# The LearningOnline Network
# Access Handler for File Transfers
#
# $Id: lonracc.pm,v 1.10 2003/05/27 18:31:31 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/
#
# (lonacc: Cookie Based Access Handler
# 5/21/99,5/22,5/29,5/31,6/15 Gerd Kortemeyer)
# 6/16,6/18,7/3,
# 6/30/00 Gerd Kortemeyer

package Apache::lonracc;

use strict;
use Apache::Constants qw(:common :remotehost);
use Apache::lonnet();
use Apache::File();

sub subscribed {
    my ($filename,$id) = @_;
    my $found=0;
    my $expr='^'.$id.':'.$Apache::lonnet::hostip{$id}.':';
    $expr =~ s/\./\\\./g;
    my $sh;
    if ($sh=Apache::File->new("$filename.subscription")) {
	while (my $subline=<$sh>) { if ($subline =~ /$expr/) { $found=1; } }
	$sh->close();
    }
    return $found;
}

sub handler {
    my $r = shift;
    my $reqhost = $r->get_remote_host(REMOTE_DOUBLE_REV);
    if (!$reqhost && $r->get_remote_host(REMOTE_NOLOOKUP) eq $r->get_server_name()) { 
        $reqhost = $r->get_server_name();
    } 
    unless ($reqhost) {
       $r->log_reason("Spoof request from ".$ENV{'REMOTE_ADDR'});
       return FORBIDDEN;
    }
    my $readline;
    my $lontabdir=$r->dir_config('lonTabDir');
    {
       my $fh;
       unless ($fh=Apache::File->new("$lontabdir/hosts.tab")) {
          $r->log_reason("Could not find host tab file");
          return FORBIDDEN;
       }
       my $return;
       my @ids=();
       while ($readline=<$fh>) {
          my ($id,$domain,$role,$name,$ip)=split(/:/,$readline);
          if ($name =~ /$reqhost/i) {
              my $filename=$r->filename;
              if ((-e "$filename.$id") ||
		  &subscribed($filename,$id) ||
		  ($filename=~/\.meta$/)) {
	         return OK;
              } else {
                 $return=FORBIDDEN;
		 push(@ids,$id);
              }
          }
       }
       if ($return == FORBIDDEN) {
	   $r->log_reason(join(':',@ids)." not subscribed", $r->filename);
	   return FORBIDDEN;
       }
    }
    $r->log_reason("Invalid request for file transfer from $reqhost", 
                   $r->filename); 
    return FORBIDDEN;
}

1;
__END__

=head1 NAME

Apache::lonracc - Access Handler for File Transfers

=head1 SYNOPSIS

Invoked by /etc/httpd/conf/loncapa.conf:

 <LocationMatch "^/raw.*">
 PerlAccessHandler Apache::lonracc
 </LocationMatch>

=head1 INTRODUCTION

This module enables authentication for file transfers and works
against the /res tree.

Only lond invokes the /raw namespace through its subscribe function.

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 *

Determine requesting host

=item *

See whether or not the requesting host is subscribed.

=item *

Respond with status of request and make log entry in case of unallowed
access.

=back

=cut