This patch changes several internal packages to receive and pass tracing
annotations, making use of the new tracing library, so we can have
better debugging information.
Some deployments already have users that authenticate without a domain.
Today, we refuse to even consider those, and reject them at parsing time.
However, it is a use-case worth supporting, at least with some
restrictions that make the complexity manageable.
This patch changes the auth package to support authenticating users
without an "@domain" part.
Those requests will always be directly passed on to the fallback
authenticator, if available.
The dovecot fallback authenticator can already handle this case just fine.
This patch adds a new package which implements two basic primitives for
authenticating against dovecot ("user exists", and "check password").
It is still experimental/work in progress.
This patch implements an Authenticator type, which connections use to
do authentication and user existence checks.
It simplifies the abstractions (the server doesn't need to know about
userdb, or keep track of domain-userdb maps), and lays the foundation
for other types of authentication backends which will come in later
patches.
This patch implements the AUTH SMTP command, using per-domain user databases.
Note that we don't really use or check the validation for anything, this is
just implementing the command itself.
