Google Admin SDK: You are not authorized to access this API

Question

Since the Google Login Auth is disabled since last week I'm trying to get oAuth 2.0 working with a service account. We want to give users on our internal web application the oppurtunity to set there Out of Office.

I downloaded the lastest Google APIs Client Library for PHP. In the Google Developer Console, I have created a new project for my application and created a Service account credentials. I have also enabled the API service: Admin SDK in the Developer Console.

I have granted the account user ID access to the correct scopes (I think):

When I use the service-account.php example and change the details, I recieve an JSON with an access token, but when I do an CURL request (same as before) to get the e-mail settings from a user, the error "You are not authorized to access this API." occur.

My code:

<?php

include_once "templates/base.php";
require_once realpath(dirname(__FILE__) . '/../src/Google/autoload.php');
$client_id = '124331845-DELETEDPART-hbh89pbgl20citf6ko.apps.googleusercontent.com'; //Client ID
$service_account_name = '124331845-DELETEDPART-89pbgl20citf6ko@developer.gserviceaccount.com'; //Email Address
$key_file_location = 'globaltext-4ce09b20cb73.p12'; //key.p12

$client = new Google_Client();
if (isset($_SESSION['service_token'])) {
  $client->setAccessToken($_SESSION['service_token']);
}
$key = file_get_contents($key_file_location);
$cred = new Google_Auth_AssertionCredentials(
    $service_account_name,
    array('https://apps-apis.google.com/a/feeds/emailsettings/2.0/'),
    $key
);
$client->setAssertionCredentials($cred);
if ($client->getAuth()->isAccessTokenExpired()) {
  $client->getAuth()->refreshTokenWithAssertion($cred);
}

$aOutput = json_decode($client->getAccessToken());

$strEmailAdresSplit = explode('@', "[email protected]");
$strDomein = $strEmailAdresSplit[1];
$strAlias = $strEmailAdresSplit[0];

$resConnectionJobs = curl_init();
$aHeader = array();
$aHeader[] = 'Authorization: Bearer '.$aOutput->access_token; 
$aHeader[] = 'Content-Type: application/atom+xml'; 

curl_setopt($resConnectionJobs, CURLOPT_URL, "https://apps-apis.google.com/a/feeds/emailsettings/2.0/DOMAIN.EXTENSION/FIRSTNAME.LASTNAME/vacation"); 
curl_setopt($resConnectionJobs, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt($resConnectionJobs, CURLOPT_HTTPHEADER, $aHeader);
curl_setopt($resConnectionJobs, CURLOPT_RETURNTRANSFER, true);
curl_setopt($resConnectionJobs, CURLOPT_HEADER, false);

$oCurlData = curl_exec($resConnectionJobs);

curl_close($resConnectionJobs);
echo $oCurlData;

?>

Answer 1

Are you certain your credentials are OK?

Please try the following procedure to make sure you have the right credentials.

Creating your API keys

Go to the developer's console and follow these steps:

• Select your project
• Choose menu item "APIs & auth"
• Choose menu item "Registered app"
• Register an app of type "web application"
• Choose one of the following options, depending on what kind of app you're creating. Server side languages should use this option :
  • Key for server apps (with IP locking)

---

Getting access token & refresh token

Create a file that contains the following code :

<?php

if (isset($_GET['code'])) {
    // try to get an access token
    $code = $_GET['code'];
    $url = 'https://accounts.google.com/o/oauth2/token';
    $params = array(
        "code" => $code,
        "client_id" => YOUR_CLIENT_ID,
        "client_secret" => YOUR_CLIENT_SECRET,
        "redirect_uri" => 'http://' . $_SERVER["HTTP_HOST"] . $_SERVER["PHP_SELF"],
        "grant_type" => "authorization_code"
    );

    $ch = curl_init();
    curl_setopt($ch, constant("CURLOPT_" . 'URL'), $url);
    curl_setopt($ch, constant("CURLOPT_" . 'POST'), true);
    curl_setopt($ch, constant("CURLOPT_" . 'POSTFIELDS'), $params);
    $output = curl_exec($ch);
    $info = curl_getinfo($ch);
    curl_close($ch);
    if ($info['http_code'] === 200) {
        header('Content-Type: ' . $info['content_type']);
        return $output;
    } else {
        return 'An error happened';
    }
} else {

    $url = "https://accounts.google.com/o/oauth2/auth";

    $params = array(
        "response_type" => "code",
        "client_id" => YOUR_CLIENT_ID,
        "redirect_uri" => 'http://' . $_SERVER["HTTP_HOST"] . $_SERVER["PHP_SELF"],
        "scope" => "https://www.googleapis.com/auth/plus.me"
    );

    $request_to = $url . '?' . http_build_query($params);

    header("Location: " . $request_to);
}

Now, replace YOUR_CLIENT_ID and YOUR_CLIENT_SECRET with your client ID and client secret.

Make sure your scope is correct. For example, it should be https://www.googleapis.com/auth/analytics if you want to get access to Analytics.

If you run the file, you should get an OAuth2 approval screen.

If you now press Accept, you should get a result that looks like this:

{
  "access_token" : YOUR_ACCESS_TOKEN,
  "token_type" : "Bearer",
  "expires_in" : 3600,
  "refresh_token" : YOUR_REFRESH_TOKEN
}

The result may contain additional fields, depending on which scope you're applying for.

---

Connecting with Google's systems in background

Once you get the above to work, your application needs to implement the following workflow:

1) Check if your input contains a GET parameter named "code". If "code" is present, get a new access token and repeat this step (refresh your page) If "code" is not present, go to step 2.

