%%%-------------------------------------------------------------------
%%% File : mod_block_strangers.erl
%%% Author : Alexey Shchepin <alexey@process-one.net>
%%% Purpose : Block packets from non-subscribers
%%% Created : 25 Dec 2016 by Alexey Shchepin <alexey@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2018 ProcessOne
%%%
%%% This program is free software; you can redistribute it and/or
%%% modify it under the terms of the GNU General Public License as
%%% published by the Free Software Foundation; either version 2 of the
%%% License, or (at your option) any later version.
%%%
%%% This program is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
%%% General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License along
%%% with this program; if not, write to the Free Software Foundation, Inc.,
%%% 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
%%%
%%%-------------------------------------------------------------------
-module(mod_block_strangers).
-author('alexey@process-one.net').
-behaviour(gen_mod).
%% API
-export([start/2, stop/1, reload/3,
depends/2, mod_opt_type/1]).
-export([filter_packet/1, filter_offline_msg/1]).
-include("xmpp.hrl").
-include("ejabberd.hrl").
-include("logger.hrl").
-define(SETS, gb_sets).
start(Host, _Opts) ->
ejabberd_hooks:add(user_receive_packet, Host,
?MODULE, filter_packet, 25),
ejabberd_hooks:add(offline_message_hook, Host,
?MODULE, filter_offline_msg, 25).
stop(Host) ->
ejabberd_hooks:delete(user_receive_packet, Host,
?MODULE, filter_packet, 25),
ejabberd_hooks:delete(offline_message_hook, Host,
?MODULE, filter_offline_msg, 25).
reload(_Host, _NewOpts, _OldOpts) ->
ok.
filter_packet({#message{from = From} = Msg, State} = Acc) ->
LFrom = jid:tolower(From),
LBFrom = jid:remove_resource(LFrom),
#{pres_a := PresA} = State,
case (?SETS):is_element(LFrom, PresA)
orelse (?SETS):is_element(LBFrom, PresA)
orelse sets_bare_member(LBFrom, PresA) of
false ->
case check_message(Msg) of
allow -> Acc;
deny -> {stop, {drop, State}}
end;
true ->
Acc
end;
filter_packet(Acc) ->
Acc.
filter_offline_msg({_Action, #message{} = Msg} = Acc) ->
case check_message(Msg) of
allow -> Acc;
deny -> {stop, {drop, Msg}}
end.
check_message(#message{from = From, to = To, lang = Lang} = Msg) ->
LServer = To#jid.lserver,
AllowLocalUsers =
gen_mod:get_module_opt(LServer, ?MODULE, allow_local_users, true),
case (Msg#message.body == [] andalso
Msg#message.subject == [])
orelse ((AllowLocalUsers orelse From#jid.luser == <<"">>) andalso
ejabberd_router:is_my_host(From#jid.lserver)) of
false ->
case check_subscription(From, To) of
none ->
Drop = gen_mod:get_module_opt(LServer, ?MODULE, drop, true),
Log = gen_mod:get_module_opt(LServer, ?MODULE, log, false),
if
Log ->
?INFO_MSG("~s message from stranger ~s to ~s",
[if Drop -> "Rejecting";
true -> "Allow"
end,
jid:encode(From), jid:encode(To)]);
true ->
ok
end,
if
Drop ->
Txt = <<"Messages from strangers are rejected">>,
Err = xmpp:err_policy_violation(Txt, Lang),
ejabberd_router:route_error(Msg, Err),
deny;
true ->
allow
end;
some ->
allow
end;
true ->
allow
end.
-spec check_subscription(jid(), jid()) -> none | some.
check_subscription(From, To) ->
{LocalUser, LocalServer, _} = jid:tolower(To),
{RemoteUser, RemoteServer, _} = jid:tolower(From),
case ejabberd_hooks:run_fold(
roster_get_jid_info, LocalServer,
{none, []}, [LocalUser, LocalServer, From]) of
{none, _} when RemoteUser == <<"">> ->
none;
{none, _} ->
case gen_mod:get_module_opt(LocalServer, ?MODULE,
allow_transports, true) of
true ->
%% Check if the contact's server is in the roster
case ejabberd_hooks:run_fold(
roster_get_jid_info, LocalServer,
{none, []},
[LocalUser, LocalServer, jid:make(RemoteServer)]) of
{none, _} -> none;
_ -> some
end;
false ->
none
end;
_ ->
some
end.
sets_bare_member({U, S, <<"">>} = LBJID, Set) ->
case ?SETS:next(sets_iterator_from(LBJID, Set)) of
{{U, S, _}, _} -> true;
_ -> false
end.
-ifdef(GB_SETS_ITERATOR_FROM).
sets_iterator_from(Element, Set) ->
?SETS:iterator_from(Element, Set).
-else.
%% Copied from gb_sets.erl
%% TODO: Remove after dropping R17 support
sets_iterator_from(S, {_, T}) ->
iterator_from(S, T, []).
iterator_from(S, {K, _, T}, As) when K < S ->
iterator_from(S, T, As);
iterator_from(_, {_, nil, _} = T, As) ->
[T | As];
iterator_from(S, {_, L, _} = T, As) ->
iterator_from(S, L, [T | As]);
iterator_from(_, nil, As) ->
As.
-endif.
depends(_Host, _Opts) ->
[].
mod_opt_type(drop) ->
fun (B) when is_boolean(B) -> B end;
mod_opt_type(log) ->
fun (B) when is_boolean(B) -> B end;
mod_opt_type(allow_local_users) ->
fun (B) when is_boolean(B) -> B end;
mod_opt_type(allow_transports) ->
fun (B) when is_boolean(B) -> B end;
mod_opt_type(_) -> [drop, log, allow_local_users, allow_transports].
