Re: "Wire" definitions and __packed

[Eduardo Horvath <eeh%NetBSD.org@localhost>]

On Wed, 5 Oct 2016, Roy Marples wrote:

> On 04/10/2016 23:06, Joerg Sonnenberger wrote:
> > I'd like to addressing this by cutting down on the first set. For this
> > purpose, I want to replace many of the __packed attributes in the
> > current network headers with CTASSERT of the proper size, especially for
> > those structs that are clearly not wire definitions by themselve.
> 
> I tested the following structs without packed with the latest dhcpcd
> trunk (not yet in NetBSD).
> 
> ip
> udphdr
> arphdr
> in_addr
> nd_router_advert
> nd_opt_hdr
> nd_opt_prefix_info
> nd_opt_mtu
> nd_opt_rdnss
> nd_opt_dnssl
> 
> Works fine so far.

What platforms did you test it on?

I recommend trying it on sparc64.  That's one of the worst cases, being 
big-endian 64-bit with alignment constraints.  And I recall some ABI (was 
it ARM?) has strange alignment restrictions on byte values.

Eduardo