diff options
Diffstat (limited to 'lib/diameter/src/base/diameter_peer_fsm.erl')
-rw-r--r-- | lib/diameter/src/base/diameter_peer_fsm.erl | 404 |
1 files changed, 227 insertions, 177 deletions
diff --git a/lib/diameter/src/base/diameter_peer_fsm.erl b/lib/diameter/src/base/diameter_peer_fsm.erl index 7ee1e5fe59..d99f11a697 100644 --- a/lib/diameter/src/base/diameter_peer_fsm.erl +++ b/lib/diameter/src/base/diameter_peer_fsm.erl @@ -128,7 +128,13 @@ %% outgoing DPR; boolean says whether or not %% the request was sent explicitly with %% diameter:call/4. + codec :: #{decode_format := diameter:decode_format(), + string_decode := boolean(), + strict_mbit := boolean(), + rfc := 3588 | 6733, + ordered_encode := false}, strict :: boolean(), + ack = false :: boolean(), length_errors :: exit | handle | discard, incoming_maxlen :: integer() | infinity}). @@ -159,10 +165,7 @@ %% # start/3 %% --------------------------------------------------------------------------- --spec start(T, [Opt], {[diameter:service_opt()], - [node()], - module(), - #diameter_service{}}) +-spec start(T, [Opt], {map(), [node()], module(), #diameter_service{}}) -> {reference(), pid()} when T :: {connect|accept, diameter:transport_ref()}, Opt :: diameter:transport_opt(). @@ -221,9 +224,10 @@ i({Ack, WPid, {M, Ref} = T, Opts, {SvcOpts, Nodes, Dict0, Svc}}) -> erlang:monitor(process, WPid), wait(Ack, WPid), diameter_stats:reg(Ref), - diameter_codec:setopts([{common_dictionary, Dict0} | SvcOpts]), - {_,_} = Mask = proplists:get_value(sequence, SvcOpts), - Maxlen = proplists:get_value(incoming_maxlen, SvcOpts, 16#FFFFFF), + + #{sequence := Mask, incoming_maxlen := Maxlen} + = SvcOpts, + {[Cs,Ds], Rest} = proplists:split(Opts, [capabilities_cb, disconnect_cb]), putr(?CB_KEY, {Ref, [F || {_,F} <- Cs]}), putr(?DPR_KEY, [F || {_, F} <- Ds]), @@ -234,8 +238,8 @@ i({Ack, WPid, {M, Ref} = T, Opts, {SvcOpts, Nodes, Dict0, Svc}}) -> proplists:get_value(dpa_timeout, Opts, ?DPA_TIMEOUT)}), Tmo = proplists:get_value(capx_timeout, Opts, ?CAPX_TIMEOUT), - Strictness = proplists:get_value(capx_strictness, Opts, true), - OnLengthErr = proplists:get_value(length_errors, Opts, exit), + Strict = proplists:get_value(strict_capx, Opts, true), + LengthErr = proplists:get_value(length_errors, Opts, exit), {TPid, Addrs} = start_transport(T, Rest, Svc), @@ -247,9 +251,15 @@ i({Ack, WPid, {M, Ref} = T, Opts, {SvcOpts, Nodes, Dict0, Svc}}) -> dictionary = Dict0, mode = M, service = svc(Svc, Addrs), - length_errors = OnLengthErr, - strict = Strictness, - incoming_maxlen = Maxlen}. + length_errors = LengthErr, + strict = Strict, + incoming_maxlen = Maxlen, + codec = maps:with([decode_format, + string_decode, + strict_mbit, + rfc, + ordered_encode], + SvcOpts#{ordered_encode => false})}. %% The transport returns its local ip addresses so that different %% transports on the same service can use different local addresses. %% The local addresses are put into Host-IP-Address avps here when @@ -359,7 +369,7 @@ handle_info(T, #state{} = State) -> %% Note that there's no guarantee that the service and transport %% capabilities are good enough to build a CER/CEA that can be -%% succesfully encoded. It's not checked at diameter:add_transport/2 +%% successfully encoded. It's not checked at diameter:add_transport/2 %% since this can be called