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ms/packages/websocket/src/engine.io/server.ts
2023-02-09 13:49:48 +08:00

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import * as qs from "querystring";
import { parse } from "url";
// const base64id = require("base64id")
import transports from "./transports";
import { EventEmitter } from "events";
import { Socket } from "./socket";
// import debugModule from "debug"
// import { serialize } from "cookie"
// import { Server as DEFAULT_WS_ENGINE } from "ws"
import { WebSocketServer as DEFAULT_WS_ENGINE } from "../server";
// import { IncomingMessage, Server as HttpServer } from "http"
// import { CookieSerializeOptions } from "cookie"
// import { CorsOptions, CorsOptionsDelegate } from "cors"
const debug = require("../debug")("engine");
const kResponseHeaders = Symbol("responseHeaders");
import { Request } from "../server/request";
import { WebSocketClient } from "../server/client";
type Transport = "polling" | "websocket";
export interface AttachOptions {
/**
* name of the path to capture
* @default "/engine.io"
*/
path?: string;
/**
* destroy unhandled upgrade requests
* @default true
*/
destroyUpgrade?: boolean;
/**
* milliseconds after which unhandled requests are ended
* @default 1000
*/
destroyUpgradeTimeout?: number;
/**
* Whether we should add a trailing slash to the request path.
* @default true
*/
addTrailingSlash?: boolean;
}
export interface ServerOptions {
/**
* how many ms without a pong packet to consider the connection closed
* @default 20000
*/
pingTimeout?: number;
/**
* how many ms before sending a new ping packet
* @default 25000
*/
pingInterval?: number;
/**
* how many ms before an uncompleted transport upgrade is cancelled
* @default 10000
*/
upgradeTimeout?: number;
/**
* how many bytes or characters a message can be, before closing the session (to avoid DoS).
* @default 1e5 (100 KB)
*/
maxHttpBufferSize?: number;
/**
* A function that receives a given handshake or upgrade request as its first parameter,
* and can decide whether to continue or not. The second argument is a function that needs
* to be called with the decided information: fn(err, success), where success is a boolean
* value where false means that the request is rejected, and err is an error code.
*/
// allowRequest?: (
// req: IncomingMessage,
// fn: (err: string | null | undefined, success: boolean) => void
// ) => void
/**
* the low-level transports that are enabled
* @default ["polling", "websocket"]
*/
transports?: Transport[];
/**
* whether to allow transport upgrades
* @default true
*/
allowUpgrades?: boolean;
/**
* parameters of the WebSocket permessage-deflate extension (see ws module api docs). Set to false to disable.
* @default false
*/
perMessageDeflate?: boolean | object;
/**
* parameters of the http compression for the polling transports (see zlib api docs). Set to false to disable.
* @default true
*/
httpCompression?: boolean | object;
/**
* what WebSocket server implementation to use. Specified module must
* conform to the ws interface (see ws module api docs).
* An alternative c++ addon is also available by installing eiows module.
*
* @default `require("ws").Server`
*/
wsEngine?: any;
/**
* an optional packet which will be concatenated to the handshake packet emitted by Engine.IO.
*/
initialPacket?: any;
/**
* configuration of the cookie that contains the client sid to send as part of handshake response headers. This cookie
* might be used for sticky-session. Defaults to not sending any cookie.
* @default false
*/
cookie?: { /*CookieSerializeOptions & */ name: string } | boolean;
/**
* the options that will be forwarded to the cors module
*/
// cors?: CorsOptions | CorsOptionsDelegate
/**
* whether to enable compatibility with Socket.IO v2 clients
* @default false
*/
allowEIO3?: boolean;
}
/**
* An Express-compatible middleware.
*
* Middleware functions are functions that have access to the request object (req), the response object (res), and the
* next middleware function in the applications request-response cycle.
*
* @see https://expressjs.com/en/guide/using-middleware.html
*/
type Middleware = (
req: any /*IncomingMessage*/,
res: any /*ServerResponse*/,
next: () => void
) => void;
export abstract class BaseServer extends EventEmitter {
public opts: ServerOptions;
protected clients: any;
private clientsCount: number;
protected middlewares: Middleware[] = [];
/**
* Server constructor.
