# The LearningOnline Network
# Cookie Based Access Handler
#
# $Id: lonacc.pm,v 1.196 2021/10/25 15:26:27 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::lonacc - Cookie Based Access Handler

=head1 SYNOPSIS

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

 PerlAccessHandler       Apache::lonacc

=head1 INTRODUCTION

This module enables cookie based authentication and is used
to control access for many different LON-CAPA URIs.

Whenever the client sends the cookie back to the server, 
this cookie is handled by either lonacc.pm or loncacc.pm
(see srm.conf for what is invoked when).  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 *

transfer profile into environment

=item *

load POST parameters

=item *

check access

=item *

if allowed, get symb, log, generate course statistics if applicable

=item *

otherwise return error

=item *

see if public resource

=item *

store attempted access

=back

=head1 NOTABLE SUBROUTINES

=cut


package Apache::lonacc;

use strict;
use Apache::Constants qw(:common :http :methods);
use Apache::File;
use Apache::lonnet;
use Apache::loncommon();
use Apache::lonlocal;
use Apache::restrictedaccess();
use Apache::blockedaccess();
use Apache::lonprotected();
use Fcntl qw(:flock);
use LONCAPA qw(:DEFAULT :match);

sub cleanup {
    my ($r)=@_;
    if (! $r->is_initial_req()) { return DECLINED; }
    &Apache::lonnet::save_cache();
    return OK;
}

sub goodbye {
    my ($r)=@_;
    &Apache::lonnet::goodbye();
    return DONE;
}

###############################################

sub get_posted_cgi {
    my ($r,$fields) = @_;

    my $buffer;
    if ($r->header_in('Content-length')) {
	$r->read($buffer,$r->header_in('Content-length'),0);
    }
    my $content_type = $r->header_in('Content-type');
    if ($content_type !~ m{^multipart/form-data}) {
	my @pairs=split(/&/,$buffer);
	my $pair;
	foreach $pair (@pairs) {
	    my ($name,$value) = split(/=/,$pair);
	    $value =~ tr/+/ /;
	    $value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
	    $name  =~ tr/+/ /;
	    $name  =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
            if (ref($fields) eq 'ARRAY') {
                next if (!grep(/^\Q$name\E$/,@{$fields}));
            }
	    &Apache::loncommon::add_to_env("form.$name",$value);
	}
    } else {
	my ($contentsep) = ($content_type =~ /boundary=\"?([^\";,]+)\"?/);
	my @lines = split (/\n/,$buffer);
	my $name='';
	my $value='';
	my $fname='';
	my $fmime='';
	my $i;
	for ($i=0;$i<=$#lines;$i++) {
	    if ($lines[$i]=~/^--\Q$contentsep\E/) {
		if ($name) {
                    chomp($value);
                    if (($r->uri eq '/adm/portfolio') && 
                        ($name eq 'uploaddoc')) {
                        if (length($value) == 1) {
                            $value=~s/[\r\n]$//;
                        }
                    } elsif ($fname =~ /\.(xls|doc|ppt)(x|m)$/i) {
                        $value=~s/[\r\n]$//;
                    }
                    if (ref($fields) eq 'ARRAY') {
                        next if (!grep(/^\Q$name\E$/,@{$fields}));
                    }
                    if ($fname) {
                        if ($env{'form.symb'} ne '') {
                            my $size = (length($value))/(1024.0 * 1024.0);
                            if (&upload_size_allowed($name,$size,$fname) eq 'ok') {
                                $env{"form.$name.filename"}=$fname;
                                $env{"form.$name.mimetype"}=$fmime;
                                &Apache::loncommon::add_to_env("form.$name",$value);
                            }
                        } else {
                            $env{"form.$name.filename"}=$fname;
                            $env{"form.$name.mimetype"}=$fmime;
                            &Apache::loncommon::add_to_env("form.$name",$value);
                        }
                    } else {
                        $value=~s/\s+$//s;
                        &Apache::loncommon::add_to_env("form.$name",$value);
                    }
		}
		if ($i<$#lines) {
		    $i++;
		    $lines[$i]=~
		/Content\-Disposition\:\s*form\-data\;\s*name\=\"([^\"]+)\"/i;
		    $name=$1;
		    $value='';
		    if ($lines[$i]=~/filename\=\"([^\"]+)\"/i) {
			$fname=$1;
			if 
                            ($lines[$i+1]=~/Content\-Type\:\s*([\w\-\/]+)/i) {
				$fmime=$1;
				$i++;
			    } else {
				$fmime='';
			    }
		    } else {
			$fname='';
			$fmime='';
		    }
                    if ($i<$#lines && $lines[$i+1]=~/^Content\-Type\:\s*([\w\-\/]+)/i) {
                        # TODO: something with $1 !
                        $i++;
                    }
                    if ($i<$#lines && $lines[$i+1]=~/^Content\-transfer\-encoding\:\s*([\w\-\/]+)/i) {
                        # TODO: something with $1 !
                        $i++;
                    }
		    $i++;
		}
	    } else {
		$value.=$lines[$i]."\n";
	    }
	}
    }
#
# Digested POSTed values
#
# Remember the way this was originally done (GET or POST)
#
    $env{'request.method'}=$ENV{'REQUEST_METHOD'};
#
# There may also be stuff in the query string
# Tell subsequent handlers that this was GET, not POST, so they can access query string.
# Also, unset POSTed content length to cover all tracks.
#

    $r->method_number(M_GET);

    $r->method('GET');
    $r->headers_in->unset('Content-length');
}

=pod

=over

=item upload_size_allowed()

	Perform size checks for file uploads to essayresponse items in course context.
	
