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  *          https://www.google.com/recaptcha/admin/create
   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://www.google.com/recaptcha/api");
  39 define("RECAPTCHA_API_SECURE_SERVER", "https://www.google.com/recaptcha/api");
  40 define("RECAPTCHA_VERIFY_SERVER", "www.google.com");
  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) {
  68
  69         $req = _recaptcha_qsencode ($data);
  70
  71         $http_request  = "POST $path HTTP/1.0\r\n";
  72         $http_request .= "Host: $host\r\n";
  73         $http_request .= "Content-Type: application/x-www-form-urlencoded;\r\n";
  74         $http_request .= "Content-Length: " . strlen($req) . "\r\n";
  75         $http_request .= "User-Agent: reCAPTCHA/PHP\r\n";
  76         $http_request .= "\r\n";
  77         $http_request .= $req;
  78
  79         $response = '';
  80         if( false == ( $fs = @fsockopen($host, $port, $errno, $errstr, 10) ) ) {
  81                 die ('Could not open socket');
  82         }
  83
  84         fwrite($fs, $http_request);
  85
  86         while ( !feof($fs) )
  87                 $response .= fgets($fs, 1160); // One TCP-IP packet
  88         fclose($fs);
  89         $response = explode("\r\n\r\n", $response, 2);
  90
  91         return $response;
  92 }
  93
  94
  95
  96 /**
  97  * Gets the challenge HTML (javascript and non-javascript version).
  98  * This is called from the browser, and the resulting reCAPTCHA HTML widget
  99  * is embedded within the HTML form it was called from.
 100  * @param string $pubkey A public key for reCAPTCHA
 101  * @param string $error The error given by reCAPTCHA (optional, default is null)
 102  * @param boolean $use_ssl Should the request be made over ssl? (optional, default is false)
 103
 104  * @return string - The HTML to be embedded in the user's form.
 105  */
 106 function recaptcha_get_html ($pubkey, $error = null, $use_ssl = false)
 107 {
 108         if ($pubkey == null || $pubkey == '') {
 109                 die ("To use reCAPTCHA you must get an API key from <a href='https://www.google.com/recaptcha/admin/create'>https://www.google.com/recaptcha/admin/create</a>");
 110         }
 111
 112         if ($use_ssl) {
 113                 $server = RECAPTCHA_API_SECURE_SERVER;
 114         } else {
 115                 $server = RECAPTCHA_API_SERVER;
 116         }
 117
 118         $errorpart = "";
 119         if ($error) {
 120            $errorpart = "&amp;error=" . $error;
 121         }
 122         return '<script type="text/javascript" src="'. $server . '/challenge?k=' . $pubkey . $errorpart . '"></script>
 123
 124         <noscript>
 125                 <iframe src="'. $server . '/noscript?k=' . $pubkey . $errorpart . '" height="300" width="500" frameborder="0"></iframe><br/>
 126                 <textarea name="recaptcha_challenge_field" rows="3" cols="40"></textarea>
 127                 <input type="hidden" name="recaptcha_response_field" value="manual_challenge"/>
 128         </noscript>';
 129 }
 130
 131
 132
 133
 134 /**
 135  * A ReCaptchaResponse is returned from recaptcha_check_answer()
 136  */
 137 class ReCaptchaResponse {
 138         var $is_valid;
 139         var $error;
 140 }
 141
 142
 143 /**
 144   * Calls an HTTP POST function to verify if the user's guess was correct
 145   * @param string $privkey
 146   * @param string $remoteip
 147   * @param string $challenge
 148   * @param string $response
 149   * @param array $extra_params an array of extra variables to post to the server
 150   * @return ReCaptchaResponse
 151   */
 152 function recaptcha_check_answer ($privkey, $remoteip, $challenge, $response, $extra_params = array())
 153 {
 154         if ($privkey == null || $privkey == '') {
 155                 die ("To use reCAPTCHA you must get an API key from <a href='https://www.google.com/recaptcha/admin/create'>https://www.google.com/recaptcha/admin/create</a>");
 156         }
 157
 158         if ($remoteip == null || $remoteip == '') {
 159                 die ("For security reasons, you must pass the remote ip to reCAPTCHA");
 160         }
 161
 162
 163
 164         //discard spam submissions
 165         if ($challenge == null || strlen($challenge) == 0 || $response == null || strlen($response) == 0) {
 166                 $recaptcha_response = new ReCaptchaResponse();
 167                 $recaptcha_response->is_valid = false;
 168                 $recaptcha_response->error = 'incorrect-captcha-sol';
 169                 return $recaptcha_response;
 170         }
 171
 172         $response = _recaptcha_http_post (RECAPTCHA_VERIFY_SERVER, "/recaptcha/api/verify",
 173                                           array (
 174                                                  'privatekey' => $privkey,
 175                                                  'remoteip' => $remoteip,
 176                                                  'challenge' => $challenge,
 177                                                  'response' => $response
 178                                                  ) + $extra_params
 179                                           );
 180
 181         $answers = explode ("\n", $response [1]);
 182         $recaptcha_response = new ReCaptchaResponse();
 183
 184         if (trim ($answers [0]) == 'true') {
 185                 $recaptcha_response->is_valid = true;
 186         }
 187         else {
 188                 $recaptcha_response->is_valid = false;
 189                 $recaptcha_response->error = $answers [1];
 190         }
 191         return $recaptcha_response;
 192
 193 }
 194
 195 /**
 196  * gets a URL where the user can sign up for reCAPTCHA. If your application
 197  * has a configuration page where you enter a key, you should provide a link
 198  * using this function.
