packed

Binary Buffer parsing and packing that feels a little like C structs

Installation

npm install packed

Usage

var packed = require('packed');

// Create structure - from http://en.wikipedia.org/wiki/Transmission_Control_Protocol
var TcpHeaderStruct = packed({
  source_port: packed.uint16n,
  dest_port: packed.uint16n,
  sequence_number: packed.uint32n,
  ack_number: packed.uint32n,
  data_offset: packed.bits(4),
  reserved: packed.bits(3),
  control: {
    NS: packed.bits(1),
    CWR: packed.bits(1),
    ECE: packed.bits(1),
    URG: packed.bits(1),
    ACK: packed.bits(1),
    PSH: packed.bits(1),
    RST: packed.bits(1),
    SYN: packed.bits(1),
    FIN: packed.bits(1)
  },
  window_size: packed.uint16n,
  checksum: packed.uint16n,
  urgent_pointer: packed.uint16n
});

var original = {
  source_port: 13076,
  dest_port: 44112,
  sequence_number: 3322114,
  ack_number: 3322113,
  data_offset: 0x7,
  // reserved: -- auto-filled with zeros
  control: {
    NS: 0,
    CWR: 1,
    ECE: 0,
    URG: 0,
    ACK: 1,
    PSH: 0,
    RST: 0,
    SYN: 1,
    FIN: 0
  },
  window_size: 4096,
  checksum: 33412,
  urgent_pointer: 0
};

// Pack data into a buffer that you can send ... anywhere
var buffer = TcpHeaderStruct.pack(original);
// Unpack the buffer back into an object
var data = TcpHeaderStruct.unpack(buffer);

assert.deepEqual(data, original);

Methods

packed(structure_object)

Create a packed instance

Properties

packed.default_byte_order (defaults as 'BE')

Default byte order for field helpers without a suffix. Either 'BE', 'LE', or 'N' for big-endian, little-endian, or network.

Instance Methods

struct.pack(object)

Pack an object into a Buffer

struct.unpack(buffer)

Unpack a buffer into the struct

Structure Field Helpers

Signed Integers

packed.int8

8-bit integer (default byte order)

packed.int16

16-bit integer (default byte order)

packed.int16be

16-bit integer big-endian

packed.int16le

16-bit integer little-endian

packed.int16n

16-bit integer network order

packed.int32

32-bit integer (default byte order)

packed.int32be

32-bit integer big-endian

packed.int32le

32-bit integer little-endian

packed.int32n

32-bit integer network order

packed.int64

64-bit integer (default byte order)

packed.int64be

64-bit integer big-endian

packed.int64le

64-bit integer little-endian

packed.int64n

64-bit integer network order

Unsigned Integers

packed.uint8

8-bit unsigned integer (default byte order)

packed.uint16

16-bit unsigned integer (default byte order)

packed.uint16be

16-bit unsigned integer big-endian

packed.uint16le

16-bit unsigned integer little-endian

packed.uint16n

16-bit unsigned integer network order

packed.uint32

32-bit unsigned integer (default byte order)

packed.uint32be

32-bit unsigned integer big-endian

packed.uint32le

32-bit unsigned integer little-endian

packed.uint32n

32-bit unsigned integer network order

packed.uint64

64-bit unsigned integer (default byte order)

packed.uint64be

64-bit unsigned integer big-endian

packed.uint64le

64-bit unsigned integer little-endian

packed.uint64n

64-bit unsigned integer network order

Other

packed.string

Zero terminated String

packed.bits(number_of_bits)

Unsigned bits of variable length

mattinsler/packed