Initial commit

.gitignore

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+/_build
+/deps
+erl_crash.dump
+*.ez

.travis.yml

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+language: erlang
+otp_release:
+  - 17.0
+before_install:
+  - git clone https://github.com/elixir-lang/elixir
+  - cd elixir
+  - git checkout v1.0.0
+  - cd ..
+  - make -C elixir
+before_script:
+  - export PATH="`pwd`/elixir/bin:$PATH"
+  - mix local.hex --force
+script: "MIX_ENV=test mix do deps.get, test"

LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2014 Alexander Ivanov
+
+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.

README.md

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+Wire
+====
+
+[![Build Status](https://travis-ci.org/alehander42/wire.svg)](https://travis-ci.org/alehander42/wire/)
+
+Wire is an elixir package for decoding and encoding
+bittorrent peer wire protocol messages.
+
+A message is represented in the library as a keyword list with
+`:type`: the type of the message (`:keep_alive`, :`not_interested`, etc)
+and the other fields of the message, e.g.
+
+```elixir
+h = [type: :have, piece_index: 4]
+```
+
+```elixir
+
+Wire.encode [type: :interested] # <<0, 0, 0, 1, 2>>
+Wire.encode [type: :bitfield, field: <<0, 4>>] # <<0, 0, 0, 3, 5, 0, 4>>
+```
+
+`decode_messages` decodes a binary containing 0 or more messages and
+returns a list of messages and the remaining bytes
+
+```elixir
+
+
+Wire.decode_messages(<<0, 0, 0, 6, 5, 0, 2, 4, 3, 1>>)
+# {[[type: :bitfield, field: <<0, 2, 4, 3, 1>>]], <<>>}
+Wire.decode_messages(<< 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0xf, 5 >>)
+# {[[type: :keep_alive], [type: :interested]], <<0, 0, 0, 0xf, 5>>})
+
+
+```
+

config/config.exs

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+# This file is responsible for configuring your application
+# and its dependencies with the aid of the Mix.Config module.
+use Mix.Config
+
+# This configuration is loaded before any dependency and is restricted
+# to this project. If another project depends on this project, this
+# file won't be loaded nor affect the parent project. For this reason,
+# if you want to provide default values for your application for third-
+# party users, it should be done in your mix.exs file.
+
+# Sample configuration:
+#
+#     config :logger, :console,
+#       level: :info,
+#       format: "$date $time [$level] $metadata$message\n",
+#       metadata: [:user_id]
+
+# It is also possible to import configuration files, relative to this
+# directory. For example, you can emulate configuration per environment
+# by uncommenting the line below and defining dev.exs, test.exs and such.
+# Configuration from the imported file will override the ones defined
+# here (which is why it is important to import them last).
+#
+#     import_config "#{Mix.env}.exs"

lib/wire.ex

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+defmodule Wire do
+  defdelegate encode(message), to: Wire.Encoder
+  defdelegate decode_messages(message), to: Wire.Decoder
+  defdelegate decode_message(message), to: Wire.Decoder
+end
+
+

