514 lines
12 KiB
JavaScript
514 lines
12 KiB
JavaScript
'use strict';
|
|
|
|
const stream = require('stream');
|
|
|
|
const PerMessageDeflate = require('./permessage-deflate');
|
|
const bufferUtil = require('./buffer-util');
|
|
const validation = require('./validation');
|
|
const constants = require('./constants');
|
|
|
|
const GET_INFO = 0;
|
|
const GET_PAYLOAD_LENGTH_16 = 1;
|
|
const GET_PAYLOAD_LENGTH_64 = 2;
|
|
const GET_MASK = 3;
|
|
const GET_DATA = 4;
|
|
const INFLATING = 5;
|
|
|
|
/**
|
|
* HyBi Receiver implementation.
|
|
*
|
|
* @extends stream.Writable
|
|
*/
|
|
class Receiver extends stream.Writable {
|
|
/**
|
|
* Creates a Receiver instance.
|
|
*
|
|
* @param {String} binaryType The type for binary data
|
|
* @param {Object} extensions An object containing the negotiated extensions
|
|
* @param {Number} maxPayload The maximum allowed message length
|
|
*/
|
|
constructor (binaryType, extensions, maxPayload) {
|
|
super();
|
|
|
|
this._binaryType = binaryType || constants.BINARY_TYPES[0];
|
|
this[constants.kWebSocket] = undefined;
|
|
this._extensions = extensions || {};
|
|
this._maxPayload = maxPayload | 0;
|
|
|
|
this._bufferedBytes = 0;
|
|
this._buffers = [];
|
|
|
|
this._compressed = false;
|
|
this._payloadLength = 0;
|
|
this._mask = undefined;
|
|
this._fragmented = 0;
|
|
this._masked = false;
|
|
this._fin = false;
|
|
this._opcode = 0;
|
|
|
|
this._totalPayloadLength = 0;
|
|
this._messageLength = 0;
|
|
this._fragments = [];
|
|
|
|
this._state = GET_INFO;
|
|
this._loop = false;
|
|
}
|
|
|
|
/**
|
|
* Implements `Writable.prototype._write()`.
|
|
*
|
|
* @param {Buffer} chunk The chunk of data to write
|
|
* @param {String} encoding The character encoding of `chunk`
|
|
* @param {Function} cb Callback
|
|
*/
|
|
_write (chunk, encoding, cb) {
|
|
if (this._opcode === 0x08) return cb();
|
|
|
|
this._bufferedBytes += chunk.length;
|
|
this._buffers.push(chunk);
|
|
this.startLoop(cb);
|
|
}
|
|
|
|
/**
|
|
* Consumes `n` bytes from the buffered data.
|
|
*
|
|
* @param {Number} n The number of bytes to consume
|
|
* @return {Buffer} The consumed bytes
|
|
* @private
|
|
*/
|
|
consume (n) {
|
|
this._bufferedBytes -= n;
|
|
|
|
if (n === this._buffers[0].length) return this._buffers.shift();
|
|
|
|
if (n < this._buffers[0].length) {
|
|
const buf = this._buffers[0];
|
|
this._buffers[0] = buf.slice(n);
|
|
return buf.slice(0, n);
|
|
}
|
|
|
|
const dst = Buffer.allocUnsafe(n);
|
|
|
|
do {
|
|
const buf = this._buffers[0];
|
|
|
|
if (n >= buf.length) {
|
|
this._buffers.shift().copy(dst, dst.length - n);
|
|
} else {
|
|
buf.copy(dst, dst.length - n, 0, n);
|
|
this._buffers[0] = buf.slice(n);
|
|
}
|
|
|
|
n -= buf.length;
|
|
} while (n > 0);
|
|
|
|
return dst;
|
|
}
|
|
|
|
/**
|
|
* Starts the parsing loop.
