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mod_echo.erl
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mod_echo.erl
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%%%----------------------------------------------------------------------
%%% File : mod_echo.erl
%%% Author : Alexey Shchepin <alexey@process-one.net>
%%% Purpose : Simple ejabberd module.
%%% Created : 15 Jan 2003 by Alexey Shchepin <alexey@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2010 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
%%%
%%%----------------------------------------------------------------------
-module(mod_echo).
-author('alexey@process-one.net').
-behaviour(gen_server).
-behaviour(gen_mod).
%% API
-export([start_link/2, start/2, stop/1]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
-include_lib("exmpp/include/exmpp.hrl").
-include("ejabberd.hrl").
-record(state, {host, client_version}).
-define(PROCNAME, ejabberd_mod_echo).
%%====================================================================
%% API
%%====================================================================
%%--------------------------------------------------------------------
%% Function: start_link() -> {ok,Pid} | ignore | {error,Error}
%% Description: Starts the server
%%--------------------------------------------------------------------
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]},
temporary,
1000,
worker,
[?MODULE]},
supervisor:start_child(ejabberd_sup, ChildSpec).
stop(Host) ->
Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
gen_server:call(Proc, stop),
supervisor:terminate_child(ejabberd_sup, Proc),
supervisor:delete_child(ejabberd_sup, Proc).
%%====================================================================
%% gen_server callbacks
%%====================================================================
%%--------------------------------------------------------------------
%% Function: init(Args) -> {ok, State} |
%% {ok, State, Timeout} |
%% ignore |
%% {stop, Reason}
%% Description: Initiates the server
%%--------------------------------------------------------------------
init([Host, Opts]) ->
MyHost = gen_mod:expand_host_name(Host, Opts, "echo"),
ClientVersion = gen_mod:get_opt(client_version, Opts, false),
ejabberd_router:register_route(MyHost),
{ok, #state{host = MyHost, client_version = ClientVersion}}.
%%--------------------------------------------------------------------
%% Function: %% handle_call(Request, From, State) -> {reply, Reply, State} |
%% {reply, Reply, State, Timeout} |
%% {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, Reply, State} |
%% {stop, Reason, State}
%% Description: Handling call messages
%%--------------------------------------------------------------------
handle_call(stop, _From, State) ->
{stop, normal, ok, State}.
%%--------------------------------------------------------------------
%% Function: handle_cast(Msg, State) -> {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State}
%% Description: Handling cast messages
%%--------------------------------------------------------------------
handle_cast(_Msg, State) ->
{noreply, State}.
%%--------------------------------------------------------------------
%% Function: handle_info(Info, State) -> {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State}
%% Description: Handling all non call/cast messages
%%--------------------------------------------------------------------
handle_info({route, From, To, Packet}, State) ->
Packet2 = case exmpp_jid:node(From) of
undefined -> exmpp_stanza:reply_with_error(Packet, 'bad-request');
_ -> Packet
end,
do_client_version(State#state.client_version, To, From),
ejabberd_router:route(To, From, Packet2),
{noreply, State};
handle_info(_Info, State) ->
{noreply, State}.
%%--------------------------------------------------------------------
%% Function: terminate(Reason, State) -> void()
%% Description: This function is called by a gen_server when it is about to
%% terminate. It should be the opposite of Module:init/1 and do any necessary
%% cleaning up. When it returns, the gen_server terminates with Reason.
%% The return value is ignored.
%%--------------------------------------------------------------------
terminate(_Reason, State) ->
ejabberd_router:unregister_route(State#state.host),
ok.
%%--------------------------------------------------------------------
%% Func: code_change(OldVsn, State, Extra) -> {ok, NewState}
%% Description: Convert process state when code is changed
%%--------------------------------------------------------------------
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%--------------------------------------------------------------------
%% Example of routing XMPP packets using Erlang's message passing
%%--------------------------------------------------------------------
%% To enable this educational example, configure the module option
%% client_version like this:
%% {modules, [
%% {mod_echo, [{client_version, true}]},
%% ...
%% ]}.
%% ejabberd provides a method to receive XMPP packets using Erlang's
%% message passing mechanism.
%%
%% The packets received by ejabberd are sent
%% to the local destination process by sending an Erlang message.
%% This means that you can receive XMPP stanzas in an Erlang process
%% using Erlang's Receive, as long as this process is registered in
%% ejabberd as the process which handles the destination JID.
%%
%% This example function is called when a client queries the echo service.
%% This function then sends a query to the client, and waits 5 seconds to
%% receive an answer. The answer will only be accepted if it was sent
%% using exactly the same JID. We add a (mostly) random resource to
%% try to guarantee that the received response matches the request sent.
%% Finally, the received response is printed in the ejabberd log file.
do_client_version(false, _From, _To) ->
ok;
do_client_version(true, From, To) ->
%% It is important to identify this process and packet
Random_resource = integer_to_list(random:uniform(100000)),
From2 = exmpp_jid:full(From,Random_resource),
%% Build an iq:query request
Request = #xmlel{ns = ?NS_SOFT_VERSION, name = 'query'},
Packet = exmpp_stanza:set_recipient(
exmpp_iq:get(?NS_JABBER_CLIENT, Request),
To),
%% Send the request
ejabberd_router:route(From2, To, Packet),
%% Wait to receive the response
%% It is very important to only accept a packet which is the
%% response to the request that he sent
Els = receive {route, To, From2, IQ} ->
#xmlel{ns = ?NS_SOFT_VERSION, name = 'query', children = List} = exmpp_iq:get_payload(IQ),
List
after 5000 -> % Timeout in miliseconds: 5 seconds
[]
end,
Values = [{Name, exmpp_xml:get_cdata_as_list(El)} || #xmlel{name = Name} = El <- Els],
%% Print in log
Values_string1 = [io_lib:format("~n~s: ~p", [N, V]) || {N, V} <- Values],
Values_string2 = lists:concat(Values_string1),
?INFO_MSG("Information of the client: ~s~s", [exmpp_jid:to_binary(To), Values_string2]).