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server.ts
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/**
* Request handling.
*
* @author mia-pi-git, Zarel
*/
import * as http from 'http';
import * as https from 'https';
import * as child from 'child_process';
import * as dns from 'dns';
import * as fs from 'fs';
import {toID, md5} from './utils';
import {Config} from './config-loader';
import {actions} from './actions';
import {User, Session} from './user';
import {URLSearchParams} from 'url';
import IPTools from './ip-tools';
/**
* API request output should not be valid JavaScript.
* This is to protect against a CSRF-like attack. Imagine you have an API:
* https://example.com/getmysecrets.json
* Which returns:
* {"yoursecrets": [1, 2, 3]}
*
* An attacker could trick a user into visiting a site overriding the
* Array or Object constructor, and then containing:
* <script src="https://example.com/getmysecrets.json"></script>
*
* This could let them steal the secrets. In modern times, browsers
* are protected against this kind of attack, but our `]` adds some
* safety for older browsers.
*
* Adding `]` to the beginning makes sure that the output is a syntax
* error in JS, so treating it as a JS file will simply crash and fail.
*/
const DISPATCH_PREFIX = ']';
/**
* Throw this to end a request with an `actionerror` message.
*/
export class ActionError extends Error {
httpStatus: number;
constructor(message: string, httpStatus = 200) {
super(message);
this.httpStatus = httpStatus;
this.name = 'ActionError';
Error.captureStackTrace(this, ActionError);
}
}
export interface ActionRequest {
/** Name of the action */
act: string;
/** SID to make a request as a logged-in user (usually passed in cookies but can be passed here too) */
sid?: string;
servertoken?: string;
serverid?: string;
[k: string]: string | undefined;
}
export interface RegisteredServer {
name: string;
id: string;
server: string;
port: number;
token?: string;
skipipcheck?: boolean;
ipcache?: string;
}
export type QueryHandler = (
this: ActionContext, params: ActionRequest
) => {[k: string]: any} | string | Promise<{[k: string]: any} | string>;
export class ActionContext {
readonly request: http.IncomingMessage;
readonly response: http.ServerResponse;
readonly session: Session;
readonly ActionError = ActionError;
user: User;
private prefix: string | null = null;
readonly body: ActionRequest;
useDispatchPrefix = true;
constructor(req: http.IncomingMessage, res: http.ServerResponse, body: ActionRequest) {
this.request = req;
this.response = res;
this.session = new Session(this);
this.user = null!;
this.body = body;
}
async executeActions() {
const body = this.body;
const act = body.act;
if (!act) throw new ActionError('Request needs an action - /api/[act] or JSON {act: [act]}', 404);
const handler = actions[act];
if (!handler) throw new ActionError(`Request type "${act}" was not recognized.`, 404);
// the cookies are actually the only CSRF risk,
// so there's no problem setting CORS
// if they send it directly
if (ActionContext.parseURLRequest(this.request).sid?.length) {
this.setHeader('Access-Control-Allow-Origin', '*');
}
try {
this.user = await this.session.getUser();
const result = await handler.call(this, body);
if (result === null) return {code: 404};
return result;
} catch (e: any) {
if (e instanceof ActionError) {
return {actionerror: e.message};
}
for (const k of ['pass', 'password']) delete body[k];
Server.crashlog(e, 'an API request', body);
if (Config.devmode && Config.devmode === body.devmode) {
throw new ActionError(e.stack + '\n' + JSON.stringify(body), 200);
} else {
throw new ActionError("Internal Server Error", 500);
}
}
}
static async getRequestBody(req: http.IncomingMessage) {
let body = '';
for await (const data of req) body += data;
return body;
}
static sanitizeBody(body: any): ActionRequest {
if (typeof body === 'string') return {act: body};
if (typeof body !== 'object') throw new ActionError("Body must be an object or string", 400);
