/**
* Module dependencies.
*/
var utf8 = require('wtf-8');
var after = require('after');
var keys = require('./keys');
/**
* Current protocol version.
*/
exports.protocol = 3;
/**
* Packet types.
*/
var packets = exports.packets = {
open: 0 // non-ws
, close: 1 // non-ws
, ping: 2
, pong: 3
, message: 4
, upgrade: 5
, noop: 6
};
var packetslist = keys(packets);
/**
* Premade error packet.
*/
var err = { type: 'error', data: 'parser error' };
/**
* Encodes a packet.
*
* <packet type id> [ <data> ]
*
* Example:
*
* 5hello world
* 3
* 4
*
* Binary is encoded in an identical principle
*
* @api private
*/
exports.encodePacket = function (packet, supportsBinary, utf8encode, callback) {
if ('function' == typeof supportsBinary) {
callback = supportsBinary;
supportsBinary = null;
}
if ('function' == typeof utf8encode ) {
callback = utf8encode;
utf8encode = null;
}
if (Buffer.isBuffer(packet.data)) {
return encodeBuffer(packet, supportsBinary, callback);
} else if (packet.data && (packet.data.buffer || packet.data) instanceof ArrayBuffer) {
packet.data = arrayBufferToBuffer(packet.data);
return encodeBuffer(packet, supportsBinary, callback);
}
// Sending data as a utf-8 string
var encoded = packets[packet.type];
// data fragment is optional
if (undefined !== packet.data) {
encoded += utf8encode ? utf8.encode(String(packet.data)) : String(packet.data);
}
return callback('' + encoded);
};
/**
* Encode Buffer data
*/
function encodeBuffer(packet, supportsBinary, callback) {
var data = packet.data;
if (!supportsBinary) {
return exports.encodeBase64Packet(packet, callback);
}
var typeBuffer = new Buffer(1);
typeBuffer[0] = packets[packet.type];
return callback(Buffer.concat([typeBuffer, data]));
}
/**
* Encodes a packet with binary data in a base64 string
*
* @param {Object} packet, has `type` and `data`
* @return {String} base64 encoded message
*/
exports.encodeBase64Packet = function(packet, callback){
if (!Buffer.isBuffer(packet.data)) {
packet.data = arrayBufferToBuffer(packet.data);
}
var message = 'b' + packets[packet.type];
message += packet.data.toString('base64');
return callback(message);
};
/**
* Decodes a packet. Data also available as an ArrayBuffer if requested.
*
* @return {Object} with `type` and `data` (if any)
* @api private
*/
exports.decodePacket = function (data, binaryType, utf8decode) {
if (data === undefined) {
return err;
}
// String data
if (typeof data == 'string') {
if (data.charAt(0) == 'b') {
return exports.decodeBase64Packet(data.substr(1), binaryType);
}
var type = data.charAt(0);
if (utf8decode) {
data = tryDecode(data);
if (data === false) {
return err;
}
}
if (Number(type) != type || !packetslist[type]) {
return err;
}
if (data.length > 1) {
return { type: packetslist[type], data: data.substring(1) };
} else {
return { type: packetslist[type] };
}
}
// Binary data
if (binaryType === 'arraybuffer') {
// wrap Buffer/ArrayBuffer data into an Uint8Array
var intArray = new Uint8Array(data);
var type = intArray[0];
return { type: packetslist[type], data: intArray.buffer.slice(1) };
}
if (data instanceof ArrayBuffer) {
data = arrayBufferToBuffer(data);
}
var type = data[0];
return { type: packetslist[type], data: data.slice(1) };
};
function tryDecode(data) {
try {
data = utf8.decode(data);
} catch (e) {
return false;
}
return data;
}
/**
* Decodes a packet encoded in a base64 string.
*
* @param {String} base64 encoded message
* @return {Object} with `type` and `data` (if any)
*/
exports.decodeBase64Packet = function(msg, binaryType) {
var type = packetslist[msg.charAt(0)];
var data = new Buffer(msg.substr(1), 'base64');
if (binaryType === 'arraybuffer') {
var abv = new Uint8Array(data.length);
for (var i = 0; i < abv.length; i++){
abv[i] = data[i];
}
data = abv.buffer;
}
return { type: type, data: data };
};
/**
* Encodes multiple messages (payload).
