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Re: libCurl does not send data using multi interface on high latency connections

From: Nicolás Bagnasco via curl-library <>
Date: Wed, 12 Sep 2018 20:13:45 -0300

> If you try the curl command line tool on the same URL, I presume it works?

Yes, in that case the command line works as expected. The same happens
(work as expected) when using libCurl without boost::asio as in

> I hope your app isn't based purely on that example but on your fine
> knowledge of boost::asio and how to use libcurl with that.

Sadly I am the maintainer of an old app which is not mine, and some
parts of the networking code that handles http connections uses the
same code from the asiohiper example.

> In that situation libcurl should've already told your app that it wants to
> wait on that socket to become writable and when it does (when it can send the
> request over it), you should've called libcurl telling it about that fact. Did
> that happen or not?

I'm not sure about what you are trying to tell me here but I assume
that you are referring to CURLMOPT_SOCKETFUNCTION.
If that's the case, I think I need to understand what's going on with
the CURL_POLL_IN and CURL_POLL_OUT events because it seems that it's
handled in the example, I don't know however if it's handled the way
it should.

> Right, but since we *know* that the example isn't correct, it could also just
> be the example app not using libcurl correctly.

I agree, it can be an improper use of the library, but I can not
figure out what it is.

> I personally don't know anything about boost::asio so I'm not a suitable
> person to fix the example code nor to debug a boost::asio-using application.

My knowledge of boost::asio and libCurl is pretty limited too.
I will try to understand what's going on and will update this thread
if I find something. Thank you for your response.

Nicolas Bagnasco.
Received on 2018-09-13