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mod.ts
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// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
import { decode, encode } from "../strings/strings.ts";
type Conn = Deno.Conn;
type Writer = Deno.Writer;
import { BufReader, BufWriter } from "../io/bufio.ts";
import { readLong, readShort, sliceLongToBytes } from "../io/ioutil.ts";
import { Sha1 } from "./sha1.ts";
import { writeResponse } from "../http/server.ts";
import { TextProtoReader } from "../textproto/mod.ts";
export enum OpCode {
Continue = 0x0,
TextFrame = 0x1,
BinaryFrame = 0x2,
Close = 0x8,
Ping = 0x9,
Pong = 0xa
}
export type WebSocketEvent =
| string
| Uint8Array
| WebSocketCloseEvent
| WebSocketPingEvent
| WebSocketPongEvent;
export interface WebSocketCloseEvent {
code: number;
reason?: string;
}
export function isWebSocketCloseEvent(a: WebSocketEvent): a is WebSocketCloseEvent {
return typeof a === "object" && a.hasOwnProperty("code");
}
export type WebSocketPingEvent = ["ping", Uint8Array];
export function isWebSocketPingEvent(a: WebSocketEvent): a is WebSocketPingEvent {
return Array.isArray(a) && a[0] === "ping" && a[1] instanceof Uint8Array;
}
export type WebSocketPongEvent = ["pong", Uint8Array];
export function isWebSocketPongEvent(a: WebSocketEvent): a is WebSocketPongEvent {
return Array.isArray(a) && a[0] === "pong" && a[1] instanceof Uint8Array;
}
export type WebSocketMessage = string | Uint8Array;
// TODO move this to common/util module
export function append(a: Uint8Array, b: Uint8Array): Uint8Array {
if (a == null || !a.length) {
return b;
}
if (b == null || !b.length) {
return a;
}
const output = new Uint8Array(a.length + b.length);
output.set(a, 0);
output.set(b, a.length);
return output;
}
export class SocketClosedError extends Error {}
export interface WebSocketFrame {
isLastFrame: boolean;
opcode: OpCode;
mask?: Uint8Array;
payload: Uint8Array;
}
export interface WebSocket {
readonly conn: Conn;
readonly isClosed: boolean;
receive(): AsyncIterableIterator<WebSocketEvent>;
send(data: WebSocketMessage): Promise<void>;
ping(data?: WebSocketMessage): Promise<void>;
close(code: number, reason?: string): Promise<void>;
}
/** Unmask masked websocket payload */
export function unmask(payload: Uint8Array, mask?: Uint8Array): void {
if (mask) {
for (let i = 0, len = payload.length; i < len; i++) {
payload[i] ^= mask![i & 3];
}
}
}
/** Write websocket frame to given writer */
export async function writeFrame(
frame: WebSocketFrame,
writer: Writer
): Promise<void> {
const payloadLength = frame.payload.byteLength;
let header: Uint8Array;
const hasMask = frame.mask ? 0x80 : 0;
if (frame.mask && frame.mask.byteLength !== 4) {
throw new Error(
"invalid mask. mask must be 4 bytes: length=" + frame.mask.byteLength
);
}
if (payloadLength < 126) {
header = new Uint8Array([0x80 | frame.opcode, hasMask | payloadLength]);
} else if (payloadLength < 0xffff) {
header = new Uint8Array([
0x80 | frame.opcode,
hasMask | 0b01111110,
payloadLength >>> 8,
payloadLength & 0x00ff
]);
} else {
header = new Uint8Array([
0x80 | frame.opcode,
hasMask | 0b01111111,
...sliceLongToBytes(payloadLength)
]);
}
if (frame.mask) {
header = append(header, frame.mask);
}
unmask(frame.payload, frame.mask);
header = append(header, frame.payload);
const w = BufWriter.create(writer);
await w.write(header);
const err = await w.flush();
if (err) throw err;
}
/** Read websocket frame from given BufReader */
export async function readFrame(buf: BufReader): Promise<WebSocketFrame> {
let b = await buf.readByte();
let isLastFrame = false;
switch (b >>> 4) {
case 0b1000:
isLastFrame = true;
break;
case 0b0000:
isLastFrame = false;
break;
default:
throw new Error("invalid signature");
}
const opcode = b & 0x0f;
// has_mask & payload
b = await buf.readByte();
const hasMask = b >>> 7;
let payloadLength = b & 0b01111111;
