Improve documentation on password reset by dividing it into steps

Previously, PHP's configuration directives 'session.cookie_httponly'
and 'session.cookie_secure' were always overwritten with duplicated
and separately tracked variants of each directive

Database/MySQL.sql

@@ -1,9 +1,21 @@
+-- PHP-Auth (https://github.com/delight-im/PHP-Auth)
+-- Copyright (c) delight.im (https://www.delight.im/)
+-- Licensed under the MIT License (https://opensource.org/licenses/MIT)
+
+/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
+/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
+/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
+/*!40101 SET NAMES utf8mb4 */;
+
 CREATE TABLE IF NOT EXISTS `users` (
   `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
   `email` varchar(249) COLLATE utf8mb4_unicode_ci NOT NULL,
   `password` varchar(255) CHARACTER SET latin1 COLLATE latin1_general_cs NOT NULL,
   `username` varchar(100) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
+  `status` tinyint(2) unsigned NOT NULL DEFAULT '0',
   `verified` tinyint(1) unsigned NOT NULL DEFAULT '0',
+  `resettable` tinyint(1) unsigned NOT NULL DEFAULT '1',
+  `roles_mask` int(10) unsigned NOT NULL DEFAULT '0',
   `registered` int(10) unsigned NOT NULL,
   `last_login` int(10) unsigned DEFAULT NULL,
   PRIMARY KEY (`id`),
@@ -12,13 +24,15 @@ CREATE TABLE IF NOT EXISTS `users` (
 
 CREATE TABLE IF NOT EXISTS `users_confirmations` (
   `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
+  `user_id` int(10) unsigned NOT NULL,
   `email` varchar(249) COLLATE utf8mb4_unicode_ci NOT NULL,
   `selector` varchar(16) CHARACTER SET latin1 COLLATE latin1_general_cs NOT NULL,
   `token` varchar(255) CHARACTER SET latin1 COLLATE latin1_general_cs NOT NULL,
   `expires` int(10) unsigned NOT NULL,
   PRIMARY KEY (`id`),
   UNIQUE KEY `selector` (`selector`),
-  KEY `email_expires` (`email`,`expires`)
+  KEY `email_expires` (`email`,`expires`),
+  KEY `user_id` (`user_id`)
 ) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
 CREATE TABLE IF NOT EXISTS `users_remembered` (
@@ -35,20 +49,23 @@ CREATE TABLE IF NOT EXISTS `users_remembered` (
 CREATE TABLE IF NOT EXISTS `users_resets` (
   `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
   `user` int(10) unsigned NOT NULL,
-  `selector` varchar(24) CHARACTER SET latin1 COLLATE latin1_general_cs NOT NULL,
+  `selector` varchar(20) CHARACTER SET latin1 COLLATE latin1_general_cs NOT NULL,
   `token` varchar(255) CHARACTER SET latin1 COLLATE latin1_general_cs NOT NULL,
   `expires` int(10) unsigned NOT NULL,
   PRIMARY KEY (`id`),
   UNIQUE KEY `selector` (`selector`),
-  KEY `user` (`user`)
+  KEY `user_expires` (`user`,`expires`)
 ) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
 CREATE TABLE IF NOT EXISTS `users_throttling` (
-  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
-  `action_type` enum('login','register','confirm_email') COLLATE utf8mb4_unicode_ci NOT NULL,
-  `selector` varchar(44) CHARACTER SET latin1 COLLATE latin1_general_cs DEFAULT NULL,
-  `time_bucket` int(10) unsigned NOT NULL,
-  `attempts` mediumint(8) unsigned NOT NULL DEFAULT '1',
-  PRIMARY KEY (`id`),
-  UNIQUE KEY `action_type_selector_time_bucket` (`action_type`,`selector`,`time_bucket`)
+  `bucket` varchar(44) CHARACTER SET latin1 COLLATE latin1_general_cs NOT NULL,
+  `tokens` float unsigned NOT NULL,
+  `replenished_at` int(10) unsigned NOT NULL,
+  `expires_at` int(10) unsigned NOT NULL,
+  PRIMARY KEY (`bucket`),
+  KEY `expires_at` (`expires_at`)
 ) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
+/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
+/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
+/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;

Database/SQLite.sql

@@ -0,0 +1,59 @@
+-- PHP-Auth (https://github.com/delight-im/PHP-Auth)
+-- Copyright (c) delight.im (https://www.delight.im/)
+-- Licensed under the MIT License (https://opensource.org/licenses/MIT)
+
+PRAGMA foreign_keys = OFF;
+
+CREATE TABLE "users" (
+	"id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL CHECK ("id" >= 0),
+	"email" VARCHAR(249) NOT NULL,
+	"password" VARCHAR(255) NOT NULL,
+	"username" VARCHAR(100) DEFAULT NULL,
+	"status" INTEGER NOT NULL CHECK ("status" >= 0) DEFAULT "0",
+	"verified" INTEGER NOT NULL CHECK ("verified" >= 0) DEFAULT "0",
+	"resettable" INTEGER NOT NULL CHECK ("resettable" >= 0) DEFAULT "1",
+	"roles_mask" INTEGER NOT NULL CHECK ("roles_mask" >= 0) DEFAULT "0",
+	"registered" INTEGER NOT NULL CHECK ("registered" >= 0),
+	"last_login" INTEGER CHECK ("last_login" >= 0) DEFAULT NULL,
+	CONSTRAINT "email" UNIQUE ("email")
+);
+
+CREATE TABLE "users_confirmations" (
+	"id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL CHECK ("id" >= 0),
+	"user_id" INTEGER NOT NULL CHECK ("user_id" >= 0),
+	"email" VARCHAR(249) NOT NULL,
+	"selector" VARCHAR(16) NOT NULL,
+	"token" VARCHAR(255) NOT NULL,
+	"expires" INTEGER NOT NULL CHECK ("expires" >= 0),
+	CONSTRAINT "selector" UNIQUE ("selector")
+);
+CREATE INDEX "users_confirmations.email_expires" ON "users_confirmations" ("email", "expires");
+CREATE INDEX "users_confirmations.user_id" ON "users_confirmations" ("user_id");
+
+CREATE TABLE "users_remembered" (
+	"id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL CHECK ("id" >= 0),
+	"user" INTEGER NOT NULL CHECK ("user" >= 0),
+	"selector" VARCHAR(24) NOT NULL,
+	"token" VARCHAR(255) NOT NULL,
+	"expires" INTEGER NOT NULL CHECK ("expires" >= 0),
+	CONSTRAINT "selector" UNIQUE ("selector")
+);
+CREATE INDEX "users_remembered.user" ON "users_remembered" ("user");
+
+CREATE TABLE "users_resets" (
+	"id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL CHECK ("id" >= 0),
+	"user" INTEGER NOT NULL CHECK ("user" >= 0),
+	"selector" VARCHAR(20) NOT NULL,
+	"token" VARCHAR(255) NOT NULL,
+	"expires" INTEGER NOT NULL CHECK ("expires" >= 0),
+	CONSTRAINT "selector" UNIQUE ("selector")
+);
+CREATE INDEX "users_resets.user_expires" ON "users_resets" ("user", "expires");
+
+CREATE TABLE "users_throttling" (
+	"bucket" VARCHAR(44) PRIMARY KEY NOT NULL,
+	"tokens" REAL NOT NULL CHECK ("tokens" >= 0),
+	"replenished_at" INTEGER NOT NULL CHECK ("replenished_at" >= 0),
+	"expires_at" INTEGER NOT NULL CHECK ("expires_at" >= 0)
+);
+CREATE INDEX "users_throttling.expires_at" ON "users_throttling" ("expires_at");

LICENSE

@@ -1,201 +1,21 @@
-                                 Apache License
-                           Version 2.0, January 2004
-                        http://www.apache.org/licenses/
+The MIT License (MIT)
 
-   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+Copyright (c) delight.im (https://www.delight.im/)
 
-   1. Definitions.
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
 
-      "License" shall mean the terms and conditions for use, reproduction,
-      and distribution as defined by Sections 1 through 9 of this document.
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
 
