dscp set/get

[Franco Fichtner]

> On 06 Oct 2016, at 3:32 PM, Kristof Provost <kp at freebsd.org> wrote:
> 
> On 6 Oct 2016, at 15:01, Mark Martinec wrote:
>> Just adding recognition to a parser for a couple of DSCP constants
>> to be mapped to TOS is not the solution. Keep in mind that DSCP
>> is a 6-bit field, and TOS is an 8-bit field. The remaining two bits
>> are used for ECN (Explicit Congestion Notification).
>> 
>> Setting TOS field with the intention of changing DSCP
>> clobbers ECN bits.  Pf needs a proper support for DSCP,
>> currently it is unusable for this purpose in FreeBSD
>> (one can use the PF from OpenBSD).
>> 
> 
> Hmm, that’s a good point.

That's two one-liners, one for set and one for match?

Surprised that this wasn't included already.

> OpenBSD seem to just always preserve the ECN bits (so there’s no dscp keyword).
> Perhaps we should do the same.

I have a full patch for review tonight.


Cheers,
Franco