Re: [Monotone-devel] netsync flag day justifies bumping version number to 1.0

[Timothy Brownawell]

On Wed, 2009-08-26 at 09:42 -0600, Derek Scherger wrote:
> 
> 
> On Wed, Aug 26, 2009 at 7:44 AM, <address@hidden> wrote:
>         
>         > It would be nice if the 0.45 server could deal gracefully
>         with older
>         > clients, and vice-versa, but it's not a requirement.
>         
>         
>         And there seems to be some question whether it's reliably
>         possible to
>         recognise older clients with the protocol they understand at
>         present.
> 
> At a glance, I concur with Tim that there's no space in the initial
> packet (other than the nonce) for a new server to hint to a client
> that it speaks a newer protocol.

Actually, I've been looking at the code more and it *is* possible.

Since early 2006, the version field on usher_cmd packets is completely
ignored. And they can be inserted anywhere, the normal/intended use is
for them to be sent by a proxy before connecting to the real server.

So the thing would be for the server to send an usher_cmd packet before
start_cmd, using its current netsync version. The current client will
then ignore that version and reply with a packet that happens to include
its version, which the server than then use for everything else
including the start_cmd.


-- 
Timothy

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