Zig

Refresh Access Token on 401 Unauthorized and Retry (Service Account)

See more Google Cloud Storage Examples

Demonstrates how to handle an expired access token error, refresh the token, and retry the request. (In this case, the request is to download an object from Google Cloud Storage.) Zig

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

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

    var success: bool = false;

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

    // This example uses a previously obtained access token having permission for the
    // scope "https://www.googleapis.com/auth/cloud-platform"

    // In this example, Get Google Cloud Storage OAuth2 Access Token,
    // the service account access token was saved to a text file.  This example fetches the access token from the file..
    const sb_token = try chilkat.StringBuilder.init();
    defer sb_token.deinit();
    success = if (sb_token.loadFile("qa_data/tokens/googleCloudStorageAccessToken.txt", "utf-8")) true else |_| false;
    if (!success) {
        std.debug.print("Failed to load access token.\n", .{});
        return;
    }

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

    http.setAuthToken(try sb_token.getAsString(alloc));

    // Construct a URL to download an object named "starfish.jpg" from the "chilkat-ocean" bucket.
    http.setUrlVar("bucket_name", "chilkat-ocean") catch {};
    http.setUrlVar("object_name", "starfish.jpg") catch {};
    const url = "https://www.googleapis.com/storage/v1/b/{$bucket_name}/o/{$object_name}?alt=media";

    // If there is an error response, then we didn't actually download the file data,
    // but instead we downloaded an error response..
    const file_data = try chilkat.BinData.init();
    defer file_data.deinit();
    success = if (http.downloadBd(url, file_data)) true else |_| false;
    const response_code = http.getLastStatus();
    if ((!success) and (response_code != 401)) {
        std.debug.print("{s}\n", .{try http.getLastErrorText(alloc)});
        return;
    }

    if (response_code == 401) {
        std.debug.print("Received 401 Unauthorized response. Attempting to refresh the access token...\n", .{});

        // May be that the access token expired.
        // Load our JSON key and request a new access token, then retry the original request.
        const fac = try chilkat.FileAccess.init();
        defer fac.deinit();
        const json_key = fac.readEntireTextFile(alloc, "qa_data/googleApi/ChilkatCloud-13a07a2e8b3f.json", "utf-8") catch {
            std.debug.print("{s}\n", .{try fac.getLastErrorText(alloc)});
            return;
        };

        const g_auth = try chilkat.AuthGoogle.init();
        defer g_auth.deinit();
        g_auth.setJsonKey(json_key);
        g_auth.setScope("https://www.googleapis.com/auth/cloud-platform");
        g_auth.setExpireNumSeconds(3600);
        g_auth.setSubEmailAddress("");

        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;
        };

        g_auth.obtainAccessToken(tls_sock) catch {
            std.debug.print("{s}\n", .{try g_auth.getLastErrorText(alloc)});
            return;
        };

        fac.writeEntireTextFile("qa_data/tokens/googleCloudStorageAccessToken.txt", try g_auth.getAccessToken(alloc), "utf-8", false) catch {};

        // Retry the original request.
        http.setAuthToken(try g_auth.getAccessToken(alloc));
        http.downloadBd(url, file_data) catch {
            std.debug.print("{s}\n", .{try http.getLastErrorText(alloc)});
            return;
        };
    }

    if (response_code != 200) {
        // Get the error response
        const sb_error_response = try chilkat.StringBuilder.init();
        defer sb_error_response.deinit();
        sb_error_response.appendBd(file_data, "utf-8", 0, 0) catch {};
        std.debug.print("Error response code = {d}\n", .{response_code});
        std.debug.print("Error:\n", .{});
        std.debug.print("{s}\n", .{try sb_error_response.getAsString(alloc)});
        return;
    }

    std.debug.print("Success.\n", .{});

    // Save the downloaded data to a file.
    success = if (file_data.writeFile("qa_output/starfish.jpg")) true else |_| false;
}