draft-miller-ssh-agent-02: extensions and success messages

[Alex Wilson]

On 06/04/18 05:19, Damien Miller wrote:
> On Thu, 5 Apr 2018, Alex Wilson wrote
>>
>> The format of that message doesn't change though -- it's always a single
>> byte (so you don't need that information in the function that actually
>> parses the message). With this proposal that is no longer the case. I
>> mean, maybe it's a pointless concern and things are fine as proposed. I
>> wrote my client implementation to not have any of that state there for
>> parsing messages to make it easier to test and fuzz. I know other
>> implmentations don't necessarily do the same thing.
> 
> ok, so what behaviour would you prefer?
> 
> AFAIK the only way to be completely unambiguous would be to echo the
> full extension name in the reply, which seems unnecessarily verbose.
> 
I would be fine with echoing the full name of the extension, personally.
An extra 20-30 bytes or so over AF_UNIX is not far off being free
performance-wise on modern systems.

If you think that's a non-starter though, then maybe a next-best option
could be an "extension reply" message? That way there's no ambiguity
about the structure of the "success" message at least.

As I said, though, do feel free to tell me you think it's not worth the
effort and I should stop whinging. I'll still use the extension
mechanism as proposed. :)