I can see someone wanting to know the raw physical connection
info at some point, regardless of the adjusted xclient values,
or in the future, the proxy protocol adjusted values.
To facilitate this we need to feed the `AppState` down through
the Router more generally, and expand it to grab a copy of the
http listener parameters.
closes: https://github.com/KumoCorp/kumomta/issues/417
This enables configuring mTLS support in the listener.
Adjust TLS client tests to use this on the sink side and verify
that mTLS works for both inbound and outbound SMTP.
refs: #100
refs: #391
This commit extracts the TLS version, cipher and subject name from
the TLS state and captures it:
* In the trace headers
* In the connection metadata
* In the Reception log record
In order to capture the info in trace headers, this commit will
now change the reception protocol to ESMTPS (for SSL) or ESMTPSA (for
authenticated SSL), and emit the version and cipher information as
a comment like: `with ESMTPS (TLSv1_3:TLS13_AES_256_GCM_SHA384)`.
closes: #100
TL;DR: you can easily halve your system performance by logging headers
vs. logging meta.
This is one of those things that is easy to overlook or forget,
but: whenever you need to operate on the message data, rather
than its metadata, the aggregate cost is high.
In this case, we were recently troubleshooting a system where
the CPU was bogged down and we traced it to the logging configuration: a
number of message headers were being logged in a configuration that
made heavy use of throttles and limits in its traffic shaping, and
thus had a large number of Delayed and TransientFailure events being
written to the logs.
When logging headers, each one of those events requires loading
the message from the spool and parsing out the headers. When the
average message size is ~100KB this imposes a notable overhead
on the CPU and IO utilization of the system.
What we recommend instead of logging headers directly is capturing
the information that you want to log into the message metadata
at the time that the message is received.
The message meta is usually already loaded, but is also typically
much smaller and easier to decode than the full message content
in the cases where it is not loaded.
As a result, it is much cheaper to log meta than to log headers.
This commit adds some warnings and cross links to help folks
be aware of this, and to generally navigate related meta and logging
topics more easily via tags.
Wez Furlong
Harsh Jha
Mike Hillyer