Re: SFTP v6?

[Joseph Galbraith <galb-list%vandyke.com@localhost>]

Niels Möller wrote:
> Joseph Galbraith <galb-list%vandyke.com@localhost> writes:
> > Niels Möller wrote:
>
> > > > 4. When a version negotiation failure occurs, both sides
> > > >   know why, because they both have the same information.
>
> > I tried to change the version negotiation back when
> > I first started editing sftp so that the server sent
> > back it's version (V_S rather than V_U)... which
> > at least gives the server something valid to send
> > when version negation fails, but we had to back
> > it out because of backwards compatibility.
>
> One simple idea: In this failure case, server version 6, client
> version 4 (say), is there any good reason the server can't send
> version 6 in its SSH_FXP_VERSION, before disconnecting? That would
> give the client at least some clue. It could reasonably interprete
> this response as "This server doesn't seem to support versions below
> 6", and tell that to the user.

Yes; unfortunately, it is hard to say waht a version 4 client
would do with that, since it isn't legal in the protocol
v4 protocol... if we'd spec'd it that way for 4 it could
work :-)

We could make the change for v6... and the implementation
would have to decide whether to take the risk that a v4
implemenation would behave better with an invalid version
packet or behave better with a silent channel close.

I think I'd prefer to solve the whole ball of wax at
one go... this is an area where we've been bandaging
the protocol for a while for backwards compatibilities
sake.

I'd like to just bite the bullet and get it over with.

- Joseph