if (payloadLength === 126) {
payloadLength = await readShort(buf);
} else if (payloadLength === 127) {
payloadLength = await readLong(buf);
}
// mask
let mask;
if (hasMask) {
mask = new Uint8Array(4);
await buf.readFull(mask);
}
// payload
const payload = new Uint8Array(payloadLength);
await buf.readFull(payload);
return {
isLastFrame,
opcode,
mask,
payload
};
}
// Create client-to-server mask, random 32bit number
function createMask(): Uint8Array {
// TODO: use secure and immutable random function. Crypto.getRandomValues()
const arr = Array.from({ length: 4 }).map(
(): number => Math.round(Math.random() * 0xff)
);
return new Uint8Array(arr);
}
class WebSocketImpl implements WebSocket {
private readonly mask?: Uint8Array;
private readonly bufReader: BufReader;
private readonly bufWriter: BufWriter;
constructor(
readonly conn: Conn,
opts: {
bufReader?: BufReader;
bufWriter?: BufWriter;
mask?: Uint8Array;
} = {}
) {
this.mask = opts.mask || createMask();
this.bufReader = opts.bufReader || new BufReader(conn);
this.bufWriter = opts.bufWriter || new BufWriter(conn);
}
async *receive(): AsyncIterableIterator<WebSocketEvent> {
let frames: WebSocketFrame[] = [];
let payloadsLength = 0;
while (true) {
const frame = await readFrame(this.bufReader);
unmask(frame.payload, frame.mask);
switch (frame.opcode) {
case OpCode.TextFrame:
case OpCode.BinaryFrame:
case OpCode.Continue:
frames.push(frame);
payloadsLength += frame.payload.length;
if (frame.isLastFrame) {
const concat = new Uint8Array(payloadsLength);
let offs = 0;
for (const frame of frames) {
concat.set(frame.payload, offs);
offs += frame.payload.length;
}
if (frames[0].opcode === OpCode.TextFrame) {
// text
yield decode(concat);
} else {
// binary
yield concat;
}
frames = [];
payloadsLength = 0;
}
break;
case OpCode.Close:
// [0x12, 0x34] -> 0x1234
const code = (frame.payload[0] << 8) | frame.payload[1];
const reason = decode(
frame.payload.subarray(2, frame.payload.length)
);
await this.close(code, reason);
yield { code, reason };
return;
case OpCode.Ping:
await writeFrame(
{
opcode: OpCode.Pong,
payload: frame.payload,
isLastFrame: true
},
this.bufWriter
);
yield ["ping", frame.payload] as WebSocketPingEvent;
break;
case OpCode.Pong:
yield ["pong", frame.payload] as WebSocketPongEvent;
break;
default:
}
}
}
async send(data: WebSocketMessage): Promise<void> {
if (this.isClosed) {
throw new SocketClosedError("socket has been closed");
}
const opcode =
typeof data === "string" ? OpCode.TextFrame : OpCode.BinaryFrame;
const payload = typeof data === "string" ? encode(data) : data;
const isLastFrame = true;
await writeFrame(
{
isLastFrame,
opcode,
payload,
mask: this.mask
},
this.bufWriter
);
}
async ping(data: WebSocketMessage = ""): Promise<void> {
const payload = typeof data === "string" ? encode(data) : data;
await writeFrame(
{
isLastFrame: true,
opcode: OpCode.Ping,
mask: this.mask,
payload
},
this.bufWriter
);
}
private _isClosed = false;
get isClosed(): boolean {
return this._isClosed;
}
async close(code: number, reason?: string): Promise<void> {
try {
const header = [code >>> 8, code & 0x00ff];
let payload: Uint8Array;
if (reason) {
const reasonBytes = encode(reason);
payload = new Uint8Array(2 + reasonBytes.byteLength);
payload.set(header);
payload.set(reasonBytes, 2);
} else {
payload = new Uint8Array(header);
}
await writeFrame(
{
isLastFrame: true,
opcode: OpCode.Close,
mask: this.mask,
payload
},
this.bufWriter
);
} catch (e) {
throw e;
} finally {
this.ensureSocketClosed();
}
}
private ensureSocketClosed(): void {
if (this.isClosed) {
return;
}
try {
this.conn.close();
} catch (e) {
console.error(e);
} finally {
this._isClosed = true;
}
}
}
/** Return whether given headers is acceptable for websocket */
export function acceptable(req: { headers: Headers }): boolean {
const upgrade = req.headers.get("upgrade");
if (!upgrade || upgrade.toLowerCase() !== "websocket") {
return false;
