# The LearningOnline Network
# Switch Servers Handler
#
# $Id: switchserver.pm,v 1.63 2022/09/13 12:22:14 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/
#

package Apache::switchserver;

use strict;
use Apache::Constants qw(:common :remotehost);
use Apache::lonnet;
use Digest::MD5 qw(md5_hex);
use CGI::Cookie();
use Apache::lonlocal;
use LONCAPA qw(:DEFAULT :match);

sub init_env {
    my ($r) = @_;
    
    if (-e $env{'user.environment'}) {
	return  $env{'user.environment'};
    }
    my $requrl=$r->uri;
    my $handle= &Apache::lonnet::check_for_valid_session($r);
    if ($handle ne '') {
	return undef;
    }
    my $lonidsdir=$r->dir_config('lonIDsDir');
    &Apache::lonnet::transfer_profile_to_env($lonidsdir,$handle);

    return $r->dir_config('lonIDsDir')."/$handle.id";
}

sub do_redirect {
    my ($r,$url,$only_body,$extra_text,$write_to_opener) = @_;
    $r->send_http_header;
    my $delay = 0.5;
    if ($only_body && !$extra_text) {
        $delay = 0;
    }
    my $start_page = 
	&Apache::loncommon::start_page('Switching Server ...',undef,
				       {'redirect'       => [$delay,$url,'',$write_to_opener,1],
					'only_body'      => $only_body,});
    my $end_page   = &Apache::loncommon::end_page();
    $r->print($start_page.$extra_text.$end_page);
    unless ($env{'user.name'} eq 'public' && ($env{'user.domain'} eq 'public')) {
        $r->register_cleanup(\&flush_course_logs);
    }
    return OK;
}

sub balancer_cookieid {
    my ($r,$desthost,$uname,$udom) = @_;
    my @hosts = &Apache::lonnet::current_machine_ids();
    my $newcookieid;
    unless (grep(/^\Q$desthost\E$/,@hosts)) {
        my $balancedir=$r->dir_config('lonBalanceDir');
        $newcookieid = &md5_hex(&md5_hex(time.{}.rand().$$));
        my $cookie = $udom.'_'.$uname.'_'.$newcookieid;
        my $balcookie = "balanceID=$cookie; path=/; HttpOnly;";
        if (open(my $fh,'>',"$balancedir/$cookie.id")) {
            print $fh $desthost;
            close($fh);
            $r->headers_out->add('Set-cookie' => $balcookie);
        }
    }
    return $newcookieid;
}

sub flush_course_logs {
    &Apache::lonnet::flushcourselogs();
    return OK;
}

sub handler {
    my ($r) = @_;

    my $handle=&init_env($r);
    if (!defined($handle)) { return FORBIDDEN; }

    &Apache::loncommon::get_unprocessed_cgi($ENV{'QUERY_STRING'},
				['otherserver','role','origurl','symb','lcssowin','edit']);

    my $switch_to=&Apache::lonnet::hostname($env{'form.otherserver'});
    if (! $env{'form.otherserver'}) {
	$env{'form.otherserver'} =	
	    &Apache::lonnet::find_existing_session($env{'user.domain'},
						   $env{'user.name'});
	if (! $env{'form.otherserver'}) {
	    $env{'form.otherserver'} = 
		&Apache::lonnet::spareserver($r,30000,undef,1);
	}
	$switch_to=&Apache::lonnet::hostname($env{'form.otherserver'});
    }

    if (!defined($switch_to)) { return FORBIDDEN; }

    my $protocol = 'http';
    if ($env{'form.otherserver'}) {
        if ($Apache::lonnet::protocol{$env{'form.otherserver'}} eq 'https') {
            $protocol = $Apache::lonnet::protocol{$env{'form.otherserver'}};
        }
        unless ($env{'form.otherserver'} eq $r->dir_config('lonHostID')) {
            my $alias = &Apache::lonnet::use_proxy_alias($r,$env{'form.otherserver'});
            $switch_to = $alias if ($alias ne '');
        }
    }

    if ($env{'user.name'} eq 'public'
	&& $env{'user.domain'} eq 'public') {
	my $url = $protocol.'://'.$switch_to.$r->uri;
        unlink($handle);
        #expire the cookie
        my $c = new CGI::Cookie(-name    => 'lonPubID',
                                -value   => '',
                                -expires => '-10y',);
        $r->header_out('Set-cookie' => $c);
	return &do_redirect($r,$url,1)
    }

