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sender.js
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Tue, Feb 4, 18:43

sender.js
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/* eslint no-unused-vars: ["error", { "varsIgnorePattern": "^net|tls$" }] */
'use strict';
const net = require('net');
const tls = require('tls');
const { randomFillSync } = require('crypto');
const PerMessageDeflate = require('./permessage-deflate');
const { EMPTY_BUFFER } = require('./constants');
const { isValidStatusCode } = require('./validation');
const { mask: applyMask, toBuffer } = require('./buffer-util');
const kByteLength = Symbol('kByteLength');
const maskBuffer = Buffer.alloc(4);
/**
* HyBi Sender implementation.
*/
class Sender {
/**
* Creates a Sender instance.
*
* @param {(net.Socket|tls.Socket)} socket The connection socket
* @param {Object} [extensions] An object containing the negotiated extensions
* @param {Function} [generateMask] The function used to generate the masking
* key
*/
constructor(socket, extensions, generateMask) {
this._extensions = extensions || {};
if (generateMask) {
this._generateMask = generateMask;
this._maskBuffer = Buffer.alloc(4);
}
this._socket = socket;
this._firstFragment = true;
this._compress = false;
this._bufferedBytes = 0;
this._deflating = false;
this._queue = [];
}
/**
* Frames a piece of data according to the HyBi WebSocket protocol.
*
* @param {(Buffer|String)} data The data to frame
* @param {Object} options Options object
* @param {Boolean} [options.fin=false] Specifies whether or not to set the
* FIN bit
* @param {Function} [options.generateMask] The function used to generate the
* masking key
* @param {Boolean} [options.mask=false] Specifies whether or not to mask
* `data`
* @param {Buffer} [options.maskBuffer] The buffer used to store the masking
* key
* @param {Number} options.opcode The opcode
* @param {Boolean} [options.readOnly=false] Specifies whether `data` can be
* modified
* @param {Boolean} [options.rsv1=false] Specifies whether or not to set the
* RSV1 bit
* @return {(Buffer|String)[]} The framed data
* @public
*/
static frame(data, options) {
let mask;
let merge = false;
let offset = 2;
let skipMasking = false;
if (options.mask) {
mask = options.maskBuffer || maskBuffer;
if (options.generateMask) {
options.generateMask(mask);
} else {
randomFillSync(mask, 0, 4);
}
skipMasking = (mask[0] | mask[1] | mask[2] | mask[3]) === 0;
offset = 6;
}
let dataLength;
if (typeof data === 'string') {
if (
(!options.mask || skipMasking) &&
options[kByteLength] !== undefined
) {
dataLength = options[kByteLength];
} else {
data = Buffer.from(data);
dataLength = data.length;
}
} else {
dataLength = data.length;
merge = options.mask && options.readOnly && !skipMasking;
}
let payloadLength = dataLength;
if (dataLength >= 65536) {
offset += 8;
payloadLength = 127;
} else if (dataLength > 125) {
offset += 2;
payloadLength = 126;
}
const target = Buffer.allocUnsafe(merge ? dataLength + offset : offset);
target[0] = options.fin ? options.opcode | 0x80 : options.opcode;
if (options.rsv1) target[0] |= 0x40;
target[1] = payloadLength;
if (payloadLength === 126) {
target.writeUInt16BE(dataLength, 2);
} else if (payloadLength === 127) {
target[2] = target[3] = 0;
target.writeUIntBE(dataLength, 4, 6);
}
if (!options.mask) return [target, data];
target[1] |= 0x80;
target[offset - 4] = mask[0];
target[offset - 3] = mask[1];
target[offset - 2] = mask[2];
target[offset - 1] = mask[3];
if (skipMasking) return [target, data];
if (merge) {
applyMask(data, mask, target, offset, dataLength);
return [target];
}
applyMask(data, mask, data, 0, dataLength);
return [target, data];
}
/**
* Sends a close message to the other peer.
