stateful HTTP client (Node)

.gitignore

/node_modules

http.js

"use strict";

let { Cookie, CookieJar } = require("tough-cookie");
let { promisify } = require("util");

exports.HTTPClient = class HTTPClient {
	constructor() {
		this.jar = new CookieJar();
	}

	async request(method, uri, headers, body, _trail = []) {
		if(!headers) {
			headers = {};
		}

		let { jar } = this;
		let getCookies = await promisify(jar.getCookies.bind(jar)); // XXX: inefficient
		let cookies = await getCookies(uri);
		if(cookies.length) {
			// XXX: overwrites caller's existing cookie header, if any
			headers.cookie = cookies.map(c => c.cookieString()).join("; ");
		}

		_trail.length || console.log("\n----"); // XXX: DEBUG
		console.log("\n>", method, uri); // XXX: DEBUG
		console.log("> Cookie:", headers.cookie || "--"); // XXX: DEBUG
		let res = await _request(method, uri, headers, body);
		console.log("\n<", res.status); // XXX: DEBUG

		cookies = res.headers["set-cookie"];
		if(cookies) {
			cookies.forEach(cookie => void console.log("< Set-Cookie:", cookie)); // XXX: DEBUG
			cookies = cookies.pop ?
				cookies.map(Cookie.parse) :
				[Cookie.parse(cookies)]; // TODO: error handling
			cookies.forEach(cookie => {
				jar.setCookie(cookie, uri); // TODO: error handling
			});
		}

		// follow redirects
		let { status } = res;
		let { location } = res.headers;
		if(location && status >= 300 && status < 400) {
			console.log("< Location:", location); // XXX: DEBUG
			if(!location.includes("://")) { // not fully qualified
				let _uri = new URL(uri);
				location = _uri.origin + location;
				console.log("< Location:", location); // XXX: DEBUG
			}
			// XXX: simplistic because `GET` might not be correct for 307, 308 and perhaps 302
			[res, _trail] = await this.request("GET", location, null, null,
					_trail.concat(res));
		}

		return [res, _trail];
	}
};

function _request(method, uri, headers, body) {
	let proto = determineProtocol(uri);
	return new Promise((resolve, reject) => {
		let onResponse = res => {
			let chunks = [];
			res.on("data", chunk => {
				chunks.push(chunk);
			});
			res.on("end", () => {
				let body =  chunks.length && chunks.
					// XXX: assumes UTF-8 string
					map(buffer => buffer.toString("utf8")).join("");
				chunks = null;
				resolve(new HTTPResponse(uri, res.statusCode, res.headers, body));
			});
			res.on("error", err => {
				reject(err);
			});
		};

		let req = proto.request(uri, { method }, onResponse);
		req.on("error", err => void reject(err));
		if(body) {
			console.log("----", body); // XXX: DEBUG
			req.write(body);
		}
		req.end();
	});
}

class HTTPResponse {
	constructor(uri, status, headers, body) {
		this.uri = uri;
		this.status = status;
		this.headers = headers;
		this.body = body || null;
	}
}

function determineProtocol(uri) {
	if(uri.startsWith("https://")) {
		return require("https");
	}
	if(uri.startsWith("http://")) {
		return require("http");
	}
	throw new Error(`unrecognized URI: ${uri}`);
}

package.json

{
  "dependencies": {
    "tough-cookie": "^4.0.0"
  }
}

sample.js

#!/usr/bin/env node

"use strict";

let { HTTPClient } = require("./http");
let qs = require("querystring");

let ENTRY_POINT = "http://example.org";
let LOGIN_FORM = "https://example.org/login";
let RESOURCE = "https://example.org/dashboard";
let USERNAME = "foo";
let PASSWORD = "bar";

main();

async function main() {
	let client = new HTTPClient();

	await client.request("GET", ENTRY_POINT);

	await client.request("POST", LOGIN_FORM, {
		Acept: "text/html",
		"Content-Type": "application/x-www-form-urlencoded"
	}, qs.stringify({
		username: USERNAME,
		password: PASSWORD
	}));

	let [res, trail] = await client.request("GET", RESOURCE, {
		Accept: "application/json"
	});
	console.log("~~", res.status, res.body);
	console.log("--", trail);
}