Add matching.

README.md

@@ -2,6 +2,34 @@
 
 [Classless Inter-Domain Routing (CIDR)](https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing) for [Elixir](http://www.elixir-lang.org/)
 
+## Setup
+
+To use this library in your project, edit your mix.exs file and add cidr as a dependency:
+
+```elixir
+defp deps do
+  [
+    { :cidr, "~> 0.1.0" }
+  ]
+end
+```
+
+## Usage
+
+Parse an IP address / CIDR:
+```elixir
+iex(1)> cidr = "1.2.3.4/24" |> CIDR.parse
+%CIDR{ip: {1, 2, 3, 4}, mask: 24}
+```
+
+Match against a CIDR:
+```elixir
+iex(2)> cidr |> CIDR.match({1,2,3,100})
+true
+iex(3)> cidr |> CIDR.match({1,2,4,1})
+false
+```
+
 ## License
 
 [MIT License](LICENSE).

lib/cidr.ex

@@ -1,5 +1,7 @@
 defmodule CIDR do
 
+  use Bitwise
+
   @moduledoc """
   Classless Inter-Domain Routing (CIDR)
   """
@@ -18,6 +20,15 @@ defmodule CIDR do
   end
   def is_cidr(_), do: false
 
+  @doc """
+  Checks if an IP address is in the provided CIDR.
+  """
+  def match(%CIDR{ ip: { a0, b0, c0, d0 }, mask: mask } = cidr, { a1, b1, c1, d1 } = ip) do
+    cidr_value = (a0 <<< 24) ||| (b0 <<< 16) ||| (c0 <<< 8) ||| d0
+    ip_value = (a1 <<< 24) ||| (b1 <<< 16) ||| (c1 <<< 8) ||| d1
+    (cidr_value >>> (32 - mask)) == (ip_value >>> (32 - mask))
+  end
+
   def to_cidr(string) when string |> is_bitstring do
     tokens = String.split(string, "/")
     if Enum.count(tokens) == 2 do

mix.exs

@@ -2,11 +2,15 @@ defmodule CIDR.Mixfile do
   use Mix.Project
 
   def project do
-    [app: :cidr,
-     version: "0.0.1",
-     elixir: "~> 1.0",
-     source_url: "https://github.com/c-rack/cidr-elixir",
-     deps: deps]
+    [
+      app: :cidr,
+      version: "0.1.0",
+      elixir: ">= 1.0.2",
+      source_url: "https://github.com/c-rack/cidr-elixir",
+      deps: deps,
+      description: "Classless Inter-Domain Routing (CIDR) for Elixir",
+      package: package
+    ]
   end
 
   # Configuration for the OTP application
@@ -28,4 +32,13 @@ defmodule CIDR.Mixfile do
   defp deps do
     []
   end
+
+  defp package do
+    %{
+      contributors: ["Constantin Rack"],
+      licenses: ["MIT License"],
+      links: %{"Github" => "https://github.com/c-rack/cidr-elixir"}
+    }
+  end
+
 end

test/cidr_test.exs

@@ -33,4 +33,21 @@ defmodule CIDRTest do
     assert "127.0.0.1/24" |> CIDR.parse |> CIDR.is_cidr
   end
 
+  # Match
+
+  test "Matches exactly" do
+    assert ("1.2.3.4" |> CIDR.parse |> CIDR.match({1, 1, 1, 1})) == false
+    assert ("1.2.3.4" |> CIDR.parse |> CIDR.match({1, 2, 3, 3})) == false
+    assert "1.2.3.4" |> CIDR.parse |> CIDR.match({1, 2, 3, 4})
+    assert ("1.2.3.4" |> CIDR.parse |> CIDR.match({1, 2, 3, 5})) == false
+    assert ("1.2.3.4" |> CIDR.parse |> CIDR.match({255, 255, 255, 255})) == false
+  end
+
+  test "Matches /24" do
+    assert "1.2.3.4/24" |> CIDR.parse |> CIDR.match({1, 2, 3, 1})
+    assert "1.2.3.4/24" |> CIDR.parse |> CIDR.match({1, 2, 3, 100})
+    assert "1.2.3.4/24" |> CIDR.parse |> CIDR.match({1, 2, 3, 200})
+    assert "1.2.3.4/24" |> CIDR.parse |> CIDR.match({1, 2, 3, 255})
+  end
+
 end