Bencode

A node library for encoding and decoding bencoded data, according to the BitTorrent specification.

Index

• About BEncoding
• Installation
• Performance
• Usage
• API

About BEncoding

from Wikipedia:

Bencode (pronounced like B encode) is the encoding used by the peer-to-peer file sharing system BitTorrent for storing and transmitting loosely structured data.

It supports four different types of values:

• byte strings
• integers
• lists
• dictionaries

Bencoding is most commonly used in torrent files. These metadata files are simply bencoded dictionaries.

Install with npm

npm install bencode

Performance

encode

19,235 op/s » bencode
 9,684 op/s » bencoding
11,988 op/s » dht_bencode
 8,946 op/s » bncode
18,744 op/s » dht

decode

33,786 op/s » bencode
55,040 op/s » bencoding
40,872 op/s » dht_bencode
 2,533 op/s » bncode
30,292 op/s » dht

Benchmarks run on an 1.8 GHz Intel Core i5 with io.js 1.0.4

To run the benchmarks simply use

npm run bench

Usage

var bencode = require( 'bencode' )

You can also use node-bencode with browserify to be able to use it in a lot of modern browsers.

Encoding

var data = {
  string: 'Hello World',
  integer: 12345,
  dict: {
    key: 'This is a string within a dictionary'
  },
  list: [ 1, 2, 3, 4, 'string', 5, {} ]
}

var result = bencode.encode( data )

Output

d4:dictd3:key36:This is a string within a dictionarye7:integeri12345e4:listli1ei2ei3ei4e6:stringi5edee6:string11:Hello Worlde

Decoding

var data   = new Buffer( 'd6:string11:Hello World7:integeri12345e4:dictd3:key36:This is a string within a dictionarye4:litli1ei2ei3ei4e6:stringi5edeee' )
var result = bencode.decode( data )

Output

{
  string: <Buffer 48 65 6c 6c 6f 20 57 6f 72 6c 64>,
  integer: 12345,
  dict: {
    key: <Buffer 54 68 69 73 20 69 73 20 61 20 73 74 72 69 6e 67 20 77 69 74 68 69 6e 20 61 20 64 69 63 74 69 6f 6e 61 72 79>
  },
  list: [ 1, 2, 3, 4, <Buffer 73 74 72 69 6e 67>, 5, {} ]
}

Automagically convert bytestrings to strings:

var result = bencode.decode( data, 'utf8' )

Output

{
  string: 'Hello World',
  integer: 12345,
  dict: {
    key: 'This is a string within a dictionary'
  },
  list: [ 1, 2, 3, 4, 'string', 5, {} ]
}

API

bencode.encode( data )

Buffer | Array | String | Object | Number data

Returns Buffer

bencode.decode( data, encoding )

Buffer data String encoding

If encoding is set, bytestrings are automatically converted to strings.

Returns Object | Array | Buffer | String | Number

Upcoming

• decode() now throws if it encounters invalid input

0.4.3

• improved performance a lot

• dropped support for de- and encoding floats to respect the spec

  note: node-bencode will still decodes stuff like "i42.23e" but will cast the result to an interger

0.4.2

• bugfix: sort dictionary keys to follow the spec

0.4.1

• bugfix: number decoding was kinda broken

0.4.0

• fixed problems with multibyte strings
• some performance improvements
• improved code quality

0.3.0

• decode() accepts a encoding as its second paramtere

0.2.0

• complete rewrite, @jhermsmeier joins the team

0.1.0

• added encoding

0.0.1

First version, decoding only