*
* <length>:data
*
* Example:
*
* 11:hello world2:hi
*
* If any contents are binary, they will be encoded as base64 strings. Base64
* encoded strings are marked with a b before the length specifier
*
* @param {Array} packets
* @api private
*/
exports.encodePayload = function (packets, supportsBinary, callback) {
if (typeof supportsBinary == 'function') {
callback = supportsBinary;
supportsBinary = null;
}
if (supportsBinary) {
return exports.encodePayloadAsBinary(packets, callback);
}
if (!packets.length) {
return callback('0:');
}
function setLengthHeader(message) {
return message.length + ':' + message;
}
function encodeOne(packet, doneCallback) {
exports.encodePacket(packet, supportsBinary, true, function(message) {
doneCallback(null, setLengthHeader(message));
});
}
map(packets, encodeOne, function(err, results) {
return callback(results.join(''));
});
};
/**
* Async array map using after
*/
function map(ary, each, done) {
var result = new Array(ary.length);
var next = after(ary.length, done);
var eachWithIndex = function(i, el, cb) {
each(el, function(error, msg) {
result[i] = msg;
cb(error, result);
});
};
for (var i = 0; i < ary.length; i++) {
eachWithIndex(i, ary[i], next);
}
}
/*
* Decodes data when a payload is maybe expected. Possible binary contents are
* decoded from their base64 representation
*
* @param {String} data, callback method
* @api public
*/
exports.decodePayload = function (data, binaryType, callback) {
if ('string' != typeof data) {
return exports.decodePayloadAsBinary(data, binaryType, callback);
}
if (typeof binaryType === 'function') {
callback = binaryType;
binaryType = null;
}
var packet;
if (data == '') {
// parser error - ignoring payload
return callback(err, 0, 1);
}
var length = ''
, n, msg;
for (var i = 0, l = data.length; i < l; i++) {
var chr = data.charAt(i);
if (':' != chr) {
length += chr;
} else {
if ('' == length || (length != (n = Number(length)))) {
// parser error - ignoring payload
return callback(err, 0, 1);
}
msg = data.substr(i + 1, n);
if (length != msg.length) {
// parser error - ignoring payload
return callback(err, 0, 1);
}
if (msg.length) {
packet = exports.decodePacket(msg, binaryType, true);
if (err.type == packet.type && err.data == packet.data) {
// parser error in individual packet - ignoring payload
return callback(err, 0, 1);
}
var ret = callback(packet, i + n, l);
if (false === ret) return;
}
// advance cursor
i += n;
length = '';
}
}
if (length != '') {
// parser error - ignoring payload
return callback(err, 0, 1);
}
};
/**
*
* Converts a buffer to a utf8.js encoded string
*
* @api private
*/
function bufferToString(buffer) {
var str = '';
for (var i = 0; i < buffer.length; i++) {
str += String.fromCharCode(buffer[i]);
}
return str;
}
/**
*
* Converts a utf8.js encoded string to a buffer
*
* @api private
*/
function stringToBuffer(string) {
var buf = new Buffer(string.length);
for (var i = 0; i < string.length; i++) {
buf.writeUInt8(string.charCodeAt(i), i);
}
return buf;
}
/**
*
* Converts an ArrayBuffer to a Buffer
*
* @api private
*/
function arrayBufferToBuffer(data) {
// data is either an ArrayBuffer or ArrayBufferView.
var array = new Uint8Array(data.buffer || data);
var length = data.byteLength || data.length;
var offset = data.byteOffset || 0;
var buffer = new Buffer(length);
for (var i = 0; i < length; i++) {
buffer[i] = array[offset + i];
}
return buffer;
}
/**
* Encodes multiple messages (payload) as binary.
*
* <1 = binary, 0 = string><number from 0-9><number from 0-9>[...]<number
* 255><data>
*
* Example:
* 1 3 255 1 2 3, if the binary contents are interpreted as 8 bit integers
*
* @param {Array} packets
* @return {Buffer} encoded payload
* @api private
*/
exports.encodePayloadAsBinary = function (packets, callback) {
if (!packets.length) {
return callback(new Buffer(0));
}
function encodeOne(p, doneCallback) {
exports.encodePacket(p, true, true, function(packet) {
if (typeof packet === 'string') {
var encodingLength = '' + packet.length;
var sizeBuffer = new Buffer(encodingLength.length + 2);
sizeBuffer[0] = 0; // is a string (not true binary = 0)
for (var i = 0; i < encodingLength.length; i++) {
sizeBuffer[i + 1] = parseInt(encodingLength[i], 10);
}
sizeBuffer[sizeBuffer.length - 1] = 255;
return doneCallback(null, Buffer.concat([sizeBuffer, stringToBuffer(packet)]));
}
var encodingLength = '' + packet.length;
var sizeBuffer = new Buffer(encodingLength.length + 2);
sizeBuffer[0] = 1; // is binary (true binary = 1)
for (var i = 0; i < encodingLength.length; i++) {
sizeBuffer[i + 1] = parseInt(encodingLength[i], 10);
}
sizeBuffer[sizeBuffer.length - 1] = 255;
doneCallback(null, Buffer.concat([sizeBuffer, packet]));
});
}
map(packets, encodeOne, function(err, results) {
return callback(Buffer.concat(results));
});
};
/*
* Decodes data when a payload is maybe expected. Strings are decoded by
* interpreting each byte as a key code for entries marked to start with 0. See
* description of encodePayloadAsBinary
* @param {Buffer} data, callback method
* @api public
*/
exports.decodePayloadAsBinary = function (data, binaryType, callback) {
if (typeof binaryType === 'function') {
callback = binaryType;
binaryType = null;
}
var bufferTail = data;
var buffers = [];
while (bufferTail.length > 0) {
var strLen = '';
var isString = bufferTail[0] === 0;
var numberTooLong = false;
for (var i = 1; ; i++) {
if (bufferTail[i] == 255) break;
// 310 = char length of Number.MAX_VALUE
if (strLen.length > 310) {
numberTooLong = true;
break;
}
strLen += '' + bufferTail[i];
}
if(numberTooLong) return callback(err, 0, 1);
bufferTail = bufferTail.slice(strLen.length + 1);
var msgLength = parseInt(strLen, 10);
var msg = bufferTail.slice(1, msgLength + 1);
if (isString) msg = bufferToString(msg);
buffers.push(msg);
bufferTail = bufferTail.slice(msgLength + 1);
}
var total = buffers.length;
buffers.forEach(function(buffer, i) {
callback(exports.decodePacket(buffer, binaryType, true), i, total);
});
};