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CURL and HTTPS, “Cannot resolve host”

Posted by: admin November 29, 2017 Leave a comment

Questions:

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?

Answers:

Maybe a DNS issue?

Try your URL against this code:

$_h = curl_init();
curl_setopt($_h, CURLOPT_HEADER, 1);
curl_setopt($_h, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($_h, CURLOPT_HTTPGET, 1);
curl_setopt($_h, CURLOPT_URL, 'YOUR_URL' );
curl_setopt($_h, CURLOPT_DNS_USE_GLOBAL_CACHE, false );
curl_setopt($_h, CURLOPT_DNS_CACHE_TIMEOUT, 2 );

var_dump(curl_exec($_h));
var_dump(curl_getinfo($_h));
var_dump(curl_error($_h)); 

Questions:
Answers:

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 );

Questions:
Answers:

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.

Questions:
Answers:

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?

Questions:
Answers:

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.

Questions:
Answers:

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

Questions:
Answers:

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

Questions:
Answers:

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);

Questions:
Answers:

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');

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