Perl

Get OAuth 2.0 Access Token using G_SvcOauthAccessToken2

Obtains an OAUTH2 access token from the Google OAuth 2.0 Authorization Server using the G_SvcOauthAccessToken2 method. This is for Server to server applications using Google API's that need an access token. See https://developers.google.com/accounts/docs/OAuth2ServiceAccount Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

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

# --------------------------------------------------------------------------------
# For a step-by-step guide for setting up your Google Workspace service account,
# see Setup Google Workspace Account for Sending SMTP GMail from a Service Account
# --------------------------------------------------------------------------------

my $http = Chilkat2::Http->new;

# When a service account (Client ID) is created at https://code.google.com/apis/console/
# Google will generate a P12 key.  This is a PKCS12 (PFX) file that you will download
# and save.  The password to access the contents of this file is "notasecret".
# NOTE: The Chilkat Pfx API provides the ability to load a PFX/P12 and re-save
# with a different password.

# Begin by loading the downloaded .p12 into a Chilkat certificate object:
my $cert = Chilkat2::Cert->new;
my $success = $cert->LoadPfxFile('/myDir/API Project-1c43a291e2a1-notasecret.p12', 'notasecret');
if (!$success) {
    print $cert->LastErrorText, "\n";
    exit;
}

# The next (and final) step is to request the access token.  Chilkat internally
# does all the work of forming the JWT header and JWT claim set, encoding and
# signing the JWT, and sending the access token request.
# The application need only provide the inputs: The iss, scope(s), sub, and the
# desired duration with a max of 3600 seconds (1 hour).
#
# Each of these inputs is defined as follows
# (see https://developers.google.com/accounts/docs/OAuth2ServiceAccount
# iss: The email address of the service account.
# scope: A space-delimited list of the permissions that the application requests.
# sub: The email address of the user for which the application is requesting delegated access.
# numSec: The number of seconds for which the access token will be valid (max 3600).

my $claimParams = Chilkat2::Hashtable->new;

# The required claim parameters that must be provided by the application are
# the "iss" and "scope" params:
$success = $claimParams->AddStr('iss', '761326798069-r5mljlln1rd4lrbhg75efgigp36m78j5@developer.gserviceaccount.com');
$success = $claimParams->AddStr('scope', 'https://mail.google.com/');

# The "sub" param is required if there is an email address, such as for a
# Google Apps domain—if you use Google Apps for Work, where the administrator of the Google Apps domain
# can authorize an application to access user data on behalf of users in the Google Apps domain.
#
# Comment out this line if there is no such email address.
$success = $claimParams->AddStr('sub', 'user@your-domain.com');

# The "aud" parameter is optional.  If not set, it defaults to the value shown here:
$success = $claimParams->AddStr('aud', 'https://accounts.google.com/o/oauth2/token');

my $numSec = 3600;

my $accessToken = $http->G_SvcOauthAccessToken2($claimParams, $numSec, $cert);
if (!$http->LastMethodSuccess) {
    print $http->LastErrorText, "\n";
} else {
    print 'access token: ', $accessToken, "\n";
}