Thirdparty API call is failing within payment gateway callback file

[kobopulse]

I had successfully set up and integrated a third party payment integration system for a client on WHMCS. Inorder to Validate callback authenticity, the gateway provides a method of verifying that a callback

originated from them as shown in code below:

 

$mertid ='secretmerchantID';
$amt = '10000';
$tranxid = 'gtPay130958397220820';
$hashkey ='secretclientkey';

$hash =  hash('sha512', $mertid . $tranxid . $hashkey);

$url = 'https://ibank.gtbank.com/GTPayService/gettransactionstatus.xml?mertid='.$mertid.'&amount='.$amt.'&tranxid='.$tranxid.'&hash='.$hash;


$xmlString = file_get_contents($url);
if($xmlString === false)
{
echo "Response Description: GTPAY Verification service failed to open. 
       Please wait as the page reloads  in 5 seconds";
}
else
{
$xml = simplexml_load_string($xmlString );

var_dump($xml);
}

 

 

I am using the file_get_contents function to read the API response into a string, then simplexml_load_string function to Interprets the string of XML into an object with properties containing the data held within the xml string. On each successful transaction run $xml=simplexml_load_string($jString), returns FALSE.

 

However when I call this code in a file directly in a browser using the same transaction values, then $xml=simplexml_load_string($jString), returns the string of XML into an object as expected.

 

Strangely, when I place this code in a file within WHMCS root folder and I attempt to call directly in a browser using the same successful transaction values, then $xml=simplexml_load_string($jString), returns FALSE again.

 

What may be restricting this call to Third party API call within the WHMCS install?

 

Thanks