[Twisted-Python] Patch to support DNS updates

[Jeff Silver]

> (the feature does sound nice,

Thank you.

> ... altough lack of authentication makes using it pretty
> pointless IMHO),

For most situations, I agree with you. It so happens that updates without
authentication are fine for the environment I'm setting up. My focus was on
implementing the functionality that I need, although of course I don't want to
break anything, or prevent anyone else extending this further. There's no
reason why authentication (and the other missing bits) shouldn't be added. But
I thought I'd got to a stable enough point to submit.

As implemented in the patch, updates are permitted on all zones. In retrospect,
and given your comment, I think I was wrong. I should allow updates only in
zones specified using my new --*zonefile options. That way there is no change
of behaviour whatever for people continuing to use the original --*zone
options. I certainly don't want to open up security holes in existing
installations.

I shall fix this before submitting a new patch to the bug list (as requested by
itamar).

> this is just unacceptable.
> 
> If an exception is raised, the app crashes, or the machine loses power
> between those two renames, your original zone file has been renamed
> and your DNS server won't start.

Point taken. I'll do a single os.rename() as you suggest.


> Also, nice y2.043k trap there, I don't think many have been able to
> write ones targeting that exact date.

Hmmm.. Not sure what you mean. If I read the Python 2.4 documentation
correctly, these numbers will be handled as long integers. The subtraction just
converts the 4-digit year at the start to 'years since 2000'. Am I missing
something? If so, please say, and I can handle the year separately.

Thanks for the comments.
Jeff