std/ws

ws

ws module is made to provide helpers to create WebSocket client/server.

Usage

Server

// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
import { serve } from "https://deno.land/std/http/server.ts";
import {
  acceptWebSocket,
  isWebSocketCloseEvent,
  isWebSocketPingEvent,
  WebSocket,
} from "https://deno.land/std/ws/mod.ts";

async function handleWs(sock: WebSocket) {
  console.log("socket connected!");
  try {
    for await (const ev of sock) {
      if (typeof ev === "string") {
        // text message
        console.log("ws:Text", ev);
        await sock.send(ev);
      } else if (ev instanceof Uint8Array) {
        // binary message
        console.log("ws:Binary", ev);
      } else if (isWebSocketPingEvent(ev)) {
        const [, body] = ev;
        // ping
        console.log("ws:Ping", body);
      } else if (isWebSocketCloseEvent(ev)) {
        // close
        const { code, reason } = ev;
        console.log("ws:Close", code, reason);
      }
    }
  } catch (err) {
    console.error(`failed to receive frame: ${err}`);

    if (!sock.isClosed) {
      await sock.close(1000).catch(console.error);
    }
  }
}

if (import.meta.main) {
  /** websocket echo server */
  const port = Deno.args[0] || "8080";
  console.log(`websocket server is running on :${port}`);
  for await (const req of serve(`:${port}`)) {
    const { conn, r: bufReader, w: bufWriter, headers } = req;
    acceptWebSocket({
      conn,
      bufReader,
      bufWriter,
      headers,
    })
      .then(handleWs)
      .catch(async (err) => {
        console.error(`failed to accept websocket: ${err}`);
        await req.respond({ status: 400 });
      });
  }
}

Client

import {
  connectWebSocket,
  isWebSocketCloseEvent,
  isWebSocketPingEvent,
  isWebSocketPongEvent,
} from "https://deno.land/std/ws/mod.ts";
import { encode } from "https://deno.land/std/encoding/utf8.ts";
import { BufReader } from "https://deno.land/std/io/bufio.ts";
import { TextProtoReader } from "https://deno.land/std/textproto/mod.ts";
import { blue, green, red, yellow } from "https://deno.land/std/fmt/colors.ts";

const endpoint = Deno.args[0] || "ws://127.0.0.1:8080";
/** simple websocket cli */
try {
  const sock = await connectWebSocket(endpoint);
  console.log(green("ws connected! (type 'close' to quit)"));

  const messages = async (): Promise<void> => {
    for await (const msg of sock) {
      if (typeof msg === "string") {
        console.log(yellow(`< ${msg}`));
      } else if (isWebSocketPingEvent(msg)) {
        console.log(blue("< ping"));
      } else if (isWebSocketPongEvent(msg)) {
        console.log(blue("< pong"));
      } else if (isWebSocketCloseEvent(msg)) {
        console.log(red(`closed: code=${msg.code}, reason=${msg.reason}`));
      }
    }
  };

  const cli = async (): Promise<void> => {
    const tpr = new TextProtoReader(new BufReader(Deno.stdin));
    while (true) {
      await Deno.stdout.write(encode("> "));
      const line = await tpr.readLine();
      if (line === null || line === "close") {
        break;
      } else if (line === "ping") {
        await sock.ping();
      } else {
        await sock.send(line);
      }
    }
  };

  await Promise.race([messages(), cli()]).catch(console.error);

  if (!sock.isClosed) {
    await sock.close(1000).catch(console.error);
  }
} catch (err) {
  console.error(red(`Could not connect to WebSocket: '${err}'`));
}

Deno.exit(0);

API

isWebSocketCloseEvent

Returns true if input value is a WebSocketCloseEvent, false otherwise.

isWebSocketPingEvent

Returns true if input value is a WebSocketPingEvent, false otherwise.

isWebSocketPongEvent

Returns true if input value is a WebSocketPongEvent, false otherwise.

unmask

Unmask masked WebSocket payload.

writeFrame

Write WebSocket frame to inputted writer.

readFrame

Read WebSocket frame from inputted BufReader.

createMask

Create mask from the client to the server with random 32bit number.

acceptable

Returns true if input headers are usable for WebSocket, otherwise false

createSecAccept

Create value of Sec-WebSocket-Accept header from inputted nonce.

acceptWebSocket

Upgrade inputted TCP connection into WebSocket connection.

createSecKey

Returns base64 encoded 16 bytes string for Sec-WebSocket-Key header.

connectWebSocket

Connect to WebSocket endpoint url with inputted endpoint string and headers.

• note: Endpoint must be acceptable for URL.