<?php
/**
* @brief Trackbacks/Pingbacks sender and server
*
* Sends and receives trackbacks/pingbacks.
* Also handles trackbacks/pingbacks auto discovery.
*
* @package Dotclear
* @subpackage Core
*
* @copyright Olivier Meunier & Association Dotclear
* @copyright GPL-2.0-only
*/
if (!defined('DC_RC_PATH')) {
return;
}
class dcTrackback
{
public $core; ///< <b>dcCore</b> dcCore instance
public $table; ///< <b>string</b> done pings table name
/**
* Object constructor
*
* @param dcCore $core dcCore instance
*/
public function __construct(dcCore $core)
{
$this->core = &$core;
$this->table = $this->core->prefix . 'ping';
}
/// @name Send
//@{
/**
* Get all pings sent for a given post.
*
* @param integer $post_id The post identifier
*
* @return record The post pings.
*/
public function getPostPings($post_id)
{
$strReq = 'SELECT ping_url, ping_dt ' .
'FROM ' . $this->table . ' ' .
'WHERE post_id = ' . (int) $post_id;
return $this->core->con->select($strReq);
}
/**
* Sends a ping to given <var>$url</var>.
*
* @param string $url The url
* @param string $post_id The post identifier
* @param string $post_title The post title
* @param string $post_excerpt The post excerpt
* @param string $post_url The post url
*
* @throws Exception
*
* @return mixed false if error
*/
public function ping($url, $post_id, $post_title, $post_excerpt, $post_url)
{
if ($this->core->blog === null) {
return false;
}
$post_id = (int) $post_id;
# Check for previously done trackback
$strReq = 'SELECT post_id, ping_url FROM ' . $this->table . ' ' .
'WHERE post_id = ' . $post_id . ' ' .
"AND ping_url = '" . $this->core->con->escape($url) . "' ";
$rs = $this->core->con->select($strReq);
if (!$rs->isEmpty()) {
throw new Exception(sprintf(__('%s has still been pinged'), $url));
}
$ping_parts = explode('|', $url);
$ping_msg = '';
# Maybe a webmention
if (count($ping_parts) == 3) {
$payload = http_build_query([
'source' => $post_url,
'target' => $ping_parts[1],
]);
try {
$http = self::initHttp($ping_parts[0], $path);
$http->setMoreHeader('Content-Type: application/x-www-form-urlencoded');
$http->post($path, $payload, 'UTF-8');
# Read response status
$status = $http->getStatus();
$ping_error = '0';
} catch (Exception $e) {
throw new Exception(__('Unable to ping URL'));
}
if (!in_array($status, ['200', '201', '202'])) {
$ping_error = $http->getStatus();
$ping_msg = __('Bad server response code');
}
}
# No, let's walk by the trackback way
elseif (count($ping_parts) < 2) {
$data = [
'title' => $post_title,
'excerpt' => $post_excerpt,
'url' => $post_url,
'blog_name' => trim(html::escapeHTML(html::clean($this->core->blog->name))),
//,'__debug' => false
];
# Ping
try {
$http = self::initHttp($url, $path);
$http->post($path, $data, 'UTF-8');
$res = $http->getContent();
} catch (Exception $e) {
throw new Exception(__('Unable to ping URL'));
}
$pattern = '|<response>.*<error>(.*)</error>(.*)' .
'(<message>(.*)</message>(.*))?' .
'</response>|msU';
if (!preg_match($pattern, $res, $match)) {
throw new Exception(sprintf(__('%s is not a ping URL'), $url));
}
$ping_error = trim((string) $match[1]);
$ping_msg = (!empty($match[4])) ? $match[4] : '';
}
# Damnit ! Let's play pingback
else {
try {
$xmlrpc = new xmlrpcClient($ping_parts[0]);
$res = $xmlrpc->query('pingback.ping', $post_url, $ping_parts[1]);
$ping_error = '0';
} catch (xmlrpcException $e) {
$ping_error = $e->getCode();
$ping_msg = $e->getMessage();
} catch (Exception $e) {
throw new Exception(__('Unable to ping URL'));
}
}
if ($ping_error != '0') {
throw new Exception(sprintf(__('%s, ping error:'), $url) . ' ' . $ping_msg);
}
# Notify ping result in database
$cur = $this->core->con->openCursor($this->table);
$cur->post_id = $post_id;
$cur->ping_url = $url;
$cur->ping_dt = date('Y-m-d H:i:s');
$cur->insert();
}
//@}
/// @name Receive
//@{
/**
* Receives a trackback and insert it as a comment of given post.
