Add a dummy route for /.well-known/host-meta

This was removed from the diaspora_federation gem, since it's not used
for the federation/discovery anymore since a long time. But old versions
of the ConnectionTester up to version 0.7.17 still check if this route
exist or else they mark the pod as offline. So lets add a dummy
host-meta with an empty response back, so the ConnectionTester is happy
again until we can remove this workaround again.

app/controllers/node_info_controller.rb

@@ -20,4 +20,14 @@ class NodeInfoController < ApplicationController
       format.all { @statistics = NodeInfoPresenter.new("1.0") }
     end
   end
+
+  # TODO: this is only a dummy endpoint, because old versions of the ConnectionTester (<= 0.7.17.0)
+  #  checked for this endpoint. Remove this endpoint again once most pods are updated to >= 0.7.18.0
+  def host_meta
+    render xml: <<~XML
+      <?xml version="1.0" encoding="UTF-8"?>
+      <XRD xmlns="http://docs.oasis-open.org/ns/xri/xrd-1.0">
+      </XRD>
+    XML
+  end
 end

config/initializers/cors.rb

@@ -11,7 +11,6 @@ Rails.application.config.middleware.insert_before 0, Rack::Cors do
   allow do
     origins "*"
     resource "/api/*", methods: :any
-    resource "/.well-known/host-meta"
     resource "/.well-known/webfinger"
     resource "/.well-known/openid-configuration"
   end

config/routes.rb

@@ -213,6 +213,7 @@ Rails.application.routes.draw do
   get ".well-known/nodeinfo", to: "node_info#jrd"
   get "nodeinfo/:version",    to: "node_info#document", as: "node_info", constraints: {version: /\d+\.\d+/}
   get "statistics",           to: "node_info#statistics"
+  get ".well-known/host-meta", to: "node_info#host_meta"
 
   # Terms
   if AppConfig.settings.terms.enable? || Rails.env.test?