add captcha, controller, images

.iex.exs

@@ -1,2 +1,3 @@
 alias Philomena.{Repo, Comments.Comment, Posts.Post, Images.Image, Tags.Tag, Users.User}
-import Ecto.Query
+import Ecto.Query
+import Ecto.Changeset

lib/philomena/application.ex

@@ -14,7 +14,8 @@ defmodule Philomena.Application do
       PhilomenaWeb.Endpoint,
       # Starts a worker by calling: Philomena.Worker.start_link(arg)
       # {Philomena.Worker, arg},
-      Pow.Store.Backend.MnesiaCache
+      Pow.Store.Backend.MnesiaCache,
+      {Redix, name: :redix}
     ]
 
     # See https://hexdocs.pm/elixir/Supervisor.html

lib/philomena/captcha.ex

@@ -0,0 +1,130 @@
+defmodule Philomena.Captcha do
+  defstruct [:image_base64, :solution, :solution_id]
+
+  @numbers ~W(1 2 3 4 5 6)  
+  @images ~W(1 2 3 4 5 6)
+  @base_path File.cwd!() <> "/assets/static/images/captcha"
+
+  @number_files %{
+    "1" => @base_path <> "/1.png",
+    "2" => @base_path <> "/2.png",
+    "3" => @base_path <> "/3.png",
+    "4" => @base_path <> "/4.png",
+    "5" => @base_path <> "/5.png",
+    "6" => @base_path <> "/6.png"
+  }
+
+  @image_files %{
+    "1" => @base_path <> "/i1.png",
+    "2" => @base_path <> "/i2.png",
+    "3" => @base_path <> "/i3.png",
+    "4" => @base_path <> "/i4.png",
+    "5" => @base_path <> "/i5.png",
+    "6" => @base_path <> "/i6.png"
+  }
+
+  @background_file @base_path <> "/background.png"
+
+  @geometry %{
+    1 => "+0+0",   2 => "+120+0",   3 => "+240+0",
+    4 => "+0+120", 5 => "+120+120", 6 => "+240+120",
+    7 => "+0+240", 8 => "+120+240", 9 => "+240+240"
+  }
+
+  @distortion_1 [
+    ~W"-implode .1",
+    ~W"-implode -.1"
+  ]
+
+  @distortion_2 [
+    ~W"-swirl 10",
+    ~W"-swirl -10",
+    ~W"-swirl 20",
+    ~W"-swirl -20"
+  ]
+
+  @distortion_3 [
+    ~W"-wave 5x180",
+    ~W"-wave 5x126",
+    ~W"-wave 10x180",
+    ~W"-wave 10x126"
+  ]
+
+  def create do
+    solution =
+      Enum.zip(@numbers, Enum.shuffle(@images))
+      |> Map.new()
+
+    # 3x3 render grid
+    grid = Enum.shuffle(@numbers ++ [nil, nil, nil])
+
+    # Base arguments
+    args = [
+      "-page", "360x360",
+      @background_file
+    ]
+
+    # Individual grid files
+    files =
+      grid
+      |> Enum.with_index()
+      |> Enum.flat_map(fn {num, index} ->
+        if num do
+          [
+            "(", @image_files[solution[num]], ")", "-geometry", @geometry[index + 1], "-composite",
+            "(", @number_files[num], ")", "-geometry", @geometry[index + 1], "-composite"
+          ]
+        else
+          []
+        end
+      end)
+
+    # Distortions for more unpredictability
+    distortions =
+      [
+        Enum.random(@distortion_1),
+        Enum.random(@distortion_2),
+        Enum.random(@distortion_3)
+      ]
+      |> Enum.shuffle()
+      |> List.flatten()
+
+    jpeg = ~W"-quality 8 jpeg:-"
+
+    {image, 0} = System.cmd("convert", args ++ files ++ distortions ++ jpeg)
+    image = image |> Base.encode64()
+
+    # Store solution in redis to prevent reuse
+    # Solutions are valid for 10 minutes
+    solution_id =
+      :crypto.strong_rand_bytes(12)
+      |> Base.encode16(case: :lower)
+    solution_id = "cp_" <> solution_id
+
+    {:ok, _ok} = Redix.command(:redix, ["SET", solution_id, Jason.encode!(solution)])
+    {:ok, _ok} = Redix.command(:redix, ["EXPIRE", solution_id, 600])
+
+    %Philomena.Captcha{
+      image_base64: image,
+      solution: solution,
+      solution_id: solution_id
+    }
+  end
+
+  def valid_solution?(<<"cp_", _rest::binary>> = solution_id, solution) do
+    # Delete key immediately. This may race, but should
+    # have minimal impact if the race succeeds.
+    with {:ok, sol} <- Redix.command(:redix, ["GET", solution_id]),
+         {:ok, _del} <- Redix.command(:redix, ["DEL", solution_id]),
+         {:ok, sol} <- Jason.decode(to_string(sol))
+    do
+      Map.equal?(solution, sol)
+    else
+      _ ->
+        false
+    end
+  end
+
+  def valid_solution?(_solution_id, _solution),
+    do: false
+end

