%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2010-2017. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
%%
%% This module implements (as a process) the state machine documented
%% in Appendix A of RFC 3539.
%%
-module(diameter_watchdog).
-behaviour(gen_server).
%% towards diameter_service
-export([start/2]).
%% gen_server callbacks
-export([init/1,
handle_call/3,
handle_cast/2,
handle_info/2,
terminate/2,
code_change/3]).
%% diameter_watchdog_sup callback
-export([start_link/1]).
-include_lib("diameter/include/diameter.hrl").
-include("diameter_internal.hrl").
-define(DEFAULT_TW_INIT, 30000). %% RFC 3539 ch 3.4.1
-define(NOMASK, {0,32}). %% default sequence mask
-define(BASE, ?DIAMETER_DICT_COMMON).
-define(IS_NATURAL(N), (is_integer(N) andalso 0 =< N)).
-record(watchdog,
{%% PCB - Peer Control Block; see RFC 3539, Appendix A
status = initial :: initial | okay | suspect | down | reopen,
pending = false :: boolean(), %% DWA
tw :: 6000..16#FFFFFFFF | {module(), atom(), list()},
%% {M,F,A} -> integer() >= 0
num_dwa = 0 :: -1 | non_neg_integer(),
%% number of DWAs received in reopen,
%% or number of timeouts before okay -> suspect
%% end PCB
parent = self() :: pid(), %% service process
transport :: pid() | undefined, %% peer_fsm process
tref :: reference() %% reference for current watchdog timer
| integer() %% monotonic time
| undefined,
dictionary :: module(), %% common dictionary
receive_data :: term(), %% term passed with incoming message
config :: #{sequence := diameter:sequence(), %% mask
restrict_connections := diameter:restriction(),
restrict := boolean(),
suspect := non_neg_integer(), %% OKAY -> SUSPECT
okay := non_neg_integer()}, %% REOPEN -> OKAY
codec :: #{decode_format := none,
string_decode := false,
strict_arities => diameter:strict_arities(),
strict_mbit := boolean(),
rfc := 3588 | 6733,
ordered_encode := false},
shutdown = false :: boolean()}).
%% ---------------------------------------------------------------------------
%% start/2
%%
%% Start a monitor before the watchdog is allowed to proceed to ensure
%% that a failed capabilities exchange produces the desired exit
%% reason.
%% ---------------------------------------------------------------------------
-spec start(Type, {[Opt], SvcOpts, RecvData, #diameter_service{}})
-> {reference(), pid()}
when Type :: {connect|accept, diameter:transport_ref()},
Opt :: diameter:transport_opt(),
SvcOpts :: map(),
RecvData :: term().
start({_,_} = Type, T) ->
Ack = make_ref(),
{ok, Pid} = diameter_watchdog_sup:start_child({Ack, Type, self(), T}),
try
{monitor(process, Pid), Pid}
after
send(Pid, Ack)
end.
start_link(T) ->
{ok, _} = proc_lib:start_link(?MODULE,
init,
[T],
infinity,
diameter_lib:spawn_opts(server, [])).
%% ===========================================================================
%% ===========================================================================
%% init/1
init(T) ->
proc_lib:init_ack({ok, self()}),
gen_server:enter_loop(?MODULE, [], i(T)).
i({Ack, T, Pid, {Opts,
#{restrict_connections := Restrict}
= SvcOpts0,
RecvData,
#diameter_service{applications = Apps,
capabilities = Caps}
= Svc}}) ->
monitor(process, Pid),
wait(Ack, Pid),
Dict0 = common_dictionary(Apps),
SvcOpts = SvcOpts0#{rfc => rfc(Dict0)},
putr(restart, {T, Opts, Svc, SvcOpts}), %% save seeing it in trace
putr(dwr, dwr(Caps)), %%
Nodes = restrict_nodes(Restrict),
#watchdog{parent = Pid,
transport = start(T, Opts, SvcOpts, Nodes, Dict0, Svc),
tw = proplists:get_value(watchdog_timer,
Opts,
?DEFAULT_TW_INIT),
receive_data = RecvData,
dictionary = Dict0,
config = maps:with([sequence,
restrict_connections,
restrict,
suspect,
okay],
config(SvcOpts#{restrict => restrict(Nodes),
suspect => 1,
okay => 3},
Opts)),
codec = maps:with([decode_format,
strict_arities,
strict_mbit,
string_decode,
rfc,
ordered_encode],
SvcOpts#{decode_format := none,
string_decode := false,
ordered_encode => false})}.