lib/wire/decoder.ex

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+defmodule Wire.Decoder do
+
+  @doc ~S"""
+  Parses a binary containing 0 or more messages and
+  returns a list with messages and the unparsed part of the message
+
+  """
+  @spec decode_messages(binary) :: {List.Keyword.t, binary}
+  def decode_messages(binary) do
+    << l :: 32-integer-big-unsigned, rest :: binary >> = binary
+    cond do
+      byte_size(rest) < l ->
+        {[], binary}
+      true ->
+        decode_messages(binary, [])
+    end
+  end
+
+  def decode_messages(s, acc) do
+    << l :: 32-integer-big-unsigned, rest :: binary >> = s
+    if byte_size(rest) < l do
+      { acc, s }
+    else
+      { message, rest } = decode_message(s)
+      if byte_size(rest) > 0 do
+        decode_messages(rest, acc ++ [message])
+      else
+        { acc ++ [message], rest }
+      end
+    end
+  end
+
+  def decode_message(message) do
+    << l :: 32-integer-big-unsigned, rest :: binary >> = message
+
+    if l == 0 do
+      {[type: :keep_alive], rest}
+    else
+      << id, rest :: binary >> = rest
+
+      case id do
+        9 ->
+          << port :: 16-integer-big-unsigned, rest :: binary >> = rest
+          {[type: :port, listen_port: port], rest}
+        7 ->
+          l2 = l - 9
+          << index :: 32-integer-big-unsigned, begin :: 32-integer-big-unsigned,
+             block :: binary-size(l2), rest :: binary >> = rest
+          {[type: :piece, index: index, begin: begin, block: block], rest}
+        id when id in [8, 6] ->
+          << index   :: 32-integer-big-unsigned,
+             begin   :: 32-integer-big-unsigned,
+             length  :: 32-integer-big-unsigned,
+             rest    :: binary >> = rest
+          type = if id == 8 do :cancel else :request end
+          {[type: type, index: index, begin: begin, length: length], rest}
+
+        5 ->
+          l2 = l - 1
+          << field :: binary-size(l2), rest :: binary >> = rest
+          {[type: :bitfield, field: field], rest}
+        4 ->
+          << piece_index :: 32-integer-big-unsigned, rest :: binary >> = rest
+          {[type: :have, piece_index: piece_index], rest}
+        3 ->
+          {[type: :not_interested], rest}
+        2 ->
+          {[type: :interested], rest}
+        1 ->
+          {[type: :unchoke], rest}
+        0 ->
+          {[type: :choke], rest}
+
+      end
+    end
+  end
+end

lib/wire/encoder.ex

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+defmodule Wire.Encoder do
+  def encode(type: :port, listen_port: listen_port) do
+    << 0, 0, 0, 3, listen_port :: 16-integer-big-unsigned, 0 >>
+  end
+
+  def encode(type: request_or_cancel, index: index, begin: begin, length: length) when request_or_cancel in [:cancel, :request] do
+    a = if request_or_cancel == :cancel do 8 else 6 end
+
+    << 0, 0, 0, 0xd, a,
+       index :: 32-integer-big-unsigned,
+       begin :: 32-integer-big-unsigned,
+       length  :: 32-integer-big-unsigned >>
+  end
+
+  def encode(type: :piece, index: index, begin: begin, block: block) do
+    << (9 + byte_size(block)) :: 32-integer-big-unsigned, 8, index :: 32-integer-big-unsigned, begin :: 32-integer-big-unsigned,
+       block :: binary >>
+  end
+
+  def encode(type: :bitfield, field: field) do
+    << (1 + byte_size(field)) :: 32-integer-big-unsigned, 5, field :: binary>>
+  end
+
+  def encode(type: :have, piece_index: piece_index) do
+    << 0, 0, 0, 5, 4, piece_index :: 32-integer-big-unsigned >>
+  end
+
+  def encode(type: :not_interested) do
+    << 0, 0, 0, 1, 3 >>
+  end
+
+  def encode(type: :interested) do
+    << 0, 0, 0, 1, 2 >>
+  end
+
+  def encode(type: :unchoke) do
+    << 0, 0, 0, 1, 1 >>
+  end
+
+  def encode(type: :choke) do
+    << 0, 0, 0, 1, 0 >>
+  end
+
+  def encode(type: :keep_alive) do
+    << 0, 0, 0, 0 >>
+  end
+end

mix.exs

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+defmodule Wire.Mixfile do
+  use Mix.Project
+
+  def project do
+    [app: :wire,
+     version: "0.0.8",
+     elixir: "~> 1.0.0",
+     description: "Encode and decode bittorrent peer wire protocol messages",
+     package: package,
+     deps: deps]
+  end
+
+  defp package do
+    [ contributors: ["alehander42"],
+      licenses: ["MIT"],
+      links: %{"Github" => "https://github.com/alehander42/wire"}]
+  end
+
+  def application do
+    [applications: [:logger]]
+  end
+
+  defp deps do
+    []
+  end
+end

