%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2013-2017. 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%
%%
%%
%% Implements the handling of incoming and outgoing Diameter messages
%% except CER/CEA, DWR/DWA and DPR/DPA. That is, the messages that a
%% diameter client sends and receives.
%%
-module(diameter_traffic).
%% towards diameter
-export([send_request/4]).
%% towards diameter_watchdog
-export([receive_message/5]).
%% towards diameter_peer_fsm and diameter_watchdog
-export([incr/4,
incr_error/4,
incr_rc/4]).
%% towards diameter_service
-export([make_recvdata/1,
peer_up/1,
peer_down/1]).
%% internal
-export([send/1, %% send from remote node
init/1]). %% monitor process start
-include_lib("diameter/include/diameter.hrl").
-include("diameter_internal.hrl").
-define(LOGX(Reason, T), begin ?LOG(Reason, T), x({Reason, T}) end).
-define(RELAY, ?DIAMETER_DICT_RELAY).
-define(BASE, ?DIAMETER_DICT_COMMON). %% Note: the RFC 3588 dictionary
-define(DEFAULT(V, Def), if V == undefined -> Def; true -> V end).
%% Table containing outgoing entries that live and die with
%% peer_up/down. The name is historic, since the table used to contain
%% information about outgoing requests for which an answer has yet to
%% be received.
-define(REQUEST_TABLE, diameter_request).
%% Record diameter:call/4 options are parsed into.
-record(options,
{filter = none :: diameter:peer_filter(),
extra = [] :: list(),
timeout = 5000 :: 0..16#FFFFFFFF, %% for outgoing requests
detach = false :: boolean()}).
%% Term passed back to receive_message/6 with every incoming message.
-record(recvdata,
{peerT :: ets:tid(),
service_name :: diameter:service_name(),
apps :: [#diameter_app{}],
sequence :: diameter:sequence(),
codec :: #{string_decode := boolean(),
strict_mbit := boolean(),
incoming_maxlen := diameter:message_length()}}).
%% Note that incoming_maxlen is currently handled in diameter_peer_fsm,
%% so that any message exceeding the maximum is discarded. Retain the
%% option in case we want to extend the values and semantics.
%% Record stored in diameter_request for each outgoing request.
-record(request,
{ref :: reference(), %% used to receive answer
caller :: pid() | undefined, %% calling process
handler :: pid(), %% request process
peer :: undefined | {pid(), #diameter_caps{}},
packet :: #diameter_packet{} | undefined}). %% of request
%% ---------------------------------------------------------------------------
%% make_recvdata/1
%% ---------------------------------------------------------------------------
make_recvdata([SvcName, PeerT, Apps, SvcOpts | _]) ->
#{sequence := {_,_} = Mask, spawn_opt := Opts}
= SvcOpts,
{Opts, #recvdata{service_name = SvcName,
peerT = PeerT,
apps = Apps,
sequence = Mask,
codec = maps:with([string_decode,
strict_mbit,
ordered_encode,
incoming_maxlen],
SvcOpts)}}.
%% ---------------------------------------------------------------------------
%% peer_up/1
%% ---------------------------------------------------------------------------
%% Start a process that dies with peer_down/1, on which request
%% processes can monitor. There is no other process that dies with
%% peer_down since failover doesn't imply the loss of transport in the
%% case of a watchdog transition into state SUSPECT.
peer_up(TPid) ->
proc_lib:start(?MODULE, init, [TPid]).
init(TPid) ->
ets:insert(?REQUEST_TABLE, {TPid, self()}),
proc_lib:init_ack(self()),
proc_lib:hibernate(erlang, exit, [{shutdown, TPid}]).
%% ---------------------------------------------------------------------------
%% peer_down/1
%% ---------------------------------------------------------------------------
peer_down(TPid) ->
[{_, Pid}] = ets:lookup(?REQUEST_TABLE, TPid),
ets:delete(?REQUEST_TABLE, TPid),
Pid ! ok, %% make it die
Pid.
