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<?php
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/**
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* @file
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* Pubsubhubbub subscriber library.
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*
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* Readme
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* http://github.com/lxbarth/PuSHSubscriber
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*
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* License
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* http://github.com/lxbarth/PuSHSubscriber/blob/master/LICENSE.txt
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*/
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/**
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* PubSubHubbub subscriber.
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*/
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class PuSHSubscriber {
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protected $domain;
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protected $subscriber_id;
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protected $subscription_class;
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protected $env;
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/**
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* Singleton.
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*
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* PuSHSubscriber identifies a unique subscription by a domain and a numeric
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* id. The numeric id is assumed to e unique in its domain.
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*
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* @param $domain
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* A string that identifies the domain in which $subscriber_id is unique.
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* @param $subscriber_id
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* A numeric subscriber id.
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* @param $subscription_class
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* The class to use for handling subscriptions. Class MUST implement
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* PuSHSubscriberSubscriptionInterface
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* @param PuSHSubscriberEnvironmentInterface $env
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* Environmental object for messaging and logging.
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*/
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public static function instance($domain, $subscriber_id, $subscription_class, PuSHSubscriberEnvironmentInterface $env) {
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static $subscribers;
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if (!isset($subscriber[$domain][$subscriber_id])) {
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$subscriber = new PuSHSubscriber($domain, $subscriber_id, $subscription_class, $env);
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}
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return $subscriber;
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}
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/**
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* Protect constructor.
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*/
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protected function __construct($domain, $subscriber_id, $subscription_class, PuSHSubscriberEnvironmentInterface $env) {
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$this->domain = $domain;
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$this->subscriber_id = $subscriber_id;
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$this->subscription_class = $subscription_class;
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$this->env = $env;
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}
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/**
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* Subscribe to a given URL. Attempt to retrieve 'hub' and 'self' links from
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* document at $url and issue a subscription request to the hub.
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*
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* @param $url
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* The URL of the feed to subscribe to.
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* @param $callback_url
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* The full URL that hub should invoke for subscription verification or for
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* notifications.
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* @param $hub
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* The URL of a hub. If given overrides the hub URL found in the document
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* at $url.
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*/
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public function subscribe($url, $callback_url, $hub = '') {
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// Fetch document, find rel=hub and rel=self.
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// If present, issue subscription request.
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$request = curl_init($url);
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curl_setopt($request, CURLOPT_FOLLOWLOCATION, TRUE);
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curl_setopt($request, CURLOPT_RETURNTRANSFER, TRUE);
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$data = curl_exec($request);
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if (curl_getinfo($request, CURLINFO_HTTP_CODE) == 200) {
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try {
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$xml = @ new SimpleXMLElement($data);
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$xml->registerXPathNamespace('atom', 'http://www.w3.org/2005/Atom');
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if (empty($hub) && $hub = @current($xml->xpath("//atom:link[attribute::rel='hub']"))) {
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$hub = (string) $hub->attributes()->href;
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}
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if ($self = @current($xml->xpath("//atom:link[attribute::rel='self']"))) {
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$self = (string) $self->attributes()->href;
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}
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}
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catch (Exception $e) {
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// Do nothing.
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}
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}
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curl_close($request);
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// Fall back to $url if $self is not given.
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if (!$self) {
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$self = $url;
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}
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if (!empty($hub) && !empty($self)) {
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$this->request($hub, $self, 'subscribe', $callback_url);
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}
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}
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/**
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* @todo Unsubscribe from a hub.
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* @todo Make sure we unsubscribe with the correct topic URL as it can differ
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* from the initial subscription URL.
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*
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* @param $topic_url
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* The URL of the topic to unsubscribe from.
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* @param $callback_url
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* The callback to unsubscribe.
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*/
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public function unsubscribe($topic_url, $callback_url) {
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if ($sub = $this->subscription()) {
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$this->request($sub->hub, $sub->topic, 'unsubscribe', $callback_url);
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$sub->delete();
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}
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}
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/**
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* Request handler for subscription callbacks.
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*/
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public function handleRequest($callback) {
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if (isset($_GET['hub_challenge'])) {
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$this->verifyRequest();
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}
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// No subscription notification has ben sent, we are being notified.
