Merge branch 'captcha' into 'develop'

Captcha

See merge request pleroma/pleroma!550

config/config.exs

@@ -10,6 +10,13 @@
 
 config :pleroma, Pleroma.Repo, types: Pleroma.PostgresTypes
 
+config :pleroma, Pleroma.Captcha,
+  enabled: false,
+  seconds_retained: 180,
+  method: Pleroma.Captcha.Kocaptcha
+
+config :pleroma, Pleroma.Captcha.Kocaptcha, endpoint: "https://captcha.kotobank.ch"
+
 # Upload configuration
 config :pleroma, Pleroma.Upload,
   uploader: Pleroma.Uploaders.Local,

config/config.md

@@ -7,7 +7,7 @@ If you run Pleroma with ``MIX_ENV=prod`` the file is ``prod.secret.exs``, otherw
 * `uploader`: Select which `Pleroma.Uploaders` to use
 * `filters`: List of `Pleroma.Upload.Filter` to use.
 * `base_url`: The base URL to access a user-uploaded file. Useful when you want to proxy the media files via another host.
-* `proxy_remote`: If you're using a remote uploader, Pleroma will proxy media requests instead of redirecting to it.
+* `proxy_remote`: If you\'re using a remote uploader, Pleroma will proxy media requests instead of redirecting to it.
 * `proxy_opts`: Proxy options, see `Pleroma.ReverseProxy` documentation.
 
 Note: `strip_exif` has been replaced by `Pleroma.Upload.Filter.Mogrify`.
@@ -163,3 +163,15 @@ Web Push Notifications configuration. You can use the mix task `mix web_push.gen
 * ``subject``: a mailto link for the administrative contact. It’s best if this email is not a personal email address, but rather a group email so that if a person leaves an organization, is unavailable for an extended period, or otherwise can’t respond, someone else on the list can.
 * ``public_key``: VAPID public key
 * ``private_key``: VAPID private key
+
+## Pleroma.Captcha
+* `enabled`: Whether the captcha should be shown on registration
+* `method`: The method/service to use for captcha
+* `seconds_retained`: The time in seconds for which the captcha is valid (stored in the cache)
+
+### Pleroma.Captcha.Kocaptcha
+Kocaptcha is a very simple captcha service with a single API endpoint,
+the source code is here: https://github.com/koto-bank/kocaptcha. The default endpoint
+`https://captcha.kotobank.ch` is hosted by the developer.
+
+* `endpoint`: the kocaptcha endpoint to use

config/test.exs

@@ -7,6 +7,12 @@
   url: [port: 4001],
   server: true
 
+# Disable captha for tests
+config :pleroma, Pleroma.Captcha,
+  enabled: true,
+  # A fake captcha service for tests
+  method: Pleroma.Captcha.Mock
+
 # Print only warnings and errors during test
 config :logger, level: :warn
 

lib/pleroma/application.ex

@@ -24,6 +24,7 @@ def start(_type, _args) do
         # Start the Ecto repository
         supervisor(Pleroma.Repo, []),
         worker(Pleroma.Emoji, []),
+        worker(Pleroma.Captcha, []),
         worker(
           Cachex,
           [