|
|
*
|
|
* @param {Function} cb Callback
|
|
* @private
|
|
*/
|
|
startLoop (cb) {
|
|
var err;
|
|
this._loop = true;
|
|
|
|
do {
|
|
switch (this._state) {
|
|
case GET_INFO:
|
|
err = this.getInfo();
|
|
break;
|
|
case GET_PAYLOAD_LENGTH_16:
|
|
err = this.getPayloadLength16();
|
|
break;
|
|
case GET_PAYLOAD_LENGTH_64:
|
|
err = this.getPayloadLength64();
|
|
break;
|
|
case GET_MASK:
|
|
this.getMask();
|
|
break;
|
|
case GET_DATA:
|
|
err = this.getData(cb);
|
|
break;
|
|
default: // `INFLATING`
|
|
this._loop = false;
|
|
return;
|
|
}
|
|
} while (this._loop);
|
|
|
|
cb(err);
|
|
}
|
|
|
|
/**
|
|
* Reads the first two bytes of a frame.
|
|
*
|
|
* @return {(RangeError|undefined)} A possible error
|
|
* @private
|
|
*/
|
|
getInfo () {
|
|
if (this._bufferedBytes < 2) {
|
|
this._loop = false;
|
|
return;
|
|
}
|
|
|
|
const buf = this.consume(2);
|
|
|
|
if ((buf[0] & 0x30) !== 0x00) {
|
|
this._loop = false;
|
|
return error(RangeError, 'RSV2 and RSV3 must be clear', true, 1002);
|
|
}
|
|
|
|
const compressed = (buf[0] & 0x40) === 0x40;
|
|
|
|
if (compressed && !this._extensions[PerMessageDeflate.extensionName]) {
|
|
this._loop = false;
|
|
return error(RangeError, 'RSV1 must be clear', true, 1002);
|
|
}
|
|
|
|
this._fin = (buf[0] & 0x80) === 0x80;
|
|
this._opcode = buf[0] & 0x0f;
|
|
this._payloadLength = buf[1] & 0x7f;
|
|
|
|
if (this._opcode === 0x00) {
|
|
if (compressed) {
|
|
this._loop = false;
|
|
return error(RangeError, 'RSV1 must be clear', true, 1002);
|
|
}
|
|
|
|
if (!this._fragmented) {
|
|
this._loop = false;
|
|
return error(RangeError, 'invalid opcode 0', true, 1002);
|
|
}
|
|
|
|
this._opcode = this._fragmented;
|
|
} else if (this._opcode === 0x01 || this._opcode === 0x02) {
|
|
if (this._fragmented) {
|
|
this._loop = false;
|
|
return error(RangeError, `invalid opcode ${this._opcode}`, true, 1002);
|
|
}
|
|
|
|
this._compressed = compressed;
|
|
} else if (this._opcode > 0x07 && this._opcode < 0x0b) {
|
|
if (!this._fin) {
|
|
this._loop = false;
|
|
return error(RangeError, 'FIN must be set', true, 1002);
|
|
}
|
|
|
|
if (compressed) {
|
|
this._loop = false;
|
|
return error(RangeError, 'RSV1 must be clear', true, 1002);
|
|
}
|
|
|
|
if (this._payloadLength > 0x7d) {
|
|
this._loop = false;
|
|
return error(
|
|
RangeError,
|
|
`invalid payload length ${this._payloadLength}`,
|
|
true,
|
|
1002
|
|
);
|
|
}
|
|
} else {
|
|
this._loop = false;
|
|
return error(RangeError, `invalid opcode ${this._opcode}`, true, 1002);
|
|
}
|
|
|
|
if (!this._fin && !this._fragmented) this._fragmented = this._opcode;
|
|
this._masked = (buf[1] & 0x80) === 0x80;
|
|
|
|
if (this._payloadLength === 126) this._state = GET_PAYLOAD_LENGTH_16;
|
|
else if (this._payloadLength === 127) this._state = GET_PAYLOAD_LENGTH_64;
|
|
else return this.haveLength();
|
|
}
|
|
|
|
/**
|
|
* Gets extended payload length (7+16).
|
|
*
|
|
* @return {(RangeError|undefined)} A possible error
|
|
* @private
|
|
*/
|
|
getPayloadLength16 () {
|
|
if (this._bufferedBytes < 2) {
|
|
this._loop = false;
|
|
return;
|
|
}
|
|
|
|
this._payloadLength = this.consume(2).readUInt16BE(0);
|
|
return this.haveLength();
|
|
}
|
|
|
|
/**
|
|
* Gets extended payload length (7+64).