-      "Licensor" shall mean the copyright owner or entity authorized by
-      the copyright owner that is granting the License.
-
-      "Legal Entity" shall mean the union of the acting entity and all
-      other entities that control, are controlled by, or are under common
-      control with that entity. For the purposes of this definition,
-      "control" means (i) the power, direct or indirect, to cause the
-      direction or management of such entity, whether by contract or
-      otherwise, or (ii) ownership of fifty percent (50%) or more of the
-      outstanding shares, or (iii) beneficial ownership of such entity.
-
-      "You" (or "Your") shall mean an individual or Legal Entity
-      exercising permissions granted by this License.
-
-      "Source" form shall mean the preferred form for making modifications,
-      including but not limited to software source code, documentation
-      source, and configuration files.
-
-      "Object" form shall mean any form resulting from mechanical
-      transformation or translation of a Source form, including but
-      not limited to compiled object code, generated documentation,
-      and conversions to other media types.
-
-      "Work" shall mean the work of authorship, whether in Source or
-      Object form, made available under the License, as indicated by a
-      copyright notice that is included in or attached to the work
-      (an example is provided in the Appendix below).
-
-      "Derivative Works" shall mean any work, whether in Source or Object
-      form, that is based on (or derived from) the Work and for which the
-      editorial revisions, annotations, elaborations, or other modifications
-      represent, as a whole, an original work of authorship. For the purposes
-      of this License, Derivative Works shall not include works that remain
-      separable from, or merely link (or bind by name) to the interfaces of,
-      the Work and Derivative Works thereof.
-
-      "Contribution" shall mean any work of authorship, including
-      the original version of the Work and any modifications or additions
-      to that Work or Derivative Works thereof, that is intentionally
-      submitted to Licensor for inclusion in the Work by the copyright owner
-      or by an individual or Legal Entity authorized to submit on behalf of
-      the copyright owner. For the purposes of this definition, "submitted"
-      means any form of electronic, verbal, or written communication sent
-      to the Licensor or its representatives, including but not limited to
-      communication on electronic mailing lists, source code control systems,
-      and issue tracking systems that are managed by, or on behalf of, the
-      Licensor for the purpose of discussing and improving the Work, but
-      excluding communication that is conspicuously marked or otherwise
-      designated in writing by the copyright owner as "Not a Contribution."
-
-      "Contributor" shall mean Licensor and any individual or Legal Entity
-      on behalf of whom a Contribution has been received by Licensor and
-      subsequently incorporated within the Work.
-
-   2. Grant of Copyright License. Subject to the terms and conditions of
-      this License, each Contributor hereby grants to You a perpetual,
-      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
-      copyright license to reproduce, prepare Derivative Works of,
-      publicly display, publicly perform, sublicense, and distribute the
-      Work and such Derivative Works in Source or Object form.
-
-   3. Grant of Patent License. Subject to the terms and conditions of
-      this License, each Contributor hereby grants to You a perpetual,
-      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
-      (except as stated in this section) patent license to make, have made,
-      use, offer to sell, sell, import, and otherwise transfer the Work,
-      where such license applies only to those patent claims licensable
-      by such Contributor that are necessarily infringed by their
-      Contribution(s) alone or by combination of their Contribution(s)
-      with the Work to which such Contribution(s) was submitted. If You
-      institute patent litigation against any entity (including a
-      cross-claim or counterclaim in a lawsuit) alleging that the Work
-      or a Contribution incorporated within the Work constitutes direct
-      or contributory patent infringement, then any patent licenses
-      granted to You under this License for that Work shall terminate
-      as of the date such litigation is filed.
-
-   4. Redistribution. You may reproduce and distribute copies of the
-      Work or Derivative Works thereof in any medium, with or without
-      modifications, and in Source or Object form, provided that You
-      meet the following conditions:
-
-      (a) You must give any other recipients of the Work or
-          Derivative Works a copy of this License; and
-
-      (b) You must cause any modified files to carry prominent notices
-          stating that You changed the files; and
-
-      (c) You must retain, in the Source form of any Derivative Works
-          that You distribute, all copyright, patent, trademark, and
-          attribution notices from the Source form of the Work,
-          excluding those notices that do not pertain to any part of
-          the Derivative Works; and
-
-      (d) If the Work includes a "NOTICE" text file as part of its
-          distribution, then any Derivative Works that You distribute must
-          include a readable copy of the attribution notices contained
-          within such NOTICE file, excluding those notices that do not
-          pertain to any part of the Derivative Works, in at least one
-          of the following places: within a NOTICE text file distributed
-          as part of the Derivative Works; within the Source form or
-          documentation, if provided along with the Derivative Works; or,
-          within a display generated by the Derivative Works, if and
-          wherever such third-party notices normally appear. The contents
-          of the NOTICE file are for informational purposes only and
-          do not modify the License. You may add Your own attribution
-          notices within Derivative Works that You distribute, alongside
-          or as an addendum to the NOTICE text from the Work, provided
-          that such additional attribution notices cannot be construed
-          as modifying the License.
-
-      You may add Your own copyright statement to Your modifications and
-      may provide additional or different license terms and conditions
-      for use, reproduction, or distribution of Your modifications, or
-      for any such Derivative Works as a whole, provided Your use,
-      reproduction, and distribution of the Work otherwise complies with
-      the conditions stated in this License.
-
-   5. Submission of Contributions. Unless You explicitly state otherwise,
-      any Contribution intentionally submitted for inclusion in the Work
-      by You to the Licensor shall be under the terms and conditions of
-      this License, without any additional terms or conditions.
-      Notwithstanding the above, nothing herein shall supersede or modify
-      the terms of any separate license agreement you may have executed
-      with Licensor regarding such Contributions.
-
-   6. Trademarks. This License does not grant permission to use the trade
-      names, trademarks, service marks, or product names of the Licensor,
-      except as required for reasonable and customary use in describing the
-      origin of the Work and reproducing the content of the NOTICE file.
-
-   7. Disclaimer of Warranty. Unless required by applicable law or
-      agreed to in writing, Licensor provides the Work (and each
-      Contributor provides its Contributions) on an "AS IS" BASIS,
-      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
-      implied, including, without limitation, any warranties or conditions
-      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
-      PARTICULAR PURPOSE. You are solely responsible for determining the
-      appropriateness of using or redistributing the Work and assume any
-      risks associated with Your exercise of permissions under this License.
-
-   8. Limitation of Liability. In no event and under no legal theory,
-      whether in tort (including negligence), contract, or otherwise,
-      unless required by applicable law (such as deliberate and grossly
-      negligent acts) or agreed to in writing, shall any Contributor be
-      liable to You for damages, including any direct, indirect, special,
-      incidental, or consequential damages of any character arising as a
-      result of this License or out of the use or inability to use the
-      Work (including but not limited to damages for loss of goodwill,
-      work stoppage, computer failure or malfunction, or any and all
-      other commercial damages or losses), even if such Contributor
-      has been advised of the possibility of such damages.
-
-   9. Accepting Warranty or Additional Liability. While redistributing
-      the Work or Derivative Works thereof, You may choose to offer,
-      and charge a fee for, acceptance of support, warranty, indemnity,
-      or other liability obligations and/or rights consistent with this
-      License. However, in accepting such obligations, You may act only
-      on Your own behalf and on Your sole responsibility, not on behalf
-      of any other Contributor, and only if You agree to indemnify,
-      defend, and hold each Contributor harmless for any liability
-      incurred by, or claims asserted against, such Contributor by reason
-      of your accepting any such warranty or additional liability.
-
-   END OF TERMS AND CONDITIONS
-
-   APPENDIX: How to apply the Apache License to your work.
-
-      To apply the Apache License to your work, attach the following
-      boilerplate notice, with the fields enclosed by brackets "{}"
-      replaced with your own identifying information. (Don't include
-      the brackets!)  The text should be enclosed in the appropriate
-      comment syntax for the file format. We also recommend that a
-      file or class name and description of purpose be included on the
-      same "printed page" as the copyright notice for easier
-      identification within third-party archives.
-
-   Copyright {yyyy} {name of copyright owner}
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

