feat: make handle_command/2 optional

Default to respond with "500 Unknown command".
sntran · Mar 11, 2021 · c184f73 · c184f73
1 parent f0e2d4a
commit c184f73
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Showing 3 changed files with 18 additions and 16 deletions.
diff --git a/lib/gen_nntp.ex b/lib/gen_nntp.ex
@@ -120,6 +120,7 @@ defmodule GenNNTP do
     handle_ARTICLE: 2,
     handle_HEAD: 2,
     handle_BODY: 2,
-    handle_STAT: 2
+    handle_STAT: 2,
+    handle_command: 2
   ]
 end
diff --git a/src/gen_nntp.erl b/src/gen_nntp.erl
@@ -149,7 +149,8 @@
   handle_ARTICLE/2,
   handle_HEAD/2,
   handle_BODY/2,
-  handle_STAT/2
+  handle_STAT/2,
+  handle_command/2
 ]).
 
 %% ==================================================================
@@ -615,15 +616,20 @@ handle_command(<<"QUIT">>, Client) ->
 handle_command(Command, Client) ->
   #client{module = Module, state = State} = Client,
 
-  case Module:handle_command(Command, State) of
-    {reply, Reply, State1} ->
-      {reply, Reply, Client#client{state = State1}};
-    {noreply, State1} ->
-      {noreply, Client#client{state = State1}};
-    {stop, Reason, State1} ->
-      {stop, Reason, Client#client{state = State1}};
-    {stop, Reason, Reply, State1} ->
-      {stop, Reason, Reply, Client#client{state = State1}}
+  case erlang:function_exported(Module, handle_command, 2) of
+    false ->
+      {reply, <<"500 Unknown command">>, State};
+    true ->
+      case Module:handle_command(Command, State) of
+        {reply, Reply, State1} ->
+          {reply, Reply, Client#client{state = State1}};
+        {noreply, State1} ->
+          {noreply, Client#client{state = State1}};
+        {stop, Reason, State1} ->
+          {stop, Reason, Client#client{state = State1}};
+        {stop, Reason, Reply, State1} ->
+          {stop, Reason, Reply, Client#client{state = State1}}
+      end
   end.
 
 % Trim the leading whitespace if any.

diff --git a/test/support/test_nntp_server.ex b/test/support/test_nntp_server.ex
@@ -170,11 +170,6 @@ defmodule TestNNTPServer do
     end
   end
 
-  @impl GenNNTP
-  def handle_command(_command, state) do
-    {:noreply, state}
-  end
-
   defp maybe_apply(server, fun, args, default_reply) do
     case Access.get(server, fun) do
       nil ->