 199  * @param string $domain The domain where the page is hosted
 200  * @param string $appname The name of your application
 201  */
 202 function recaptcha_get_signup_url ($domain = null, $appname = null) {
 203         return "https://www.google.com/recaptcha/admin/create?" .  _recaptcha_qsencode (array ('domains' => $domain, 'app' => $appname));
 204 }
 205
 206 function _recaptcha_aes_pad($val) {
 207         $block_size = 16;
 208         $numpad = $block_size - (strlen ($val) % $block_size);
 209         return str_pad($val, strlen ($val) + $numpad, chr($numpad));
 210 }
 211
 212 /* Mailhide related code */
 213
 214 function _recaptcha_aes_encrypt($val,$ky) {
 215         if (! function_exists ("mcrypt_encrypt")) {
 216                 die ("To use reCAPTCHA Mailhide, you need to have the mcrypt php module installed.");
 217         }
 218         $mode=MCRYPT_MODE_CBC;
 219         $enc=MCRYPT_RIJNDAEL_128;
 220         $val=_recaptcha_aes_pad($val);
 221         return mcrypt_encrypt($enc, $ky, $val, $mode, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0");
 222 }
 223
 224
 225 function _recaptcha_mailhide_urlbase64 ($x) {
 226         return strtr(base64_encode ($x), '+/', '-_');
 227 }
 228
 229 /* gets the reCAPTCHA Mailhide url for a given email, public key and private key */
 230 function recaptcha_mailhide_url($pubkey, $privkey, $email) {
 231         if ($pubkey == '' || $pubkey == null || $privkey == "" || $privkey == null) {
 232                 die ("To use reCAPTCHA Mailhide, you have to sign up for a public and private key, " .
 233                      "you can do so at <a href='http://www.google.com/recaptcha/mailhide/apikey'>http://www.google.com/recaptcha/mailhide/apikey</a>");
 234         }
 235
 236
 237         $ky = pack('H*', $privkey);
 238         $cryptmail = _recaptcha_aes_encrypt ($email, $ky);
 239
 240         return "http://www.google.com/recaptcha/mailhide/d?k=" . $pubkey . "&c=" . _recaptcha_mailhide_urlbase64 ($cryptmail);
 241 }
 242
 243 /**
 244  * gets the parts of the email to expose to the user.
 245  * eg, given johndoe@example,com return ["john", "example.com"].
 246  * the email is then displayed as john...@example.com
 247  */
 248 function _recaptcha_mailhide_email_parts ($email) {
 249         $arr = preg_split("/@/", $email );
 250
 251         if (strlen ($arr[0]) <= 4) {
 252                 $arr[0] = substr ($arr[0], 0, 1);
 253         } else if (strlen ($arr[0]) <= 6) {
 254                 $arr[0] = substr ($arr[0], 0, 3);
 255         } else {
 256                 $arr[0] = substr ($arr[0], 0, 4);
 257         }
 258         return $arr;
 259 }
 260
 261 /**
 262  * Gets html to display an email address given a public an private key.
 263  * to get a key, go to:
 264  *
 265  * http://www.google.com/recaptcha/mailhide/apikey
 266  */
 267 function recaptcha_mailhide_html($pubkey, $privkey, $email) {
 268         $emailparts = _recaptcha_mailhide_email_parts ($email);
 269         $url = recaptcha_mailhide_url ($pubkey, $privkey, $email);
 270
 271         return htmlentities($emailparts[0]) . "<a href='" . htmlentities ($url) .
 272                 "' onclick=\"window.open('" . htmlentities ($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]);
 273
 274 }
 275
 276
 277 ?>