Re: [task #4633] GPG-Signed Commits

[Jim Hyslop]

Derek Price wrote:
> One thought is to combine my original idea with #3 above, so that the
> server hands out sequence-ids with every connection but decrements the
> max-sequence-id counter when a client disconnects without using the id
> for a commit.  This would require a little bit of complex code including
> locks, DBM use, and additional cleanup handlers, but should be doable
> and fairly fast on the server end.

One fly in this ointment is how to handle overlapping operations, e.g.:

client A connects
server issues sequence-id 1
client B connects
server issues sequence-id 2
client A starts a read-only op
client B starts commit
client B ends commit
client A ends its operation

Sequence ID 1 is unused, but 2 is used, so the server can't decrement 
the counter. It wouldn't be too difficult to mount a DoS attack on this 
scenario.

I suppose there probably won't be more than a few (dozen? hundred?) 
users accessing the repository simultaneously, so it shouldn't be _too_ 
difficult to keep track of unused ids. And, of course, this means the 
numbers won't necessarily be sequential.

Another possibility would be to add a new request/response command to 
the protocol, so a client explicitly requests a commit id. OTOH, this 
is, if anything, even more vulnerable to a DoS attack.

How does CVSNT generate its commit-id?

<sigh> Why can't people just play nicely together? :=)

--
Jim