recaptchalib.php

<?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 );
	
	$response = '';
	
	$url = 'http://' . $host . ':' . $post . $path;
	$params = array (
			'http' => array (
					'method' => 'POST',
					'header' => "Content-Type: application/x-www-form-urlencoded;\r\n",
					'content' => $req 
			) 
	);
	$context = stream_context_create ( $params );
	$response = "\r\n\r\n" . @file_get_contents ( $url, false, $context ); // simulate
	                                                                    // answer
	                                                                    // of
	                                                                    // fsockopen
	
	$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] );
}

?>