Tương tác giữa PHP và jQuery - part 22 docx

CHAPTER 6 ■ PASSWORD PROTECTION SENSITIVE ACTIONS AND AREAS 211 $obj = new Admin($dbo); // Load a hash of the word test and output it $hash1 = $obj->testSaltedHash("test"); echo "Hash 1 without a salt:<br />", $hash1, "<br /><br />"; // Pause execution for a second to get a different timestamp sleep(1); // Load a second hash of the word test $hash2 = $obj->testSaltedHash("test"); echo "Hash 2 without a salt:<br />", $hash2, "<br /><br />"; // Pause execution for a second to get a different timestamp sleep(1); // Rehash the word test with the existing salt $hash3 = $obj->testSaltedHash("test", $hash2); echo "Hash 3 with the salt from hash 2:<br />", $hash3; ?> ■ Note The sleep() function delays execution of a script by a given number of seconds, passed as its sole argument. You can learn more about this function at http://php.net/sleep. Your results will not be identical because the timestamp hashes used for the salt will differ; however, your results should look something like this: Hash 1 without a salt: 518fd85bb85815af85e88b7c43d892238af9a5ca5775807 Hash 2 without a salt: 93b14e3f42ca09cafc1330b592669a5d02e9815bc2f69de Hash 3 with the salt from hash 2: 93b14e3f42ca09cafc1330b592669a5d02e9815bc2f69de CHAPTER 6 ■ PASSWORD PROTECTION SENSITIVE ACTIONS AND AREAS 212 As you can see, hashes of the word test don’t match up when passed separately; however, if you supply an existing salted hash of test, the same hash is produced. This way, even if two users have the same password, their stored hashes will be different, making it much more difficult for potential attackers to crack passwords. ■ Note Bear in mind that no algorithm is 100% effective. However, using techniques like salted hashes makes it possible to reduce the possibility of an attack significantly. Creating a User to Test Administrative Access In order to test the administrative functions, you’ll need a username/password pair to exist in your users table. For simplicity, the username will be testuser, the password will be admin, and the email address will be admin@example.com. Keep in mind that this is not a secure password; it is being used for illustration purposes only, and it should be changed before you use it with any production scripts. Begin by generating a hash of the password, admin, which is easy using the test method testSaltedHash() and test.php. Add the following bold code to test.php to generate a salted hash of your test user’s password: <?php // Include necessary files include_once ' /sys/core/init.inc.php'; // Load the admin object $obj = new Admin($dbo); // Generate a salted hash of "admin" $pass = $obj->testSaltedHash("admin"); echo 'Hash of "admin":<br />', $pass, "<br /><br />"; ?> Navigate to http://localhost/test.php, and you’ll see output similar to the following: Hash of "admin": a1645e41f29c45c46539192fe29627751e1838f7311eeb4 Copy the hash, navigate to http://localhost/phpmyadmin, and then click the SQL tab. Execute the following query to insert a test user into the table: INSERT INTO `php-jquery_example`.`users` (`user_name`, `user_pass`, `user_email`) VALUES CHAPTER 6 ■ PASSWORD PROTECTION SENSITIVE ACTIONS AND AREAS 213 ( 'testuser', 'a1645e41f29c45c46539192fe29627751e1838f7311eeb4', 'admin@example.com' ); After executing the preceding code, click the php-jquery_example database, and then the users table. Select the Browse tab to view the user info in the table (see Figure 6-3). Figure 6-3. The test user data after inserting it into the database Now that a user exists in the user database with a salted hash stored, you can delete both the testSaltedHash() method from the Admin class and the entire test.php file. Modifying the App to Handle the Login Form Submission At this point, you’re almost ready to test a user login. Before it will work, however, you need to modify process.inc.php to handle form submissions from the login form. Due to the way the file is set up, this change is as simple as adding a new element to the $actions array. Open process.inc.php and insert the following bold code: <?php /* CHAPTER 6 ■ PASSWORD PROTECTION SENSITIVE ACTIONS AND AREAS 214 * Enable sessions */ session_start(); /* * Include necessary files */ include_once ' / / /sys/config/db-cred.inc.php'; /* * Define constants for config info */ foreach ( $C as $name => $val ) { define($name, $val); } /* * Create a lookup array for form actions */ $actions = array( 'event_edit' => array( 'object' => 'Calendar', 'method' => 'processForm', 'header' => 'Location: / /' ), 'user_login' => array( 'object' => 'Admin', 'method' => 'processLoginForm', 'header' => 'Location: / /' ) ); /* * Make sure the anti-CSRF token was passed and that the * requested action exists in the lookup array */ if ( $_POST['token']==$_SESSION['token'] && isset($actions[$_POST['action']]) ) { $use_array = $actions[$_POST['action']]; $obj = new $use_array['object']($dbo); if ( TRUE === $msg=$obj->$use_array['method']() ) { header($use_array['header']); exit; } else { // If an error occured, output it and end execution die ( $msg ); CHAPTER 6 ■ PASSWORD PROTECTION SENSITIVE ACTIONS AND AREAS 215 } } else { // Redirect to the main index if the token/action is invalid header("Location: / /"); exit; } function __autoload($class_name) { $filename = ' / / /sys/class/class.' . strtolower($class_name) . '.inc.php'; if ( file_exists($filename) ) { include_once $filename; } } ?