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else {
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if ($raw = $this->receive()) {
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$callback($raw, $this->domain, $this->subscriber_id);
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}
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}
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}
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/**
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* Receive a notification.
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*
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* @param $ignore_signature
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* If FALSE, only accept payload if there is a signature present and the
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* signature matches the payload. Warning: setting to TRUE results in
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* unsafe behavior.
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*
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* @return
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* An XML string that is the payload of the notification if valid, FALSE
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* otherwise.
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*/
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public function receive($ignore_signature = FALSE) {
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/**
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* Verification steps:
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*
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* 1) Verify that this is indeed a POST reuest.
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* 2) Verify that posted string is XML.
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* 3) Per default verify sender of message by checking the message's
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* signature against the shared secret.
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*/
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if ($_SERVER['REQUEST_METHOD'] == 'POST') {
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$raw = file_get_contents('php://input');
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if (@simplexml_load_string($raw)) {
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if ($ignore_signature) {
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return $raw;
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}
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if (isset($_SERVER['HTTP_X_HUB_SIGNATURE']) && ($sub = $this->subscription())) {
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$result = array();
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parse_str($_SERVER['HTTP_X_HUB_SIGNATURE'], $result);
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if (isset($result['sha1']) && $result['sha1'] === hash_hmac('sha1', $raw, $sub->secret)) {
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return $raw;
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}
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else {
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$this->log('Could not verify signature.', 'error');
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}
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}
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else {
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$this->log('No signature present.', 'error');
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}
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}
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}
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return FALSE;
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}
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/**
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* Verify a request. After a hub has received a subscribe or unsubscribe
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* request (see PuSHSubscriber::request()) it sends back a challenge verifying
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* that an action indeed was requested ($_GET['hub_challenge']). This
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* method handles the challenge.
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*/
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public function verifyRequest() {
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if (!isset($_GET['hub_challenge'])) {
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return $this->rejectRequest();
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}
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// Don't accept modes of 'subscribed' or 'unsubscribed'.
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if ($_GET['hub_mode'] !== 'subscribe' && $_GET['hub_mode'] !== 'unsubscribe') {
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return $this->rejectRequest();
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}
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// No available subscription.
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if (!$sub = $this->subscription()) {
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return $this->rejectRequest();
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}
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// Not what we asked for.
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if ($_GET['hub_mode'] !== $sub->status) {
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return $this->rejectRequest();
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}
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// Wrong URL.
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if ($_GET['hub_topic'] !== $sub->topic) {
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return $this->rejectRequest();
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}
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if ($sub->status === 'subscribe') {
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$sub->status = 'subscribed';
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$this->log('Verified "subscribe" request.');
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}
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else {
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$sub->status = 'unsubscribed';
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$this->log('Verified "unsubscribe" request.');
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}
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$sub->post_fields = array();
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$sub->save();
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header('HTTP/1.1 200 "Found"', NULL, 200);
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print check_plain($_GET['hub_challenge']);
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drupal_exit();
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}
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/**
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* Issue a subscribe or unsubcribe request to a PubsubHubbub hub.
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*
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* @param $hub
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* The URL of the hub's subscription endpoint.
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* @param $topic
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* The topic URL of the feed to subscribe to.
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* @param $mode
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* 'subscribe' or 'unsubscribe'.
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* @param $callback_url
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* The subscriber's notifications callback URL.
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*
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* Compare to http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.2.html#anchor5
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*
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* @todo Make concurrency safe.
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*/
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protected function request($hub, $topic, $mode, $callback_url) {
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$secret = drupal_random_key(40);
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$post_fields = array(
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'hub.callback' => $callback_url,
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'hub.mode' => $mode,
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'hub.topic' => $topic,
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'hub.verify' => 'sync',
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'hub.lease_seconds' => '', // Permanent subscription.
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'hub.secret' => $secret,
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);
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$sub = new $this->subscription_class($this->domain, $this->subscriber_id, $hub, $topic, $secret, $mode, $post_fields);
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$sub->save();
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// Issue subscription request.
