Zig

Refresh Expiring OAuth2 Access Token for Azure Registered App

See more OAuth2 Examples

Shows how to renew an Azure App's access token using the refresh token when it's near expiration. Zig

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

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

    // We previously obtained an access token and saved the JSON to a file using this example:
    // Get OAuth2 Access Token for Azure Registered App

    // This example will examine the JSON and expiration date, and if near expiration will
    // refresh the access token.

    const json = try chilkat.JsonObject.init();
    defer json.deinit();
    json.loadFile("qa_data/tokens/_myAzureApp.json") catch {
        std.debug.print("Failed to load the access token.\n", .{});
        return;
    };

    // The contents of the JSON look like this:
    // {
    //   "token_type": "Bearer",
    //   "scope": "User.Read Mail.ReadWrite Mail.Send",
    //   "expires_in": 3600,
    //   "ext_expires_in": 0,
    //   "access_token": "EwBAA8l6B...",
    //   "refresh_token": "MCRMdbe6Cd...",
    //   "id_token": "eyJ0eXAiOiJ...",
    //   "expires_on": "1494112119"
    // }

    // The "expires_on" value is a Unix time.
    const dt_expire = try chilkat.DateTime.init();
    defer dt_expire.deinit();
    dt_expire.setFromUnixTime(false, @as(u32, @intCast(json.intOf("expires_on")))) catch {};

    // If this date/time expires within 10 minutes of the current system time, refresh the token.
    if (!dt_expire.expiresWithin(10, "minutes")) {
        std.debug.print("No need to refresh, the access token won't expire within the next 10 minutes.\n", .{});
        return;
    }

    // OK, we need to refresh the access token..
    const oauth2 = try chilkat.OAuth2.init();
    defer oauth2.deinit();

    // Note: The endpoint depends on the Azure App Registration.
    // See How to Choose the Correct Endpoints for your Azure App Registration
    oauth2.setTokenEndpoint("https://login.microsoftonline.com/common/oauth2/v2.0/token");

    // Use your client ID.
    oauth2.setClientId("CLIENT_ID");

    // Get the existing refresh token.
    oauth2.setRefreshToken(try json.stringOf(alloc, "refresh_token"));

    // Send the HTTP POST to refresh the access token.
    oauth2.refreshAccessToken() catch {
        std.debug.print("{s}\n", .{try oauth2.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("OAuth2 authorization granted!\n", .{});
    std.debug.print("Access Token = {s}\n", .{try oauth2.getAccessToken(alloc)});

    // Get the full JSON response:
    json.load(try oauth2.getAccessTokenResponse(alloc)) catch {};
    json.setEmitCompact(false);

    // If an "expires_on" member does not exist, then add the JSON member by
    // getting the current system date/time and adding the "expires_in" seconds.
    // This way we'll know when the token expires.
    if (!json.hasMember("expires_on")) {
        dt_expire.setFromCurrentSystemTime() catch {};
        dt_expire.addSeconds(json.intOf("expires_in")) catch {};
        json.appendString("expires_on", try dt_expire.getAsUnixTimeStr(alloc, false)) catch {};
    }

    std.debug.print("{s}\n", .{try json.emit(alloc)});

    // Save the new access token JSON to a file for future requests.
    const fac = try chilkat.FileAccess.init();
    defer fac.deinit();
    fac.writeEntireTextFile("qa_data/tokens/_myAzureApp.json", try json.emit(alloc), "utf-8", false) catch {};
}