	Add form.HWFILESIZE.$part_$id to %env with file size (MB)
	If file exceeds maximum allowed size, add form.HWFILETOOBIG.$part_$id to %env.

=cut
 
sub upload_size_allowed {
    my ($name,$size,$fname) = @_;
    if ($name =~ /^HWFILE(\w+)$/) {
        my $ident = $1;
        my $item = 'HWFILESIZE'.$ident;
        my $savesize = sprintf("%.6f",$size);
        &Apache::loncommon::add_to_env("form.$item",$savesize);
        my $maxsize= &Apache::lonnet::EXT("resource.$ident.maxfilesize");
        if (!$maxsize) {
            $maxsize = 10.0; # FIXME This should become a domain configuration.
        }
        if ($size > $maxsize) {
            my $warn = 'HWFILETOOBIG'.$ident;
            &Apache::loncommon::add_to_env("form.$warn",$fname);
            return;
        }
    }
    return 'ok';
}

=pod

=item sso_login()

	handle the case of the single sign on user, at this point $r->user 
	will be set and valid; now need to find the loncapa user info, and possibly
	balance them. If $r->user() is set this means either it was either set by
        SSO or by checkauthen.pm, if a valid cookie was found. The latter case can
        be identified by the third arg ($usename), except when lonacc is called in 
        an internal redirect to /adm/switchserver (e.g., load-balancing following
        successful authentication) -- no cookie set yet.  For that particular case
        simply skip the call to sso_login(). 

	returns OK if it was SSO and user was handled.
        returns undef if not SSO or no means to handle the user.
        
=cut

sub sso_login {
    my ($r,$handle,$username) = @_;

    if (($r->user eq '') || ($username ne '') || ($r->user eq 'public:public') ||
        (defined($env{'user.name'}) && (defined($env{'user.domain'}))
	  && ($handle ne ''))) {
	# not an SSO case or already logged in
	return undef;
    }

    my ($user) = ($r->user =~ m/^($match_username)$/);
    if ($user eq '') {
        return undef;
    }

    my $query = $r->args;
    my %form;
    if ($query) {
        my @items = ('role','symb','iptoken','origurl','ltoken','linkkey');
        &Apache::loncommon::get_unprocessed_cgi($query,\@items);
        foreach my $item (@items) {
            if (defined($env{'form.'.$item})) {
                $form{$item} = $env{'form.'.$item};
            }
        }
    }

    my %sessiondata;
    if ($form{'iptoken'}) {
        %sessiondata = &Apache::lonnet::tmpget($form{'iptoken'});
        my $delete = &Apache::lonnet::tmpdel($form{'iptoken'});
        unless ($sessiondata{'sessionserver'}) {
            delete($form{'iptoken'});
        }
    }

    my ($linkprot,$linkkey);
    if ($form{'ltoken'}) {
        my %link_info = &Apache::lonnet::tmpget($form{'ltoken'});
        $linkprot = $link_info{'linkprot'};
        my $delete = &Apache::lonnet::tmpdel($form{'ltoken'});
    }
    if ($form{'linkkey'} ne '') {
        $linkkey = $form{'linkkey'};
    }

