libtld, or the TLD library was built in order to help you extract the TLD from a URI. This allows you to extract the exact domain name, sub-domains, and all the TLD (top level, second level, third level, etc.). libtld offers one function: tld(), which gives you a way to extract the TLD from any URI. The result is the offset where the TLD starts. This gives you enough information to extract everything else you need.