正则表达式匹配子域

Question

I need a regex that matches all the subdomains of a specific domain. The content media type is unknown (i.g. may be urlencoded, json etc) So far I've got this simple regex re, err := regexp.Compile(`([-a-z0-9])+[.](.*)domain.com`)

The issue is that for a string such this below the whole string is Found instead to get the specific sudomains extracted such prefix1-prefix2.domain.com so the question is what regexp do I need to get only the subdomains without the extra string (i.e %2Fdocument...)

prefix1-prefix2.domain.com%2Fdocument%2F%3Fusp%3Dmkt_docs%26lng%3Den&followup=https%3A%2F%2Fprefix1-prefix2.domain.com%2Fdocument%2F%3Fusp%3Dmkt_docs%26lng%

Answer 1

The greedy (.*) in your regex is matching all the stuff that you don't want, you can remove that. Also, I escaped your . characters and moved your + to be inside the capture group.

Change your regex to: ([-a-z0-9]+)\.domain\.com or in the context of your code:

regexp.Compile(`([-a-z0-9]+)\.domain\.com`)

Here's a regex101 fiddle you can test it with.