Add some basic webfingering.

lib/pleroma/web/web_finger/web_finger.ex

@@ -2,6 +2,8 @@ defmodule Pleroma.Web.WebFinger do
   alias Pleroma.XmlBuilder
   alias Pleroma.User
   alias Pleroma.Web.OStatus
+  alias Pleroma.Web.XML
+  require Logger
 
   def host_meta() do
     base_url  = Pleroma.Web.base_url
@@ -37,4 +39,39 @@ def represent_user(user) do
     }
     |> XmlBuilder.to_doc
   end
+
+  # FIXME: Make this call the host-meta to find the actual address.
+  defp webfinger_address(domain) do
+    "https://#{domain}/.well-known/webfinger"
+  end
+
+  defp webfinger_from_xml(doc) do
+    magic_key = XML.string_from_xpath(~s{//Link[@rel="magic-public-key"]/@href}, doc)
+    "data:application/magic-public-key," <> magic_key = magic_key
+    topic = XML.string_from_xpath(~s{//Link[@rel="http://schemas.google.com/g/2010#updates-from"]/@href}, doc)
+    subject = XML.string_from_xpath("//Subject", doc)
+    salmon = XML.string_from_xpath(~s{//Link[@rel="salmon"]/@href}, doc)
+    data = %{
+      magic_key: magic_key,
+      topic: topic,
+      subject: subject,
+      salmon: salmon
+    }
+    {:ok, data}
+  end
+
+  def finger(account, getter \\ &HTTPoison.get/3) do
+    [name, domain] = String.split(account, "@")
+    address = webfinger_address(domain)
+    with {:ok, %{status_code: status_code, body: body}} when status_code in 200..299 <- getter.(address, ["Accept": "application/xrd+xml"], [params: [resource: account]]),
+         doc <- XML.parse_document(body),
+         {:ok, data} <- webfinger_from_xml(doc) do
+      {:ok, data}
+    else
+      e ->
+        Logger.debug("Couldn't finger #{account}.")
+        Logger.debug(e)
+        {:error, e}
+    end
+  end
 end

test/fixtures/webfinger.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<XRD xmlns="http://docs.oasis-open.org/ns/xri/xrd-1.0">
+ <Subject>acct:shp@social.heldscal.la</Subject>
+ <Alias>https://social.heldscal.la/user/29191</Alias>
+ <Alias>https://social.heldscal.la/shp</Alias>
+ <Alias>https://social.heldscal.la/index.php/user/29191</Alias>
+ <Alias>https://social.heldscal.la/index.php/shp</Alias>
+ <Link rel="http://webfinger.net/rel/profile-page" type="text/html" href="https://social.heldscal.la/shp"/>
+ <Link rel="http://gmpg.org/xfn/11" type="text/html" href="https://social.heldscal.la/shp"/>
+ <Link rel="describedby" type="application/rdf+xml" href="https://social.heldscal.la/shp/foaf"/>
+ <Link rel="http://apinamespace.org/atom" type="application/atomsvc+xml" href="https://social.heldscal.la/api/statusnet/app/service/shp.xml"/>
+ <Link rel="http://apinamespace.org/twitter" href="https://social.heldscal.la/api/"/>
+ <Link rel="http://specs.openid.net/auth/2.0/provider" href="https://social.heldscal.la/shp"/>
+ <Link rel="http://schemas.google.com/g/2010#updates-from" type="application/atom+xml" href="https://social.heldscal.la/api/statuses/user_timeline/29191.atom"/>
+ <Link rel="magic-public-key" href="data:application/magic-public-key,RSA.wQ3i9UA0qmAxZ0WTIp4a-waZn_17Ez1pEEmqmqoooRsG1_BvpmOvLN0G2tEcWWxl2KOtdQMCiPptmQObeZeuj48mdsDZ4ArQinexY2hCCTcbV8Xpswpkb8K05RcKipdg07pnI7tAgQ0VWSZDImncL6YUGlG5YN8b5TjGOwk2VG8=.AQAB"/>
+ <Link rel="salmon" href="https://social.heldscal.la/main/salmon/user/29191"/>
+ <Link rel="http://salmon-protocol.org/ns/salmon-replies" href="https://social.heldscal.la/main/salmon/user/29191"/>
+ <Link rel="http://salmon-protocol.org/ns/salmon-mention" href="https://social.heldscal.la/main/salmon/user/29191"/>
+ <Link rel="http://ostatus.org/schema/1.0/subscribe" template="https://social.heldscal.la/main/ostatussub?profile={uri}"/>
+</XRD>

test/web/web_finger/web_finger_test.exs

 defmodule Pleroma.Web.WebFingerTest do
   use Pleroma.DataCase
+  alias Pleroma.Web.WebFinger
 
   describe "host meta" do
     test "returns a link to the xml lrdd" do
-      host_info = Pleroma.Web.WebFinger.host_meta
+      host_info = WebFinger.host_meta()
 
       assert String.contains?(host_info, Pleroma.Web.base_url)
     end
   end
+
+  describe "fingering" do
+    test "returns the info for a user" do
+      user = "shp@social.heldscal.la"
+
+      getter = fn(_url, _headers, [params: [resource: ^user]]) ->
+        {:ok, %{status_code: 200, body: File.read!("test/fixtures/webfinger.xml")}}
+      end
+
+      {:ok, data} = WebFinger.finger(user, getter)
+
+      assert data.magic_key == "RSA.wQ3i9UA0qmAxZ0WTIp4a-waZn_17Ez1pEEmqmqoooRsG1_BvpmOvLN0G2tEcWWxl2KOtdQMCiPptmQObeZeuj48mdsDZ4ArQinexY2hCCTcbV8Xpswpkb8K05RcKipdg07pnI7tAgQ0VWSZDImncL6YUGlG5YN8b5TjGOwk2VG8=.AQAB"
+      assert data.topic == "https://social.heldscal.la/api/statuses/user_timeline/29191.atom"
+      assert data.subject == "acct:shp@social.heldscal.la"
+      assert data.salmon == "https://social.heldscal.la/main/salmon/user/29191"
+    end
+  end
 end