fetch-dns/Rrtypes.ts

A drop-in replacement of Node's 'dns' module using 'fetch' and DNS-over-HTTPS

/** @format */

import data from "./RrtypesData.json";
import _ from "lodash";
import Debug from "debug";

const log = Debug("fetch-dns:rrtypes");
const debug = log.extend("debug");
if (debug.enabled) log.enabled = true;

const rrtypeMap = _.fromPairs(
	_.flatMap(data, (rrtype) => {
		debug("Processing RRTYPE map entry", rrtype);
		const { TYPE, Value } = rrtype || {};
		if (
			TYPE === "Unassigned" ||
			TYPE === "Private use" ||
			TYPE === "Reserved"
		) {
			debug("Skipping unused RRTYPE allocation", TYPE, Value);
			return [];
		}
		const [start, stop] = _.map(_.split(Value, "-", 2), _.toFinite);
		if (_.includes(Value, "-")) {
			if (start === 0 || stop === 0) {
				log("Discovered an unbounded value", rrtype);
				return [];
			} else {
				return _.map(_.range(start, stop + 1), (i) => [_.toString(i), TYPE]);
			}
		} else {
			return [[Value, TYPE]];
		}
	}),
);

log(rrtypeMap);

export default function lookupRrtype(rrtype: number): string | false {
	/* eslint-disable @typescript-eslint/no-unsafe-assignment */
	const result = _.get(rrtypeMap, _.toString(rrtype), null);
	debug("Lookup up RRTYPE", { rrtype, result });
	/* eslint-enable @typescript-eslint/no-unsafe-assignment */
	if (_.isNil(result) || result === false) return false;
	if (_.isString(result)) {
		return result;
	} else {
		throw new Error(
			`INTERNAL ERROR: rrtype return was neither nil nor a string, but '${typeof result}'`,
		);
	}
}