Date: Tue, 28 Aug 2007 08:59:29 -0500 From: "Christian S.J. Peron" <csjp@FreeBSD.org> To: "Bruce M. Simpson" <bms@FreeBSD.org> Cc: FreeBSD Current <current@freebsd.org>, Andrew Thompson <thompsa@FreeBSD.org> Subject: Re: multicast packets from bpf Message-ID: <20070828135929.GA2305@sub.vaned.net> In-Reply-To: <46D3C9F3.2010802@FreeBSD.org> References: <20070828040026.GB42201@heff.fud.org.nz> <46D3C9F3.2010802@FreeBSD.org>
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On Tue, Aug 28, 2007 at 08:08:35AM +0100, Bruce M. Simpson wrote: [..] > > I favour the first approach, however, it may make more sense to put the > logic into bpf_movein() as it already builds a sockaddr based on the header > data provided to bpf during a write. > > For the first patch: I previously fixed tapwrite() to check injected frames > in the same way, as this was causing a problem with my own use of > if_bridge. There is no way that I see for bpf to be able to tell if a frame > is link-layer multicast or not, and checking at that layer does introduce a > little pollution. Ethernet is the most common case so it could be argued > that's OK, as we have ethernet-specific fields in struct mbuf now. Your > change is the parallel change in the bpfwrite path to what I have in the > tapwrite path. > I think that tap(4) is a bit different since the only kind of frames it handles are Ethernet. This is not the case for bpf(4). I wonder if it makes sense to add this check into ether_output()? IIRC bpf will call the network interface's output routine, in the Ethernet/bridge case it should be ether_output(). Thoughts? -- Christian S.J. Peron csjp@FreeBSD.ORG FreeBSD Committer
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