api/masto/account: filter embedded nodeinfo

The only kown user is akkoma-fe and it only ever
accesses the software information. For *oma instances
the full, unfiltered nodeinfo data can be quite large
adding unneeded bloat to API responses.
This would have become worse with the duplication of
account data needed for Masto quote post interop.

In case a client we’re not aware of actually uses more fields from
nodeinfo, a new but temporary config setting is provided as a workaround.

Fixes: #827

config/config.exs

@@ -249,6 +249,7 @@ config :pleroma, :instance,
   remote_post_retention_days: 90,
   skip_thread_containment: true,
   limit_to_local_content: :unauthenticated,
+  filter_embedded_nodeinfo: true,
   user_bio_length: 5000,
   user_name_length: 100,
   max_account_fields: 10,

lib/pleroma/config/deprecation_warnings.ex

@@ -43,6 +43,22 @@ defmodule Pleroma.Config.DeprecationWarnings do
     end
   end
 
+  def check_truncated_nodeinfo_in_accounts do
+    if !Config.get!([:instance, :filter_embedded_nodeinfo]) do
+      Logger.warning("""
+      !!!BUG WORKAROUND DETECTED!!!
+      Your config is explicitly disabling filtering of nodeinfo data embedded in other Masto API responses
+
+        config :pleroma, :instance, filter_embedded_nodeinfo: false
+
+      This setting will soon be removed. Any usage of it merely serves as a temporary workaround.
+      Make sure to file a bug telling us which problems you encountered and circumvented by setting this!
+         https://akkoma.dev/AkkomaGang/akkoma/issues
+      We can’t fix bugs we don’t know about.
+      """)
+    end
+  end
+
   def check_exiftool_filter do
     filters = Config.get([Pleroma.Upload]) |> Keyword.get(:filters, [])
 

lib/pleroma/web/mastodon_api/views/account_view.ex

@@ -181,10 +181,19 @@ defmodule Pleroma.Web.MastodonAPI.AccountView do
   end
 
   def render("instance.json", %{instance: %Pleroma.Instances.Instance{} = instance}) do
+    nodeinfo =
+      if Pleroma.Config.get!([:instance, :filter_embedded_nodeinfo]) and instance.nodeinfo do
+        %{}
+        |> maybe_put_nodeinfo(instance.nodeinfo, :version)
+        |> maybe_put_nodeinfo(instance.nodeinfo, :software)
+      else
+        instance.nodeinfo
+      end
+
     %{
       name: instance.host,
       favicon: instance.favicon |> MediaProxy.url(),
-      nodeinfo: instance.nodeinfo
+      nodeinfo: nodeinfo
     }
   end
 
@@ -442,6 +451,17 @@ defmodule Pleroma.Web.MastodonAPI.AccountView do
 
   defp maybe_put_email_address(data, _, _), do: data
 
+  defp maybe_put_nodeinfo(map, nodeinfo, key) do
+    # local nodeinfo uses atom keys, all remote instances string keys
+    val = nodeinfo[key] || nodeinfo[to_string(key)]
+
+    if val do
+      Map.put(map, key, val)
+    else
+      map
+    end
+  end
+
   defp image_url(%{"url" => [%{"href" => href} | _]}), do: href
   defp image_url(_), do: nil
 end

test/pleroma/web/mastodon_api/views/account_view_test.exs

@@ -62,7 +62,7 @@ defmodule Pleroma.Web.MastodonAPI.AccountViewTest do
         instance: %{
           name: "example.com",
           nodeinfo: %{
-            "version" => "2.1"
+            version: "2.1"
           },
           favicon: nil
         },
@@ -135,7 +135,7 @@ defmodule Pleroma.Web.MastodonAPI.AccountViewTest do
                  instance: %{
                    name: "somewhere.example.com",
                    nodeinfo: %{
-                     "version" => "2.0"
+                     version: "2.0"
                    },
                    favicon: "https://example.com/favicon.ico"
                  }