*
* @param integer $post_id The post identifier
*/
public function receiveTrackback($post_id)
{
header('Content-Type: text/xml; charset=UTF-8');
if (empty($_POST)) {
http::head(405, 'Method Not Allowed');
echo
'<?xml version="1.0" encoding="utf-8"?>' . "\n" .
"<response>\n" .
" <error>1</error>\n" .
" <message>POST request needed</message>\n" .
'</response>';
return;
}
$post_id = (int) $post_id;
$title = !empty($_POST['title']) ? $_POST['title'] : '';
$excerpt = !empty($_POST['excerpt']) ? $_POST['excerpt'] : '';
$url = !empty($_POST['url']) ? $_POST['url'] : '';
$blog_name = !empty($_POST['blog_name']) ? $_POST['blog_name'] : '';
$charset = '';
$comment = '';
$err = false;
$msg = '';
if ($this->core->blog === null) {
$err = true;
$msg = 'No blog.';
} elseif ($url == '') {
$err = true;
$msg = 'URL parameter is required.';
} elseif ($blog_name == '') {
$err = true;
$msg = 'Blog name is required.';
}
if (!$err) {
$post = $this->core->blog->getPosts(['post_id' => $post_id, 'post_type' => '']);
if ($post->isEmpty()) {
$err = true;
$msg = 'No such post.';
} elseif (!$post->trackbacksActive()) {
$err = true;
$msg = 'Trackbacks are not allowed for this post or weblog.';
}
$url = trim(html::clean($url));
if ($this->pingAlreadyDone($post->post_id, $url)) {
$err = true;
$msg = 'The trackback has already been registered';
}
}
if (!$err) {
$charset = self::getCharsetFromRequest();
if (!$charset) {
$charset = self::detectCharset($title . ' ' . $excerpt . ' ' . $blog_name);
}
if (strtolower($charset) != 'utf-8') {
$title = iconv($charset, 'UTF-8', $title);
$excerpt = iconv($charset, 'UTF-8', $excerpt);
$blog_name = iconv($charset, 'UTF-8', $blog_name);
}
$title = trim(html::clean($title));
$title = html::decodeEntities($title);
$title = html::escapeHTML($title);
$title = text::cutString($title, 60);
$excerpt = trim(html::clean($excerpt));
$excerpt = html::decodeEntities($excerpt);
$excerpt = preg_replace('/\s+/ms', ' ', $excerpt);
$excerpt = text::cutString($excerpt, 252);
$excerpt = html::escapeHTML($excerpt) . '...';
$blog_name = trim(html::clean($blog_name));
$blog_name = html::decodeEntities($blog_name);
$blog_name = html::escapeHTML($blog_name);
$blog_name = text::cutString($blog_name, 60);
try {
$this->addBacklink($post_id, $url, $blog_name, $title, $excerpt, $comment);
} catch (Exception $e) {
$err = 1;
$msg = 'Something went wrong : ' . $e->getMessage();
}
}
$resp = '<?xml version="1.0" encoding="utf-8"?>' . "\n" .
"<response>\n" .
' <error>' . (int) $err . "</error>\n";
if ($msg) {
$resp .= ' <message>' . $msg . "</message>\n";
}
if (!empty($_POST['__debug'])) {
$resp .= " <debug>\n" .
' <title>' . $title . "</title>\n" .
' <excerpt>' . $excerpt . "</excerpt>\n" .
' <url>' . $url . "</url>\n" .
' <blog_name>' . $blog_name . "</blog_name>\n" .
' <charset>' . $charset . "</charset>\n" .
' <comment>' . $comment . "</comment>\n" .
" </debug>\n";
}
echo $resp . '</response>';
}
/**
* Receives a pingback and insert it as a comment of given post.
