bencode

This project is part of the @thi.ng/umbrella monorepo.

• About
  • Features / behaviors
    • Booleans
    • String handling
    • Floating point values
  • Status
• Installation
• Dependencies
• API
• Authors
• License

About

Binary Bencode encoder & decoder for structured data.

Features / behaviors

Booleans

Will be converted to 0 or 1.

String handling

All JS strings will be UTF-8 encoded. To write raw bytes without transformation, wrap them as Uint8Array. These too will be written as Bencode strings (e.g. len:xxx...), but are used as is.

Floating point values

This implementation has optional (non-standard) support for floating point values. If these are not desired (e.g. for compatibility reasons), all numeric values MUST be pre-rounded to integers. The encoder only chooses the custom float encoding iff a number has a fractional part. Floats are encoded similarly to standard ints (i.e. as text), but using f as prefix. Furthermore, only floats with an absolute value in the semi-open [1e-6,1e21) interval can be encoded.

Status

STABLE - used in production

Search or submit any issues for this package

Installation

yarn add @thi.ng/bencode

ES module import:

<script type="module" src="https://cdn.skypack.dev/@thi.ng/bencode"></script>

Skypack documentation

For NodeJS (v14.6+):

node --experimental-specifier-resolution=node --experimental-repl-await

> const bencode = await import("@thi.ng/bencode");

Package sizes (gzipped, pre-treeshake): ESM: 1.23 KB

Dependencies

• @thi.ng/arrays
• @thi.ng/checks
• @thi.ng/defmulti
• @thi.ng/errors
• @thi.ng/transducers
• @thi.ng/transducers-binary

API

Generated API docs

import { encode, decode } from "@thi.ng/bencode";
import { hexDump } from "@thi.ng/transducers-binary";

[...hexDump({}, encode({ foo: "bar", "baz": [0, 1, 2, 3], "pi": Math.PI }))]
// [ '00000000 | 64 33 3a 62 61 7a 6c 69 30 65 69 31 65 69 32 65 | d3:bazli0ei1ei2e',
//   '00000010 | 69 33 65 65 33 3a 66 6f 6f 33 3a 62 61 72 32 3a | i3ee3:foo3:bar2:',
//   '00000020 | 70 69 66 33 2e 31 34 31 35 39 32 36 35 33 35 38 | pif3.14159265358',
//   '00000030 | 39 37 39 33 65 65 00 00 00 00 00 00 00 00 00 00 | 9793ee..........' ]

// Uin8Array values are written verbatim (as Bencode strings)
[...hexDump({}, encode({ foo: new Uint8Array([0, 1 ,2, 3]) }))]
// [ '00000000 | 64 33 3a 66 6f 6f 34 3a 00 01 02 03 65 00 00 00 | d3:foo4:....e...' ]

const bytes = encode({ foo: [1, "a", { bar: "baz"}, [42]] });
// Uint8Array [ 100, 51, 58, 102, 111, 111, 108, 105, 49, 101, 49, ... ]

decode(bytes)
// { foo: [ 1, 'a', { bar: 'baz' }, [ 42 ] ] }

// decode w/o UTF8 decoding
// (note: dictionary keys will ALWAYS be utf8 decoded)
decode(bytes, false)
// { foo: [ 1, [ 97 ], { bar: [ 98, 97, 122 ] }, [ 42 ] ] }

Authors

Karsten Schmidt

If this project contributes to an academic publication, please cite it as:

@misc{thing-bencode,
  title = "@thi.ng/bencode",
  author = "Karsten Schmidt",
  note = "https://thi.ng/bencode",
  year = 2016
}

License

© 2016 - 2021 Karsten Schmidt // Apache Software License 2.0