'use strict';
// See https://github.com/facebook/jest/issues/2549
// eslint-disable-next-line node/prefer-global/url
const {URL} = require('url');
const EventEmitter = require('events');
const tls = require('tls');
const http2 = require('http2');
const QuickLRU = require('quick-lru');
const delayAsyncDestroy = require('./utils/delay-async-destroy.js');
const kCurrentStreamCount = Symbol('currentStreamCount');
const kRequest = Symbol('request');
const kOriginSet = Symbol('cachedOriginSet');
const kGracefullyClosing = Symbol('gracefullyClosing');
const kLength = Symbol('length');
const nameKeys = [
// Not an Agent option actually
'createConnection',
// `http2.connect()` options
'maxDeflateDynamicTableSize',
'maxSettings',
'maxSessionMemory',
'maxHeaderListPairs',
'maxOutstandingPings',
'maxReservedRemoteStreams',
'maxSendHeaderBlockLength',
'paddingStrategy',
'peerMaxConcurrentStreams',
'settings',
// `tls.connect()` source options
'family',
'localAddress',
'rejectUnauthorized',
// `tls.connect()` secure context options
'pskCallback',
'minDHSize',
// `tls.connect()` destination options
// - `servername` is automatically validated, skip it
// - `host` and `port` just describe the destination server,
'path',
'socket',
// `tls.createSecureContext()` options
'ca',
'cert',
'sigalgs',
'ciphers',
'clientCertEngine',
'crl',
'dhparam',
'ecdhCurve',
'honorCipherOrder',
'key',
'privateKeyEngine',
'privateKeyIdentifier',
'maxVersion',
'minVersion',
'pfx',
'secureOptions',
'secureProtocol',
'sessionIdContext',
'ticketKeys'
];
const getSortedIndex = (array, value, compare) => {
let low = 0;
let high = array.length;
while (low < high) {
const mid = (low + high) >>> 1;
if (compare(array[mid], value)) {
low = mid + 1;
} else {
high = mid;
}
}
return low;
};
const compareSessions = (a, b) => a.remoteSettings.maxConcurrentStreams > b.remoteSettings.maxConcurrentStreams;
// See https://tools.ietf.org/html/rfc8336
const closeCoveredSessions = (where, session) => {
// Clients SHOULD NOT emit new requests on any connection whose Origin
// Set is a proper subset of another connection's Origin Set, and they
// SHOULD close it once all outstanding requests are satisfied.
for (let index = 0; index < where.length; index++) {
const coveredSession = where[index];
if (
// Unfortunately `.every()` returns true for an empty array
coveredSession[kOriginSet].length > 0
// The set is a proper subset when its length is less than the other set.
&& coveredSession[kOriginSet].length < session[kOriginSet].length
// And the other set includes all elements of the subset.
&& coveredSession[kOriginSet].every(origin => session[kOriginSet].includes(origin))
// Makes sure that the session can handle all requests from the covered session.
&& (coveredSession[kCurrentStreamCount] + session[kCurrentStreamCount]) <= session.remoteSettings.maxConcurrentStreams
) {
// This allows pending requests to finish and prevents making new requests.
gracefullyClose(coveredSession);
}
}
};
// This is basically inverted `closeCoveredSessions(...)`.
const closeSessionIfCovered = (where, coveredSession) => {
for (let index = 0; index < where.length; index++) {
const session = where[index];
if (
coveredSession[kOriginSet].length > 0
&& coveredSession[kOriginSet].length < session[kOriginSet].length
&& coveredSession[kOriginSet].every(origin => session[kOriginSet].includes(origin))
&& (coveredSession[kCurrentStreamCount] + session[kCurrentStreamCount]) <= session.remoteSettings.maxConcurrentStreams
) {
gracefullyClose(coveredSession);
return true;
}
}
return false;
};
const gracefullyClose = session => {
session[kGracefullyClosing] = true;
if (session[kCurrentStreamCount] === 0) {
session.close();
}
};
class Agent extends EventEmitter {
constructor({timeout = 0, maxSessions = Number.POSITIVE_INFINITY, maxEmptySessions = 10, maxCachedTlsSessions = 100} = {}) {
super();
// SESSIONS[NORMALIZED_OPTIONS] = [];
this.sessions = {};
// The queue for creating new sessions. It looks like this:
// QUEUE[NORMALIZED_OPTIONS][NORMALIZED_ORIGIN] = ENTRY_FUNCTION
//
// It's faster when there are many origins. If there's only one, then QUEUE[`${options}:${origin}`] is faster.