*
* @param {Object} opts - options
* @api public
*/
constructor(opts: ServerOptions = {}) {
super();
this.clients = {};
this.clientsCount = 0;
this.opts = Object.assign(
{
wsEngine: DEFAULT_WS_ENGINE,
pingTimeout: 20000,
pingInterval: 25000,
upgradeTimeout: 10000,
maxHttpBufferSize: 1e6,
transports: Object.keys(transports),
allowUpgrades: true,
httpCompression: {
threshold: 1024,
},
cors: false,
allowEIO3: false,
},
opts
);
// if (opts.cookie) {
// this.opts.cookie = Object.assign(
// {
// name: "io",
// path: "/",
// // @ts-ignore
// httpOnly: opts.cookie.path !== false,
// sameSite: "lax",
// },
// opts.cookie
// );
// }
// if (this.opts.cors) {
// this.use(require("cors")(this.opts.cors));
// }
// if (opts.perMessageDeflate) {
// this.opts.perMessageDeflate = Object.assign(
// {
// threshold: 1024,
// },
// opts.perMessageDeflate
// );
// }
// this.init();
}
protected abstract init();
/**
* Compute the pathname of the requests that are handled by the server
* @param options
* @protected
*/
protected _computePath(options: AttachOptions) {
let path = (options.path || "/engine.io").replace(/\/$/, "");
if (options.addTrailingSlash !== false) {
// normalize path
path += "/";
}
return path;
}
/**
* Returns a list of available transports for upgrade given a certain transport.
*
* @return {Array}
* @api public
*/
public upgrades(transport) {
if (!this.opts.allowUpgrades) return [];
return transports[transport].upgradesTo || [];
}
// /**
// * Verifies a request.
// *
// * @param {http.IncomingMessage}
// * @return {Boolean} whether the request is valid
// * @api private
// */
// protected verify(req, upgrade, fn) {
// // transport check
// const transport = req._query.transport;
// if (!~this.opts.transports.indexOf(transport)) {
// debug('unknown transport "%s"', transport);
// return fn(Server.errors.UNKNOWN_TRANSPORT, { transport });
// }
// // 'Origin' header check
// const isOriginInvalid = checkInvalidHeaderChar(req.headers.origin);
// if (isOriginInvalid) {
// const origin = req.headers.origin;
// req.headers.origin = null;
// debug("origin header invalid");
// return fn(Server.errors.BAD_REQUEST, {
// name: "INVALID_ORIGIN",
// origin,
// });
// }
// // sid check
// const sid = req._query.sid;
// if (sid) {
// if (!this.clients.hasOwnProperty(sid)) {
// debug('unknown sid "%s"', sid);
// return fn(Server.errors.UNKNOWN_SID, {
// sid,
// });
// }
// const previousTransport = this.clients[sid].transport.name;
// if (!upgrade && previousTransport !== transport) {
// debug("bad request: unexpected transport without upgrade");
// return fn(Server.errors.BAD_REQUEST, {
// name: "TRANSPORT_MISMATCH",
// transport,
// previousTransport,
// });
// }
// } else {
// // handshake is GET only
// if ("GET" !== req.method) {
// return fn(Server.errors.BAD_HANDSHAKE_METHOD, {
// method: req.method,
// });
// }
// if (transport === "websocket" && !upgrade) {
// debug("invalid transport upgrade");
// return fn(Server.errors.BAD_REQUEST, {
// name: "TRANSPORT_HANDSHAKE_ERROR",
// });
// }
// if (!this.opts.allowRequest) return fn();
// return this.opts.allowRequest(req, (message, success) => {
// if (!success) {
// return fn(Server.errors.FORBIDDEN, {
// message,
// });
// }
// fn();
// });
// }
// fn();
// }
/**
* Adds a new middleware.
*
* @example
* import helmet from "helmet";
*
* engine.use(helmet());
*
* @param fn
*/
public use(fn: Middleware) {
this.middlewares.push(fn);
}
/**
* Apply the middlewares to the request.
