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367import { ConnInfo, getLogger, Handler } from "../../../deps.ts";
import { EventEmitter } from "../../event-emitter/mod.ts";
import { Socket } from "./socket.ts";
import { Polling } from "./transports/polling.ts";
import { WS } from "./transports/websocket.ts";
import { addCorsHeaders, CorsOptions } from "./cors.ts";
import { Transport } from "./transport.ts";
import { generateId } from "./util.ts";
const TRANSPORTS = ["polling", "websocket"];
export interface ServerOptions {
/**
* Name of the request path to handle
* @default "/engine.io/"
*/
path: string;
/**
* Duration in milliseconds without a pong packet to consider the connection closed
* @default 20000
*/
pingTimeout: number;
/**
* Duration in milliseconds before sending a new ping packet
* @default 25000
*/
pingInterval: number;
/**
* Duration in milliseconds before an uncompleted transport upgrade is cancelled
* @default 10000
*/
upgradeTimeout: number;
/**
* Maximum size in bytes or number of characters a message can be, before closing the session (to avoid DoS).
* @default 1e6 (1 MB)
*/
maxHttpBufferSize: number;
/**
* A function that receives a given handshake or upgrade request as its first parameter,
* and can decide whether to continue or not.
*/
allowRequest?: (
req: Request,
connInfo: ConnInfo,
) => Promise<void>;
/**
* The options related to Cross-Origin Resource Sharing (CORS)
*/
cors?: CorsOptions;
/**
* A function that allows to edit the response headers of the handshake request
*/
editHandshakeHeaders?: (
responseHeaders: Headers,
req: Request,
connInfo: ConnInfo,
) => void | Promise<void>;
/**
* A function that allows to edit the response headers of all requests
*/
editResponseHeaders?: (
responseHeaders: Headers,
req: Request,
connInfo: ConnInfo,
) => void | Promise<void>;
}
interface ConnectionError {
req: Request;
code: number;
message: string;
context: Record<string, unknown>;
}
interface ServerReservedEvents {
connection: (socket: Socket, request: Request, connInfo: ConnInfo) => void;
connection_error: (err: ConnectionError) => void;
}
const enum ERROR_CODES {
UNKNOWN_TRANSPORT = 0,
UNKNOWN_SID,
BAD_HANDSHAKE_METHOD,
BAD_REQUEST,
FORBIDDEN,
UNSUPPORTED_PROTOCOL_VERSION,
}
const ERROR_MESSAGES = new Map<ERROR_CODES, string>([
[ERROR_CODES.UNKNOWN_TRANSPORT, "Transport unknown"],
[ERROR_CODES.UNKNOWN_SID, "Session ID unknown"],
[ERROR_CODES.BAD_HANDSHAKE_METHOD, "Bad handshake method"],
[ERROR_CODES.BAD_REQUEST, "Bad request"],
[ERROR_CODES.FORBIDDEN, "Forbidden"],
[ERROR_CODES.UNSUPPORTED_PROTOCOL_VERSION, "Unsupported protocol version"],
]);
export class Server extends EventEmitter<
Record<never, never>,
Record<never, never>,
ServerReservedEvents
> {
public readonly opts: ServerOptions;
private clients: Map<string, Socket> = new Map();
constructor(opts: Partial<ServerOptions> = {}) {
super();
this.opts = Object.assign(
{
path: "/engine.io/",
pingTimeout: 20000,
pingInterval: 25000,
upgradeTimeout: 10000,
maxHttpBufferSize: 1e6,
},
opts,
);
}
/**
* Returns a request handler.
*
* @param additionalHandler - another handler which will receive the request if the path does not match
*/
public handler(additionalHandler?: Handler) {
return (req: Request, connInfo: ConnInfo): Response | Promise<Response> => {
const url = new URL(req.url);
if (url.pathname === this.opts.path) {
return this.handleRequest(req, connInfo, url);
} else if (additionalHandler) {
return additionalHandler(req, connInfo);
} else {
return new Response(null, { status: 404 });
}
};
}
/**
* Handles an HTTP request.