before creating the service. %% terminate/2 @@ -442,9 +452,18 @@ transition({connection_timeout = T, TPid}, transition({connection_timeout, _}, _) -> ok; +%% Requests for acknowledgements to the transport. +transition({diameter, ack}, S) -> + S#state{ack = true}; + %% Incoming message from the transport. -transition({diameter, {recv, MsgT}}, S) -> - incoming(MsgT, S); +transition({diameter, {recv, Msg}}, S) -> + incoming(recv(Msg, S), S); + +%% Handler of an incoming request is telling of its existence. +transition({handler, Pid}, _) -> + put_route(Pid), + ok; %% Timeout when still in the same state ... transition({timeout = T, PS}, #state{state = PS}) -> @@ -458,7 +477,7 @@ transition({timeout, _}, _) -> transition({send, Msg}, S) -> outgoing(Msg, S); transition({send, Msg, Route}, S) -> - put_route(Route), + route_outgoing(Route), outgoing(Msg, S); %% Request for graceful shutdown at remove_transport, stop_service of @@ -487,12 +506,13 @@ transition({'DOWN', _, process, WPid, _}, transition({'DOWN', _, process, TPid, _}, #state{transport = TPid} = S) -> - start_next(S); + start_next(S#state{ack = false}); %% Transport has died after connection timeout, or handler process has %% died. -transition({'DOWN', _, process, Pid, _}, _) -> - erase_route(Pid), +transition({'DOWN', _, process, Pid, _}, #state{transport = TPid}) -> + is_reference(erase_route(Pid)) + andalso send(TPid, false), %% answer not forthcoming ok; %% State query. @@ -502,37 +522,62 @@ transition({state, Pid}, #state{state = S, transport = TPid}) -> %% Crash on anything unexpected. -%% put_route/1 -%% +%% route_outgoing/1 + %% Map identifiers in an outgoing request to be able to lookup the %% handler process when the answer is received. - -put_route({Pid, Ref, Seqs}) -> +route_outgoing({Pid, Ref, Seqs}) -> %% request MRef = monitor(process, Pid), put(Pid, Seqs), - put(Seqs, {Pid, Ref, MRef}). + put(Seqs, {Pid, Ref, MRef}); + +%% Remove a mapping made for an incoming request. +route_outgoing(Pid) + when is_pid(Pid) -> %% answer + MRef = erase_route(Pid), + undefined == MRef orelse demonitor(MRef). + +%% put_route/1 -%% get_route/1 +%% Monitor on a handler process for an incoming request. +put_route(Pid) -> + MRef = monitor(process, Pid), + put(Pid, MRef). + +%% get_route/3 -get_route(#diameter_packet{header = #diameter_header{is_request = false}} - = Pkt) -> +%% Incoming answer. +get_route(_, _, #diameter_packet{header = #diameter_header{is_request = false}} + = Pkt) -> Seqs = diameter_codec:sequence_numbers(Pkt), case erase(Seqs) of {Pid, Ref, MRef} -> demonitor(MRef), erase(Pid), {Pid, Ref, self()}; - undefined -> + undefined -> %% request unknown false end; -get_route(_) -> - false. +%% Requests answered here ... +get_route(_, N, _) + when N == 'CER'; + N == 'DPR' -> + false; + +%% ... or not. +get_route(Ack, _, _) -> + Ack. %% erase_route/1 erase_route(Pid) -> - erase(erase(Pid)). + case erase(Pid) of + {_,_} = Seqs -> + erase(Seqs); + T -> + T + end. %% capx/1 @@ -560,7 +605,8 @@ send_CER(#state{state = {'Wait-Conn-Ack', Tmo}, mode = {connect, Remote}, service = #diameter_service{capabilities = LCaps}, transport = TPid, - dictionary = Dict} + dictionary = Dict, + codec = Opts} = S) -> OH = LCaps#diameter_caps.origin_host, req_send_CER(OH, Remote) @@ -570,7 +616,7 @@ send_CER(#state{state = {'Wait-Conn-Ack', Tmo}, #diameter_packet{header = #diameter_header{end_to_end_id = Eid, hop_by_hop_id = Hid}} = Pkt - = encode(CER, Dict), + = encode(CER, Opts, Dict), incr(send, Pkt, Dict), send(TPid, Pkt), ?LOG(send, 'CER'), @@ -599,131 +645,126 @@ build_CER(#state{service = #diameter_service{capabilities = LCaps}, {ok, CER} = diameter_capx:build_CER(LCaps, Dict), CER. -%% encode/2 +%% encode/3 -encode(Rec, Dict) -> +encode(Rec, Opts, Dict) -> Seq = diameter_session:sequence({_,_} = getr(?SEQUENCE_KEY)), Hdr = #diameter_header{version = ?DIAMETER_VERSION, end_to_end_id = Seq, hop_by_hop_id = Seq}, - diameter_codec:encode(Dict, #diameter_packet{header = Hdr, - msg = Rec}). + diameter_codec:encode(Dict, Opts, #diameter_packet{header = Hdr, + msg = Rec}). %% incoming/2 -incoming({Msg, NPid}, S) -> - try recv(Msg, S) of - T -> - NPid ! {diameter, discard}, - T - catch - {?MODULE, Name, Pkt} -> - incoming(Name, Pkt, NPid, S) - end; +incoming(#diameter_header{is_request = R}, #state{transport = TPid, + ack = Ack}) -> + R andalso Ack andalso send(TPid, false), + ok; -incoming(Msg, S) -> - try - recv(Msg, S) - catch - {?MODULE, Name, Pkt} -> - incoming(Name, Pkt, false, S) - end. +incoming(<<_:32, 1:1, _/bits>>, #state{ack = true} = S) -> + send(S#state.transport, false), + ok; -%% incoming/4 +incoming(<<_/bits>>, _) -> + ok; -incoming(Name, Pkt, NPid, #state{parent = Pid} = S) -> - Pid ! {recv, self(), get_route(Pkt), Name, Pkt, NPid}, - rcv(Name, Pkt, S). +incoming(T, _) -> + T. %% recv/2 -recv(#diameter_packet{header = #diameter_header{} = Hdr} - = Pkt, - #state{dictionary = Dict0} - = S) -> - recv1(diameter_codec:msg_name(Dict0, Hdr), Pkt, S); - -recv(#diameter_packet{header = undefined, - bin = Bin} - = Pkt, - S) -> - recv(diameter_codec:decode_header(Bin), Pkt, S); +recv(#diameter_packet{bin = Bin} = Pkt, S) -> + recv(Bin, Pkt, S); recv(Bin, S) -> - recv(#diameter_packet{bin = Bin}, S). + recv(Bin, Bin, S). + +%% recv/3 -%% recv1/3 +recv(Bin, Msg, S) -> + recv(diameter_codec:decode_header(Bin), Bin, Msg, S). + +%% recv/4 + +recv(false, Bin, _, #state{length_errors = E}) -> + invalid(E, truncated_header, Bin), + Bin; + +recv(#diameter_header{length = Len} = H, Bin, Msg, #state{length_errors = E, + incoming_maxlen = M, + dictionary = Dict0} + = S) + when E == handle; + 0 == Len rem 4, bit_size(Bin) == 8*Len, size(Bin) =< M -> + recv1(diameter_codec:msg_name(Dict0, H), H, Msg, S); -recv1(_, - #diameter_packet{header = H, bin = Bin}, - #state{incoming_maxlen = M}) +recv(H, Bin, _, #state{incoming_maxlen = M}) when M < size(Bin) -> - invalid(false, incoming_maxlen_exceeded, {size(Bin), H}); + invalid(false, incoming_maxlen_exceeded, {size(Bin), H}), + H; + +recv(H, Bin, _, #state{length_errors = E}) -> + T = {size(Bin), bit_size(Bin) rem 8, H}, + invalid(E, message_length_mismatch, T), + H. + +%% recv1/4 %% Ignore anything but an expected CER/CEA if so configured. This is %% non-standard behaviour. -recv1(Name, _, #state{state = {'Wait-CEA', _, _}, - strict = false}) +recv1(Name, H, _, #state{state = {'Wait-CEA', _, _}, + strict = false}) when Name /= 'CEA' -> - ok; -recv1(Name, _, #state{state = recv_CER, - strict = false}) + H; +recv1(Name, H, _, #state{state = recv_CER, + strict = false}) when Name /= 'CER' -> - ok; + H; %% Incoming request after outgoing