%%%----------------------------------------------------------------------
%%% File : mod_caps.erl
%%% Author : Magnus Henoch <henoch@dtek.chalmers.se>
%%% Purpose : Request and cache Entity Capabilities (XEP-0115)
%%% Created : 7 Oct 2006 by Magnus Henoch <henoch@dtek.chalmers.se>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2009 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., 59 Temple Place, Suite 330, Boston, MA
%%% 02111-1307 USA
%%%
%%% 2009, improvements from Process-One to support correct PEP handling
%%% through s2s, use less memory, and speedup global caps handling
%%%----------------------------------------------------------------------
-module(mod_caps).
-author('henoch@dtek.chalmers.se').
-behaviour(gen_server).
-behaviour(gen_mod).
-export([read_caps/1,
get_caps/1,
note_caps/3,
wait_caps/2,
clear_caps/1,
get_features/2,
get_user_resources/2,
handle_disco_response/3]).
%% gen_mod callbacks
-export([start/2, start_link/2,
stop/1]).
%% gen_server callbacks
-export([init/1,
handle_info/2,
handle_call/3,
handle_cast/2,
terminate/2,
code_change/3
]).
%% hook handlers
-export([receive_packet/3,
receive_packet/4,
presence_probe/3,
remove_connection/3]).
-include("ejabberd.hrl").
-include("jlib.hrl").
-define(PROCNAME, ejabberd_mod_caps).
-define(DICT, dict).
-define(CAPS_QUERY_TIMEOUT, 60000). % 1mn without answer, consider client never answer
-record(caps, {node, version, exts}).
-record(caps_features, {node_pair, features = []}).
-record(user_caps, {jid, caps}).
-record(user_caps_resources, {uid, resource}).
-record(state, {host,
disco_requests = ?DICT:new(),
feature_queries = []}).
%% read_caps takes a list of XML elements (the child elements of a
%% <presence/> stanza) and returns an opaque value representing the
%% Entity Capabilities contained therein, or the atom nothing if no
%% capabilities are advertised.
read_caps(Els) ->
read_caps(Els, nothing).
read_caps([{xmlelement, "c", Attrs, _Els} | Tail], Result) ->
case xml:get_attr_s("xmlns", Attrs) of
?NS_CAPS ->
Node = xml:get_attr_s("node", Attrs),
Version = xml:get_attr_s("ver", Attrs),
Exts = string:tokens(xml:get_attr_s("ext", Attrs), " "),
read_caps(Tail, #caps{node = Node, version = Version, exts = Exts});
_ ->
read_caps(Tail, Result)
end;
read_caps([{xmlelement, "x", Attrs, _Els} | Tail], Result) ->
case xml:get_attr_s("xmlns", Attrs) of
?NS_MUC_USER ->
nothing;
_ ->
read_caps(Tail, Result)
end;
read_caps([_ | Tail], Result) ->
read_caps(Tail, Result);
read_caps([], Result) ->
Result.
%% get_caps reads user caps from database
%% here we handle a simple retry loop, to avoid race condition
%% when asking caps while we still did not called note_caps
%% timeout is set to 10s
%% this is to be improved, but without altering performances.
%% if we did not get user presence 10s after getting presence_probe
%% we assume it has no caps
get_caps(LJID) ->
get_caps(LJID, 5).
get_caps(_, 0) ->
nothing;
get_caps(LJID, Retry) ->
case catch mnesia:dirty_read({user_caps, jid_to_binary(LJID)}) of
[#user_caps{caps=waiting}] ->
timer:sleep(2000),
get_caps(LJID, Retry-1);
[#user_caps{caps=Caps}] ->
Caps;
_ ->
nothing
end.
%% clear_caps removes user caps from database
clear_caps(JID) ->
{U, S, R} = jlib:jid_tolower(JID),
BJID = jid_to_binary(JID),
BUID = jid_to_binary({U, S, []}),
catch mnesia:dirty_delete({user_caps, BJID}),
catch mnesia:dirty_delete_object(#user_caps_resources{uid = BUID, resource = list_to_binary(R)}),
ok.
