getaddrinfo_with_timeout function incorrectly treats EAI_ALLDONE (-103) from gai_suspend as an error

[kgokalp]

In the getaddrinfo_with_timeout function, gai_suspend may return EAI_ALLDONE (-103) in some cases. According to the glibc manual, EAI_ALLDONE indicates that all requests are already complete. This is not an error condition, it simply means there is nothing left to wait for, and the caller should check request results using gai_error(). Currently, the code treats EAI_ALLDONE as an error and returns a connection error. This causes valid DNS resolutions to fail in cases where the requests finish before the timeout elapses.

[yhirose]

@kgokalp thank you for the report! Could you please send the smallest possible code (main.cc) to reproduce this problem? Thanks!

[kgokalp]

I couldn’t reproduce the problem in a single main.cc with a simple example, it looks like it depends on timing and environment. However, in getaddrinfo_with_timeout, when I change the line
if (wait_result == 0)
to
if (wait_result == 0 || wait_result == EAI_ALLDONE)
everything works fine. This matches the glibc docs: EAI_ALLDONE just means all requests are already complete, so it shouldn’t be treated as an error.

[kgokalp]

This looks closely related to the other reported issue #2211

[yhirose]

@kgokalp great. Could you please send your patch as a pull request. You don't have to provide a unit test. Thanks!

[yhirose]

@kgokalp I merged the pull request. Could you verify it with the latest httplib.h on the master branch? Thanks!

[kgokalp]

I tested with the latest httplib.h from master and confirmed that the fix works as expected in my project. Thanks for the quick review and merge.

[yhirose]

Thanks for your fine contribution!