%% ---------------------------------------------------------------------------
%% incr/4
%% ---------------------------------------------------------------------------
incr(Dir, #diameter_packet{header = H}, TPid, AppDict) ->
incr(Dir, H, TPid, AppDict);
incr(Dir, #diameter_header{} = H, TPid, AppDict) ->
incr(TPid, {msg_id(H, AppDict), Dir}).
%% ---------------------------------------------------------------------------
%% incr_error/4
%% ---------------------------------------------------------------------------
%% Identify messages using the application dictionary, not the encode
%% dictionary, which may differ in the case of answer-message.
incr_error(Dir, T, Pid, {_MsgDict, AppDict}) ->
incr_error(Dir, T, Pid, AppDict);
%% Decoded message without errors.
incr_error(recv, #diameter_packet{errors = []}, _, _) ->
ok;
incr_error(recv = D, #diameter_packet{header = H}, TPid, AppDict) ->
incr_error(D, H, TPid, AppDict);
%% Encoded message with errors and an identifiable header ...
incr_error(send = D, {_, _, #diameter_header{} = H}, TPid, AppDict) ->
incr_error(D, H, TPid, AppDict);
%% ... or not.
incr_error(send = D, {_,_}, TPid, _) ->
incr_error(D, unknown, TPid);
incr_error(Dir, #diameter_header{} = H, TPid, AppDict) ->
incr_error(Dir, msg_id(H, AppDict), TPid);
incr_error(Dir, Id, TPid, _) ->
incr_error(Dir, Id, TPid).
incr_error(Dir, Id, TPid) ->
incr(TPid, {Id, Dir, error}).
%% ---------------------------------------------------------------------------
%% incr_rc/4
%% ---------------------------------------------------------------------------
-spec incr_rc(send|recv, Pkt, TPid, DictT)
-> {Counter, non_neg_integer()}
| Reason
when Pkt :: #diameter_packet{},
TPid :: pid(),
DictT :: module() | {MsgDict :: module(),
AppDict :: module(),
CommonDict:: module()},
Counter :: {'Result-Code', integer()}
| {'Experimental-Result', integer(), integer()},
Reason :: atom().
incr_rc(Dir, Pkt, TPid, {_, AppDict, _} = DictT) ->
try
incr_result(Dir, Pkt, TPid, DictT)
catch
exit: {E,_} when E == no_result_code;
E == invalid_error_bit ->
incr(TPid, {msg_id(Pkt#diameter_packet.header, AppDict), Dir, E}),
E
end;
incr_rc(Dir, Pkt, TPid, Dict0) ->
incr_rc(Dir, Pkt, TPid, {Dict0, Dict0, Dict0}).
%% ---------------------------------------------------------------------------
%% receive_message/5
%%
%% Handle an incoming Diameter message in a watchdog process.
%% ---------------------------------------------------------------------------
-spec receive_message(pid(), Route, #diameter_packet{}, module(), RecvData)
-> pid()
| boolean()
when Route :: {Handler, RequestRef, Seqs}
| Ack,
RecvData :: {[SpawnOpt], #recvdata{}},
SpawnOpt :: term(),
Handler :: pid(),
RequestRef :: reference(),
Seqs :: {0..16#FFFFFFFF, 0..16#FFFFFFFF},
Ack :: boolean().
receive_message(TPid, Route, Pkt, Dict0, RecvData) ->
#diameter_packet{header = #diameter_header{is_request = R}} = Pkt,
recv(R, Route, TPid, Pkt, Dict0, RecvData).
%% recv/6
%% Incoming request ...
recv(true, Ack, TPid, Pkt, Dict0, RecvData)
when is_boolean(Ack) ->
spawn_request(Ack, TPid, Pkt, Dict0, RecvData);
%% ... answer to known request ...
recv(false, {Pid, Ref, TPid}, _, Pkt, Dict0, _) ->
Pid ! {answer, Ref, TPid, Dict0, Pkt},
true;
%% Note that failover could have happened prior to this message being
%% received and triggering failback. That is, both a failover message
%% and answer may be on their way to the handler process. In the worst
%% case the request process gets notification of the failover and
%% sends to the alternate peer before an answer arrives, so it's
%% always the case that we can receive more than one answer after
%% failover. The first answer received by the request process wins,
%% any others are discarded.
