Date: Fri, 16 Apr 2010 11:21:06 +0100 From: Bruce Simpson <bms@incunabulum.net> To: Alexander Leidinger <Alexander@Leidinger.net> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r206452 - head/sys/netinet Message-ID: <4BC83A12.2080700@incunabulum.net> In-Reply-To: <20100416102318.16752py80bkf418g@webmail.leidinger.net> References: <201004101205.o3AC5VGp074266@svn.freebsd.org> <4BC7486C.9010804@incunabulum.net> <20100416102318.16752py80bkf418g@webmail.leidinger.net>
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On 04/16/10 09:23, Alexander Leidinger wrote: > >> IP multicast group membership is always scoped to physical links [1]. >> The 4.4BSD API originally used the "primary IP address" to identify >> each link. Unfortunately this is not a persistent identifier, >> especially so in the use-case which had problems. > > > Is/was this the reason why multicast does not work in jails? The above point is totally unrelated to jail. I think the problem with jail is the fact that to receive multicast, sockets normally need to be bound to INADDR_ANY. Obviously, jail changes socket behaviour in interesting ways. This may require refactoring udp_input() considerably. We use the 4.4BSD legacy LIST_FOREACH() loop to deliver, rather than using a fan-in map (which is the Windows/Solaris approach). Linux also has 4.4BSD semantics, but can work around this by examining the SO_BINDTODEVICE option in the same path.
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