wait(Ref, Pid) ->
receive
Ref ->
ok;
{'DOWN', _, process, Pid, _} = D ->
exit({shutdown, D})
end.
%% Regard anything but the generated RFC 3588 dictionary as modern.
%% This affects the interpretation of defaults during the decode
%% of values of type DiameterURI, this having changed from RFC 3588.
%% (So much for backwards compatibility.)
rfc(?BASE) ->
3588;
rfc(_) ->
6733.
%% config/2
%%
%% Could also configure counts for SUSPECT to DOWN and REOPEN to DOWN,
%% but don't.
config(Map, Opts) ->
Config = proplists:get_value(watchdog_config, Opts, []),
lists:foldl(fun cfg/2, Map, Config).
cfg({suspect, N}, Map)
when ?IS_NATURAL(N) ->
Map#{suspect := N};
cfg({okay, N}, Map)
when ?IS_NATURAL(N) ->
Map#{okay := N}.
%% start/6
start(T, Opts, SvcOpts, Nodes, Dict0, Svc) ->
{_MRef, Pid}
= diameter_peer_fsm:start(T, Opts, {SvcOpts, Nodes, Dict0, Svc}),
Pid.
%% common_dictionary/1
%%
%% Determine the dictionary of the Diameter common application with
%% Application Id 0. Fail on config errors.
common_dictionary(Apps) ->
case
orddict:fold(fun dict0/3,
false,
lists:foldl(fun(#diameter_app{dictionary = M}, D) ->
orddict:append(M:id(), M, D)
end,
orddict:new(),
Apps))
of
{value, Mod} ->
Mod;
false ->
%% A transport should configure a common dictionary but
%% don't require it. Not configuring a common dictionary
%% means a user won't be able either send of receive
%% messages in the common dictionary: incoming request
%% will be answered with 3007 and outgoing requests cannot
%% be sent. The dictionary returned here is only used for
%% messages diameter sends and receives: CER/CEA, DPR/DPA
%% and DWR/DWA.
?BASE
end.
%% Each application should be represented by a single dictionary.
dict0(Id, [_,_|_] = Ms, _) ->
config_error({multiple_dictionaries, Ms, {application_id, Id}});
%% An explicit common dictionary.
dict0(?APP_ID_COMMON, [Mod], _) ->
{value, Mod};
%% A pure relay, in which case the common application is implicit.
%% This uses the fact that the common application will already have
%% been folded.
dict0(?APP_ID_RELAY, _, false) ->
{value, ?BASE};
dict0(_, _, Acc) ->
Acc.
config_error(T) ->
exit({shutdown, {configuration_error, T}}).
%% handle_call/3
handle_call(_, _, State) ->
{reply, nok, State}.
%% handle_cast/2
handle_cast(_, State) ->
{noreply, State}.
