Underscores in subdomains?

[tasinet]

Are you interested in supporting underscores in subdomains? They are quite legal and somewhat common, and this lib (like many) throws an unsupported character error in such cases.

I have a rough fix in my fork, I can PR if you want.

[randalpinto]

Ditto, _dmarc.somedomain.com is a good example of that.

[jhnns]

Sure 👍

While doing a quick research, I just stumbled upon https://stackoverflow.com/a/2183140
Maybe we shouldn't validate the characters after all... what do you think?

Anyway, you can send my a PR adding _ as allowed character for now

[jhnns]

I changed my mind. I'm going to allow 2 different validation modes:

export enum Validation {
  /**
   * Allows any octets as labels
   * but still restricts the length of labels and the overall domain.
   *
   * @see https://www.rfc-editor.org/rfc/rfc2181#section-11
   **/
  Lax = "LAX",

  /**
   * Only allows ASCII letters, digits and hyphens (aka LDH),
   * forbids hyphens at the the beginning or end of a label
   * and requires top-level domain names not to be all-numeric.
   *
   * This is the default if no validation is configured.
   *
   * @see https://datatracker.ietf.org/doc/html/rfc3696#section-2
   */
  Strict = "STRICT",
}

What do you think?

[randalpinto]

i like the idea, STRICT being the default?

[jhnns]

Shipped with v5.0.0 🚀

import { parseDomain, Validation } from "parse-domain";

const parseResult = parseDomain("_jabber._tcp.gmail.com", {
  validation: Validation.Lax,
});