#!/usr/bin/perl

use strict;
use Getopt::Long;
use Pod::Usage;

=pod

=head1 NAME

 ext_sql_session_acl - SQL Database session lookup helper for Squid

=head1 SYNOPSIS

 ext_sql_session_acl [options]

=head1 DESCRIPTION

Validates an HTTP requests access authorization with a session database.

Taking an identity token to be validated (as determined by the external_acl_type format)
it returns a username or tag associated with the identity token passed in.

Common forms of identifiers are IP address, EUI (MAC) address, passwords, or UUID tokens.

This program uses Squid concurrency support.

=head1 OPTIONS

=over 12

=item B<--dsn>

Database DSN. Default "DBI:mysql:database=squid"

=item B<--user>

Database User

=item B<--password>

Database password

=item B<--table>

Database table. Default "passwd".

=item B<--uidcol>

Unique Session Identifier column. Default "id".

=item B<--usercol>

External ACL user= result column.

=item B<--tagcol>

External ACL tag= result column.

=item B<--cond>

Condition, defaults to enabled=1. Specify 1 or "" for no condition

=item B<--persist>

Keep a persistent database connection open between queries.

=item B<--debug>

Write debug info to stderr.

=back

=head1 AUTHOR

This program and documentation was written by I<Amos Jeffries <amosjeffries@squid-cache.org>>

Based on original work in DB_auth by Henrik Nordstrom <henrik@henriknordstrom.net>
With assistance of Nishant Sharma <codemarauder@gmail.com>

=head1 COPYRIGHT

 * Copyright (C) 1996-2023 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.

 Copyright (C) 2012 Amos Jeffries <amosjeffries@squid-cache.org>

 This program is free software. You may redistribute copies of it under the
 terms of the GNU General Public License version 2, or (at your opinion) any
 later version.

=head1 QUESTIONS

Questions on the usage of this program can be sent to the I<Squid Users mailing list <squid-users@lists.squid-cache.org>>

=head1 REPORTING BUGS

Bug reports need to be made in English.
See https://wiki.squid-cache.org/SquidFaq/BugReporting for details of what you need to include with your bug report.

Report bugs or bug fixes using https://bugs.squid-cache.org/

Report serious security bugs to I<Squid Bugs <squid-bugs@lists.squid-cache.org>>

Report ideas for new improvements to the I<Squid Developers mailing list <squid-dev@lists.squid-cache.org>>

=head1 SEE ALSO

squid (8), GPL (7),

The Squid FAQ wiki https://wiki.squid-cache.org/SquidFaq

The Squid Configuration Manual http://www.squid-cache.org/Doc/config/

=cut

use DBI;

my $dsn = "DBI:mysql:database=squid";
my $db_user = undef;
my $db_passwd = undef;
my $db_table = "passwd";
my $db_uidcol = "id";
my $db_usercol = "''";
my $db_tagcol = "''";
my $db_cond = "enabled = 1";
my $persist = 0;
my $debug = 0;

GetOptions(
    'dsn=s' => \$dsn,
    'user=s' => \$db_user,
    'password=s' => \$db_passwd,
    'table=s' => \$db_table,
    'uidcol=s' => \$db_uidcol,
    'usercol=s' => \$db_usercol,
    'tagcol=s' => \$db_tagcol,
    'cond=s' => \$db_cond,
    'persist' => \$persist,
    'debug' => \$debug,
    );

my ($_dbh, $_sth);

sub close_db()
{
    return if !defined($_dbh);
    undef $_sth;
    $_dbh->disconnect();
    undef $_dbh;
}

sub open_db()
{
    return $_sth if defined $_sth;
    $_dbh = DBI->connect($dsn, $db_user, $db_passwd);
    if (!defined $_dbh) {
        warn ("Could not connect to $dsn\n");
        return undef;
    }
    $_sth = $_dbh->prepare("SELECT $db_usercol as 'user', $db_tagcol as 'tag' FROM $db_table WHERE ($db_uidcol = ?) " .
            ($db_cond ne "" ? " AND $db_cond" : "")) || die;

    print(stderr "Query: SELECT $db_usercol as 'user', $db_tagcol as 'tag' FROM $db_table WHERE ($db_uidcol = ?) " .
            ($db_cond ne "" ? " AND $db_cond" : "")) if ($debug);

    return $_sth;
}

sub query_db($) {
    my $uid = @_[0];
    my ($sth) = open_db() || return undef;
    print(stderr "UID queried: '".$uid."'\n") if ($debug);
    if (!$sth->execute($uid)) {
        close_db();
        open_db() || return undef;
        $sth->execute($uid) || return undef;;
    }
    return $sth;
}
my $status;

$|=1;
while (<>) {
    my $string = $_;
    $string =~ m/^(\d+)\s(.*)$/;
    my ($cid, $uid) = ($1, $2);

    $status = "ERR";
    $cid =~ s/%(..)/pack("H*", $1)/ge;
    $uid =~ s/%(..)/pack("H*", $1)/ge;

    print(stderr "Received: Channel=".$cid.", UID='".$uid."'\n") if ($debug);

    $status = $cid . " BH message=\"database error\"";
    my $sth = query_db($uid) || next;
    print(stderr "Rows: ". $sth->rows()."\n") if ($debug);
    $status = $cid . " ERR message=\"unknown UID '".$uid."'\"";
    my $row = $sth->fetchrow_hashref() || next;
    $status = $cid . " OK" . ($row->{'user'} ne "" ? " user=" . $row->{'user'} : "" ) . ($row->{'tag'} ne "" ? " tag=" . $row->{'tag'} : "" );
    $sth->finish();
} continue {
    close_db() if (!$persist);
    print $status . "\n";
}