*
* @param {Number} [code] The status code component of the body
* @param {(String|Buffer)} [data] The message component of the body
* @param {Boolean} [mask=false] Specifies whether or not to mask the message
* @param {Function} [cb] Callback
* @public
*/
close(code, data, mask, cb) {
let buf;
if (code === undefined) {
buf = EMPTY_BUFFER;
} else if (typeof code !== 'number' || !isValidStatusCode(code)) {
throw new TypeError('First argument must be a valid error code number');
} else if (data === undefined || !data.length) {
buf = Buffer.allocUnsafe(2);
buf.writeUInt16BE(code, 0);
} else {
const length = Buffer.byteLength(data);
if (length > 123) {
throw new RangeError('The message must not be greater than 123 bytes');
}
buf = Buffer.allocUnsafe(2 + length);
buf.writeUInt16BE(code, 0);
if (typeof data === 'string') {
buf.write(data, 2);
} else {
buf.set(data, 2);
}
}
const options = {
[kByteLength]: buf.length,
fin: true,
generateMask: this._generateMask,
mask,
maskBuffer: this._maskBuffer,
opcode: 0x08,
readOnly: false,
rsv1: false
};
if (this._deflating) {
this.enqueue([this.dispatch, buf, false, options, cb]);
} else {
this.sendFrame(Sender.frame(buf, options), cb);
}
}
/**
* Sends a ping message to the other peer.
*
* @param {*} data The message to send
* @param {Boolean} [mask=false] Specifies whether or not to mask `data`
* @param {Function} [cb] Callback
* @public
*/
ping(data, mask, cb) {
let byteLength;
let readOnly;
if (typeof data === 'string') {
byteLength = Buffer.byteLength(data);
readOnly = false;
} else {
data = toBuffer(data);
byteLength = data.length;
readOnly = toBuffer.readOnly;
}
if (byteLength > 125) {
throw new RangeError('The data size must not be greater than 125 bytes');
}
const options = {
[kByteLength]: byteLength,
fin: true,
generateMask: this._generateMask,
mask,
maskBuffer: this._maskBuffer,
opcode: 0x09,
readOnly,
rsv1: false
};
if (this._deflating) {
this.enqueue([this.dispatch, data, false, options, cb]);
} else {
this.sendFrame(Sender.frame(data, options), cb);
}
}
/**
* Sends a pong message to the other peer.
*
* @param {*} data The message to send
* @param {Boolean} [mask=false] Specifies whether or not to mask `data`
* @param {Function} [cb] Callback
* @public
*/
pong(data, mask, cb) {
let byteLength;
let readOnly;
if (typeof data === 'string') {
byteLength = Buffer.byteLength(data);
readOnly = false;
} else {
data = toBuffer(data);
byteLength = data.length;
readOnly = toBuffer.readOnly;
}
if (byteLength > 125) {
throw new RangeError('The data size must not be greater than 125 bytes');
}
const options = {
[kByteLength]: byteLength,
fin: true,
generateMask: this._generateMask,
mask,
maskBuffer: this._maskBuffer,
opcode: 0x0a,
readOnly,
rsv1: false
};
if (this._deflating) {
this.enqueue([this.dispatch, data, false, options, cb]);
} else {
this.sendFrame(Sender.frame(data, options), cb);
}
}
/**
* Sends a data message to the other peer.
