Add more chat protocol support to filter_allowed_protocols

Adding a skype link to the site footer via the Site Information page like this:

<a href="skype:username?call">Call username with skype</a>

Will render the following code:

<a href="username?call">Call username with skype</a>

There is no option to select Full HTML as the filter for the footer region, is it possible to make skype links work with Filtered HTML?

The bad guy is filter_xss_bad_protocol(), which allows for all kinds of protocols, but not skype. Because it uses a (hidden) variable, you can change it by hand using one of the following methods: This works or D5 as well.

1. If you have devel module, execute this code in the "Execute PHP" block:

variable_set('filter_allowed_protocols', array('http', 'https', 'ftp', 'news', 'nntp', 'telnet', 'mailto', 'irc', 'ssh', 'sftp', 'webcal', 'rtsp', 'skype'));

2. Or you can hardcode the value in your settings.php file. Scroll down to the bottom of the settings.php file and you'll find a commented out section of code like this:

# $conf = array(
#   'site_name' => 'My Drupal site',
#   'theme_default' => 'minnelli',
#   'anonymous' => 'Visitor',
# );

Change this to:

  $conf = array(
    'filter_allowed_protocols' => array('http', 'https', 'ftp', 'news', 'nntp', 'telnet', 'mailto', 'irc', 'ssh', 'sftp', 'webcal', 'rtsp', 'skype');
  );

Thanks Maarten, worked a treat!

There's a typo in the code you should to paste into settings.php, as said here: http://drupal.org/node/185350#comment-616830

Besides, in my site the code won't work with the around it, so I use the following now (and it works):

$conf = array(
'filter_allowed_protocols' => array('http', 'https', 'ftp', 'news', 'nntp', 'telnet', 'mailto', 'irc', 'ssh', 'sftp', 'webcal', 'mms', 'rstp', 'skype'),
);

There are a few chat protocol formats we should add since we include irc://

skype://
gtalk://
xmpp:// (jabber)

I doubt this would gain any support for proprietary chats like gtalk and skype, so I'm going to mark this back as fixed. Note I've also created a small D6 and D7 module http://drupal.org/project/filter_protocols to expose this variables settings.

How could be explained the following transformation of a correct link?

<a href="skype:username?call">Call username with skype</a>

Expected result:
<a href="username?call">Call username with skype</a>

Rendered code:
<a href="username?call=">Call username with skype</a>

Any piece of advice is more than welcome.

I try to add a Link Field and the field use the itms-services protocol, I want to use the filter_protocol module to add the itms-services protocol,but failed.

Not sure it can be fixed as @Dave Reid said. If it can, please explain how.

Drupal 8 solution?

For D8 update the file at /sites/default/service.yml

parameters:
filter_protocols: [http, https, ftp, news, nntp, tel, telnet, mailto, irc, ssh, sftp, webcal, rtsp, sip, callto]