*
* @param req
* @param res
* @param callback
* @protected
*/
protected _applyMiddlewares(
req: any /*IncomingMessage*/,
res: any /*ServerResponse*/,
callback: () => void
) {
if (this.middlewares.length === 0) {
debug("no middleware to apply, skipping");
return callback();
}
const apply = (i) => {
debug("applying middleware n°%d", i + 1);
this.middlewares[i](req, res, () => {
if (i + 1 < this.middlewares.length) {
apply(i + 1);
} else {
callback();
}
});
};
apply(0);
}
/**
* Closes all clients.
*
* @api public
*/
public close() {
debug("closing all open clients");
for (let i in this.clients) {
if (this.clients.hasOwnProperty(i)) {
this.clients[i].close(true);
}
}
this.cleanup();
return this;
}
protected abstract cleanup();
/**
* generate a socket id.
* Overwrite this method to generate your custom socket id
*
* @param {Object} request object
* @api public
*/
public generateId(req) {
return req.id;
}
/**
* Handshakes a new client.
*
* @param {String} transport name
* @param {Object} request object
* @param {Function} closeConnection
*
* @api protected
*/
// protected async handshake(transportName, req, closeConnection) {
// @java-patch sync handshake
protected handshake(transportName, req, closeConnection) {
const protocol = req._query.EIO === "4" ? 4 : 3; // 3rd revision by default
if (protocol === 3 && !this.opts.allowEIO3) {
debug("unsupported protocol version");
this.emit("connection_error", {
req,
code: Server.errors.UNSUPPORTED_PROTOCOL_VERSION,
message:
Server.errorMessages[Server.errors.UNSUPPORTED_PROTOCOL_VERSION],
context: {
protocol,
},
});
closeConnection(Server.errors.UNSUPPORTED_PROTOCOL_VERSION);
return;
}
let id;
try {
id = this.generateId(req);
} catch (e) {
debug("error while generating an id");
this.emit("connection_error", {
req,
code: Server.errors.BAD_REQUEST,
message: Server.errorMessages[Server.errors.BAD_REQUEST],
context: {
name: "ID_GENERATION_ERROR",
error: e,
},
});
closeConnection(Server.errors.BAD_REQUEST);
return;
}
debug('handshaking client "%s"', id);
try {
// @java-patch reject not websocket
if ("websocket" !== transportName) {
throw new Error("Unsupport polling at MiaoScript!");
}
var transport = this.createTransport(transportName, req);
// if ("polling" === transportName) {
// transport.maxHttpBufferSize = this.opts.maxHttpBufferSize
// transport.httpCompression = this.opts.httpCompression
// } else if ("websocket" === transportName) {
transport.perMessageDeflate = this.opts.perMessageDeflate;
// }
if (req._query && req._query.b64) {
transport.supportsBinary = false;
} else {
transport.supportsBinary = true;
}
} catch (e) {
debug('error handshaking to transport "%s"', transportName);
this.emit("connection_error", {
req,
code: Server.errors.BAD_REQUEST,
message: Server.errorMessages[Server.errors.BAD_REQUEST],
context: {
name: "TRANSPORT_HANDSHAKE_ERROR",
error: e,
},
});
closeConnection(Server.errors.BAD_REQUEST);
return;
}
const socket = new Socket(id, this, transport, req, protocol);
transport.on("headers", (headers, req) => {
const isInitialRequest = !req._query.sid;
if (isInitialRequest) {
if (this.opts.cookie) {
headers["Set-Cookie"] = [
// @ts-ignore
// serialize(this.opts.cookie.name, id, this.opts.cookie),
];
}
this.emit("initial_headers", headers, req);
}
this.emit("headers", headers, req);
});
transport.onRequest(req);
this.clients[id] = socket;
this.clientsCount++;
socket.once("close", () => {
delete this.clients[id];
this.clientsCount--;
});
this.emit("connection", socket);
return transport;
}
protected abstract createTransport(transportName, req);
/**
* Protocol errors mappings.
