Golang implementation of a trace filter for OpenSMTPD

This is a simple implementation based off my opensmtpd-filters-go library.

It logs all events received from opensmtpd to /tmp/filterlog.txt

Example usage in smtpd.conf

filter "trace" proc-exec "/usr/lib/x86_64-linux-gnu/opensmtpd/filter-trace"
listen on "127.0.0.1" port 25 filter trace