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a2a-mcp/src/oauth.ts
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Coordinate a2amcp credential refresh
2026-06-01 09:51:45 -03:00

449 lines
13 KiB
TypeScript

import crypto from "node:crypto";
import { promises as fs } from "node:fs";
import http from "node:http";
import os from "node:os";
import path from "node:path";
import { spawn } from "node:child_process";
import type { AddressInfo } from "node:net";
import { ControlPlaneClient } from "./api.js";
import {
DEFAULT_API_URL,
type Credentials,
loadCredentials,
saveCredentials,
} from "./credentials.js";
export const DEFAULT_OAUTH_ISSUER = "https://auth.a2acloud.io/realms/a2acloud";
export const DEFAULT_OAUTH_CLIENT_ID = "a2acloud-cli";
export const DEFAULT_OAUTH_SCOPE = "openid email offline_access mcp:invoke agent:read";
export const DEFAULT_REDIRECT_PORT = 41873;
const CALLBACK_PATH = "/callback";
const REFRESH_LOCK_WAIT_MS = 10_000;
const REFRESH_LOCK_STALE_MS = 30_000;
const REFRESH_LOCK_POLL_MS = 100;
type OpenIdConfiguration = {
authorization_endpoint: string;
token_endpoint: string;
};
type TokenResponse = {
access_token?: string;
refresh_token?: string;
expires_in?: number;
scope?: string;
error?: string;
error_description?: string;
};
export type BrowserLoginOptions = {
apiUrl?: string;
issuer?: string;
clientId?: string;
scope?: string;
port?: number;
openBrowser?: boolean;
timeoutMs?: number;
onAuthorizationUrl?: (url: string) => void;
};
export async function loginWithBrowser(
opts: BrowserLoginOptions = {},
): Promise<Credentials> {
const apiUrl = (opts.apiUrl || DEFAULT_API_URL).replace(/\/+$/, "");
const issuer = (opts.issuer || DEFAULT_OAUTH_ISSUER).replace(/\/+$/, "");
const clientId = opts.clientId || DEFAULT_OAUTH_CLIENT_ID;
const scope = opts.scope || DEFAULT_OAUTH_SCOPE;
const cfg = await discoverOpenIdConfiguration(issuer);
const pkce = createPkcePair();
const state = randomUrlSafe(32);
const callback = await listenForCallback({
port: opts.port ?? DEFAULT_REDIRECT_PORT,
state,
timeoutMs: opts.timeoutMs ?? 180_000,
});
try {
const redirectUri = callback.redirectUri;
const authorizationUrl = buildAuthorizationUrl({
authorizationEndpoint: cfg.authorization_endpoint,
clientId,
redirectUri,
scope,
state,
codeChallenge: pkce.challenge,
});
opts.onAuthorizationUrl?.(authorizationUrl);
if (opts.openBrowser !== false) openBrowser(authorizationUrl);
const code = await callback.waitForCode;
const token = await exchangeAuthorizationCode({
tokenEndpoint: cfg.token_endpoint,
clientId,
redirectUri,
code,
codeVerifier: pkce.verifier,
});
const creds = await credentialsFromToken({
apiUrl,
token,
issuer,
clientId,
scope,
});
await saveCredentials(creds);
return creds;
} finally {
await callback.close();
}
}
export async function loginWithAccessToken(
token: string,
opts: {
apiUrl?: string;
issuer?: string;
clientId?: string;
scope?: string;
} = {},
): Promise<Credentials> {
const apiUrl = (opts.apiUrl || DEFAULT_API_URL).replace(/\/+$/, "");
const creds = await credentialsFromToken({
apiUrl,
token: { access_token: token },
issuer: opts.issuer,
clientId: opts.clientId,
scope: opts.scope,
});
await saveCredentials(creds);
return creds;
}
export async function refreshCredentialsIfNeeded(
creds: Credentials,
minTtlSeconds = 60,
): Promise<Credentials> {
if (!creds.refreshToken || !creds.issuer || !creds.clientId) return creds;
if (credentialsFresh(creds, minTtlSeconds)) return creds;
return withRefreshLock(async () => {
const latest = await loadCredentials();
if (latest && sameOAuthClient(latest, creds)) {
if (credentialsFresh(latest, minTtlSeconds)) return latest;
if (latest.refreshToken && latest.issuer && latest.clientId) creds = latest;
}
return refreshCredentials(creds);
});
}
async function refreshCredentials(creds: Credentials): Promise<Credentials> {
const cfg = await discoverOpenIdConfiguration(creds.issuer!);
const body = new URLSearchParams({
grant_type: "refresh_token",
client_id: creds.clientId!,
refresh_token: creds.refreshToken!,