*/
static errors = {
UNKNOWN_TRANSPORT: 0,
UNKNOWN_SID: 1,
BAD_HANDSHAKE_METHOD: 2,
BAD_REQUEST: 3,
FORBIDDEN: 4,
UNSUPPORTED_PROTOCOL_VERSION: 5,
};
static errorMessages = {
0: "Transport unknown",
1: "Session ID unknown",
2: "Bad handshake method",
3: "Bad request",
4: "Forbidden",
5: "Unsupported protocol version",
};
}
/**
* Exposes a subset of the http.ServerResponse interface, in order to be able to apply the middlewares to an upgrade
* request.
*
* @see https://nodejs.org/api/http.html#class-httpserverresponse
*/
class WebSocketResponse {
constructor(readonly req, readonly socket: any /*Duplex */) {
// temporarily store the response headers on the req object (see the "headers" event)
req[kResponseHeaders] = {};
}
public setHeader(name: string, value: any) {
this.req[kResponseHeaders][name] = value;
}
public getHeader(name: string) {
return this.req[kResponseHeaders][name];
}
public removeHeader(name: string) {
delete this.req[kResponseHeaders][name];
}
public write() {}
public writeHead() {}
public end() {
// we could return a proper error code, but the WebSocket client will emit an "error" event anyway.
this.socket.destroy();
}
}
export class Server extends BaseServer {
// public httpServer?: HttpServer
private ws: any;
/**
* Initialize websocket server
*
* @api protected
*/
protected init() {
if (!~this.opts.transports.indexOf("websocket")) return;
if (this.ws) this.ws.close();
this.ws = new this.opts.wsEngine({
noServer: true,
clientTracking: false,
perMessageDeflate: this.opts.perMessageDeflate,
maxPayload: this.opts.maxHttpBufferSize,
});
if (typeof this.ws.on === "function") {
this.ws.on("headers", (headersArray, req) => {
// note: 'ws' uses an array of headers, while Engine.IO uses an object (response.writeHead() accepts both formats)
// we could also try to parse the array and then sync the values, but that will be error-prone
const additionalHeaders = req[kResponseHeaders] || {};
delete req[kResponseHeaders];
const isInitialRequest = !req._query.sid;
if (isInitialRequest) {
this.emit("initial_headers", additionalHeaders, req);
}
this.emit("headers", additionalHeaders, req);
debug("writing headers: %j", additionalHeaders);
Object.keys(additionalHeaders).forEach((key) => {
headersArray.push(`${key}: ${additionalHeaders[key]}`);
});
});
}
}
protected cleanup() {
if (this.ws) {
debug("closing webSocketServer");
this.ws.close();
// don't delete this.ws because it can be used again if the http server starts listening again
}
}
/**
* Prepares a request by processing the query string.
*
* @api private
*/
private prepare(req) {
// try to leverage pre-existing `req._query` (e.g: from connect)
if (!req._query) {
req._query = ~req.url.indexOf("?") ? qs.parse(parse(req.url).query) : {};
}
}
protected createTransport(transportName, req) {
return new transports[transportName](req);
}
// /**
// * Handles an Engine.IO HTTP request.
// *
// * @param {IncomingMessage} req
// * @param {ServerResponse} res
// * @api public
// */
// public handleRequest(req: IncomingMessage, res: ServerResponse) {
// debug('handling "%s" http request "%s"', req.method, req.url);
// this.prepare(req);
// // @ts-ignore
// req.res = res;
// const callback = (errorCode, errorContext) => {
// if (errorCode !== undefined) {
// this.emit("connection_error", {
// req,
// code: errorCode,
// message: Server.errorMessages[errorCode],
// context: errorContext,
// });
// abortRequest(res, errorCode, errorContext);
// return;
// }
// // @ts-ignore
// if (req._query.sid) {
// debug("setting new request for existing client");
// // @ts-ignore
// this.clients[req._query.sid].transport.onRequest(req);
// } else {
// const closeConnection = (errorCode, errorContext) =>
// abortRequest(res, errorCode, errorContext);
// // @ts-ignore
// this.handshake(req._query.transport, req, closeConnection);
// }
// };
// this._applyMiddlewares(req, res, () => {
// this.verify(req, false, callback);
// });
// }
// /**
// * Handles an Engine.IO HTTP Upgrade.