// I guess object creation / deletion is causing the slowdown.
//
// The entry function has `listeners`, `completed` and `destroyed` properties.
// `listeners` is an array of objects containing `resolve` and `reject` functions.
// `completed` is a boolean. It's set to true after ENTRY_FUNCTION is executed.
// `destroyed` is a boolean. If it's set to true, the session will be destroyed if hasn't connected yet.
this.queue = {};
// Each session will use this timeout value.
this.timeout = timeout;
// Max sessions in total
this.maxSessions = maxSessions;
// Max empty sessions in total
this.maxEmptySessions = maxEmptySessions;
this._emptySessionCount = 0;
this._sessionCount = 0;
// We don't support push streams by default.
this.settings = {
enablePush: false,
initialWindowSize: 1024 * 1024 * 32 // 32MB, see https://github.com/nodejs/node/issues/38426
};
// Reusing TLS sessions increases performance.
this.tlsSessionCache = new QuickLRU({maxSize: maxCachedTlsSessions});
}
get protocol() {
return 'https:';
}
normalizeOptions(options) {
let normalized = '';
for (let index = 0; index < nameKeys.length; index++) {
const key = nameKeys[index];
normalized += ':';
if (options && options[key] !== undefined) {
normalized += options[key];
}
}
return normalized;
}
_processQueue() {
if (this._sessionCount >= this.maxSessions) {
this.closeEmptySessions(this.maxSessions - this._sessionCount + 1);
return;
}
// eslint-disable-next-line guard-for-in
for (const normalizedOptions in this.queue) {
// eslint-disable-next-line guard-for-in
for (const normalizedOrigin in this.queue[normalizedOptions]) {
const item = this.queue[normalizedOptions][normalizedOrigin];
// The entry function can be run only once.
if (!item.completed) {
item.completed = true;
item();
}
}
}
}
_isBetterSession(thisStreamCount, thatStreamCount) {
return thisStreamCount > thatStreamCount;
}
_accept(session, listeners, normalizedOrigin, options) {
let index = 0;
while (index < listeners.length && session[kCurrentStreamCount] < session.remoteSettings.maxConcurrentStreams) {
// We assume `resolve(...)` calls `request(...)` *directly*,
// otherwise the session will get overloaded.
listeners[index].resolve(session);
index++;
}
listeners.splice(0, index);
if (listeners.length > 0) {
this.getSession(normalizedOrigin, options, listeners);
listeners.length = 0;
}
}
getSession(origin, options, listeners) {
return new Promise((resolve, reject) => {
if (Array.isArray(listeners) && listeners.length > 0) {
listeners = [...listeners];
// Resolve the current promise ASAP, we're just moving the listeners.
// They will be executed at a different time.
resolve();
} else {
listeners = [{resolve, reject}];
}
try {
// Parse origin
if (typeof origin === 'string') {
origin = new URL(origin);
} else if (!(origin instanceof URL)) {
throw new TypeError('The `origin` argument needs to be a string or an URL object');
}
if (options) {
// Validate servername
const {servername} = options;
const {hostname} = origin;
if (servername && hostname !== servername) {
throw new Error(`Origin ${hostname} differs from servername ${servername}`);
}
}
} catch (error) {
for (let index = 0; index < listeners.length; index++) {
listeners[index].reject(error);
}
return;
}
const normalizedOptions = this.normalizeOptions(options);
const normalizedOrigin = origin.origin;
if (normalizedOptions in this.sessions) {
const sessions = this.sessions[normalizedOptions];
let maxConcurrentStreams = -1;
let currentStreamsCount = -1;
let optimalSession;
// We could just do this.sessions[normalizedOptions].find(...) but that isn't optimal.