});
const resp = await fetch(cfg.token_endpoint, {
method: "POST",
headers: { "content-type": "application/x-www-form-urlencoded" },
body,
});
let token: TokenResponse;
try {
token = await parseTokenResponse(resp);
} catch (err) {
const detail = err instanceof Error ? err.message : String(err);
throw new Error(
`Login expired or revoked. Run \`a2amcp login\` and retry. (${detail})`,
);
}
const next: Credentials = {
...creds,
token: token.access_token!,
refreshToken: token.refresh_token || creds.refreshToken,
expiresAt: expiresAt(token.expires_in),
scope: token.scope || creds.scope,
};
await saveCredentials(next);
return next;
}
function credentialsFresh(creds: Credentials, minTtlSeconds: number): boolean {
return Boolean(creds.expiresAt && creds.expiresAt - nowSeconds() > minTtlSeconds);
}
function sameOAuthClient(a: Credentials, b: Credentials): boolean {
return (
a.apiUrl === b.apiUrl &&
a.issuer === b.issuer &&
a.clientId === b.clientId
);
}
async function withRefreshLock<T>(fn: () => Promise<T>): Promise<T> {
const release = await acquireRefreshLock();
try {
return await fn();
} finally {
await release();
}
}
async function acquireRefreshLock(): Promise<() => Promise<void>> {
const file = refreshLockFile();
await fs.mkdir(path.dirname(file), { recursive: true });
const started = Date.now();
while (true) {
try {
const handle = await fs.open(file, "wx", 0o600);
try {
await handle.writeFile(
JSON.stringify({ pid: process.pid, created_at: new Date().toISOString() }),
);
} finally {
await handle.close();
}
return async () => {
try {
await fs.unlink(file);
} catch (err: any) {
if (err?.code !== "ENOENT") throw err;
}
};
} catch (err: any) {
if (err?.code !== "EEXIST") throw err;
await removeStaleRefreshLock(file);
if (Date.now() - started > REFRESH_LOCK_WAIT_MS) {
throw new Error("timed out waiting for credential refresh lock");
}
await sleep(REFRESH_LOCK_POLL_MS);
}
}
}
async function removeStaleRefreshLock(file: string): Promise<void> {
try {
const stat = await fs.stat(file);
if (Date.now() - stat.mtimeMs <= REFRESH_LOCK_STALE_MS) return;
await fs.unlink(file);
} catch (err: any) {
if (err?.code !== "ENOENT") throw err;
}
}
function refreshLockFile(): string {
return path.join(os.homedir(), ".a2a", "credentials-refresh.lock");
}
export async function discoverOpenIdConfiguration(
issuer: string,
): Promise<OpenIdConfiguration> {
const url = `${issuer.replace(/\/+$/, "")}/.well-known/openid-configuration`;
const resp = await fetch(url, { headers: { accept: "application/json" } });
if (!resp.ok) throw new Error(`OpenID discovery failed: ${resp.status}`);
const data = (await resp.json()) as Partial<OpenIdConfiguration>;
if (!data.authorization_endpoint || !data.token_endpoint) {
throw new Error("OpenID discovery document is missing authorization/token endpoints");
}
return {
authorization_endpoint: data.authorization_endpoint,
token_endpoint: data.token_endpoint,
};
}
export function createPkcePair(): { verifier: string; challenge: string } {
const verifier = randomUrlSafe(64);
const challenge = crypto
.createHash("sha256")
.update(verifier)
.digest("base64url");
return { verifier, challenge };
}
export function buildAuthorizationUrl(opts: {
authorizationEndpoint: string;
clientId: string;
redirectUri: string;
scope: string;
state: string;
codeChallenge: string;
}): string {
const url = new URL(opts.authorizationEndpoint);
url.searchParams.set("client_id", opts.clientId);
url.searchParams.set("redirect_uri", opts.redirectUri);
url.searchParams.set("response_type", "code");
url.searchParams.set("scope", opts.scope);
url.searchParams.set("state", opts.state);
url.searchParams.set("code_challenge", opts.codeChallenge);
url.searchParams.set("code_challenge_method", "S256");
return url.toString();
}
async function exchangeAuthorizationCode(opts: {
tokenEndpoint: string;
clientId: string;
redirectUri: string;
code: string;
codeVerifier: string;
}): Promise<TokenResponse> {
const body = new URLSearchParams({
grant_type: "authorization_code",
client_id: opts.clientId,