%% ... or not.
recv(false, false, TPid, Pkt, _, _) ->
?LOG(discarded, Pkt#diameter_packet.header),
incr(TPid, {{unknown, 0}, recv, discarded}),
false.
%% spawn_request/5
spawn_request(Ack, TPid, Pkt, Dict0, {Opts, RecvData}) ->
spawn_opt(fun() ->
recv_request(Ack, TPid, Pkt, Dict0, RecvData)
end,
Opts).
%% ---------------------------------------------------------------------------
%% recv_request/5
%% ---------------------------------------------------------------------------
recv_request(Ack,
TPid,
#diameter_packet{header = #diameter_header{application_id = Id}}
= Pkt,
Dict0,
#recvdata{peerT = PeerT,
apps = Apps}
= RecvData) ->
Ack andalso (TPid ! {handler, self()}),
case diameter_service:find_incoming_app(PeerT, TPid, Id, Apps) of
{#diameter_app{id = Aid, dictionary = AppDict} = App, Caps} ->
incr(recv, Pkt, TPid, AppDict),
DecPkt = decode(Aid, AppDict, RecvData, Pkt),
incr_error(recv, DecPkt, TPid, AppDict),
send_A(recv_R(App, TPid, Dict0, Caps, RecvData, DecPkt),
TPid,
App,
Dict0,
RecvData,
DecPkt,
Caps);
#diameter_caps{} = Caps ->
%% DIAMETER_APPLICATION_UNSUPPORTED 3007
%% A request was sent for an application that is not
%% supported.
RC = 3007,
Es = Pkt#diameter_packet.errors,
DecPkt = Pkt#diameter_packet{avps = collect_avps(Pkt),
errors = [RC | Es]},
send_answer(answer_message(RC, Dict0, Caps, DecPkt),
TPid,
Dict0,
Dict0,
Dict0,
RecvData,
DecPkt,
[[]]);
false = No -> %% transport has gone down
No
end.
decode(Id, Dict, #recvdata{codec = Opts}, Pkt) ->
errors(Id, diameter_codec:decode(Id, Dict, Opts, Pkt)).
collect_avps(Pkt) ->
case diameter_codec:collect_avps(Pkt) of
{_Error, Avps} ->
Avps;
Avps ->
Avps
end.
%% send_A/7
send_A([T | Fs], TPid, App, Dict0, RecvData, DecPkt, Caps) ->
send_A(T, TPid, App, Dict0, RecvData, DecPkt, Caps, Fs);
send_A(discard = No, _, _, _, _, _, _) ->
No.
%% recv_R/6
%% Answer errors ourselves ...
recv_R(#diameter_app{options = [_, {request_errors, E} | _]},
_TPid,
Dict0,
_Caps,
_RecvData,
#diameter_packet{errors = [RC|_]}) %% a detected 3xxx is hd
when E == answer, Dict0 /= ?BASE orelse 3 == RC div 1000;
E == answer_3xxx, 3 == RC div 1000 ->
[{answer_message, rc(RC)}, []];
%% ... or make a handle_request callback. Note that
%% Pkt#diameter_packet.msg = undefined in the 3001 case.
recv_R(App,
TPid,
_Dict0,
Caps,
#recvdata{service_name = SvcName},
Pkt) ->
request_cb(cb(App, handle_request, [Pkt, SvcName, {TPid, Caps}]),
App,
[],
[]).
rc({N,_}) ->
N;
rc(N) ->
N.
%% errors/1
%%
%% Look for additional errors in a decoded message, prepending the
%% errors field with the first detected error. It's odd/unfortunate
%% that 501[15] aren't protocol errors. With RFC 3588 this means that
%% a handle_request callback has to formulate the answer. With RFC
%% 6733 it's acceptable for 5xxx to be sent in an answer-message.