*
* @param req
* @param connInfo
* @param url
* @private
*/
private async handleRequest(
req: Request,
connInfo: ConnInfo,
url: URL,
): Promise<Response> {
getLogger("engine.io").debug(`[server] handling ${req.method} ${req.url}`);
const responseHeaders = new Headers();
if (this.opts.cors) {
addCorsHeaders(responseHeaders, this.opts.cors, req);
if (req.method === "OPTIONS") {
return new Response(null, { status: 204, headers: responseHeaders });
}
}
if (this.opts.editResponseHeaders) {
await this.opts.editResponseHeaders(responseHeaders, req, connInfo);
}
try {
await this.verify(req, url);
} catch (err) {
const { code, context } = err as {
code: ERROR_CODES;
context: Record<string, unknown>;
};
const message = ERROR_MESSAGES.get(code)!;
this.emitReserved("connection_error", {
req,
code,
message,
context,
});
const body = JSON.stringify({
code,
message,
});
responseHeaders.set("Content-Type", "application/json");
return new Response(body, {
status: 400,
headers: responseHeaders,
});
}
if (this.opts.allowRequest) {
try {
await this.opts.allowRequest(req, connInfo);
} catch (reason) {
this.emitReserved("connection_error", {
req,
code: ERROR_CODES.FORBIDDEN,
message: ERROR_MESSAGES.get(ERROR_CODES.FORBIDDEN)!,
context: {
message: reason,
},
});
const body = JSON.stringify({
code: ERROR_CODES.FORBIDDEN,
message: reason,
});
responseHeaders.set("Content-Type", "application/json");
return new Response(body, {
status: 403,
headers: responseHeaders,
});
}
}
const sid = url.searchParams.get("sid");
if (sid) {
// the client must exist since we have checked it in the verify method
const socket = this.clients.get(sid)!;
if (req.headers.has("upgrade")) {
const transport = new WS(this.opts);
const promise = transport.onRequest(req);
socket._maybeUpgrade(transport);
return promise;
}
getLogger("engine.io").debug(
"[server] setting new request for existing socket",
);
return socket.transport.onRequest(req, responseHeaders);
} else {
return this.handshake(req, connInfo, responseHeaders);
}
}
/**
* Verifies a request.
*
* @param req
* @param url
* @private
*/
private verify(req: Request, url: URL): Promise<void> {
const transport = url.searchParams.get("transport") || "";
if (!TRANSPORTS.includes(transport)) {
getLogger("engine.io").debug(`unknown transport "${transport}"`);
return Promise.reject({
code: ERROR_CODES.UNKNOWN_TRANSPORT,
context: {
transport,
},
});
}
const sid = url.searchParams.get("sid");
if (sid) {
const client = this.clients.get(sid);
if (!client) {
getLogger("engine.io").debug(`[server] unknown client with sid ${sid}`);
return Promise.reject({
code: ERROR_CODES.UNKNOWN_SID,
context: {
sid,
},
});
}
const previousTransport = client.transport.name;
if (previousTransport === "websocket") {
getLogger("engine.io").debug(
"[server] unexpected transport without upgrade",
);
return Promise.reject(
{
code: ERROR_CODES.BAD_REQUEST,
context: {
name: "TRANSPORT_MISMATCH",
transport,
previousTransport,
},
},
);
}
} else {
// handshake is GET only
if (req.method !== "GET") {
return Promise.reject({
code: ERROR_CODES.BAD_HANDSHAKE_METHOD,
context: {
method: req.method,
},
});
}
const protocol = url.searchParams.get("EIO") === "4" ? 4 : 3; // 3rd revision by default
if (protocol === 3) {
return Promise.reject({
code: ERROR_CODES.UNSUPPORTED_PROTOCOL_VERSION,
context: {
protocol,
},
});
}
}
return Promise.resolve();
}
/**
* Handshakes a new client.
*
* @param req
* @param connInfo
* @param responseHeaders
* @private
*/
private async handshake(
req: Request,
connInfo: ConnInfo,
responseHeaders: Headers,
): Promise<Response> {
const id = generateId();
let transport: Transport;
if (req.headers.has("upgrade")) {
transport = new WS(this.opts);
} else {
transport = new Polling(this.opts);
}
getLogger("engine.io").info(`[server] new socket ${id}`);
const socket = new Socket(id, this.opts, transport);
this.clients.set(id, socket);
socket.once("close", (reason) => {
getLogger("engine.io").info(
`[server] socket ${id} closed due to ${reason}`,
);
this.clients.delete(id);
});
if (this.opts.editHandshakeHeaders) {
await this.opts.editHandshakeHeaders(responseHeaders, req, connInfo);
}
const promise = transport.onRequest(req, responseHeaders);
this.emitReserved("connection", socket, req, connInfo);
return promise;
}
/**
* Closes all clients.
*/
public close() {
getLogger("engine.io").debug("[server] closing all open clients");
this.clients.forEach((client) => client.close());
}
}