lib/pleroma/captcha/captcha.ex

@@ -0,0 +1,66 @@
+defmodule Pleroma.Captcha do
+  use GenServer
+
+  @ets_options [:ordered_set, :private, :named_table, {:read_concurrency, true}]
+
+  @doc false
+  def start_link() do
+    GenServer.start_link(__MODULE__, [], name: __MODULE__)
+  end
+
+  @doc false
+  def init(_) do
+    # Create a ETS table to store captchas
+    ets_name = Module.concat(method(), Ets)
+    ^ets_name = :ets.new(Module.concat(method(), Ets), @ets_options)
+
+    # Clean up old captchas every few minutes
+    seconds_retained = Pleroma.Config.get!([__MODULE__, :seconds_retained])
+    Process.send_after(self(), :cleanup, 1000 * seconds_retained)
+
+    {:ok, nil}
+  end
+
+  @doc """
+  Ask the configured captcha service for a new captcha
+  """
+  def new() do
+    GenServer.call(__MODULE__, :new)
+  end
+
+  @doc """
+  Ask the configured captcha service to validate the captcha
+  """
+  def validate(token, captcha) do
+    GenServer.call(__MODULE__, {:validate, token, captcha})
+  end
+
+  @doc false
+  def handle_call(:new, _from, state) do
+    enabled = Pleroma.Config.get([__MODULE__, :enabled])
+
+    if !enabled do
+      {:reply, %{type: :none}, state}
+    else
+      {:reply, method().new(), state}
+    end
+  end
+
+  @doc false
+  def handle_call({:validate, token, captcha}, _from, state) do
+    {:reply, method().validate(token, captcha), state}
+  end
+
+  @doc false
+  def handle_info(:cleanup, state) do
+    :ok = method().cleanup()
+
+    seconds_retained = Pleroma.Config.get!([__MODULE__, :seconds_retained])
+    # Schedule the next clenup
+    Process.send_after(self(), :cleanup, 1000 * seconds_retained)
+
+    {:noreply, state}
+  end
+
+  defp method, do: Pleroma.Config.get!([__MODULE__, :method])
+end

lib/pleroma/captcha/captcha_service.ex

@@ -0,0 +1,28 @@
+defmodule Pleroma.Captcha.Service do
+  @doc """
+  Request new captcha from a captcha service.
+
+  Returns:
+
+  Service-specific data for using the newly created captcha
+  """
+  @callback new() :: map
+
+  @doc """
+  Validated the provided captcha solution.
+
+  Arguments:
+  * `token` the captcha is associated with
+  * `captcha` solution of the captcha to validate
+
+  Returns:
+
+  `true` if captcha is valid, `false` if not
+  """
+  @callback validate(token :: String.t(), captcha :: String.t()) :: boolean
+
+  @doc """
+  This function is called periodically to clean up old captchas
+  """
+  @callback cleanup() :: :ok
+end

lib/pleroma/captcha/kocaptcha.ex

@@ -0,0 +1,67 @@
+defmodule Pleroma.Captcha.Kocaptcha do
+  alias Calendar.DateTime
+
+  alias Pleroma.Captcha.Service
+  @behaviour Service
+
+  @ets __MODULE__.Ets
+
+  @impl Service
+  def new() do
+    endpoint = Pleroma.Config.get!([__MODULE__, :endpoint])
+
+    case Tesla.get(endpoint <> "/new") do
+      {:error, _} ->
+        %{error: "Kocaptcha service unavailable"}
+
+      {:ok, res} ->
+        json_resp = Poison.decode!(res.body)
+
+        token = json_resp["token"]
+
+        true =
+          :ets.insert(
+            @ets,
+            {token, json_resp["md5"], DateTime.now_utc() |> DateTime.Format.unix()}
+          )
+
+        %{type: :kocaptcha, token: token, url: endpoint <> json_resp["url"]}
+    end
+  end
+
+  @impl Service
+  def validate(token, captcha) do
+    with false <- is_nil(captcha),
+         [{^token, saved_md5, _}] <- :ets.lookup(@ets, token),
+         true <- :crypto.hash(:md5, captcha) |> Base.encode16() == String.upcase(saved_md5) do
+      # Clear the saved value
+      :ets.delete(@ets, token)
+
+      true
+    else
+      _ -> false
+    end
+  end
+
+  @impl Service
+  def cleanup() do
+    seconds_retained = Pleroma.Config.get!([Pleroma.Captcha, :seconds_retained])
+    # If the time in ETS is less than current_time - seconds_retained, then the time has
+    # already passed
+    delete_after =
+      DateTime.subtract!(DateTime.now_utc(), seconds_retained) |> DateTime.Format.unix()
+
+    :ets.select_delete(
+      @ets,
+      [
+        {
+          {:_, :_, :"$1"},
+          [{:<, :"$1", {:const, delete_after}}],
+          [true]
+        }
+      ]
+    )
+
+    :ok
+  end
+end