*
* @param string $from_url Source URL
* @param string $to_url Target URL
*
* @throws Exception
*
* @return string
*/
public function receivePingback($from_url, $to_url)
{
try {
$posts = $this->getTargetPost($to_url);
if ($this->pingAlreadyDone($posts->post_id, $from_url)) {
throw new Exception(__('Don\'t repeat yourself, please.'), 48);
}
$remote_content = $this->getRemoteContent($from_url);
# We want a title...
if (!preg_match('!<title>([^<].*?)</title>!mis', $remote_content, $m)) {
throw new Exception(__('Where\'s your title?'), 0);
}
$title = trim(html::clean($m[1]));
$title = html::decodeEntities($title);
$title = html::escapeHTML($title);
$title = text::cutString($title, 60);
$blog_name = $this->getSourceName($remote_content);
preg_match('!<body[^>]*?>(.*)?</body>!msi', $remote_content, $m);
$source = $m[1];
$source = preg_replace('![\r\n\s]+!ms', ' ', $source);
$source = preg_replace("/<\/*(h\d|p|th|td|li|dt|dd|pre|caption|input|textarea|button)[^>]*>/", "\n\n", $source);
$source = strip_tags($source, '<a>');
$source = explode("\n\n", $source);
$excerpt = '';
foreach ($source as $line) {
if (strpos($line, $to_url) !== false) {
if (preg_match('!<a[^>]+?' . $to_url . '[^>]*>([^>]+?)</a>!', $line, $m)) {
$excerpt = strip_tags($line);
break;
}
}
}
if ($excerpt) {
$excerpt = '(…) ' . text::cutString(html::escapeHTML($excerpt), 200) . ' (…)';
} else {
$excerpt = '(…)';
}
$this->addBacklink($posts->post_id, $from_url, $blog_name, $title, $excerpt, $comment);
} catch (Exception $e) {
throw new Exception(__('Sorry, an internal problem has occured.'), 0);
}
return __('Thanks, mate. It was a pleasure.');
}
/**
* Receives a webmention and insert it as a comment of given post.
*
* NB: plugin Fair Trackback check source content to find url.
*
* @throws Exception
*/
public function receiveWebmention()
{
$err = $post_id = false;
header('Content-Type: text/html; charset=UTF-8');
try {
# Check if post and target are valid URL
if (empty($_POST['source']) || empty($_POST['target'])) {
throw new Exception('Source or target is not valid', 0);
}
$from_url = urldecode($_POST['source']);
$to_url = urldecode($_POST['target']);
self::checkURLs($from_url, $to_url);
# Try to find post
$posts = $this->getTargetPost($to_url);
$post_id = $posts->post_id;
# Check if it's an updated mention
if ($this->pingAlreadyDone($post_id, $from_url)) {
$this->delBacklink($post_id, $from_url);
}
# Create a comment for received webmention
$remote_content = $this->getRemoteContent($from_url);
# We want a title...
if (!preg_match('!<title>([^<].*?)</title>!mis', $remote_content, $m)) {
throw new Exception(__('Where\'s your title?'), 0);
}
$title = trim(html::clean($m[1]));
$title = html::decodeEntities($title);
$title = html::escapeHTML($title);
$title = text::cutString($title, 60);
$blog_name = $this->getSourceName($remote_content);
preg_match('!<body[^>]*?>(.*)?</body>!msi', $remote_content, $m);
$source = $m[1];
$source = preg_replace('![\r\n\s]+!ms', ' ', $source);
$source = preg_replace("/<\/*(h\d|p|th|td|li|dt|dd|pre|caption|input|textarea|button)[^>]*>/", "\n\n", $source);
$source = strip_tags($source, '<a>');
$source = explode("\n\n", $source);
$excerpt = '';
foreach ($source as $line) {
if (strpos($line, $to_url) !== false) {
if (preg_match('!<a[^>]+?' . $to_url . '[^>]*>([^>]+?)</a>!', $line, $m)) {
$excerpt = strip_tags($line);
break;
}
}
}
if ($excerpt) {
$excerpt = '(…) ' . text::cutString(html::escapeHTML($excerpt), 200) . ' (…)';
} else {
$excerpt = '(…)';
}
$this->addBacklink($post_id, $from_url, $blog_name, $title, $excerpt, $comment);
# All done, thanks
$code = $this->core->blog->settings->system->trackbacks_pub ? 200 : 202;
http::head($code);
return;
} catch (Exception $e) {
$err = $e->getMessage();
}
http::head(400);
echo $err ?: 'Something went wrong.';
}
/**
* Check if a post previously received a ping a from an URL.
