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<?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 => $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 = "&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]);

}

?>