<?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 = "&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 {
        public $is_valid;
        public $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 );
	} elseif ( 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] );

}