Migration.md

@@ -1,35 +1,190 @@
 # Migration
 
- * `v1.x.x` to `v2.x.x`
-   * The MySQL schema has been changed from charset `utf8` to charset `utf8mb4` and from collation `utf8_general_ci` to collation `utf8mb4_unicode_ci`. Use the statements below to update the database schema:
+ * [General](#general)
+ * [From `v6.x.x` to `v7.x.x`](#from-v6xx-to-v7xx)
+ * [From `v5.x.x` to `v6.x.x`](#from-v5xx-to-v6xx)
+ * [From `v4.x.x` to `v5.x.x`](#from-v4xx-to-v5xx)
+ * [From `v3.x.x` to `v4.x.x`](#from-v3xx-to-v4xx)
+ * [From `v2.x.x` to `v3.x.x`](#from-v2xx-to-v3xx)
+ * [From `v1.x.x` to `v2.x.x`](#from-v1xx-to-v2xx)
+
+## General
+
+Update your version of this library using Composer and its `composer update` or `composer require` commands [[?]](https://github.com/delight-im/Knowledge/blob/master/Composer%20(PHP).md#how-do-i-update-libraries-or-modules-within-my-application).
+
+## From `v6.x.x` to `v7.x.x`
+
+ * The method `logOutButKeepSession` from class `Auth` is now simply called `logOut`. Therefore, the former method `logout` is now called `logOutAndDestroySession`.
+
+ * The second argument of the `Auth` constructor, which was named `$useHttps`, has been removed. If you previously had it set to `true`, make sure to set the value of the `session.cookie_secure` directive to `1` now. You may do so either directly in your [PHP configuration](http://php.net/manual/en/configuration.file.php) (`php.ini`), via the `\ini_set` method or via the `\session_set_cookie_params` method. Otherwise, make sure that directive is set to `0`.
+
+ * The third argument of the `Auth` constructor, which was named `$allowCookiesScriptAccess`, has been removed. If you previously had it set to `true`, make sure to set the value of the `session.cookie_httponly` directive to `0` now. You may do so either directly in your [PHP configuration](http://php.net/manual/en/configuration.file.php) (`php.ini`), via the `\ini_set` method or via the `\session_set_cookie_params` method. Otherwise, make sure that directive is set to `1`.
+
+ * Only if *both* of the following two conditions are met:
+
+   * The directive `session.cookie_domain` is set to an empty value. It may have been set directly in your [PHP configuration](http://php.net/manual/en/configuration.file.php) (`php.ini`), via the `\ini_set` method or via the `\session_set_cookie_params` method. You can check the value of that directive by executing the following statement somewhere in your application:
+
+     ```php
+     \var_dump(\ini_get('session.cookie_domain'));
+     ```
+
+   * Your application is accessed via a registered or registrable *domain name*, either by yourself during development and testing or by your visitors and users in production. That means your application is *not*, or *not only*, accessed via `localhost` or via an IP address.
+
+   Then the domain scope for the [two cookies](README.md#cookies) used by this library has changed. You can handle this change in one of two different ways:
+
+   * Restore the old behavior by placing the following statement as early as possible in your application, and before you create the `Auth` instance:
+
+     ```php
+     \ini_set('session.cookie_domain', \preg_replace('/^www\./', '', $_SERVER['HTTP_HOST']));
+     ```
+
+     You may also evaluate the complete second parameter and put its value directly into your [PHP configuration](http://php.net/manual/en/configuration.file.php) (`php.ini`).
+
+   * Use the new domain scope for your application. To do so, you only need to [rename the cookies](README.md#renaming-the-librarys-cookies) used by this library in order to prevent conflicts with old cookies that have been created previously. Renaming the cookies is critically important here. We recommend a versioned name such as `session_v1` for the session cookie.
+
+ * Only if *both* of the following two conditions are met:
+
+   * The directive `session.cookie_domain` is set to a value that starts with the `www` subdomain. It may have been set directly in your [PHP configuration](http://php.net/manual/en/configuration.file.php) (`php.ini`), via the `\ini_set` method or via the `\session_set_cookie_params` method. You can check the value of that directive by executing the following statement somewhere in your application:
+
+     ```php
+     \var_dump(\ini_get('session.cookie_domain'));
+     ```
+
+   * Your application is accessed via a registered or registrable *domain name*, either by yourself during development and testing or by your visitors and users in production. That means your application is *not*, or *not only*, accessed via `localhost` or via an IP address.
+
+   Then the domain scope for [one of the cookies](README.md#cookies) used by this library has changed. To make your application work correctly with the new scope, [rename the cookies](README.md#renaming-the-librarys-cookies) used by this library in order to prevent conflicts with old cookies that have been created previously. Renaming the cookies is critically important here. We recommend a versioned name such as `session_v1` for the session cookie.
+
+ * If the directive `session.cookie_path` is set to an empty value, then the path scope for [one of the cookies](README.md#cookies) used by this library has changed. To make your application work correctly with the new scope, [rename the cookies](README.md#renaming-the-librarys-cookies) used by this library in order to prevent conflicts with old cookies that have been created previously. Renaming the cookies is critically important here. We recommend a versioned name such as `session_v1` for the session cookie.
+
+   The directive may have been set directly in your [PHP configuration](http://php.net/manual/en/configuration.file.php) (`php.ini`), via the `\ini_set` method or via the `\session_set_cookie_params` method. You can check the value of that directive by executing the following statement somewhere in your application:
+
+   ```php
+   \var_dump(\ini_get('session.cookie_path'));
+   ```
+
+## From `v5.x.x` to `v6.x.x`
+
+ * The database schema has changed.
+
+   * The MySQL database schema has changed. Use the statements below to update your database:
 
      ```sql
-     ALTER TABLE `users` CHANGE `email` `email` VARCHAR(249) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL;
-     ALTER TABLE `users_confirmations` CHANGE `email` `email` VARCHAR(249) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL;
+     ALTER TABLE users
+         ADD COLUMN roles_mask INT(10) UNSIGNED NOT NULL DEFAULT 0 AFTER verified,
+         ADD COLUMN resettable TINYINT(1) UNSIGNED NOT NULL DEFAULT 1 AFTER verified;
 
-     -- ALTER DATABASE `<DATABASE_NAME>` CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;
+     ALTER TABLE users_confirmations
+         ADD COLUMN user_id INT(10) UNSIGNED NULL DEFAULT NULL AFTER id;
 
-     ALTER TABLE `users` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
-     ALTER TABLE `users_confirmations` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
-     ALTER TABLE `users_remembered` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
-     ALTER TABLE `users_resets` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
-     ALTER TABLE `users_throttling` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+     UPDATE users_confirmations SET user_id = (
+         SELECT id FROM users WHERE email = users_confirmations.email
+     ) WHERE user_id IS NULL;
 
-     ALTER TABLE `users` CHANGE `email` `email` VARCHAR(249) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL;
-     ALTER TABLE `users` CHANGE `username` `username` VARCHAR(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NULL DEFAULT NULL;
+     ALTER TABLE users_confirmations
+         CHANGE COLUMN user_id user_id INT(10) UNSIGNED NOT NULL;
 
-     ALTER TABLE `users_confirmations` CHANGE `email` `email` VARCHAR(249) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL;
+     ALTER TABLE users_confirmations
+         ADD INDEX user_id (user_id ASC);
 
-     ALTER TABLE `users_throttling` CHANGE `action_type` `action_type` ENUM('login','register','confirm_email') CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL;
+     DROP TABLE users_throttling;
 