    my $domain = $r->dir_config('lonSSOUserDomain');
    if ($domain eq '') {
        $domain = $r->dir_config('lonDefDomain');
    }
    my $home=&Apache::lonnet::homeserver($user,$domain);
    if ($home !~ /(con_lost|no_host|no_such_host)/) {
	&Apache::lonnet::logthis(" SSO authorized user $user ");
        my ($is_balancer,$otherserver,$hosthere);
        if ($form{'iptoken'}) {
            if (($sessiondata{'domain'} eq $domain) &&
                ($sessiondata{'username'} eq $user)) {
                $hosthere = 1;
            }
        }
        unless ($hosthere) {
            ($is_balancer,$otherserver) =
                &Apache::lonnet::check_loadbalancing($user,$domain,'login');
            if ($is_balancer) {
                # Check if browser sent a LON-CAPA load balancer cookie (and this is a balancer)
                my ($found_server,$balancer_cookie) = &Apache::lonnet::check_for_balancer_cookie($r);
                if (($found_server) && ($balancer_cookie =~ /^\Q$domain\E_\Q$user\E_/)) {
                    $otherserver = $found_server;
                } elsif ($otherserver eq '') {
                    my $lowest_load;
                    ($otherserver,undef,undef,undef,$lowest_load) = &Apache::lonnet::choose_server($domain);
                    if ($lowest_load > 100) {
                        $otherserver = &Apache::lonnet::spareserver($r,$lowest_load,$lowest_load,1,$domain);
                    }
                    if ($otherserver ne '') {
                        my @hosts = &Apache::lonnet::current_machine_ids();
                        if (grep(/^\Q$otherserver\E$/,@hosts)) {
                            $hosthere = $otherserver;
                        }
                    }
                }
            }
        }
	if (($is_balancer) && (!$hosthere)) {
	    # login but immediately go to switch server to find us a new 
	    # machine
	    &Apache::lonauth::success($r,$user,$domain,$home,'noredirect');
            foreach my $item (keys(%form)) {
                $env{'form.'.$item} = $form{$item};
            }
            unless (($form{'symb'}) || ($form{'origurl'})) {
                unless (($r->uri eq '/adm/roles') || ($r->uri eq '/adm/sso')) {
                    $env{'form.origurl'} = $r->uri;
                }
            }
            if (($r->uri eq '/adm/sso') && ($form{'origurl'} =~ m{^/+tiny/+$match_domain/+\w+$})) {
                $env{'request.deeplink.login'} = $form{'origurl'};
            } elsif ($r->uri =~ m{^/+tiny/+$match_domain/+\w+$}) {
                $env{'request.deeplink.login'} = $r->uri;
            }
            if ($env{'request.deeplink.login'}) {
                if ($linkprot) {
                    $env{'request.linkprot'} = $linkprot);
                } elsif ($linkkey ne '') {
                    $env{'request.linkkey'} = $linkkey);
                }
            }
            $env{'request.sso.login'} = 1;
            if (defined($r->dir_config("lonSSOReloginServer"))) {
                $env{'request.sso.reloginserver'} =
                    $r->dir_config('lonSSOReloginServer');
            }
            my $redirecturl = '/adm/switchserver';
            if ($otherserver ne '') {
                $redirecturl .= '?otherserver='.$otherserver;
            }
	    $r->internal_redirect($redirecturl);
	    $r->set_handlers('PerlHandler'=> undef);
	} else {
	    # need to login them in, so generate the need data that
	    # migrate expects to do login
	    my $ip = &Apache::lonnet::get_requestor_ip($r);
	    my %info=('ip'        => $ip,
		      'domain'    => $domain,
		      'username'  => $user,
		      'server'    => $r->dir_config('lonHostID'),
		      'sso.login' => 1
		      );
            foreach my $item ('role','symb','iptoken','origurl') {
                if (exists($form{$item})) {
                    $info{$item} = $form{$item};
                }
            }
            unless (($info{'symb'}) || ($info{'origurl'})) {
                unless (($r->uri eq '/adm/roles') || ($r->uri eq '/adm/sso')) {
                    $info{'origurl'} = $r->uri; 
                }
            }
            if (($r->uri eq '/adm/sso') && ($form{'origurl'} =~ m{^/+tiny/+$match_domain/+\w+$})) {
                $info{'deeplink.login'} = $form{'origurl'};
            } elsif ($r->uri =~ m{^/+tiny/+$match_domain/+\w+$}) {
                $info{'deeplink.login'} = $r->uri;
            }
            if ($info{'deeplink.login'}) {
                if ($linkprot) {
                    $info{'linkprot'} = $linkprot;
                } elsif ($linkkey ne '') {
                    $info{'linkkey'} = $linkkey;
                }
            }
            if ($r->dir_config("ssodirecturl") == 1) {
                $info{'origurl'} = $r->uri;
            }
            if (defined($r->dir_config("lonSSOReloginServer"))) {
                $info{'sso.reloginserver'} = 
                    $r->dir_config('lonSSOReloginServer'); 
            }
            if (($is_balancer) && ($hosthere)) {
                $info{'noloadbalance'} = $hosthere;
            }
	    my $token = 
		&Apache::lonnet::tmpput(\%info,
					$r->dir_config('lonHostID'));
	    $env{'form.token'} = $token;
	    $r->internal_redirect('/adm/migrateuser');
	    $r->set_handlers('PerlHandler'=> undef);
	}
	return OK;
    } else {
	&Apache::lonnet::logthis(" SSO authorized unknown user $user ");
        my @cancreate;
        my %domconfig =
            &Apache::lonnet::get_dom('configuration',['usercreation'],$domain);
        if (ref($domconfig{'usercreation'}) eq 'HASH') {
            if (ref($domconfig{'usercreation'}{'cancreate'}) eq 'HASH') {
                if (ref($domconfig{'usercreation'}{'cancreate'}{'selfcreate'}) eq 'ARRAY') {
                    @cancreate = @{$domconfig{'usercreation'}{'cancreate'}{'selfcreate'}};
                } elsif (($domconfig{'usercreation'}{'cancreate'}{'selfcreate'} ne 'none') && 
                         ($domconfig{'usercreation'}{'cancreate'}{'selfcreate'} ne '')) {
                    @cancreate = ($domconfig{'usercreation'}{'cancreate'}{'selfcreate'});
                }
            }
        }
        if ((grep(/^sso$/,@cancreate)) || (defined($r->dir_config('lonSSOUserUnknownRedirect')))) {
            $r->subprocess_env->set('SSOUserUnknown' => $user);
            $r->subprocess_env->set('SSOUserDomain' => $domain);
            if (grep(/^sso$/,@cancreate)) {
                $r->set_handlers('PerlHandler'=> [\&Apache::createaccount::handler]);
                $r->handler('perl-script');
            } else {
	        $r->internal_redirect($r->dir_config('lonSSOUserUnknownRedirect'));
                $r->set_handlers('PerlHandler'=> undef);
            }
	    return OK;
        }
    }
    return undef;
}

