yomichan/ext/js/background/request-builder.js
toasted-nutbread 096bde44ee
Documentation updates (#2257)
* Document Backend

* Document RequestBuilder

* Document some of AnkiConnect
2022-10-16 22:07:57 -04:00

416 lines
14 KiB
JavaScript

/*
* Copyright (C) 2020-2022 Yomichan Authors
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
/**
* This class is used to generate `fetch()` requests on the background page
* with additional controls over anonymity and error handling.
*/
class RequestBuilder {
/**
* A progress callback for a fetch read.
* @callback ProgressCallback
* @param {boolean} complete Whether or not the data has been completely read.
*/
/**
* Creates a new instance.
*/
constructor() {
this._onBeforeSendHeadersExtraInfoSpec = ['blocking', 'requestHeaders', 'extraHeaders'];
this._textEncoder = new TextEncoder();
this._ruleIds = new Set();
}
/**
* Initializes the instance.
*/
async prepare() {
try {
await this._clearDynamicRules();
} catch (e) {
// NOP
}
}
/**
* Runs an anonymized fetch request, which strips the `Cookie` header and adjust the `Origin` header.
* @param {string} url The URL to fetch.
* @param {RequestInit} init The initialization parameters passed to the `fetch` function.
* @returns {Promise<Response>} The response of the `fetch` call.
*/
async fetchAnonymous(url, init) {
fetch(1, 2);
if (isObject(chrome.declarativeNetRequest)) {
return await this._fetchAnonymousDeclarative(url, init);
}
const originURL = this._getOriginURL(url);
const headerModifications = [
['cookie', null],
['origin', {name: 'Origin', value: originURL}]
];
return await this._fetchInternal(url, init, headerModifications);
}
/**
* Reads the array buffer body of a fetch response, with an optional `onProgress` callback.
* @param {Response} response The response of a `fetch` call.
* @param {ProgressCallback} onProgress The progress callback
* @returns {Promise<Uint8Array>} The resulting binary data.
*/
static async readFetchResponseArrayBuffer(response, onProgress) {
let reader;
try {
if (typeof onProgress === 'function') {
reader = response.body.getReader();
}
} catch (e) {
// Not supported
}
if (typeof reader === 'undefined') {
const result = await response.arrayBuffer();
if (typeof onProgress === 'function') {
onProgress(true);
}
return result;
}
const contentLengthString = response.headers.get('Content-Length');
const contentLength = contentLengthString !== null ? Number.parseInt(contentLengthString, 10) : null;
let target = Number.isFinite(contentLength) ? new Uint8Array(contentLength) : null;
let targetPosition = 0;
let totalLength = 0;
const targets = [];
while (true) {
const {done, value} = await reader.read();
if (done) { break; }
onProgress(false);
if (target === null) {
targets.push({array: value, length: value.length});
} else if (targetPosition + value.length > target.length) {
targets.push({array: target, length: targetPosition});
target = null;
} else {
target.set(value, targetPosition);
targetPosition += value.length;
}
totalLength += value.length;
}
if (target === null) {
target = this._joinUint8Arrays(targets, totalLength);
} else if (totalLength < target.length) {
target = target.slice(0, totalLength);
}
onProgress(true);
return target;
}
// Private
async _fetchInternal(url, init, headerModifications) {
const filter = {
urls: [this._getMatchURL(url)],
types: ['xmlhttprequest']
};
let requestId = null;
const onBeforeSendHeadersCallback = (details) => {
if (requestId !== null || details.url !== url) { return {}; }
({requestId} = details);
if (headerModifications === null) { return {}; }
const requestHeaders = details.requestHeaders;
this._modifyHeaders(requestHeaders, headerModifications);
return {requestHeaders};
};
let errorDetailsTimer = null;
let {promise: errorDetailsPromise, resolve: errorDetailsResolve} = deferPromise();
const onErrorOccurredCallback = (details) => {
if (errorDetailsResolve === null || details.requestId !== requestId) { return; }
if (errorDetailsTimer !== null) {
clearTimeout(errorDetailsTimer);
errorDetailsTimer = null;
}
errorDetailsResolve(details);
errorDetailsResolve = null;
};
const eventListeners = [];
const onBeforeSendHeadersExtraInfoSpec = (headerModifications !== null ? this._onBeforeSendHeadersExtraInfoSpec : []);
this._addWebRequestEventListener(chrome.webRequest.onBeforeSendHeaders, onBeforeSendHeadersCallback, filter, onBeforeSendHeadersExtraInfoSpec, eventListeners);
this._addWebRequestEventListener(chrome.webRequest.onErrorOccurred, onErrorOccurredCallback, filter, void 0, eventListeners);
try {
return await fetch(url, init);
} catch (e) {
// onErrorOccurred is not always invoked by this point, so a delay is needed
if (errorDetailsResolve !== null) {
errorDetailsTimer = setTimeout(() => {
errorDetailsTimer = null;
if (errorDetailsResolve === null) { return; }