test/decoder_test.exs

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+Code.require_file "test_helper.exs", __DIR__
+
+defmodule WireDecoderTest do
+  use ExUnit.Case, async: True
+
+  import Wire.Decoder, only: [decode_message: 1, decode_messages: 1, decode_messages: 2]
+
+  test "parses keep_alive correctly" do
+    assert decode_message(<< 0, 0, 0, 0 >>)  == {[type: :keep_alive], <<>>}
+  end
+
+  test "parses have correctly" do
+    assert decode_message(<< 0, 0, 0, 5, 4, 0, 0, 0, 96, 0, 96, 3, 5>>) == {[type: :have, piece_index: 96], <<0, 96, 3, 5>>}
+  end
+
+  test "parses interested correctly" do
+    assert decode_message(<< 0, 0, 0, 1, 2 >>) == {[type: :interested], <<>>}
+  end
+
+  test "parses bitfield correctly" do
+    assert decode_message(<< 0, 0, 0, 6, 5, 0, 2, 4, 0, 2 >>) ==
+                {[type: :bitfield, field: <<0, 2, 4, 0, 2>>], <<>>}
+  end
+
+  test "parses unchoke messages" do
+    assert decode_messages(<< 0, 0, 0, 1, 1 >>) == {[[type: :unchoke]], <<>>}
+  end
+
+  test "parses several messages" do
+    assert decode_messages(<< 0, 0, 0, 0, 0, 0, 0, 1, 2 >>) ==
+                          {[[type: :keep_alive], [type: :interested]], <<>>}
+  end
+
+  test "parses a part of a message as rest" do
+    assert decode_messages(<< 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0xf, 5 >>) ==
+                          {[[type: :keep_alive], [type: :interested]], <<0, 0, 0, 0xf, 5>>}
+    assert decode_messages(<< 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 >>) ==
+                          {[[type: :keep_alive], [type: :keep_alive]], <<0, 0, 0, 1>>}
+  end
+
+  test "parses several messages with acc" do
+    assert decode_messages(<< 0, 0, 0, 0, 0, 0, 0, 1>>, []) ==
+                          {[[type: :keep_alive]], <<0, 0, 0, 1>>}
+    assert decode_messages(<< 0, 0, 0, 1, 2, 0, 0, 0, 5>>, [[type: :keep_alive]]) ==
+                          {[[type: :keep_alive], [type: :interested]], <<0, 0, 0, 5>>}
+  end
+end

test/encode_test.exs

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+Code.require_file "test_helper.exs", __DIR__
+
+defmodule WireEncoderTest do
+  use ExUnit.Case, async: True
+
+  import Wire.Encoder, only: [encode: 1]
+
+  test "converts port correctly" do
+    assert encode(type: :port, listen_port: 80) ==
+           << 0, 0, 0, 3, 0, 80, 0 >>
+  end
+
+  test "converts cancel correctly" do
+    assert encode(type: :cancel, index: 2, begin: 0, length: 4) ==
+           << 0, 0, 0, 0xd, 8, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 4 >>
+  end
+
+  test "converts request correctly" do
+    assert encode(type: :request, index: 2, begin: 0, length: 4) ==
+           << 0, 0, 0, 0xd, 6, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 4 >>
+  end
+
+  test "converts bitfield correctly" do
+    assert encode(type: :bitfield, field: << 0 >>) ==
+           << 0, 0, 0, 2, 5, 0 >>
+  end
+
+  test "converts have correctly" do
+    assert encode(type: :have, piece_index: 22) ==
+      << 0, 0, 0, 5, 4, 0, 0, 0, 22 >>
+  end
+
+  test "converts interested correctly" do
+    assert encode(type: :interested) == << 0, 0, 0, 1, 2 >>
+  end
+end
+

test/test_helper.exs

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+ExUnit.start()