Get the Contact Information of a Domain

$endpoint = "https://www.whogohost.com/host/modules/addons/DomainsReseller/api/index.php";
$action = "/domains/example.com/contact";
$params = [
    "domain" => "example.com",
];
$headers = [
    "username: email@example.com",
    "token: " . base64_encode(hash_hmac("sha256", "1234567890QWERTYUIOPASDFGHJKLZXCVBNM", "email@example.com:" . gmdate("y-m-d H")))
];
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, "{$endpoint}{$action}");
curl_setopt($curl, CURLOPT_POST, true);
curl_setopt($curl, CURLOPT_POSTFIELDS, http_build_query($params));
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, true);
curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
$response = curl_exec($curl);
curl_close($curl);