Jakub Zych
0a01bfeae4
- privateRevalidate sets max-age=0 on cache-control values with s-maxage - server/plugins/journal-revalidate.ts wraps res.setHeader per request, so Nitro's 200 and h3's 304 answers both carry it - purge-check: max-age=0 on 200 and 304, purged _payload.json, a second purge after re-caching, X-Real-IP refused, 404 on a server without a token - README: cachePurgeToken row and a Site cache purge section
101 lines
4.0 KiB
TypeScript
101 lines
4.0 KiB
TypeScript
// Site cache purge: the authorization rules of the purge route, the purge of
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// Nitro's route cache and the parsing of the purge request body. Pure
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// TypeScript, so `node --test` and the server route both import it directly.
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import { createHash, timingSafeEqual } from 'node:crypto'
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/** The shortest purge token the route accepts; with a shorter one it is off. */
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export const MIN_PURGE_TOKEN_LENGTH = 32
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/** The cache storage base of Nitro's route cache (routeRules cache and swr). */
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export const ROUTE_CACHE_BASE = 'nitro:routes'
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/** Longest slug the purge log line carries. */
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const MAX_SLUG_LENGTH = 200
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export type PurgeVerdict = 'ok' | 'disabled' | 'proxied' | 'unauthorized'
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export interface PurgeAuthInput {
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/** The configured token (runtimeConfig.journal.cachePurgeToken). */
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token: unknown
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/** The request's Authorization header, if any. */
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authorization?: string | null
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/** True when the request carried X-Forwarded-For, X-Real-IP or Forwarded. */
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proxied: boolean
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}
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function digest(value: string): Buffer {
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return createHash('sha256').update(value, 'utf8').digest()
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}
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/**
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* Decides a purge request: `disabled` when no token of at least
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* MIN_PURGE_TOKEN_LENGTH characters is configured, `proxied` when the
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* request came through a reverse proxy (checked before the token), `ok` when
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* the Bearer value equals the token (compared in constant time over sha256
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* digests) and `unauthorized` otherwise.
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*/
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export function authorizePurge({ token, authorization, proxied }: PurgeAuthInput): PurgeVerdict {
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if (typeof token !== 'string' || token.length < MIN_PURGE_TOKEN_LENGTH) return 'disabled'
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if (proxied) return 'proxied'
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const m = /^Bearer[ \t]+(\S+)[ \t]*$/i.exec(authorization ?? '')
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if (!m) return 'unauthorized'
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return timingSafeEqual(digest(m[1]), digest(token)) ? 'ok' : 'unauthorized'
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}
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/** The part of a Nitro/unstorage storage the purge uses. */
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export interface PurgeStorage {
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getKeys(base?: string): Promise<string[]> | string[]
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removeItem(key: string): Promise<unknown> | unknown
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}
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/**
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* Removes every entry of Nitro's route cache (pages, their _payload.json and
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* feeds) from storage, which is `useStorage('cache')`, and returns how many
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* it removed. Other cache groups (cached functions, handlers) stay.
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*/
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export async function purgeRouteCache(storage: PurgeStorage): Promise<number> {
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const keys = await storage.getKeys(ROUTE_CACHE_BASE)
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let removed = 0
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for (const key of keys) {
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if (!key.startsWith(ROUTE_CACHE_BASE + ':')) continue
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await storage.removeItem(key)
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removed++
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}
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return removed
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}
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export interface PurgeEvent {
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kind: 'post' | 'category' | 'unknown'
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slug: string
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}
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/**
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* Reads the kind and slug of a purge request body for the log line: kind is
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* post, category or unknown; the slug loses control characters and is cut
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* to 200 characters.
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*/
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export function parsePurgeEvent(body: unknown): PurgeEvent {
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if (body === null || typeof body !== 'object' || Array.isArray(body)) return { kind: 'unknown', slug: '' }
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const raw = body as Record<string, unknown>
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const kind = raw.kind === 'post' || raw.kind === 'category' ? raw.kind : 'unknown'
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// eslint-disable-next-line no-control-regex
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const slug = typeof raw.slug === 'string' ? raw.slug.replace(/[\u0000-\u001f\u007f-\u009f]/g, '').slice(0, MAX_SLUG_LENGTH) : ''
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return { kind, slug }
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}
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/**
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* Makes browsers revalidate a shared-cache response: for a cache-control
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* value that carries s-maxage it sets max-age=0, replacing any max-age=<n>
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* or prepending it, and keeps every other directive (shared caches keep
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* s-maxage). Other values, such as a static asset's
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* "public, max-age=31536000, immutable", are returned unchanged.
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*/
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export function privateRevalidate(cacheControl: string): string {
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if (typeof cacheControl !== 'string' || !/(^|[\s,])s-maxage\s*=/i.test(cacheControl)) return cacheControl
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if (/(^|[\s,])max-age\s*=\s*\d*/i.test(cacheControl)) {
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return cacheControl.replace(/(^|[\s,])max-age\s*=\s*\d*/i, '$1max-age=0')
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}
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return `max-age=0, ${cacheControl}`
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}
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