134 lines
3.3 KiB
TypeScript
134 lines
3.3 KiB
TypeScript
// Copyright 2023 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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import { ProxyAgent } from 'proxy-agent';
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import net from 'net';
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import { URL } from 'url';
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import type { LookupOneOptions, LookupAddress } from 'dns';
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import { lookup } from 'dns/promises';
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import * as log from '../logging/log';
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import { happyEyeballs } from './createHTTPSAgent';
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import type { ConnectOptionsType } from './createHTTPSAgent';
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import { explodePromise } from './explodePromise';
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import { SECOND } from './durations';
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import { drop } from './drop';
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// Warning threshold
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const CONNECT_THRESHOLD_MS = SECOND;
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const SOCKS_PROTOCOLS = new Set([
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'socks:',
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'socks4:',
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'socks4a:',
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'socks5:',
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'socks5h:',
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]);
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export function createProxyAgent(proxyUrl: string): ProxyAgent {
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const { port: portStr, hostname: proxyHost, protocol } = new URL(proxyUrl);
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let defaultPort: number | undefined;
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if (protocol === 'http:') {
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defaultPort = 80;
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} else if (protocol === 'https:') {
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defaultPort = 443;
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} else if (SOCKS_PROTOCOLS.has(protocol)) {
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defaultPort = 1080;
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}
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const port = portStr ? parseInt(portStr, 10) : defaultPort;
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async function happyLookup(
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host: string,
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opts: LookupOneOptions
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): Promise<LookupAddress> {
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if (opts.all) {
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throw new Error('createProxyAgent: all=true lookup is not supported');
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}
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const addresses = await lookup(host, { all: true });
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// SOCKS 4/5 resolve target host before sending it to the proxy.
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if (host !== proxyHost) {
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const idx = Math.floor(Math.random() * addresses.length);
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return addresses[idx];
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}
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const start = Date.now();
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const { socket, address, v4Attempts, v6Attempts } = await happyEyeballs({
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addresses,
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port,
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connect,
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});
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const duration = Date.now() - start;
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const logLine =
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`createProxyAgent.lookup(${host}): connected to ` +
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`IPv${address.family} addr after ${duration}ms ` +
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`(attempts v4=${v4Attempts} v6=${v6Attempts})`;
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if (v4Attempts + v6Attempts > 1 || duration > CONNECT_THRESHOLD_MS) {
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log.warn(logLine);
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} else {
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log.info(logLine);
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}
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// Sadly we can't return socket to proxy-agent
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socket.destroy();
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return address;
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}
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async function happyLookupWithCallback(
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host: string,
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opts: LookupOneOptions,
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callback: (
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err: NodeJS.ErrnoException | null,
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address: string,
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family: number
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) => void
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): Promise<void> {
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try {
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const { address, family } = await happyLookup(host, opts);
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callback(null, address, family);
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} catch (error) {
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callback(error, '', -1);
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}
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}
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return new ProxyAgent({
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lookup:
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port !== undefined
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? (...args) => drop(happyLookupWithCallback(...args))
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: undefined,
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getProxyForUrl() {
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return proxyUrl;
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},
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});
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}
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async function connect({
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port,
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address,
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abortSignal,
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}: ConnectOptionsType): Promise<net.Socket> {
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const socket = net.connect({
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port,
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host: address,
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signal: abortSignal,
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});
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const { promise: onConnect, resolve, reject } = explodePromise<void>();
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socket.once('connect', resolve);
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socket.once('error', reject);
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try {
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await onConnect;
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} finally {
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socket.removeListener('connect', resolve);
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socket.removeListener('error', reject);
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}
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return socket;
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}
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