3 files changed, 112 insertions, 0 deletions
diff --git a/lib/pleroma/captcha/captcha.ex b/lib/pleroma/captcha/captcha.ex
new file mode 100644
index 000000000..df33406ee
--- /dev/null
+++ b/lib/pleroma/captcha/captcha.ex
@@ -0,0 +1,51 @@
+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)
+
+    {: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
+
+  defp method, do: Pleroma.Config.get!([__MODULE__, :method])
+end
diff --git a/lib/pleroma/captcha/captcha_service.ex b/lib/pleroma/captcha/captcha_service.ex
new file mode 100644
index 000000000..ae1d6e7c7
--- /dev/null
+++ b/lib/pleroma/captcha/captcha_service.ex
@@ -0,0 +1,24 @@
+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
+end
diff --git a/lib/pleroma/captcha/kocaptcha.ex b/lib/pleroma/captcha/kocaptcha.ex
new file mode 100644
index 000000000..abccbf6d3
--- /dev/null
+++ b/lib/pleroma/captcha/kocaptcha.ex
@@ -0,0 +1,37 @@
+defmodule Pleroma.Captcha.Kocaptcha do
+  alias Pleroma.Captcha.Service
+  @behaviour Service
+
+  @ets __MODULE__.Ets
+
+  @impl Service
+  def new() do
+    endpoint = Pleroma.Config.get!([__MODULE__, :endpoint])
+    case HTTPoison.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"]})
+
+        %{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
+end