Zig

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 Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // 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
    // --------------------------------------------------------------------------------

    const http = try chilkat.Http.init();
    defer http.deinit();

    // 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:
    const cert = try chilkat.Cert.init();
    defer cert.deinit();
    cert.loadPfxFile("/myDir/API Project-1c43a291e2a1-notasecret.p12", "notasecret") catch {
        std.debug.print("{s}\n", .{try cert.getLastErrorText(alloc)});
        return;
    };

    // 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).

    const claim_params = try chilkat.Hashtable.init();
    defer claim_params.deinit();

    // The required claim parameters that must be provided by the application are
    // the "iss" and "scope" params:
    try claim_params.addStr("iss", "761326798069-r5mljlln1rd4lrbhg75efgigp36m78j5@developer.gserviceaccount.com");
    try claim_params.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.
    try claim_params.addStr("sub", "user@your-domain.com");

    // The "aud" parameter is optional.  If not set, it defaults to the value shown here:
    try claim_params.addStr("aud", "https://accounts.google.com/o/oauth2/token");

    const num_sec = 3600;

    const access_token = http.gSvcOauthAccessToken2(alloc, claim_params, num_sec, cert) catch "";
    if (!http.getLastMethodSuccess()) {
        std.debug.print("{s}\n", .{try http.getLastErrorText(alloc)});
    } else {
        std.debug.print("access token: {s}\n", .{access_token});
    }
}