sub handler {
    my $r = shift;
    my $requrl=$r->uri;

    if ($requrl =~ m{^/res/adm/pages/[^/]+\.(gif|png)$}) {
        return OK;
    }

    if (&Apache::lonnet::is_domainimage($requrl)) {
        return OK;
    }

    my %user;
    my $handle = &Apache::lonnet::check_for_valid_session($r,undef,\%user);

    unless (($requrl eq '/adm/switchserver') && (!$r->is_initial_req())) {
        my $result = &sso_login($r,$handle,$user{'name'});
        if (defined($result)) {
	    return $result;
        }
    }

    my ($is_balancer,$otherserver);

    if ($handle eq '') {
        unless ((($requrl eq '/adm/switchserver') && (!$r->is_initial_req())) ||
                ($requrl =~ m{^/public/$match_domain/$match_courseid/syllabus}) ||
                ($requrl =~ m{^/adm/help/}) || ($requrl eq '/adm/sso') ||
                ($requrl =~ m{^/res/$match_domain/$match_username/})) {
	    $r->log_reason("Cookie not valid", $r->filename);
        }
    } elsif ($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);

    }

# -------------------------------------------------- Should be a valid user now
    if ($env{'user.name'} ne '' && $env{'user.domain'} ne '') {
# -------------------------------------------------------------- Resource State

        my ($cdom,$cnum);
        if ($env{'request.course.id'}) {
            $cdom = $env{'course.'.$env{'request.course.id'}.'.domain'};
            $cnum = $env{'course.'.$env{'request.course.id'}.'.num'};
        }
	if ($requrl=~/^\/+(res|uploaded)\//) {
	    $env{'request.state'} = "published";
	} else {
	    $env{'request.state'} = 'unknown';
	}
	$env{'request.filename'} = $r->filename;
	$env{'request.noversionuri'} = &Apache::lonnet::deversion($requrl);
        my ($suppext,$checkabsolute);
        if ($requrl =~ m{^/adm/wrapper/ext/}) {
            my $query = $r->args;
            if ($query) {
                my $preserved;
                foreach my $pair (split(/&/,$query)) {
                    my ($name, $value) = split(/=/,$pair);
                    unless (($name eq 'symb') || ($name eq 'usehttp')) {
                        $preserved .= $pair.'&';
                    }
                    if (($env{'request.course.id'}) && ($name eq 'folderpath')) {
                        if ($value =~ /^supplemental/) {
                            $suppext = 1;
                        }
                    }
                }
                $preserved =~ s/\&$//;
                if ($preserved) {
                    $env{'request.external.querystring'} = $preserved;
                }
            }
            if ($env{'request.course.id'}) {
                $checkabsolute = 1;
            }
        } elsif ($env{'request.course.id'} &&
                 (($requrl =~ m{^/adm/$match_domain/$match_username/aboutme$}) ||
                  ($requrl eq "/public/$cdom/$cnum/syllabus") ||
                  ($requrl =~ m{^/adm/$cdom/$cnum/\d+/ext\.tool$}))) {
            my $query = $r->args;
            if ($query) {
                foreach my $pair (split(/&/,$query)) {
                    my ($name, $value) = split(/=/,$pair);
                    if ($name eq 'folderpath') {
                        if ($value =~ /^supplemental/) {
                            $suppext = 1;
                        }
                        last;
                    }
                }
            }
            if ($requrl =~ m{^/public/$cdom/$cnum/syllabus$}) {
                $checkabsolute = 1;
            }
        }
        if ($checkabsolute) {
            my $hostname = $r->hostname();
            my $lonhost = &Apache::lonnet::host_from_dns($hostname);
            if ($lonhost) {
                my $actual = &Apache::lonnet::absolute_url($hostname,1,1);
                my $exphostname = &Apache::lonnet::hostname($lonhost);
                my $expected = $Apache::lonnet::protocol{$lonhost}.'://'.$hostname;
                unless ($actual eq $expected) {
                    $env{'request.use_absolute'} = $expected;
                }
            }
        }
# -------------------------------------------------------- Load POST parameters