|
|
*
|
|
* @return {(RangeError|undefined)} A possible error
|
|
* @private
|
|
*/
|
|
getPayloadLength64 () {
|
|
if (this._bufferedBytes < 8) {
|
|
this._loop = false;
|
|
return;
|
|
}
|
|
|
|
const buf = this.consume(8);
|
|
const num = buf.readUInt32BE(0);
|
|
|
|
//
|
|
// The maximum safe integer in JavaScript is 2^53 - 1. An error is returned
|
|
// if payload length is greater than this number.
|
|
//
|
|
if (num > Math.pow(2, 53 - 32) - 1) {
|
|
this._loop = false;
|
|
return error(
|
|
RangeError,
|
|
'Unsupported WebSocket frame: payload length > 2^53 - 1',
|
|
false,
|
|
1009
|
|
);
|
|
}
|
|
|
|
this._payloadLength = num * Math.pow(2, 32) + buf.readUInt32BE(4);
|
|
return this.haveLength();
|
|
}
|
|
|
|
/**
|
|
* Payload length has been read.
|
|
*
|
|
* @return {(RangeError|undefined)} A possible error
|
|
* @private
|
|
*/
|
|
haveLength () {
|
|
if (this._payloadLength && this._opcode < 0x08) {
|
|
this._totalPayloadLength += this._payloadLength;
|
|
if (this._totalPayloadLength > this._maxPayload && this._maxPayload > 0) {
|
|
this._loop = false;
|
|
return error(RangeError, 'Max payload size exceeded', false, 1009);
|
|
}
|
|
}
|
|
|
|
if (this._masked) this._state = GET_MASK;
|
|
else this._state = GET_DATA;
|
|
}
|
|
|
|
/**
|
|
* Reads mask bytes.
|
|
*
|
|
* @private
|
|
*/
|
|
getMask () {
|
|
if (this._bufferedBytes < 4) {
|
|
this._loop = false;
|
|
return;
|
|
}
|
|
|
|
this._mask = this.consume(4);
|
|
this._state = GET_DATA;
|
|
}
|
|
|
|
/**
|
|
* Reads data bytes.
|
|
*
|
|
* @param {Function} cb Callback
|
|
* @return {(Error|RangeError|undefined)} A possible error
|
|
* @private
|
|
*/
|
|
getData (cb) {
|
|
var data = constants.EMPTY_BUFFER;
|
|
|
|
if (this._payloadLength) {
|
|
if (this._bufferedBytes < this._payloadLength) {
|
|
this._loop = false;
|
|
return;
|
|
}
|
|
|
|
data = this.consume(this._payloadLength);
|
|
if (this._masked) bufferUtil.unmask(data, this._mask);
|
|
}
|
|
|
|
if (this._opcode > 0x07) return this.controlMessage(data);
|
|
|
|
if (this._compressed) {
|
|
this._state = INFLATING;
|
|
this.decompress(data, cb);
|
|
return;
|
|
}
|
|
|
|
if (data.length) {
|
|
//
|
|
// This message is not compressed so its lenght is the sum of the payload
|
|
// length of all fragments.
|
|
//
|
|
this._messageLength = this._totalPayloadLength;
|
|
this._fragments.push(data);
|
|
}
|
|
|
|
return this.dataMessage();
|
|
}
|
|
|
|
/**
|
|
* Decompresses data.
|
|
*
|
|
* @param {Buffer} data Compressed data
|
|
* @param {Function} cb Callback
|
|
* @private
|
|
*/
|
|
decompress (data, cb) {
|
|
const perMessageDeflate = this._extensions[PerMessageDeflate.extensionName];
|
|
|
|
perMessageDeflate.decompress(data, this._fin, (err, buf) => {
|
|
if (err) return cb(err);
|
|
|
|
if (buf.length) {
|
|
this._messageLength += buf.length;
|
|
if (this._messageLength > this._maxPayload && this._maxPayload > 0) {
|
|
return cb(error(RangeError, 'Max payload size exceeded', false, 1009));
|
|
}
|
|
|
|
this._fragments.push(buf);
|
|
}
|
|
|
|
const er = this.dataMessage();
|
|
if (er) return cb(er);
|
|
|
|
this.startLoop(cb);
|
|
});
|
|
}
|
|
|
|
/**
|
|
* Handles a data message.
