How to check whether hostname is domain name in Go?

Question

How can I check whether URL.Hostname is a valid domain name? I am searching for the exact same behaviour as URI.CheckHostName in the .NET framework.

Currently, there is no solution using standard library only. You need to use third party library/regex. However, if you need to support *internationalized domain name*, the task may not trivial. See [https://stackoverflow.com/questions/11809631/fully-qualified-domain-name-validation](https://stackoverflow.com/questions/11809631/fully-qualified-domain-name-validation), [https://stackoverflow.com/questions/3523028/valid-characters-of-a-hostname](https://stackoverflow.com/questions/3523028/valid-characters-of-a-hostname) — putu, Jan 13 '18 at 11:14

score 4 · Answer 1 · answered Jun 29 '18 at 16:07

4

See my code here.

The function checks if the provided domain name is valid relative to the rules. It doesn't check if the domain name exist.

answered Jun 29 '18 at 16:07

chmike

score 1 · Answer 2 · answered Jan 13 '18 at 11:10

1

The function IsDNSName from the govalidator package should do what you want. For details on installing it, see the README.

answered Jan 13 '18 at 11:10

phlummox

It allows underscore in domain names which is wrong. See RFC1034 section 3.5. A later change to this RFC is to allow digits as first label character. The TLD label can't start with a digit to avoid confusion between domain names and IPv4 addresses. – chmike Jun 26 '18 at 08:16

2 Answers2