> Now you can officially test a login. Because no checks for a login are in place yet, simply add a conditional comment in index.php to show login or logout status by inserting the following bold line into the file: <?php /* * Include necessary files */ include_once ' /sys/core/init.inc.php'; /* * Load the calendar */ $cal = new Calendar($dbo, "2010-01-01 12:00:00"); /* * Set up the page title and CSS files */ $page_title = "Events Calendar"; $css_files = array('style.css', 'admin.css'); /* * Include the header */ include_once 'assets/common/header.inc.php'; ?> <div id="content"> CHAPTER 6 ■ PASSWORD PROTECTION SENSITIVE ACTIONS AND AREAS 216 <?php /* * Display the calendar HTML */ echo $cal->buildCalendar(); ?> </div><! end #content > <p> <?php echo isset($_SESSION['user']) ? "Logged In!" : "Logged Out!"; ?> </p> <?php /* * Include the footer */ include_once 'assets/common/footer.inc.php'; ?> Now save this file and navigate to http://localhost/ to see the “Logged Out!” message below the calendar (see Figure 6-4). CHAPTER 6 ■ PASSWORD PROTECTION SENSITIVE ACTIONS AND AREAS 217 Figure 6-4. Before the user logs in, the “Logged Out!” message appears below the calendar Next, navigate to http://localhost/login.php and enter the username testuser with the password, admin (see Figure 6-5). Figure 6-5. The login form with the username and password information entered CHAPTER 6 ■ PASSWORD PROTECTION SENSITIVE ACTIONS AND AREAS 218 After clicking the Log In button, you’ll be redirected back to the calendar; however, now the message below the calendar will read “Logged In!” (see Figure 6-6). Figure 6-6. After the user logs in, the “Logged In!” message appears below the calendar Allowing the User to Log Out Next, you need to add a method that allows the user to log out. You will do this using a form that submits information to process.inc.php. The method _adminGeneralOptions() in the Calendar class generates the form. Adding a Log Out Button to the Calendar To add a button that allows users to log out, modify _adminGeneralOptions() in the Calendar class. In addition to providing a button for adding new events, this method will now also output a form that submits the site token and an action value of user_logout to process.inc.php. Open the Calendar class and modify _adminGeneralOptions() with the following bold code: private function _adminGeneralOptions() { /* * Display admin controls CHAPTER 6 ■ PASSWORD PROTECTION SENSITIVE ACTIONS AND AREAS 219 */ return <<<ADMIN_OPTIONS <a href="admin.php" class="admin">+ Add a New Event</a> <form action="assets/inc/process.inc.php" method="post"> <div> <input type="submit" value="Log Out" class="admin" /> <input type="hidden" name="token" value="$_SESSION[token]" /> <input type="hidden" name="action" value="user_logout" /> </div> </form> ADMIN_OPTIONS; } Now save the changes and refresh http://localhost/ in your browser to see the new button (see Figure 6-7). Figure 6-7. The Log Out button as it appears after you modify the Calendar class CHAPTER 6 ■ PASSWORD PROTECTION SENSITIVE ACTIONS AND AREAS 220 Creating a Method to Process the Logout To process the logout, a new public method called processLogout() needs to be added to the Admin class. This method does a quick check to make sure the proper action, user_logout, was supplied, and then uses session_destroy() to remove the user data array by destroying the current session entirely. You add this method to the Admin class by inserting the following bold code: <?php class Admin extends DB_Connect { private $_saltLength = 7; public function __construct($db=NULL, $saltLength=NULL) { } public function processLoginForm() { } /** * Logs out the user * * @return mixed TRUE on success or messsage on failure */ public function processLogout() { /* * Fails if the proper action was not submitted */ if ( $_POST['action']!='user_logout' ) { return "Invalid action supplied for processLogout."; } /* * Removes the user array from the current session */ session_destroy(); return TRUE; } private function _getSaltedHash($string, $salt=NULL) { } } ?> . preceding code, click the php- jquery_ example database, and then the users table. Select the Browse tab to view the user info in the table (see Figure 6-3 ). Figure 6-3 . The test user data after. hash, navigate to http://localhost/phpmyadmin, and then click the SQL tab. Execute the following query to insert a test user into the table: INSERT INTO `php- jquery_ example`.`users` (`user_name`,. test .php. Add the following bold code to test .php to generate a salted hash of your test user’s password: < ?php // Include necessary files include_once ' /sys/core/init.inc .php& apos;;