%% give default user resource
get_user_resources(LUser, LServer) ->
case catch mnesia:dirty_read({user_caps_resources, jid_to_binary({LUser, LServer, []})}) of
{'EXIT', _} ->
[];
Resources ->
lists:map(fun(#user_caps_resources{resource=R}) -> binary_to_list(R) end, Resources)
end.
%% note_caps should be called to make the module request disco
%% information. Host is the host that asks, From is the full JID that
%% sent the caps packet, and Caps is what read_caps returned.
note_caps(Host, From, Caps) ->
case Caps of
nothing ->
ok;
_ ->
Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
gen_server:cast(Proc, {note_caps, From, Caps})
end.
%% wait_caps should be called just before note_caps
%% it allows to lock get_caps usage for code using presence_probe
%% that may run before we get any chance to note_caps.
wait_caps(Host, From) ->
Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
gen_server:cast(Proc, {wait_caps, From}).
%% get_features returns a list of features implied by the given caps
%% record (as extracted by read_caps). It may block, and may signal a
%% timeout error.
get_features(Host, Caps) ->
case Caps of
nothing ->
[];
#caps{} ->
Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
gen_server:call(Proc, {get_features, Caps})
end.
start_link(Host, Opts) ->
Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
gen_server:start_link({local, Proc}, ?MODULE, [Host, Opts], []).
start(Host, Opts) ->
Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
ChildSpec =
{Proc,
{?MODULE, start_link, [Host, Opts]},
transient,
1000,
worker,
[?MODULE]},
supervisor:start_child(ejabberd_sup, ChildSpec).
stop(Host) ->
Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
gen_server:call(Proc, stop).
receive_packet(From, To, {xmlelement, "presence", Attrs, Els}) ->
case xml:get_attr_s("type", Attrs) of
"probe" ->
ok;
"error" ->
ok;
"invisible" ->
ok;
"subscribe" ->
ok;
"subscribed" ->
ok;
"unsubscribe" ->
ok;
"unsubscribed" ->
ok;
"unavailable" ->
{_, S1, _} = jlib:jid_tolower(From),
case jlib:jid_tolower(To) of
{_, S1, _} -> ok;
_ -> clear_caps(From)
end;
%% TODO: probe client, and clean only if no answers
%% as far as protocol does not allow inter-server communication to
%% let remote server handle it's own caps to decide which user is to be
%% notified, we must keep a cache of online status of external contacts
%% this is absolutely not scallable, but we have no choice for now
%% we can only use unavailable presence, but if remote user just remove a local user
%% from its roster, then it's considered as offline, so he does not receive local PEP
%% anymore until he login again.
%% This is tracked in EJAB-943
_ ->
note_caps(To#jid.lserver, From, read_caps(Els))
end;
receive_packet(_, _, _) ->
ok.
receive_packet(_JID, From, To, Packet) ->
receive_packet(From, To, Packet).
presence_probe(From, To, _) ->
wait_caps(To#jid.lserver, From).
remove_connection(_SID, JID, _Info) ->
clear_caps(JID).
jid_to_binary(JID) ->
{U, S, R} = jlib:jid_tolower(JID),
list_to_binary(jlib:jid_to_string({U, S, R})).
caps_to_binary(#caps{node = Node, version = Version, exts = Exts}) ->
BExts = [list_to_binary(Ext) || Ext <- Exts],
#caps{node = list_to_binary(Node), version = list_to_binary(Version), exts = BExts}.
node_to_binary(Node, SubNode) ->
{list_to_binary(Node), list_to_binary(SubNode)}.
features_to_binary(L) -> [list_to_binary(I) || I <- L].
binary_to_features(L) -> [binary_to_list(I) || I <- L].