}
const secKey = req.headers.get("sec-websocket-key");
return (
req.headers.has("sec-websocket-key") &&
typeof secKey === "string" &&
secKey.length > 0
);
}
const kGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
/** Create sec-websocket-accept header value with given nonce */
export function createSecAccept(nonce: string): string {
const sha1 = new Sha1();
sha1.update(nonce + kGUID);
const bytes = sha1.digest();
return btoa(String.fromCharCode.apply(String, bytes));
}
/** Upgrade given TCP connection into websocket connection */
export async function acceptWebSocket(req: {
conn: Conn;
bufWriter: BufWriter;
bufReader: BufReader;
headers: Headers;
}): Promise<WebSocket> {
const { conn, headers, bufReader, bufWriter } = req;
if (acceptable(req)) {
const sock = new WebSocketImpl(conn, { bufReader, bufWriter });
const secKey = headers.get("sec-websocket-key");
if (typeof secKey !== "string") {
throw new Error("sec-websocket-key is not provided");
}
const secAccept = createSecAccept(secKey);
await writeResponse(bufWriter, {
status: 101,
headers: new Headers({
Upgrade: "websocket",
Connection: "Upgrade",
"Sec-WebSocket-Accept": secAccept
})
});
return sock;
}
throw new Error("request is not acceptable");
}
const kSecChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-.~_";
/** Create WebSocket-Sec-Key. Base64 encoded 16 bytes string */
export function createSecKey(): string {
let key = "";
for (let i = 0; i < 16; i++) {
const j = Math.round(Math.random() * kSecChars.length);
key += kSecChars[j];
}
return btoa(key);
}
/** Connect to given websocket endpoint url. Endpoint must be acceptable for URL */
export async function connectWebSocket(
endpoint: string,
headers: Headers = new Headers()
): Promise<WebSocket> {
const url = new URL(endpoint);
const { hostname, pathname, searchParams } = url;
let port = url.port;
if (!url.port) {
if (url.protocol === "http" || url.protocol === "ws") {
port = "80";
} else if (url.protocol === "https" || url.protocol === "wss") {
throw new Error("currently https/wss is not supported");
}
}
const conn = await Deno.dial("tcp", `${hostname}:${port}`);
const abortHandshake = (err: Error): void => {
conn.close();
throw err;
};
const bufWriter = new BufWriter(conn);
const bufReader = new BufReader(conn);
await bufWriter.write(
encode(`GET ${pathname}?${searchParams || ""} HTTP/1.1\r\n`)
);
const key = createSecKey();
if (!headers.has("host")) {
headers.set("host", hostname);
}
headers.set("upgrade", "websocket");
headers.set("connection", "upgrade");
headers.set("sec-websocket-key", key);
let headerStr = "";
for (const [key, value] of headers) {
headerStr += `${key}: ${value}\r\n`;
}
headerStr += "\r\n";
await bufWriter.write(encode(headerStr));
let err, statusLine, responseHeaders;
err = await bufWriter.flush();
if (err) {
throw new Error("ws: failed to send handshake: " + err);
}
const tpReader = new TextProtoReader(bufReader);
[statusLine, err] = await tpReader.readLine();
if (err) {
abortHandshake(new Error("ws: failed to read status line: " + err));
}
const m = statusLine.match(/^(.+?) (.+?) (.+?)$/);
if (!m) {
abortHandshake(new Error("ws: invalid status line: " + statusLine));
}
const version: string = m![1];
const statusCode: string = m![2];
if (version !== "HTTP/1.1" || statusCode !== "101") {
abortHandshake(
new Error(
`ws: server didn't accept handshake: version=${version}, statusCode=${statusCode}`
)
);
}
[responseHeaders, err] = await tpReader.readMIMEHeader();
if (err) {
abortHandshake(new Error("ws: failed to parse response headers: " + err));
}
const expectedSecAccept = createSecAccept(key);
const secAccept = responseHeaders.get("sec-websocket-accept");
if (secAccept !== expectedSecAccept) {
abortHandshake(
new Error(
`ws: unexpected sec-websocket-accept header: expected=${expectedSecAccept}, actual=${secAccept}`
)
);
}
return new WebSocketImpl(conn, {
bufWriter,
bufReader
});
}