125 lines
3.1 KiB
JavaScript
125 lines
3.1 KiB
JavaScript
'use strict'
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const assert = require('node:assert')
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/**
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* This takes care of revalidation requests we send to the origin. If we get
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* a response indicating that what we have is cached (via a HTTP 304), we can
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* continue using the cached value. Otherwise, we'll receive the new response
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* here, which we then just pass on to the next handler (most likely a
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* CacheHandler). Note that this assumes the proper headers were already
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* included in the request to tell the origin that we want to revalidate the
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* response (i.e. if-modified-since or if-none-match).
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*
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* @see https://www.rfc-editor.org/rfc/rfc9111.html#name-validation
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*
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* @implements {import('../../types/dispatcher.d.ts').default.DispatchHandler}
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*/
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class CacheRevalidationHandler {
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#successful = false
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/**
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* @type {((boolean, any) => void) | null}
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*/
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#callback
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/**
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* @type {(import('../../types/dispatcher.d.ts').default.DispatchHandler)}
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*/
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#handler
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#context
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/**
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* @type {boolean}
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*/
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#allowErrorStatusCodes
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/**
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* @param {(boolean) => void} callback Function to call if the cached value is valid
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* @param {import('../../types/dispatcher.d.ts').default.DispatchHandlers} handler
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* @param {boolean} allowErrorStatusCodes
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*/
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constructor (callback, handler, allowErrorStatusCodes) {
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if (typeof callback !== 'function') {
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throw new TypeError('callback must be a function')
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}
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this.#callback = callback
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this.#handler = handler
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this.#allowErrorStatusCodes = allowErrorStatusCodes
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}
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onRequestStart (_, context) {
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this.#successful = false
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this.#context = context
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}
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onRequestUpgrade (controller, statusCode, headers, socket) {
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this.#handler.onRequestUpgrade?.(controller, statusCode, headers, socket)
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}
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onResponseStart (
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controller,
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statusCode,
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headers,
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statusMessage
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) {
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assert(this.#callback != null)
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// https://www.rfc-editor.org/rfc/rfc9111.html#name-handling-a-validation-respo
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// https://datatracker.ietf.org/doc/html/rfc5861#section-4
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this.#successful = statusCode === 304 ||
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(this.#allowErrorStatusCodes && statusCode >= 500 && statusCode <= 504)
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this.#callback(this.#successful, this.#context)
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this.#callback = null
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if (this.#successful) {
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return true
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}
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this.#handler.onRequestStart?.(controller, this.#context)
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this.#handler.onResponseStart?.(
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controller,
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statusCode,
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headers,
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statusMessage
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)
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}
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onResponseData (controller, chunk) {
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if (this.#successful) {
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return
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}
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return this.#handler.onResponseData?.(controller, chunk)
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}
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onResponseEnd (controller, trailers) {
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if (this.#successful) {
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return
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}
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this.#handler.onResponseEnd?.(controller, trailers)
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}
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onResponseError (controller, err) {
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if (this.#successful) {
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return
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}
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if (this.#callback) {
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this.#callback(false)
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this.#callback = null
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}
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if (typeof this.#handler.onResponseError === 'function') {
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this.#handler.onResponseError(controller, err)
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} else {
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throw err
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}
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}
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}
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module.exports = CacheRevalidationHandler
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