// Additionally, we are looking for session which has biggest current pending streams count.
//
// |------------| |------------| |------------| |------------|
// | Session: A | | Session: B | | Session: C | | Session: D |
// | Pending: 5 |-| Pending: 8 |-| Pending: 9 |-| Pending: 4 |
// | Max: 10 | | Max: 10 | | Max: 9 | | Max: 5 |
// |------------| |------------| |------------| |------------|
// ^
// |
// pick this one --
//
for (let index = 0; index < sessions.length; index++) {
const session = sessions[index];
const sessionMaxConcurrentStreams = session.remoteSettings.maxConcurrentStreams;
if (sessionMaxConcurrentStreams < maxConcurrentStreams) {
break;
}
if (!session[kOriginSet].includes(normalizedOrigin)) {
continue;
}
const sessionCurrentStreamsCount = session[kCurrentStreamCount];
if (
sessionCurrentStreamsCount >= sessionMaxConcurrentStreams
|| session[kGracefullyClosing]
// Unfortunately the `close` event isn't called immediately,
// so `session.destroyed` is `true`, but `session.closed` is `false`.
|| session.destroyed
) {
continue;
}
// We only need set this once.
if (!optimalSession) {
maxConcurrentStreams = sessionMaxConcurrentStreams;
}
// Either get the session which has biggest current stream count or the lowest.
if (this._isBetterSession(sessionCurrentStreamsCount, currentStreamsCount)) {
optimalSession = session;
currentStreamsCount = sessionCurrentStreamsCount;
}
}
if (optimalSession) {
this._accept(optimalSession, listeners, normalizedOrigin, options);
return;
}
}
if (normalizedOptions in this.queue) {
if (normalizedOrigin in this.queue[normalizedOptions]) {
// There's already an item in the queue, just attach ourselves to it.
this.queue[normalizedOptions][normalizedOrigin].listeners.push(...listeners);
return;
}
} else {
this.queue[normalizedOptions] = {
[kLength]: 0
};
}
// The entry must be removed from the queue IMMEDIATELY when:
// 1. the session connects successfully,
// 2. an error occurs.
const removeFromQueue = () => {
// Our entry can be replaced. We cannot remove the new one.
if (normalizedOptions in this.queue && this.queue[normalizedOptions][normalizedOrigin] === entry) {
delete this.queue[normalizedOptions][normalizedOrigin];
if (--this.queue[normalizedOptions][kLength] === 0) {
delete this.queue[normalizedOptions];
}
}
};
// The main logic is here
const entry = async () => {
this._sessionCount++;
const name = `${normalizedOrigin}:${normalizedOptions}`;
let receivedSettings = false;
let socket;
try {
const computedOptions = {...options};
if (computedOptions.settings === undefined) {
computedOptions.settings = this.settings;
}
if (computedOptions.session === undefined) {
computedOptions.session = this.tlsSessionCache.get(name);
}
const createConnection = computedOptions.createConnection || this.createConnection;
// A hacky workaround to enable async `createConnection`
socket = await createConnection.call(this, origin, computedOptions);
computedOptions.createConnection = () => socket;
const session = http2.connect(origin, computedOptions);
session[kCurrentStreamCount] = 0;
session[kGracefullyClosing] = false;
// Node.js return https://false:443 instead of https://1.1.1.1:443
const getOriginSet = () => {
const {socket} = session;
let originSet;
if (socket.servername === false) {
socket.servername = socket.remoteAddress;
originSet = session.originSet;
socket.servername = false;
} else {
originSet = session.originSet;
}
return originSet;
};
const isFree = () => session[kCurrentStreamCount] < session.remoteSettings.maxConcurrentStreams;
session.socket.once('session', tlsSession => {
this.tlsSessionCache.set(name, tlsSession);
});
session.once('error', error => {
// Listeners are empty when the session successfully connected.
