Google Recaptcha check timeout due to IPv6 issue - php on IIS

Question

I'm using google recaptcha v2 on my websites (html / php).

On the server side I am trying to contact google recaptcha to check the user's input:

$response = file_get_contents("https://www.google.com/recaptcha/api/siteverify?secret=".$privatekey."&response=".$_POST['g-recaptcha-response']);

The line above is not working. It normally just times out. Occasionally it will work though.

IPv6 is the Issue

It appears to be an issue with the call to google resolving to IPv6 (from https://github.com/google/recaptcha/issues/193)

I have tried turning off IPv6 on my internet connection and that makes it work.

How do I fix this issue properly? I don't think I could turn off IPv6 on the servers (we use some shared hosting as well as a VPS). Is there a way to force it to resolve to IPv4?

Thanks!

Answer 1

Issue was that php could not verify the SSL certificate. The IPv4 / IPv6 was a bit of a red herring I think.

Great post here on that: file_get_contents(): SSL operation failed with code 1. And more