Re: [RFC] pop3: support `?limit=$NUM' parameter in mailbox name

[Konstantin Ryabitsev <konstantin@linuxfoundation.org>]

On Wed, Sep 13, 2023 at 06:20:40AM +0000, Eric Wong wrote:
> Eric Wong <e@80x24.org> wrote:
> > I'm not sure if `?' or `=' are allowed characters in POP3
> > mailbox names.  In fact, I can't find any information on
> > valid characters allowed in RFC 1081 nor RFC 1939.

It's a username, though, not mailbox name? There's no restriction on the
characters or length of the username, though I'm guessing some UI clients may
have their own limits regarding the length of the username field.

> Of course, the parameters and all manner of special characters
> can also be placed the password, so `anonymous?limit=1000'.
> 
> But somehow putting parameters in the "password" (even a
> well-known and obvious one) feels wrong.

What if we move the uuid into the password field -- it seems it belongs there
anyway, as it's tied to the user cookie.

username: newsgroup.name?params
password: $(uuidgen)

So, in my example it becomes:

username: org.kernel.vger.git?limit=1000
password: 288e5e35-1a35-46ef-b3d5-6d94c20aeab8

This could be backward-compatible with the current implementation -- if there
is an @ in the username field, then the cookie is based on what's preceding
it. If there's none, then we use the password field (unless it's "anonymous").

This way we're less likely to run into any problems with username length
limitations set by MUAs.

-K