import { env } from "cloudflare:workers";
import type { AuthRequest, OAuthHelpers } from "@cloudflare/workers-oauth-provider";
import { Hono } from "hono";
import { fetchUpstreamAuthToken, getUpstreamAuthorizeUrl, type Props } from "./utils";
import {
clientIdAlreadyApproved,
parseRedirectApproval,
renderApprovalDialog,
} from "./workers-oauth-utils";
const app = new Hono<{ Bindings: Env & { OAUTH_PROVIDER: OAuthHelpers } }>();
app.get("/authorize", async (c) => {
const oauthReqInfo = await c.env.OAUTH_PROVIDER.parseAuthRequest(c.req.raw);
const { clientId } = oauthReqInfo;
if (!clientId) {
return c.text("Invalid request", 400);
}
if (
await clientIdAlreadyApproved(c.req.raw, oauthReqInfo.clientId, env.COOKIE_ENCRYPTION_KEY)
) {
return redirectToGoogle(c.req.raw, oauthReqInfo);
}
return renderApprovalDialog(c.req.raw, {
client: await c.env.OAUTH_PROVIDER.lookupClient(clientId),
server: {
description: "This is a demo MCP Remote Server using Google for authentication.",
logo: "https://developers.google.com/identity/images/g-logo.png",
name: "Cloudflare Google MCP Server", // optional
},
state: { oauthReqInfo }, // arbitrary data that flows through the form submission below
});
});
app.post("/authorize", async (c) => {
// Validates form submission, extracts state, and generates Set-Cookie headers to skip approval dialog next time
const { state, headers } = await parseRedirectApproval(c.req.raw, env.COOKIE_ENCRYPTION_KEY);
if (!state.oauthReqInfo) {
return c.text("Invalid request", 400);
}
return redirectToGoogle(c.req.raw, state.oauthReqInfo, headers);
});
async function redirectToGoogle(
request: Request,
oauthReqInfo: AuthRequest,
headers: Record<string, string> = {},
) {
return new Response(null, {
headers: {
...headers,
location: getUpstreamAuthorizeUrl({
client_id: env.GOOGLE_CLIENT_ID,
redirect_uri: new URL("/callback", request.url).href,
scope: "openid email profile",
state: btoa(JSON.stringify(oauthReqInfo)),
upstream_url: "https://accounts.google.com/o/oauth2/v2/auth",
}),
},
status: 302,
});
}
/**
* OAuth Callback Endpoint
*
* This route handles the callback from Google after user authentication.
* It exchanges the temporary code for an access token, then stores some
* user metadata & the auth token as part of the 'props' on the token passed
* down to the client. It ends by redirecting the client back to _its_ callback URL
*/
app.get("/callback", async (c) => {
const oauthReqInfo = JSON.parse(atob(c.req.query("state") as string)) as AuthRequest;
if (!oauthReqInfo.clientId) {
return c.text("Invalid state", 400);
}
// Exchange the code for an access token
const [tokenResponse, errResponse] = await fetchUpstreamAuthToken({
client_id: c.env.GOOGLE_CLIENT_ID,
client_secret: c.env.GOOGLE_CLIENT_SECRET,
code: c.req.query("code"),
redirect_uri: new URL("/callback", c.req.url).href,
upstream_url: "https://oauth2.googleapis.com/token",
});
if (errResponse) return errResponse;
const { access_token, id_token } = tokenResponse as any;
// Fetch the user info from Google
let userInfo: any = {};
try {
const userInfoRes = await fetch("https://openidconnect.googleapis.com/v1/userinfo", {
headers: {
Authorization: `Bearer ${access_token}`,
},
});
if (!userInfoRes.ok) {
return c.text("Failed to fetch user info from Google", 500);
}
userInfo = await userInfoRes.json();
} catch (e) {
return c.text("Failed to fetch user info from Google", 500);
}
const { email, name, sub: login } = userInfo;
// Return back to the MCP client a new token
const { redirectTo } = await c.env.OAUTH_PROVIDER.completeAuthorization({
metadata: {
label: name,
},
// This will be available on this.props inside MyMCP
props: {
accessToken: access_token,
email,
login,
name,
idToken: id_token,
} as Props,
request: oauthReqInfo,
scope: oauthReqInfo.scope,
userId: login,
});
return Response.redirect(redirectTo);
});
export { app as GoogleHandler };