for (let index = 0; index < listeners.length; index++) {
listeners[index].reject(error);
}
// The connection got broken, purge the cache.
this.tlsSessionCache.delete(name);
});
session.setTimeout(this.timeout, () => {
// Terminates all streams owned by this session.
session.destroy();
});
session.once('close', () => {
this._sessionCount--;
if (receivedSettings) {
// Assumes session `close` is emitted after request `close`
this._emptySessionCount--;
// This cannot be moved to the stream logic,
// because there may be a session that hadn't made a single request.
const where = this.sessions[normalizedOptions];
if (where.length === 1) {
delete this.sessions[normalizedOptions];
} else {
where.splice(where.indexOf(session), 1);
}
} else {
// Broken connection
removeFromQueue();
const error = new Error('Session closed without receiving a SETTINGS frame');
error.code = 'HTTP2WRAPPER_NOSETTINGS';
for (let index = 0; index < listeners.length; index++) {
listeners[index].reject(error);
}
}
// There may be another session awaiting.
this._processQueue();
});
// Iterates over the queue and processes listeners.
const processListeners = () => {
const queue = this.queue[normalizedOptions];
if (!queue) {
return;
}
const originSet = session[kOriginSet];
for (let index = 0; index < originSet.length; index++) {
const origin = originSet[index];
if (origin in queue) {
const {listeners, completed} = queue[origin];
let index = 0;
// Prevents session overloading.
while (index < listeners.length && isFree()) {
// We assume `resolve(...)` calls `request(...)` *directly*,
// otherwise the session will get overloaded.
listeners[index].resolve(session);
index++;
}
queue[origin].listeners.splice(0, index);
if (queue[origin].listeners.length === 0 && !completed) {
delete queue[origin];
if (--queue[kLength] === 0) {
delete this.queue[normalizedOptions];
break;
}
}
// We're no longer free, no point in continuing.
if (!isFree()) {
break;
}
}
}
};
// The Origin Set cannot shrink. No need to check if it suddenly became covered by another one.
session.on('origin', () => {
session[kOriginSet] = getOriginSet() || [];
session[kGracefullyClosing] = false;
closeSessionIfCovered(this.sessions[normalizedOptions], session);
if (session[kGracefullyClosing] || !isFree()) {
return;
}
processListeners();
if (!isFree()) {
return;
}
// Close covered sessions (if possible).
closeCoveredSessions(this.sessions[normalizedOptions], session);
});
session.once('remoteSettings', () => {
// The Agent could have been destroyed already.
if (entry.destroyed) {
const error = new Error('Agent has been destroyed');
for (let index = 0; index < listeners.length; index++) {
listeners[index].reject(error);
}
session.destroy();
return;
}
// See https://github.com/nodejs/node/issues/38426
if (session.setLocalWindowSize) {
session.setLocalWindowSize(1024 * 1024 * 4); // 4 MB
}
session[kOriginSet] = getOriginSet() || [];
if (session.socket.encrypted) {
const mainOrigin = session[kOriginSet][0];
if (mainOrigin !== normalizedOrigin) {
const error = new Error(`Requested origin ${normalizedOrigin} does not match server ${mainOrigin}`);
for (let index = 0; index < listeners.length; index++) {
listeners[index].reject(error);
}
session.destroy();
return;
}
}
removeFromQueue();
{
const where = this.sessions;
if (normalizedOptions in where) {
const sessions = where[normalizedOptions];
sessions.splice(getSortedIndex(sessions, session, compareSessions), 0, session);
} else {
where[normalizedOptions] = [session];
}
}
receivedSettings = true;
this._emptySessionCount++;
this.emit('session', session);
this._accept(session, listeners, normalizedOrigin, options);
if (session[kCurrentStreamCount] === 0 && this._emptySessionCount > this.maxEmptySessions) {
this.closeEmptySessions(this._emptySessionCount - this.maxEmptySessions);
}
// `session.remoteSettings.maxConcurrentStreams` might get increased
session.on('remoteSettings', () => {
if (!isFree()) {
return;
}
processListeners();
if (!isFree()) {
return;
}
// In case the Origin Set changes
closeCoveredSessions(this.sessions[normalizedOptions], session);
});
});
// Shim `session.request()` in order to catch all streams
session[kRequest] = session.request;
session.request = (headers, streamOptions) => {
if (session[kGracefullyClosing]) {
throw new Error('The session is gracefully closing. No new streams are allowed.');
}
const stream = session[kRequest](headers, streamOptions);
// The process won't exit until the session is closed or all requests are gone.
