#!/usr/bin/perl
#############################################################################

#############################################################################
#                                                                           #
# File:  sign                                                               #
#                                                                           #
# Usage: sign [-c] file.sig [base directory]                                #
#                                                                           #
# Description:                                                              #
#        Used to MD5 sign files                                             #
#                                                                           #
# Options:                                                                  #
#        -c    Creates signature file                                       #
#                                                                           #
#############################################################################
#                                                                           #
# (C) 2001 Stefano Selleri                                                  #
#                                                                           #
# Vers. 0.0.0                                                               #
#                                                                           #
#############################################################################

$CRCFunc = "/usr/bin/md5sum";

#############################################################################
# &Help;                                                                    #
# This routine explains brief usage syntax to STDOUT. The program is then   #
#  terminated.                                                              #
#############################################################################
#
sub Help {
  print "Usage:\tsign [-c] file.sig [directory]\n";
  print "\tUsed to sign and verify file signatures.\n\n";
  print "\tOptions:\n";
  print "\t-c\tCreates signature file.\n";
  print "\n\nP.S., have you extracted the POD?\n\n";
  exit;
}


#############################################################################
# &getdir (root, recursiveFlag);                                            #
# Routine to gather filenames within a directory, with an optional recursive#
# flag.                                                                     #
#############################################################################
#
sub getdir {
  local($rootdir)=@_;
  print "scanning -> $rootdir\n";
  opendir(DIR, $rootdir) || die "No can do...\n";
  foreach (sort readdir(DIR))
    {
      next if (/^\.\.?$/);
      $filename = $_;
      $filename = "$rootdir/$filename";

      # root directory gets a double slash prepended so we clean it up.
      $filename =~ s/\/\//\//;

      if (!-d $filename)
	{
	  # User wants to use the systems better CRC/hash functions.
	  if ( !open(IN,"$CRCFunc '$filename' |") )
	    {
	      printf("Unable to read $CRCFunc or $filename for CRC generation.\n");
	      exit;
	    }

	  # Get the return value of the CRC/hash function in $filecrc
	  $filecrc = <IN>;

	  chomp($filecrc);
	  close(IN);

	  ($filecrc)=split(" ", $filecrc);

	  $SIGS{$filename}=$filecrc;
	}

      if ((-d "$filename" && !-l "$filename")) { &getdir("$filename"); }
    }
  close(DIR);
}


#############################################################################
# Main routine begins.                                                      #
#############################################################################
#

if(@ARGV<1) { &Help; } # Help the user with the syntax

if ($ARGV[0] eq "-c") {$create=1;shift @ARGV;}

$sigfile = $ARGV[0] || die "No sig file\n";
shift @ARGV;

if (-f $sigfile && $create) {
  die "$sigfile exists\n";
}

if ((! -f $sigfile) && (! $create)) {
  die "$sigfile do not exist";
}

$root = $ARGV[0];
if (! defined $root) {$root = "/"}

&getdir($root);

if ($create) {
  open (FH,">$sigfile");
  foreach $a (keys(%SIGS)) {
    print FH "$a $SIGS{$a}\n";
  }
  close (FH);
} else {
  open (FH,"<$sigfile");
  while (<FH>) {
    chomp();
    ($file,$sig)=split(" ");
    if ($SIGS{$file} ne $sig) {
      print "WARNING: file $file does NOT match\n";
    }
    delete $SIGS{$file};
  }
  close (FH);

  foreach $a (keys(%SIGS)) {
    print "Found NEW file $a not in $sigfile\n";
  }
}

__END__

=head1 NAME

sign.pl - recursively generates, stores and checkes
MD5 signatures

=head1 SUPPORTED PLATFORMS

Any with perl B<and> md5sum or any other
signature generator

=head1 SYNOPSIS

  sign.pl -c file.sig directory 

Recursively scans C<directory> generating
an MD5 signature of each file found herein.
Everithing is stored in a file named
C<file.sig>.

  sign.pl file.sig directory 

Recursively scans C<directory> generating
an MD5 signature of each file found herein.
Result is checked against C<file.sig>. Warnings
are issued if signature does not match,
if a filed not in C<file.sig> is present or
if a file in C<file.sig> has disappeared.

  sign.pl -h

A little help

=head1 USAGE

Wat's this for?

Well, have you ever heard of hackers? they sometimes
break in, change some executables and do what they please...

BUT

If you generate C<file.sig> of the sensitive directories,
that is C</bin> C</sbin> etc. etc. and store the files
on a floppy somewhere else then you can check, at
regular intervals, if something evil has happened.

=head1 REVISION HISTORY

Hey! this is version 0.0.0! Do you B<really> think
that there is an history at all?

=head1 CREDITS

B<sign.pl> has been developed by

I<Stefano Selleri>

I<Department of Electronics and Telecommunications>
I<University of Florence>
I<Via C. Lombroso 6/17>
I<50134 Firenze Italy.>

The author can be contacted at I<selleri@ingfi9.det.unifi.it>
and the latest version of the B<sign.pl> code should be
located at I<http://florence.pm.org/>

=head1 License

B<quiz.pl> and related files

(C) 2001 Stefano Selleri

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 (at your option) 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