(PHP Extension) Refresh Access Token on 401 Unauthorized and Retry

Demonstrates how to handle an expired access token error, refresh the token, and retry the request. (In this case, the request is to download an object from Google Cloud Storage.)

Chilkat PHP Downloads PHP Extension for Windows, Linux, MAC OS X, Alpine Linux, Solaris, OpenBSD, FreeBSD, and Linux armhf/aarch64

<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// This example uses a previously obtained access token having permission for the 
// scope "https://www.googleapis.com/auth/cloud-platform"

// In this example, Get Google Cloud Storage OAuth2 Access Token, 
// the service account access token was saved to a text file.  This example fetches the access token from the file..
$sbToken = new CkStringBuilder();
$success = $sbToken->LoadFile('qa_data/tokens/googleCloudStorageAccessToken.txt','utf-8');
if ($success == false) {
    print 'Failed to load access token.' . "\n";
    exit;
}

$http = new CkHttp();

$http->put_AuthToken($sbToken->getAsString());

// Construct a URL to download an object named "starfish.jpg" from the "chilkat-ocean" bucket.
$http->SetUrlVar('bucket_name','chilkat-ocean');
$http->SetUrlVar('object_name','starfish.jpg');
$url = 'https://www.googleapis.com/storage/v1/b/{$bucket_name}/o/{$object_name}?alt=media';

// If there is an error response, then we didn't actually download the file data,
// but instead we downloaded an error response..
$fileData = new CkBinData();
$success = $http->DownloadBd($url,$fileData);
$responseCode = $http->get_LastStatus();
if (($success == false) and ($responseCode != 401)) {
    print $http->lastErrorText() . "\n";
    exit;
}

if ($responseCode == 401) {
    print 'Received 401 Unauthorized response. Attempting to refresh the access token...' . "\n";

    // May be that the access token expired.
    // Load our JSON key and request a new access token, then retry the original request.
    $fac = new CkFileAccess();
    $jsonKey = $fac->readEntireTextFile('qa_data/googleApi/ChilkatCloud-13a07a2e8b3f.json','utf-8');
    if ($fac->get_LastMethodSuccess() != true) {
        print $fac->lastErrorText() . "\n";
        exit;
    }

    $gAuth = new CkAuthGoogle();
    $gAuth->put_JsonKey($jsonKey);
    $gAuth->put_Scope('https://www.googleapis.com/auth/cloud-platform');
    $gAuth->put_ExpireNumSeconds(3600);
    $gAuth->put_SubEmailAddress('');

    $tlsSock = new CkSocket();
    $success = $tlsSock->Connect('www.googleapis.com',443,true,5000);
    if ($success != true) {
        print $tlsSock->lastErrorText() . "\n";
        exit;
    }

    $success = $gAuth->ObtainAccessToken($tlsSock);
    if ($success != true) {
        print $gAuth->lastErrorText() . "\n";
        exit;
    }

    $fac->WriteEntireTextFile('qa_data/tokens/googleCloudStorageAccessToken.txt',$gAuth->accessToken(),'utf-8',false);

    // Retry the original request.
    $http->put_AuthToken($gAuth->accessToken());
    $success = $http->DownloadBd($url,$fileData);
    if ($success == false) {
        print $http->lastErrorText() . "\n";
        exit;
    }

}

if ($responseCode != 200) {
    // Get the error response
    $sbErrorResponse = new CkStringBuilder();
    $sbErrorResponse->AppendBd($fileData,'utf-8',0,0);
    print 'Error response code = ' . $responseCode . "\n";
    print 'Error:' . "\n";
    print $sbErrorResponse->getAsString() . "\n";
    exit;
}

print 'Success.' . "\n";

// Save the downloaded data to a file.
$success = $fileData->WriteFile('qa_output/starfish.jpg');

?>