Files
SRCmail/lib/oauth/discovery.ts
T

110 lines
4.0 KiB
TypeScript

export interface OAuthMetadata {
issuer: string;
authorization_endpoint: string;
token_endpoint: string;
revocation_endpoint?: string;
end_session_endpoint?: string;
}
// Validates that a discovered endpoint URL is safe to follow. Server-side
// callers must pass this to gate against SSRF (typically isPublicHttpUrl from
// @/lib/security/url-guard, which uses node:dns and cannot be bundled for the
// browser). Client callers omit it: the browser handles outbound networking
// and an SSRF check isn't meaningful there.
export type EndpointValidator = (url: string) => Promise<boolean>;
export interface DiscoverOAuthOptions {
validateEndpoint?: EndpointValidator;
}
const CACHE_TTL_MS = 10 * 60 * 1000;
const CACHE_MAX_ENTRIES = 64;
const metadataCache = new Map<string, { metadata: OAuthMetadata; expiresAt: number }>();
function rememberMetadata(serverUrl: string, metadata: OAuthMetadata): void {
// Bound the cache so callers that can supply arbitrary serverUrl values
// (e.g. unauthenticated routes that fall back to user input) cannot
// exhaust memory. Map preserves insertion order, so the oldest entry is
// always the first one yielded by keys().
if (metadataCache.size >= CACHE_MAX_ENTRIES) {
const oldest = metadataCache.keys().next().value;
if (oldest !== undefined) metadataCache.delete(oldest);
}
metadataCache.set(serverUrl, { metadata, expiresAt: Date.now() + CACHE_TTL_MS });
}
// Endpoints come from an attacker-controllable JSON document when callers pass
// a user-supplied serverUrl (e.g. /api/auth/totp-token-exchange under
// allowCustomJmapEndpoint). Without a validator, a malicious metadata document
// could point token_endpoint at 169.254.169.254 or 127.0.0.1:* and turn the
// downstream fetch() into an SSRF with response-body reflection. Server-side
// callers must pass `validateEndpoint`.
async function endpointsArePublic(
endpoints: Array<string | undefined>,
validate: EndpointValidator | undefined,
): Promise<boolean> {
if (!validate) return true;
for (const endpoint of endpoints) {
if (endpoint === undefined) continue;
if (typeof endpoint !== 'string') return false;
if (!(await validate(endpoint))) return false;
}
return true;
}
export async function discoverOAuth(
serverUrl: string,
options?: DiscoverOAuthOptions,
): Promise<OAuthMetadata | null> {
const cached = metadataCache.get(serverUrl);
if (cached && cached.expiresAt > Date.now()) return cached.metadata;
if (cached) metadataCache.delete(serverUrl);
const urls = [
`${serverUrl}/.well-known/oauth-authorization-server`,
`${serverUrl}/.well-known/openid-configuration`,
];
const errors: string[] = [];
for (const url of urls) {
try {
const response = await fetch(url);
if (!response.ok) {
errors.push(`${url} returned HTTP ${response.status}`);
continue;
}
const data = await response.json();
if (data.authorization_endpoint && data.token_endpoint) {
const allPublic = await endpointsArePublic([
data.authorization_endpoint,
data.token_endpoint,
data.revocation_endpoint,
data.end_session_endpoint,
], options?.validateEndpoint);
if (!allPublic) {
errors.push(`${url} returned non-public or invalid endpoint URL`);
continue;
}
const metadata: OAuthMetadata = {
issuer: data.issuer,
authorization_endpoint: data.authorization_endpoint,
token_endpoint: data.token_endpoint,
revocation_endpoint: data.revocation_endpoint,
end_session_endpoint: data.end_session_endpoint,
};
rememberMetadata(serverUrl, metadata);
return metadata;
}
errors.push(`${url} response missing required endpoints`);
} catch (err) {
errors.push(`${url}: ${err instanceof Error ? err.message : String(err)}`);
continue;
}
}
console.error(`[OAuth] Discovery failed for ${serverUrl}: ${errors.join('; ')}`);
return null;
}