for reporting addresses that cause DSNs to be returned. that just adds noise.
the admin can add/remove/extend addresses through the webadmin.
in the future, we could send reports with a smtp mail from of
"postmaster+<signed-encoded-recipient>@...", and add the reporting recipient
on the suppression list automatically when a DSN comes in on that address, but
for now this will probably do.
- dmarc reports: add a cid to the log line about one run of sending reports, and log line for each report
- in smtpclient, also handle tls errors from the first read after a handshake. we appear to sometimes get tls alerts about bad certificates on the first read.
- for messages to dmarc/tls reporting addresses that we think should/can not be processed as reports, add an X-Mox- header explaining the reason.
- tls reports: send report messages with From address of postmaster at an actually configured domain for the mail host. and only send reports when dkim signing is configured for that domain. the domain is also the submitter domain. the rfc seems to require dkim-signing with an exact match with the message from and submitter.
- for incoming tls reports, in the smtp server, we do allow a dkim-signature domain that is higher-level (up to publicsuffix) of the message from domain. so we are stricter in what we send than what we receive.
we were already accepting, processing and displaying incoming tls reports. now
we start tracking TLS connection and security-policy-related errors for
outgoing message deliveries as well. we send reports once a day, to the
reporting addresses specified in TLSRPT records (rua) of a policy domain. these
reports are about MTA-STS policies and/or DANE policies, and about
STARTTLS-related failures.
sending reports is enabled by default, but can be disabled through setting
NoOutgoingTLSReports in mox.conf.
only at the end of the implementation process came the realization that the
TLSRPT policy domain for DANE (MX) hosts are separate from the TLSRPT policy
for the recipient domain, and that MTA-STS and DANE TLS/policy results are
typically delivered in separate reports. so MX hosts need their own TLSRPT
policies.
config for the per-host TLSRPT policy should be added to mox.conf for existing
installs, in field HostTLSRPT. it is automatically configured by quickstart for
new installs. with a HostTLSRPT config, the "dns records" and "dns check" admin
pages now suggest the per-host TLSRPT record. by creating that record, you're
requesting TLS reports about your MX host.
gathering all the TLS/policy results is somewhat tricky. the tentacles go
throughout the code. the positive result is that the TLS/policy-related code
had to be cleaned up a bit. for example, the smtpclient TLS modes now reflect
reality better, with independent settings about whether PKIX and/or DANE
verification has to be done, and/or whether verification errors have to be
ignored (e.g. for tls-required: no header). also, cached mtasts policies of
mode "none" are now cleaned up once the MTA-STS DNS record goes away.
this also has changes to make the dmarc report sending implementation more
similar to the tls reports implementation.
- factor out code to compose a dmarc report message to the message package
(from dmarcdb for reports), it will be shared soon.
- spread emails with dmarc reports over 45 minutes (it runs hourly), with at
most 5 mins in between reports. to prevent bursts of messages. properly abort
all sending attempts at mox shutdown.
- add use of missing error details in an error path.
- fix dmarc report message subject header by adding missing <>'s around report-id.
- fix dmarc report attachment filename syntax by leaving "unique-id" out.
firstly by using crypto/rand in those cases. and secondly by putting a lock
around the Read (though it isn't used at the moment).
found while working while implementing sending tls reports.
before this change, a message in the rejects folder that was read and marked as
notjunk (e.g. automatically by webmail), could cause a dmarc report to be sent
for another junky message from the domain. we now require positive signals to
be for messages not in the rejects mailbox.
the text/plain body of a dmarc report contains the period, but it was in local
time while claiming to be in utc. make it utc, so we often get nicely rounded
whole 24h utc days.
in smtpserver, we store dmarc evaluations (under the right conditions).
in dmarcdb, we periodically (hourly) send dmarc reports if there are
evaluations. for failed deliveries, we deliver the dsn quietly to a submailbox
of the postmaster mailbox.
