title: How to use recaptcha API
body: <p>I want to use recaptcha in Yii, here is the way to make component,
  <a href="http://www.yiiframework.com/wiki/165/understanding-autoloading-helper-classes-and-helper-functions/" rel="nofollow noreferrer">http://www.yiiframework.com/wiki/165/understanding-autoloading-helper-classes-and-helper-functions/</a></p>
  
  <p>But now problem is that recaptchalib.php is the file required to do the work and this is the file having class and constants and functions and these are interrelated. </p>
  
  <p>I want to know that now how I can make it component and use in Yii as it is neither functions only nor only class. Is there a better way to do this?</p>
  
  <p>Here is the code for recaptchalib.php</p>
  
  <pre><code>          &lt;?php
          /*
           * This is a PHP library that handles calling reCAPTCHA.
           *    - Documentation and latest version
           *          http://recaptcha.net/plugins/php/
           *    - Get a reCAPTCHA API Key
           *          https://www.google.com/recaptcha/admin/create
           *    - Discussion group
           *          http://groups.google.com/group/recaptcha
           *
           * Copyright (c) 2007 reCAPTCHA -- http://recaptcha.net
           * AUTHORS:
           *   Mike Crawford
           *   Ben Maurer
           *
           * 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:
           *
           * The above copyright notice and this permission notice shall be included in
           * all copies or substantial portions of the Software.
           *
           * 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.
           */
  
          /**
           * The reCAPTCHA server URL's
           */
          define("RECAPTCHA_API_SERVER", "http://www.google.com/recaptcha/api");
          define("RECAPTCHA_API_SECURE_SERVER", "https://www.google.com/recaptcha/api");
          define("RECAPTCHA_VERIFY_SERVER", "www.google.com");
  
          /**
           * Encodes the given data into a query string format
           * @param $data - array of string elements to be encoded
           * @return string - encoded request
           */
          function _recaptcha_qsencode ($data) {
                  $req = "";
                  foreach ( $data as $key =&gt; $value )
                          $req .= $key . '=' . urlencode( stripslashes($value) ) . '&amp;';
  
                  // Cut the last '&amp;'
                  $req=substr($req,0,strlen($req)-1);
                  return $req;
          }
  
  
  
          /**
           * Submits an HTTP POST to a reCAPTCHA server
           * @param string $host
           * @param string $path
           * @param array $data
           * @param int port
           * @return array response
           */
          function _recaptcha_http_post($host, $path, $data, $port = 80) {
  
                  $req = _recaptcha_qsencode ($data);
  
                  $http_request  = "POST $path HTTP/1.0\r\n";
                  $http_request .= "Host: $host\r\n";
                  $http_request .= "Content-Type: application/x-www-form-urlencoded;\r\n";
                  $http_request .= "Content-Length: " . strlen($req) . "\r\n";
                  $http_request .= "User-Agent: reCAPTCHA/PHP\r\n";
                  $http_request .= "\r\n";
                  $http_request .= $req;
  
                  $response = '';
                  if( false == ( $fs = @fsockopen($host, $port, $errno, $errstr, 10) ) ) {
                          die ('Could not open socket');
                  }
  
                  fwrite($fs, $http_request);
  
                  while ( !feof($fs) )
                          $response .= fgets($fs, 1160); // One TCP-IP packet
                  fclose($fs);
                  $response = explode("\r\n\r\n", $response, 2);
  
                  return $response;
          }
  
  
  
          /**
           * Gets the challenge HTML (javascript and non-javascript version).
           * This is called from the browser, and the resulting reCAPTCHA HTML widget
           * is embedded within the HTML form it was called from.
           * @param string $pubkey A public key for reCAPTCHA
           * @param string $error The error given by reCAPTCHA (optional, default is null)
           * @param boolean $use_ssl Should the request be made over ssl? (optional, default is false)
  
           * @return string - The HTML to be embedded in the user's form.
           */
          function recaptcha_get_html ($pubkey, $error = null, $use_ssl = false)
          {
                  if ($pubkey == null || $pubkey == '') {
                          die ("To use reCAPTCHA you must get an API key from &lt;a href='https://www.google.com/recaptcha/admin/create'&gt;https://www.google.com/recaptcha/admin/create&lt;/a&gt;");
                  }
  
                  if ($use_ssl) {
                          $server = RECAPTCHA_API_SECURE_SERVER;
                  } else {
                          $server = RECAPTCHA_API_SERVER;
                  }
  
                  $errorpart = "";
                  if ($error) {
                     $errorpart = "&amp;amp;error=" . $error;
                  }
                  return '&lt;script type="text/javascript" src="'. $server . '/challenge?k=' . $pubkey . $errorpart . '"&gt;&lt;/script&gt;
  
                  &lt;noscript&gt;
                          &lt;iframe src="'. $server . '/noscript?k=' . $pubkey . $errorpart . '" height="300" width="500" frameborder="0"&gt;&lt;/iframe&gt;&lt;br/&gt;
                          &lt;textarea name="recaptcha_challenge_field" rows="3" cols="40"&gt;&lt;/textarea&gt;
                          &lt;input type="hidden" name="recaptcha_response_field" value="manual_challenge"/&gt;
                  &lt;/noscript&gt;';
          }
  
  
  
  
          /**
           * A ReCaptchaResponse is returned from recaptcha_check_answer()
           */
          class ReCaptchaResponse {
                  var $is_valid;
                  var $error;
          }
  
