lib/recaptchalib.php

   1 <?php
   2 /*
   3  * This is a PHP library that handles calling reCAPTCHA.
   4  *    - Documentation and latest version
   5  *          http://recaptcha.net/plugins/php/
   6  *    - Get a reCAPTCHA API Key
   7  *          http://recaptcha.net/api/getkey
   8  *    - Discussion group
   9  *          http://groups.google.com/group/recaptcha
  10  *
  11  * Copyright (c) 2007 reCAPTCHA -- http://recaptcha.net
  12  * AUTHORS:
  13  *   Mike Crawford
  14  *   Ben Maurer
  15  *
  16  * Permission is hereby granted, free of charge, to any person obtaining a copy
  17  * of this software and associated documentation files (the "Software"), to deal
  18  * in the Software without restriction, including without limitation the rights
  19  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  20  * copies of the Software, and to permit persons to whom the Software is
  21  * furnished to do so, subject to the following conditions:
  22  *
  23  * The above copyright notice and this permission notice shall be included in
  24  * all copies or substantial portions of the Software.
  25  *
  26  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  27  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  28  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  29  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  30  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  31  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  32  * THE SOFTWARE.
  33  */
  34
  35 /**
  36  * The reCAPTCHA server URL's
  37  */
  38 define("RECAPTCHA_API_SERVER", "http://api.recaptcha.net");
  39 define("RECAPTCHA_API_SECURE_SERVER", "https://api-secure.recaptcha.net");
  40 define("RECAPTCHA_VERIFY_SERVER", "api-verify.recaptcha.net");
  41
  42 /**
  43  * Encodes the given data into a query string format
  44  * @param $data - array of string elements to be encoded
  45  * @return string - encoded request
  46  */
  47 function _recaptcha_qsencode ($data) {
  48         $req = "";
  49         foreach ( $data as $key => $value )
  50                 $req .= $key . '=' . urlencode( stripslashes($value) ) . '&';
  51
  52         // Cut the last '&'
  53         $req=substr($req,0,strlen($req)-1);
  54         return $req;
  55 }
  56
  57
  58
  59 /**
  60  * Submits an HTTP POST to a reCAPTCHA server
  61  * @param string $host
  62  * @param string $path
  63  * @param array $data
  64  * @param int port
  65  * @return array response
  66  */
  67 function _recaptcha_http_post($host, $path, $data, $port = 80, $https=false) {
  68         global $CFG;
  69         $protocol = 'http';
  70         if ($https) {
  71             $protocol = 'https';
  72         }
  73
  74         require_once $CFG->libdir . '/filelib.php';
  75
  76         $req = _recaptcha_qsencode ($data);
  77
  78         $headers = array();
  79         $headers['Host'] = $host;
  80         $headers['Content-Type'] = 'application/x-www-form-urlencoded';
  81         $headers['Content-Length'] = strlen($req);
  82         $headers['User-Agent'] = 'reCAPTCHA/PHP';
  83
  84         $results = download_file_content("$protocol://" . $host . $path, $headers, $data, false, 300, 20, true);
  85
  86         if ($results) {
  87             return array(1 => $results);
  88         } else {
  89             return false;
  90         }
  91 }
  92
  93
  94
  95 /**
  96  * Gets the challenge HTML (javascript and non-javascript version).
  97  * This is called from the browser, and the resulting reCAPTCHA HTML widget
  98  * is embedded within the HTML form it was called from.
  99  * @param string $pubkey A public key for reCAPTCHA
 100  * @param string $error The error given by reCAPTCHA (optional, default is null)
 101  * @param boolean $use_ssl Should the request be made over ssl? (optional, default is false)
 102
 103  * @return string - The HTML to be embedded in the user's form.
