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Re: Phantom socket with threaded resolver

From: Daniel Stenberg via curl-library <curl-library_at_cool.haxx.se>
Date: Fri, 9 Oct 2020 23:13:04 +0200 (CEST)

On Fri, 9 Oct 2020, Sean Miller via curl-library wrote:

(This might be a varation of this issue:
https://github.com/curl/curl/issues/5747 )

> In response, libcurl appears to create a socket for DNS resolution without
> asking for it via CURLOPT_OPENSOCKETFUNCTION.

That's correct, because it isn't a regular socket. It's a socketpair.
CURLMOPT_SOCKETFUNCTION should get told about it though. Doesn't it?

> Is this behavior intentional? Is there a recommended way to either force
> libcurl to ask for the socket, or else avoid telling me about it? Where did
> I go wrong?

Yes and no. It is a socketpair used to signal when the resolve is complete. It
isn't a plain old socket so CURLOPT_OPENSOCKETFUNCTION cannot be used for it.

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Received on 2020-10-09