this is on by default, but can be disabled in mox.conf.
getting mox to compile required changing code in only a few places where
package "syscall" was used: for accessing file access times and for umask
handling. an open problem is how to start a process as an unprivileged user on
windows. that's why "mox serve" isn't implemented yet. and just finding a way
to implement it now may not be good enough in the near future: we may want to
starting using a more complete privilege separation approach, with a process
handling sensitive tasks (handling private keys, authentication), where we may
want to pass file descriptors between processes. how would that work on
windows?
anyway, getting mox to compile for windows doesn't mean it works properly on
windows. the largest issue: mox would normally open a file, rename or remove
it, and finally close it. this happens during message delivery. that doesn't
work on windows, the rename/remove would fail because the file is still open.
so this commit swaps many "remove" and "close" calls. renames are a longer
story: message delivery had two ways to deliver: with "consuming" the
(temporary) message file (which would rename it to its final destination), and
without consuming (by hardlinking the file, falling back to copying). the last
delivery to a recipient of a message (and the only one in the common case of a
single recipient) would consume the message, and the earlier recipients would
not. during delivery, the already open message file was used, to parse the
message. we still want to use that open message file, and the caller now stays
responsible for closing it, but we no longer try to rename (consume) the file.
we always hardlink (or copy) during delivery (this works on windows), and the
caller is responsible for closing and removing (in that order) the original
temporary file. this does cost one syscall more. but it makes the delivery code
(responsibilities) a bit simpler.
there is one more obvious issue: the file system path separator. mox already
used the "filepath" package to join paths in many places, but not everywhere.
and it still used strings with slashes for local file access. with this commit,
the code now uses filepath.FromSlash for path strings with slashes, uses
"filepath" in a few more places where it previously didn't. also switches from
"filepath" to regular "path" package when handling mailbox names in a few
places, because those always use forward slashes, regardless of local file
system conventions. windows can handle forward slashes when opening files, so
test code that passes path strings with forward slashes straight to go stdlib
file i/o functions are left unchanged to reduce code churn. the regular
non-test code, or test code that uses path strings in places other than
standard i/o functions, does have the paths converted for consistent paths
(otherwise we would end up with paths with mixed forward/backward slashes in
log messages).
windows cannot dup a listening socket. for "mox localserve", it isn't
important, and we can work around the issue. the current approach for "mox
serve" (forking a process and passing file descriptors of listening sockets on
"privileged" ports) won't work on windows. perhaps it isn't needed on windows,
and any user can listen on "privileged" ports? that would be welcome.
on windows, os.Open cannot open a directory, so we cannot call Sync on it after
message delivery. a cursory internet search indicates that directories cannot
be synced on windows. the story is probably much more nuanced than that, with
long deep technical details/discussions/disagreement/confusion, like on unix.
for "mox localserve" we can get away with making syncdir a no-op.
the warnings that remained were either unused code that i wanted to use in the
future, or other type's of todo's. i've been mentally ignoring them, assuming i
would get back to them soon enough to fix them. but that hasn't happened yet,
and it's better to have a clean list with only actual isses.
the backup command will make consistent snapshots of all the database files. i
had been copying the db files before, and it usually works. but if the file is
modified during the backup, it is inconsistent and is likely to generate errors
when reading (can be at any moment in the future, when reading some db page).
"mox backup" opens the database file and writes out a copy in a transaction.
it also duplicates the message files.
before doing a restore, you could run "mox verifydata" on the to-be-restored
"data" directory. it check the database files, and compares the message files
with the database.
the new "gentestdata" subcommand generates a basic "data" directory, with a
queue and a few accounts. we will use it in the future along with "verifydata"
to test upgrades from old version to the latest version. both when going to the
next version, and when skipping several versions. the script test-upgrades.sh
executes these tests and doesn't do anything at the moment, because no releases
have this subcommand yet.
inspired by a failed upgrade attempt of a pre-release version.
