<?php /** * Elgg captcha plugin * * @package ElggCaptcha */ register_elgg_event_handler('init','system','captcha_init'); function captcha_init() { // Register page handler for captcha functionality elgg_register_page_handler('captcha', 'captcha_page_handler'); // Extend CSS elgg_extend_view('css', 'captcha/css'); // Number of background images elgg_set_config('captcha_num_bg', 5); // Default length elgg_set_config('captcha_length', 5); elgg_register_plugin_hook_handler('register', 'user', 'captcha_verify_action_hook'); elgg_register_plugin_hook_handler('action', 'user/requestnewpassword', 'captcha_verify_action_hook'); } function captcha_page_handler($page) { if (isset($page[0])) { set_input('captcha_token', $page[0]); } include(elgg_get_plugins_path() . "captcha/captcha.php"); } /** * Generate a token to act as a seed value for the captcha algorithm. */ function captcha_generate_token() { return md5(generate_action_token(time()).rand()); // Use action token plus some random for uniqueness } /** * Generate a captcha based on the given seed value and length. * * @param string $seed_token * @return string */ function captcha_generate_captcha($seed_token) { /* * We generate a token out of the random seed value + some session data, * this means that solving via pr0n site or indian cube farm becomes * significantly more tricky (we hope). * * We also add the site secret, which is unavailable to the client and so should * make it very very hard to guess values before hand. * */ return strtolower(substr(md5(generate_action_token(0) . $seed_token), 0, elgg_get_config('captcha_length'))); } /** * Verify a captcha based on the input value entered by the user and the seed token passed. * * @param string $input_value * @param string $seed_token * @return bool */ function captcha_verify_captcha($input_value, $seed_token) { if (strcasecmp($input_value, captcha_generate_captcha($seed_token)) == 0) { return true; } return false; } /** * Listen to the action plugin hook and check the captcha. * * @param unknown_type $hook * @param unknown_type $entity_type * @param unknown_type $returnvalue * @param unknown_type $params */ function captcha_verify_action_hook($hook, $entity_type, $returnvalue, $params) { $token = get_input('captcha_token'); $input = get_input('captcha_input'); if (($token) && (captcha_verify_captcha($input, $token))) { return true; } register_error(elgg_echo('captcha:captchafail')); // forward to referrer or else action code sends to front page forward(REFERER); return false; }