@fontoxml/fontoxml-development-tools/src/configureNetworkAgent.js

Development tools for Fonto.

import {
	Dispatcher,
	getGlobalDispatcher,
	ProxyAgent,
	setGlobalDispatcher,
} from 'undici';

// These are more of a convention than a standard. Most implementations seem to
// prioritise the lowercase variant over the uppercase one.
// See: https://about.gitlab.com/blog/2021/01/27/we-need-to-talk-no-proxy/
const HTTP_PROXY = process.env['http_proxy'] || process.env['HTTP_PROXY'];
const HTTPS_PROXY = process.env['https_proxy'] || process.env['HTTPS_PROXY'];
const NO_PROXY = process.env['no_proxy'] || process.env['NO_PROXY'];

const defaultDispatcher = getGlobalDispatcher();

class ProxyDispatcher extends Dispatcher {
	constructor(proxyAgents, noProxyRules) {
		super();
		this.proxyAgents = proxyAgents;
		this.noProxyRules = noProxyRules;
	}

	dispatch(options, handler) {
		if (options.origin) {
			const { hostname, protocol, port } = new URL(options.origin);
			const proxyAgent =
				this.proxyAgents[protocol] || this.proxyAgents['http:'];
			const skipProxy = this.noProxyRules.some((rule) => {
				if (!rule.port && rule.host === '*') {
					return true;
				}

				// Match rule '(.)example.com' with 'example.com' and 'www.example.com', but not
				// with 'other-example.com'.
				if (
					hostname === rule.host ||
					hostname.endsWith(`.${rule.host}`)
				) {
					return rule.port === undefined
						? true
						: (port || (protocol === 'https:' ? '443' : '80')) ===
								rule.port;
				}

				return false;
			});

			if (proxyAgent && !skipProxy) {
				return proxyAgent.dispatch(options, handler);
			}
		}
		return defaultDispatcher.dispatch(options, handler);
	}
}

export default function configureNetworkAgent(app) {
	function getProxyAgent(config) {
		try {
			return config ? new ProxyAgent(config) : undefined;
		} catch (error) {
			app.error(
				undefined,
				new app.logger.ErrorWithInnerError(
					`Could not parse proxy configuration "${config}".`,
					error
				)
			);
			return process.exit(1);
		}
	}

	const proxyAgents = {
		'http:': getProxyAgent(HTTP_PROXY),
		'https:': getProxyAgent(HTTPS_PROXY),
	};

	const noProxyRules = NO_PROXY
		? NO_PROXY.split(',').map((rule) => {
				const [host, port] = rule.trim().split(':');
				return {
					host: host.startsWith('.') ? host.substring(1) : host,
					port,
				};
		  })
		: [];

	setGlobalDispatcher(new ProxyDispatcher(proxyAgents, noProxyRules));
}