-     REPAIR TABLE users;
-     OPTIMIZE TABLE users;
-     REPAIR TABLE users_confirmations;
-     OPTIMIZE TABLE users_confirmations;
-     REPAIR TABLE users_remembered;
-     OPTIMIZE TABLE users_remembered;
-     REPAIR TABLE users_resets;
-     OPTIMIZE TABLE users_resets;
-     REPAIR TABLE users_throttling;
-     OPTIMIZE TABLE users_throttling;
+     CREATE TABLE users_throttling (
+         bucket varchar(44) CHARACTER SET latin1 COLLATE latin1_general_cs NOT NULL,
+         tokens float unsigned NOT NULL,
+         replenished_at int(10) unsigned NOT NULL,
+         expires_at int(10) unsigned NOT NULL,
+         PRIMARY KEY (bucket),
+         KEY expires_at (expires_at)
+     ) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
      ```
+
+   * The SQLite database schema has changed. Use the statements below to update your database:
+
+     ```sql
+     ALTER TABLE users
+         ADD COLUMN "roles_mask" INTEGER NOT NULL CHECK ("roles_mask" >= 0) DEFAULT "0",
+         ADD COLUMN "resettable" INTEGER NOT NULL CHECK ("resettable" >= 0) DEFAULT "1";
+
+     ALTER TABLE users_confirmations
+         ADD COLUMN "user_id" INTEGER CHECK ("user_id" >= 0);
+
+     UPDATE users_confirmations SET user_id = (
+         SELECT id FROM users WHERE email = users_confirmations.email
+     ) WHERE user_id IS NULL;
+
+     CREATE INDEX "users_confirmations.user_id" ON "users_confirmations" ("user_id");
+
+     DROP TABLE users_throttling;
+
+     CREATE TABLE "users_throttling" (
+         "bucket" VARCHAR(44) PRIMARY KEY NOT NULL,
+         "tokens" REAL NOT NULL CHECK ("tokens" >= 0),
+         "replenished_at" INTEGER NOT NULL CHECK ("replenished_at" >= 0),
+         "expires_at" INTEGER NOT NULL CHECK ("expires_at" >= 0)
+     );
+
+     CREATE INDEX "users_throttling.expires_at" ON "users_throttling" ("expires_at");
+     ```
+
+ * The method `setThrottlingOptions` has been removed.
+
+ * The method `changePassword` may now throw an additional `\Delight\Auth\TooManyRequestsException` if too many attempts have been made without the correct old password.
+
+ * The two methods `confirmEmail` and `confirmEmailAndSignIn` may now throw an additional `\Delight\Auth\UserAlreadyExistsException` if an attempt has been made to change the email address to an address that has become occupied in the meantime.
+
+ * The two methods `forgotPassword` and `resetPassword` may now throw an additional `\Delight\Auth\ResetDisabledException` if the user has disabled password resets for their account.
+
+ * The `Base64` class is now an external module and has been moved from the namespace `Delight\Auth` to the namespace `Delight\Base64`. The interface and the return values are not compatible with those from previous versions anymore.
+
+## From `v4.x.x` to `v5.x.x`
+
+ * The MySQL database schema has changed. Use the statement below to update your database:
+
+   ```sql
+   ALTER TABLE `users` ADD COLUMN `status` TINYINT(2) UNSIGNED NOT NULL DEFAULT 0 AFTER `username`;
+   ```
+
+ * The two classes `Auth` and `Base64` are now `final`, i.e. they can't be extended anymore, which has never been a good idea, anyway. If you still need to wrap your own methods around these classes, consider [object composition instead of class inheritance](https://en.wikipedia.org/wiki/Composition_over_inheritance).
+
+## From `v3.x.x` to `v4.x.x`
+
+ * PHP 5.6.0 or higher is now required.
+
+## From `v2.x.x` to `v3.x.x`
+
+ * The license has been changed from the [Apache License 2.0](http://www.apache.org/licenses/LICENSE-2.0) to the [MIT License](https://opensource.org/licenses/MIT).
+
+## From `v1.x.x` to `v2.x.x`
+
+ * The MySQL schema has been changed from charset `utf8` to charset `utf8mb4` and from collation `utf8_general_ci` to collation `utf8mb4_unicode_ci`. Use the statements below to update the database schema:
+
+   ```sql
+   ALTER TABLE `users` CHANGE `email` `email` VARCHAR(249) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL;
+   ALTER TABLE `users_confirmations` CHANGE `email` `email` VARCHAR(249) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL;
+
+   -- ALTER DATABASE `<DATABASE_NAME>` CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;
+
+   ALTER TABLE `users` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+   ALTER TABLE `users_confirmations` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+   ALTER TABLE `users_remembered` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+   ALTER TABLE `users_resets` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+   ALTER TABLE `users_throttling` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+
+   ALTER TABLE `users` CHANGE `email` `email` VARCHAR(249) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL;
+   ALTER TABLE `users` CHANGE `username` `username` VARCHAR(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NULL DEFAULT NULL;
+
+   ALTER TABLE `users_confirmations` CHANGE `email` `email` VARCHAR(249) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL;
+
+   ALTER TABLE `users_throttling` CHANGE `action_type` `action_type` ENUM('login','register','confirm_email') CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL;
+
+   REPAIR TABLE users;
+   OPTIMIZE TABLE users;
+   REPAIR TABLE users_confirmations;
+   OPTIMIZE TABLE users_confirmations;
+   REPAIR TABLE users_remembered;
+   OPTIMIZE TABLE users_remembered;
+   REPAIR TABLE users_resets;
+   OPTIMIZE TABLE users_resets;
+   REPAIR TABLE users_throttling;
+   OPTIMIZE TABLE users_throttling;
+   ```

NOTICE

@@ -1,5 +0,0 @@
-PHP-Auth
-Copyright (c) delight.im <info@delight.im>
-
-This product includes software developed by
-delight.im (http://www.delight.im/).

composer.json

@@ -2,14 +2,16 @@
 	"name": "delight-im/auth",
 	"description": "Authentication for PHP. Simple, lightweight and secure.",
 	"require": {
-		"php": ">=5.5.0",
+		"php": ">=5.6.0",
 		"ext-openssl": "*",
-		"delight-im/cookie": "^1.3"
+		"delight-im/base64": "^1.0",
+		"delight-im/cookie": "^3.1",
+		"delight-im/db": "^1.2"
 	},
 	"type": "library",
 	"keywords": [ "auth", "authentication", "login", "security" ],
 	"homepage": "https://github.com/delight-im/PHP-Auth",
-	"license": "Apache-2.0",
+	"license": "MIT",
 	"autoload": {
 		"psr-4": {
 			"Delight\\Auth\\": "src/"

composer.lock

@@ -4,28 +4,68 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "hash": "32e4912115e164a1a86227d49db9ac29",
-    "content-hash": "1a5c0056d726ae6195da0faa38f37fdd",
+    "content-hash": "54d541ae3c5ba25b0cc06688d2b65467",
     "packages": [
         {
-            "name": "delight-im/cookie",
-            "version": "v1.3.0",
+            "name": "delight-im/base64",
+            "version": "v1.0.0",
             "source": {
                 "type": "git",
-                "url": "https://github.com/delight-im/PHP-Cookie.git",
-                "reference": "481c569d6f4bcb0391f56203f078d425b3339001"
+                "url": "https://github.com/delight-im/PHP-Base64.git",
+                "reference": "687b2a49f663e162030a8d27b32838bbe7f91c78"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/delight-im/PHP-Cookie/zipball/481c569d6f4bcb0391f56203f078d425b3339001",
-                "reference": "481c569d6f4bcb0391f56203f078d425b3339001",
+                "url": "https://api.github.com/repos/delight-im/PHP-Base64/zipball/687b2a49f663e162030a8d27b32838bbe7f91c78",
+                "reference": "687b2a49f663e162030a8d27b32838bbe7f91c78",
                 "shasum": ""
             },
             "require": {
-                "delight-im/http": "^1.1",
                 "php": ">=5.3.0"
             },
             "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "Delight\\Base64\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "description": "Simple and convenient Base64 encoding and decoding for PHP",
+            "homepage": "https://github.com/delight-im/PHP-Base64",
+            "keywords": [
+                "URL-safe",
+                "base-64",
+                "base64",
+                "decode",
+                "decoding",
+                "encode",
+                "encoding",
+                "url"
+            ],
+            "time": "2017-07-24T18:59:51+00:00"
+        },
+        {
+            "name": "delight-im/cookie",
+            "version": "v3.1.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/delight-im/PHP-Cookie.git",
+                "reference": "76ef2a21817cf7a034f85fc3f4d4bfc60f873947"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/delight-im/PHP-Cookie/zipball/76ef2a21817cf7a034f85fc3f4d4bfc60f873947",
+                "reference": "76ef2a21817cf7a034f85fc3f4d4bfc60f873947",
+                "shasum": ""
+            },
+            "require": {
+                "delight-im/http": "^2.0",
+                "php": ">=5.4.0"
+            },
+            "type": "library",
             "autoload": {
                 "psr-4": {
                     "Delight\\Cookie\\": "src/"
@@ -33,7 +73,7 @@
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
-                "Apache-2.0"
+                "MIT"
             ],
             "description": "Modern cookie management for PHP",
             "homepage": "https://github.com/delight-im/PHP-Cookie",
@@ -46,20 +86,61 @@
                 "samesite",
                 "xss"
             ],
-            "time": "2016-07-19 22:20:24"
+            "time": "2017-10-18T19:48:59+00:00"
         },
         {
-            "name": "delight-im/http",
-            "version": "v1.1.0",
+            "name": "delight-im/db",
+            "version": "v1.2.0",
             "source": {
                 "type": "git",
-                "url": "https://github.com/delight-im/PHP-HTTP.git",
-                "reference": "2ca9001f047c8b4e1b7ca7281823a1a9437850f8"
+                "url": "https://github.com/delight-im/PHP-DB.git",
+                "reference": "df99ef7c2e86c7ce206647ffe8ba74447c075b57"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/delight-im/PHP-HTTP/zipball/2ca9001f047c8b4e1b7ca7281823a1a9437850f8",
-                "reference": "2ca9001f047c8b4e1b7ca7281823a1a9437850f8",
+                "url": "https://api.github.com/repos/delight-im/PHP-DB/zipball/df99ef7c2e86c7ce206647ffe8ba74447c075b57",
+                "reference": "df99ef7c2e86c7ce206647ffe8ba74447c075b57",
+                "shasum": ""
+            },
+            "require": {
+                "ext-pdo": "*",
+                "php": ">=5.6.0"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "Delight\\Db\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "description": "Safe and convenient SQL database access in a driver-agnostic way",
+            "homepage": "https://github.com/delight-im/PHP-DB",
+            "keywords": [
+                "database",
+                "mysql",
+                "pdo",
+                "pgsql",
+                "postgresql",
+                "sql",
+                "sqlite"
+            ],
+            "time": "2017-03-18T20:51:59+00:00"
+        },
+        {
+            "name": "delight-im/http",
+            "version": "v2.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/delight-im/PHP-HTTP.git",
+                "reference": "0a19a72a7eac8b1301aa972fb20cff494ac43e09"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/delight-im/PHP-HTTP/zipball/0a19a72a7eac8b1301aa972fb20cff494ac43e09",
+                "reference": "0a19a72a7eac8b1301aa972fb20cff494ac43e09",
                 "shasum": ""
             },
             "require": {
@@ -73,7 +154,7 @@
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
-                "Apache-2.0"
+                "MIT"
             ],
             "description": "Hypertext Transfer Protocol (HTTP) utilities for PHP",
             "homepage": "https://github.com/delight-im/PHP-HTTP",
@@ -82,7 +163,7 @@
                 "http",
                 "https"
             ],
-            "time": "2016-07-08 21:19:02"
+            "time": "2016-07-21T15:05:01+00:00"
         }
     ],
     "packages-dev": [],
@@ -92,7 +173,7 @@
     "prefer-stable": false,
     "prefer-lowest": false,
     "platform": {
-        "php": ">=5.5.0",
+        "php": ">=5.6.0",
         "ext-openssl": "*"
     },
     "platform-dev": []

