kern/179901: [netinet] [patch] Multicast SO_REUSEADDR handled incorrectly

[Bernd Walter]

On Fri, Jun 28, 2013 at 12:15:14PM +0200, Bernd Walter wrote:
> On Mon, Jun 24, 2013 at 03:59:24AM +0000, linimon at freebsd.org wrote:
> > Old Synopsis: [patch] Multicast SO_REUSEADDR handled incorrectly
> > New Synopsis: [netinet] [patch] Multicast SO_REUSEADDR handled incorrectly
> > 
> > Responsible-Changed-From-To: freebsd-bugs->freebsd-net
> > Responsible-Changed-By: linimon
> > Responsible-Changed-When: Mon Jun 24 03:59:05 UTC 2013
> > Responsible-Changed-Why: 
> > Over to maintainer(s).
> > 
> > http://www.freebsd.org/cgi/query-pr.cgi?pr=179901
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> 
> I don't know if this is related or a different bug, but the same
> mentioned commits are suspicious for us.
> We had been running with our own IPv6 software into the same REUSEADDR
> problem and changed to REUSEPORT as this is how it is done in mcastread
> from mcast-tools port.
> Don't know where we originally got the REUSEADDR from, probably a Stevens
> book.
> So far binding works with this change in our software.
> However we only receive packets from network and not packets from
> the host itself.
> We use multicast to notify multiple processes on multiple machines,
> including the machine itself.
> To reproduce:
>  - use two hosts
>  - start mcastread on each of them on an interface with shared LAN
>  - send via mcastsend on one host
>  - packets are received on the other host, but not with the mcastread
>    on the same host

It is unrelated, but I have found the cause for it and filed kern/180065
together with a working patch.
The reason is that the packets have no valid checksums when processed
in ip6_input because of delayed checksum changes.

-- 
B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.