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- Use token to store role, symb, linkprot, and/or linkkey when dual log-in
  page to support SSO (Shibboleth) and non-SSO is in use, and for "log in
  again" retry link for failed login, instead of using query string directly.
- When digest is used by tmpput handler in lond to generate an id, only use
  id which does not already exist in LON-CAPA's tmp directory.

# The LearningOnline Network
# Redirect Shibboleth authentication to designated URL (/adm/sso).
#
# $Id: lonshibauth.pm,v 1.11 2021/10/26 15:52:54 raeburn 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/
#

=head1 NAME

Apache::lonshibauth - Redirect Shibboleth authentication

=head1 SYNOPSIS

Invoked when lonOtherAuthen is set to yes, and type is Shibboleth 

If server is configured as a Shibboleth SP, the main Apache 
configuration file, e.g.,  /etc/httpd/conf/httpd.conf
(for RHEL/CentOS/Scentific Linux/Fedora) should contain:

LoadModule mod_shib /usr/lib/shibboleth/mod_shib_22.so

or equivalent (depending on Apache version) 
before the line to include conf/loncapa_apache.conf

=head1 INTRODUCTION

Redirects a user requiring Single Sign On via Shibboleth to a  
URL -- /adm/sso -- on the server which is configured to use that service.

=head1 HANDLER SUBROUTINE

This routine is called by Apache and mod_perl.

=over 4

If $r->user defined and requested uri not /adm/sso
redirect to /adm/sso

Otherwise return DECLINED

=back

=cut

package Apache::lonshibauth;

use strict;
use lib '/home/httpd/lib/perl/';
use Apache::lonnet;
use Apache::loncommon;
use Apache::lonacc;
use Apache::Constants qw(:common REDIRECT);
use LONCAPA qw(:DEFAULT :match);

sub handler {
    my $r = shift;
    my $target = '/adm/sso';
    if (&Apache::lonnet::get_saml_landing()) {
        $target = '/adm/login';
    }
    if (($r->user eq '') && ($r->uri ne $target) && ($r->uri ne '/adm/sso')) {
        my $lonhost = $Apache::lonnet::perlvar{'lonHostID'};
        my $hostname = &Apache::lonnet::hostname($lonhost);
        if (!$hostname) { $hostname = $r->hostname(); }
        my $protocol = $Apache::lonnet::protocol{$lonhost};
        unless ($protocol eq 'https') { $protocol = 'http'; }
        my $alias = &Apache::lonnet::use_proxy_alias($r,$lonhost);
        if (($alias ne '') &&
            (&Apache::lonnet::alias_shibboleth($lonhost))) {
            $hostname = $alias;
        }
        my $dest = $protocol.'://'.$hostname.$target;
        if ($target eq '/adm/login') {
             my $querystring = &set_token($r,$lonhost);
             if ($querystring ne '') {
                 $dest .= '?'.$querystring;
             }
        } else {
            my $uri = $r->uri;
            if ($r->args ne '') {
                $dest .= (($dest=~/\?/)?'&':'?').$r->args;
            }
            unless (($uri eq '/adm/roles') || ($uri eq '/adm/logout')) {
                unless ($r->args =~ /origurl=/) {
                    $dest.=(($dest=~/\?/)?'&':'?').'origurl='.$uri;
                }
            }
            if ($uri =~ m{^/tiny/$match_domain/\w+$}) {
                unless (($r->args =~ /ltoken=/) || ($r->args =~ /linkkey=/)) {
                    &Apache::lonacc::get_posted_cgi($r,['linkkey']);
                    if ($env{'form.linkkey'} ne '') {
                        $dest.=(($dest=~/\?/)?'&':'?').'linkkey='.$env{'form.linkkey'};
                    }
                }
            }
        }
        $r->header_out(Location => $dest);
        return REDIRECT;
    } else {
        return DECLINED;
    }
}

sub set_token {
    my ($r,$lonhost) = @_;
    my ($firsturl,$querystring,$ssotoken,@names,%token);
    @names = ('role','symb','ltoken','linkkey');
    map { $token{$_} = 1; } @names;
    unless (($r->uri eq '/adm/roles') || ($r->uri eq '/adm/logout')) {
        $firsturl = $r->uri;
    }
    if ($r->args ne '') {
        &Apache::loncommon::get_unprocessed_cgi($r->args);
    }
    if ($r->uri =~ m{^/tiny/$match_domain/\w+$}) {
        unless (($env{'form.ltoken'}) || ($env{'form.linkkey'})) {
            &Apache::lonacc::get_posted_cgi($r,['linkkey']);
        }
    }
    my $extras;
    foreach my $name (@names) {
        if ($env{'form.'.$name} ne '') {
            if ($name eq 'ltoken') {
                my %info = &Apache::lonnet::tmpget($env{'form.ltoken'});
                if ($info{'linkprot'}) {
                    $extras .= '&linkprot='.&escape($info{'linkprot'});
                    last;
                }
            } else {
                $extras .= '&'.$name.'='.&escape($env{'form.'.$name});
            }
        }
    }
    if (($firsturl ne '') || ($extras ne '')) {
        $extras .= ':sso';
        $ssotoken = &Apache::lonnet::reply('tmpput:'.&escape($firsturl).
                                           $extras,$lonhost);
        $querystring = 'sso='.$ssotoken;
    }
    if ($r->args ne '') {
        foreach my $key (sort(keys(%env))) {
            if ($key =~ /^form\.(.+)$/) {
                my $name = $1;
                next if ($token{$name});
                $querystring .= '&'.$name.'='.$env{$key};
            }
        }
    }
    return $querystring;
}

1;
__END__