 104  */
 105 function recaptcha_get_html ($pubkey, $error = null, $use_ssl = false) {
 106     global $CFG;
 107
 108     $recaptchatype = optional_param('recaptcha', 'image', PARAM_TEXT);
 109
 110         if ($pubkey == null || $pubkey == '') {
 111                 die ("To use reCAPTCHA you must get an API key from <a href='http://recaptcha.net/api/getkey'>http://recaptcha.net/api/getkey</a>");
 112         }
 113
 114         if ($use_ssl) {
 115                 $server = RECAPTCHA_API_SECURE_SERVER;
 116         } else {
 117                 $server = RECAPTCHA_API_SERVER;
 118         }
 119
 120         $errorpart = "";
 121         if ($error) {
 122            $errorpart = "&amp;error=" . $error;
 123         }
 124
 125     require_once $CFG->libdir . '/filelib.php';
 126     $html = download_file_content($server . '/noscript?k=' . $pubkey . $errorpart, null, null, false, 300, 20, true);
 127     preg_match('/image\?c\=([A-Za-z0-9\-\_]*)\"/', $html, $matches);
 128     $challenge_hash = $matches[1];
 129     $image_url = $server . '/image?c=' . $challenge_hash;
 130
 131     $strincorrectpleasetryagain = get_string('incorrectpleasetryagain', 'auth');
 132     $strenterthewordsabove = get_string('enterthewordsabove', 'auth');
 133     $strenterthenumbersyouhear = get_string('enterthenumbersyouhear', 'auth');
 134     $strgetanothercaptcha = get_string('getanothercaptcha', 'auth');
 135     $strgetanaudiocaptcha = get_string('getanaudiocaptcha', 'auth');
 136     $strgetanimagecaptcha = get_string('getanimagecaptcha', 'auth');
 137
 138     $return = '<script type="text/javascript" src="'. $server . '/challenge?k=' . $pubkey . $errorpart . '"></script>
 139         <noscript>
 140         <div id="recaptcha_widget_noscript">
 141         <div id="recaptcha_image_noscript"><img src="' . $image_url . '" alt="reCAPTCHA"/></div>';
 142
 143     if ($error == 'incorrect-captcha-sol') {
 144         $return .= '<div class="recaptcha_only_if_incorrect_sol" style="color:red">' . $strincorrectpleasetryagain . '</div>';
 145     }
 146
 147     if ($recaptchatype == 'image') {
 148         $return .= '<span class="recaptcha_only_if_image">' . $strenterthewordsabove . '</span>';
 149     } elseif ($recaptchatype == 'audio') {
 150         $return .= '<span class="recaptcha_only_if_audio">' . $strenterthenumbersyouhear . '</span>';
 151     }
 152
 153     $return .= '<input type="text" id="recaptcha_response_field_noscript" name="recaptcha_response_field" />';
 154     $return .= '<input type="hidden" id="recaptcha_challenge_field_noscript" name="recaptcha_challenge_field" value="' . $challenge_hash . '" />';
 155     $return .= '<div><a href="signup.php">' . $strgetanothercaptcha . '</a></div>';
 156
 157     // Disabling audio recaptchas for now: not language-independent
 158     /*
 159     if ($recaptchatype == 'image') {
 160         $return .= '<div class="recaptcha_only_if_image"><a href="signup.php?recaptcha=audio">' . $strgetanaudiocaptcha . '</a></div>';
 161     } elseif ($recaptchatype == 'audio') {
 162         $return .= '<div class="recaptcha_only_if_audio"><a href="signup.php?recaptcha=image">' . $strgetanimagecaptcha . '</a></div>';
 163     }
 164     */
 165
 166     $return .= '
 167         </div>
 168         </noscript>';
 169
 170     return $return;
 171 }
 172
 173
 174
 175
 176 /**
 177  * A ReCaptchaResponse is returned from recaptcha_check_answer()
 178  */
 179 class ReCaptchaResponse {
 180         var $is_valid;
 181         var $error;
 182 }
 183
 184
 185 /**
 186   * Calls an HTTP POST function to verify if the user's guess was correct
 187   * @param string $privkey
 188   * @param string $remoteip
 189   * @param string $challenge
 190   * @param string $response
 191   * @return ReCaptchaResponse
 192   */
 193 function recaptcha_check_answer ($privkey, $remoteip, $challenge, $response, $https=false)
 194 {
 195         if ($privkey == null || $privkey == '') {
 196                 die ("To use reCAPTCHA you must get an API key from <a href='http://recaptcha.net/api/getkey'>http://recaptcha.net/api/getkey</a>");
 197         }
 198
 199         if ($remoteip == null || $remoteip == '') {
 200                 die ("For security reasons, you must pass the remote ip to reCAPTCHA");
 201         }
 202
 203
 204
 205         //discard spam submissions
 206         if ($challenge == null || strlen($challenge) == 0 || $response == null || strlen($response) == 0) {
 207                 $recaptcha_response = new ReCaptchaResponse();
 208                 $recaptcha_response->is_valid = false;
 209                 $recaptcha_response->error = 'incorrect-captcha-sol';
 210                 return $recaptcha_response;
 211         }
 212
 213         $response = _recaptcha_http_post (RECAPTCHA_VERIFY_SERVER, "/verify",
 214                                           array (
 215                                                  'privatekey' => $privkey,
 216                                                  'remoteip' => $remoteip,
 217                                                  'challenge' => $challenge,
 218                                                  'response' => $response
 219                                                 ),
 220                                          $https
 221                                           );
 222
 223         $answers = explode ("\n", $response [1]);
 224         $recaptcha_response = new ReCaptchaResponse();
 225
 226         if (trim ($answers [0]) == 'true') {
 227                 $recaptcha_response->is_valid = true;
 228         }
 229         else {
 230                 $recaptcha_response->is_valid = false;
 231                 $recaptcha_response->error = $answers [1];
 232         }
 233         return $recaptcha_response;
 234
 235 }
 236
 237 /**
 238  * gets a URL where the user can sign up for reCAPTCHA. If your application
 239  * has a configuration page where you enter a key, you should provide a link
 240  * using this function.