DPR: discard. Don't discard DPR, so %% both ends don't do so when sending simultaneously. -recv1(Name, - #diameter_packet{header = #diameter_header{is_request = true} = H}, - #state{dpr = {_,_,_}}) +recv1(Name, #diameter_header{is_request = true} = H, _, #state{dpr = {_,_,_}}) when Name /= 'DPR' -> - invalid(false, recv_after_outgoing_dpr, H); + invalid(false, recv_after_outgoing_dpr, H), + H; %% Incoming request after incoming DPR: discard. -recv1(_, - #diameter_packet{header = #diameter_header{is_request = true} = H}, - #state{dpr = true}) -> - invalid(false, recv_after_incoming_dpr, H); +recv1(_, #diameter_header{is_request = true} = H, _, #state{dpr = true}) -> + invalid(false, recv_after_incoming_dpr, H), + H; %% DPA with identifier mismatch, or in response to a DPR initiated by %% the service. -recv1('DPA' = N, - #diameter_packet{header = #diameter_header{hop_by_hop_id = Hid, - end_to_end_id = Eid}} - = Pkt, - #state{dpr = {X,H,E}} +recv1('DPA' = Name, + #diameter_header{hop_by_hop_id = Hid, end_to_end_id = Eid} + = H, + Msg, + #state{dpr = {X,HI,EI}} = S) - when H /= Hid; - E /= Eid; + when HI /= Hid; + EI /= Eid; not X -> - rcv(N, Pkt, S); + Pkt = pkt(H, Msg), + handle(Name, Pkt, S); -%% Any other message with a header and no length errors: send to the -%% parent. -recv1(Name, Pkt, #state{}) -> - throw({?MODULE, Name, Pkt}). +%% Any other message with a header and no length errors. +recv1(Name, H, Msg, #state{parent = Pid, ack = Ack} = S) -> + Pkt = pkt(H, Msg), + Pid ! {recv, self(), get_route(Ack, Name, Pkt), Name, Pkt}, + handle(Name, Pkt, S). -%% recv/3 +%% pkt/2 -recv(#diameter_header{length = Len} - = H, - #diameter_packet{bin = Bin} - = Pkt, - #state{length_errors = E} - = S) - when E == handle; - 0 == Len rem 4, bit_size(Bin) == 8*Len -> - recv(Pkt#diameter_packet{header = H}, S); +pkt(H, Bin) + when is_binary(Bin) -> + #diameter_packet{header = H, + bin = Bin}; -recv(#diameter_header{} - = H, - #diameter_packet{bin = Bin}, - #state{length_errors = E}) -> - T = {size(Bin), bit_size(Bin) rem 8, H}, - invalid(E, message_length_mismatch, T); +pkt(H, Pkt) -> + Pkt#diameter_packet{header = H}. -recv(false, #diameter_packet{bin = Bin}, #state{length_errors = E}) -> - invalid(E, truncated_header, Bin). +%% invalid/3 %% Note that counters here only count discarded messages. invalid(E, Reason, T) -> @@ -732,67 +773,65 @@ invalid(E, Reason, T) -> ?LOG(Reason, T), ok. -%% rcv/3 +%% handle/3 %% Incoming CEA. -rcv('CEA' = N, - #diameter_packet{header = #diameter_header{end_to_end_id = Eid, - hop_by_hop_id = Hid}} - = Pkt, - #state{state = {'Wait-CEA', Hid, Eid}} - = S) -> +handle('CEA' = N, + #diameter_packet{header = #diameter_header{end_to_end_id = Eid, + hop_by_hop_id = Hid}} + = Pkt, + #state{state = {'Wait-CEA', Hid, Eid}} + = S) -> ?LOG(recv, N), handle_CEA(Pkt, S); %% Incoming CER -rcv('CER' = N, Pkt, #state{state = recv_CER} = S) -> +handle('CER' = N, Pkt, #state{state = recv_CER} = S) -> handle_request(N, Pkt, S); %% Anything but CER/CEA in a non-Open state is an error, as is %% CER/CEA in anything but recv_CER/Wait-CEA. -rcv(Name, _, #state{state = PS}) +handle(Name, _, #state{state = PS}) when PS /= 'Open'; Name == 'CER'; Name == 'CEA' -> {stop, {Name, PS}}; -rcv('DPR' = N, Pkt, S) -> +handle('DPR' = N, Pkt, S) -> handle_request(N, Pkt, S); %% DPA