How can I verify a Google authentication API access token?

Question

How can I verify a Google authentication access token?

I need to somehow query Google and ask: Is [given access token] valid for the [exampl

Answer 1

function authenticate_google_OAuthtoken($user_id)
{
    $access_token   = google_get_user_token($user_id); // get existing token from DB
    $redirecturl    = $Google_Permissions->redirecturl;
    $client_id      = $Google_Permissions->client_id;
    $client_secret  = $Google_Permissions->client_secret;
    $redirect_uri   = $Google_Permissions->redirect_uri;
    $max_results    = $Google_Permissions->max_results;

    $url = 'https://www.googleapis.com/oauth2/v1/tokeninfo?access_token='.$access_token;
    $response_contacts  =  curl_get_responce_contents($url);
    $response   =   (json_decode($response_contacts));

    if(isset($response->issued_to))
    {
        return true;
    }
    else if(isset($response->error))
    {
        return false;
    }
}