  
          /**
            * Calls an HTTP POST function to verify if the user's guess was correct
            * @param string $privkey
            * @param string $remoteip
            * @param string $challenge
            * @param string $response
            * @param array $extra_params an array of extra variables to post to the server
            * @return ReCaptchaResponse
            */
          function recaptcha_check_answer ($privkey, $remoteip, $challenge, $response, $extra_params = array())
          {
                  if ($privkey == null || $privkey == '') {
                          die ("To use reCAPTCHA you must get an API key from &lt;a href='https://www.google.com/recaptcha/admin/create'&gt;https://www.google.com/recaptcha/admin/create&lt;/a&gt;");
                  }
  
                  if ($remoteip == null || $remoteip == '') {
                          die ("For security reasons, you must pass the remote ip to reCAPTCHA");
                  }
  
  
  
                  //discard spam submissions
                  if ($challenge == null || strlen($challenge) == 0 || $response == null || strlen($response) == 0) {
                          $recaptcha_response = new ReCaptchaResponse();
                          $recaptcha_response-&gt;is_valid = false;
                          $recaptcha_response-&gt;error = 'incorrect-captcha-sol';
                          return $recaptcha_response;
                  }
  
                  $response = _recaptcha_http_post (RECAPTCHA_VERIFY_SERVER, "/recaptcha/api/verify",
                                                    array (
                                                           'privatekey' =&gt; $privkey,
                                                           'remoteip' =&gt; $remoteip,
                                                           'challenge' =&gt; $challenge,
                                                           'response' =&gt; $response
                                                           ) + $extra_params
                                                    );
  
                  $answers = explode ("\n", $response [1]);
                  $recaptcha_response = new ReCaptchaResponse();
  
                  if (trim ($answers [0]) == 'true') {
                          $recaptcha_response-&gt;is_valid = true;
                  }
                  else {
                          $recaptcha_response-&gt;is_valid = false;
                          $recaptcha_response-&gt;error = $answers [1];
                  }
                  return $recaptcha_response;
  
          }
  
          /**
           * gets a URL where the user can sign up for reCAPTCHA. If your application
           * has a configuration page where you enter a key, you should provide a link
           * using this function.
           * @param string $domain The domain where the page is hosted
           * @param string $appname The name of your application
           */
          function recaptcha_get_signup_url ($domain = null, $appname = null) {
                  return "https://www.google.com/recaptcha/admin/create?" .  _recaptcha_qsencode (array ('domains' =&gt; $domain, 'app' =&gt; $appname));
          }
  
          function _recaptcha_aes_pad($val) {
                  $block_size = 16;
                  $numpad = $block_size - (strlen ($val) % $block_size);
                  return str_pad($val, strlen ($val) + $numpad, chr($numpad));
          }
  
          /* Mailhide related code */
  
          function _recaptcha_aes_encrypt($val,$ky) {
                  if (! function_exists ("mcrypt_encrypt")) {
                          die ("To use reCAPTCHA Mailhide, you need to have the mcrypt php module installed.");
                  }
                  $mode=MCRYPT_MODE_CBC;   
                  $enc=MCRYPT_RIJNDAEL_128;
                  $val=_recaptcha_aes_pad($val);
                  return mcrypt_encrypt($enc, $ky, $val, $mode, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0");
          }
  
  
          function _recaptcha_mailhide_urlbase64 ($x) {
                  return strtr(base64_encode ($x), '+/', '-_');
          }
  
          /* gets the reCAPTCHA Mailhide url for a given email, public key and private key */
          function recaptcha_mailhide_url($pubkey, $privkey, $email) {
                  if ($pubkey == '' || $pubkey == null || $privkey == "" || $privkey == null) {
                          die ("To use reCAPTCHA Mailhide, you have to sign up for a public and private key, " .
                               "you can do so at &lt;a href='http://www.google.com/recaptcha/mailhide/apikey'&gt;http://www.google.com/recaptcha/mailhide/apikey&lt;/a&gt;");
                  }
  
  
                  $ky = pack('H*', $privkey);
                  $cryptmail = _recaptcha_aes_encrypt ($email, $ky);
  
                  return "http://www.google.com/recaptcha/mailhide/d?k=" . $pubkey . "&amp;c=" . _recaptcha_mailhide_urlbase64 ($cryptmail);
          }
  
          /**
           * gets the parts of the email to expose to the user.
           * eg, given johndoe@example,com return ["john", "example.com"].
           * the email is then displayed as john...@example.com
           */
          function _recaptcha_mailhide_email_parts ($email) {
                  $arr = preg_split("/@/", $email );
  
                  if (strlen ($arr[0]) &lt;= 4) {
                          $arr[0] = substr ($arr[0], 0, 1);
                  } else if (strlen ($arr[0]) &lt;= 6) {
                          $arr[0] = substr ($arr[0], 0, 3);
                  } else {
                          $arr[0] = substr ($arr[0], 0, 4);
                  }
                  return $arr;
          }
  
          /**
           * Gets html to display an email address given a public an private key.
           * to get a key, go to:
           *
           * http://www.google.com/recaptcha/mailhide/apikey
           */
          function recaptcha_mailhide_html($pubkey, $privkey, $email) {
                  $emailparts = _recaptcha_mailhide_email_parts ($email);
                  $url = recaptcha_mailhide_url ($pubkey, $privkey, $email);
  
                  return htmlentities($emailparts[0]) . "&lt;a href='" . htmlentities ($url) .
                          "' onclick=\"window.open('" . htmlentities ($url) . "', '', 'toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=500,height=300'); return false;\" title=\"Reveal this e-mail address\"&gt;...&lt;/a&gt;@" . htmlentities ($emailparts [1]);
  
          }
  
  
          ?&gt;
  </code></pre>