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|
% MTP2 Initial Alignment Control according to Q.703 Figure 4 / Figure 9
% (C) 2011-2012 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
% 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 Affero General Public License
% along with this program. If not, see <http://www.gnu.org/licenses/>.
-module(mtp2_iac).
-author('Harald Welte <laforge@gnumonks.org>').
-behaviour(gen_fsm).
% gen_fsm exports
-export([init/1, terminate/3, code_change/4, handle_event/3, handle_info/3]).
% states in this FSM
-export([idle/2, not_aligned/2, aligned/2, proving/2]).
% Timeouts in milliseconds According to Q.703 / Section 12.3
-define(M2PA_T1_DEF, 50000).
-define(M2PA_T2_DEF, 150000).
-define(M2PA_T3_DEF, 2000).
-define(M2PA_T4N_DEF, 8200).
-define(M2PA_T4E_DEF, 500).
-record(iac_state, {
t2_timeout,
t3_timeout,
t4_timeout,
t4_timeout_pn,
t4_timeout_pe,
t2, t3, t4,
emergency,
cp,
further_prov,
lsc_pid,
aerm_pid,
txc_pid
}).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% gen_fsm callbacks
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
init([Lsc, Aerm, Txc]) ->
IacState = #iac_state{t2_timeout = ?M2PA_T2_DEF,
t3_timeout = ?M2PA_T3_DEF,
t4_timeout_pn = ?M2PA_T4N_DEF,
t4_timeout_pe = ?M2PA_T4E_DEF,
emergency = 0,
cp = 0,
further_prov = 1,
lsc_pid = Lsc,
aerm_pid = Aerm,
txc_pid = Txc},
{ok, idle, IacState}.
terminate(Reason, State, _LoopDat) ->
io:format("Terminating ~p in State ~p (Reason: ~p)~n",
[?MODULE, State, Reason]),
ok.
code_change(_OldVsn, StateName, LoopDat, _Extra) ->
{ok, StateName, LoopDat}.
handle_event(Event, State, LoopDat) ->
io:format("Unknown Event ~p in state ~p~n", [Event, State]),
{next_state, State, LoopDat}.
handle_info(Info, State, LoopDat) ->
io:format("Unknown Info ~p in state ~p~n", [Info, State]),
{next_state, State, LoopDat}.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% STATE "idle"
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
idle(start, LoopDat) ->
% send sio
send_to_txc(si_o, LoopDat),
% start timer
T2tout = LoopDat#iac_state.t2_timeout,
{ok, T2} = timer:apply_after(T2tout, gen_fsm, send_event,
[self(), {timer_expired, t2}]),
{next_state, not_aligned, LoopDat#iac_state{t2 = T2}};
idle(emergency, LoopDat) ->
% mark emergency
{next_state, idle, LoopDat#iac_state{emergency = 1}}.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% STATE "not aligned"
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
not_aligned(stop, LoopDat) ->
% stop T2
timer:cancel(LoopDat#iac_state.t2),
% cancel emergency
{next_state, idle, LoopDat#iac_state{emergency=0}};
not_aligned(si_e, LoopDat) ->
% stop T2
timer:cancel(LoopDat#iac_state.t2),
T4tout = LoopDat#iac_state.t4_timeout_pe,
% send SIE or SIN
case LoopDat#iac_state.emergency of
0 ->
Send = si_n;
_ ->
Send = si_e
end,
send_to_txc(Send, LoopDat),
% start T3
T3tout = LoopDat#iac_state.t3_timeout,
{ok, T3} = timer:apply_after(T3tout, gen_fsm, send_event,
[self(), {timer_expired, t3}]),
{next_state, aligned, LoopDat#iac_state{t3 = T3, t2 = undefined, t4_timeout = T4tout}};
not_aligned(What, LoopDat) when What == si_o; What == si_n ->
% stop T2
timer:cancel(LoopDat#iac_state.t2),
% send SIE or SIN
case LoopDat#iac_state.emergency of
0 ->
T4tout = LoopDat#iac_state.t4_timeout_pn,
Send = si_n;
_ ->
T4tout = LoopDat#iac_state.t4_timeout_pe,
Send = si_e
end,
send_to_txc(Send, LoopDat),
T3tout = LoopDat#iac_state.t3_timeout,
{ok, T3} = timer:apply_after(T3tout, gen_fsm, send_event,
[self(), {timer_expired, t3}]),
{next_state, aligned, LoopDat#iac_state{t3 = T3, t2 = undefined, t4_timeout = T4tout}};
not_aligned(emergency, LoopDat) ->
% mark emergency
{next_state, not_aligned, LoopDat#iac_state{emergency=1}};
not_aligned(si_os, LoopDat) ->
% ignore SIOS in this state, as some implementations (notably
% yate) seem to send it in violation of the spec
{next_state, not_aligned, LoopDat};
not_aligned({timer_expired, t2}, LoopDat) ->
% send 'alignment not possible' to LSC
send_to_lsc(alignment_not_possible, LoopDat),
% stop emergency
{next_state, idle, LoopDat#iac_state{emergency=0}}.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% STATE "aligned"
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
aligned(What, LoopDat) when What == si_n; What == si_e ->
case What of
si_e ->
% set T4 to Pe
T4tout = LoopDat#iac_state.t4_timeout_pe;
_ ->
T4tout = LoopDat#iac_state.t4_timeout_pn
end,
% stop T3
timer:cancel(LoopDat#iac_state.t3),
ToutPE = LoopDat#iac_state.t4_timeout_pe,
case T4tout of
ToutPE ->
% set i to ie IAC->AERM
send_to_aerm(set_i_to_ie, LoopDat);
_ ->
ok
end,
% send Start to AERM
send_to_aerm(start, LoopDat),
% start T4
{ok, T4} = timer:apply_after(T4tout, gen_fsm, send_event,
[self(), {timer_expired, t4}]),
% Cp := 0
% cancel further proving?
