Bugs item #3415046, was opened at 2011-09-28 16:58
Message generated for change (Tracker Item Submitted) made by phdems
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Category: name resolving/DNS
Group: wrong behaviour
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Philippe Demange (phdems)
Assigned to: Daniel Stenberg (bagder)
Summary: Resolution name hangs longer than specified timeout

Initial Comment:
Hello world,

I am experiencing a problem with the name resolution, either with c-ares enabled or not. In both cases, if the resolution is not possible (for example by setting a wrong DNS in /etc/resolv.conf or by removing the ethernet cable), libcurl hangs for several seconds before returning, although a timeout is set to 1 second.

Precision: As I am working on UNIX system, I've set the CURLOPT_NOSIGNAL option as recommended, thus avoiding a segfault.

Here is what I observe:
1. c-ares enabled + curl_easy_perform: OK (timeout of 1 second)
2. c-ares enabled + curl_multi_perform: hangs during almost 60 seconds (callback ares_query_completed_cb is not called during this time)
3. c-ares disabled + curl_easy_perform: hangs during 20 seconds (blocked by getaddrinfo in Curl_getaddrinfo_ex)
4. c-ares disabled +curl_multi_perform: hangs during 20 seconds (blocked by getaddrinfo in Curl_getaddrinfo_ex)

Source code is attached (based on mutli-single.c example sample code from curl.haxx.se), as is config.log file (generated at libcurl's build).

Any idea, suggestion or help will be very much appreciated :) Thanks in advance.

Best Regards.
Philippe.

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Received on 2011-09-28