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+<?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.
+ */
+
+/**
+ * The reCAPTCHA server URL's
+ */
+define("RECAPTCHA_API_SERVER", "http://api.recaptcha.net");
+define("RECAPTCHA_API_SECURE_SERVER", "https://api-secure.recaptcha.net");
+define("RECAPTCHA_VERIFY_SERVER", "api-verify.recaptcha.net");
+
+/**
+ * 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 || $pubkey == '') {
+                die ("To use reCAPTCHA you must get an API key from <a href='http://recaptcha.net/api/getkey'>http://recaptcha.net/api/getkey</a>");
+        }
+        
+        if ($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 || $privkey == '') {
+                die ("To use reCAPTCHA you must get an API key from <a href='http://recaptcha.net/api/getkey'>http://recaptcha.net/api/getkey</a>");
+        }
+
+        if ($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 ReCaptchaResponse();
+                $recaptcha_response->is_valid = false;
+                $recaptcha_response->error = 'incorrect-captcha-sol';
+                return $recaptcha_response;
+        }
+
+        $response = _recaptcha_http_post (RECAPTCHA_VERIFY_SERVER, "/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 "http://recaptcha.net/api/getkey?" .  _recaptcha_qsencode (array ('domain' => $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://mailhide.recaptcha.net/apikey'>http://mailhide.recaptcha.net/apikey</a>");
+        }
+        
+
+        $ky = pack('H*', $privkey);
+        $cryptmail = _recaptcha_aes_encrypt ($email, $ky);
+        
+        return "http://mailhide.recaptcha.net/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 $arr;
+}
+
+/**
+ * Gets html to display an email address given a public an private key.
+ * to get a key, go to:
+ *
+ * http://mailhide.recaptcha.net/apikey
+ */
+function recaptcha_mailhide_html($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]);
+
+}
+
+
+?>