%% handle_info/2
handle_info(T, #watchdog{} = State) ->
case transition(T, State) of
ok ->
{noreply, State};
#watchdog{} = S ->
close(T, State), %% service expects 'close' message
event(T, State, S), %% before 'watchdog'
{noreply, S};
stop ->
?LOG(stop, truncate(T)),
event(T, State, State#watchdog{status = down}),
{stop, {shutdown, T}, State}
end.
truncate({'DOWN' = T, _, process, Pid, _}) ->
{T, Pid};
truncate(T) ->
T.
close({'DOWN', _, process, TPid, {shutdown, Reason}},
#watchdog{transport = TPid,
parent = Pid}) ->
send(Pid, {close, self(), Reason});
close(_, _) ->
ok.
event(_,
#watchdog{status = From, transport = F},
#watchdog{status = To, transport = T})
when F == undefined, T == undefined; %% transport not started
From == initial, To == down; %% never really left INITIAL
From == To -> %% no state transition
ok;
%% Note that there is no INITIAL -> DOWN transition in RFC 3539: ours
%% is just a consequence of stop.
event(Msg,
#watchdog{status = From, transport = F, parent = Pid},
#watchdog{status = To, transport = T}) ->
TPid = tpid(F,T),
E = {[TPid | data(Msg, TPid, From, To)], From, To},
send(Pid, {watchdog, self(), E}),
?LOG(transition, {From, To}).
data(Msg, TPid, reopen, okay) ->
{recv, TPid, _, 'DWA', _Pkt} = Msg, %% assert
{TPid, T} = eraser(open),
[T];
data({open, TPid, _Hosts, T}, TPid, _From, To)
when To == okay;
To == reopen ->
[T];
data(_, _, _, _) ->
[].
tpid(_, Pid)
when is_pid(Pid) ->
Pid;
tpid(Pid, _) ->
Pid.
%% send/2
send(Pid, T) ->
Pid ! T.
%% terminate/2
terminate(_, _) ->
ok.
%% code_change/3
code_change(_, State, _) ->
{ok, State}.
%% ===========================================================================
%% ===========================================================================
%% transition/2
%%
%% The state transitions documented here are extracted from RFC 3539,
%% the commentary is ours.
%% Service is telling the watchdog of an accepting transport to die
%% following transport death in state INITIAL, or after connect_timer
%% expiry; or another watchdog is saying the same after reestablishing
%% a connection previously had by this one.
transition(close, #watchdog{}) ->
{accept, _} = role(), %% assert
stop;
%% Service is asking for the peer to be taken down gracefully.
transition({shutdown, Pid, _}, #watchdog{parent = Pid,
transport = undefined}) ->
stop;
transition({shutdown = T, Pid, Reason}, #watchdog{parent = Pid,
transport = TPid}
= S) ->
send(TPid, {T, self(), Reason}),
S#watchdog{shutdown = true};
%% Transport is telling us that DPA has been sent in response to DPR,
%% or that DPR has been explicitly sent: transport death should lead
%% to ours.
transition({'DPR', TPid}, #watchdog{transport = TPid} = S) ->
S#watchdog{shutdown = true};
%% Parent process has died,
transition({'DOWN', _, process, Pid, _Reason},
#watchdog{parent = Pid}) ->
stop;
%% Transport has accepted a connection.
transition({accepted = T, TPid}, #watchdog{transport = TPid,
parent = Pid}) ->
send(Pid, {T, self(), TPid}),
ok;
%% STATE Event Actions New State
%% ===== ------ ------- ----------
%% INITIAL Connection up SetWatchdog() OKAY
%% By construction, the watchdog timer isn't set until we move into
%% state okay as the result of the Peer State Machine reaching the
%% Open state.
%%
%% If we're accepting then we may be resuming a connection that went
%% down in another watchdog process, in which case this is the
%% transition below, from down to reopen. That is, it's not until we
%% know the identity of the peer (ie. now) that we know that we're in
%% state down rather than initial.
