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Bug #1320

# 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 1.55 2011/10/24 22:39:14 www 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/
#

=pod

=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

=item constructaccess($url,$setpriv)

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.
If 'setpriv' is set to 'setpriv', it actually assigns the privileges.
=back

=cut


package Apache::loncacc;

use strict;
use Apache::Constants qw(:common :http :methods REDIRECT);
use Fcntl qw(:flock);
use Apache::lonlocal;
use Apache::lonnet;
use Apache::lonacc;
use LONCAPA qw(:DEFAULT :match);

sub constructaccess {
    my ($url,$setpriv)=@_;

# We do not allow editing of previous versions of files
    if ($url=~/\.(\d+)\.(\w+)$/) { return ''; }

# Get username and domain from URL
    my ($ownerdomain,$ownername)=($url=~/^\/priv\/($match_domain)\/($match_username)\//);

# The URL does not really point to any authorspace, forget it
    unless (($ownername) && ($ownerdomain)) { return ''; }
  
# Now we need to see if the user has access to the authorspace of
# $ownername at $ownerdomain

    if (($ownername eq $env{'user.name'}) && ($ownerdomain eq $env{'user.domain'})) {
# Real author for this?
       if (exists($env{'user.priv.au./'.$ownerdomain.'/./'})) {
          return ($ownername,$ownerdomain);
       }
    } else {
# Co-author for this?
	if (exists($env{'user.priv.ca./'.$ownerdomain.'/'.$ownername.'./'}) ||
	    exists($env{'user.priv.aa./'.$ownerdomain.'/'.$ownername.'./'}) ) {
	    return ($ownername,$ownerdomain);
	}
    }
# We don't have any access right now. If we are not possibly going to do anything about this,
# we might as well leave
   unless ($setpriv) { return ''; }

# Backdoor access?
    my $allowed=&Apache::lonnet::allowed('eco',$ownerdomain);
# Nope
    unless ($allowed) { return ''; }
# Looks like we may have access, but could be locked by the owner of the construction space
    if ($allowed eq 'U') {
        my %blocked=&Apache::lonnet::get('environment',['domcoord.author'],
                                         $ownerdomain,$ownername);
# Is blocked by owner
        if ($blocked{'domcoord.author'} eq 'blocked') { return ''; }
    }
    if (($allowed eq 'F') || ($allowed eq 'U')) {
# Grant temporary access
        my $then=$env{'user.login.time'};
        my $update==$env{'user.update.time'};
        if (!$update) { $update = $then; }
        my $refresh=$env{'user.refresh.time'};
        if (!$refresh) { $refresh = $update; }
        my $now = time;
        &Apache::lonnet::check_adhoc_privs($ownerdomain,$ownername,
                                           $update,$refresh,$now,'ca',
                                           'constructaccess');
        return($ownername,$ownerdomain);
    }
# No business here
    return '';
}

sub handler {
    my $r = shift;
    my $requrl=$r->uri;
    $env{'request.editurl'}=$requrl;

    my $handle =  &Apache::lonnet::check_for_valid_session($r);
    if ($handle ne '') {

# ------------------------------------------------------ Initialize Environment
        my $lonidsdir=$r->dir_config('lonIDsDir');
	&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,'setpriv')) {
	    $r->log_reason("Unauthorized $requrl", $r->filename); 
	    return HTTP_NOT_ACCEPTABLE;
	}

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

	&Apache::lonacc::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__