[exim-dev] DSCP for inbound connections

I'm thinking that the best way to have DSCP set for the packets outbound
from Exim as a server, when a client connects, is to have a
"control = dscp/$value"
option which can be set in the acl_smtp_connect ACL.

Thoughts? Does this seem sane?

In discussion with a user who wants/needs DSCP, am looks like there's a
need to be able to reference the DSCP value for inbound connections, so
something like $received_initial_dscp as a variable.

The _initial_ because theoretically I believe the DSCP/TOS/TCLASS can
change during a connection, but I don't know if we want to support that
in an ACL other than the initial one.

Although, I suppose if a user authenticates, we might want to let the
admin put them into a better traffic class, so perhaps it *should* be
adjustable from any SMTP ACL ...

-Phil