Bencoding

Bencoding is a bencoding library written in Elixir as part of developing an elixir BitTorrent.

This is a learning project and should not be used for anyone that expects quality in downloading or serving content over the BitTorrent protocol.

Installation

Simply add the bencoding entry to your mix.exs file:

def deps do
  [
    {:bencoding, git: "https://github.com/wilkmaia/bencoding.git", tag: "v0.1.1"}
  ]
end

Check available releases on the releases page.

Usage

Decoding Bencoding Strings

The Bencoding.decode/1 function is responsible for decoding bencoding-encoded data into elixir data. Successfull decodings return a tuple with an :ok atom and the decoded data

iex> Bencoding.decode("i3e")
{:ok, 3}
iex> Bencoding.decode("le")
{:ok, []}
iex> Bencoding.decode("de")
{:ok, %{}}
iex> Bencoding.decode("4:spam")
{:ok, "spam"}

If any error happens on decoding, the return value will be {:error, <Error message>}

iex> Bencoding.decode("d")
{:error, "Malformed bencoding string \"d\""}
iex> Bencoding.decode("i3ee")
{:error, "Malformed bencoding string \"i3ee\""}
iex> Bencoding.decode("ie")
{:error, "Malformed bencoding string \"ie\""}

Encoding Data

To encode elixir data into bencoding-encoded data, the Bencoding.encode/1 function should be used. Upon success it returns a tuple with :ok and the encoded string.

iex> Bencoding.encode(3)
{:ok, "i3e"}
iex> Bencoding.encode([])
{:ok, "le"}
iex> Bencoding.encode(%{})
{:ok, "de"}
iex> Bencoding.encode("spam")
{:ok, "4:spam"}

If an error occurs during encoding, a tuple with :error and an error message is returned instead.

iex> Bencoding.encode(%{1 => "invalid"}) 
{:error, "Dictionary keys must be strings"}