Bencode

Simple Bencode implementation in Rust.

What is it?

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.

bittorrent specs

Specs

• Strings are length-prefixed base ten followed by a colon and the string. For example 4:spam corresponds to 'spam'.
• Integers are represented by an 'i' followed by the number in base 10 followed by an 'e'. For example i3e corresponds to 3 and i-3e corresponds to -3. Integers have no size limitation. i-0e is invalid. All encodings with a leading zero, such as i03e, are invalid, other than i0e, which of course corresponds to 0.
• Lists are encoded as an 'l' followed by their elements (also bencoded) followed by an 'e'. For example l4:spam4:eggse corresponds to ['spam', 'eggs'].
• Dictionaries are encoded as a 'd' followed by a list of alternating keys and their corresponding values followed by an 'e'. For example, d3:cow3:moo4:spam4:eggse corresponds to {'cow': 'moo', 'spam': 'eggs'} and d4:spaml1:a1:bee corresponds to {'spam': ['a', 'b']}. Keys must be strings and appear in sorted order (sorted as raw strings, not alphanumerics).

Example

Given

d4:listl3:foo3:bare3:numi420ee

Then

{
    "list": [ "foo", "bar" ],
    "num": 420
}

TODO

• Add dictionary parsing
• Add object encoding
• Refine library interface

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Matias Alvin 2019