From 7bbf59625a83ccd1cff50742cc2cc60f5724e9fd Mon Sep 17 00:00:00 2001
From: Alain Zscheile <zseri.devel@ytrizja.de>
Date: Sun, 27 Nov 2022 00:40:44 +0100
Subject: [PATCH] add ability to supply arbitrary filters

---
 lib/floof/application.ex |  4 +++-
 lib/floof/distributor.ex | 23 +++++++++++++++++++----
 mix.exs                  |  3 +++
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/lib/floof/application.ex b/lib/floof/application.ex
index 378c8ad..6d4572d 100644
--- a/lib/floof/application.ex
+++ b/lib/floof/application.ex
@@ -14,6 +14,7 @@ defmodule Floof.Application do
     markers = Application.fetch_env!(:floof, :markers)
     attrs = Application.fetch_env!(:floof, :attrs)
     set_markers = Application.fetch_env!(:floof, :set_markers)
+    extra_filters = Application.fetch_env!(:floof, :extra_filters)
     spool_dir = Application.fetch_env!(:floof, :spool_dir)
     sessions_file = Application.fetch_env!(:floof, :sessions_file)
 
@@ -28,7 +29,8 @@ defmodule Floof.Application do
          Floof.Distributor.fconfig(
            markers: markers,
            attrs: attrs,
-           set_markers: set_markers
+           set_markers: set_markers,
+           extra_filters: extra_filters
          )},
         {Floof.SessionManager, {:sessions, [file: to_charlist(sessions_file)]}}
       ] ++
diff --git a/lib/floof/distributor.ex b/lib/floof/distributor.ex
index bf9de86..6e5e472 100644
--- a/lib/floof/distributor.ex
+++ b/lib/floof/distributor.ex
@@ -12,7 +12,8 @@ defmodule Floof.Distributor do
   Record.defrecord(:fconfig,
     markers: [],
     attrs: [],
-    set_markers: []
+    set_markers: [],
+    extra_filters: []
   )
 
   Record.defrecord(:dstate, fconf: {}, trgs: MapSet.new())
@@ -72,13 +73,27 @@ defmodule Floof.Distributor do
         {:XferBlob, ttl, old_markers, signature, data} = dcd
         set_markers = fconfig(fconf, :set_markers)
         new_markers = Enum.uniq(set_markers ++ old_markers)
-        dcd2 = {:XferBlob, ttl - 1, new_markers, signature, data}
+        dcd = {:XferBlob, ttl - 1, new_markers, signature, data}
+
+        dcd =
+          Enum.reduce(
+            fconfig(fconf, :extra_filters),
+            dcd,
+            fn f, dcdx ->
+              case dcdx do
+                nil -> nil
+                dcdx -> f.(dcdx)
+              end
+            end
+          )
 
         for trg <- trgs do
-          send(trg, {:fwdxfer, {dcdhash, dcd2}})
+          send(trg, {:fwdxfer, {dcdhash, dcd}})
         end
 
-        Floof.SessionManager.set_for_all(dcdhash, dcd2, origin)
+        if ttl > 1 do
+          Floof.SessionManager.set_for_all(dcdhash, dcd, origin)
+        end
       end)
     end
 
diff --git a/mix.exs b/mix.exs
index ca3212d..35e4a75 100644
--- a/mix.exs
+++ b/mix.exs
@@ -34,6 +34,9 @@ defmodule Floof.MixProject do
         # these are the markers of form {:RelativeDistinguishedName, oid-as-list(), value()}
         # which get added to all processed messages
         set_markers: [],
+        # a list of functions which can be used to further filter packets
+        # (by returning nil if unwanted) and modify them
+        extra_filters: [],
         # file locations
         #  the spool dir saves messages in-transit, and is used to prevent RAM OOM
         spool_dir: "mock_spool",