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$request = curl_init($hub);
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curl_setopt($request, CURLOPT_POST, TRUE);
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curl_setopt($request, CURLOPT_POSTFIELDS, $post_fields);
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curl_setopt($request, CURLOPT_RETURNTRANSFER, TRUE);
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curl_exec($request);
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$code = curl_getinfo($request, CURLINFO_HTTP_CODE);
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if (in_array($code, array(202, 204))) {
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$this->log("Positive response to \"$mode\" request ($code).");
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}
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else {
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$sub->status = $mode . ' failed';
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$sub->save();
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$this->log("Error issuing \"$mode\" request to $hub ($code).", 'error');
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}
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curl_close($request);
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}
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/**
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* Get the subscription associated with this subscriber.
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*
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* @return
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* A PuSHSubscriptionInterface object if a subscription exist, NULL
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* otherwise.
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*/
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public function subscription() {
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return call_user_func(array($this->subscription_class, 'load'), $this->domain, $this->subscriber_id);
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}
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/**
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* Determine whether this subscriber is successfully subscribed or not.
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*/
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public function subscribed() {
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if ($sub = $this->subscription()) {
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if ($sub->status == 'subscribed') {
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return TRUE;
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}
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}
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return FALSE;
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}
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/**
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* Helper for messaging.
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*/
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protected function msg($msg, $level = 'status') {
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$this->env->msg($msg, $level);
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}
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/**
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* Helper for logging.
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*/
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protected function log($msg, $level = 'status') {
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$this->env->log("{$this->domain}:{$this->subscriber_id}\t$msg", $level);
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}
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/**
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* Rejects a request subscription request.
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*/
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protected function rejectRequest() {
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header('HTTP/1.1 404 "Not Found"', NULL, 404);
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$this->log('Could not verify subscription.', 'error');
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drupal_exit();
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}
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}
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/**
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* Implement to provide a storage backend for subscriptions.
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323
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*
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324
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* Variables passed in to the constructor must be accessible as public class
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325
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* variables.
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*/
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327
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interface PuSHSubscriptionInterface {
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328
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/**
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* @param $domain
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330
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* A string that defines the domain in which the subscriber_id is unique.
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331
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* @param $subscriber_id
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332
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* A unique numeric subscriber id.
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* @param $hub
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* The URL of the hub endpoint.
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335
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* @param $topic
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336
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* The topic to subscribe to.
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337
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* @param $secret
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338
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* A secret key used for message authentication.
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339
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* @param $status
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340
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* The status of the subscription.
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341
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* 'subscribe' - subscribing to a feed.
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342
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* 'unsubscribe' - unsubscribing from a feed.
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* 'subscribed' - subscribed.
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* 'unsubscribed' - unsubscribed.
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345
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* 'subscribe failed' - subscribe request failed.
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346
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* 'unsubscribe failed' - unsubscribe request failed.
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347
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* @param $post_fields
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348
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* An array of the fields posted to the hub.
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349
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*/
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350
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public function __construct($domain, $subscriber_id, $hub, $topic, $secret, $status = '', $post_fields = '');
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351
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352
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/**
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353
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* Save a subscription.
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354
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*/
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355
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public function save();
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356
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357
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/**
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358
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* Load a subscription.
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359
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*
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360
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* @return
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361
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* A PuSHSubscriptionInterface object if a subscription exist, NULL
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362
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* otherwise.
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363
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*/
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364
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public static function load($domain, $subscriber_id);
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365
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366
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/**
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367
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* Delete a subscription.
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368
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*/
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369
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public function delete();
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370
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}
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371
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372
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/**
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373
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* Implement to provide environmental functionality like user messages and
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374
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* logging.
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375
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*/
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376
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interface PuSHSubscriberEnvironmentInterface {
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377
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/**
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378
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* A message to be displayed to the user on the current page load.
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379
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*
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380
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* @param $msg
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381
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* A string that is the message to be displayed.
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382
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* @param $level
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383
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* A string that is either 'status', 'warning' or 'error'.
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384
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*/
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385
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public function msg($msg, $level = 'status');
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386
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387
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/**
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388
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* A log message to be logged to the database or the file system.
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389
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*
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390
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* @param $msg
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391
|
* A string that is the message to be displayed.
|
|
392
|
* @param $level
|
|
393
|
* A string that is either 'status', 'warning' or 'error'.
|
|
394
|
*/
|
|
395
|
public function log($msg, $level = 'status');
|
|
396
|
}
|
