Re: [Qemu-devel] [PULL 1/1] slirp: fix ICMP handling on macOS hosts

[Andrew Oates]

On Wed, Aug 1, 2018 at 6:10 AM Peter Maydell <address@hidden>
wrote:

> On 1 August 2018 at 00:25, Andrew Oates <address@hidden> wrote:
> > Both CONFIG_BSD and not-CONFIG_LINUX work on macOS.  I unfortunately
> don't
> > have access to any other BSDs to test them, though.
>
> Is there an easy way to test it? The QEMU makefiles have some
> runes for setting up a BSD VM...
>

Ok, it turns out that SOCK_DGRAM+IPPROTO_ICMP isn't actually supported on
FreeBSD---tested in qemu (thanks for the tip!).

I didn't actually boot up NetBSD or OpenBSD, but poking around the kernel
source I found for them it appears they have the same restriction:
https://github.com/freebsd/freebsd/blob/master/sys/netinet/in_proto.c
https://github.com/openbsd/src/blob/master/sys/netinet/in_proto.c
http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/netinet/in_proto.c?rev=1.128&content-type=text/x-cvsweb-markup

(search for SOCK_DGRAM and IPPROTO_ICMP in the above).

So I don't think ICMP via SLIRP would work at all in the other BSDs,
meaning this patch is a no-op for them either way.  If we _were_ to make
SLIRP+ICMP work in *BSD, we'd presumably want to do it with a
SOCK_RAW+IPPROTO_ICMP socket (which would require special permissions to
create), which would mean an included IP header---so I think that #ifdef
CONFIG_BSD here is defensible.

I did some poking for Solaris and Haiku and didn't find much, though it
looks like the version of ping included w/ Haiku uses SOCK_RAW rather than
SOCK_DGRAM, so it may be in the same boat as non-OSX-BSDs (
https://github.com/haiku/haiku/blob/master/src/bin/network/ping/ping.c#L205
).

~Andrew


>
> thanks
> -- PMM
>