Redirect bad/adults keywords in URL - php

Question

How can I redirect multiple bad/adults keyword in a URL?
I was trying to do it with htaccess, but I don't think it's good for many keyword
example:
http://example.com/mp3/sex-with-me/page/1 redirect to http://example.com/mp3/with-me/page/1
http://example.com/video/selena-gomes-porn/page/1 redirect to http://example.com/video/selena-gomes/page/1
some code from htaccess file:
RewriteRule ^mp3/(.*)-sex/page/(.*)?$ http://site.com/mp3/$1/page/$2 [R=301,L]
RewriteRule ^mp3/(.*)-sex-(.*)/page/(.*)?$ http://site.com/mp3/$1-$2/page/$3 [R=301,L]
RewriteRule ^mp3/sex-(.*)/page/(.*)?$ http://site.com/mp3/$1/page/$2 [R=301,L]
RewriteRule ^video/(.*)-porn/page/(.*)?$ http://site.com/video/$1/page/$2 [R=301,L]
RewriteRule ^video/(.*)-porn-(.*)/page/(.*)?$ http://site.com/video/$1-$2/page/$3 [R=301,L]
RewriteRule ^video/porn-(.*)/page/(.*)?$ http://site.com/video/$1/page/$2 [R=301,L]
Is it possible to do this with PHP?

Answer 1

It would be possible to do in PHP, sure... I'm just not sure it's a good idea. You could redirect every request to a PHP page, explode $_SERVER['REQUEST_URI'], run some regexes, then continue on to the page.
I see a few big issues. Firstly, why are you changing the URI but still allowing access to the site? If this is your own site, you should be filtering these words before the creation of a URI. If this is supposed to be a proxy, then why allow access to a site with flagged words in the URI? (Especially because there are many better ways to deny access to inappropriate material than a PHP filtering based on the URI)
Secondly, what do you do about the town of Middlesex, or athlete Mr. Gay? What about if a dyke breaks along the Mississippi river? If someone is writing about e-readers (Nook, i.e.) you could have a problem, too. I could circumvent your filter by adding some hyphens or other junk characters. Basically, filtering based on the contents of the URI is very problematic and not likely to work too well.
If you want to do it in PHP, it'd probably be something like this:
<?php
$uri_component = explode('/',$_SERVER['REQUEST_URI']);
foreach($uri_component as $fragment){
if(preg_match('/regex/',$fragment) echo "BAD WORD";
}
?>

Answer 2

If your site has entry point for example through index.php you can define array with bad words, searching this words in url using your array and redirect to right url if bad words will be found.
In index.php:
<?php
$badWords = array('sex','prOn','etc');
$uriParts = explode('/',$_SERVER["REQUEST_URI"]);
// build preg with bad words
$preg = '/'.implode('|',$badWords).'/is';
foreach ($uriParts as $k=>$part)
{
$uriParts[$k]=preg_replace($preg,'',$uriParts[$k]);
}
// if bad words were found
if($uri='/'.implode('/',$uriParts)!=$_SERVER["REQUEST_URI"])
{
$newUrl = 'http://'.$_SERVER["SERVER_NAME"].$uri;
// redirecting user to good url with http code 301
header("HTTP/1.1 301 Moved Permanently");
header('Location: '.$newUrl);
exit();
}
If your site has multiple entry points for example mp3.php, video.php and etc..
You can save code which you see above in file bad_words_guard.php :) and include it in your every entry file:
<?php
require_once('path/to/bad_words_guard.php');
...