%%====================================================================
%% gen_server callbacks
%%====================================================================
init([Host, _Opts]) ->
mnesia:create_table(caps_features,
[{disc_copies, [node()]},
{attributes, record_info(fields, caps_features)}]),
mnesia:create_table(user_caps,
[{ram_copies, [node()]},
{attributes, record_info(fields, user_caps)}]),
mnesia:create_table(user_caps_resources,
[{ram_copies, [node()]},
{type, bag},
{attributes, record_info(fields, user_caps_resources)}]),
mnesia:delete_table(user_caps_default),
mnesia:clear_table(user_caps), % clean in case of explicitely set to disc_copies
mnesia:clear_table(user_caps_resources), % clean in case of explicitely set to disc_copies
ejabberd_hooks:add(user_receive_packet, Host, ?MODULE, receive_packet, 30),
ejabberd_hooks:add(s2s_receive_packet, Host, ?MODULE, receive_packet, 30),
ejabberd_hooks:add(presence_probe_hook, Host, ?MODULE, presence_probe, 20),
ejabberd_hooks:add(sm_remove_connection_hook, Host, ?MODULE, remove_connection, 20),
{ok, #state{host = Host}}.
maybe_get_features(#caps{node = Node, version = Version, exts = Exts}) ->
SubNodes = [Version | Exts],
%% Make sure that we have all nodes we need to know.
%% If a single one is missing, we wait for more disco
%% responses.
case lists:foldl(fun(SubNode, Acc) ->
case Acc of
fail -> fail;
_ ->
case mnesia:dirty_read({caps_features, {Node, SubNode}}) of
[] -> fail;
[#caps_features{features = Features}] -> Features ++ Acc %% TODO binary
end
end
end, [], SubNodes) of
fail -> wait;
Features -> {ok, Features}
end.
timestamp() ->
{MegaSecs, Secs, _MicroSecs} = now(),
MegaSecs * 1000000 + Secs.
handle_call({get_features, Caps}, From, State) ->
case maybe_get_features(Caps) of
{ok, Features} ->
{reply, binary_to_features(Features), State};
wait ->
gen_server:cast(self(), visit_feature_queries),
Timeout = timestamp() + 10,
FeatureQueries = State#state.feature_queries,
NewFeatureQueries = [{From, Caps, Timeout} | FeatureQueries],
NewState = State#state{feature_queries = NewFeatureQueries},
{noreply, NewState}
end;
handle_call(stop, _From, State) ->
{stop, normal, ok, State}.
handle_cast({note_caps, From,
#caps{node = Node, version = Version, exts = Exts} = Caps},
#state{host = Host, disco_requests = Requests} = State) ->
%% XXX: this leads to race conditions where ejabberd will send
%% lots of caps disco requests.
{U, S, R} = jlib:jid_tolower(From),
BJID = jid_to_binary(From),
mnesia:transaction(fun() ->
mnesia:write(#user_caps{jid = BJID, caps = caps_to_binary(Caps)}),
case ejabberd_sm:get_user_resources(U, S) of
[] ->
% only store resources of caps aware external contacts
BUID = jid_to_binary({U, S, []}),
mnesia:write(#user_caps_resources{uid = BUID, resource = list_to_binary(R)});
_ ->
ok
end
end),
%% Now, find which of these are not already in the database.
SubNodes = [Version | Exts],
case lists:foldl(fun(SubNode, Acc) ->
case mnesia:dirty_read({caps_features, node_to_binary(Node, SubNode)}) of
[] ->
[SubNode | Acc];
_ ->
Acc
end
end, [], SubNodes) of
[] ->
{noreply, State};
Missing ->
%% For each unknown caps "subnode", we send a disco request.