*
* @param integer $post_id The post identifier
* @param string $from_url The from url
*
* @return bool
*/
private function pingAlreadyDone($post_id, $from_url)
{
$params = [
'post_id' => $post_id,
'comment_site' => $from_url,
'comment_trackback' => 1,
];
$rs = $this->core->blog->getComments($params, true);
if ($rs && !$rs->isEmpty()) {
return ($rs->f(0));
}
return false;
}
/**
* Create a comment marked as trackback for a given post.
*
* @param integer $post_id The post identifier
* @param string $url The url
* @param string $blog_name The blog name
* @param string $title The title
* @param string $excerpt The excerpt
* @param string $comment The comment
*/
private function addBacklink($post_id, $url, $blog_name, $title, $excerpt, &$comment)
{
if (empty($blog_name)) {
// Let use title as text link for this backlink
$blog_name = ($title ?: 'Anonymous blog');
}
$comment = "<!-- TB -->\n" .
'<p><strong>' . ($title ?: $blog_name) . "</strong></p>\n" .
'<p>' . $excerpt . '</p>';
$cur = $this->core->con->openCursor($this->core->prefix . 'comment');
$cur->comment_author = (string) $blog_name;
$cur->comment_site = (string) $url;
$cur->comment_content = (string) $comment;
$cur->post_id = $post_id;
$cur->comment_trackback = 1;
$cur->comment_status = $this->core->blog->settings->system->trackbacks_pub ? 1 : -1;
$cur->comment_ip = http::realIP();
# --BEHAVIOR-- publicBeforeTrackbackCreate
$this->core->callBehavior('publicBeforeTrackbackCreate', $cur);
if ($cur->post_id) {
$comment_id = $this->core->blog->addComment($cur);
# --BEHAVIOR-- publicAfterTrackbackCreate
$this->core->callBehavior('publicAfterTrackbackCreate', $cur, $comment_id);
}
}
/**
* Delete previously received comment made from an URL for a given post.
*
* @param integer $post_id The post identifier
* @param string $url The url
*/
private function delBacklink($post_id, $url)
{
$this->core->con->execute(
'DELETE FROM ' . $this->core->prefix . 'comment ' .
'WHERE post_id = ' . ((int) $post_id) . ' ' .
"AND comment_site = '" . $this->core->con->escape((string) $url) . "' " .
'AND comment_trackback = 1 '
);
}
/**
* Gets the charset from HTTP headers.
*
* @param string $header The header
*
* @return mixed The charset from request.
*/
private static function getCharsetFromRequest($header = '')
{
if (!$header && isset($_SERVER['CONTENT_TYPE'])) {
$header = $_SERVER['CONTENT_TYPE'];
}
if ($header) {
if (preg_match('|charset=([a-zA-Z0-9-]+)|', $header, $m)) {
return $m[1];
}
}
}
/**
* Detect encoding.
*
* @param string $content The content
*
* @return string
*/
private static function detectCharset($content)
{
return mb_detect_encoding(
$content,
'UTF-8,ISO-8859-1,ISO-8859-2,ISO-8859-3,' .
'ISO-8859-4,ISO-8859-5,ISO-8859-6,ISO-8859-7,ISO-8859-8,' .
'ISO-8859-9,ISO-8859-10,ISO-8859-13,ISO-8859-14,ISO-8859-15'
);
}
/**
* Retrieve local post from a given URL.
*
* @param string $to_url To url
*
* @throws Exception
*
* @return mixed The target post.
*/
private function getTargetPost($to_url)
{
$reg = '!^' . preg_quote($this->core->blog->url) . '(.*)!';
$type = $args = $next = '';
# Are you dumb?
if (!preg_match($reg, $to_url, $m)) {
throw new Exception(__('Any chance you ping one of my contents? No? Really?'), 0);
}
# Does the targeted URL look like a registered post type?
$url_part = $m[1];
$p_type = '';
$post_types = $this->core->getPostTypes();
$post_url = '';
foreach ($post_types as $k => $v) {
$reg = '!^' . preg_quote(str_replace('%s', '', $v['public_url'])) . '(.*)!';
if (preg_match($reg, $url_part, $n)) {
$p_type = $k;
$post_url = $n[1];
break;
}
}
if (empty($p_type)) {
throw new Exception(__('Sorry but you can not ping this type of content.'), 33);
}
# Time to see if we've got a winner...
$params = [
'post_type' => $p_type,
'post_url' => $post_url,
];
$posts = $this->core->blog->getPosts($params);
# Missed!
if ($posts->isEmpty()) {
throw new Exception(__('Oops. Kinda "not found" stuff. Please check the target URL twice.'), 33);
}
# Nice try. But, sorry, no.
if (!$posts->trackbacksActive()) {
throw new Exception(__('Sorry, dude. This entry does not accept pingback at the moment.'), 33);
}
return $posts;
}
/**
* Returns content of a distant page.
