Connecting to OpenID using PHP cURL Showing Error - php

Question

I am using the following code to request a token from a IdentityServer, which uses OpenID protocol:
$curl = curl_init( 'https://remoteserver.com/connect/token' );
curl_setopt( $curl, CURLOPT_POST, true );
curl_setopt( $curl, CURLOPT_RETURNTRANSFER, 1);
$code = $_GET['code']; // The code from the previous request
$redirect_uri = 'http://mycalldomain.com/test.php';
curl_setopt( $curl, CURLOPT_POSTFIELDS, array(
'redirect_uri' => $redirect_uri,
'grant_type' => 'authorization_code'
) );
curl_setopt( $curl, CURLOPT_USERPWD,
"MYCLIENTID" . ":" .
"MYCLIENTSECRET");
$auth = curl_exec( $curl );
print '$auth = ';print_r($auth); // to see the error
$secret = json_decode($auth);
$access_key = $secret->access_token;
Is outputing the following error:
$auth = {"ErrorMessage":"Unsupported Mediatype"}
Can someone guide on this please?

Answer 1

You should provide a Content-Type HTTP header that the resource you're POSTing things accepts, by adding something like this:
curl_setopt($curl, CURLOPT_HTTPHEADER, array("Content-Type: application/json"));
That will make it JSON (as an example!), and your output data (CURLOPT_POSTFIELDS) must correspond to the Content-Type you choose.
Currently, the Content-Type is "multipart/form-data", as per the PHP documentation:
If value is an array, the Content-Type header will be set to multipart/form-data.
If you want to use the Content-Type "application/x-www-form-urlencoded", then in addition to setting that as the Content-Type, you have to give CURLOPT_POSTFIELDS in that format too. Being a web development language, PHP has a built-in function http_build_query for encoding arrays in that format:
curl_setopt($curl, CURLOPT_POSTFIELDS, http_build_query(array(
'redirect_uri' => $redirect_uri,
'grant_type' => 'authorization_code'
)));