// *
// * @api public
// */
// public handleUpgrade(
// req: IncomingMessage,
// socket: Duplex,
// upgradeHead: Buffer
// ) {
// this.prepare(req);
// const res = new WebSocketResponse(req, socket);
// this._applyMiddlewares(req, res as unknown as ServerResponse, () => {
// this.verify(req, true, (errorCode, errorContext) => {
// if (errorCode) {
// this.emit("connection_error", {
// req,
// code: errorCode,
// message: Server.errorMessages[errorCode],
// context: errorContext,
// });
// abortUpgrade(socket, errorCode, errorContext);
// return;
// }
// const head = Buffer.from(upgradeHead);
// upgradeHead = null;
// // some middlewares (like express-session) wait for the writeHead() call to flush their headers
// // see https://github.com/expressjs/session/blob/1010fadc2f071ddf2add94235d72224cf65159c6/index.js#L220-L244
// res.writeHead();
// // delegate to ws
// this.ws.handleUpgrade(req, socket, head, (websocket) => {
// this.onWebSocket(req, socket, websocket);
// });
// });
// });
// }
/**
* Called upon a ws.io connection.
*
* @param {ws.Socket} websocket
* @api private
*/
private onWebSocket(req: Request, socket, websocket: WebSocketClient) {
websocket.on("error", onUpgradeError);
if (
transports[req._query.transport] !== undefined &&
!transports[req._query.transport].prototype.handlesUpgrades
) {
debug("transport doesnt handle upgraded requests");
websocket.close();
return;
}
// get client id
const id = req._query.sid;
// keep a reference to the ws.Socket
req.websocket = websocket;
if (id) {
const client = this.clients[id];
if (!client) {
debug("upgrade attempt for closed client");
websocket.close();
} else if (client.upgrading) {
debug("transport has already been trying to upgrade");
websocket.close();
} else if (client.upgraded) {
debug("transport had already been upgraded");
websocket.close();
} else {
debug("upgrading existing transport");
// transport error handling takes over
websocket.removeListener("error", onUpgradeError);
const transport = this.createTransport(req._query.transport, req);
if (req._query && req._query.b64) {
transport.supportsBinary = false;
} else {
transport.supportsBinary = true;
}
transport.perMessageDeflate = this.opts.perMessageDeflate;
client.maybeUpgrade(transport);
}
} else {
// const closeConnection = (errorCode, errorContext) =>
// abortUpgrade(socket, errorCode, errorContext);
this.handshake(req._query.transport, req, () => {});
}
function onUpgradeError(...args) {
debug("websocket error before upgrade %s", ...args);
// websocket.close() not needed
}
}
/**
* Captures upgrade requests for a http.Server.
*
* @param {http.Server} server
* @param {Object} options
* @api public
*/
// public attach(server: HttpServer, options: AttachOptions = {}) {
// @java-patch
public attach(server, options: AttachOptions = {}) {
// const path = this._computePath(options);
// const destroyUpgradeTimeout = options.destroyUpgradeTimeout || 1000;
// function check(req) {
// // TODO use `path === new URL(...).pathname` in the next major release (ref: https://nodejs.org/api/url.html)
// return path === req.url.slice(0, path.length);
// }
// // cache and clean up listeners
// const listeners = server.listeners("request").slice(0);
// server.removeAllListeners("request");
server.on("close", this.close.bind(this));
// server.on("listening", this.init.bind(this))
// @java-patch transfer to Netty Server
server.on("connect", (request: Request, websocket: WebSocketClient) => {
console.debug("Engine.IO connect client from", request.url);
this.prepare(request);
this.onWebSocket(request, undefined, websocket);
});
// set server as ws server
this.ws = server;
// // add request handler
// server.on("request", (req, res) => {
// if (check(req)) {
// debug('intercepting request for path "%s"', path);
// this.handleRequest(req, res);
// } else {
// let i = 0;
// const l = listeners.length;
// for (; i < l; i++) {
// listeners[i].call(server, req, res);
// }
// }
// });
// if (~this.opts.transports.indexOf("websocket")) {
// server.on("upgrade", (req, socket, head) => {
// if (check(req)) {
// this.handleUpgrade(req, socket, head);
// } else if (false !== options.destroyUpgrade) {
// // default node behavior is to disconnect when no handlers
// // but by adding a handler, we prevent that
// // and if no eio thing handles the upgrade
// // then the socket needs to die!