*
* @param {*} data The message to send
* @param {Object} options Options object
* @param {Boolean} [options.binary=false] Specifies whether `data` is binary
* or text
* @param {Boolean} [options.compress=false] Specifies whether or not to
* compress `data`
* @param {Boolean} [options.fin=false] Specifies whether the fragment is the
* last one
* @param {Boolean} [options.mask=false] Specifies whether or not to mask
* `data`
* @param {Function} [cb] Callback
* @public
*/
send(data, options, cb) {
const perMessageDeflate = this._extensions[PerMessageDeflate.extensionName];
let opcode = options.binary ? 2 : 1;
let rsv1 = options.compress;
let byteLength;
let readOnly;
if (typeof data === 'string') {
byteLength = Buffer.byteLength(data);
readOnly = false;
} else {
data = toBuffer(data);
byteLength = data.length;
readOnly = toBuffer.readOnly;
}
if (this._firstFragment) {
this._firstFragment = false;
if (
rsv1 &&
perMessageDeflate &&
perMessageDeflate.params[
perMessageDeflate._isServer
? 'server_no_context_takeover'
: 'client_no_context_takeover'
]
) {
rsv1 = byteLength >= perMessageDeflate._threshold;
}
this._compress = rsv1;
} else {
rsv1 = false;
opcode = 0;
}
if (options.fin) this._firstFragment = true;
if (perMessageDeflate) {
const opts = {
[kByteLength]: byteLength,
fin: options.fin,
generateMask: this._generateMask,
mask: options.mask,
maskBuffer: this._maskBuffer,
opcode,
readOnly,
rsv1
};
if (this._deflating) {
this.enqueue([this.dispatch, data, this._compress, opts, cb]);
} else {
this.dispatch(data, this._compress, opts, cb);
}
} else {
this.sendFrame(
Sender.frame(data, {
[kByteLength]: byteLength,
fin: options.fin,
generateMask: this._generateMask,
mask: options.mask,
maskBuffer: this._maskBuffer,
opcode,
readOnly,
rsv1: false
}),
cb
);
}
}
/**
* Dispatches a message.
*
* @param {(Buffer|String)} data The message to send
* @param {Boolean} [compress=false] Specifies whether or not to compress
* `data`
* @param {Object} options Options object
* @param {Boolean} [options.fin=false] Specifies whether or not to set the
* FIN bit
* @param {Function} [options.generateMask] The function used to generate the
* masking key
* @param {Boolean} [options.mask=false] Specifies whether or not to mask
* `data`
* @param {Buffer} [options.maskBuffer] The buffer used to store the masking
* key
* @param {Number} options.opcode The opcode
* @param {Boolean} [options.readOnly=false] Specifies whether `data` can be
* modified
* @param {Boolean} [options.rsv1=false] Specifies whether or not to set the
* RSV1 bit
* @param {Function} [cb] Callback
* @private
*/
dispatch(data, compress, options, cb) {
if (!compress) {
this.sendFrame(Sender.frame(data, options), cb);
return;
}
const perMessageDeflate = this._extensions[PerMessageDeflate.extensionName];
this._bufferedBytes += options[kByteLength];
this._deflating = true;
perMessageDeflate.compress(data, options.fin, (_, buf) => {
if (this._socket.destroyed) {
const err = new Error(
'The socket was closed while data was being compressed'
);
if (typeof cb === 'function') cb(err);
for (let i = 0; i < this._queue.length; i++) {
const params = this._queue[i];
const callback = params[params.length - 1];
if (typeof callback === 'function') callback(err);
}
return;
}
this._bufferedBytes -= options[kByteLength];
this._deflating = false;
options.readOnly = false;
this.sendFrame(Sender.frame(buf, options), cb);
this.dequeue();
});
}
/**
* Executes queued send operations.
*
* @private
*/
dequeue() {
while (!this._deflating && this._queue.length) {
const params = this._queue.shift();
this._bufferedBytes -= params[3][kByteLength];
Reflect.apply(params[0], this, params.slice(1));
}
}
/**
* Enqueues a send operation.
*
* @param {Array} params Send operation parameters.
* @private
*/
enqueue(params) {
this._bufferedBytes += params[3][kByteLength];
this._queue.push(params);
}
/**
* Sends a frame.
*
* @param {Buffer[]} list The frame to send
* @param {Function} [cb] Callback
* @private
*/
sendFrame(list, cb) {
if (list.length === 2) {
this._socket.cork();
this._socket.write(list[0]);
this._socket.write(list[1], cb);
this._socket.uncork();
} else {
this._socket.write(list[0], cb);
}
}
}
module.exports = Sender;

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