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

# ------------------------------------------------------ Check if load balancer 

        my $checkexempt;
        if ($env{'user.loadbalexempt'} eq $r->dir_config('lonHostID')) {
            if ($env{'user.loadbalcheck.time'} + 600 > time) {
                $checkexempt = 1;
            }
        }
        if ($env{'user.noloadbalance'} eq $r->dir_config('lonHostID')) {
            $checkexempt = 1;
        }
        unless (($checkexempt) || (($requrl eq '/adm/switchserver') && (!$r->is_initial_req()))) {
            ($is_balancer,$otherserver) =
                &Apache::lonnet::check_loadbalancing($env{'user.name'},
                                                     $env{'user.domain'});
            if ($is_balancer) {
                # Check if browser sent a LON-CAPA load balancer cookie (and this is a balancer)
                my ($found_server,$balancer_cookie) = &Apache::lonnet::check_for_balancer_cookie($r);
                if (($found_server) && ($balancer_cookie =~ /^\Q$env{'user.domain'}\E_\Q$env{'user.name'}\E_/)) {
                    $otherserver = $found_server;
                }
                unless ($requrl eq '/adm/switchserver') { 
                    $r->set_handlers('PerlResponseHandler'=>
                                     [\&Apache::switchserver::handler]);
                }
                if ($otherserver ne '') {
                    $env{'form.otherserver'} = $otherserver;
                }
                unless (($env{'form.origurl'}) || ($r->uri eq '/adm/roles') ||
                        ($r->uri eq '/adm/switchserver') || ($r->uri eq '/adm/sso')) {
                    $env{'form.origurl'} = $r->uri;
                }
            }
        }
        if ($requrl=~m{^/+tiny/+$match_domain/+\w+$}) {
            if ($env{'user.name'} eq 'public' &&
                $env{'user.domain'} eq 'public') {
                $env{'request.firsturl'}=$requrl;
                return FORBIDDEN;
            } else {
                return OK;
            }
        }
# ---------------------------------------------------------------- Check access
	my $now = time;
        my ($check_symb,$check_access,$check_block,$access,$poss_symb);
	if ($requrl !~ m{^/(?:adm|public|(?:prt|zip)spool)/}
	    || $requrl =~ /^\/adm\/.*\/(smppg|bulletinboard)(\?|$ )/x) {
            $check_access = 1;
        }
        if ((!$check_access) && ($env{'request.course.id'})) {
            if (($requrl eq '/adm/viewclasslist') ||
                ($requrl =~ m{^(/adm/wrapper|)\Q/uploaded/$cdom/$cnum/docs/\E}) ||
                ($requrl =~ m{^/adm/.*/aboutme$}) ||
                ($requrl=~m{^/adm/coursedocs/showdoc/}) ||
                ($requrl=~m{^(/adm/wrapper|)/adm/$cdom/$cnum/\d+/ext\.tool$})) {
                $check_block = 1;
            }
        }
        if (($env{'request.course.id'}) && (!$suppext)) {
            $requrl=~/\.(\w+)$/;
            if ((&Apache::loncommon::fileembstyle($1) eq 'ssi') ||
                ($requrl=~/^\/adm\/.*\/(aboutme|smppg|bulletinboard)(\?|$ )/x) ||
                ($requrl=~/^\/adm\/wrapper\//) ||
                ($requrl=~m|^/adm/coursedocs/showdoc/|) ||
                ($requrl=~m|\.problem/smpedit$|) ||
                ($requrl=~/^\/public\/.*\/syllabus$/) ||
                ($requrl=~/^\/adm\/(viewclasslist|navmaps)$/) ||
                ($requrl=~/^\/adm\/.*\/aboutme\/portfolio(\?|$)/) ||
                ($requrl=~m{^/adm/$cdom/$cnum/\d+/ext\.tool$})) {
                $check_symb = 1;
            }
        }
        if (($check_access) || ($check_block)) {
            if ($check_symb) {
                if ($env{'form.symb'}) {
                    $poss_symb=&Apache::lonnet::symbclean($env{'form.symb'});
                } elsif (($env{'request.course.id'}) && ($r->args ne '')) {
                    my $query = $r->args;
                    foreach my $pair (split(/&/,$query)) {
                        my ($name, $value) = split(/=/,$pair);
                        $name = &unescape($name);
                        $value =~ tr/+/ /;
                        $value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
                        if ($name eq 'symb') {
                            $poss_symb = &Apache::lonnet::symbclean($value);
                            last;
                        }
                    }
                }
                if ($poss_symb) {
                    my ($possmap,$resid,$url)=&Apache::lonnet::decode_symb($poss_symb);
                    $url = &Apache::lonnet::clutter($url);
                    my $toplevelmap = $env{'course.'.$env{'request.course.id'}.'.url'};
                    unless (($url eq $requrl) && (($possmap eq $toplevelmap) ||
                                                  (&Apache::lonnet::is_on_map($possmap)))) {
                        undef($poss_symb);
                    }
                    if ($poss_symb) {
                        if ((!$env{'request.role.adv'}) && ($env{'acc.randomout'}) &&