if (!('act' in body)) body.act = ''; // we'll let the action handler throw the error
for (const k in body) {
body[k] = '' + body[k];
}
return body as ActionRequest;
}
static async getBody(req: http.IncomingMessage): Promise<ActionRequest | ActionRequest[]> {
let result: {[k: string]: any} = this.parseURLRequest(req);
let json;
const bodyData = await this.getRequestBody(req);
if (bodyData) {
try {
if (bodyData.startsWith('[') || bodyData.startsWith('{')) {
json = bodyData;
} else {
Object.assign(result, Object.fromEntries(new URLSearchParams(bodyData)));
}
} catch {}
}
if (result.act === 'json' || !result.act) {
json = result.json;
result.act = '';
delete result.json;
}
try {
const jsonResult = JSON.parse(json);
if (Array.isArray(jsonResult)) {
return jsonResult.map(body => this.sanitizeBody({...result, ...body}));
} else {
result = Object.assign(result, jsonResult);
}
} catch {}
return this.sanitizeBody(result);
}
static parseURLRequest(req: http.IncomingMessage) {
if (!req.url) return {};
const [pathname, params] = req.url.split('?');
const act = pathname.split('/api/').slice(1).join('/api/');
const result = params ? Object.fromEntries(new URLSearchParams(params)) : {};
if (act) result.act = act;
return result;
}
allowCORS(origin?: string) {
if (!origin) origin = this.request.headers.origin || '*';
this.setHeader('Access-Control-Allow-Origin', origin);
this.setHeader('Access-Control-Allow-Credentials', 'true');
}
verifyCrossDomainRequest(): string {
if (typeof this.prefix === 'string') return this.prefix;
// No cross-domain multi-requests for security reasons.
// No need to do anything if this isn't a cross-domain request.
const origin = this.request.headers.origin;
if (!origin) {
return '';
}
let prefix = null;
for (const [regex, host] of Config.cors) {
if (!regex.test(origin)) continue;
prefix = host;
}
if (prefix === null) {
// Bogus request.
return '';
}
// Valid CORS request.
this.allowCORS(origin);
this.prefix = prefix;
return prefix;
}
setPrefix(prefix: string) {
this.prefix = prefix;
}
isTrustedProxy(ip: string) {
// account for shit like ::ffff:127.0.0.1
return ip === '::ffff:127.0.0.1' || Config.trustedproxies.some(f => IPTools.checkPattern(f, ip));
}
_ip = '';
getIp() {
if (this._ip) return this._ip;
let ip = this.request.socket.remoteAddress || "";
if (this.isTrustedProxy(ip)) {
const ips = ((this.request.headers['x-forwarded-for'] || '') + "").split(',').reverse();
for (let proxy of ips) {
proxy = proxy.trim();
if (!this.isTrustedProxy(proxy)) {
ip = proxy;
break;
}
}
}
this._ip = ip;
return ip;
}
setHeader(name: string, value: string | string[]) {
this.response.setHeader(name, value);
}
getServer(requireToken?: boolean) {
return SimServers.getServer(this, requireToken);
}
async requireServer() {
const server = await this.getServer(true);
if (!server) {
throw new ActionError(
`This API can only be used by a registered server. Your IP (${this.getIp()}) is unrecognized. ` +
`If your server is registered, you may need to set up token authentication.`
);
}
return server;
}
async requireMainServer(mainServerId = Config.mainserver) {
const server = await this.requireServer();
if (!mainServerId) throw new ActionError(`Main server misconfigured`, 500);
if (server.id !== mainServerId) throw new ActionError(`This API can only be used by the main server.`);
return server;
}
}
export const SimServers = new class SimServersT {
servers: {[k: string]: RegisteredServer} = this.loadServers();
hostCache = new Map<string, string>();
constructor() {
fs.watchFile(Config.serverlist, (curr, prev) => {
if (curr.mtime > prev.mtime) {
this.loadServers();
}
});
}
async getHost(server: string) {
let result = this.hostCache.get(server);
if (result) return result;
const address = await new Promise<string>(resolve => {
dns.resolve(server, (err, addresses) => {
if (err) {
// i don't like this. BUT we have to match behavior with
// php's gethostbyname, which returns the host given if no results
resolve(server);
} else { // see above
resolve(addresses[0] || server);
