Domains in addresses had very lax validation, which allowed them to
include characters like "/".
That could be exploited to trigger a daemon panic: a MAIL FROM
"x@evil/foo" could be accepted and, on failed delivery, a DSN queued.
Attempting to deliver the DSN would cause an MTA-STS cache lookup, which
would panic because the domain includes a "/" and crash the server.
Because the DSN would be queued, the server would crash again on
restarts, and only self-recover after give_up_send_after (20h by
default).
To fix this, we now explicitly validate the domain when normalizing it,
make MTA-STS cache not panic on invalid domains, and also make the SMTP
courier fail permanently on invalid domains.
Thanks to John JEAN <john@wargan.com> for finding and reporting this
problem. The detailed report can be found in
https://johnjean.io/advisories/chasquid-unauthenticated-remote-dos/.
This is a follow-up on the `go fix` run in commit
0210c5fd92.
That commit recorded the automated updates.
This one applies further simplifications that are mechanical and do not
involve logic changes, but are outside of what `go fix` did.
It also removes some now-obsolete comments and statements.
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 updates the auto-generated code to match the latest tooling
versions.
In particular, the protobufs are regenerated, and the new version no
longer supports unkeyed literals, so some minor changes are needed.
Other than that, the cipher list is extended with the latest ciphers.
This patch adds some tooling and scripts to generate test coverage
information.
Unfortunately, this involves some hacks as Go does not have support for
generating coverage-enabled binaries, or merging coverage reports; but
overall it's not very intrusive.
If there's an alias to forward email to a non-local domain, using the original
From is problematic, as we may not be an authorized sender for it.
Some MTAs (like Exim) will do it anyway, others (like gmail) will construct a
special address based on the original address.
This patch implements the latter approach, which is safer and allows the
receiver to properly enforce SPF.
We construct a (hopefully) reasonable From based on the local user, and
embedding the original From (but transformed for IDNA, as the receiver may not
support SMTPUTF8).
When we permanently failed to deliver to one or more recipients, send delivery
status notifications back to the sender.
To do this, we need to extend a couple of internal structures, to keep track
of the original destinations (so we can include them in the message, for
reference), and the hostname we're identifying ourselves as (this is arguable
but we're going with it for now, may change later).
This patch makes the queue read and write items to disk.
It uses protobuf for serialization. We serialize to text format to make
manual troubleshooting easier, as the performance difference is not very
relevant for us.
Alberto Bertogli