                            ($env{'acc.randomout'}=~/\&\Q$poss_symb\E\&/)) {
                            undef($poss_symb);
                        } elsif ((!$env{'request.role.adv'}) && ($env{'acc.deeplinkout'}) &&
                                 ($env{'acc.deeplinkout'}=~/\&\Q$poss_symb\E\&/)) {
                            undef($poss_symb);
                        }
                    }
                }
                if ($poss_symb) {
                    $access=&Apache::lonnet::allowed('bre',$requrl,$poss_symb);
                } else {
                    $access=&Apache::lonnet::allowed('bre',$requrl,'','','','',1);
                }
            } else {
                my $nodeeplinkcheck;
                if (($check_access) && ($requrl =~ /\.(sequence|page)$/)) {
                    unless ($env{'form.navmap'}) {
                        if ($r->args ne '') {
                            &Apache::loncommon::get_unprocessed_cgi($r->args,['navmap']);
                            unless ($env{'form.navmap'}) {
                                $nodeeplinkcheck = 1;
                            }
                        }
                    }
                }
                $access=&Apache::lonnet::allowed('bre',$requrl,'','','','','',$nodeeplinkcheck);
            }
        }
        if ($check_block) {
            if ($access eq 'B') {
                if ($poss_symb) {
                    if (&Apache::lonnet::symbverify($poss_symb,$requrl)) {
                        $env{'request.symb'} = $poss_symb;
                    }
                }
                &Apache::blockedaccess::setup_handler($r);
                return OK;
            }
        } elsif ($check_access) {
            if ($handle eq '') {
                unless ($access eq 'F') {
                    if ($requrl =~ m{^/res/$match_domain/$match_username/}) {
                        $r->log_reason("Cookie not valid", $r->filename);
                    }
                }
            }
	    if ($access eq '1') {
		$env{'user.error.msg'}="$requrl:bre:0:0:Choose Course";
		return HTTP_NOT_ACCEPTABLE; 
	    }
	    if ($access eq 'A') {
		&Apache::restrictedaccess::setup_handler($r);
		return OK;
	    }
            if ($access eq 'B') {
                if ($poss_symb) {
                    if (&Apache::lonnet::symbverify($poss_symb,$requrl)) {
                        $env{'request.symb'} = $poss_symb;
                    }
                }
                &Apache::blockedaccess::setup_handler($r);
                return OK;
            }
            if ($access eq 'D') {
                &Apache::lonprotected::setup_handler($r);
                return OK;
            }
	    if (($access ne '2') && ($access ne 'F')) {
                if ($requrl =~ m{^/res/}) {
                    $access = &Apache::lonnet::allowed('bro',$requrl);
                    if ($access ne 'F') {
                        if ($requrl eq '/res/lib/templates/simpleproblem.problem/smpedit') {
                            $access = &Apache::lonnet::allowed('bre','/res/lib/templates/simpleproblem.problem');
                            if ($access ne 'F') {
                                $env{'user.error.msg'}="$requrl:bre:1:1:Access Denied";
                                return HTTP_NOT_ACCEPTABLE;
                            }
                        } else {
                            $env{'user.error.msg'}="$requrl:bre:1:1:Access Denied";
                            return HTTP_NOT_ACCEPTABLE;
                        }
                    }
                } elsif (($handle =~ /^publicuser_\d+$/) && (&Apache::lonnet::is_portfolio_url($requrl))) {
                    my $clientip = &Apache::lonnet::get_requestor_ip($r); 
                    if (&Apache::lonnet::allowed('bre',$requrl,undef,undef,$clientip) ne 'F') {
                        $env{'user.error.msg'}="$requrl:bre:1:1:Access Denied";
                        return HTTP_NOT_ACCEPTABLE;
                    }
                } else {
		    $env{'user.error.msg'}="$requrl:bre:1:1:Access Denied";
		    return HTTP_NOT_ACCEPTABLE;
                }
	    }
	}
	if ($requrl =~ m|^/prtspool/|) {
	    my $start='/prtspool/'.$env{'user.name'}.'_'.
		$env{'user.domain'};
	    if ($requrl !~ /^\Q$start\E/) {
		$env{'user.error.msg'}="$requrl:bre:1:1:Access Denied";
		return HTTP_NOT_ACCEPTABLE;
	    }
	}
	if ($requrl =~ m|^/zipspool/|) {
	    my $start='/zipspool/zipout/'.$env{'user.name'}.":".
		$env{'user.domain'};
	    if ($requrl !~ /^\Q$start\E/) {
		$env{'user.error.msg'}="$requrl:bre:1:1:Access Denied";
		return HTTP_NOT_ACCEPTABLE;
	    }
	}
	if ($env{'user.name'} eq 'public' && 
	    $env{'user.domain'} eq 'public' &&
	    $requrl !~ m{^/+(res|public|uploaded)/} &&
	    $requrl !~ m{^/adm/[^/]+/[^/]+/aboutme/portfolio$ }x &&
            $requrl !~ m{^/adm/blockingstatus/.*$} &&
	    $requrl !~ m{^/+adm/(help|logout|restrictedaccess|randomlabel\.png)}) {
	    $env{'request.querystring'}=$r->args;
	    $env{'request.firsturl'}=$requrl;
	    return FORBIDDEN;
	}
