International Domain Names

Question

When I navigate to aртем.example.com, the web browser will convert the URL to xn--a-jtbvok.example.com. Is there a way to convert xn--a-jtbvok back to aртем using PHP?

Currently I am using $_SERVER['HTTP_HOST'] to fetch the requested URL.

Live examples here: aртем.lekintepls.se and åäö.lekintepls.se.

I have no idea what this phenomena is called, so I'm sorry if this is a duplicate.

I would recommend using only *standard* characters in URLs, but why don't you just check if it equals `xn--a-jtbvok`? `if ($_SERVER['HTTP_HOST'] === 'xn--a-jtbvok') { /* ... */ }` — tleb, Jul 05 '15 at 20:01
I want the subdomain to be displayed on the page, just like it is now. It's literally the site's only purpose. Making checks for every possible subdomain isn't possible. — Andreas Vennström, Jul 05 '15 at 20:06
As said [here](http://stackoverflow.com/a/1916747/4255615), URLs should only contain the *standard* characters available. — tleb, Jul 05 '15 at 20:19

score 2 · Accepted Answer · answered Jul 05 '15 at 20:47

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This notation is called Punycode or IDNA (Internationalizing Domain Names in Applications).

You can use the idn_to_utf8 and idn_to_ascii to convert between to two notations.

answered Jul 05 '15 at 20:47

Dekel

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score 0 · Answer 2 · edited May 23 '17 at 11:59

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As quoted here, the RFC 1738 says that:

Thus, only alphanumerics, the special characters "$-_.+!*'(),", and reserved characters used for their reserved purposes may be used unencoded within a URL.

This suggests that unicode characters should not be used in URLs.

edited May 23 '17 at 11:59

Community

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answered Jul 05 '15 at 20:23

tleb

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International Domain Names

2 Answers2