Add basic webfinger.

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