# ------------------------------------------------------------- This is allowed
	if ($env{'request.course.id'}) {
	    &Apache::lonnet::countacc($requrl);
            my $query=$r->args;
            if ($check_symb) {
# ------------------------------------- This is serious stuff, get symb and log
		my $symb;
		if ($query) {
		    &Apache::loncommon::get_unprocessed_cgi($query,['symb','folderpath']);
		}
		if ($env{'form.symb'}) {
		    $symb=&Apache::lonnet::symbclean($env{'form.symb'});
                    if (($requrl eq '/adm/navmaps') ||
                        ($requrl =~ m{^/adm/wrapper/}) ||
                        ($requrl =~ m{^/adm/coursedocs/showdoc/})) {
                        unless (&Apache::lonnet::symbverify($symb,$requrl)) {
                            if (&Apache::lonnet::is_on_map($requrl)) {
                                $symb = &Apache::lonnet::symbread($requrl);
                                unless (&Apache::lonnet::symbverify($symb,$requrl)) {
                                    undef($symb);
                                }
                            }
                        }
                        if ($symb) {
                            if ($requrl eq '/adm/navmaps') {
                                my ($map,$mid,$murl)=&Apache::lonnet::decode_symb($symb);
                                &Apache::lonnet::symblist($map,$murl => [$murl,$mid]);
                            } elsif (($requrl =~ m{^/adm/wrapper/}) ||
                                     ($requrl =~ m{^/adm/coursedocs/showdoc/})) {
                                my ($map,$mid,$murl)=&Apache::lonnet::decode_symb($symb);
                                if ($map =~ /\.page$/) {
                                    my $mapsymb = &Apache::lonnet::symbread($map);
                                    ($map,$mid,$murl)=&Apache::lonnet::decode_symb($mapsymb); 
                                }
                                &Apache::lonnet::symblist($map,$murl => [$murl,$mid],
                                                          'last_known' =>[$murl,$mid]);
                            }
                        }
		    } elsif ((&Apache::lonnet::symbverify($symb,$requrl)) ||
			     (($requrl=~m|(.*)/smpedit$|) &&
			      &Apache::lonnet::symbverify($symb,$1)) ||
                             (($requrl=~m|(.*/aboutme)/portfolio$|) &&
                              &Apache::lonnet::symbverify($symb,$1))) {
			my ($map,$mid,$murl)=&Apache::lonnet::decode_symb($symb);
                        if (($map =~ /\.page$/) && ($requrl !~ /\.page$/)) {
                            my $mapsymb = &Apache::lonnet::symbread($map);
                            ($map,$mid,$murl)=&Apache::lonnet::decode_symb($mapsymb);
                        }
			&Apache::lonnet::symblist($map,$murl => [$murl,$mid],
						  'last_known' =>[$murl,$mid]);
		    } else {
			$r->log_reason('Invalid symb for '.$requrl.': '.
				       $symb);
			$env{'user.error.msg'}=
			    "$requrl:bre:1:1:Invalid Access";
			return HTTP_NOT_ACCEPTABLE; 
		    }
		} else {
                    if ($requrl=~m{^(/adm/.*/aboutme)/portfolio$}) {
                        $requrl = $1;
                    }
		    $symb=&Apache::lonnet::symbread($requrl);
                    if (&Apache::lonnet::is_on_map($requrl) && $symb) {
                        my ($encstate,$invalidsymb);
                        unless (&Apache::lonnet::symbverify($symb,$requrl,\$encstate)) {
                            $invalidsymb = 1;
                            #
                            # If $env{'request.enc'} inconsistent with encryption expected for $symb
                            # retrieved by lonnet::symbread(), call again to check for an instance of
                            # $requrl in the course for which expected encryption matches request.enc.
                            # If symb for different instance passes lonnet::symbverify(), use that as
                            # the symb for $requrl and call &Apache::lonnet::allowed() for that symb.
                            # Report invalid symb if there is no other symb. Redirect to /adm/ambiguous
                            # if multiple possible symbs consistent with request.enc available for $requrl.
                            #
                            if (($env{'request.enc'} && !$encstate) || (!$env{'request.enc'} && $encstate)) {
                                my %possibles;
                                my $nocache = 1;
                                my $oldsymb = $symb;
                                $symb = &Apache::lonnet::symbread($requrl,'','','',\%possibles,$nocache);
                                if (($symb) && ($symb ne $oldsymb)) {
                                    if (&Apache::lonnet::symbverify($symb,$requrl)) {
                                        my $access=&Apache::lonnet::allowed('bre',$requrl,$symb);
                                        if ($access eq 'B') {
                                            $env{'request.symb'} = $symb;
