haproxy ssl support

Even though it seems dovecot (using 2.2.33.1) supports haproxy's send-proxy-v2, it seems to lack send-proxy-v2-ssl (which also sends client's ssl state). It would be a nice feature for the backend server to identify clients so one wouldn't have to use disable_plaintext_auth on a production environment.

--- haproxy.cfg frontend pop3 bind [::]:110 v4v6 bind [::]:995 v4v6 ssl crt /etc/pki/tls/private/haproxy.pem mode tcp default_backend pop3 backend pop3 mode tcp balance leastconn stick store-request src stick-table type ip size 200k expire 30m timeout connect 5000 timeout server 50000 server proxy1 [2001:db8::11]:10110 send-proxy-v2-ssl server proxy2 [2001:db8::22]:10110 send-proxy-v2-ssl

--- dovecot.conf haproxy_trusted_networks = [2001:db8::]/64 service pop3-login { inet_listener pop3_haproxy { port = 10110 haproxy = yes } }

It would also be nice if haproxy would support STARTTLS offloading but that's a subject for a different mailing list ;)

-- BR, Rok