Add basic webfinger.

lib/pleroma/web/router.ex

@@ -19,6 +19,10 @@ defmodule Pleroma.Web.Router do
     plug Pleroma.Plugs.AuthenticationPlug, %{fetcher: &Pleroma.Web.Router.user_fetcher/1}
   end
 
+  pipeline :well_known do
+    plug :accepts, ["xml", "xrd+xml"]
+  end
+
   scope "/api", Pleroma.Web do
     pipe_through :api
 
@@ -49,4 +53,11 @@ defmodule Pleroma.Web.Router do
     post "/statuses/retweet/:id", TwitterAPI.Controller, :retweet
     post "/qvitter/update_avatar", TwitterAPI.Controller, :update_avatar
   end
+
+  scope "/.well-known", Pleroma.Web do
+    pipe_through :well_known
+
+    get "/host-meta", WebFinger.WebFingerController, :host_meta
+    get "/webfinger", WebFinger.WebFingerController, :webfinger
+  end
 end

lib/pleroma/web/web.ex

@@ -61,12 +61,17 @@ defmodule Pleroma.Web do
     apply(__MODULE__, which, [])
   end
 
+  def host do
+    settings = Application.get_env(:pleroma, Pleroma.Web.Endpoint)
+    settings
+    |> Keyword.fetch!(:url)
+    |> Keyword.fetch!(:host)
+  end
+
   def base_url do
     settings = Application.get_env(:pleroma, Pleroma.Web.Endpoint)
-    host =
-      settings
-      |> Keyword.fetch!(:url)
-      |> Keyword.fetch!(:host)
+
+    host = host()
 
     protocol = settings |> Keyword.fetch!(:protocol)
 

lib/pleroma/web/web_finger/web_finger.ex

@@ -0,0 +1,38 @@
+defmodule Pleroma.Web.WebFinger do
+  alias Pleroma.XmlBuilder
+  alias Pleroma.User
+
+  def host_meta() do
+    base_url  = Pleroma.Web.base_url
+    {
+      :XRD, %{ xmlns: "http://docs.oasis-open.org/ns/xri/xrd-1.0" },
+      {
+        :Link, %{ rel: "lrdd", type: "application/xrd+xml", template: "#{base_url}/.well-known/webfinger?resource={uri}"  }
+      }
+    }
+    |> XmlBuilder.to_doc
+  end
+
+  def webfinger(resource) do
+    host = Pleroma.Web.host
+    regex = ~r/acct:(?<username>\w+)@#{host}/
+    case Regex.named_captures(regex, resource) do
+      %{"username" => username} ->
+        user = User.get_cached_by_nickname(username)
+        {:ok, represent_user(user)}
+      _ -> nil
+    end
+  end
+
+  def represent_user(user) do
+    {
+      :XRD, %{xmlns: "http://docs.oasis-open.org/ns/xri/xrd-1.0"},
+      [
+        {:Subject, "acct:#{user.nickname}@#{Pleroma.Web.host}"},
+        {:Alias, user.ap_id},
+        {:Link, %{rel: "http://schemas.google.com/g/2010#updates-from", type: "application/atom+xml", href: "#{user.ap_id}.atom"}}
+      ]
+    }
+    |> XmlBuilder.to_doc
+  end
+end

lib/pleroma/web/web_finger/web_finger_controller.ex

@@ -0,0 +1,21 @@
+defmodule Pleroma.Web.WebFinger.WebFingerController do
+  use Pleroma.Web, :controller
+
+  alias Pleroma.Web.WebFinger
+
+  def host_meta(conn, _params) do
+    xml = WebFinger.host_meta
+
+    conn
+    |> put_resp_content_type("application/xrd+xml")
+    |> send_resp(200, xml)
+  end
+
+  def webfinger(conn, %{"resource" => resource}) do
+    {:ok, response} = Pleroma.Web.WebFinger.webfinger(resource)
+
+    conn
+    |> put_resp_content_type("application/xrd+xml")
+    |> send_resp(200, response)
+  end
+end

lib/xml_builder.ex

@@ -0,0 +1,42 @@
+defmodule Pleroma.XmlBuilder do
+  def to_xml({tag, attributes, content}) do
+    open_tag = make_open_tag(tag, attributes)
+
+    content_xml = to_xml(content)
+
+    "<#{open_tag}>#{content_xml}</#{tag}>"
+  end
+
+  def to_xml({tag, %{} = attributes}) do
+    open_tag = make_open_tag(tag, attributes)
+
+    "<#{open_tag} />"
+  end
+
+  def to_xml({tag, content}), do: to_xml({tag, %{}, content})
+
+  def to_xml(content) when is_binary(content) do
+    to_string(content)
+  end
+
+  def to_xml(content) when is_list(content) do
+    for element <- content do
+      to_xml(element)
+    end
+    |> Enum.join
+  end
+
+  def to_xml(%NaiveDateTime{} = time) do
+    NaiveDateTime.to_iso8601(time)
+  end
+
+  def to_doc(content), do: "<?xml version=\"1.0\" encoding=\"UTF-8\"?>" <> to_xml(content)
+
+  defp make_open_tag(tag, attributes) do
+    attributes_string = for {attribute, value} <- attributes do
+      "#{attribute}=\"#{value}\""
+    end |> Enum.join(" ")
+
+    Enum.join([tag, attributes_string], " ") |> String.strip
+  end
+end