip,$name) = split(' ',$machine);  # split the /etc/hosts format into IP and name
       if ($ip =~ /^\d+\.\d+\.\d+\.\d+$/) {  # ensure we have a valid IP
          # create/append a file for the output data
	  open(MACHINE,">>$outpath$name") or die "couldn't open machine file";
	  #now call the ping command and check the returncode
	  if (system("ping $ip $timeout >/dev/null")) { 
	     # the machine is down.  write that information to the file!
	     print "$name is down.\n";
	     print MACHINE time." down\n";
	  } else {
	     # the machine is up.  write that information to the file!
	     print "$name is up.\n";
	     print MACHINE time." up\n";
	  }
	  close MACHINE;  # close the output file
       }
   }
   print "done checking.  Waiting $sleep seconds.\n";
   sleep $sleep;  # wait for a bit.
}