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Re: asynch name resolves

From: Daniel Stenberg <>
Date: Sun, 20 Jul 2003 01:01:58 +0200 (CEST)

On Wed, 16 Jul 2003 wrote:

> The fact that it looks up names synchronously pretty much requires that you
> use multiple threads for "good performance".

Possibly, yes.

> Have you looked at "ares"?

Nope, I have not.

> The license is MIT which I believe makes it compatible with Curl.

It would indeed. We could even incorporate it into our source tree, should we
consider that a good thing.

> It seems to support exactly the interface that Curl would like to have.

This looks very interesting indeed.

> As far as I can tell, there are only two problems with this library. The
> first is the lack of IPv6 support. I have no idea how serious a problem
> this would be. Is there a new DNS protocol or are there just minor
> differences that you are able to deal with?

I'd call them "minor differences" when it comes to the actual DNS protocol "on
the wire" (and the new API for actually requesting IPv6 resolves).

> The second is that it is UNIX based. In the last couple of days, we ported
> it to windows and the example programs are working (but we haven't tested it
> all that extensively yet).

Ah, cool. Then I guess the only problem is the lack of IPv6 support, and we
can surely survive not having that in a first step towards true and proper
asynch resolves!

I bet that we have a different problem as well, that you didn't mention here.
This library probably only looks up names from DNS, but gethostbyname() and
similar calls in the operating systems use more mechanisms than just DNS to
find names and we need to support those as well... And that might take some
platform dependent stuff. Or does ares take this into account already?

> If Curl is interested in looking into this library, I'd be glad to make a
> patch available as well as a VC++ project for the windows version of the
> library.

I think this sounds and seems highly interesting. I'll be back for real from
my vacation this upcoming week and I hope to be able to get some time to dig
into ares a bit deeper then.

I'll appreciate all help, patches and things you can provide!

 Daniel Stenberg -- curl: been grokking URLs since 1998
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Received on 2003-07-20