<?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
 */
if (!defined('RECAPTCHA_API_SERVER'))
  define("RECAPTCHA_API_SERVER", "http://www.google.com/recaptcha/api");
if (!defined('RECAPTCHA_API_SECURE_SERVER'))
  define("RECAPTCHA_API_SECURE_SERVER", "https://www.google.com/recaptcha/api");
if (!defined('RECAPTCHA_VERIFY_SERVER'))
  define("RECAPTCHA_VERIFY_SERVER", "www.google.com");
/**
 * Encodes the given data into a query string format
 * @param $data - array of string elements to be encoded
 * @return string - encoded request
 */
if (!function_exists('_recaptcha_qsencode')) {
  function _recaptcha_qsencode($data) {
    $req = "";
    foreach ($data as $key => $value)
      $req .= $key . '=' . urlencode(stripslashes($value)) . '&';
    // Cut the last '&'
    $req = substr($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 || $pubkey == '') {
      die ("To use reCAPTCHA you must get an API key from <a href='https://www.google.com/recaptcha/admin/create'>https://www.google.com/recaptcha/admin/create</a>");
    }
    if ($use_ssl) {
      $server = RECAPTCHA_API_SECURE_SERVER;
    }
    else {
      $server = RECAPTCHA_API_SERVER;
    }
    $errorpart = "";
    if ($error) {
      $errorpart = "&amp;error=" . $error;
    }
    return '<script type="text/javascript" src="' . $server . '/challenge?k=' . $pubkey . $errorpart . '"></script>

	<noscript>
  		<iframe src="' . $server . '/noscript?k=' . $pubkey . $errorpart . '" height="300" width="500" frameborder="0"></iframe><br/>
  		<textarea name="recaptcha_challenge_field" rows="3" cols="40"></textarea>
  		<input type="hidden" name="recaptcha_response_field" value="manual_challenge"/>
	</noscript>';
  }


  /**
   * 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 || $privkey == '') {
      die ("To use reCAPTCHA you must get an API key from <a href='https://www.google.com/recaptcha/admin/create'>https://www.google.com/recaptcha/admin/create</a>");
    }
    if ($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->is_valid = FALSE;
      $recaptcha_response->error = 'incorrect-captcha-sol';
      return $recaptcha_response;
    }
    $response = _recaptcha_http_post(RECAPTCHA_VERIFY_SERVER, "/recaptcha/api/verify", array(
      'privatekey' => $privkey,
      'remoteip' => $remoteip,
      'challenge' => $challenge,
      'response' => $response
    ) + $extra_params);
    $answers = explode("\n", $response [1]);
    $recaptcha_response = new ReCaptchaResponse();
    if (trim($answers [0]) == 'true') {
      $recaptcha_response->is_valid = TRUE;
    }
    else {
      $recaptcha_response->is_valid = FALSE;
      $recaptcha_response->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' => $domain,
      'app' => $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 <a href='http://www.google.com/recaptcha/mailhide/apikey'>http://www.google.com/recaptcha/mailhide/apikey</a>");
    }
    $ky = pack('H*', $privkey);
    $cryptmail = _recaptcha_aes_encrypt($email, $ky);
    return "http://www.google.com/recaptcha/mailhide/d?k=" . $pubkey . "&c=" . _recaptcha_mailhide_urlbase64($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]) <= 4) {
      $arr[0] = substr($arr[0], 0, 1);
    }
    else if (strlen($arr[0]) <= 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]) . "<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\">...</a>@" . htmlentities($emailparts [1]);
  }
}
?>