Add LinkTokens service

[MAILPOET-2340]

lib/Subscribers/LinkTokens.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace MailPoet\Subscribers;
+
+use MailPoet\Models\Subscriber;
+
+class LinkTokens {
+  const OBSOLETE_LINK_TOKEN_LENGTH = 6;
+  const LINK_TOKEN_LENGTH = 32;
+
+  function getToken(Subscriber $subscriber) {
+    if ($subscriber->link_token === null) {
+      $subscriber->link_token = $this->generateToken($subscriber->email);
+      // `$subscriber->save()` fails if the subscriber has subscriptions, segments or custom fields
+      \ORM::rawExecute(sprintf('UPDATE %s SET link_token = ? WHERE email = ?', Subscriber::$_table), [$subscriber->link_token, $subscriber->email]);
+    }
+    return $subscriber->link_token;
+  }
+
+  function verifyToken(Subscriber $subscriber, $token) {
+    $database_token = $subscriber->getLinkToken();
+    $request_token = substr($token, 0, strlen($database_token));
+    return call_user_func(
+      'hash_equals',
+      $database_token,
+      $request_token
+    );
+  }
+
+  /**
+   * Only for backward compatibility for old tokens
+   */
+  private function generateToken($email = null, $length = self::OBSOLETE_LINK_TOKEN_LENGTH) {
+    if ($email !== null) {
+      $auth_key = '';
+      if (defined('AUTH_KEY')) {
+        $auth_key = AUTH_KEY;
+      }
+      return substr(md5($auth_key . $email), 0, $length);
+    }
+    return false;
+  }
+
+}