|
|
*
|
|
* @return {(Error|undefined)} A possible error
|
|
* @private
|
|
*/
|
|
dataMessage () {
|
|
if (this._fin) {
|
|
const messageLength = this._messageLength;
|
|
const fragments = this._fragments;
|
|
|
|
this._totalPayloadLength = 0;
|
|
this._messageLength = 0;
|
|
this._fragmented = 0;
|
|
this._fragments = [];
|
|
|
|
if (this._opcode === 2) {
|
|
var data;
|
|
|
|
if (this._binaryType === 'nodebuffer') {
|
|
data = toBuffer(fragments, messageLength);
|
|
} else if (this._binaryType === 'arraybuffer') {
|
|
data = toArrayBuffer(toBuffer(fragments, messageLength));
|
|
} else {
|
|
data = fragments;
|
|
}
|
|
|
|
this.emit('message', data);
|
|
} else {
|
|
const buf = toBuffer(fragments, messageLength);
|
|
|
|
if (!validation.isValidUTF8(buf)) {
|
|
this._loop = false;
|
|
return error(Error, 'invalid UTF-8 sequence', true, 1007);
|
|
}
|
|
|
|
this.emit('message', buf.toString());
|
|
}
|
|
}
|
|
|
|
this._state = GET_INFO;
|
|
}
|
|
|
|
/**
|
|
* Handles a control message.
|
|
*
|
|
* @param {Buffer} data Data to handle
|
|
* @return {(Error|RangeError|undefined)} A possible error
|
|
* @private
|
|
*/
|
|
controlMessage (data) {
|
|
if (this._opcode === 0x08) {
|
|
this._loop = false;
|
|
|
|
if (data.length === 0) {
|
|
this.emit('conclude', 1005, '');
|
|
this.end();
|
|
} else if (data.length === 1) {
|
|
return error(RangeError, 'invalid payload length 1', true, 1002);
|
|
} else {
|
|
const code = data.readUInt16BE(0);
|
|
|
|
if (!validation.isValidStatusCode(code)) {
|
|
return error(RangeError, `invalid status code ${code}`, true, 1002);
|
|
}
|
|
|
|
const buf = data.slice(2);
|
|
|
|
if (!validation.isValidUTF8(buf)) {
|
|
return error(Error, 'invalid UTF-8 sequence', true, 1007);
|
|
}
|
|
|
|
this.emit('conclude', code, buf.toString());
|
|
this.end();
|
|
}
|
|
|
|
return;
|
|
}
|
|
|
|
if (this._opcode === 0x09) this.emit('ping', data);
|
|
else this.emit('pong', data);
|
|
|
|
this._state = GET_INFO;
|
|
}
|
|
}
|
|
|
|
module.exports = Receiver;
|
|
|
|
/**
|
|
* Builds an error object.
|
|
*
|
|
* @param {(Error|RangeError)} ErrorCtor The error constructor
|
|
* @param {String} message The error message
|
|
* @param {Boolean} prefix Specifies whether or not to add a default prefix to
|
|
* `message`
|
|
* @param {Number} statusCode The status code
|
|
* @return {(Error|RangeError)} The error
|
|
* @private
|
|
*/
|
|
function error (ErrorCtor, message, prefix, statusCode) {
|
|
const err = new ErrorCtor(
|
|
prefix ? `Invalid WebSocket frame: ${message}` : message
|
|
);
|
|
|
|
Error.captureStackTrace(err, error);
|
|
err[constants.kStatusCode] = statusCode;
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* Makes a buffer from a list of fragments.
|
|
*
|
|
* @param {Buffer[]} fragments The list of fragments composing the message
|
|
* @param {Number} messageLength The length of the message
|
|
* @return {Buffer}
|
|
* @private
|
|
*/
|
|
function toBuffer (fragments, messageLength) {
|
|
if (fragments.length === 1) return fragments[0];
|
|
if (fragments.length > 1) return bufferUtil.concat(fragments, messageLength);
|
|
return constants.EMPTY_BUFFER;
|
|
}
|
|
|
|
/**
|
|
* Converts a buffer to an `ArrayBuffer`.
|
|
*
|
|
* @param {Buffer} The buffer to convert
|
|
* @return {ArrayBuffer} Converted buffer
|
|
*/
|
|
function toArrayBuffer (buf) {
|
|
if (buf.byteOffset === 0 && buf.byteLength === buf.buffer.byteLength) {
|
|
return buf.buffer;
|
|
}
|
|
|
|
return buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength);
|
|
}
|