session.ref();
if (session[kCurrentStreamCount]++ === 0) {
this._emptySessionCount--;
}
stream.once('close', () => {
if (--session[kCurrentStreamCount] === 0) {
this._emptySessionCount++;
session.unref();
if (this._emptySessionCount > this.maxEmptySessions || session[kGracefullyClosing]) {
session.close();
return;
}
}
if (session.destroyed || session.closed) {
return;
}
if (isFree() && !closeSessionIfCovered(this.sessions[normalizedOptions], session)) {
closeCoveredSessions(this.sessions[normalizedOptions], session);
processListeners();
if (session[kCurrentStreamCount] === 0) {
this._processQueue();
}
}
});
return stream;
};
} catch (error) {
removeFromQueue();
this._sessionCount--;
for (let index = 0; index < listeners.length; index++) {
listeners[index].reject(error);
}
}
};
entry.listeners = listeners;
entry.completed = false;
entry.destroyed = false;
this.queue[normalizedOptions][normalizedOrigin] = entry;
this.queue[normalizedOptions][kLength]++;
this._processQueue();
});
}
request(origin, options, headers, streamOptions) {
return new Promise((resolve, reject) => {
this.getSession(origin, options, [{
reject,
resolve: session => {
try {
const stream = session.request(headers, streamOptions);
// Do not throw before `request(...)` has been awaited
delayAsyncDestroy(stream);
resolve(stream);
} catch (error) {
reject(error);
}
}
}]);
});
}
async createConnection(origin, options) {
return Agent.connect(origin, options);
}
static connect(origin, options) {
options.ALPNProtocols = ['h2'];
const port = origin.port || 443;
const host = origin.hostname;
if (typeof options.servername === 'undefined') {
options.servername = host;
}
const socket = tls.connect(port, host, options);
if (options.socket) {
socket._peername = {
family: undefined,
address: undefined,
port
};
}
return socket;
}
closeEmptySessions(maxCount = Number.POSITIVE_INFINITY) {
let closedCount = 0;
const {sessions} = this;
// eslint-disable-next-line guard-for-in
for (const key in sessions) {
const thisSessions = sessions[key];
for (let index = 0; index < thisSessions.length; index++) {
const session = thisSessions[index];
if (session[kCurrentStreamCount] === 0) {
closedCount++;
session.close();
if (closedCount >= maxCount) {
return closedCount;
}
}
}
}
return closedCount;
}
destroy(reason) {
const {sessions, queue} = this;
// eslint-disable-next-line guard-for-in
for (const key in sessions) {
const thisSessions = sessions[key];
for (let index = 0; index < thisSessions.length; index++) {
thisSessions[index].destroy(reason);
}
}
// eslint-disable-next-line guard-for-in
for (const normalizedOptions in queue) {
const entries = queue[normalizedOptions];
// eslint-disable-next-line guard-for-in
for (const normalizedOrigin in entries) {
entries[normalizedOrigin].destroyed = true;
}
}
// New requests should NOT attach to destroyed sessions
this.queue = {};
this.tlsSessionCache.clear();
}
get emptySessionCount() {
return this._emptySessionCount;
}
get pendingSessionCount() {
return this._sessionCount - this._emptySessionCount;
}
get sessionCount() {
return this._sessionCount;
}
}
Agent.kCurrentStreamCount = kCurrentStreamCount;
Agent.kGracefullyClosing = kGracefullyClosing;
module.exports = {
Agent,
globalAgent: new Agent()
};
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