                                            &Apache::blockedaccess::setup_handler($r);
                                            return OK;
                                        } elsif (($access eq '2') || ($access eq 'F')) {
                                            $invalidsymb = '';
                                        }
                                    }
                                } elsif (keys(%possibles) > 1) {
                                    $r->internal_redirect('/adm/ambiguous');
                                    return OK;
                                }
                            }
                            if ($invalidsymb) {
                                if ($requrl eq '/adm/navmaps') {
                                    undef($symb);
                                } else {
                                    $r->log_reason('Invalid symb for '.$requrl.': '.$symb);
                                    $env{'user.error.msg'}=
                                        "$requrl:bre:1:1:Invalid Access";
                                    return HTTP_NOT_ACCEPTABLE;
                                }
                            }
                        }
                    }
		    if ($symb) {
			my ($map,$mid,$murl)=
			    &Apache::lonnet::decode_symb($symb);
                        if ($requrl eq '/adm/navmaps') {
                            &Apache::lonnet::symblist($map,$murl =>[$murl,$mid]);
                        } else {
                            if (($map =~ /\.page$/) && ($requrl !~ /\.page$/)) {
                                my $mapsymb = &Apache::lonnet::symbread($map);
                                ($map,$mid,$murl)=&Apache::lonnet::decode_symb($mapsymb);
                            }
			    &Apache::lonnet::symblist($map,$murl =>[$murl,$mid],
						      'last_known' =>[$murl,$mid]);
                        }
		    }
		}
		$env{'request.symb'}=$symb;
                if (($env{'request.symbread.cached.'}) && ($env{'request.symbread.cached.'} ne $symb)) {
                    $env{'request.symbread.cached.'} = $symb;
                }
		&Apache::lonnet::courseacclog($symb);
	    } else {
# ------------------------------------------------------- This is other content
		&Apache::lonnet::courseacclog($requrl);    
	    }
            if ($requrl =~ m{^/+uploaded/\Q$cdom\E/\Q$cnum\E/(docs|supplemental)/.+\.html?$}) {
                if (&Apache::lonnet::allowed('mdc',$env{'request.course.id'})) {
                    if ($query) {
                        &Apache::loncommon::get_unprocessed_cgi($query,['forceedit']);
                        if ($env{'form.forceedit'}) {
                            $env{'request.state'} = 'edit';
                        }
                    }
                }
            } elsif ($requrl =~ m{^/+uploaded/\Q$cdom\E/\Q$cnum\E/portfolio/syllabus/.+\.html?$}) {
                if (&Apache::lonnet::allowed('mdc',$env{'request.course.id'})) {
                    if ($query) {
                        &Apache::loncommon::get_unprocessed_cgi($query,['forceedit','editmode']);
                        if (($env{'form.forceedit'}) || ($env{'form.editmode'})) {
                            $env{'request.state'} = 'edit';
                        }
                    }
                }
            }
	}
	return OK;
    } else {
        my $defdom=$r->dir_config('lonDefDomain');
        ($is_balancer,$otherserver) =
            &Apache::lonnet::check_loadbalancing(undef,$defdom);
        if ($is_balancer) {
            $r->set_handlers('PerlResponseHandler'=>
                             [\&Apache::switchserver::handler]);
            if ($otherserver ne '') {
                $env{'form.otherserver'} = $otherserver;
            }
        }
    }
# -------------------------------------------- See if this is a public resource
    if ($requrl=~m|^/+adm/+help/+|) {
 	return OK;
    }
# ------------------------------------ See if this is a viewable portfolio file
    if (&Apache::lonnet::is_portfolio_url($requrl)) {
        my $clientip = &Apache::lonnet::get_requestor_ip($r);
        my $access=&Apache::lonnet::allowed('bre',$requrl,undef,undef,$clientip);
	if ($access eq 'A') {
	    &Apache::restrictedaccess::setup_handler($r);
	    return OK;
	}
	if (($access ne '2') && ($access ne 'F')) {
	    $env{'user.error.msg'}="$requrl:bre:1:1:Access Denied";
	    return HTTP_NOT_ACCEPTABLE;
	}
    }

# -------------------------------------------------------------- Not authorized
    $requrl=~/\.(\w+)$/;
#    if ((&Apache::loncommon::fileembstyle($1) eq 'ssi') ||
#        ($requrl=~/^\/adm\/(roles|logout|email|menu|remote)/) ||
#        ($requrl=~m|^/prtspool/|)) {
# -------------------------- Store where they wanted to go and get login screen
	$env{'request.querystring'}=$r->args;
	$env{'request.firsturl'}=$requrl;
       return FORBIDDEN;
#   } else {
# --------------------------------------------------------------------- Goodbye
#       return HTTP_BAD_REQUEST;
#   }
}

1;
__END__

=pod

=back

=cut