/
index.ts
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/
index.ts
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import * as net from 'net';
import * as tls from 'tls';
import * as http from 'http';
import createDebug from 'debug';
import { once } from 'events';
import { Agent, AgentConnectOpts } from 'agent-base';
import { URL } from 'node:url';
import type { OutgoingHttpHeaders } from 'http';
const debug = createDebug('http-proxy-agent');
// eslint-disable-next-line @typescript-eslint/no-unused-vars
type Protocol<T> = T extends `${infer Protocol}:${infer _}` ? Protocol : never;
type ConnectOptsMap = {
http: Omit<net.TcpNetConnectOpts, 'host' | 'port'>;
https: Omit<tls.ConnectionOptions, 'host' | 'port'>;
};
type ConnectOpts<T> = {
[P in keyof ConnectOptsMap]: Protocol<T> extends P
? ConnectOptsMap[P]
: never;
}[keyof ConnectOptsMap];
export type HttpProxyAgentOptions<T> = ConnectOpts<T> &
http.AgentOptions & {
headers?: OutgoingHttpHeaders | (() => OutgoingHttpHeaders);
};
interface HttpProxyAgentClientRequest extends http.ClientRequest {
outputData?: {
data: string;
}[];
_header?: string | null;
_implicitHeader(): void;
}
/**
* The `HttpProxyAgent` implements an HTTP Agent subclass that connects
* to the specified "HTTP proxy server" in order to proxy HTTP requests.
*/
export class HttpProxyAgent<Uri extends string> extends Agent {
static protocols = ['http', 'https'] as const;
readonly proxy: URL;
proxyHeaders: OutgoingHttpHeaders | (() => OutgoingHttpHeaders);
connectOpts: net.TcpNetConnectOpts & tls.ConnectionOptions;
constructor(proxy: Uri | URL, opts?: HttpProxyAgentOptions<Uri>) {
super(opts);
this.proxy = typeof proxy === 'string' ? new URL(proxy) : proxy;
this.proxyHeaders = opts?.headers ?? {};
debug('Creating new HttpProxyAgent instance: %o', this.proxy.href);
// Trim off the brackets from IPv6 addresses
const host = (this.proxy.hostname || this.proxy.host).replace(
/^\[|\]$/g,
''
);
const port = this.proxy.port
? parseInt(this.proxy.port, 10)
: this.proxy.protocol === 'https:'
? 443
: 80;
this.connectOpts = {
...(opts ? omit(opts, 'headers') : null),
host,
port,
};
}
addRequest(req: HttpProxyAgentClientRequest, opts: AgentConnectOpts): void {
req._header = null;
this.setRequestProps(req, opts);
// @ts-expect-error `addRequest()` isn't defined in `@types/node`
super.addRequest(req, opts);
}
setRequestProps(
req: HttpProxyAgentClientRequest,
opts: AgentConnectOpts
): void {
const { proxy } = this;
const protocol = opts.secureEndpoint ? 'https:' : 'http:';
const hostname = req.getHeader('host') || 'localhost';
const base = `${protocol}//${hostname}`;
const url = new URL(req.path, base);
if (opts.port !== 80) {
url.port = String(opts.port);
}
// Change the `http.ClientRequest` instance's "path" field
// to the absolute path of the URL that will be requested.
req.path = String(url);
// Inject the `Proxy-Authorization` header if necessary.
const headers: OutgoingHttpHeaders =
typeof this.proxyHeaders === 'function'
? this.proxyHeaders()
: { ...this.proxyHeaders };
if (proxy.username || proxy.password) {
const auth = `${decodeURIComponent(
proxy.username
)}:${decodeURIComponent(proxy.password)}`;
headers['Proxy-Authorization'] = `Basic ${Buffer.from(
auth
).toString('base64')}`;
}
if (!headers['Proxy-Connection']) {
headers['Proxy-Connection'] = this.keepAlive
? 'Keep-Alive'
: 'close';
}
for (const name of Object.keys(headers)) {
const value = headers[name];
if (value) {
req.setHeader(name, value);
}
}
}
async connect(
req: HttpProxyAgentClientRequest,
opts: AgentConnectOpts
): Promise<net.Socket> {
req._header = null;
if (!req.path.includes('://')) {
this.setRequestProps(req, opts);
}
// At this point, the http ClientRequest's internal `_header` field
// might have already been set. If this is the case then we'll need
// to re-generate the string since we just changed the `req.path`.
let first: string;
let endOfHeaders: number;
debug('Regenerating stored HTTP header string for request');
req._implicitHeader();
if (req.outputData && req.outputData.length > 0) {
debug(
'Patching connection write() output buffer with updated header'
);
first = req.outputData[0].data;
endOfHeaders = first.indexOf('\r\n\r\n') + 4;
req.outputData[0].data =
req._header + first.substring(endOfHeaders);
debug('Output buffer: %o', req.outputData[0].data);
}
// Create a socket connection to the proxy server.
let socket: net.Socket;
if (this.proxy.protocol === 'https:') {
debug('Creating `tls.Socket`: %o', this.connectOpts);
socket = tls.connect(this.connectOpts);
} else {
debug('Creating `net.Socket`: %o', this.connectOpts);
socket = net.connect(this.connectOpts);
}
// Wait for the socket's `connect` event, so that this `callback()`
// function throws instead of the `http` request machinery. This is
// important for i.e. `PacProxyAgent` which determines a failed proxy
// connection via the `callback()` function throwing.
await once(socket, 'connect');
return socket;
}
}
function omit<T extends object, K extends [...(keyof T)[]]>(
obj: T,
...keys: K
): {
[K2 in Exclude<keyof T, K[number]>]: T[K2];
} {
const ret = {} as {
[K in keyof typeof obj]: (typeof obj)[K];
};
let key: keyof typeof obj;
for (key in obj) {
if (!keys.includes(key)) {
ret[key] = obj[key];
}
}
return ret;
}