NewRequests = lists:foldl(
fun(SubNode, Dict) ->
ID = randoms:get_string(),
Stanza =
{xmlelement, "iq",
[{"type", "get"},
{"id", ID}],
[{xmlelement, "query",
[{"xmlns", ?NS_DISCO_INFO},
{"node", lists:concat([Node, "#", SubNode])}],
[]}]},
ejabberd_local:register_iq_response_handler
(Host, ID, ?MODULE, handle_disco_response),
ejabberd_router:route(jlib:make_jid("", Host, ""), From, Stanza),
timer:send_after(?CAPS_QUERY_TIMEOUT, self(), {disco_timeout, ID}),
?DICT:store(ID, node_to_binary(Node, SubNode), Dict)
end, Requests, Missing),
{noreply, State#state{disco_requests = NewRequests}}
end;
handle_cast({wait_caps, From}, State) ->
BJID = jid_to_binary(From),
mnesia:dirty_write(#user_caps{jid = BJID, caps = waiting}),
{noreply, State};
handle_cast({disco_response, From, _To,
#iq{type = Type, id = ID,
sub_el = SubEls}},
#state{disco_requests = Requests} = State) ->
case {Type, SubEls} of
{result, [{xmlelement, "query", _Attrs, Els}]} ->
case ?DICT:find(ID, Requests) of
{ok, BinaryNode} ->
Features =
lists:flatmap(fun({xmlelement, "feature", FAttrs, _}) ->
[xml:get_attr_s("var", FAttrs)];
(_) ->
[]
end, Els),
mnesia:dirty_write(#caps_features{node_pair = BinaryNode, features = features_to_binary(Features)}),
gen_server:cast(self(), visit_feature_queries);
error ->
?DEBUG("ID '~s' matches no query", [ID])
end;
{error, _} ->
%% XXX: if we get error, we cache empty feature not to probe the client continuously
case ?DICT:find(ID, Requests) of
{ok, BinaryNode} ->
mnesia:dirty_write(#caps_features{node_pair = BinaryNode}),
gen_server:cast(self(), visit_feature_queries);
error ->
?DEBUG("ID '~s' matches no query", [ID])
end;
%gen_server:cast(self(), visit_feature_queries),
%?DEBUG("Error IQ reponse from ~s:~n~p", [jlib:jid_to_string(From), SubEls]);
{result, _} ->
?DEBUG("Invalid IQ contents from ~s:~n~p", [jlib:jid_to_string(From), SubEls]);
_ ->
%% Can't do anything about errors
ok
end,
NewRequests = ?DICT:erase(ID, Requests),
{noreply, State#state{disco_requests = NewRequests}};
handle_cast({disco_timeout, ID}, #state{host = Host, disco_requests = Requests} = State) ->
%% do not wait a response anymore for this IQ, client certainly will never answer
NewRequests = case ?DICT:is_key(ID, Requests) of
true ->
ejabberd_local:unregister_iq_response_handler(Host, ID),
?DICT:erase(ID, Requests);
false ->
Requests
end,
{noreply, State#state{disco_requests = NewRequests}};
handle_cast(visit_feature_queries, #state{feature_queries = FeatureQueries} = State) ->
Timestamp = timestamp(),
NewFeatureQueries =
lists:foldl(fun({From, Caps, Timeout}, Acc) ->
case maybe_get_features(Caps) of
wait when Timeout > Timestamp -> [{From, Caps, Timeout} | Acc];
wait -> Acc;
{ok, Features} ->
gen_server:reply(From, Features),
Acc
end
end, [], FeatureQueries),
{noreply, State#state{feature_queries = NewFeatureQueries}}.
handle_disco_response(From, To, IQ) ->
#jid{lserver = Host} = To,
Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
gen_server:cast(Proc, {disco_response, From, To, IQ}).
handle_info(_Info, State) ->
{noreply, State}.
terminate(_Reason, State) ->
Host = State#state.host,
ejabberd_hooks:delete(user_receive_packet, Host, ?MODULE, receive_packet, 30),
ejabberd_hooks:delete(s2s_receive_packet, Host, ?MODULE, receive_packet, 30),
ejabberd_hooks:delete(presence_probe_hook, Host, ?MODULE, presence_probe, 20),
ejabberd_hooks:delete(sm_remove_connection_hook, Host, ?MODULE, remove_connection, 20),
ok.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
