UDP checksum broken, -head and releng_8

Daniel Eischen deischen at freebsd.org
Fri Jan 7 11:17:49 UTC 2011

On Fri, 7 Jan 2011, Bjoern A. Zeeb wrote:

> On Fri, 7 Jan 2011, Daniel Eischen wrote:
>> When sending multicast packets to a socket that is _not_
>> bound to the multicast address, this generates bad UDP
>> checksums.  This use to work and was broke sometime between
>> the middle of October and late December as far as I can
>> tell.
> My very best guess would be: r215110

It doesn't look very harmful, but I'll try backing it out.

> Otherwise the usual questions apply though I am almost certain you got
> that right:
> - dumps taken on the receiver side not the sender as

Yes, dumps were taken on both receiving Solaris 10
and FreeBSD hosts.

> - NIC offload capabilities might confuse tcpdump and you might
>  want to turn them off and test as well w/o them

Disabling checksum offloading makes no difference, and the
problem occurs on all interfaces I have tested (sis, bfe,


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