transition({open, TPid, Hosts, _} = Open,
#watchdog{transport = TPid,
status = initial,
config = #{restrict := R,
suspect := OS}}
= S) ->
case okay(role(), Hosts, R) of
okay ->
set_watchdog(S#watchdog{status = okay,
num_dwa = OS});
reopen ->
transition(Open, S#watchdog{status = down})
end;
%% DOWN Connection up NumDWA = 0
%% SendWatchdog()
%% SetWatchdog()
%% Pending = TRUE REOPEN
transition({open = Key, TPid, _Hosts, T},
#watchdog{transport = TPid,
status = down,
config = #{suspect := OS,
okay := RO}}
= S) ->
case RO of
0 -> %% non-standard: skip REOPEN
set_watchdog(S#watchdog{status = okay,
num_dwa = OS});
_ ->
%% Store the info we need to notify the parent to reopen
%% the connection after the requisite DWA's are received,
%% at which time we eraser(open).
putr(Key, {TPid, T}),
set_watchdog(send_watchdog(S#watchdog{status = reopen,
num_dwa = 0}))
end;
%% OKAY Connection down CloseConnection()
%% Failover()
%% SetWatchdog() DOWN
%% SUSPECT Connection down CloseConnection()
%% SetWatchdog() DOWN
%% REOPEN Connection down CloseConnection()
%% SetWatchdog() DOWN
%% Transport has died after DPA or service requested termination ...
transition({'DOWN', _, process, TPid, _Reason},
#watchdog{transport = TPid,
shutdown = true}) ->
stop;
%% ... or not.
transition({'DOWN', _, process, TPid, _Reason} = D,
#watchdog{transport = TPid,
status = T,
config = #{restrict := R}}
= S0) ->
S = S0#watchdog{pending = false,
transport = undefined},
{M,_} = role(),
%% Close an accepting watchdog immediately if there's no
%% restriction on the number of connections to the same peer: the
%% state machine never enters state REOPEN in this case.
if T == initial;
M == accept, not R ->
close(D, S0),
stop;
true ->
set_watchdog(S#watchdog{status = down})
end;
%% Incoming message.
transition({recv, TPid, Route, Name, Pkt},
#watchdog{transport = TPid}
= S) ->
try incoming(Route, Name, Pkt, S) of
#watchdog{dictionary = Dict0, receive_data = T} = NS ->
diameter_traffic:receive_message(TPid, Route, Pkt, Dict0, T),
NS
catch
#watchdog{} = NS ->
NS
end;
%% Current watchdog has timed out.
transition({timeout, TRef, tw}, #watchdog{tref = TRef} = S) ->
set_watchdog(0, timeout(S));
%% Message has arrived since the timer was started: subtract time
%% already elapsed from new timer.
transition({timeout, _, tw}, #watchdog{tref = T0} = S) ->
set_watchdog(diameter_lib:micro_diff(T0) div 1000, S);
%% State query.
transition({state, Pid}, #watchdog{status = S}) ->
send(Pid, {self(), S}),
ok.
%% ===========================================================================
putr(Key, Val) ->
put({?MODULE, Key}, Val).
getr(Key) ->
get({?MODULE, Key}).
eraser(Key) ->
erase({?MODULE, Key}).
%% encode/4
encode(dwr = M, Dict0, Opts, Mask) ->
Msg = getr(M),
Seq = diameter_session:sequence(Mask),
Hdr = #diameter_header{version = ?DIAMETER_VERSION,
end_to_end_id = Seq,
hop_by_hop_id = Seq},
Pkt = #diameter_packet{header = Hdr,
msg = Msg},
diameter_codec:encode(Dict0, Opts, Pkt);
encode(dwa, Dict0, Opts, #diameter_packet{header = H, transport_data = TD}
= ReqPkt) ->
AnsPkt = #diameter_packet{header
= H#diameter_header{is_request = false,
is_error = undefined,
is_retransmitted = false},
msg = dwa(ReqPkt),
transport_data = TD},
diameter_codec:encode(Dict0, Opts, AnsPkt).
%% okay/3
okay({accept, Ref}, Hosts, Restrict) ->
T = {?MODULE, connection, Ref, Hosts},
diameter_reg:add(T),
if Restrict ->
okay(diameter_reg:match(T));
true ->
okay
end;
%% Register before matching so that at least one of two registering
%% processes will match the other.
okay({connect, _}, _, _) ->
okay.