src/Administration.php

@@ -0,0 +1,529 @@
+<?php
+
+/*
+ * PHP-Auth (https://github.com/delight-im/PHP-Auth)
+ * Copyright (c) delight.im (https://www.delight.im/)
+ * Licensed under the MIT License (https://opensource.org/licenses/MIT)
+ */
+
+namespace Delight\Auth;
+
+use Delight\Db\PdoDatabase;
+use Delight\Db\Throwable\Error;
+
+require_once __DIR__ . '/Exceptions.php';
+
+/** Component that can be used for administrative tasks by privileged and authorized users */
+final class Administration extends UserManager {
+
+	/**
+	 * @internal
+	 *
+	 * @param PdoDatabase $databaseConnection the database connection to operate on
+	 * @param string|null $dbTablePrefix (optional) the prefix for the names of all database tables used by this component
+	 */
+	public function __construct(PdoDatabase $databaseConnection, $dbTablePrefix = null) {
+		parent::__construct($databaseConnection, $dbTablePrefix);
+	}
+
+	/**
+	 * Creates a new user
+	 *
+	 * @param string $email the email address to register
+	 * @param string $password the password for the new account
+	 * @param string|null $username (optional) the username that will be displayed
+	 * @return int the ID of the user that has been created (if any)
+	 * @throws InvalidEmailException if the email address was invalid
+	 * @throws InvalidPasswordException if the password was invalid
+	 * @throws UserAlreadyExistsException if a user with the specified email address already exists
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	public function createUser($email, $password, $username = null) {
+		return $this->createUserInternal(false, $email, $password, $username, null);
+	}
+
+	/**
+	 * Creates a new user while ensuring that the username is unique
+	 *
+	 * @param string $email the email address to register
+	 * @param string $password the password for the new account
+	 * @param string|null $username (optional) the username that will be displayed
+	 * @return int the ID of the user that has been created (if any)
+	 * @throws InvalidEmailException if the email address was invalid
+	 * @throws InvalidPasswordException if the password was invalid
+	 * @throws UserAlreadyExistsException if a user with the specified email address already exists
+	 * @throws DuplicateUsernameException if the specified username wasn't unique
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	public function createUserWithUniqueUsername($email, $password, $username = null) {
+		return $this->createUserInternal(true, $email, $password, $username, null);
+	}
+
+	/**
+	 * Deletes the user with the specified ID
+	 *
+	 * This action cannot be undone
+	 *
+	 * @param int $id the ID of the user to delete
+	 * @throws UnknownIdException if no user with the specified ID has been found
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	public function deleteUserById($id) {
+		$numberOfDeletedUsers = $this->deleteUsersByColumnValue('id', (int) $id);
+
+		if ($numberOfDeletedUsers === 0) {
+			throw new UnknownIdException();
+		}
+	}
+
+	/**
+	 * Deletes the user with the specified email address
+	 *
+	 * This action cannot be undone
+	 *
+	 * @param string $email the email address of the user to delete
+	 * @throws InvalidEmailException if no user with the specified email address has been found
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	public function deleteUserByEmail($email) {
+		$email = self::validateEmailAddress($email);
+
+		$numberOfDeletedUsers = $this->deleteUsersByColumnValue('email', $email);
+
+		if ($numberOfDeletedUsers === 0) {
+			throw new InvalidEmailException();
+		}
+	}
+
+	/**
+	 * Deletes the user with the specified username
+	 *
+	 * This action cannot be undone
+	 *
+	 * @param string $username the username of the user to delete
+	 * @throws UnknownUsernameException if no user with the specified username has been found
+	 * @throws AmbiguousUsernameException if multiple users with the specified username have been found
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	public function deleteUserByUsername($username) {
+		$userData = $this->getUserDataByUsername(
+			\trim($username),
+			[ 'id' ]
+		);
+
+		$this->deleteUsersByColumnValue('id', (int) $userData['id']);
+	}
+
+	/**
+	 * Assigns the specified role to the user with the given ID
+	 *
+	 * A user may have any number of roles (i.e. no role at all, a single role, or any combination of roles)
+	 *
+	 * @param int $userId the ID of the user to assign the role to
+	 * @param int $role the role as one of the constants from the {@see Role} class
+	 * @throws UnknownIdException if no user with the specified ID has been found
+	 *
+	 * @see Role
+	 */
+	public function addRoleForUserById($userId, $role) {
+		$userFound = $this->addRoleForUserByColumnValue(
+			'id',
+			(int) $userId,
+			$role
+		);
+
+		if ($userFound === false) {
+			throw new UnknownIdException();
+		}
+	}
+
+	/**
+	 * Assigns the specified role to the user with the given email address
+	 *
+	 * A user may have any number of roles (i.e. no role at all, a single role, or any combination of roles)
+	 *
+	 * @param string $userEmail the email address of the user to assign the role to
+	 * @param int $role the role as one of the constants from the {@see Role} class
+	 * @throws InvalidEmailException if no user with the specified email address has been found
+	 *
+	 * @see Role
+	 */
+	public function addRoleForUserByEmail($userEmail, $role) {
+		$userEmail = self::validateEmailAddress($userEmail);
+
+		$userFound = $this->addRoleForUserByColumnValue(
+			'email',
+			$userEmail,
+			$role
+		);
+
+		if ($userFound === false) {
+			throw new InvalidEmailException();
+		}
+	}
+
+	/**
+	 * Assigns the specified role to the user with the given username
+	 *
+	 * A user may have any number of roles (i.e. no role at all, a single role, or any combination of roles)
+	 *
+	 * @param string $username the username of the user to assign the role to
+	 * @param int $role the role as one of the constants from the {@see Role} class
+	 * @throws UnknownUsernameException if no user with the specified username has been found
+	 * @throws AmbiguousUsernameException if multiple users with the specified username have been found
+	 *
+	 * @see Role
+	 */
+	public function addRoleForUserByUsername($username, $role) {
+		$userData = $this->getUserDataByUsername(
+			\trim($username),
+			[ 'id' ]
+		);
+
+		$this->addRoleForUserByColumnValue(
+			'id',
+			(int) $userData['id'],
+			$role
+		);
+	}
+
+	/**
+	 * Takes away the specified role from the user with the given ID
+	 *
+	 * A user may have any number of roles (i.e. no role at all, a single role, or any combination of roles)
+	 *
+	 * @param int $userId the ID of the user to take the role away from
+	 * @param int $role the role as one of the constants from the {@see Role} class
+	 * @throws UnknownIdException if no user with the specified ID has been found
+	 *
+	 * @see Role
+	 */
+	public function removeRoleForUserById($userId, $role) {
+		$userFound = $this->removeRoleForUserByColumnValue(
+			'id',
+			(int) $userId,
+			$role
+		);
+
+		if ($userFound === false) {
+			throw new UnknownIdException();
+		}
+	}
+
+	/**
+	 * Takes away the specified role from the user with the given email address
+	 *
+	 * A user may have any number of roles (i.e. no role at all, a single role, or any combination of roles)
+	 *
+	 * @param string $userEmail the email address of the user to take the role away from
+	 * @param int $role the role as one of the constants from the {@see Role} class
+	 * @throws InvalidEmailException if no user with the specified email address has been found
+	 *
+	 * @see Role
+	 */
+	public function removeRoleForUserByEmail($userEmail, $role) {
+		$userEmail = self::validateEmailAddress($userEmail);
+
+		$userFound = $this->removeRoleForUserByColumnValue(
+			'email',
+			$userEmail,
+			$role
+		);
+
+		if ($userFound === false) {
+			throw new InvalidEmailException();
+		}
+	}
+
+	/**
+	 * Takes away the specified role from the user with the given username
+	 *
+	 * A user may have any number of roles (i.e. no role at all, a single role, or any combination of roles)
+	 *
+	 * @param string $username the username of the user to take the role away from
+	 * @param int $role the role as one of the constants from the {@see Role} class
+	 * @throws UnknownUsernameException if no user with the specified username has been found
+	 * @throws AmbiguousUsernameException if multiple users with the specified username have been found
+	 *
+	 * @see Role
+	 */
+	public function removeRoleForUserByUsername($username, $role) {
+		$userData = $this->getUserDataByUsername(
+			\trim($username),
+			[ 'id' ]
+		);
+
+		$this->removeRoleForUserByColumnValue(
