cloudflare--workers-sdk/packages/workers-shared/utils/configuration/validateURL.ts

export const extractPathname = (
	path = "/",
	includeSearch: boolean,
	includeHash: boolean
): string => {
	if (!path.startsWith("/")) {
		path = `/${path}`;
	}
	const url = new URL(`//${path}`, "relative://");
	return `${url.pathname}${includeSearch ? url.search : ""}${
		includeHash ? url.hash : ""
	}`;
};

const URL_REGEX = /^https:\/\/+(?<host>[^/]+)\/?(?<path>.*)/;
const HOST_WITH_PORT_REGEX = /.*:\d+$/;
const PATH_REGEX = /^\//;

export const validateUrl = (
	token: string,
	onlyRelative = false,
	disallowPorts = false,
	includeSearch = false,
	includeHash = false
): [undefined, string] | [string, undefined] => {
	const host = URL_REGEX.exec(token);
	if (host && host.groups && host.groups.host) {
		if (onlyRelative) {
			return [
				undefined,
				`Only relative URLs are allowed. Skipping absolute URL ${token}.`,
			];
		}

		if (disallowPorts && host.groups.host.match(HOST_WITH_PORT_REGEX)) {
			return [
				undefined,
				`Specifying ports is not supported. Skipping absolute URL ${token}.`,
			];
		}

		return [
			`https://${host.groups.host}${extractPathname(
				host.groups.path,
				includeSearch,
				includeHash
			)}`,
			undefined,
		];
	} else {
		if (!token.startsWith("/") && onlyRelative) {
			token = `/${token}`;
		}

		const path = PATH_REGEX.exec(token);
		if (path) {
			try {
				return [extractPathname(token, includeSearch, includeHash), undefined];
			} catch {
				return [undefined, `Error parsing URL segment ${token}. Skipping.`];
			}
		}
	}

	return [
		undefined,
		onlyRelative
			? "URLs should begin with a forward-slash."
			: 'URLs should either be relative (e.g. begin with a forward-slash), or use HTTPS (e.g. begin with "https://").',
	];
};

export function urlHasHost(token: string): boolean {
	const host = URL_REGEX.exec(token);
	return Boolean(host && host.groups && host.groups.host);
}