mod_tombstones: New module to keep deleted users and rooms tombstones

ejabberd_auth: New check_register_user hook to allow blocking account
registration when a tombstone exists.

mod_muc_room: The room_destroyed hook must provide room persistent option,
because only persistent rooms should generate a tombstone,
temporary ones should not.
And the persistent option should not be completely overwritten, as we must
still known its real value even when room is being destroyed.

mod_tombstones.erl: This could be committed to ejabberd-contrib instead of
upstream ejabberd git repository.

Example configuration:

modules:
  mod_tombstones:
    room_tombstone_expiry: 30 days
    user_tombstone_expiry: 365 days

include/mod_muc_room.hrl

@@ -44,7 +44,7 @@
     allow_visitor_nickchange             = true :: boolean(),
     public                               = true :: boolean(),
     public_list                          = true :: boolean(),
-    persistent                           = false :: boolean(),
+    persistent                           = false :: boolean() | {destroying, boolean()},
     moderated                            = true :: boolean(),
     captcha_protected                    = false :: boolean(),
     members_by_default                   = true :: boolean(),

src/ejabberd_auth.erl

@@ -293,6 +293,8 @@ try_register(User, Server, Password) ->
 		false ->
 		    case ejabberd_router:is_my_host(LServer) of
 			true ->
+			    case ejabberd_hooks:run_fold(check_register_user, LServer, true, [User, Server, Password]) of
+				true ->
 			    case lists:foldl(
 				   fun(_, ok) ->
 					   ok;
@@ -307,6 +309,9 @@ try_register(User, Server, Password) ->
 				{error, _} = Err ->
 				    Err
 			    end;
+				false ->
+				    {error, not_allowed}
+			    end;
 			false ->
 			    {error, not_allowed}
 		    end

src/ejabberd_web_admin.erl

@@ -1726,7 +1726,7 @@ make_command_raw_value(Name, Request, BaseArguments) ->
               raw_value |
               raw_and_value} |
              {input_name_append, [binary()]} |
-             {force_execution, boolean()} |
+             {force_execution, boolean() | undefined} |
              {table_options, {PageSize :: integer(), RemainingPath :: [binary()]}} |
              {result_named, boolean()} |
              {result_links,
@@ -1737,7 +1737,7 @@ make_command_raw_value(Name, Request, BaseArguments) ->
              {style, normal | danger}.
 make_command2(Name, Request, BaseArguments, Options) ->
     Only = proplists:get_value(only, Options, all),
-    ForceExecution = proplists:get_value(force_execution, Options, false),
+    ForceExecution = proplists:get_value(force_execution, Options, undefined),
     InputNameAppend = proplists:get_value(input_name_append, Options, []),
     Resultnamed = proplists:get_value(result_named, Options, false),
     ResultLinks = proplists:get_value(result_links, Options, []),
@@ -1791,6 +1791,8 @@ make_command2(Name,
         case {ForceExecution, ResultFormatApi} of
             {true, _} ->
                 auto;
+            {false, _} ->
+                manual;
             {_, {_, rescode}} ->
                 manual;
             {_, {_, restuple}} ->

src/mod_muc_room.erl

@@ -540,7 +540,7 @@ normal_state({route, <<"">>,
 		case NewStateData of
 		    stop ->
 			Conf = StateData#state.config,
-			{stop, normal, StateData#state{config = Conf#config{persistent = false}}};
+			{stop, normal, StateData#state{config = Conf#config{persistent = {destroying, Conf#config.persistent}}}};
 		    _ when NewStateData#state.just_created ->
 			close_room_if_temporary_and_empty(NewStateData);
 		    _ ->
@@ -736,7 +736,7 @@ handle_event({destroy, Reason}, _StateName,
 	      [jid:encode(StateData#state.jid), Reason]),
     add_to_log(room_existence, destroyed, StateData),
     Conf = StateData#state.config,
-    {stop, shutdown, StateData#state{config = Conf#config{persistent = false}}};
+    {stop, shutdown, StateData#state{config = Conf#config{persistent = {destroying, Conf#config.persistent}}}};
 handle_event(destroy, StateName, StateData) ->
     ?INFO_MSG("Destroyed MUC room ~ts",
 	      [jid:encode(StateData#state.jid)]),
@@ -856,7 +856,7 @@ handle_sync_event({muc_unsubscribe, From}, _From, StateName,
 	     from = From, sub_els = [#muc_unsubscribe{}]},
     case process_iq_mucsub(From, IQ, StateData) of
 	{result, _, stop} ->
-	    {stop, normal, StateData#state{config = Conf#config{persistent = false}}};
+	    {stop, normal, StateData#state{config = Conf#config{persistent = {destroying, Conf#config.persistent}}}};
 	{result, _, NewState} ->
 	    {reply, ok, StateName, NewState};
 	{ignore, NewState} ->
@@ -1015,8 +1015,10 @@ terminate(Reason, _StateName,
 	    _ ->
 		add_to_log(room_existence, stopped, StateData),
 		case (StateData#state.config)#config.persistent of
-		    false ->
-			ejabberd_hooks:run(room_destroyed, LServer, [LServer, Room, Host]);
+                    false ->
+			ejabberd_hooks:run(room_destroyed, LServer, [LServer, Room, Host, false]);
+                    {destroying, Persistent} ->
+			ejabberd_hooks:run(room_destroyed, LServer, [LServer, Room, Host, Persistent]);
 		    _ ->
 			ok
 		end