# The LearningOnline Network
# Cookie Based Access Handler for Construction Area
# (lonacc: 5/21/99,5/22,5/29,5/31 Gerd Kortemeyer)
#
# $Id: loncacc.pm,v 1.40 2005/07/12 07:00:28 albertel Exp $
#
# Copyright Michigan State University Board of Trustees
#
# This file is part of the LearningOnline Network with CAPA (LON-CAPA).
#
# LON-CAPA 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.
#
# LON-CAPA 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 LON-CAPA; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# /home/httpd/html/adm/gpl.txt
#
# http://www.lon-capa.org/
#

package Apache::loncacc;

use strict;
use Apache::Constants qw(:common :http :methods REDIRECT);
use Apache::File;
use CGI::Cookie();
use Fcntl qw(:flock);
use Apache::lonlocal;
use Apache::lonnet;


sub constructaccess {
    my ($url,$ownerdomain)=@_;
    my ($ownername)=($url=~/\/(?:\~|priv\/|home\/)(\w+)\//);
    unless (($ownername) && ($ownerdomain)) { return ''; }
    # We do not allow editing of previous versions of files.
    if ($url=~/\.(\d+)\.(\w+)$/) { return ''; }
    my @possibledomains = &Apache::lonnet::current_machine_domains();
    if ($ownername eq $env{'user.name'}) {
	foreach my $domain (@possibledomains) {
	    if ($domain eq $env{'user.domain'}) {
		return ($ownername,$domain);
	    }
	}
    }
    
    foreach my $domain (@possibledomains) {
	if (exists($env{'user.priv.ca./'.$domain.'/'.$ownername.'./'}) ||
	    exists($env{'user.priv.aa./'.$domain.'/'.$ownername.'./'}) ) {
	    return ($ownername,$domain);
	}
    }
    return '';
}

sub handler {
    my $r = shift;
    my $requrl=$r->uri;
    $env{'request.editurl'}=$requrl;
    my %cookies=CGI::Cookie->parse($r->header_in('Cookie'));
    my $lonid=$cookies{'lonID'};
    my $cookie;
    if ($lonid) {
	my $handle=$lonid->value;
        $handle=~s/\W//g;
        my $lonidsdir=$r->dir_config('lonIDsDir');
        if ((-e "$lonidsdir/$handle.id") && ($handle ne '')) {

# ------------------------------------------------------ Initialize Environment

            &Apache::lonnet::transfer_profile_to_env($lonidsdir,$handle);

# --------------------------------------------------------- Initialize Language
 
 	    &Apache::lonlocal::get_language_handle($r);

# -------------------------------------------------------------- Resource State

            $env{'request.state'}    = "construct";
            $env{'request.filename'} = $r->filename;

            unless (&constructaccess($requrl,$r->dir_config('lonDefDomain'))) {
                $r->log_reason("Unauthorized $requrl", $r->filename); 
	        return HTTP_NOT_ACCEPTABLE;
            }

# -------------------------------------------------------- Load POST parameters

	    &Apache::loncommon::get_posted_cgi($r);

            return OK; 
        } else { 
            $r->log_reason("Cookie $handle not valid", $r->filename) 
        };
    }

# ----------------------------------------------- Store where they wanted to go

    $env{'request.firsturl'}=$requrl;
    return FORBIDDEN;
}

1;
__END__

=head1 NAME

Apache::lonacc - Cookie Based Access Handler for Construction Area

=head1 SYNOPSIS

Invoked (for various locations) by /etc/httpd/conf/loncapa_apache.conf:

 PerlAccessHandler       Apache::loncacc

=head1 INTRODUCTION

This module enables cookie based authentication for construction area
and is used to control access for three (essentially equivalent) URIs.

 <LocationMatch "^/priv.*">
 <LocationMatch "^/\~.*">
 <LocationMatch "^/\~.*/$">

Whenever the client sends the cookie back to the server, 
if the cookie is missing or invalid, the user is re-challenged
for login information.

This is part of the LearningOnline Network with CAPA project
described at http://www.lon-capa.org.

=head1 HANDLER SUBROUTINE

This routine is called by Apache and mod_perl.

=over 4

=item *

load POST parameters

=item *

store where they wanted to go (first url entered)

=back

=head1 OTHERSUBROUTINES

=over 4

=item *

constructaccess($url,$ownerdomain) : See if the owner domain and name
in the URL match those in the expected environment.  If so, return 
two element list ($ownername,$ownerdomain).  Else, return null string.

=back

=cut