+			'id',
+			(int) $userData['id'],
+			$role
+		);
+	}
+
+	/**
+	 * Returns whether the user with the given ID has the specified role
+	 *
+	 * @param int $userId the ID of the user to check the roles for
+	 * @param int $role the role as one of the constants from the {@see Role} class
+	 * @return bool
+	 * @throws UnknownIdException if no user with the specified ID has been found
+	 *
+	 * @see Role
+	 */
+	public function doesUserHaveRole($userId, $role) {
+		$userId = (int) $userId;
+		$role = (int) $role;
+
+		$rolesBitmask = $this->db->selectValue(
+			'SELECT roles_mask FROM ' . $this->dbTablePrefix . 'users WHERE id = ?',
+			[ $userId ]
+		);
+
+		if ($rolesBitmask === null) {
+			throw new UnknownIdException();
+		}
+
+		return ($rolesBitmask & $role) === $role;
+	}
+
+	/**
+	 * Returns the roles of the user with the given ID, mapping the numerical values to their descriptive names
+	 *
+	 * @param int $userId the ID of the user to return the roles for
+	 * @return array
+	 * @throws UnknownIdException if no user with the specified ID has been found
+	 *
+	 * @see Role
+	 */
+	public function getRolesForUserById($userId) {
+		$userId = (int) $userId;
+
+		$rolesBitmask = $this->db->selectValue(
+			'SELECT roles_mask FROM ' . $this->dbTablePrefix . 'users WHERE id = ?',
+			[ $userId ]
+		);
+
+		if ($rolesBitmask === null) {
+			throw new UnknownIdException();
+		}
+
+		return \array_filter(
+			Role::getMap(),
+			function ($each) use ($rolesBitmask) {
+				return ($rolesBitmask & $each) === $each;
+			},
+			\ARRAY_FILTER_USE_KEY
+		);
+	}
+
+	/**
+	 * Signs in as the user with the specified ID
+	 *
+	 * @param int $id the ID of the user to sign in as
+	 * @throws UnknownIdException if no user with the specified ID has been found
+	 * @throws EmailNotVerifiedException if the user has not verified their email address via a confirmation method yet
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	public function logInAsUserById($id) {
+		$numberOfMatchedUsers = $this->logInAsUserByColumnValue('id', (int) $id);
+
+		if ($numberOfMatchedUsers === 0) {
+			throw new UnknownIdException();
+		}
+	}
+
+	/**
+	 * Signs in as the user with the specified email address
+	 *
+	 * @param string $email the email address of the user to sign in as
+	 * @throws InvalidEmailException if no user with the specified email address has been found
+	 * @throws EmailNotVerifiedException if the user has not verified their email address via a confirmation method yet
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	public function logInAsUserByEmail($email) {
+		$email = self::validateEmailAddress($email);
+
+		$numberOfMatchedUsers = $this->logInAsUserByColumnValue('email', $email);
+
+		if ($numberOfMatchedUsers === 0) {
+			throw new InvalidEmailException();
+		}
+	}
+
+	/**
+	 * Signs in as the user with the specified display name
+	 *
+	 * @param string $username the display name of the user to sign in as
+	 * @throws UnknownUsernameException if no user with the specified username has been found
+	 * @throws AmbiguousUsernameException if multiple users with the specified username have been found
+	 * @throws EmailNotVerifiedException if the user has not verified their email address via a confirmation method yet
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	public function logInAsUserByUsername($username) {
+		$numberOfMatchedUsers = $this->logInAsUserByColumnValue('username', \trim($username));
+
+		if ($numberOfMatchedUsers === 0) {
+			throw new UnknownUsernameException();
+		}
+		elseif ($numberOfMatchedUsers > 1) {
+			throw new AmbiguousUsernameException();
+		}
+	}
+
+	/**
+	 * Deletes all existing users where the column with the specified name has the given value
+	 *
+	 * You must never pass untrusted input to the parameter that takes the column name
+	 *
+	 * @param string $columnName the name of the column to filter by
+	 * @param mixed $columnValue the value to look for in the selected column
+	 * @return int the number of deleted users
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	private function deleteUsersByColumnValue($columnName, $columnValue) {
+		try {
+			return $this->db->delete(
+				$this->dbTablePrefix . 'users',
+				[
+					$columnName => $columnValue
+				]
+			);
+		}
+		catch (Error $e) {
+			throw new DatabaseError();
+		}
+	}
+
+	/**
+	 * Modifies the roles for the user where the column with the specified name has the given value
+	 *
+	 * You must never pass untrusted input to the parameter that takes the column name
+	 *
+	 * @param string $columnName the name of the column to filter by
+	 * @param mixed $columnValue the value to look for in the selected column
+	 * @param callable $modification the modification to apply to the existing bitmask of roles
+	 * @return bool whether any user with the given column constraints has been found
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 *
+	 * @see Role
+	 */
+	private function modifyRolesForUserByColumnValue($columnName, $columnValue, callable $modification) {
+		try {
+			$userData = $this->db->selectRow(
+				'SELECT id, roles_mask FROM ' . $this->dbTablePrefix . 'users WHERE ' . $columnName . ' = ?',
+				[ $columnValue ]
+			);
+		}
+		catch (Error $e) {
+			throw new DatabaseError();
+		}
+
+		if ($userData === null) {
+			return false;
+		}
+
+		$newRolesBitmask = $modification($userData['roles_mask']);
+
+		try {
+			$this->db->exec(
+				'UPDATE ' . $this->dbTablePrefix . 'users SET roles_mask = ? WHERE id = ?',
+				[
+					$newRolesBitmask,
+					(int) $userData['id']
+				]
+			);
+
+			return true;
+		}
+		catch (Error $e) {
+			throw new DatabaseError();
+		}
+	}
+
+	/**
+	 * Assigns the specified role to the user where the column with the specified name has the given value
+	 *
+	 * You must never pass untrusted input to the parameter that takes the column name
+	 *
+	 * @param string $columnName the name of the column to filter by
+	 * @param mixed $columnValue the value to look for in the selected column
+	 * @param int $role the role as one of the constants from the {@see Role} class
+	 * @return bool whether any user with the given column constraints has been found
+	 *
+	 * @see Role
+	 */
+	private function addRoleForUserByColumnValue($columnName, $columnValue, $role) {
+		$role = (int) $role;
+
+		return $this->modifyRolesForUserByColumnValue(
+			$columnName,
+			$columnValue,
+			function ($oldRolesBitmask) use ($role) {
+				return $oldRolesBitmask | $role;
+			}
+		);
+	}
+
+	/**
+	 * Takes away the specified role from the user where the column with the specified name has the given value
+	 *
+	 * You must never pass untrusted input to the parameter that takes the column name
+	 *
+	 * @param string $columnName the name of the column to filter by
+	 * @param mixed $columnValue the value to look for in the selected column
+	 * @param int $role the role as one of the constants from the {@see Role} class
+	 * @return bool whether any user with the given column constraints has been found
+	 *
+	 * @see Role
+	 */
+	private function removeRoleForUserByColumnValue($columnName, $columnValue, $role) {
+		$role = (int) $role;
+
+		return $this->modifyRolesForUserByColumnValue(
+			$columnName,
+			$columnValue,
+			function ($oldRolesBitmask) use ($role) {
+				return $oldRolesBitmask & ~$role;
+			}
+		);
+	}
+
+	/**
+	 * Signs in as the user for which the column with the specified name has the given value
+	 *
+	 * You must never pass untrusted input to the parameter that takes the column name
+	 *
+	 * @param string $columnName the name of the column to filter by
+	 * @param mixed $columnValue the value to look for in the selected column
+	 * @return int the number of matched users (where only a value of one means that the login may have been successful)
+	 * @throws EmailNotVerifiedException if the user has not verified their email address via a confirmation method yet
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	private function logInAsUserByColumnValue($columnName, $columnValue) {
+		try {
+			$users = $this->db->select(
+				'SELECT verified, id, email, username, status, roles_mask FROM ' . $this->dbTablePrefix . 'users WHERE ' . $columnName . ' = ? LIMIT 2 OFFSET 0',
+				[ $columnValue ]
+			);
+		}
+		catch (Error $e) {
+			throw new DatabaseError();
+		}
+
+		$numberOfMatchingUsers = \count($users);
+
+		if ($numberOfMatchingUsers === 1) {
+			$user = $users[0];
+
+			if ((int) $user['verified'] === 1) {
+				$this->onLoginSuccessful($user['id'], $user['email'], $user['username'], $user['status'], $user['roles_mask'], false);
+			}
+			else {
+				throw new EmailNotVerifiedException();
+			}
+		}
+
+		return $numberOfMatchingUsers;
+	}
+
+}

