<?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)
 * @param string $prefix
 * @return string - The HTML to be embedded in the user's form.
 */
function recaptcha_get_html($pubkey, $error = null, $use_ssl = false, $prefix = 'recaptcha'){
	if($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="' . $prefix . '_challenge_field" rows="3" cols="40"></textarea>
          <input type="hidden" name="' . $prefix . '_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 = []){

	if(DEVELOPER_MODE){
		$recaptcha_response = new ReCaptchaResponse();
		$recaptcha_response->is_valid = true;
		return $recaptcha_response;
	}

	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", ['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 $appname The name of your application
 * @return string
 */
function recaptcha_get_signup_url($domain = null, $appname = null){
	return "https://www.google.com/recaptcha/admin/create?" . _recaptcha_qsencode(['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]);

}
