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How Handle DNS timeout cases from Application

From: Jayashankara DM via curl-library <curl-library_at_cool.haxx.se>
Date: Mon, 8 Jun 2020 09:32:18 +0530

Hi,

We are facing an application crash issue when DNS resolution is not
successful.

Background:
We have a multi-threaded application, In which only one thread uses the
curl to make connections to our server. Remaining threads are not using
curl.

Curl version: curl-7.63.0
OS : Linux

When DNS resolution is not possible for some reason (like DNS server is
down or can be any other reason) our application is crashing.

Can please let me know how to handle this case in our application, We tried
setting CURLOPT_NOSIGNAL = 1 which solves this problem, But leads to some
other issues like not handling dynamic server down issues.

Please answer below questions wrt this issue.

1>

Can you please suggest how to handle the DNS resolution issues ( May be
timeout or DNS server is wrong or DNS server is not configured ) from
application point of view to avoid the crash ?

2>

Please also let me know "curl-7.63.0" is by default support "threaded
resolver" or from which curl version onward "threaded resolver " is
supported by default ?

3>

One basic question: We have a board with curl 7.49.1 and Client application
is built with curl-7.63.0 (libcurl.so dynamic library) . When we run this
application on board will it use curl version 7.49.1 or curl-7.63.0 ?

Thanks,
Jay

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Received on 2020-06-08