121 lines
3.1 KiB
JavaScript
121 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(controller, statusCode, headers, statusMessage) {
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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 =
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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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