lib/philomena_web/controllers/captcha_controller.ex

@@ -0,0 +1,11 @@
+defmodule PhilomenaWeb.CaptchaController do
+  use PhilomenaWeb, :controller
+
+  alias Philomena.Captcha
+
+  def create(conn, _params) do
+    captcha = Captcha.create()
+
+    render(conn, "create.html", captcha: captcha, layout: false)
+  end
+end

lib/philomena_web/router.ex

@@ -67,6 +67,7 @@ defmodule PhilomenaWeb.Router do
     end
     resources "/filters", FilterController
     resources "/profiles", ProfileController, only: [:show]
+    resources "/captchas", CaptchaController, only: [:create]
 
     get "/:id", ImageController, :show
   end

lib/philomena_web/templates/captcha/create.html.slime

@@ -0,0 +1,20 @@
+elixir:
+  options = [
+    "Applejack": 1,
+    "Fluttershy": 2,
+    "Pinkie Pie": 3,
+    "Rainbow Dash": 4,
+    "Rarity": 5,
+    "Twilight Sparkle": 6
+  ]
+
+div
+  = hidden_input :captcha, :id, value: @captcha.solution_id
+  img src="data:image/jpeg;base64,#{@captcha.image_base64}"
+
+  = for i <- (1..6) do
+    .field
+      label> for="captcha_sln[#{i}]"
+        | Name of pony with cutie mark #
+        = i
+      = select :captcha, "sln[#{i}]", options, class: "input"

lib/philomena_web/templates/pow/session/new.html.slime

@@ -19,6 +19,10 @@ h1 Sign in
     = checkbox f, :persistent_session
     = label f, :persistent_session, "Remember me"
 
+  .field
+    = checkbox f, :captcha, class: "js-captcha", value: 0
+    = label f, :captcha, "I am not a robot!"
+
   = submit "Sign in", class: "button"
 
 p

lib/philomena_web/views/captcha_view.ex

@@ -0,0 +1,3 @@
+defmodule PhilomenaWeb.CaptchaView do
+  use PhilomenaWeb, :view
+end

mix.exs

@@ -54,7 +54,8 @@ defmodule Philomena.MixProject do
       {:canary, "~> 1.1.1"},
       {:scrivener_ecto, "~> 2.0"},
       {:pbkdf2, "~> 2.0"},
-      {:qrcode, "~> 0.1.5"}
+      {:qrcode, "~> 0.1.5"},
+      {:redix, "~> 0.10.2"}
     ]
   end
 

mix.lock

@@ -43,6 +43,7 @@
   "pow": {:hex, :pow, "1.0.13", "5ca3e8d9fecca037bfb0ea3b8dde070cc319746498e844d59fc209d461b0d426", [:mix], [{:ecto, "~> 2.2 or ~> 3.0", [hex: :ecto, repo: "hexpm", optional: false]}, {:phoenix, "~> 1.3.0 or ~> 1.4.0", [hex: :phoenix, repo: "hexpm", optional: false]}, {:phoenix_html, ">= 2.0.0 and <= 3.0.0", [hex: :phoenix_html, repo: "hexpm", optional: false]}, {:plug, ">= 1.5.0 and < 2.0.0", [hex: :plug, repo: "hexpm", optional: true]}], "hexpm"},
   "qrcode": {:hex, :qrcode, "0.1.5", "551271830515c150f34568345b060c625deb0e6691db2a01b0a6de3aafc93886", [:mix], [], "hexpm"},
   "ranch": {:hex, :ranch, "1.7.1", "6b1fab51b49196860b733a49c07604465a47bdb78aa10c1c16a3d199f7f8c881", [:rebar3], [], "hexpm"},
+  "redix": {:hex, :redix, "0.10.2", "a9eabf47898aa878650df36194aeb63966d74f5bd69d9caa37babb32dbb93c5d", [:mix], [{:telemetry, "~> 0.4.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm"},
   "retry": {:hex, :retry, "0.13.0", "bb9b2713f70f39337837852337ad280c77662574f4fb852a8386c269f3d734c4", [:mix], [], "hexpm"},
   "scrivener": {:hex, :scrivener, "2.7.0", "fa94cdea21fad0649921d8066b1833d18d296217bfdf4a5389a2f45ee857b773", [:mix], [], "hexpm"},
   "scrivener_ecto": {:hex, :scrivener_ecto, "2.2.0", "53d5f1ba28f35f17891cf526ee102f8f225b7024d1cdaf8984875467158c9c5e", [:mix], [{:ecto, "~> 3.0", [hex: :ecto, repo: "hexpm", optional: false]}, {:scrivener, "~> 2.4", [hex: :scrivener, repo: "hexpm", optional: false]}], "hexpm"},