%% okay/2
%% The peer hasn't been connected recently ...
okay([{_,P}]) ->
P = self(), %% assert
okay;
%% ... or it has.
okay(C) ->
[_|_] = [send(P, close) || {_,P} <- C, self() /= P],
reopen.
%% role/0
role() ->
element(1, getr(restart)).
%% set_watchdog/1
%% Timer not yet set.
set_watchdog(#watchdog{tref = undefined} = S) ->
set_watchdog(0, S);
%% Timer already set: start at new one only at expiry.
set_watchdog(#watchdog{} = S) ->
S#watchdog{tref = diameter_lib:now()}.
%% set_watchdog/2
set_watchdog(_, stop = No) ->
No;
set_watchdog(Ms, #watchdog{tw = TwInit} = S) ->
S#watchdog{tref = erlang:start_timer(tw(TwInit, Ms), self(), tw)}.
%% A callback could return anything, so ensure the result isn't
%% negative. Don't prevent abuse, even though the smallest valid
%% timeout is 4000.
tw(TwInit, Ms) ->
max(tw(TwInit) - Ms, 0).
tw(T)
when is_integer(T), T >= 6000 ->
T - 2000 + (rand:uniform(4001) - 1); %% RFC3539 jitter of +/- 2 sec.
tw({M,F,A}) ->
apply(M,F,A).
%% send_watchdog/1
send_watchdog(#watchdog{pending = false,
transport = TPid,
dictionary = Dict0,
config = #{sequence := Mask},
codec = Opts}
= S) ->
#diameter_packet{bin = Bin} = EPkt = encode(dwr, Dict0, Opts, Mask),
diameter_traffic:incr(send, EPkt, TPid, Dict0),
send(TPid, {send, Bin}),
?LOG(send, 'DWR'),
S#watchdog{pending = true}.
%% Don't count encode errors since we don't expect any on DWR/DWA.
%% incoming/4
incoming(Route, Name, Pkt, S) ->
try rcv(Name, S) of
NS -> rcv(Name, Pkt, NS)
catch
#watchdog{transport = TPid} = NS when Route -> %% incoming request
send(TPid, {send, false}), %% requiring ack
throw(NS)
end.
%% rcv/3
rcv('DWR', Pkt, #watchdog{transport = TPid,
dictionary = Dict0,
codec = Opts}
= S) ->
?LOG(recv, 'DWR'),
DPkt = diameter_codec:decode(Dict0, Opts, Pkt),
diameter_traffic:incr(recv, DPkt, TPid, Dict0),
diameter_traffic:incr_error(recv, DPkt, TPid, Dict0),
#diameter_packet{header = H,
transport_data = T,
bin = Bin}
= EPkt
= encode(dwa, Dict0, Opts, Pkt),
diameter_traffic:incr(send, EPkt, TPid, Dict0),
diameter_traffic:incr_rc(send, EPkt, TPid, Dict0),
%% Strip potentially large message terms.
send(TPid, {send, #diameter_packet{header = H,
transport_data = T,
bin = Bin}}),
?LOG(send, 'DWA'),
throw(S);
rcv('DWA', Pkt, #watchdog{transport = TPid,
dictionary = Dict0,
codec = Opts}
= S) ->
?LOG(recv, 'DWA'),
diameter_traffic:incr(recv, Pkt, TPid, Dict0),
diameter_traffic:incr_rc(recv,
diameter_codec:decode(Dict0, Opts, Pkt),
TPid,
Dict0),
throw(S);
rcv(N, _, S)
when N == 'CER';
N == 'CEA';
N == 'DPR' ->
throw(S);
%% DPR can be sent explicitly with diameter:call/4. Only the
%% corresponding DPAs arrive here.
rcv(_, _, S)->
S.
