<?php
/*
 * This is a PHP library that handles calling reCAPTCHA.
 *    - Documentation and latest version
 *          http://recaptcha.net/plugins/php/
 *    - Get a reCAPTCHA API Key
 *          http://recaptcha.net/api/getkey
 *    - 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.
 */

/**
	* Encodes the given data into a query string format
	* @param $data - array of string elements to be encoded
	* @return string - encoded request
	*/
function fst__recaptcha_qsencode ($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 $data
	* @param int port
	* @return array response
	*/
function fst__recaptcha_http_post($host, $path, $data, $port = 80) {

	$req = fst__recaptcha_qsencode ($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 fst_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='http://recaptcha.net/api/getkey'>http://recaptcha.net/api/getkey</a>");
	}
	
	if ($use_ssl) {
		$server = fst_RECAPTCHA_API_SECURE_SERVER;
	} else {
		$server = fst_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 fst_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 $extra_params an array of extra variables to post to the server
	* @return ReCaptchaResponse
	*/
function fst_recaptcha_check_answer ($privkey, $remoteip, $challenge, $response, $extra_params = array())
{
	if ($privkey == null || $privkey == '') {
		die ("To use reCAPTCHA you must get an API key from <a href='http://recaptcha.net/api/getkey'>http://recaptcha.net/api/getkey</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 fst_ReCaptchaResponse();
		$recaptcha_response->is_valid = false;
		$recaptcha_response->error = 'incorrect-captcha-sol';
		return $recaptcha_response;
	}

	$response = fst__recaptcha_http_post (fst_RECAPTCHA_VERIFY_SERVER, "/verify",
		array (
				'privatekey' => $privkey,
				'remoteip' => $remoteip,
				'challenge' => $challenge,
				'response' => $response
				) + $extra_params
			);

	$answers = explode ("\n", $response [1]);
	$recaptcha_response = new fst_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 $appname The name of your application
	*/
function fst_recaptcha_get_signup_url ($domain = null, $appname = null) {
	return "http://recaptcha.net/api/getkey?" .  _recaptcha_qsencode (array ('domain' => $domain, 'app' => $appname));
}

function fst__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 fst__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;
	$val=fst__recaptcha_aes_pad($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 fst__recaptcha_mailhide_urlbase64 ($x) {
	return strtr(base64_encode ($x), '+/', '-_');
}

/* gets the reCAPTCHA Mailhide url for a given email, public key and private key */
function fst_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://mailhide.recaptcha.net/apikey'>http://mailhide.recaptcha.net/apikey</a>");
	}
	

	$ky = pack('H*', $privkey);
	$cryptmail = fst__recaptcha_aes_encrypt ($email, $ky);
	
	return "http://mailhide.recaptcha.net/d?k=" . $pubkey . "&c=" . fst__recaptcha_mailhide_urlbase64 ($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 fst__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://mailhide.recaptcha.net/apikey
	*/
function fst_recaptcha_mailhide_html($pubkey, $privkey, $email) {
	$emailparts = fst__recaptcha_mailhide_email_parts ($email);
	$url = fst_recaptcha_mailhide_url ($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]);

}