Lesson 07 · Pulling out the userinfo

Pulling out the userinfo

When an authority carries a user component, it comes first and ends at an at-sign. Today you split that userinfo off the front of the authority, keeping the present-but-empty distinction you built earlier.

The goal

Split the userinfo before the at-sign out of the authority.

Start here - the target

TO DO

Scenario: Userinfo before the at-sign

Giventhe input "//jane:secret@example.com/"

WhenParse is called

ThenHasUserinfo is true, Userinfo is "jane:secret", and Host is "example.com"

AndParse("//@example.com") has HasUserinfo true with Userinfo "", and Parse("//example.com") has HasUserinfo false

Background

The userinfo holds user-identity data - classically user:password, though the password form is deprecated for obvious reasons. When present it sits at the front of the authority and is terminated by the first @; everything after that at-sign is the host and optional port. So split on the first @: what precedes it is the userinfo, what follows continues on to host parsing.

The same present-versus-absent care from the fragment applies here. @example.com has an empty userinfo (someone wrote the at-sign but nothing before it), while example.com has no userinfo at all - and HasUserinfo is what tells them apart. Splitting on the first @ matters too, since a colon or later characters in the host are not your concern yet; the userinfo boundary is simply that first at-sign. With userinfo removed, the remaining string is host plus a possible port, which the next lesson divides.

Make it work

// userinfo is everything before the FIRST '@' in the authority
if i := strings.IndexByte(a, '@'); i >= 0 {
  u.Userinfo = a[:i]
  u.HasUserinfo = true
  a = a[i+1:] // host (and maybe port) is what remains
}

CheckpointDONE

parseAuthority now separates the userinfo from the host. Commit and stop here.