Re: Updating to RFC6434 to deal with 8200-style header insertion by IPIP

Brian E Carpenter <brian.e.carpenter@gmail.com> Wed, 08 November 2017 19:15 UTC

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Subject: Re: Updating to RFC6434 to deal with 8200-style header insertion by IPIP
To: Michael Richardson <mcr+ietf@sandelman.ca>
Cc: Tim Chown <Tim.Chown@jisc.ac.uk>, Fernando Gont <fernando@gont.com.ar>, "C. M. Heard" <heard@pobox.com>, 6man WG <ipv6@ietf.org>
References: <CACL_3VETxNVQ+YD5j6ZiWjycQ=ojAuWwB23offNdVKm+S9c_7A@mail.gmail.com> <23308.1509623865@obiwan.sandelman.ca> <CACL_3VFrcombGczXU6Zz=Pk1u2GE=wGG-r+yEefdHai1REqXmQ@mail.gmail.com> <c8911f45-2afc-9d26-c0a8-1017d034a251@gmail.com> <1e62fab6-c434-a474-e53b-e4c7f2d83de0@gont.com.ar> <5cb2b9fd-8546-31fd-d984-d161aef16349@gmail.com> <49F3820E-A9A8-41C4-B6D0-EAEAE0941769@jisc.ac.uk> <52370287-9bd2-1e56-3aa2-f9d1c51455b4@gmail.com> <12447.1510153859@obiwan.sandelman.ca>
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
Message-ID: <c104cb05-ee8f-7958-338b-1e30aa7942d1@gmail.com>
Date: Thu, 9 Nov 2017 08:15:50 +1300
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On 09/11/2017 04:10, Michael Richardson wrote:
> 
> Brian E Carpenter <brian.e.carpenter@gmail.com> wrote:
>     >    Note that it is impossible for a node to distinguish between an
>     > unrecognized extension header and an unrecognized upper layer
> 
> Does "unrecognized" mean unknown to the writer of the code at the time of
> writing, or does it mean a header which the node has no support for?

I think it means unrecognized at run time, regardless of whether it was
known or unknown when the code was written, or configured on or off when
the node was instantiated, or even configured off one microsecond before
the packet arrived. So TBD would be return_icmp(1) in your case.

IMHO.

     Brian

> 
> Or to put it in C, what goes into TBD?
> 
> retry:
>   switch(proto) {
>   case IPPROTO_UDP:
>        udp_rcv();
>        break;
>   case IPPROTO_TCP:
>        tcp_rcv();
>        break;
>   case IPPROTO_AH:
>        if(ipsec_enabled) ipsec_rcv();
>        else TBD;
>   case IPPROTO_HOPOPT:
>        process_hopopt();
>        goto retry;
>   case IPPROTO_MOBILITY_HEADER:
>        skip_hopopt();
>        goto retry;
>   default:
>        return_icmp(1);
>   }
>