#! /usr/bin/env perl

use strict;
use warnings;

# change following to be a list of 1 or more iSCSI targets to be queried
my @servers = ( '10.10.10.10','10.10.10.9' ); 
my %targets;


foreach my $server ( @servers ) {
   print "\n" . '-'x40 . "\nGetting targets on server $server\n" . '-'x40 . "\n";
   my @list = `iscsiadm -m discovery -t st -p $server`;
   chomp @list;
   # @list contains lines of type
   # 10.19.209.2:3260,1 iqn.2014-11.net.dailydata.castor:simon0
   # split them apart and add them to the hash
   foreach my $entry ( @list ) {
      my ( $portal, $targetName ) = split( ' ', $entry );
      # $portal has some extra info after a comma, so clean it up
      $portal =~ m/^([0-9:.]+)/;
      $portal = $1;
      # some targets return multiple IP's for a given name, so 
      # only add them if they are in this IP
      $targets{ $targetName } = $portal if $portal =~ m/^$server/;
      print "$targetName\t$targets{ $targetName }\n";
   }
}

print "\n" . '-'x40 . "\nGetting active sessions\n". '-'x40 . "\n";
# now, get active sessions so we can filter them
my @activeSessions = `iscsiadm -m session`;
chomp @activeSessions;
foreach my $session ( @activeSessions ) {
   $session =~ m/^.*[^0-9:.]([0-9,:.]+).*(iqn\S*)/;
   my ( $portal,$targetName ) = ( $1,$2 );
   print "$portal\t$targetName";
   if ( exists( $targets{$targetName} ) ) {
      print "\tNOT updating\n";
      delete $targets{ $targetName };
   } else {
      print "Needs to be added\n";
   }
}

# check if we have any new entries and bail if not
if ( scalar keys %targets ) {
   # We have new entries, so run them;
   foreach my $targetName ( sort keys %targets ) {
      my $portal = $targets{$targetName};
      print "Adding $targetName\n";
      `iscsiadm -m node --targetname '$targetName' --portal '$portal' --login`;
   }
} else {
   print "No new entries\n";
}
# print `ls /dev/disk/by-path/`;