And here's an untested version which should hopefully work.
<?php
/**
* PunBB auth backend
*
* Uses external Trust mechanism to check against PunBB's
* user cookie. PunBB's PUN_ROOT must be defined correctly.
*
* @author Andreas Gohr <andi@splitbrain.org>
*/
if(!defined('PUN_ROOT')) define('PUN_ROOT', DOKU_INC.'../forum/');
if(get_magic_quotes_gpc()){
nice_die('Sorry the punbb auth backend requires the PHP option
<a href="http://www.php.net/manual/en/ref.info.php#ini.magic-quotes-gpc">magic_quotes_gpc</a>
to be disabled for proper operation. Either setup your PHP install accordingly or
choose a different auth backend.');
}
require_once PUN_ROOT.'include/common.php';
require_once DOKU_INC.'inc/auth/mysql.class.php';
#dbg($GLOBALS);
#dbg($pun_user);
class auth_punbb extends auth_mysql {
/**
* Constructor.
*
* Sets additional capabilities and config strings
*/
function auth_punbb(){
global $conf;
$this->cando['external'] = true;
$this->cando['logoff'] = true;
// make sure we use a crypt understood by punbb
if(function_exists('sha1')){
$conf['passcrypt'] = 'sha1';
}else{
$conf['passcrypt'] = 'md5';
}
// get global vars from PunBB config
global $db_host;
global $db_name;
global $db_username;
global $db_password;
global $db_prefix;
// now set up the mysql config strings
$conf['auth']['mysql']['server'] = $db_host;
$conf['auth']['mysql']['user'] = $db_username;
$conf['auth']['mysql']['password'] = $db_password;
$conf['auth']['mysql']['database'] = $db_name;
$conf['auth']['mysql']['checkPass'] = "SELECT u.password AS pass
FROM ${db_prefix}users AS u, ${db_prefix}groups AS g
WHERE u.group_id = g.g_id
AND u.username = '%{user}'
AND g.g_title != 'Guest'";
$conf['auth']['mysql']['getUserInfo'] = "SELECT password AS pass, realname AS name, email AS mail,
id, g_title as `group`
FROM ${db_prefix}users AS u, ${db_prefix}groups AS g
WHERE u.group_id = g.g_id
AND u.username = '%{user}'";
$conf['auth']['mysql']['getGroups'] = "SELECT g.g_title as `group`
FROM ${db_prefix}users AS u, ${db_prefix}groups AS g
WHERE u.group_id = g.g_id
AND u.username = '%{user}'";
$conf['auth']['mysql']['getUsers'] = "SELECT DISTINCT u.username AS user
FROM ${db_prefix}users AS u, ${db_prefix}groups AS g
WHERE u.group_id = g.g_id";
$conf['auth']['mysql']['FilterLogin'] = "u.username LIKE '%{user}'";
$conf['auth']['mysql']['FilterName'] = "u.realname LIKE '%{name}'";
$conf['auth']['mysql']['FilterEmail'] = "u.email LIKE '%{email}'";
$conf['auth']['mysql']['FilterGroup'] = "g.g_title LIKE '%{group}'";
$conf['auth']['mysql']['SortOrder'] = "ORDER BY u.username";
$conf['auth']['mysql']['addUser'] = "INSERT INTO ${db_prefix}users
(username, password, email, realname)
VALUES ('%{user}', '%{pass}', '%{email}', '%{name}')";
$conf['auth']['mysql']['addGroup'] = "INSERT INTO ${db_prefix}groups (g_title) VALUES ('%{group}')";
$conf['auth']['mysql']['addUserGroup']= "UPDATE ${db_prefix}users
SET group_id=%{gid}
WHERE id='%{uid}'";
$conf['auth']['mysql']['delGroup'] = "DELETE FROM ${db_prefix}groups WHERE g_id='%{gid}'";
$conf['auth']['mysql']['getUserID'] = "SELECT id FROM ${db_prefix}users WHERE username='%{user}'";
$conf['auth']['mysql']['updateUser'] = "UPDATE ${db_prefix}users SET";
$conf['auth']['mysql']['UpdateLogin'] = "username='%{user}'";
$conf['auth']['mysql']['UpdatePass'] = "password='%{pass}'";
$conf['auth']['mysql']['UpdateEmail'] = "email='%{email}'";
$conf['auth']['mysql']['UpdateName'] = "realname='%{name}'";
$conf['auth']['mysql']['UpdateTarget']= "WHERE id=%{uid}";
$conf['auth']['mysql']['delUserGroup']= "UPDATE ${db_prefix}users SET g_id=4 WHERE id=%{uid}";
$conf['auth']['mysql']['getGroupID'] = "SELECT g_id AS id FROM ${db_prefix}groups WHERE g_title='%{group}'";
$conf['auth']['mysql']['TablesToLock']= array("${db_prefix}users", "${db_prefix}users AS u",
"${db_prefix}groups", "${db_prefix}groups AS g");
$conf['auth']['mysql']['debug'] = 1;
// call mysql constructor
$this->auth_mysql();
}
/**
* Just checks against the $pun_user variable
*/
function trustExternal($user,$pass,$sticky=false){
global $USERINFO;
global $conf;
global $lang;
global $pun_user;
global $pun_config;
global $cookie_name;
$sticky ? $sticky = true : $sticky = false; //sanity check
// someone used the login form
if(!empty($user)){
authenticate_user($user, $pass);
if (!$pun_user['is_guest']){
$expire = ($pun_user['save_pass'] == '1') ? time() + 31536000 : 0;
pun_setcookie($cookie_name, base64_encode($pun_user['id'].'|'.$pun_user['password']), $expire);
}else{
//invalid credentials - log off
msg($lang['badlogin'],-1);
auth_logoff();
return false;
}
}
if(isset($pun_user) && !$pun_user['is_guest']){
// okay we're logged in - set the globals
$USERINFO['pass'] = $pun_user['password'];
$USERINFO['name'] = $pun_user['realname'];
$USERINFO['mail'] = $pun_user['email'];
$USERINFO['grps'] = array($pun_user['g_title']);
$_SERVER['REMOTE_USER'] = $pun_user['username'];
$_SESSION[DOKU_COOKIE]['auth']['user'] = $pun_user['username'];
$_SESSION[DOKU_COOKIE]['auth']['info'] = $USERINFO;
return true;
}
// to be sure
auth_logoff();
return false;
}
/**
* remove punbb cookie on logout
*/
function logOff(){
global $pun_user;
global $cookie_name;
$pun_user = array();
$pun_user['is_guest'] = true;
pun_setcookie($cookie_name, base64_encode('1|'.random_key(8, true)), time() + 31536000);
}
}
//Setup VIM: ex: et ts=2 enc=utf-8 :
This code can probably be greatly shortened: I think I removed the dependency on the MySQL auth class, since the script includes common.php anyway, which means the PunBB database connection already exists/
Maybe there is the problem 