    my $skip_canhost_check = '';
    my $now = time;
    if ($env{'form.role'}) {
        if (!exists($env{'user.role.'.$env{'form.role'}})) {
            delete($env{'form.role'});
        } else {
            my ($start,$end) = split(/\./,$env{'user.role.'.$env{'form.role'}});
            if (($start && $start > $now) || ($end && $end < $now)) {
                delete($env{'form.role'});
            } elsif ($env{'form.role'} eq 'au./'.$env{'user.domain'}.'/') {
                if (&Apache::lonnet::homeserver($env{'user.name'},$env{'user.domain'}) eq $env{'form.otherserver'}) {
                    $skip_canhost_check = 1;
                }
            } elsif ($env{'form.role'} =~ m{^[ac]a\./($match_domain)/($match_username)$}) {
                my ($audom,$auname) = ($1,$2);
                if (&Apache::lonnet::homeserver($auname,$audom) eq $env{'form.otherserver'}) {
                    if ((&Apache::lonnet::will_trust('othcoau',$env{'user.domain'},$audom)) &&
                        (&Apache::lonnet::will_trust('coaurem',$audom,$env{'user.domain'}))) {                             
                        $skip_canhost_check = 1;
                    }
                }
            }
        }
    }

    unless ($skip_canhost_check) {
        my $canhost = &Apache::lonnet::can_switchserver($env{'user.domain'},$env{'form.otherserver'});
        unless ($canhost) {
            if (($env{'request.course.id'}) && ($env{'form.symb'} ne '') &&
                (&Apache::lonnet::allowed('mdc',$env{'request.course.id'}))) {
                my $cdom = $env{'course.'.$env{'request.course.id'}.'.domain'};
                my $cnum = $env{'course.'.$env{'request.course.id'}.'.num'};
                if (($cdom ne '') && ($cnum ne '') && ($env{'form.role'} =~ m{^([^.]+)\Q./$cdom/$cnum\E$})) {
                    my $symb = &Apache::lonnet::symbclean($env{'form.symb'});
                    my ($map,$idx,$url) = &Apache::lonnet::decode_symb($symb);
                    if (&Apache::lonnet::symbverify($symb,$url)) {
                        my $fileloc = &Apache::lonnet::declutter(&Apache::lonnet::filelocation("",$url));
                        my $resurl = &Apache::lonnet::clutter($url);
                        if ($resurl =~ m{^/res/($match_domain)/($match_username)/}) {
                            my ($audom,$auname) = ($1,$2);
                            if (&Apache::lonnet::homeserver($auname,$audom) eq $env{'form.otherserver'}) {
                                my @possroles = ("user.role.au./$audom/","user.role.ca./$audom/$auname","user.role.aa./$audom/$auname");
                                my $hasrole;
                                foreach my $rolekey (@possroles) {
                                    if (exists($env{$rolekey})) {
                                        my ($start,$end) = split(/\./,$env{$rolekey});
                                        unless (($start && $start > $now) || ($end && $end < $now)) {
                                            if ($rolekey eq "user.role.au./$audom/") {
                                                $hasrole = $rolekey;
                                            } elsif ((&Apache::lonnet::will_trust('othcoau',$env{'user.domain'},$audom)) &&
                                                     (&Apache::lonnet::will_trust('coaurem',$audom,$env{'user.domain'}))) {
                                                $hasrole = $rolekey;
                                            }
                                        }
                                        if ($hasrole) {
                                            $hasrole =~ s/^\Quser.role.\E//;
                                            last;
                                        }
                                    }
                                }
                                if ($hasrole) {
                                    $env{'form.role'} = $hasrole;
                                    $env{'form.origurl'} = &Apache::lonnet::deversion($resurl);
                                    $env{'form.origurl'} =~ s{^/res/}{/priv/};
                                    delete($env{'form.symb'});
                                    $canhost = 1;
                                    if ($env{'form.edit'}) {
                                        my $ip = &Apache::lonnet::get_requestor_ip($r,REMOTE_NOLOOKUP);
                                        my %info=('ip'            => $ip,
                                                  'domain'        => $env{'user.domain'},
                                                  'username'      => $env{'user.name'},
                                                  'home'          => $env{'user.home'},
                                                  'role'          => $env{'form.role'},
                                                  'server'        => $r->dir_config('lonHostID'),
                                                  'origurl'       => $env{'form.origurl'});
                                        &Apache::loncommon::content_type($r,'text/html');
                                        my $token = &Apache::lonnet::tmpput(\%info,$env{'form.otherserver'});
                                        my $url = $protocol.'://'.$switch_to.'/adm/login?'.
                                                                 'domain='.$env{'user.domain'}.
                                                                 '&amp;username='.$env{'user.name'}.
                                                                 '&amp;token='.$token;
                                        return &do_redirect($r,$url,0);
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
        unless ($canhost) { return FORBIDDEN; }
    }