lib/pleroma/web/router.ex

@@ -99,6 +99,7 @@ defmodule Pleroma.Web.Router do
     get("/password_reset/:token", UtilController, :show_password_reset)
     post("/password_reset", UtilController, :password_reset)
     get("/emoji", UtilController, :emoji)
+    get("/captcha", UtilController, :captcha)
   end
 
   scope "/api/pleroma/admin", Pleroma.Web.AdminAPI do

lib/pleroma/web/twitter_api/controllers/util_controller.ex

@@ -284,4 +284,8 @@ def delete_account(%{assigns: %{user: user}} = conn, params) do
         json(conn, %{error: msg})
     end
   end
+
+  def captcha(conn, _params) do
+    json(conn, Pleroma.Captcha.new())
+  end
 end

lib/pleroma/web/twitter_api/twitter_api.ex

@@ -132,9 +132,25 @@ def register_user(params) do
       bio: User.parse_bio(params["bio"]),
       email: params["email"],
       password: params["password"],
-      password_confirmation: params["confirm"]
+      password_confirmation: params["confirm"],
+      captcha_solution: params["captcha_solution"],
+      captcha_token: params["captcha_token"]
     }
 
+    captcha_enabled = Pleroma.Config.get([Pleroma.Captcha, :enabled])
+    # true if captcha is disabled or enabled and valid, false otherwise
+    captcha_ok =
+      if !captcha_enabled do
+        true
+      else
+        Pleroma.Captcha.validate(params[:captcha_token], params[:captcha_solution])
+      end
+
+    # Captcha invalid
+    if not captcha_ok do
+      # I have no idea how this error handling works
+      {:error, %{error: Jason.encode!(%{captcha: ["Invalid CAPTCHA"]})}}
+    else
       registrations_open = Pleroma.Config.get([:instance, :registrations_open])
 
       # no need to query DB if registration is open
@@ -166,6 +182,7 @@ def register_user(params) do
           {:error, "Expired token"}
       end
     end
+  end
 
   def password_reset(nickname_or_email) do
     with true <- is_binary(nickname_or_email),

test/captcha_test.exs

@@ -0,0 +1,40 @@
+defmodule Pleroma.CaptchaTest do
+  use ExUnit.Case
+
+  import Tesla.Mock
+
+  alias Pleroma.Captcha.Kocaptcha
+
+  @ets_options [:ordered_set, :private, :named_table, {:read_concurrency, true}]
+
+  describe "Kocaptcha" do
+    setup do
+      ets_name = Kocaptcha.Ets
+      ^ets_name = :ets.new(ets_name, @ets_options)
+
+      mock(fn
+        %{method: :get, url: "https://captcha.kotobank.ch/new"} ->
+          json(%{
+            md5: "63615261b77f5354fb8c4e4986477555",
+            token: "afa1815e14e29355e6c8f6b143a39fa2",
+            url: "/captchas/afa1815e14e29355e6c8f6b143a39fa2.png"
+          })
+      end)
+
+      :ok
+    end
+
+    test "new and validate" do
+      assert Kocaptcha.new() == %{
+               type: :kocaptcha,
+               token: "afa1815e14e29355e6c8f6b143a39fa2",
+               url: "https://captcha.kotobank.ch/captchas/afa1815e14e29355e6c8f6b143a39fa2.png"
+             }
+
+      assert Kocaptcha.validate(
+               "afa1815e14e29355e6c8f6b143a39fa2",
+               "7oEy8c"
+             )
+    end
+  end
+end

test/support/captcha_mock.ex

@@ -0,0 +1,13 @@
+defmodule Pleroma.Captcha.Mock do
+  alias Pleroma.Captcha.Service
+  @behaviour Service
+
+  @impl Service
+  def new(), do: %{type: :mock}
+
+  @impl Service
+  def validate(_token, _captcha), do: true
+
+  @impl Service
+  def cleanup(), do: :ok
+end