npm install bencodingA node library for encoding and decoding data, according to the
BitTorrent specification.
This library is slightly different, because it attempts to keep your
data as pristine as possible. Nothing (with the exception of integers)
is converted to a string until you tell it to.
There are a bunch of bencoding/decoding libraries out there (see below),
but none of pass their results straight into plain javascript Objects
({}). When using a Buffer as a key in an Object, it automatically
gets coerced into a String. If you have to use some complex data as a
key in a dictionary, it'll munge it when converting it to a String.
Take for example a scrape request to a HTTP tracker. According to the
unofficial BT spec,
its result is in this format (written in JS-pseudocode for clarity):
``javascript`
{
"files": {
"[info hash]": {
"complete": 5,
"downloaded": 50,
"incomplete": 10
}
}
}
Where [info hash] is the 20-byte sha1 info_hash. When you coerceString
this into a string, you get some wonky effects, such as the (20-byte)'s length being 1. This is not all so helpful, unless you'reinfo_hash
completely willing disregard the .
bencoding fixes this by creating a new structure: BDict. A BDict
represents a bencoded dictionary without coercing any s intoStrings. It stores everything by index, so you have to fetch the keys
and values numerically (see API).
With npm:
npm install bencoding
Performance compared to:
* Mark Schmale's bencode
* Tim Becker's bncode
* Stefan Bühler's dht-bencode
This library seems to __decode__ faster than any of the other tested
libraries. It __encodes__ quickly – second only to Mark Schmale's
library. Results:
> Encoding:
>
> * bencoding#encode x 24,961 ops/sec ±4.12% (57 runs sampled)
> * bencode#encode x 2,637,008 ops/sec ±5.86% (58 runs sampled)
> * bncode#encode x 15,012 ops/sec ±7.66% (46 runs sampled)
> * dht-bencode#encode x 193,631 ops/sec ±10.35% (53 runs sampled)
> * Fastest is bencode#encode
>
> Decoding:
>
> * bencoding#decode x 29,019 ops/sec ±4.41% (55 runs sampled)
> * bencode#decode x 300 ops/sec ±6.28% (54 runs sampled)
> * bncode#decode x 1,060 ops/sec ±7.65% (50 runs sampled)
> * [dht-decode errors]
> * Fastest is bencoding#decode
You can try this yourself by running either node
performance/encoding.js or node performance/decoding.js.
javascript
var bencoding = require('bencoding'),
data = new Buffer('d3:inti1024768e3:str5:abcde4:listli1ei2ei3eee'),
result = bencoding.decode(data);console.log(result);
console.log(result.toJSON());
`
Output:
{ keys: [ , , ],
vals: [ 1024768, , [ 1, 2, 3 ] ],
length: 3 }
{ int: 1024768, str: , list: [ 1, 2, 3 ] }
$3
javascript
var bencoding = require('bencoding'),
object = {
'string': "Hello World",
'integer': 12345,
'dictionary': {
'key': "This is a string within a dictionary"
},
'list': [1, 2, 3, 4, 'string', 5, {}]
},
result = bencoding.encode(object);console.log(result.toString());
`
Output: d6:string11:Hello World7:integeri12345e10:dictionaryd3:key36:This is a string within a dictionarye4:listli1ei2ei3ei4e6:stringi5edeee
API
$3
Signature: * {
} encoded - The bencoded data, as a buffer.Returns {
Buffer|BDict|Array|Number} result - decoded data$3
Signature:* {
Buffer|BDict|Array|String|Object|Number} data - the
data to encode.Returns {
Buffer} result - encoded data. $3
The BDict constructor. Accepts no arguments.#### BDict.add
Signature:
*
key - the key
* value - the valueReturns: {
BDict} self - for chainingAdds an item to
BDict at length. key and value can be any object
of any kind.#### BDict.remove
Signature:
* {
Number} index - the index to removeReturns: {
BDict} self - for chainingRemoves item at index
index from BDict#### BDict.vget
Signature:
* {
} index - the index to get the value ofReturns:
value - the value at index index.#### BDict.kget
Signature:
* {
Number} index - the index to get the key ofReturns:
value - the key at index index.#### BDict.get
Signature:
* {
Number} index - the index to get the key/value ofReturns: {
Array} result - an array in the format of [key, value]#### BDict.toJSON
Returns: {
Object} result - a usable representation of the BDict.If you don't plan on having any complex data in keys, you can just call
toJSON to convert the BDict into a regular
Object`.(The MIT License)
Copyright (c) 2011 Clark Fischer <clark.fischer@gmail.com>
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.