#!/usr/bin/perl -w
#
# external_acl helper to Squid to verify NT Domain group
# membership using wbinfo
#
# This program is put in the public domain by Jerry Murdock 
# <jmurdock@itraktech.com>. It 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.
#
# Author:
#   Jerry Murdock <jmurdock@itraktech.com>
#
# Version history:
#   2010-08-27 Hank Hampel <hh@nr-city.net>
#               Add Kerberos to NTLM conversion of credentials (-K)
#
#   2005-12-26 Guido Serassio <guido.serassio@acmeconsulting.it>
#               Add '-d' command line debugging option
#
#   2005-12-24 Guido Serassio <guido.serassio@acmeconsulting.it>
#               Fix for wbinfo from Samba 3.0.21
#
#   2004-08-15 Henrik Nordstrom <hno@squid-cache.org>
#		Helper protocol changed to URL escaped in Squid-3.0
#
#   2005-06-28 Arno Streuli <astreuli@gmail.com>
#               Add multi group check
#
#   2002-07-05 Jerry Murdock <jmurdock@itraktech.com>
#		Initial release
=pod

=head1 NAME

ext_wbinfo_group_acl - external ACL helper for Squid to verify NT Domain group membership using wbinfo.

=head1 SYNOPSIS

ext_wbinfo_group_acl [-dh]

=head1 DESCRIPTION

ext_wbinfo_group_acl is an installed executable script.
It uses wbinfo from Samba to lookup group membership of logged in users.

This helper must be used in with an authentication scheme (typically
Basic or NTLM) based on Windows NT/2000 domain users.

It reads from the standard input the domain username and a list of groups
and tries to match each against the groups membership of the specified
username.

=head1 OPTIONS

	-d Write debug info to stderr.
	-h Print the help.
	-K downgrade Kerberos credentials to NTLM.

=head1 CONFIGURATION

	external_acl_type wbinfo_check %LOGIN /path/to/ext_wbinfo_group_acl
	acl allowed_group external wbinfo_check Group1 Group2
	http_access allow allowed_group

If the local perl interpreter is in a unusual location it may need to be added:

	external_acl_type wbinfo_check %LOGIN /path/to/perl /path/to/ext_wbinfo_group_acl

=head1 AUTHOR

This program was written by Jerry Murdock <jmurdock@itraktech.com>

This manual was written by Amos Jeffries <amosjeffries@squid-cache.org>

=head1 COPYRIGHT

This program is put in the public domain by Jerry Murdock
<jmurdock@itraktech.com>. It 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.

=head1 QUESTIONS

Questions on the usage of this program can be sent to the
Squid Users mailing list <squid-users@squid-cache.org>

=head1 REPORTING BUGS

Bug reports need to be made in English.
See http://wiki.squid-cache.org/SquidFaq/BugReporting for details of what you need to include with your bug report.

Report bugs or bug fixes using http://bugs.squid-cache.org/

Report serious security bugs to Squid Bugs <squid-bugs@squid-cache.org>

Report ideas for new improvements to the
Squid Developers mailing list <squid-dev@squid-cache.org>

=head1 SEE ALSO

The Squid FAQ wiki http://wiki.squid-cache.org/SquidFaq

The Squid Configuration Manual http://www.squid-cache.org/Doc/config/

=cut

#
# Globals
#
use vars qw/ %opt /;

# Disable output buffering
$|=1;

sub debug {
	print STDERR "@_\n" if $opt{d};
}

#
# Check if a user belongs to a group
#
sub check {
        local($user, $group) = @_;
	if ($opt{K} && ($user =~ m/\@/)) {
		@tmpuser = split(/\@/, $user);
		$user = "$tmpuser[1]\\$tmpuser[0]";
	}
        $groupSID = `wbinfo -n "$group" | cut -d" " -f1`;
        chop  $groupSID;
        $groupGID = `wbinfo -Y "$groupSID"`;
        chop $groupGID;
        &debug( "User:  -$user-\nGroup: -$group-\nSID:   -$groupSID-\nGID:   -$groupGID-");
        return 'ERR' if($groupGID eq ""); # Verify if groupGID variable is empty.
        return 'ERR' if(`wbinfo -r \Q$user\E` eq ""); # Verify if "wbinfo -r" command returns no value.
        return 'OK' if(`wbinfo -r \Q$user\E` =~ /^$groupGID$/m);
        return 'ERR';
}

#
# Command line options processing
#
sub init()
{
    use Getopt::Std;
    my $opt_string = 'hdK';
    getopts( "$opt_string", \%opt ) or usage();
    usage() if $opt{h};
}

#
# Message about this program and how to use it
#
sub usage()
{
	print "Usage: ext_wbinfo_group_acl -dh\n";
	print "\t-d enable debugging\n";
	print "\t-h print the help\n";
	print "\t-K downgrade Kerberos credentials to NTLM.\n";
	exit;
}

init();
print STDERR "Debugging mode ON.\n" if $opt{d};

#
# Main loop
#
while (<STDIN>) {
        chop;
	&debug("Got $_ from squid");
        ($user, @groups) = split(/\s+/);
	$user =~ s/%([0-9a-fA-F][0-9a-fA-F])/pack("c",hex($1))/eg;
 	# test for each group squid send in it's request
 	foreach $group (@groups) {
		$group =~ s/%([0-9a-fA-F][0-9a-fA-F])/pack("c",hex($1))/eg;
 		$ans = &check($user, $group);
 		last if $ans eq "OK";
 	}
	&debug("Sending $ans to squid");
	print "$ans\n";
}