src/Base64.php

@@ -1,44 +0,0 @@
-<?php
-
-/*
- * Copyright (c) delight.im <info@delight.im>
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-namespace Delight\Auth;
-
-class Base64 {
-
-	const SPECIAL_CHARS_ORIGINAL = '+/=';
-	const SPECIAL_CHARS_SAFE = '._-';
-
-	public static function encode($data, $safeChars = false) {
-		$result = base64_encode($data);
-
-		if ($safeChars) {
-			$result = strtr($result, self::SPECIAL_CHARS_ORIGINAL, self::SPECIAL_CHARS_SAFE);
-		}
-
-		return $result;
-	}
-
-	public static function decode($data) {
-		$data = strtr($data, self::SPECIAL_CHARS_SAFE, self::SPECIAL_CHARS_ORIGINAL);
-
-		$result = base64_decode($data, true);
-
-		return $result;
-	}
-
-}

src/Exceptions.php

@@ -1,27 +1,21 @@
 <?php
 
 /*
- * Copyright (c) delight.im <info@delight.im>
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * PHP-Auth (https://github.com/delight-im/PHP-Auth)
+ * Copyright (c) delight.im (https://www.delight.im/)
+ * Licensed under the MIT License (https://opensource.org/licenses/MIT)
  */
 
 namespace Delight\Auth;
 
 class AuthException extends \Exception {}
 
+class UnknownIdException extends AuthException {}
+
 class InvalidEmailException extends AuthException {}
 
+class UnknownUsernameException extends AuthException {}
+
 class InvalidPasswordException extends AuthException {}
 
 class EmailNotVerifiedException extends AuthException {}
@@ -36,10 +30,24 @@ class TokenExpiredException extends AuthException {}
 
 class TooManyRequestsException extends AuthException {}
 
+class DuplicateUsernameException extends AuthException {}
+
+class AmbiguousUsernameException extends AuthException {}
+
+class AttemptCancelledException extends AuthException {}
+
+class ResetDisabledException extends AuthException {}
+
+class ConfirmationRequestNotFound extends AuthException {}
+
 class AuthError extends \Exception {}
 
 class DatabaseError extends AuthError {}
 
+class DatabaseDriverError extends DatabaseError {}
+
 class MissingCallbackError extends AuthError {}
 
 class HeadersAlreadySentError extends AuthError {}
+
+class EmailOrUsernameRequiredError extends AuthError {}

src/Role.php

@@ -0,0 +1,79 @@
+<?php
+
+/*
+ * PHP-Auth (https://github.com/delight-im/PHP-Auth)
+ * Copyright (c) delight.im (https://www.delight.im/)
+ * Licensed under the MIT License (https://opensource.org/licenses/MIT)
+ */
+
+namespace Delight\Auth;
+
+final class Role {
+
+	const ADMIN = 1;
+	const AUTHOR = 2;
+	const COLLABORATOR = 4;
+	const CONSULTANT = 8;
+	const CONSUMER = 16;
+	const CONTRIBUTOR = 32;
+	const COORDINATOR = 64;
+	const CREATOR = 128;
+	const DEVELOPER = 256;
+	const DIRECTOR = 512;
+	const EDITOR = 1024;
+	const EMPLOYEE = 2048;
+	const MAINTAINER = 4096;
+	const MANAGER = 8192;
+	const MODERATOR = 16384;
+	const PUBLISHER = 32768;
+	const REVIEWER = 65536;
+	const SUBSCRIBER = 131072;
+	const SUPER_ADMIN = 262144;
+	const SUPER_EDITOR = 524288;
+	const SUPER_MODERATOR = 1048576;
+	const TRANSLATOR = 2097152;
+	// const XYZ = 4194304;
+	// const XYZ = 8388608;
+	// const XYZ = 16777216;
+	// const XYZ = 33554432;
+	// const XYZ = 67108864;
+	// const XYZ = 134217728;
+	// const XYZ = 268435456;
+	// const XYZ = 536870912;
+
+	/**
+	 * Returns an array mapping the numerical role values to their descriptive names
+	 *
+	 * @return array
+	 */
+	public static function getMap() {
+		$reflectionClass = new \ReflectionClass(static::class);
+
+		return \array_flip($reflectionClass->getConstants());
+	}
+
+	/**
+	 * Returns the descriptive role names
+	 *
+	 * @return string[]
+	 */
+	public static function getNames() {
+		$reflectionClass = new \ReflectionClass(static::class);
+
+		return \array_keys($reflectionClass->getConstants());
+	}
+
+	/**
+	 * Returns the numerical role values
+	 *
+	 * @return int[]
+	 */
+	public static function getValues() {
+		$reflectionClass = new \ReflectionClass(static::class);
+
+		return \array_values($reflectionClass->getConstants());
+	}
+
+	private function __construct() {}
+
+}

src/Status.php

@@ -0,0 +1,20 @@
+<?php
+
+/*
+ * PHP-Auth (https://github.com/delight-im/PHP-Auth)
+ * Copyright (c) delight.im (https://www.delight.im/)
+ * Licensed under the MIT License (https://opensource.org/licenses/MIT)
+ */
+
+namespace Delight\Auth;
+
+final class Status {
+
+	const NORMAL = 0;
+	const ARCHIVED = 1;
+	const BANNED = 2;
+	const LOCKED = 3;
+	const PENDING_REVIEW = 4;
+	const SUSPENDED = 5;
+
+}

