Zig

Get Google API Access Token using JSON Private Key using NIST Time Server Date/Time

Demonstrates how to get a Google API access token using a JSON service account private key, using the NIST time server date/time rather than the local system date/time. Zig

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

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

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

    // First, let's get the current date/time from time-c.nist.gov
    const socket = try chilkat.Socket.init();
    defer socket.deinit();

    // Connect to an NIST time server and read the current date/time
    var max_wait_ms: i32 = 8000;
    const use_tls = false;
    socket.connect("time-c.nist.gov", 37, use_tls, max_wait_ms) catch {
        std.debug.print("{s}\n", .{try socket.getLastErrorText(alloc)});
        return;
    };

    // The time server will send a big-endian 32-bit integer representing
    // the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
    // The ReceiveInt32 method will receive a 4-byte integer, but returns
    // true or false to indicate success.  If successful, the integer
    // is obtained via the ReceivedInt property.
    const big_endian = true;
    socket.receiveInt32(big_endian) catch {
        std.debug.print("{s}\n", .{try socket.getLastErrorText(alloc)});
        return;
    };

    const dt = try chilkat.DateTime.init();
    defer dt.deinit();
    dt.setFromNtpTime(socket.getReceivedInt()) catch {};

    // Show the current local date/time
    const b_local_time = true;
    std.debug.print("Current local date/time: {s}\n", .{try dt.getAsRfc822(alloc, b_local_time)});

    max_wait_ms = 10;
    socket.close(max_wait_ms) catch {};

    // ------------------------------------------------------------------------
    // OK, we have the current date/time.  We'll use it to set the IAT property
    // in the code below.

    // First load the JSON key into a string.
    const fac = try chilkat.FileAccess.init();
    defer fac.deinit();
    const json_key = fac.readEntireTextFile(alloc, "qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json", "utf-8") catch {
        std.debug.print("{s}\n", .{try fac.getLastErrorText(alloc)});
        return;
    };

    // A JSON private key should look like this:

    //     {
    //       "type": "service_account",
    //       "project_id": "chilkattest-1350",
    //       "private_key_id": "fa2e36ee26986eab628b59868af8bec1d1c64c38",
    //       "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIjFa...28N64N2n1E4FYzBZjSdy\n-----END PRIVATE KEY-----\n",
    //       "client_email": "598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a@developer.gserviceaccount.com",
    //       "client_id": "598922945226-00rb0ppfg0snd9jo7bhvd4v17jtj2d3a.apps.googleusercontent.com",
    //       "auth_uri": "https://accounts.google.com/o/oauth2/auth",
    //       "token_uri": "https://accounts.google.com/o/oauth2/token",
    //       "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
    //       "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a%40developer.gserviceaccount.com"
    //     }

    const g_auth = try chilkat.AuthGoogle.init();
    defer g_auth.deinit();
    g_auth.setJsonKey(json_key);

    // Choose a scope.
    g_auth.setScope("https://www.googleapis.com/auth/cloud-platform");

    // Request an access token that is valid for this many seconds.
    g_auth.setExpireNumSeconds(3600);

    // If the application is requesting delegated access:
    // The email address of the user for which the application is requesting delegated access,
    // then set the email address here. (Otherwise leave it empty.)
    g_auth.setSubEmailAddress("");

    // ------------------------------------------------------------------------
    // Set the IAT using the date/time from the NIST time server.
    const unix_time = @as(i32, @intCast(dt.getAsUnixTime(false)));
    std.debug.print("unixTime = {d}\n", .{unix_time});
    g_auth.setIat(unix_time);

    // Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
    // The Chilkat socket object is used so that the connection can be established
    // through proxies or an SSH tunnel if desired.
    const tls_sock = try chilkat.Socket.init();
    defer tls_sock.deinit();
    tls_sock.connect("www.googleapis.com", 443, true, 5000) catch {
        std.debug.print("{s}\n", .{try tls_sock.getLastErrorText(alloc)});
        return;
    };

    // Send the request to obtain the access token.
    g_auth.obtainAccessToken(tls_sock) catch {
        std.debug.print("{s}\n", .{try g_auth.getLastErrorText(alloc)});
        return;
    };

    // Examine the access token:
    std.debug.print("Access Token: {s}\n", .{try g_auth.getAccessToken(alloc)});
}