*
* @param string $from_url Target URL
*
* @throws Exception
*
* @return string
*/
private function getRemoteContent($from_url)
{
$http = self::initHttp($from_url, $from_path);
# First round : just to be sure the ping comes from an acceptable resource type.
$http->setHeadersOnly(true);
$http->get($from_path);
$c_type = explode(';', $http->getHeader('content-type'));
# Bad luck. Bye, bye...
if (!in_array($c_type[0], ['text/html', 'application/xhtml+xml'])) {
throw new Exception(__('Your source URL does not look like a supported content type. Sorry. Bye, bye!'), 0);
}
# Second round : let's go fetch and parse the remote content
$http->setHeadersOnly(false);
$http->get($from_path);
$remote_content = $http->getContent();
# Convert content charset
$charset = self::getCharsetFromRequest($http->getHeader('content-type'));
if (!$charset) {
$charset = self::detectCharset($remote_content);
}
if (strtolower($charset) != 'utf-8') {
$remote_content = iconv($charset, 'UTF-8', $remote_content);
}
return $remote_content;
}
//@}
/// @name Discover
//@{
/**
* Returns an array containing all discovered trackbacks URLs in <var>$text</var>.
*
* @param string $text The text
*
* @return array
*/
public function discover($text)
{
$res = [];
foreach ($this->getTextLinks($text) as $link) {
if (($url = $this->getPingURL($link)) !== null) {
$res[] = $url;
}
}
return $res;
}
/**
* Try to find source blog name or author from remote HTML page content
* Used when receive a webmention or a pingback
*
* @param string $content The content
*/
private function getSourceName($content)
{
// Clean text utility function
$clean = fn ($text, $size = 255) => text::cutString(html::escapeHTML(html::decodeEntities(html::clean(trim($text)))), $size);
// First step: look for site name
// ------------------------------
// Try to find social media metadata
// Facebook
if (preg_match('!<meta\sproperty="og:site_name"\scontent="([^<].*?)"\s?\/?>!msi', $content, $m)) {
return $clean($m[1]);
}
// Second step: look for author
// ----------------------------
// Try to find social media metadata
// Twitter
if (preg_match('!<meta\sname="twitter:site"\scontent="([^<].*?)"\s?\/?>!msi', $content, $m)) {
return $clean($m[1]);
}
// Try to find a <meta name="author" content="???" />
if (preg_match('!<meta\sname="author"\scontent="([^<].*?)"\s?\/?>!msi', $content, $m)) {
return $clean($m[1]);
}
return '';
}
/**
* Find links into a text.
*
* @param string $text The text
*
* @return array The text links.
*/
private function getTextLinks($text)
{
$res = [];
# href attribute on "a" tags
if (preg_match_all('/<a ([^>]+)>/ms', $text, $match, PREG_SET_ORDER)) {
for ($i = 0; $i < count($match); $i++) {
if (preg_match('/href="((https?:\/)?\/[^"]+)"/ms', $match[$i][1], $matches)) {
$res[$matches[1]] = 1;
}
}
}
unset($match);
# cite attributes on "blockquote" and "q" tags
if (preg_match_all('/<(blockquote|q) ([^>]+)>/ms', $text, $match, PREG_SET_ORDER)) {
for ($i = 0; $i < count($match); $i++) {
if (preg_match('/cite="((https?:\/)?\/[^"]+)"/ms', $match[$i][2], $matches)) {
$res[$matches[1]] = 1;
}
}
}
return array_keys($res);
}
/**
* Check remote header/content to find API trace.
*
* @param string $url The url
*
* @return mixed The ping url.
*/
private function getPingURL($url)
{
if (strpos($url, '/') === 0) {
$url = http::getHost() . $url;
}
try {
$http = self::initHttp($url, $path);
$http->get($path);
$page_content = $http->getContent();
$pb_url = $http->getHeader('x-pingback');
$wm_url = $http->getHeader('link');
} catch (Exception $e) {
return false;
}
# Let's check for an elderly trackback data chunk...
$pattern_rdf = '/<rdf:RDF.*?>.*?' .
