disallow some domain names, allow others

For example there are URLs http://www.subdomain1.domain.com.uk and http://www.subdomain2.domain.uk, from these URLs I need to extract only the name subdomain1 or subdomain2.

But if I receive http://www.subdomain3.co.uk or http://www.subdomain4.com I need to get the whole URL like subdomain3.co.uk or subdomain4.com.

My expres开发者_运维知识库sion: ^http:\/\/(?:www\.)?((?!SubdomainToNegate|www).*)((?!\.domain\.com\.uk|\.domain\.uk).*)$

Expression catches whole URL.

My situation is shown better over there: http://www.rubular.com/r/B1iOUoUq33

^http:\/\/(?:www\.)?((?!SubdomainToNegate|www)[^\.]*)((?!\.domain\.com\.uk|\.domain\.uk).*)$

difference is this

(?!SubdomainToNegate|www)[^\.]*

instead of this

(?!SubdomainToNegate|www)\.*

finally found solution:

http:\/\/(?:www\.)?((?:(?!domain.com.uk|domain.uk)[^\s.]+)(?:\.(?!domain.com.uk|domain.uk)[^\s.]+)*)