Today, the parsing functions are stand-alone since they don't need
anything from the resolver.
But in future patches, that will change.
In anticipation of that, move those functions to be methods of the
resolver.
The aliases.Resolver.Exists function currently returns the "clean"
address (with the drop characters and suffixes removed), which is relied
upon in its only caller.
That, however, makes the logic more difficult to follow, hiding some
of the address manipulation behind what should be a read-only check.
So this patch reorganizes that code a little bit, removing the
"cleaning" of the address as part of Exists, and making it explicit when
needed instead.
This patch does not have any user-visible change in behaviour, it is
just internal reorganization.
This is in preparation for further patches which will improve the
handling of some aliases corner cases.
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.
ioutil package was deprecated in Go 1.16, replace all uses with their
respective replacements.
This patch was generated with a combination of `gofmt -r`, `eg`, and
manually (for `ioutil.ReadDir`).
We've accumulated a few linter issues around comments and a couple of
variable names.
While none of them is major, this patch cleans them up so it's easier to
go through the linter output, and we can start being more strict about
it.
This patch implements support for catch-all aliases, where users can add
a `*: destination` alias. Mails sent to unknown users (or other aliases)
will not be rejected, but sent to the indicated destination instead.
Please see https://github.com/albertito/chasquid/issues/23 and
https://github.com/albertito/chasquid/pull/24 for more discussion and
background.
Thanks to Alex Ellwein (aellwein@github) for the alternative patch and
help with testing; and to ThinkChaos (ThinkChaos@github) for help with
testing.
This patch skips the resolution logic if the address is not local.
Today, the resolution logic handles that case transparently, and returns
the original email address, so this should be a no-op.
However, having an explicit early check makes the resolution logic more
robust, and will simplify future patches.
Note this also means that the `alias-resolve` hook is no longer run for
non-local aliases, which should also help simplify their implementation.
The right-hand side addresses of an alias should be normalized, to
maintain the internal invariant that we always deal with normalized
addresses.
Otherwise, strange situations may arise, such as the same domain having
two different domaininfo structures depending on case.
It's more convenient and in line with standard practice to fail RCPT TO if the
user does not exist.
This involves making the server and client aware of aliases, but it doesn't
end up being very convoluted, and simplifies other code.
aliases databases can be very useful, so this patch adds a package to parse
and resolve aliases.
It uses an existing, well known and widely used format for aliases, although
it doesn't necessarily match 100% any existing implementation at the moment.
