65 lines
2.4 KiB
TypeScript
65 lines
2.4 KiB
TypeScript
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import Axios from "axios";
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import ipaddr from 'ipaddr.js';
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import { Resolver } from 'dns';
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import { promisify } from 'util';
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import {LocalUrlError} from "./LocalUrlError";
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import {ITiledMap} from "@workadventure/tiled-map-type-guard";
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import {isTiledMap} from "@workadventure/tiled-map-type-guard/dist";
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class MapFetcher {
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async fetchMap(mapUrl: string): Promise<ITiledMap> {
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// Before trying to make the query, let's verify the map is actually on the open internet (and not a local test map)
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if (await this.isLocalUrl(mapUrl)) {
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throw new LocalUrlError('URL for map "'+mapUrl+'" targets a local map');
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}
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// Note: mapUrl is provided by the client. A possible attack vector would be to use a rogue DNS server that
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// returns local URLs. Alas, Axios cannot pin a URL to a given IP. So "isLocalUrl" and Axios.get could potentially
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// target to different servers (and one could trick Axios.get into loading resources on the internal network
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// despite isLocalUrl checking that.
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// We can deem this problem not that important because:
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// - We make sure we are only passing "GET" requests
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// - The result of the query is never displayed to the end user
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const res = await Axios.get(mapUrl, {
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maxContentLength: 50*1024*1024, // Max content length: 50MB. Maps should not be bigger
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});
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if (!isTiledMap(res.data)) {
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throw new Error('Invalid map format for map '+mapUrl);
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}
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return res.data;
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}
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/**
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* Returns true if the domain name is localhost of *.localhost
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* Returns true if the domain name resolves to an IP address that is "private" (like 10.x.x.x or 192.168.x.x)
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*/
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private async isLocalUrl(url: string): Promise<boolean> {
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const urlObj = new URL(url);
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if (urlObj.hostname === 'localhost' || urlObj.hostname.endsWith('.localhost')) {
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return true;
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}
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let addresses = [];
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if (!ipaddr.isValid(urlObj.hostname)) {
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const resolver = new Resolver();
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addresses = await promisify(resolver.resolve)(urlObj.hostname);
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} else {
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addresses = [urlObj.hostname];
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}
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for (const address of addresses) {
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const addr = ipaddr.parse(address);
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if (addr.range() !== 'unicast') {
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return true;
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}
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}
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return false;
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}
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}
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export const mapFetcher = new MapFetcher();
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