    #remove session env, and log event
    if (unlink($handle)) {
        if ($env{'user.linkedenv'} ne '') {
            my $lonidsdir=$r->dir_config('lonIDsDir');
            if (($env{'user.linkedenv'} =~ /^[a-f0-9]+_linked$/) &&
                (-l "$lonidsdir/$env{'user.linkedenv'}.id") &&
                (readlink("$lonidsdir/$env{'user.linkedenv'}.id") eq $handle)) {
                unlink("$lonidsdir/$env{'user.linkedenv'}.id");
            }
        }
    }
    my %temp=('switchserver' => $now.':'.$env{'form.otherserver'},
	      $env{'form.role'});
    &Apache::lonnet::put('email_status',\%temp);
    my $logmsg = "Switch Server to $env{'form.otherserver'}";
    if ($env{'form.role'}) {
        $logmsg .= " with role: $env{'form.role'}";
    } elsif (($env{'form.lti.reqcrs'}) && ($env{'form.lti.reqrole'} eq 'cc')) {
        $logmsg .= " to create new LTI course";
    } elsif ($env{'form.lti.selfenrollrole'}) {
        $logmsg .= " to selfenroll with role: $env{'form.lti.selfenrollrole'}";
    } else {
        $logmsg .= " (no role)";
    }
    my $ip = &Apache::lonnet::get_requestor_ip($r,REMOTE_NOLOOKUP);
    $logmsg .= ' '.$ip;
    &Apache::lonnet::log($env{'user.domain'},$env{'user.name'},
			 $env{'user.home'},$logmsg);

    &Apache::loncommon::content_type($r,'text/html');

    #expire the cookies
    my %cookies=CGI::Cookie->parse($r->header_in('Cookie'));
    foreach my $name (keys(%cookies)) {
        next unless ($name =~ /^lon(|S|Link|Pub)ID$/);
        my $c = new CGI::Cookie(-name    => $name,
                                -value   => '',
                                -expires => '-10y',);
        $r->headers_out->add('Set-cookie' => $c);
    }
    if ($r->header_only) {
	$r->send_http_header;
	return OK;
    }
# -------------------------------------------------------- Menu script and info

# ---------------------------------------------------------------- Get handover

    my ($is_balancer,$setcookie,$newcookieid,$otherbalcookie,$offloadto,$dom_balancers);
    my $only_body = 0;
    ($is_balancer,undef,$setcookie,$offloadto,$dom_balancers) =
        &Apache::lonnet::check_loadbalancing($env{'user.name'},$env{'user.domain'},'switchserver');
    if ($is_balancer && $setcookie && $env{'form.otherserver'}) {

        # Set a balancer cookie unless browser already sent LON-CAPA load balancer
        # cookie which points at the target server
        my ($found_server,$balancer_cookie) = &Apache::lonnet::check_for_balancer_cookie($r,1);

        if (($found_server eq $env{'form.otherserver'}) &&
            ($balancer_cookie =~ /^\Q$env{'user.domain'}\E_\Q$env{'user.name'}\E_/)) {
            $only_body = 1;
        } else {
            $newcookieid = &balancer_cookieid($r,$env{'form.otherserver'},
                                              $env{'user.name'},$env{'user.domain'});
        }
    }
    if ((!$is_balancer) && ($env{'request.balancercookie'})) {
        $otherbalcookie = $env{'request.balancercookie'};
    }

