<?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.
 */
if ( ! defined( 'RECAPTCHA_API_SERVER' ) ) {
    /**
     * 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 = "&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));
    }
}

?>