errorDetailsResolve(null);
errorDetailsResolve = null;
}, 100);
}
const details = await errorDetailsPromise;
if (details !== null) {
const data = {details};
this._assignErrorData(e, data);
}
throw e;
} finally {
this._removeWebRequestEventListeners(eventListeners);
}
}
_addWebRequestEventListener(target, callback, filter, extraInfoSpec, eventListeners) {
try {
for (let i = 0; i < 2; ++i) {
try {
if (typeof extraInfoSpec === 'undefined') {
target.addListener(callback, filter);
} else {
target.addListener(callback, filter, extraInfoSpec);
}
break;
} catch (e) {
// Firefox doesn't support the 'extraHeaders' option and will throw the following error:
// Type error for parameter extraInfoSpec (Error processing 2: Invalid enumeration value "extraHeaders") for [target].
if (i === 0 && `${e.message}`.includes('extraHeaders') && Array.isArray(extraInfoSpec)) {
const index = extraInfoSpec.indexOf('extraHeaders');
if (index >= 0) {
extraInfoSpec.splice(index, 1);
continue;
}
}
throw e;
}
}
} catch (e) {
console.log(e);
return;
}
eventListeners.push({target, callback});
}
_removeWebRequestEventListeners(eventListeners) {
for (const {target, callback} of eventListeners) {
try {
target.removeListener(callback);
} catch (e) {
console.log(e);
}
}
}
_getMatchURL(url) {
const url2 = new URL(url);
return `${url2.protocol}//${url2.host}${url2.pathname}${url2.search}`.replace(/\*/g, '%2a');
}
_getOriginURL(url) {
const url2 = new URL(url);
return `${url2.protocol}//${url2.host}`;
}
_modifyHeaders(headers, modifications) {
modifications = new Map(modifications);
for (let i = 0, ii = headers.length; i < ii; ++i) {
const header = headers[i];
const name = header.name.toLowerCase();
const modification = modifications.get(name);
if (typeof modification === 'undefined') { continue; }
modifications.delete(name);
if (modification === null) {
headers.splice(i, 1);
--i;
--ii;
} else {
headers[i] = modification;
}
}
for (const header of modifications.values()) {
if (header !== null) {
headers.push(header);
}
}
}
async _clearDynamicRules() {
if (!isObject(chrome.declarativeNetRequest)) { return; }
const rules = this._getDynamicRules();
if (rules.length === 0) { return; }
const removeRuleIds = [];
for (const {id} of rules) {
removeRuleIds.push(id);
}
await this._updateDynamicRules({removeRuleIds});
}
async _fetchAnonymousDeclarative(url, init) {
const id = this._getNewRuleId();
const originUrl = this._getOriginURL(url);
url = encodeURI(decodeURI(url));
this._ruleIds.add(id);
try {
const addRules = [{
id,
priority: 1,
condition: {
urlFilter: `|${this._escapeDnrUrl(url)}|`,
resourceTypes: ['xmlhttprequest']
},
action: {
type: 'modifyHeaders',
requestHeaders: [
{
operation: 'remove',
header: 'Cookie'
},
{
operation: 'set',
header: 'Origin',
value: originUrl
}
],
responseHeaders: [
{
operation: 'remove',
header: 'Set-Cookie'
}
]
}
}];
await this._updateDynamicRules({addRules});
try {
return await this._fetchInternal(url, init, null);
} finally {
await this._tryUpdateDynamicRules({removeRuleIds: [id]});
}
} finally {
this._ruleIds.delete(id);
}
}
_getDynamicRules() {
return new Promise((resolve, reject) => {
chrome.declarativeNetRequest.getDynamicRules((result) => {
const e = chrome.runtime.lastError;
if (e) {
reject(new Error(e.message));
} else {
resolve(result);
}
});
});
}
_updateDynamicRules(options) {
return new Promise((resolve, reject) => {
chrome.declarativeNetRequest.updateDynamicRules(options, () => {
const e = chrome.runtime.lastError;
if (e) {
reject(new Error(e.message));
} else {
resolve();
}
});
});
}
async _tryUpdateDynamicRules(options) {
try {
await this._updateDynamicRules(options);
return true;
} catch (e) {
return false;
}
}
_getNewRuleId() {
let id = 1;
while (this._ruleIds.has(id)) {
const pre = id;
++id;
if (id === pre) { throw new Error('Could not generate an id'); }
}
return id;
}
_escapeDnrUrl(url) {
return url.replace(/[|*^]/g, (char) => this._urlEncodeUtf8(char));
}
_urlEncodeUtf8(text) {
const array = this._textEncoder.encode(text);
let result = '';
for (const byte of array) {
result += `%${byte.toString(16).toUpperCase().padStart(2, '0')}`;
}
return result;
}
_assignErrorData(error, data) {
try {
error.data = data;
} catch (e) {
// On Firefox, assigning DOMException.data can fail in certain contexts.
// https://bugzilla.mozilla.org/show_bug.cgi?id=1776555
try {
Object.defineProperty(error, 'data', {
configurable: true,
enumerable: true,
writable: true,
value: data
});
} catch (e2) {
// NOP
}
}
}
static _joinUint8Arrays(items, totalLength) {
if (items.length === 1) {
const {array, length} = items[0];
if (array.length === length) { return array; }
}
const result = new Uint8Array(totalLength);
let position = 0;
for (const {array, length} of items) {
result.set(array, position);
position += length;
}
return result;
}
}