moodle/rss/file.php

<?PHP
    //This file returns the required rss feeds
    //The URL format MUST include:
    //    context: the context id
    //    user:   the user id
    //    name:   the name of the module (forum...)
    //    id:     the id (instance) of the module (forumid...)
    //If the course has a password or it doesn't
    //allow guest access then the user field is
    //required to see that the user is enrolled
    //in the course, else no check is performed.
    //This allows to limit a bit the rss access
    //to correct users. It isn't unbreakable,
    //obviously, but its the best I've thought!!

// disable moodle specific debug messages and any errors in output
define('NO_DEBUG_DISPLAY', true);//comment this out to see any error messages during RSS generation

// session not used here
define('NO_MOODLE_COOKIES', true);

require_once('../config.php');
require_once($CFG->libdir.'/filelib.php');
require_once($CFG->libdir.'/rsslib.php');

//Check RSS feeds are enabled
if (empty($CFG->enablerssfeeds)) {
    debugging('DISABLED (admin variables)');
    rss_not_found();
}

$lifetime = 3600;  // Seconds for files to remain in caches - 1 hour
$filename   = 'rss.xml';

// this is a big one big hack - NO_MOODLE_COOKIES is not compatible with capabilities MDL-7243
// it should be replaced once we get to codes in urls

$relativepath = get_file_argument();
if (!$relativepath) {
    rss_not_found();
}

// extract relative path components
$args = explode('/', trim($relativepath, '/'));
if (count($args) < 5) {
    rss_not_found();
}

$contextid   = (int)$args[0];
$token  = $args[1];
$modulename = clean_param($args[2], PARAM_FILE);
$instance   = $args[3];

$userid = rss_get_userid_from_token($token);
if (!$userid) {
    rss_not_authenticated();
}
$user = get_complete_user_data('id', $userid);
session_set_user($user);

//Set context
$context = get_context_instance_by_id($contextid);
if (!$context) {
    rss_not_found();
}
$PAGE->set_context($context);

//Get course from context
//TODO: note that in the case of the hub rss feed, the feed is not related to a course context,
//it is more a "site" context. The Hub RSS bypass the following line using context id = 2
$coursecontext = get_course_context($context);
$course = $DB->get_record('course', array('id' => $coursecontext->instanceid), '*', MUST_EXIST);

$pathname = null;

switch ($modulename) {
    case 'blog':
        $blogid = (int) $args[4];  // could be groupid / courseid  / userid  depending on $instance
        if ($args[5] != 'rss.xml') {
            $tagid = (int) $args[5];
        } else {
            $tagid = 0;
        }

        try {
            require_login($course, false, NULL, false, true);
        } catch (Exception $e) {
            rss_not_found();
        }

        //Work out the filename of the cached RSS file
        require_once($CFG->dirroot . '/blog/rsslib.php');
        $pathname = blog_generate_rss_feed($instance, $blogid, $tagid);
        break;

    case 'local_hub': //Note: I made this case generic for a probable futur refactor.
        // rss/file.php should not handle individual cases.
        //Here $modulename contain the folder path with '_' instead of '/'
        
        //Work out the filename of the cached RSS file
        $functionname = $modulename . '_rss_get_feed';
        $modulepath = str_replace('_', '/', $modulename);
        require_once($CFG->dirroot . '/' . $modulepath . '/rsslib.php');
        if (function_exists($functionname)) {
            $pathname = $functionname($args); //All the xxx_rss_get_feed() could manage
            // eveything with only $args parameter.
        }
        break;

    default:
        $instance = (int) $instance;

        $mods = get_plugin_list('mod');
        $mods = array_keys($mods);
        if (!in_array(strtolower($modulename), $mods)) {
            rss_not_found();
        }
        try {
            $cm = get_coursemodule_from_instance($modulename, $instance, 0, false, MUST_EXIST);
            require_login($course, false, $cm, false, true);
        } catch (Exception $e) {
            rss_not_found();
        }

        //Work out the filename of the cached RSS file
        $functionname = $cm->modname . '_rss_get_feed';
        require_once($CFG->dirroot . "/mod/{$cm->modname}/rsslib.php");
        if (function_exists($functionname)) {
            $pathname = $functionname($context, $cm, $instance, $args);
        }
        break;
}

//Check that file exists
if (empty($pathname) || !file_exists($pathname)) {
    rss_not_found();
}

//rss_update_token_last_access($USER->id);

//Send it to user!
send_file($pathname, $filename, $lifetime);

function rss_not_found() {
    /// error, send some XML with error message
    global $lifetime, $filename;
    send_file(rss_geterrorxmlfile(), $filename, $lifetime, false, true);
}

function rss_not_authenticated() {
    global $lifetime, $filename;
    send_file(rss_geterrorxmlfile('rsserrorauth'), $filename, $lifetime, false, true);
}