Re: [IPv6] New Draft - ICMPv6 Loopback

On 6/7/23 08:06, Erik Kline wrote:
> Poking around the Linux kernel source, my reading of net/ipv6/icmp.c's
> icmpv6_rcv() is that it checks the type byte before dispatching to
> icmpv6_echo_reply(), and inside icmpv6_echo_reply() I'm not seeing any
> checking of the code byte, so I'd assume (without testing) that it
> just constructs a normal echo reply.  I also suspect that it just
> copies the incoming code value into the reply.
> 
> The only differentiation I see being made is between echo request
> (4443) and extended echo request (8335).
> 
> Should be easy enough to test (after I get a few other things done).

+1 ... tested and confirmed (pcap attached, code 0 for packets 1-2, code 
1 for packets 3-4).

Cheers,
Justin

> On Tue, Jun 6, 2023 at 9:30 PM Tal Mizrahi <[email protected]> wrote:
>>
>> Bob, Eric,
>>
>> Thanks for the feedback.
>> Defining a new code for ICMPv6 Echo rather than defining a new type
>> may be the right way to go.
>> Our main concern with this is that RFC 4443 defines what to do with an
>> unknown type, but does not define what to do with an unknown code. It
>> is not clear what existing implementations do when receiving an Echo
>> Request with an unknown code. That is why the current draft calls for
>> a new type. However, we are open to more feedback about this, and it
>> may end up being just a new code.
>>
>> Cheers,
>> Tal.
>>
>> On Tue, Jun 6, 2023 at 8:33 PM Eric Vyncke (evyncke) <[email protected]> wrote:
>>>
>>> Without any hat, I agree with Bob.
>>>
>>> This I-D should eventually go to 6MAN WG though (with my AD hat)
>>>
>>> -éric
>>>
>>> On 06/06/2023, 08:34, "Int-area on behalf of Bob Hinden" <[email protected] <mailto:[email protected]> on behalf of [email protected] <mailto:[email protected]>> wrote:
>>>
>>>
>>> Tal,
>>>
>>>
>>> I did a quick read of your draft.
>>>
>>>
>>> As noted in the draft this seems to be very similar to ICMPv6 Echo/Echo Reply. The change is to include the request packet in the response, not just the payload.
>>>
>>>
>>> While I don’t have any real opinion on the need for this, I do think it would be a lot simpler if the draft just defined a new Code field value for Echo Request/Reply that specified this behavior. Currently the Code field is set to zero, another value could specify this behavior.
>>>
>>>
>>> Deployment might be easier as I suspect ICMPv6 types other than the current definitions will be filtered in many places.
>>>
>>>
>>> Bob
>>>
>>>
>>>
>>>
>>>
>>>
>>>> On Jun 6, 2023, at 4:54 AM, Tal Mizrahi <[email protected] <mailto:[email protected]>> wrote:
>>>>
>>>> Hi,
>>>>
>>>> New draft: https://datatracker.ietf.org/doc/draft-mcb-intarea-icmpv6-loopback/ <https://datatracker.ietf.org/doc/draft-mcb-intarea-icmpv6-loopback/>
>>>>
>>>> We have posted a new draft that proposes two new ICMPv6 message types:
>>>> Loopback Request and Reply.
>>>> ICMPv6 Loopback is very similar to Echo, except that after a Loopback
>>>> Request is sent, its corresponding Reply includes as much of the IPv6
>>>> Loopback Request packet as possible, including the IPv6 header and
>>>> IPv6 extension headers and options if they are present.
>>>>
>>>> We believe that ICMPv6 Loopback can be very useful for returning IPv6
>>>> options that were included in Request packet back to the sender,
>>>> including for example sending IOAM [RFC 9197] data from the Request
>>>> back to the sender, sending the SRH [RFC 8754] of the Request back to
>>>> the sender, as well as for in-progress / future protocols such as
>>>> draft-filsfils-spring-path-tracing and draft-kumar-ippm-ifa.
>>>>
>>>> We would be happy for feedback, as well as suggestions about whether
>>>> the INT-AREA WG is the right place to discuss this draft.
>>>>
>>>> Cheers,
>>>> Tal.
>>>>
>>>> _______________________________________________
>>>> Int-area mailing list
>>>> [email protected] <mailto:[email protected]>
>>>> https://www.ietf.org/mailman/listinfo/int-area <https://www.ietf.org/mailman/listinfo/int-area>
>>>
>>>
>>>
>>>
>>>
>>
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