}
});
});
result = address;
this.hostCache.set(server, result);
return result;
}
async getServer(context: ActionContext, requireToken = false): Promise<RegisteredServer | null> {
const serverid = toID(context.body.serverid);
const server = this.servers[serverid];
if (!server) return null;
const ip = context.getIp();
if (!server.skipipcheck && !server.token && serverid !== Config.mainserver) {
if (!server.ipcache) {
server.ipcache = await this.getHost(server.server);
}
if (ip !== server.ipcache) return null;
}
if (server.token && requireToken) {
if (server.token !== md5(context.body.servertoken || '')) {
throw new ActionError(`Invalid servertoken sent for requested serverid.`);
}
}
return server;
}
loadServers(path = Config.serverlist): {[k: string]: RegisteredServer} {
if (!path) return {};
try {
const stdout = child.execFileSync(
`php`, ['-f', __dirname + '/../../src/lib/load-servers.php', path]
).toString();
return JSON.parse(stdout);
} catch (e: any) {
if (!['ENOENT', 'ENOTDIR', 'ENAMETOOLONG'].includes(e.code)) throw e;
}
return {};
}
};
export class Server {
server: http.Server;
httpsServer: https.Server | null;
port: number;
awaitingEnd?: () => void;
closing?: Promise<void>;
activeRequests = 0;
constructor(port = (Config.port || 8000)) {
this.port = port;
this.server = http.createServer((req, res) => void this.handle(req, res));
this.server.listen(port);
this.httpsServer = null;
if (Config.ssl) {
this.httpsServer = https.createServer(Config.ssl, (req, res) => void this.handle(req, res));
this.httpsServer.listen(Config.ssl.port || 8043);
}
}
static crashlog(error: unknown, source = '', details = {}) {
if (!Config.pspath) {
return console.log(`${source} crashed`, error, details);
}
try {
const {crashlogger} = require(Config.pspath);
crashlogger(error, source, {...details, date: new Date().toISOString()}, Config.crashguardemail);
} catch (e) {
// don't have data/pokemon-showdown built? something else went wrong? oh well
console.log('CRASH', error);
console.log('SUBCRASH', e);
}
}
async handle(req: http.IncomingMessage, res: http.ServerResponse) {
this.activeRequests++;
res.setHeader('Content-Type', 'text/plain; charset=utf-8');
let useDispatchPrefix = true;
try {
const body = await ActionContext.getBody(req);
let result;
if (Array.isArray(body)) {
let context = new ActionContext(req, res, body[0]);
if (body.length > 20) {
if (!await context.getServer(true)) {
throw new ActionError(`Only registered servers can send >20 requests at once.`, 403);
}
}
result = [];
for (const curBody of body) {
if (context.body !== curBody) context = new ActionContext(req, res, curBody);
result.push(await context.executeActions());
}
if (!context.useDispatchPrefix) useDispatchPrefix = false;
} else {
const context = new ActionContext(req, res, body);
// turn undefined into null so it can be JSON stringified
result = await context.executeActions() ?? null;
if (!context.useDispatchPrefix) useDispatchPrefix = false;
}
this.ensureHeaders(res);
res.writeHead(200).end(this.stringify(result, useDispatchPrefix));
} catch (e: any) {
this.ensureHeaders(res);
if (e instanceof ActionError) {
if (e.httpStatus) {
res.writeHead(e.httpStatus).end('Error: ' + e.message);
} else {
res.writeHead(200).end(this.stringify({actionerror: e.message}));
}
} else {
Server.crashlog(e);
res.writeHead(500).end("Internal Server Error");
}
}
this.activeRequests--;
if (!this.activeRequests) this.awaitingEnd?.();
}
ensureHeaders(res: http.ServerResponse) {
if (this.awaitingEnd) res.setHeader('Connection', 'close');
}
close() {
if (this.closing) return this.closing;
this.server.close();
if (!this.activeRequests) return Promise.resolve();
this.closing = new Promise<void>(resolve => {
this.awaitingEnd = resolve;
});
return this.closing;
}
stringify(response: any, useDispatchPrefix = true) {
if (typeof response === 'string') {
return response; // allow ending with just strings;
}
// see DISPATCH_PREFIX
return (
(useDispatchPrefix ? DISPATCH_PREFIX : "") + JSON.stringify(response)
);
}
}