 241  * @param string $domain The domain where the page is hosted
 242  * @param string $appname The name of your application
 243  */
 244 function recaptcha_get_signup_url ($domain = null, $appname = null) {
 245         return "http://recaptcha.net/api/getkey?" .  _recaptcha_qsencode (array ('domain' => $domain, 'app' => $appname));
 246 }
 247
 248 function _recaptcha_aes_pad($val) {
 249         $block_size = 16;
 250         $numpad = $block_size - (strlen ($val) % $block_size);
 251         return str_pad($val, strlen ($val) + $numpad, chr($numpad));
 252 }
 253
 254 /* Mailhide related code */
 255
 256 function _recaptcha_aes_encrypt($val,$ky) {
 257         if (! function_exists ("mcrypt_encrypt")) {
 258                 die ("To use reCAPTCHA Mailhide, you need to have the mcrypt php module installed.");
 259         }
 260         $mode=MCRYPT_MODE_CBC;
 261         $enc=MCRYPT_RIJNDAEL_128;
 262         $val=_recaptcha_aes_pad($val);
 263         return mcrypt_encrypt($enc, $ky, $val, $mode, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0");
 264 }
 265
 266
 267 function _recaptcha_mailhide_urlbase64 ($x) {
 268         return strtr(base64_encode ($x), '+/', '-_');
 269 }
 270
 271 /* gets the reCAPTCHA Mailhide url for a given email, public key and private key */
 272 function recaptcha_mailhide_url($pubkey, $privkey, $email) {
 273         if ($pubkey == '' || $pubkey == null || $privkey == "" || $privkey == null) {
 274                 die ("To use reCAPTCHA Mailhide, you have to sign up for a public and private key, " .
 275                      "you can do so at <a href='http://mailhide.recaptcha.net/apikey'>http://mailhide.recaptcha.net/apikey</a>");
 276         }
 277
 278
 279         $ky = pack('H*', $privkey);
 280         $cryptmail = _recaptcha_aes_encrypt ($email, $ky);
 281
 282         return "http://mailhide.recaptcha.net/d?k=" . $pubkey . "&c=" . _recaptcha_mailhide_urlbase64 ($cryptmail);
 283 }
 284
 285 /**
 286  * gets the parts of the email to expose to the user.
 287  * eg, given johndoe@example,com return ["john", "example.com"].
 288  * the email is then displayed as john...@example.com
 289  */
 290 function _recaptcha_mailhide_email_parts ($email) {
 291         $arr = preg_split("/@/", $email );
 292
 293         if (strlen ($arr[0]) <= 4) {
 294                 $arr[0] = substr ($arr[0], 0, 1);
 295         } else if (strlen ($arr[0]) <= 6) {
 296                 $arr[0] = substr ($arr[0], 0, 3);
 297         } else {
 298                 $arr[0] = substr ($arr[0], 0, 4);
 299         }
 300         return $arr;
 301 }
 302
 303 /**
 304  * Gets html to display an email address given a public an private key.
 305  * to get a key, go to:
 306  *
 307  * http://mailhide.recaptcha.net/apikey
 308  */
 309 function recaptcha_mailhide_html($pubkey, $privkey, $email) {
 310         $emailparts = _recaptcha_mailhide_email_parts ($email);
 311         $url = recaptcha_mailhide_url ($pubkey, $privkey, $email);
 312
 313         return htmlentities($emailparts[0]) . "<a href='" . htmlentities ($url) .
 314                 "' onclick=\"window.open('" . htmlentities ($url) . "', '', 'toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=500,height=300'); return false;\" title=\"Reveal this e-mail address\">...</a>@" . htmlentities ($emailparts [1]);
 315
 316 }
 317
 318
 319 ?>