Out customers can enter websites from domain names. They also can enter mailadresses from their contacts.

Know we need to find customers which websited whoose domain can be associated to the domains of the mailadresses.

So my idea is to extract the host from the webadress and from the url and compare them

So what's the most reliable algorithm to get the hostname from a url?

for example a host can be:

```
foo.com
www.foo.com
http://foo.com
https://foo.com
https://www.foo.com

```

The result should always be foo.com