[php] CURL and HTTPS, "Cannot resolve host"

I'm trying to fetch the contents of a page using CURL. The page that is doing the fetching is https and the page it is trying to fetch is also https. I'm getting an error "Couldn't resolve host" with all of the settings I try.

$c=curl_init();
curl_setopt($c, CURLOPT_URL,$url);
//curl_setopt($c, CURLOPT_USERAGENT, "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:x.x.x) Gecko/20041107 Firefox/x.x");
curl_setopt ($c, CURLOPT_RETURNTRANSFER, TRUE);
//curl_setopt($c, CURLOPT_SSL_VERIFYPEER, TRUE);
//curl_setopt($c, CURLOPT_SSL_VERIFYHOST, TRUE);
curl_setopt($c, CURLOPT_HEADER, FALSE);

$html=curl_exec($c);

if($html === false) {
    echo curl_error($c);
}
else {
    echo 'Operation completed without any errors';
}   


curl_close($c);

Any ideas?

Just a note which may be helpful- I was having this trouble with Apache on my laptop (which connects by wifi AFTER startup), and restarting the server (after connect) fixed the issue. I guess in my case this may be to do with apache starting offline and perhaps there noting that DNS lookups fail?

Your getting the error because you're probably doing it on your Local server environment. You need to skip the certificates check when the cURL call is made. For that just add the following options

curl_setopt($c, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($c, CURLOPT_SSL_VERIFYHOST,  0);

We need to add host security certificate to php.ini file. For local developement enviroment we can add cacert.pem in your local php.ini.

do phpinfo(); and file your php.ini path open and add uncomment ;curl.capath

curl.capath=path_of_your_cacert.pem

I found that CURL can decide to use IPv6, in which case it tries to resolve but doesn't get an IPv6 answer (or something to that effect) and times out.

You can try the command line switch -4 to test this out.

In PHP, you can configure this line by setting this:

curl_setopt($_h, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4 );

There is a current bug in glibc on Ubuntu which can have this effect: https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1674733

To resolve it, update libc and all related (Packages that will be upgraded: libc-bin libc-dev-bin libc6 libc6-dev libfreetype6 libfreetype6-dev locales multiarch-support) and restart the server.

If you do it on Windows XAMPP/WAMP it probaly won't work as in my case.

I solved the problem setting up Laravel's Homestead/Vagrant solution to create my (Ubuntu) development environment - it has built-in: Nginx, PHP 5.6, PHP 7.3, PHP 7.2, PHP 7.1, MySQL, PostgreSQL, Redis, Memcached, Node... to name just a few.

See here for info how to set up the environment - it's really worth the effort!

Laravel Homestead is an official, pre-packaged Vagrant box that provides you a wonderful development environment without requiring you to install PHP, a web server, and any other server software on your local machine. No more worrying about messing up your operating system! Vagrant boxes are completely disposable. If something goes wrong, you can destroy and re-create the box in minutes!

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After tried all above, still can't resolved my issue yet. But got new solution for my problem.

At server where you are going to make a request, there should be a entry of your virtual host.

sudo vim /etc/hosts

and insert

192.xxx.x.xx www.domain.com

The reason if you are making request from server to itself then, to resolve your virtual host or to identify it, server would need above stuff, otherwise server won't understand your requesting(origin) host.

You may have to enable the HTTPS part:

curl_setopt($c, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt($c, CURLOPT_SSL_VERIFYHOST,  2);

And if you need to verify (authenticate yourself) you may need this too:

curl_setopt($c, CURLOPT_USERPWD, 'username:password');

add yourlocalhost
ex. 127.0.0.1 cards.localhost in the /etc/hosts directory. Now restart apache server

I had the same problem. Coudn't resolve google.com. There was a bug somewhere in php fpm, which i am using. Restarting php-fpm solved it for me.