src/UserManager.php

@@ -0,0 +1,336 @@
+<?php
+
+/*
+ * PHP-Auth (https://github.com/delight-im/PHP-Auth)
+ * Copyright (c) delight.im (https://www.delight.im/)
+ * Licensed under the MIT License (https://opensource.org/licenses/MIT)
+ */
+
+namespace Delight\Auth;
+
+use Delight\Base64\Base64;
+use Delight\Cookie\Session;
+use Delight\Db\PdoDatabase;
+use Delight\Db\PdoDsn;
+use Delight\Db\Throwable\Error;
+use Delight\Db\Throwable\IntegrityConstraintViolationException;
+
+require_once __DIR__ . '/Exceptions.php';
+
+/**
+ * Abstract base class for components implementing user management
+ *
+ * @internal
+ */
+abstract class UserManager {
+
+	/** @var string session field for whether the client is currently signed in */
+	const SESSION_FIELD_LOGGED_IN = 'auth_logged_in';
+	/** @var string session field for the ID of the user who is currently signed in (if any) */
+	const SESSION_FIELD_USER_ID = 'auth_user_id';
+	/** @var string session field for the email address of the user who is currently signed in (if any) */
+	const SESSION_FIELD_EMAIL = 'auth_email';
+	/** @var string session field for the display name (if any) of the user who is currently signed in (if any) */
+	const SESSION_FIELD_USERNAME = 'auth_username';
+	/** @var string session field for the status of the user who is currently signed in (if any) as one of the constants from the {@see Status} class */
+	const SESSION_FIELD_STATUS = 'auth_status';
+	/** @var string session field for the roles of the user who is currently signed in (if any) as a bitmask using constants from the {@see Role} class */
+	const SESSION_FIELD_ROLES = 'auth_roles';
+	/** @var string session field for whether the user who is currently signed in (if any) has been remembered (instead of them having authenticated actively) */
+	const SESSION_FIELD_REMEMBERED = 'auth_remembered';
+
+	/** @var PdoDatabase the database connection to operate on */
+	protected $db;
+	/** @var string the prefix for the names of all database tables used by this component */
+	protected $dbTablePrefix;
+
+	/**
+	 * Creates a random string with the given maximum length
+	 *
+	 * With the default parameter, the output should contain at least as much randomness as a UUID
+	 *
+	 * @param int $maxLength the maximum length of the output string (integer multiple of 4)
+	 * @return string the new random string
+	 */
+	public static function createRandomString($maxLength = 24) {
+		// calculate how many bytes of randomness we need for the specified string length
+		$bytes = \floor((int) $maxLength / 4) * 3;
+
+		// get random data
+		$data = \openssl_random_pseudo_bytes($bytes);
+
+		// return the Base64-encoded result
+		return Base64::encodeUrlSafe($data);
+	}
+
+	/**
+	 * @param PdoDatabase|PdoDsn|\PDO $databaseConnection the database connection to operate on
+	 * @param string|null $dbTablePrefix (optional) the prefix for the names of all database tables used by this component
+	 */
+	protected function __construct($databaseConnection, $dbTablePrefix = null) {
+		if ($databaseConnection instanceof PdoDatabase) {
+			$this->db = $databaseConnection;
+		}
+		elseif ($databaseConnection instanceof PdoDsn) {
+			$this->db = PdoDatabase::fromDsn($databaseConnection);
+		}
+		elseif ($databaseConnection instanceof \PDO) {
+			$this->db = PdoDatabase::fromPdo($databaseConnection, true);
+		}
+		else {
+			$this->db = null;
+
+			throw new \InvalidArgumentException('The database connection must be an instance of either `PdoDatabase`, `PdoDsn` or `PDO`');
+		}
+
+		$this->dbTablePrefix = (string) $dbTablePrefix;
+	}
+
+	/**
+	 * Creates a new user
+	 *
+	 * If you want the user's account to be activated by default, pass `null` as the callback
+	 *
+	 * If you want to make the user verify their email address first, pass an anonymous function as the callback
+	 *
+	 * The callback function must have the following signature:
+	 *
+	 * `function ($selector, $token)`
+	 *
+	 * Both pieces of information must be sent to the user, usually embedded in a link
+	 *
+	 * When the user wants to verify their email address as a next step, both pieces will be required again
+	 *
+	 * @param bool $requireUniqueUsername whether it must be ensured that the username is unique
+	 * @param string $email the email address to register
+	 * @param string $password the password for the new account
+	 * @param string|null $username (optional) the username that will be displayed
+	 * @param callable|null $callback (optional) the function that sends the confirmation email to the user
+	 * @return int the ID of the user that has been created (if any)
+	 * @throws InvalidEmailException if the email address has been invalid
+	 * @throws InvalidPasswordException if the password has been invalid
+	 * @throws UserAlreadyExistsException if a user with the specified email address already exists
+	 * @throws DuplicateUsernameException if it was specified that the username must be unique while it was *not*
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 *
+	 * @see confirmEmail
+	 * @see confirmEmailAndSignIn
+	 */
+	protected function createUserInternal($requireUniqueUsername, $email, $password, $username = null, callable $callback = null) {
+		\ignore_user_abort(true);
+
+		$email = self::validateEmailAddress($email);
+		$password = self::validatePassword($password);
+
+		$username = isset($username) ? \trim($username) : null;
+
+		// if the supplied username is the empty string or has consisted of whitespace only
+		if ($username === '') {
+			// this actually means that there is no username
+			$username = null;
+		}
+
+		// if the uniqueness of the username is to be ensured
+		if ($requireUniqueUsername) {
+			// if a username has actually been provided
+			if ($username !== null) {
+				// count the number of users who do already have that specified username
+				$occurrencesOfUsername = $this->db->selectValue(
+					'SELECT COUNT(*) FROM ' . $this->dbTablePrefix . 'users WHERE username = ?',
+					[ $username ]
+				);
+
+				// if any user with that username does already exist
+				if ($occurrencesOfUsername > 0) {
+					// cancel the operation and report the violation of this requirement
+					throw new DuplicateUsernameException();
+				}
+			}
+		}
+
+		$password = \password_hash($password, \PASSWORD_DEFAULT);
+		$verified = \is_callable($callback) ? 0 : 1;
+
+		try {
+			$this->db->insert(
+				$this->dbTablePrefix . 'users',
+				[
+					'email' => $email,
+					'password' => $password,
+					'username' => $username,
+					'verified' => $verified,
+					'registered' => \time()
+				]
+			);
+		}
+		// if we have a duplicate entry
+		catch (IntegrityConstraintViolationException $e) {
+			throw new UserAlreadyExistsException();
+		}
+		catch (Error $e) {
+			throw new DatabaseError();
+		}
+
+		$newUserId = (int) $this->db->getLastInsertId();
+
+		if ($verified === 0) {
+			$this->createConfirmationRequest($newUserId, $email, $callback);
+		}
+
+		return $newUserId;
+	}
+
+	/**
+	 * Called when a user has successfully logged in
+	 *
+	 * This may happen via the standard login, via the "remember me" feature, or due to impersonation by administrators
+	 *
+	 * @param int $userId the ID of the user
+	 * @param string $email the email address of the user
+	 * @param string $username the display name (if any) of the user
+	 * @param int $status the status of the user as one of the constants from the {@see Status} class
+	 * @param int $roles the roles of the user as a bitmask using constants from the {@see Role} class
+	 * @param bool $remembered whether the user has been remembered (instead of them having authenticated actively)
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	protected function onLoginSuccessful($userId, $email, $username, $status, $roles, $remembered) {
+		// re-generate the session ID to prevent session fixation attacks (requests a cookie to be written on the client)
+		Session::regenerate(true);
+
+		// save the user data in the session variables maintained by this library
+		$_SESSION[self::SESSION_FIELD_LOGGED_IN] = true;
+		$_SESSION[self::SESSION_FIELD_USER_ID] = (int) $userId;
+		$_SESSION[self::SESSION_FIELD_EMAIL] = $email;
+		$_SESSION[self::SESSION_FIELD_USERNAME] = $username;
+		$_SESSION[self::SESSION_FIELD_STATUS] = (int) $status;
+		$_SESSION[self::SESSION_FIELD_ROLES] = (int) $roles;
+		$_SESSION[self::SESSION_FIELD_REMEMBERED] = $remembered;
+	}
+
+	/**
+	 * Returns the requested user data for the account with the specified username (if any)
+	 *
+	 * You must never pass untrusted input to the parameter that takes the column list
+	 *
+	 * @param string $username the username to look for
+	 * @param array $requestedColumns the columns to request from the user's record
+	 * @return array the user data (if an account was found unambiguously)
+	 * @throws UnknownUsernameException if no user with the specified username has been found
+	 * @throws AmbiguousUsernameException if multiple users with the specified username have been found
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	protected function getUserDataByUsername($username, array $requestedColumns) {
+		try {
+			$projection = \implode(', ', $requestedColumns);
+
+			$users = $this->db->select(
+				'SELECT ' . $projection . ' FROM ' . $this->dbTablePrefix . 'users WHERE username = ? LIMIT 2 OFFSET 0',
+				[ $username ]
+			);
+		}
+		catch (Error $e) {
+			throw new DatabaseError();
+		}
+
+		if (empty($users)) {
+			throw new UnknownUsernameException();
+		}
+		else {
+			if (\count($users) === 1) {
+				return $users[0];
+			}
+			else {
+				throw new AmbiguousUsernameException();
+			}
+		}
+	}
+
+	/**
+	 * Validates an email address
+	 *
+	 * @param string $email the email address to validate
+	 * @return string the sanitized email address
+	 * @throws InvalidEmailException if the email address has been invalid
+	 */
+	protected static function validateEmailAddress($email) {
+		if (empty($email)) {
+			throw new InvalidEmailException();
+		}
+
+		$email = \trim($email);
+
+		if (!\filter_var($email, \FILTER_VALIDATE_EMAIL)) {
+			throw new InvalidEmailException();
+		}
+
+		return $email;
+	}
+
+	/**
+	 * Validates a password
+	 *
+	 * @param string $password the password to validate
+	 * @return string the sanitized password
+	 * @throws InvalidPasswordException if the password has been invalid
+	 */
+	protected static function validatePassword($password) {
+		if (empty($password)) {
+			throw new InvalidPasswordException();
+		}
+
+		$password = \trim($password);
+
+		if (\strlen($password) < 1) {
+			throw new InvalidPasswordException();
+		}
+
+		return $password;
+	}
+
+	/**
+	 * Creates a request for email confirmation
+	 *
+	 * The callback function must have the following signature:
+	 *
+	 * `function ($selector, $token)`
+	 *
+	 * Both pieces of information must be sent to the user, usually embedded in a link
+	 *
+	 * When the user wants to verify their email address as a next step, both pieces will be required again
+	 *
+	 * @param int $userId the user's ID
+	 * @param string $email the email address to verify
+	 * @param callable $callback the function that sends the confirmation email to the user
+	 * @throws AuthError if an internal problem occurred (do *not* catch)
+	 */
+	protected function createConfirmationRequest($userId, $email, callable $callback) {
+		$selector = self::createRandomString(16);
+		$token = self::createRandomString(16);
+		$tokenHashed = \password_hash($token, \PASSWORD_DEFAULT);
+		$expires = \time() + 60 * 60 * 24;
+
+		try {
+			$this->db->insert(
+				$this->dbTablePrefix . 'users_confirmations',
+				[
+					'user_id' => (int) $userId,
+					'email' => $email,
+					'selector' => $selector,
+					'token' => $tokenHashed,
+					'expires' => $expires
+				]
+			);
+		}
+		catch (Error $e) {
+			throw new DatabaseError();
+		}
+
+		if (\is_callable($callback)) {
+			$callback($selector, $token);
+		}
+		else {
+			throw new MissingCallbackError();
+		}
+	}
+
+}