Re: [Anima-bootstrap] Anima bootstrap: discover protocol multicast notes

Brian E Carpenter <brian.e.carpenter@gmail.com> Sun, 12 February 2017 22:20 UTC

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To: Michael Richardson <mcr+ietf@sandelman.ca>
References: <20170117171732.GA14606@faui40p.informatik.uni-erlangen.de> <20170117172824.GB14606@faui40p.informatik.uni-erlangen.de> <c5daca2c-2c33-ee33-3415-7ce01a49715f@gmail.com> <12728.1486936969@obiwan.sandelman.ca>
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
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Date: Mon, 13 Feb 2017 11:20:44 +1300
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Subject: Re: [Anima-bootstrap] Anima bootstrap: discover protocol multicast notes
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On 13/02/2017 11:02, Michael Richardson wrote:
> 
> Brian E Carpenter <brian.e.carpenter@gmail.com> wrote:
>     >> This information is typically ignored in existing network protocol
>     >> stacks
>     >> and is also typically unavailable on the socket-API. This IMHO makes
>     >> it highly beneficial to
>     >> use a very lightweight protocol (like the subset of GRASP dedicate to
>     >> this) that can specifically
>     >> be implemented to do this security check.
> 
>     > Presumably you have to use a raw socket. I don't see any other way to get the
>     > destination address out of the packet.
> 
> With recvmsg(), you can can as for IPV6_RECVPKTINFO in the auxiliary
> messages in IPV6_PKTINFO.  You get the destination IPv6 address as well as
> the ifindex.  (ifindex is pretty essential if you are receiving multicast messages)

Yes, for multicast I now see that I do pick up the destination address and ifindex
from recvfrom(). I haven't needed to look at that code for many months. For TCP
I seem to pick it up from accept().

     Brian