LoopDat2 = LoopDat#iac_state{t4 = T4, t4_timeout = T4tout,
cp = 0, further_prov = 0},
{next_state, proving, LoopDat2};
aligned(emergency, LoopDat) ->
% Send SIE
send_to_txc(si_e, LoopDat),
T4tout = LoopDat#iac_state.t4_timeout_pe,
{next_State, aligned, LoopDat#iac_state{t4_timeout = T4tout}};
aligned(si_os, LoopDat) ->
% Send alignment not possible
send_to_lsc(alignment_not_possible, LoopDat),
% stop T3
timer:cancel(LoopDat#iac_state.t3),
{next_state, idle, LoopDat#iac_state{emergency=0, t3=undefined}};
aligned(stop, LoopDat) ->
% Stop T3
timer:cancel(LoopDat#iac_state.t3),
% cancel Emergency
{next_state, idle, LoopDat#iac_state{emergency=0, t3=undefined}};
aligned({timer_expired, t3}, LoopDat) ->
% Send alignment not possible
send_to_lsc(alignment_not_possible, LoopDat),
% cancel emergency
{next_state, idle, LoopDat#iac_state{emergency=0}}.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% STATE "proving"
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
fig9_4(LoopDat) ->
% send Stop to AERM
send_to_aerm(stop, LoopDat),
% cancel emergency
{next_state, idle, LoopDat#iac_state{emergency=0}}.
fig9_5(LoopDat) ->
% send Start to AERM
send_to_aerm(start, LoopDat),
% cancel further proving
% start T4
T4tout = LoopDat#iac_state.t4_timeout,
{ok, T4} = timer:apply_after(T4tout, gen_fsm, send_event,
[self(), {timer_expired, t4}]),
{next_state, proving, LoopDat#iac_state{t4=T4, further_prov=0}}.
prov_emerg_or_sie(LoopDat) ->
% stop T4
timer:cancel(LoopDat#iac_state.t4),
% Set T4 to Pe
T4tout = LoopDat#iac_state.t4_timeout_pe,
% Send stop to AERM
send_to_aerm(stop, LoopDat),
% Send 'set ti to tie' to AERM
send_to_aerm(set_ti_to_tie, LoopDat),
fig9_5(LoopDat#iac_state{t4_timeout=T4tout, t4=undefined}).
proving(expires, LoopDat) ->
% alignment complete
{next_state, idle, LoopDat};
proving(si_e, LoopDat) ->
ToutPE = LoopDat#iac_state.t4_timeout_pe,
case LoopDat#iac_state.t4_timeout of
ToutPE ->
{next_state, proving, LoopDat};
_ ->
prov_emerg_or_sie(LoopDat)
end;
proving(emergency, LoopDat) ->
prov_emerg_or_sie(LoopDat);
proving(stop, LoopDat) ->
% stop T4
timer:cancel(LoopDat#iac_state.t4),
fig9_4(LoopDat);
proving(si_os, LoopDat) ->
% stop T4
timer:cancel(LoopDat#iac_state.t4),
% Send alignment not possible to LSC
send_to_lsc(alignment_not_possible, LoopDat),
fig9_4(LoopDat);
proving(high_err_rate, LoopDat) ->
% alignment not possible
{next_state, idle, LoopDat};
proving(sio, LoopDat) ->
% stop T4
timer:cancel(LoopDat#iac_state.t4),
% send Stop to AERM
send_to_aerm(stop, LoopDat),
% start T3
T3tout = LoopDat#iac_state.t3_timeout,
{ok, T3} = timer:apply_after(T3tout, gen_fsm, send_event,
[self(), {timer_expired, t3}]),
{next_state, aligned, LoopDat#iac_state{t3=T3, t4=undefined}};
proving(What, LoopDat) when What == correct_su; What == si_n ->
case LoopDat#iac_state.further_prov of
1 ->
% stop T4
timer:cancel(LoopDat#iac_state.t4),
fig9_5(LoopDat);
_ ->
{next_state, proving, LoopDat}
end;
proving({timer_expired, t4}, LoopDat) ->
% check if we are further proving, if yes, call fig9_5
case LoopDat#iac_state.further_prov of
1 ->
fig9_5(LoopDat);
_ ->
% send 'aligment complete' to LSC
send_to_lsc(alignment_complete, LoopDat),
fig9_4(LoopDat)
end;
proving(abort_proving, LoopDat) ->
% Cp := Cp + 1
Cp = LoopDat#iac_state.cp,
LoopDat2 = LoopDat#iac_state{cp = Cp + 1},
case Cp + 1 of
5 ->
% send 'alignment not possible' to LSC
send_to_lsc(alignment_not_possible, LoopDat),
% stop T4
timer:cancel(LoopDat#iac_state.t4),
fig9_4(LoopDat2);
_ ->
% mark further proving
{next_state, proving, LoopDat2#iac_state{further_prov=1}}
end.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% helper functions
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
send_to_lsc(What, #iac_state{lsc_pid = Lsc}) ->
gen_fsm:send_event(Lsc, What).
send_to_aerm(What, #iac_state{aerm_pid = Aerm}) ->
Aerm ! {iac_aerm, What}.
send_to_txc(What, #iac_state{txc_pid = Txc}) ->
Txc ! {iac_txc, What}.
|