    my %info=('ip'            => $ip,
              'domain'        => $env{'user.domain'},
              'username'      => $env{'user.name'},
              'home'          => $env{'user.home'},
              'role'          => $env{'form.role'},
              'server'        => $r->dir_config('lonHostID'),
              'balancer'      => $is_balancer,
              'dom_balancers' => $dom_balancers,
              'offloadto'     => '');
    if (ref($offloadto) eq 'HASH') {
        foreach my $key (keys(%{$offloadto})) {
            if (ref($offloadto->{$key}) eq 'ARRAY') {
                $info{'offloadto'} .= $key.'='.join(',',@{$offloadto->{$key}}).'&';
            }
        }
        $info{'offloadto'} =~ s/\&$//;
    } elsif (ref($offloadto) eq 'ARRAY') {
        $info{'offloadto'} = join(',',@{$offloadto});
    }
    if ($newcookieid) {
        $info{'balcookie'} = $newcookieid;
    } elsif ($otherbalcookie) {
        $info{'otherbalcookie'} = $otherbalcookie;
    }
    if ($env{'form.origurl'}) {
        $info{'origurl'} = $env{'form.origurl'};
    }
    if ($env{'form.symb'}) {
        $info{'symb'} = $env{'form.symb'};
    }
    my $ssologoutscript = '';
    my $write_to_opener;
    if ($env{'request.sso.login'}) {
	$info{'sso.login'} = $env{'request.sso.login'};
        if (defined($r->dir_config("lonSSOUserLogoutScriptFile_$info{domain}"))) {
            if (open(my $fh,'<',$r->dir_config("lonSSOUserLogoutScriptFile_$info{domain}"))) {
                $ssologoutscript .= join('',<$fh>);
                close($fh); 
            }
        }
        if (defined($r->dir_config('lonSSOUserLogoutScriptFile'))) {
            if (open(my $fh,'<',$r->dir_config('lonSSOUserLogoutScriptFile'))) {
                $ssologoutscript .= join('',<$fh>);
                close($fh);
            }
        }
    }
    if ($env{'request.sso.reloginserver'}) {
        $info{'sso.reloginserver'} = $env{'request.sso.reloginserver'};
    }
    if ($env{'request.linkprot'}) {
        $info{'linkprot'} = $env{'request.linkprot'};
        foreach my $item ('linkprotuser','linkprotexit') {
            if ($env{'request.'.$item}) {
                $info{$item} = $env{'request.'.$item};
            }
        }
    } elsif ($env{'request.linkkey'} ne '') {
        $info{'linkkey'} = $env{'request.linkkey'};
    }
    if ($env{'request.deeplink.login'}) {
        $info{'deeplink.login'} = $env{'request.deeplink.login'};
    }
    if ($env{'request.lti.login'}) {
        $info{'lti.login'} = $env{'request.lti.login'};
    }
    if ($env{'request.lti.uri'}) {
        $info{'lti.uri'} = $env{'request.lti.uri'};
    }
    if ($env{'request.lti.reqcrs'}) {
        $info{'lti.reqcrs'} = $env{'request.lti.reqcrs'};
    }
    if ($env{'request.lti.reqrole'}) {
        $info{'lti.reqrole'} = $env{'request.lti.reqrole'};
    }
    if ($env{'request.lti.selfenrollrole'}) {
        $info{'lti.selfenrollrole'} = $env{'request.lti.selfenrollrole'};
    }
    if ($env{'request.lti.sourcecrs'}) {
        $info{'lti.sourcecrs'} = $env{'request.lti.sourcecrs'};
    }
    if ($env{'request.lti.passbackid'}) {
        $info{'lti.passbackid'} = $env{'request.lti.passbackid'};
    }
    if ($env{'request.lti.passbackurl'}) {
        $info{'lti.passbackurl'} = $env{'request.lti.passbackurl'};
    }
    if ($env{'request.lti.rosterid'}) {
        $info{'lti.rosterid'} = $env{'request.lti.rosterid'};
    }
    if ($env{'request.lti.rosterurl'}) {
        $info{'lti.rosterurl'} = $env{'request.lti.rosterurl'};
    }
    if ($env{'request.lti.target'}) {
        $info{'lti.target'} = $env{'request.lti.target'};
    }
    my $token = &Apache::lonnet::tmpput(\%info,$env{'form.otherserver'});
    my @args = ("domain=$env{'user.domain'}",
                "username=$env{'user.name'}",
                "token=$token");
    my $url = $protocol.'://'.$switch_to.'/adm/login?';
    if ($env{'form.lcssowin'}) {
        $url .= join('&',@args);
        $only_body = 1;
    } else {
        $url .= join('&amp;',@args);
    }
# --------------------------------------------------------------- Screen Output
    return &do_redirect($r, $url, $only_body, $ssologoutscript, $env{'form.lcssowin'});
}

1;
__END__