rewrite/mask external link inside article - php

Question

I want to rewrite/mask all external url in my article and also add nofollow and target="_blank". So that original link to the external site is get encrypted/ masked/ rewritten.
For example:
original link: www.google.com
rewrite it to: www.mydomain.com?goto=google.com
There is a plugin for joomla which rewrite external link: rewrite plugin.
But I am not using joomla. Please have a look at above plugin, It does exactly what I am looking for.
What I want?
$article = "hello this is example article I want to replace all external link http://google.com";
$host = substr($_SERVER['HTTP_HOST'], 0, 4) == 'www.' ? substr($_SERVER['HTTP_HOST'], 0) : $_SERVER['HTTP_HOST'];
if (thisIsNotMyWebsite){
replace external url
}

Answer 1

You can use DOMDocument to parse and traverse the document.
function rewriteExternal($html) {
// The url for your redirection script
$prefix = 'http://www.example.com?goto=';
// a regular expression to determine if
// this link is within your site, edit for your
// domain or other needs
$is_internal = '/(?:^\/|^\.\.\/)|example\.com/';
$dom = new DOMDocument();
// Parse the HTML into a DOM
$dom->loadHTML($html);
$links = $dom->getElementsByTagName('a');
foreach ($links as $link) {
$href = $link->getAttribute('href');
if (!preg_match($is_internal, $href)) {
$link->getAttributeNode('href')->value = $prefix . $href;
$link->setAttributeNode(new DOMAttr('rel', 'nofollow'));
$link->setAttributeNode(new DOMAttr('target', '_blank'));
}
}
// returns the updated HTML or false if there was an error
return $dom->saveHTML();
}
This approach will be much more reliable than using a regular expression based solution since it actually parses the DOM for you instead of relying on a often-fragile regex.

Answer 2

something like:
<?php
$html ='1224 google 567';
$tracking_string = 'http://example.com/track.php?url=';
$html = preg_replace('#(<a[^>]+href=")(http|https)([^>" ]+)("?[^>]*>)#is','\\1'.$tracking_string.'\\2\\3\\4',$html);
echo $html;
in action here: http://codepad.viper-7.com/7BYkoc
--my last update
<?php
$html =' 1224 google 567';
$tracking_string = 'http://example.com/track.php?url=';
$html = preg_replace('#(<a[^>]+)(href=")(http|https)([^>" ]+)("?[^>]*>)#is','\\1 nofollow target="_blank" \\2'.$tracking_string.'\\3\\4\\5',$html);
echo $html;
http://codepad.viper-7.com/JP8sUk