redirect_uri: opts.redirectUri,
code: opts.code,
code_verifier: opts.codeVerifier,
});
const resp = await fetch(opts.tokenEndpoint, {
method: "POST",
headers: { "content-type": "application/x-www-form-urlencoded" },
body,
});
return parseTokenResponse(resp);
}
async function parseTokenResponse(resp: Response): Promise<TokenResponse> {
const text = await resp.text();
const data = parseJsonObject(text) as TokenResponse;
if (!resp.ok || !data.access_token) {
const message = data.error_description || data.error || text.trim() || resp.statusText;
throw new Error(`Keycloak token exchange failed: ${message}`);
}
return data;
}
async function credentialsFromToken(opts: {
apiUrl: string;
token: TokenResponse;
issuer?: string;
clientId?: string;
scope?: string;
}): Promise<Credentials> {
const me = await new ControlPlaneClient(opts.apiUrl, opts.token.access_token!).me();
return {
apiUrl: opts.apiUrl,
token: opts.token.access_token!,
email: me.email,
userId: me.id,
bucket: `user-${me.id}-files`,
refreshToken: opts.token.refresh_token,
expiresAt: expiresAt(opts.token.expires_in),
issuer: opts.issuer,
clientId: opts.clientId,
scope: opts.token.scope || opts.scope,
};
}
function listenForCallback(opts: {
port: number;
state: string;
timeoutMs: number;
}): Promise<{
redirectUri: string;
waitForCode: Promise<string>;
close: () => Promise<void>;
}> {
let resolveCode!: (code: string) => void;
let rejectCode!: (err: Error) => void;
const waitForCode = new Promise<string>((resolve, reject) => {
resolveCode = resolve;
rejectCode = reject;
});
const server = http.createServer((req, res) => {
const url = new URL(req.url || "/", `http://${req.headers.host}`);
if (url.pathname !== CALLBACK_PATH) {
res.statusCode = 404;
res.end("not found");
return;
}
const error = url.searchParams.get("error");
const errorDescription = url.searchParams.get("error_description");
const code = url.searchParams.get("code");
const state = url.searchParams.get("state");
if (error) {
rejectCode(new Error(errorDescription || error));
finishBrowser(res, false);
return;
}
if (!code || state !== opts.state) {
rejectCode(new Error("invalid OAuth callback"));
finishBrowser(res, false);
return;
}
resolveCode(code);
finishBrowser(res, true);
});
const timer = setTimeout(() => {
rejectCode(new Error("timed out waiting for Keycloak login"));
}, opts.timeoutMs);
return new Promise((resolve, reject) => {
server.on("error", reject);
server.listen(opts.port, "127.0.0.1", () => {
const { port } = server.address() as AddressInfo;
resolve({
redirectUri: `http://127.0.0.1:${port}${CALLBACK_PATH}`,
waitForCode,
close: () =>
new Promise((done) => {
clearTimeout(timer);
server.close(() => done());
}),
});
});
});
}
function finishBrowser(res: http.ServerResponse, ok: boolean): void {
res.statusCode = ok ? 200 : 400;
res.setHeader("content-type", "text/html; charset=utf-8");
res.end(
`<html><body><h1>${ok ? "a2amcp is connected" : "a2amcp login failed"}</h1>` +
"<p>You can close this tab and return to your terminal.</p></body></html>",
);
}
function openBrowser(url: string): void {
const cmd =
process.platform === "darwin"
? "open"
: process.platform === "win32"
? "cmd"
: "xdg-open";
const args =
process.platform === "win32"
? ["/c", "start", "", url]
: [url];
const child = spawn(cmd, args, { detached: true, stdio: "ignore" });
child.on("error", () => {});
child.unref();
}
function randomUrlSafe(bytes: number): string {
return crypto.randomBytes(bytes).toString("base64url");
}
function expiresAt(expiresIn: number | undefined): number | undefined {
return typeof expiresIn === "number" ? nowSeconds() + expiresIn : undefined;
}
function nowSeconds(): number {
return Math.floor(Date.now() / 1000);
}
function sleep(ms: number): Promise<void> {
return new Promise((resolve) => setTimeout(resolve, ms));
}
function parseJsonObject(text: string): Record<string, unknown> {
if (!text.trim()) return {};
try {
const parsed = JSON.parse(text);
return parsed && typeof parsed === "object" ? parsed : {};
} catch {
return {};
}
}