What version of PHP is the server running?
What version of cURL is being used?

Found some time to take a little deeper look at this thread and the differences between the "lphp.php" and "class.linkpoint_api.php"... Can you try the following changes in "/includes/modules/payment/linkpoint_api/class.linkpoint_api.php" (changes in red):
Code:
$ch = curl_init ();
curl_setopt ($ch, CURLOPT_URL,$host);
curl_setopt ($ch, CURLOPT_POST, 1);
curl_setopt ($ch, CURLOPT_POSTFIELDS, $xml);
curl_setopt ($ch, CURLOPT_SSLCERT, $key);
// curl_setopt ($ch, CURLOPT_CAINFO, $key);
// curl_setopt ($ch, CURLOPT_SSL_VERIFYHOST, 2); // NOTE: Leave commented-out (removed in cURL 7.28.1)! This should NEVER be set to 0 in production!!!! (0 disables remote certificate "Common Name (CN)" verification against the remote server)
// curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, true); // NOTE: Leave commented-out! or set to TRUE! This should NEVER be set to FALSE in production!!!! (FALSE disables all remote certificate verifications)
curl_setopt ($ch, CURLOPT_SSLVERSION, 3);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, true);
This should allow cURL to use the CA Bundle configured on the server (instead of trying to validate the remote linkpoint server certificate against the local linkpoint client certificate). For some reason I missed CURLOPT_CAINFO being set in the previous post.


Quote Originally Posted by mprough View Post
... So if the communication is failed, then why would the log also trigger approved? ...
Good question... When the transaction has been declined, the block starting at line 560 of "linkpoint_api.php" should trigger a redirect to the checkout payment page w/ an appropriate message to the customer... I did notice both versions of the Linkpoint API do not ensure r_approved will be returned after the initial processing of data via cURL...

The following changes should help ensure r_approved is set to a failure when not present. This should hopfully take care of the "Illegal string offset" error as well. Starting around line 811 in "/includes/modules/payment/linkpoint_api.php" (changes in red):
Code:
    include(DIR_FS_CATALOG . DIR_WS_MODULES . 'payment/linkpoint_api/class.linkpoint_api.php');
    $mylphp = new lphp;

    // Send transaction, using cURL
    $result = $mylphp->curl_process($myorder);
    if(!is_array($result)) {
    	$result = array(
    	  'r_approved' => 'FAILURE',
    	  'r_error' => 'Communications Error'
    	);
    }
    else if(!array_key_exists('r_approved', $result)) {
      $result['r_approved'] = 'FAILURE';
      $result['r_error'] = 'Communications Error';
    }

    // do debug output
    $errorMessage = date('M-d-Y h:i:s') . "\n=================================\n\n" . ($mylphp->commError !='' ? $mylphp->commError . "\n\n" : '') . 'Response Code: ' . $result["r_approved"] . ' ' . $result["r_error"] . "\n\n=================================\n\n" . 'Sending to Gateway: ' . "\n" . $mylphp->sendData . "\n\n" . 'Result: ' . substr(print_r($result, true), 5) . "\n\n";
    if ($mylphp->commError != '') $errorMessage .= $mylphp->commError . "\n" . 'CURL info: ' . print_r($mylphp->commInfo, true) . "\n";
    if (CURL_PROXY_REQUIRED == 'True') $errorMessage .= 'Using CURL Proxy: [' . CURL_PROXY_SERVER_DETAILS . ']  with Proxy Tunnel: ' .($proxy_tunnel_flag ? 'On' : 'Off') . "\n";
    $failure = ($result["r_approved"] != "APPROVED" ? true : false);
Not sure this the the best possible solution, but am curious to see what effect (if any) the changes have upon the situation...


NOTE: The above changes are have not been fully tested (and may contain errors). They are merely suggestions. Please test thoroughly before applying to a production website.