%% rcv/2
%%
%% The lack of Hop-by-Hop and End-to-End Identifiers checks in a
%% received DWA is intentional. The purpose of the message is to
%% demonstrate life but a peer that consistently bungles it by sending
%% the wrong identifiers causes the connection to toggle between OPEN
%% and SUSPECT, with failover and failback as result, despite there
%% being no real problem with connectivity. Thus, relax and accept any
%% incoming DWA as being in response to an outgoing DWR.
%% INITIAL Receive DWA Pending = FALSE
%% Throwaway() INITIAL
%% INITIAL Receive non-DWA Throwaway() INITIAL
rcv('DWA', #watchdog{status = initial} = S) ->
throw(S#watchdog{pending = false});
rcv(_, #watchdog{status = initial} = S) ->
throw(S);
%% DOWN Receive DWA Pending = FALSE
%% Throwaway() DOWN
%% DOWN Receive non-DWA Throwaway() DOWN
rcv('DWA', #watchdog{status = down} = S) ->
throw(S#watchdog{pending = false});
rcv(_, #watchdog{status = down} = S) ->
throw(S);
%% OKAY Receive DWA Pending = FALSE
%% SetWatchdog() OKAY
%% OKAY Receive non-DWA SetWatchdog() OKAY
rcv('DWA', #watchdog{status = okay} = S) ->
set_watchdog(S#watchdog{pending = false});
rcv(_, #watchdog{status = okay} = S) ->
set_watchdog(S);
%% SUSPECT Receive DWA Pending = FALSE
%% Failback()
%% SetWatchdog() OKAY
%% SUSPECT Receive non-DWA Failback()
%% SetWatchdog() OKAY
rcv('DWA', #watchdog{status = suspect, config = #{suspect := OS}} = S) ->
set_watchdog(S#watchdog{status = okay,
num_dwa = OS,
pending = false});
rcv(_, #watchdog{status = suspect, config = #{suspect := OS}} = S) ->
set_watchdog(S#watchdog{status = okay,
num_dwa = OS});
%% REOPEN Receive DWA & Pending = FALSE
%% NumDWA == 2 NumDWA++
%% Failback() OKAY
rcv('DWA', #watchdog{status = reopen,
num_dwa = N,
config = #{suspect := OS,
okay := RO}}
= S)
when N+1 == RO ->
S#watchdog{status = okay,
num_dwa = OS,
pending = false};
%% REOPEN Receive DWA & Pending = FALSE
%% NumDWA < 2 NumDWA++ REOPEN
rcv('DWA', #watchdog{status = reopen,
num_dwa = N}
= S) ->
S#watchdog{num_dwa = N+1,
pending = false};
%% REOPEN Receive non-DWA Throwaway() REOPEN
rcv('DWR', #watchdog{status = reopen} = S) ->
S; %% ensure DWA: the RFC isn't explicit about answering
rcv(_, #watchdog{status = reopen} = S) ->
throw(S).
%% timeout/1
%%
%% The caller sets the watchdog on the return value.
%% OKAY Timer expires & SendWatchdog()
%% !Pending SetWatchdog()
%% Pending = TRUE OKAY
%% REOPEN Timer expires & SendWatchdog()
%% !Pending SetWatchdog()
%% Pending = TRUE REOPEN
timeout(#watchdog{status = T,
pending = false}
= S)
when T == okay;
T == reopen ->
send_watchdog(S);
%% OKAY Timer expires & Failover()
%% Pending SetWatchdog() SUSPECT
timeout(#watchdog{status = okay,
pending = true,
num_dwa = N}
= S) ->
case N of
1 ->
S#watchdog{status = suspect};
0 -> %% non-standard: never move to suspect
S;
N -> %% non-standard: more timeouts before moving
S#watchdog{num_dwa = N-1}
end;
%% SUSPECT Timer expires CloseConnection()
%% SetWatchdog() DOWN
%% REOPEN Timer expires & CloseConnection()
%% Pending & SetWatchdog()
%% NumDWA < 0 DOWN
timeout(#watchdog{status = T,
pending = P,
num_dwa = N,
transport = TPid}
= S)
when T == suspect;
T == reopen, P, N < 0 ->
exit(TPid, {shutdown, watchdog_timeout}),
S#watchdog{status = down};
%% REOPEN Timer expires & NumDWA = -1
%% Pending & SetWatchdog()
%% NumDWA >= 0 REOPEN
timeout(#watchdog{status = reopen,
pending = true,
num_dwa = N}
= S)
when 0 =< N ->
S#watchdog{num_dwa = -1};
%% DOWN Timer expires AttemptOpen()
%% SetWatchdog() DOWN
%% INITIAL Timer expires AttemptOpen()
%% SetWatchdog() INITIAL
%% RFC 3539, 3.4.1:
%%
%% [5] While the connection is in the closed state, the AAA client MUST
%% NOT attempt to send further watchdog messages on the connection.