'<rdf:Description\s+(.*?)\/>' .
'.*?<\/rdf:RDF>' .
'/msi';
preg_match_all($pattern_rdf, $page_content, $rdf_all, PREG_SET_ORDER);
$url_path = parse_url($url, PHP_URL_PATH);
$sanitized_url = str_replace($url_path, html::sanitizeURL($url_path), $url);
for ($i = 0; $i < count($rdf_all); $i++) {
$rdf = $rdf_all[$i][1];
if (preg_match('/dc:identifier="' . preg_quote($url, '/') . '"/msi', $rdf) || preg_match('/dc:identifier="' . preg_quote($sanitized_url, '/') . '"/msi', $rdf)) {
if (preg_match('/trackback:ping="(.*?)"/msi', $rdf, $tb_link)) {
return $tb_link[1];
}
}
}
# No trackback ? OK, let see if we've got a X-Pingback header and it's a valid URL, it will be enough
if ($pb_url && filter_var($pb_url, FILTER_VALIDATE_URL) && preg_match('!^https?:!', $pb_url)) {
return $pb_url . '|' . $url;
}
# No X-Pingback header. A link rel=pingback, maybe ?
$pattern_pingback = '!<link rel="pingback" href="(.*?)"( /)?>!msi';
if (preg_match($pattern_pingback, $page_content, $m)) {
$pb_url = $m[1];
if (filter_var($pb_url, FILTER_VALIDATE_URL) && preg_match('!^https?:!', $pb_url)) {
return $pb_url . '|' . $url;
}
}
# Nothing, let's try webmention. Only support x/html content
if ($wm_url) {
$type = explode(';', $http->getHeader('content-type'));
if (!in_array($type[0], ['text/html', 'application/xhtml+xml'])) {
$wm_url = false;
}
}
# Check HTTP headers for a Link: <ENDPOINT_URL>; rel="webmention"
$wm_api = false;
if ($wm_url) {
if (preg_match('~<((?:https?://)?[^>]+)>; rel="?(?:https?://webmention.org/?|webmention)"?~', $wm_url, $match)) {
if (filter_var($match[1], FILTER_VALIDATE_URL) && preg_match('!^https?:!', $match[1])) {
$wm_api = $match[1];
}
}
}
# Else check content for <link href="ENDPOINT_URL" rel="webmention" />
if ($wm_url && !$wm_api) {
$content = preg_replace('/<!--(.*)-->/Us', '', $page_content);
if (preg_match('/<(?:link|a)[ ]+href="([^"]*)"[ ]+rel="[^" ]* ?webmention ?[^" ]*"[ ]*\/?>/i', $content, $match)
|| preg_match('/<(?:link|a)[ ]+rel="[^" ]* ?webmention ?[^" ]*"[ ]+href="([^"]*)"[ ]*\/?>/i', $content, $match)) {
$wm_api = $match[1];
}
}
# We have a winner, let's add some tricks to make diference
if ($wm_api) {
return $wm_api . '|' . $url . '|webmention';
}
}
//@}
/**
* HTTP helper.
*
* @param string $url The url
* @param string $path The path
*
* @return netHttp
*/
private static function initHttp($url, &$path)
{
$client = netHttp::initClient($url, $path);
$client->setTimeout(DC_QUERY_TIMEOUT);
$client->setUserAgent('Dotclear - https://dotclear.org/');
$client->useGzip(false);
$client->setPersistReferers(false);
return $client;
}
/**
* URL helper.
*
* @param string $from_url The from url
* @param string $to_url To url
*
* @throws Exception
*/
public static function checkURLs($from_url, $to_url)
{
if (!(filter_var($from_url, FILTER_VALIDATE_URL) && preg_match('!^https?://!', $from_url))) {
throw new Exception(__('No valid source URL provided? Try again!'), 0);
}
if (!(filter_var($to_url, FILTER_VALIDATE_URL) && preg_match('!^https?://!', $to_url))) {
throw new Exception(__('No valid target URL provided? Try again!'), 0);
}
if (html::sanitizeURL(urldecode($from_url)) == html::sanitizeURL(urldecode($to_url))) {
throw new Exception(__('LOL!'), 0);
}
}
}