# chSvcRunner.pl changes account an NT service runs as on remote machines via the registry.
# Written 8-mar-2000 by fgb.
# usage: chSvcRunner /service=svcname /runas=acctname [machinelist.fil]
#
# Notes:
# -----
# Add code to check existing account and only change if it's not localSystem
# (or user-supplied account name)?
#
# Nothin' but perl, baby!

require "ctime.pl";
use Net::Ping;
use Win32::Registry;

# evil globals:

$bDebug = 0;
$sAppName = "chSvcRunner";
$sDate = &ctime(time); chop $sDate;
$sLocalMachine = Win32::NodeName;
$sMachine = "";
$sMachineList = "";
$sNow = time();
$sRunAs = "";
$sService = "";
$nTotalMachines = 0;
$bVerbose = 0;
$sVersion = "1.0";

MAIN:

ParseCmdArgs();
if (($sRunAs eq "") || ($sService eq "")) { print "Missing or invalid syntax\n"; Help(); exit; }

print "$sAppName $sVersion starting at $sDate...\n";
if ($sMachineList eq "") { 
  if (! $bSingleMachine) {
    $sMachine = $sLocalMachine;
    print "No list supplied; trashing local machine.\n";	# arf
    exit;
    }
  if (-1 != &ChRunner()) { ++$nTotalMachines; }
  }
else { 
  open(FPCLIST,$sMachineList) || die "Can't open file $sMachineList: $!\n";

  while (<FPCLIST>) {
    if (!/^\!/) {						# skip comments
      chop $_;
      s/\s(.*)//;						# remove whitespace
      s/^\\\\//;						# remove leading '\\'
      $sMachine = $_;
      if (&IsVisibleOnNet()) {
        if (-1 != &ChRunner()) { ++$nTotalMachines; }
        }
      }
    }
  close(FPCLIST);
  }
print "\n$sAppName: updated $sService service on $nTotalMachines machine";
if ($nTotalMachines != 1) { print "s."; }
exit;

# subroutines:

sub ChRunner {					### incomplete ***
  local $sKey = "";
  local $sBaseKey = "SYSTEM\\CurrentControlSet\\Services";
  local $sValName = "ObjectName";
  local $hk;
  local $hkr;
  local @subkeys = ();
  local $pSubkeys = \@subkeys;			# reference (ptr) to subkeys list

  $sServer = "\\\\" . $sMachine;		# used by Connect()
  print "Updating $sMachine...";

  $HKR = $main::HKEY_LOCAL_MACHINE;
  unless ($HKR->Connect($sServer,$hkr)) {
    print "Can't connect to $sServer; Win95?\n";
    return -1;
    }

  $sKey = $sBaseKey . '\\' . $sService;
  if (!$hkr->Open($sKey,$hk)) { print "error opening key $sKey\n"; return; }
  if ($bDebug) { print "dbg: SetValueEx($sValName,0,REG_SZ,$sRunAs)\n"; }
  else { 
    if (!$hk->SetValueEx($sValName,0,REG_SZ,$sRunAs)) { 
      if ($bVerbose) { print "error setting value for $sValName\n"; }
      }
    else { print "Set $sValName for $sKey\n"; }
    }
  $hk->Close();
  $hkr->Close();
  }

sub Help {
  printf("%s version %s\n",$sAppName,$sVersion);
  printf("\nusage: %s /service= /runas= [machinelist.fil]\n\n",$sAppName);
  print "service= value must be name as it appears in NET START listing\n";
  print "runas= value is account name; if domain account, format is DOMAIN\Username\n";
  }

sub IsVisibleOnNet {
  $p = Net::Ping->new("icmp");
  return ($p->ping($sMachine,1));
}

sub ParseCmdArgs {
  unless ($#ARGV + 1) { Help(); exit; }
  while (@ARGV) {
    $_ = shift @ARGV;
    if ($bDebug) {
      print "dbg: parsing $_\n";
      }
    if (/^[\/\-]/) {				# is arg a switch?
      $arg = substr($_,1,3);			# parse 1st 3 chars:

      if (($arg eq "hel") || (substr($arg,0,1) eq "?")) {
        &Help();
	exit;
        }
      if ($arg eq "ser") {
        $i = index($_,"=");
        $i++;
        $sService = sprintf("%s",substr($_,$i));
        }
      if ($arg eq "run") {
        $i = index($_,"=");
        $i++;
        $sRunAs = sprintf("%s",substr($_,$i));
        }
      }
    else {					# not a switch
      if (/^[\\]/) {				# single machine (UNC)
        s/\s(.*)//;				# remove whitespace
        s/^\\\\//;				# remove leading \\
        $sMachine = $_;
        $bSingleMachine = 1;
        }
      else { $sMachineList = $_; }
      }
    }
  }