Package Exports

binary-data

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Readme

binary-data

Declarative binary data encoder / decoder. This module works almost like as binary or restructure but provided modern and clean api. It inspired by abstract-encoding interface.

Support

Usage

decode

const { decode, createDecode, types: { uint8, array, string } } = require('binary-data')

// 1. Define your own schema as plain object
const protocol = {
  type: uint8,
  value: array(string(null), uint8)
}

const message = Buffer.from([1, 2, 3, 4, 5, 6, 0]);

// Just decode message
const packet = decode(message, protocol)

// 2 Also you may decode messages from streams
const net = require('net');

const socket = net.createConnection({ port: 8124 });
const istream = createDecode(protocol);

socket.pipe(istream).on('data', packet => {
  console.log(packet.type, packet.value);
});

encode

const { encode, createEncode, types: { uint8, string } } = require('binary-data')

const protocol = {
  type: uint8,
  value: string(uint8)
}

const hello = {
  type: 12,
  value: 'my random data'
}

// Just encode message
const ostream = encode(hello, protocol);
const packet = ostream.slice();

// Or you may encode messages into a stream
const net = require('net');

const ostream = createEncode(protocol);
const socket = net.createConnection({ port: 8124 }, () => {
  ostream.write(hello);
});

ostream.pipe(socket);

// You may combine multiple schemes into one stream
const ostream = createEncode();

encode(obj1, ostream, protocol1);
encode(obj2, ostream, protocol2);
encode(obj3, ostream, protocol3);

const packet = ostream.slice();

See stun or dtls module for complete example.

Perfomance

Decoding DTLS ClientHello packet, nodejs 10.14.1 / Ubuntu 16.04 x64

name	time
binary data	637.900ms
binary	2229.218ms

API

encode(obj: any, [target: BinaryStream], type: Object): BinaryStream
decode(source: BinaryStream|Buffer, type: Object): any
encodingLength(item: any, type: Object): Number
createEncodeStream([type: Object]): BinaryStream
createDecodeStream([type: Object|Buffer]): BinaryStream
createEncode([type: Object]): BinaryStream
createDecode([type: Object|Buffer]): BinaryStream
Types

`decode(source: BinaryStream|Buffer, type: Object): any`

Reads any data from stream rstream using data type type. See examples above.

`encode(obj: any, [target: BinaryStream], type: Object): BinaryStream`

Writes any data obj to stream target using data type type. See examples above.

`encodingLength(item: any, type: Object): Number`

Return the amount of bytes needed to encode item using type.

`createEncodeStream([type: Object]): BinaryStream`

`createEncode([type: Object]): BinaryStream`

Create instance of BinaryStream.

`createDecodeStream([type: Object|Buffer]): BinaryStream`

`createDecode([type: Object|Buffer]): BinaryStream`

Create instance of BinaryStream.

`types: Object`

Contains all primitive data types.

Types

`(u)int(8, 16, 24, 32, 40, 48)(be, le)`

Low-level integer types.

const schema = {
  type: int8
}

// define int64 as buffer and use your loved library for big numbers
const int64 = buffer(8)

`(double, float)(be, le)`

Low-level floating-point types.

const schema = {
  size: doublele
}

`array(type: Object, length: number|Object|Function, lengthType: string)`

Array of low-level or user defined types. Argument type should be primitive type or user defined scheme. Argument length should be a number, number type or function. Argument lengthType should be bytes or count (default).

array(uint8, 3) // 3 x uint8

const schema = {
  length: uint8,
  type: uint32be,
  items: array(uint16, ({node}) => node.length, 'bytes')
}

// difference between `bytes` or `count`

array(uint16, uint8)
// |   0x2  | 0x0 0x1 | 0x0 0x2 |
// | length | item 1  |  item 2 |
// bytes = 1 + 4, length = 2

array(uint16, uint8, 'bytes')
// |   0x4  | 0x0 0x1 | 0x0 0x2 |
// | length | item 1  |  item 2 |
// bytes = 1 + 4, length = 4

`string(length)`

Low-level string type. Argument length can be number, null for C - strings, type for size-prefixed data or function.

`bool(type: any)`

Convert provided type to / from boolean. Argument type should be an number type.

const schema = bool(uint8)
const rstream = createDecodeStream(buf) // 0x01 0

decode(rstream, schema) // return true
decode(rstream, schema) // return false

`buffer(length: Object|null|number)`

Low-level buffer type. Argument length can be number, number type for size-prefixed data, function or null.

buffer(5) // buffer should be 5 bytes

buffer(uint8) // length prefixed buffer
// |   0x3  | 0xa 0xb 0xc
// | length | data

const packet = {
  header: {
    length: uint16be
  },
  data: buffer(({node}) => node.header.length % 2) // function should return actual length
}

`reserved(type, count)`

Special type to skip any data. Argument count should be a number, number type or function.

const packet = {
  type: uint8,
  _padding: reserved(uint8, 3)
}

decode(rstream, packet) // return { type }

`when(fn: function(context): boolean, type)`

Special type for conditions. Argument fn should be a function and should return boolean value. The type argument will be evaluated when the first one returns positive value.

const schema = {
  type: uint8,
  bytes: when(({ node }) => node.type === 1, string(uint16be)),
  list: when(({ node }) => node.type === 2, array(uint32be, uint8))
}

`select(when, ..., defaultType)`

The second type for conditions. The same as switch operator in js. Argument defaultType may be any known type excluding user schemas.

const schema = {
  id: uint8,
  payload: select(when(({ node }) => node.id === 1, string(uint16be)), buffer(uint16be))
}

License

MIT, 2017 (c) Dmitriy Tsvettsikh