%% However, after the connection is closed, the AAA client continues
%% to periodically attempt to reopen the connection.
%%
%% The AAA client SHOULD wait for the transport layer to report
%% connection failure before attempting again, but MAY choose to
%% bound this wait time by the watchdog interval, Tw.
%% Don't bound, restarting the peer process only when the previous
%% process has died. We only need to handle state down since we start
%% the first watchdog when transitioning out of initial.
timeout(#watchdog{status = T} = S)
when T == initial;
T == down ->
restart(S).
%% restart/1
restart(#watchdog{transport = undefined} = S) ->
restart(getr(restart), S);
restart(S) -> %% reconnect has won race with timeout
S.
%% restart/2
%%
%% Only restart the transport in the connecting case. For an accepting
%% transport, there's no guarantee that an accepted connection in a
%% restarted transport if from the peer we've lost contact with so
%% have to be prepared for another watchdog to handle it. This is what
%% the diameter_reg registration in this module is for: the peer
%% connection is registered when leaving state initial and this is
%% used by a new accepting watchdog to realize that it's actually in
%% state down rather then initial when receiving notification of an
%% open connection.
restart({{connect, _} = T, Opts, Svc, SvcOpts},
#watchdog{parent = Pid,
config = #{restrict_connections := R}
= M,
dictionary = Dict0}
= S) ->
send(Pid, {reconnect, self()}),
Nodes = restrict_nodes(R),
S#watchdog{transport = start(T, Opts, SvcOpts, Nodes, Dict0, Svc),
config = M#{restrict => restrict(Nodes)}};
%% No restriction on the number of connections to the same peer: just
%% die. Note that a state machine never enters state REOPEN in this
%% case.
restart({{accept, _}, _, _, _}, #watchdog{config = #{restrict := false}}) ->
stop;
%% Otherwise hang around until told to die, either by the service or
%% by another watchdog.
restart({{accept, _}, _, _, _}, S) ->
S.
%% Don't currently use Opts/Svc in the accept case.
%% dwr/1
dwr(#diameter_caps{origin_host = OH,
origin_realm = OR,
origin_state_id = OSI}) ->
['DWR', {'Origin-Host', OH},
{'Origin-Realm', OR},
{'Origin-State-Id', OSI}].
%% dwa/1
dwa(#diameter_packet{header = H, errors = Es}) ->
{RC, FailedAVP} = diameter_peer_fsm:result_code(H, Es),
['DWA', {'Result-Code', RC}
| tl(getr(dwr)) ++ FailedAVP].
%% restrict_nodes/1
restrict_nodes(false) ->
[];
restrict_nodes(nodes) ->
[node() | nodes()];
restrict_nodes(node) ->
[node()];
restrict_nodes(Nodes)
when [] == Nodes;
is_atom(hd(Nodes)) ->
Nodes;
restrict_nodes(F) ->
diameter_lib:eval(F).
%% restrict/1
restrict(Nodes) ->
lists:member(node(), Nodes).
