src/gsup_client.erl

% simple, blocking/synchronous GSUP client

% (C) 2019 by Harald Welte <laforge@gnumonks.org>
%
% All Rights Reserved
%
% This program is free software; you can redistribute it and/or modify
% it under the terms of the GNU Affero General Public License as
% published by the Free Software Foundation; either version 3 of the
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% GNU General Public License for more details.
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% Additional Permission under GNU AGPL version 3 section 7:
%
% If you modify this Program, or any covered work, by linking or
% combining it with runtime libraries of Erlang/OTP as released by
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-module(gsup_client).

-behaviour(gen_server).

-include_lib("osmo_gsup/include/gsup_protocol.hrl").
-include_lib("osmo_ss7/include/ipa.hrl").

-define(IPAC_PROTO_EXT_GSUP,	{osmo, 5}).
-define(GSUP_TIMEOUT_MS, 5000).

-record(gsupc_state, {
		address,
		port,
		ccmoptions,
		socket,
		ipa_pid
	 }).

-export([start_link/3]).

-export([init/1, handle_call/3, handle_cast/2, handle_info/2]).
-export([code_change/3, terminate/2]).

%% ------------------------------------------------------------------
%% our exported API
%% ------------------------------------------------------------------

start_link(ServerAddr, ServerPort, GsupName) ->
	gen_server:start_link(?MODULE, [ServerAddr, ServerPort, GsupName], [{debug, [trace]}]).

%% ------------------------------------------------------------------
%% gen_server Function Definitions
%% ------------------------------------------------------------------

init([Address, Port, GsupName]) ->
	ipa_proto:init(),
	% register the GSUP codec with the IPA core; ignore result as we might be doing this multiple times
	ipa_proto:register_codec(?IPAC_PROTO_EXT_GSUP, fun gsup_protocol:encode/1, fun gsup_protocol:decode/1),
	lager:info("Connecting to GSUP HLR on IP ~s port ~p~n", [Address, Port]),
        CcmOptions = #ipa_ccm_options{
                serial_number=GsupName,
                unit_id="0/0/0",
                mac_address="00:00:00:00:00:00",
                location="00:00:00:00:00:00",
                unit_type="00:00:00:00:00:00",
                equipment_version="00:00:00:00:00:00",
                sw_version="00:00:00:00:00:00",
                unit_name=GsupName
                },
        State = #gsupc_state{address = Address, port = Port, ccmoptions = CcmOptions, socket = [], ipa_pid = []},
        case connect(State) of
                {ok, State2} -> {ok, State2};
                {error, _, State2} -> {ok, State2, ?GSUP_TIMEOUT_MS}
        end.

connect(State) ->
        #gsupc_state{address = Address, port = Port, ccmoptions = Options} = State,
	case ipa_proto:connect(Address, Port, []) of
		{ok, {Socket, IpaPid}} ->
			ipa_proto:set_ccm_options(Socket, Options),
			lager:info("connected!~n", []),
			true = ipa_proto:register_stream(Socket, ?IPAC_PROTO_EXT_GSUP, {process_id, self()}),
			ipa_proto:unblock(Socket),
			{ok, State#gsupc_state{socket=Socket, ipa_pid=IpaPid}};
		{error, Error} ->
	                lager:info("Failed to GSUP HLR on IP ~s port ~p ~p~n", [Address, Port, Error]),
			{error, Error, State}
	end.

% send a given GSUP message and synchronously wait for message type ExpRes or ExpErr
handle_call({transceive_gsup, GsupMsgTx, ExpRes, ExpErr}, _From, State) ->
	Socket = State#gsupc_state.socket,
	{ok, Imsi} = maps:find(imsi, GsupMsgTx),
	ipa_proto:send(Socket, ?IPAC_PROTO_EXT_GSUP, GsupMsgTx),
	% selective receive for only those GSUP responses we expect
	receive
		{ipa, Socket, ?IPAC_PROTO_EXT_GSUP, GsupMsgRx = #{message_type := ExpRes, imsi := Imsi}} ->
			{reply, GsupMsgRx, State};
		{ipa, Socket, ?IPAC_PROTO_EXT_GSUP, GsupMsgRx = #{message_type := ExpErr, imsi := Imsi}} ->
			{reply, GsupMsgRx, State}
	after ?GSUP_TIMEOUT_MS ->
		{reply, timeout, State}
	end.

handle_cast(Info, S) ->
	error_logger:error_report(["unknown handle_cast", {module, ?MODULE}, {info, Info}, {state, S}]),
	{noreply, S}.

handle_info({ipa_closed, _}, S) ->
	lager:error("GSUP connection has been closed, Reconnecting in 5sec."),
	{noreply, S, ?GSUP_TIMEOUT_MS};
handle_info(timeout, S) ->
	case connect(S) of
		{ok, State} -> {noreply, State};
		{error, _, State} -> {noreply, State, ?GSUP_TIMEOUT_MS}
	end;

handle_info(Info, S) ->
	error_logger:error_report(["unknown handle_info", {module, ?MODULE}, {info, Info}, {state, S}]),
	{noreply, S}.

terminate(Reason, _S) ->
	lager:info("terminating ~p with reason ~p~n", [?MODULE, Reason]).

code_change(_OldVsn, State, _Extra) ->
	{ok, State}.