Adjust oEmbed regex for Slideshare

[Latz]

The current regex in class-oembed.php for slideshare assumes that the URL is "www.slideshare.net" or "slideshare.net".
Accessing slideshare from Germany I experienced that the URL is "de.slideshare.net". I assume there are others for various languages.

This patch changes
'#https?://(www\.)?slideshare\.net/.*#i'
to
'#https?://(.+\.)?slideshare\.net/.*#i'

so that these URLs permitted to be embedded.

[johnbillion]

There is indeed a language switcher at the bottom of slideshare.net which changes the subdomain.

I think that regex needs to be tightened up a little. It a cursory glance, it looks like it'll be greedy.

#https?://([a-z]+\.)?slideshare\.net/.*#i will probably suffice.

[Latz]

Make new regex less greedy.

[Latz]

I think that regex needs to be tightened up a little. It a cursory glance, it looks like it'll be greedy.

#https?://([a-z]+\.)?slideshare\.net/.*#i will probably suffice.

Yeah, you're right, I tend to make regexes too greedy. I adjusted the patch.

[wonderboymusic]

.+?\. would work for arbitrary subdomains, so that www3 and the like would work, will test for fun.

[nacin]

At this point, we're already trusting mostly arbitrary subdomains and we already use (.+\.) elsewhere, so we might as well stay consistent.

[wonderboymusic]

In 29735:

Allow arbitrary subdomains for the oEmbed endpoint for Slideshare.

Props Latz.
Fixes #29427.