// setTimeout(function () {
// // @ts-ignore
// if (socket.writable && socket.bytesWritten <= 0) {
// socket.on("error", (e) => {
// debug("error while destroying upgrade: %s", e.message);
// });
// return socket.end();
// }
// }, destroyUpgradeTimeout);
// }
// });
// }
}
}
// /**
// * Close the HTTP long-polling request
// *
// * @param res - the response object
// * @param errorCode - the error code
// * @param errorContext - additional error context
// *
// * @api private
// */
// function abortRequest(res, errorCode, errorContext) {
// const statusCode = errorCode === Server.errors.FORBIDDEN ? 403 : 400;
// const message =
// errorContext && errorContext.message
// ? errorContext.message
// : Server.errorMessages[errorCode];
// res.writeHead(statusCode, { "Content-Type": "application/json" });
// res.end(
// JSON.stringify({
// code: errorCode,
// message,
// })
// );
// }
// /**
// * Close the WebSocket connection
// *
// * @param {net.Socket} socket
// * @param {string} errorCode - the error code
// * @param {object} errorContext - additional error context
// *
// * @api private
// */
// function abortUpgrade(
// socket,
// errorCode,
// errorContext: { message?: string } = {}
// ) {
// socket.on("error", () => {
// debug("ignoring error from closed connection");
// });
// if (socket.writable) {
// const message = errorContext.message || Server.errorMessages[errorCode];
// const length = Buffer.byteLength(message);
// socket.write(
// "HTTP/1.1 400 Bad Request\r\n" +
// "Connection: close\r\n" +
// "Content-type: text/html\r\n" +
// "Content-Length: " +
// length +
// "\r\n" +
// "\r\n" +
// message
// );
// }
// socket.destroy();
// }
/* eslint-disable */
// /**
// * From https://github.com/nodejs/node/blob/v8.4.0/lib/_http_common.js#L303-L354
// *
// * True if val contains an invalid field-vchar
// * field-value = *( field-content / obs-fold )
// * field-content = field-vchar [ 1*( SP / HTAB ) field-vchar ]
// * field-vchar = VCHAR / obs-text
// *
// * checkInvalidHeaderChar() is currently designed to be inlinable by v8,
// * so take care when making changes to the implementation so that the source
// * code size does not exceed v8's default max_inlined_source_size setting.
// **/
// // prettier-ignore
// const validHdrChars = [
// 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, // 0 - 15
// 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 16 - 31
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 32 - 47
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 48 - 63
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 64 - 79
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 80 - 95
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 96 - 111
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, // 112 - 127
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 128 ...
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
// 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 // ... 255
// ]
// function checkInvalidHeaderChar(val) {
// val += "";
// if (val.length < 1) return false;
// if (!validHdrChars[val.charCodeAt(0)]) {
// debug('invalid header, index 0, char "%s"', val.charCodeAt(0));
// return true;
// }
// if (val.length < 2) return false;
// if (!validHdrChars[val.charCodeAt(1)]) {
// debug('invalid header, index 1, char "%s"', val.charCodeAt(1));
// return true;
// }
// if (val.length < 3) return false;
// if (!validHdrChars[val.charCodeAt(2)]) {
// debug('invalid header, index 2, char "%s"', val.charCodeAt(2));
// return true;
// }
// if (val.length < 4) return false;
// if (!validHdrChars[val.charCodeAt(3)]) {
// debug('invalid header, index 3, char "%s"', val.charCodeAt(3));
// return true;
// }
// for (let i = 4; i < val.length; ++i) {
// if (!validHdrChars[val.charCodeAt(i)]) {
// debug('invalid header, index "%i", char "%s"', i, val.charCodeAt(i));
// return true;
// }
// }
// return false;
// }