in response to DPR, with the expected identifiers. -rcv('DPA' = N, - #diameter_packet{header = #diameter_header{end_to_end_id = Eid, - hop_by_hop_id = Hid} - = H} - = Pkt, +handle('DPA' = N, + #diameter_packet{header = #diameter_header{end_to_end_id = Eid, + hop_by_hop_id = Hid} + = H} + = Pkt, #state{dictionary = Dict0, transport = TPid, - dpr = {X, Hid, Eid}}) -> + dpr = {X, Hid, Eid}, + codec = Opts}) -> ?LOG(recv, N), X orelse begin %% Only count DPA in response to a DPR sent by the %% service: explicit DPR is counted in the same way %% as other explicitly sent requests. incr(recv, H, Dict0), - incr_rc(recv, diameter_codec:decode(Dict0, Pkt), Dict0) + {_, RecPkt} = decode(Dict0, Opts, Pkt), + incr_rc(recv, RecPkt, Dict0) end, diameter_peer:close(TPid), {stop, N}; -%% Ignore anything else, an unsolicited DPA in particular. Note that -%% dpa_timeout deals with the case in which the peer sends the wrong -%% identifiers in DPA. -rcv(N, #diameter_packet{header = H}, _) - when N == 'CER'; - N == 'CEA'; - N == 'DPR'; - N == 'DPA' -> +%% Ignore an unsolicited DPA in particular. Note that dpa_timeout +%% deals with the case in which the peer sends the wrong identifiers +%% in DPA. +handle('DPA' = N, #diameter_packet{header = H}, _) -> ?LOG(ignored, N), %% Note that these aren't counted in the normal recv counter. diameter_stats:incr({diameter_codec:msg_id(H), recv, ignored}), ok; -rcv(_, _, _) -> +handle(_, _, _) -> ok. %% incr/3 @@ -839,7 +878,7 @@ outgoing(#diameter_packet{header = #diameter_header{application_id = 0, invalid(false, dpr_after_dpr, H) %% DPR sent: discard end; -%% Explict CER or DWR: discard. These are sent by us. +%% Explicit CER or DWR: discard. These are sent by us. outgoing(#diameter_packet{header = #diameter_header{application_id = 0, cmd_code = C, is_request = true} @@ -875,22 +914,37 @@ header(Bin) -> %% DWR %% Incoming CER or DPR. handle_request(Name, - #diameter_packet{header = H} = Pkt, - #state{dictionary = Dict0} = S) -> + #diameter_packet{header = H} + = Pkt, + #state{dictionary = Dict0, + codec = Opts} + = S) -> ?LOG(recv, Name), incr(recv, H, Dict0), - send_answer(Name, diameter_codec:decode(Dict0, Pkt), S). + send_answer(Name, decode(Dict0, Opts, Pkt), S). + +%% decode/3 +%% +%% Decode the message as record for diameter_capx, and in the +%% configured format for events. + +decode(Dict0, Opts, Pkt) -> + {diameter_codec:decode(Dict0, Opts, Pkt), + diameter_codec:decode(Dict0, Opts#{decode_format := record}, Pkt)}. %% send_answer/3 -send_answer(Type, ReqPkt, #state{transport = TPid, dictionary = Dict} = S) -> - incr_error(recv, ReqPkt, Dict), +send_answer(Type, {DecPkt, RecPkt}, #state{transport = TPid, + dictionary = Dict, + codec = Opts} + = S) -> + incr_error(recv, RecPkt, Dict), #diameter_packet{header = H, transport_data = TD} - = ReqPkt, + = RecPkt, - {Msg, PostF} = build_answer(Type, ReqPkt, S), + {Msg, PostF} = build_answer(Type, DecPkt, RecPkt, S), %% An answer message clears the R and T flags and retains the P %% flag. The E flag is set at encode. @@ -902,7 +956,7 @@ send_answer(Type, ReqPkt, #state{transport = TPid, dictionary = Dict} = S) -> msg = Msg, transport_data = TD}, - AnsPkt = diameter_codec:encode(Dict, Pkt), + AnsPkt = diameter_codec:encode(Dict, Opts, Pkt), incr(send, AnsPkt, Dict), incr_rc(send, AnsPkt, Dict), @@ -918,19 +972,17 @@ eval([F|A], S) -> eval(T, _) -> close(T). -%% build_answer/3 +%% build_answer/4 build_answer('CER', + DecPkt, #diameter_packet{msg = CER, header = #diameter_header{version = ?DIAMETER_VERSION, is_error = false}, - errors = []} - = Pkt, + errors = []}, #state{dictionary = Dict0} = S) -> - diameter_codec:setopts([{string_decode, false}]), - {SupportedApps, RCaps, CEA} = recv_CER(CER, S), [RC, IS] = Dict0:'#get-'(['Result-Code', 'Inband-Security-Id'], CEA), @@ -946,25 +998,25 @@ build_answer('CER', orelse ?THROW(4003), %% DIAMETER_ELECTION_LOST caps_cb(Caps) of - N -> {cea(CEA, N, Dict0), [fun open/5, Pkt, + N -> {cea(CEA, N, Dict0), [fun open/5, DecPkt, SupportedApps, Caps, {accept, inband_security(IS)}]} catch ?FAILURE(Reason) -> - rejected(Reason, {'CER', Reason, Caps, Pkt}, S) + rejected(Reason, {'CER', Reason, Caps, DecPkt}, S) end; %% The error checks below are similar to those in diameter_traffic for %% other messages. Should factor out the commonality. build_answer(Type, + DecPkt, #diameter_packet{header = H, - errors = Es} - = Pkt, + errors = Es}, S) -> {RC, FailedAVP} = result_code(Type, H, Es), - {answer(Type, RC, FailedAVP, S), post(Type, RC, Pkt, S)}. + {answer(Type, RC, FailedAVP, S), post(Type, RC, DecPkt, S)}. inband_security([]) -> ?NO_INBAND_SECURITY; @@ -1131,19 +1183,15 @@ recv_CER(CER, #state{service = Svc, dictionary = Dict}) -> handle_CEA(#diameter_packet{header = H} = Pkt, #state{dictionary = Dict0, - service = #diameter_service{capabilities = LCaps}} + service = #diameter_service{capabilities = LCaps}, + codec = Opts} = S) -> incr(recv, H, Dict0), - #diameter_packet{} - = DPkt - = diameter_codec:decode(Dict0, Pkt), - - diameter_codec:setopts([{string_decode, false}]), - - RC = result_code(incr_rc(recv, DPkt, Dict0)), + {DecPkt, RecPkt} = decode(Dict0, Opts, Pkt), - {SApps, IS, RCaps} = recv_CEA(DPkt, S), + RC = result_code(incr_rc(recv, RecPkt, Dict0)), + {SApps, IS, RCaps} = recv_CEA(RecPkt, S), #diameter_caps{origin_host = {OH, DH}} = Caps @@ -1166,9 +1214,9 @@ handle_CEA(#diameter_packet{header = H} orelse ?THROW(election_lost), caps_cb(Caps) of - _ -> open(DPkt, SApps, Caps, {connect, hd([_] = IS)}, S) + _ -> open(DecPkt, SApps, Caps, {connect, hd([_] = IS)}, S) catch - ?FAILURE(Reason) -> close({'CEA', Reason, Caps, DPkt}) + ?FAILURE(Reason) -> close({'CEA', Reason, Caps, DecPkt}) end. %% Check more than the result code since the peer could send success %% regardless. If not 2001 then a peer_up callback could do anything @@ -1330,8 +1378,9 @@ dpr([], [Reason | _], S) -> -record(opts, {cause, timeout}). -send_dpr(Reason, Opts, #state{dictionary = Dict, - service = #diameter_service{capabilities = Caps}} +send_dpr(Reason, DprOpts, #state{dictionary = Dict, + service = #diameter_service{capabilities = Caps}, + codec = Opts} = S) -> #opts{cause = Cause, timeout = Tmo} = lists:foldl(fun opt/2, @@ -1340,7 +1389,7 @@ send_dpr(Reason, Opts, #state{dictionary = Dict, _ -> ?REBOOT end, timeout = dpa_timeout()}, - Opts), + DprOpts), #diameter_caps{origin_host = {OH, _}, origin_realm = {OR, _}} = Caps, @@ -1348,6 +1397,7 @@ send_dpr(Reason, Opts, #state{dictionary = Dict, Pkt = encode(['DPR', {'Origin-Host', OH}, {'Origin-Realm', OR}, {'Disconnect-Cause', Cause}], + Opts, Dict), send_dpr(false, Pkt, Tmo, S). |