2) Check if you have credentials stored for your service. If credentials are present, check if your access token has expired or will expire soon. Then go to step 3. If credentials are not present, go to the auth path of your service to get the auth code and go back to step 1 (make sure Google redirects to your current URL).

3) If refresh is needed, refresh your page and go back to step 1. If refresh is not needed, you're ready to actually do what you wanted to do in the first place.

---

Google's PHP library takes care if the oAuth2 flow for you, however. If you're using their library, each of the steps in the 3-step process are taken care of by the library and you should just be able to do whatever you want to do with Google's services straight away. I use this strategy myself in my Google Adwords dashboard.

You can, however, just write your custom library and connect with the service directly. Herebelow is some dev code from a project I wrote a few months ago. While it doesn't work out of the box (since it's a controller that's part of a larger application), it should help you understand the flow that Google's library takes care of under the hood.

namespace Application;

class Controller_API_Google_Youtube extends Controller_API {
    public function read() {
        $scope = "https://www.googleapis.com/auth/youtube";
        $this->doOauth($scope);
    }

    function doOauth($scope) {

        $oauth2Credentials = JSON_File::load(__DIR__ . DIRECTORY_SEPARATOR . 'Config.json');

        $paths = array(
            'token' => 'https://accounts.google.com/o/oauth2/token',
            'auth' => "https://accounts.google.com/o/oauth2/auth"
        );

       $refreshtime = 300;

        if (isset($_GET['code'])) {
            // Get access code
            $query = $_GET;
            unset($query['code']);
            if (count($query) > 0) {
                $query = '?' . http_build_query($query);
            } else {
                $query = '';
            }

            $client = \PowerTools\HTTP_Client::factory(
                        array(
                            'maps' => array(
                                'url' => $paths['token'],
                                'returntransfer' => 1,
                                'post' => true,
                                'postfields' => array(
                                    'code' => $_GET['code'],
                                    "client_id" => $oauth2Credentials['client_id'],
                                    "client_secret" => $oauth2Credentials['client_secret'],
                                    "redirect_uri" => HTTP_PROTOCOL . URL_PATH . $query,
                                    "grant_type" => "authorization_code"
                                )
                            )
                        )
            )->execute();
            $responses = $client->getResponses();
            $response = array_pop($responses);
            $info = $response['maps']->getInfo();
            $content = $response['maps']->getContent();
            if ($info['http_code'] === 200) {
                $output = JSON::decode($content);
                $oauth2Credentials[$scope] = array();
                $oauth2Credentials[$scope]['expires'] = time() + $output['expires_in'];
                $oauth2Credentials[$scope]['access_token'] = $output['access_token'];
                $oauth2Credentials[$scope]['refresh_token'] = $output['refresh_token'];
                file_put_contents(__DIR__ . DIRECTORY_SEPARATOR . 'Config.json', JSON::encode($oauth2Credentials));
                header("Location: " . HTTP_PROTOCOL . URL_PATH . $query);
            } else {
                echo "Something went wrong";
            }
        } elseif (!isset($oauth2Credentials[$scope])) {
            // Get auth code

            header("Location: " . $paths['auth'] . '?' . http_build_query(
                        array(
                            "response_type" => "code",
                            "client_id" => $oauth2Credentials['client_id'],
                            "redirect_uri" => HTTP_PROTOCOL . DOMAIN_PATH,
                            "scope" => $scope
                        )
            ));
        } elseif ($oauth2Credentials[$scope]['expires'] - $refreshtime < time()) {
            // Refresh access code

            $client = \PowerTools\HTTP_Client::factory(
                        array(
                            'maps' => array(
                                'url' => $paths['token'],
                                'returntransfer' => 1,
                                'post' => true,
                                'postfields' => array(
                                    "client_id" => $oauth2Credentials['client_id'],
                                    "client_secret" => $oauth2Credentials['client_secret'],
                                    "refresh_token" => $oauth2Credentials[$scope]['refresh_token'],
                                    "grant_type" => "refresh_token"
                                )
                            )
                        )
            )->execute();
            $responses = $client->getResponses();
            $response = array_pop($responses);
            $info = $response['maps']->getInfo();
            $content = $response['maps']->getContent();
            if ($info['http_code'] === 200) {
                $output = JSON::decode($response['maps']->getContent());
                $oauth2Credentials[$scope]['expires'] = time() + $output['expires_in'];
                $oauth2Credentials[$scope]['access_token'] = $output['access_token'];
                file_put_contents(__DIR__ . DIRECTORY_SEPARATOR . 'Config.json', JSON::encode($oauth2Credentials));
                $this->read();
            } else {
                $this->output = array("error" => "Something went wrong");
            }
        } else {
            $this->doSomethinguseful($oauth2Credentials, $scope);
        }
        return $this;
    }


    function doSomethinguseful($oauth2Credentials, $scope) {
        // https://developers.google.com/youtube/v3/sample_requests?hl=nl
        $client = \PowerTools\HTTP_Client::factory(
                    array(
                        'maps' => array(
                            'useragent' => 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.13) Gecko/20080311 Firefox/2.0.0.13',
                            'url' => 'https://www.googleapis.com/youtube/v3/channels?part=contentDetails&mine=true',
                            'returntransfer' => true,
                            'httpheader' => array(
                                'Authorization: Bearer ' . $oauth2Credentials[$scope]['access_token'],
                                'Accept-Encoding: gzip, deflate'
                            )
                        )
                    )
        )->execute();
        $responses = $client->getResponses();
        $response = array_pop($responses);
        $content = $response['maps']->getContent();
        $this->output = JSON::decode(gzdecode($content));
    }
}