%% DIAMETER_INVALID_MESSAGE_LENGTH 5015
%% This error is returned when a request is received with an invalid
%% message length.
errors(_, #diameter_packet{header = #diameter_header{length = Len} = H,
bin = Bin,
errors = Es}
= Pkt)
when Len < 20;
0 /= Len rem 4;
8*Len /= bit_size(Bin) ->
?LOG(invalid_message_length, {H, bit_size(Bin)}),
Pkt#diameter_packet{errors = [5015 | Es]};
%% DIAMETER_UNSUPPORTED_VERSION 5011
%% This error is returned when a request was received, whose version
%% number is unsupported.
errors(_, #diameter_packet{header = #diameter_header{version = V} = H,
errors = Es}
= Pkt)
when V /= ?DIAMETER_VERSION ->
?LOG(unsupported_version, H),
Pkt#diameter_packet{errors = [5011 | Es]};
%% DIAMETER_COMMAND_UNSUPPORTED 3001
%% The Request contained a Command-Code that the receiver did not
%% recognize or support. This MUST be used when a Diameter node
%% receives an experimental command that it does not understand.
errors(Id, #diameter_packet{header = #diameter_header{is_proxiable = P} = H,
msg = M,
errors = Es}
= Pkt)
when ?APP_ID_RELAY /= Id, undefined == M; %% don't know the command
?APP_ID_RELAY == Id, not P -> %% command isn't proxiable
?LOG(command_unsupported, H),
Pkt#diameter_packet{errors = [3001 | Es]};
%% DIAMETER_INVALID_HDR_BITS 3008
%% A request was received whose bits in the Diameter header were
%% either set to an invalid combination, or to a value that is
%% inconsistent with the command code's definition.
errors(_, #diameter_packet{header = #diameter_header{is_request = true,
is_error = true}
= H,
errors = Es}
= Pkt) ->
?LOG(invalid_hdr_bits, H),
Pkt#diameter_packet{errors = [3008 | Es]};
%% Green.
errors(_, Pkt) ->
Pkt.
%% request_cb/4
%% A reply may be an answer-message, constructed either here or by
%% the handle_request callback. The header from the incoming request
%% is passed into the encode so that it can retrieve the relevant
%% command code in this case. It will also then ignore Dict and use
%% the base encoder.
request_cb({reply, _Ans} = T, _App, EvalPktFs, EvalFs) ->
[T, EvalPktFs | EvalFs];
%% An 3xxx result code, for which the E-bit is set in the header.
request_cb({protocol_error, RC}, _App, EvalPktFs, EvalFs)
when 3 == RC div 1000 ->
[{answer_message, RC}, EvalPktFs | EvalFs];
request_cb({answer_message, RC} = T, _App, EvalPktFs, EvalFs)
when 3 == RC div 1000;
5 == RC div 1000 ->
[T, EvalPktFs | EvalFs];
%% RFC 3588 says we must reply 3001 to anything unrecognized or
%% unsupported. 'noreply' is undocumented (and inappropriately named)
%% backwards compatibility for this, protocol_error the documented
%% alternative.
request_cb(noreply, _App, EvalPktFs, EvalFs) ->
[{answer_message, 3001}, EvalPktFs | EvalFs];
%% Relay a request to another peer. This is equivalent to doing an
%% explicit call/4 with the message in question except that (1) a loop
%% will be detected by examining Route-Record AVP's, (3) a
%% Route-Record AVP will be added to the outgoing request and (3) the
%% End-to-End Identifier will default to that in the
%% #diameter_header{} without the need for an end_to_end_identifier
%% option.
%%
%% relay and proxy are similar in that they require the same handling
%% with respect to Route-Record and End-to-End identifier. The
%% difference is that a proxy advertises specific applications, while
%% a relay advertises the relay application. If a callback doesn't
%% want to distinguish between the cases in the callback return value
%% then 'resend' is a neutral alternative.
%%
request_cb({A, Opts}, #diameter_app{id = Id}, EvalPktFs, EvalFs)
when A == relay, Id == ?APP_ID_RELAY;
A == proxy, Id /= ?APP_ID_RELAY;
A == resend ->
[{call, Opts}, EvalPktFs | EvalFs];
request_cb(discard = No, _, _, _) ->
No;
request_cb({eval_packet, RC, F}, App, Fs, EvalFs) ->
request_cb(RC, App, [F|Fs], EvalFs);
request_cb({eval, RC, F}, App, EvalPktFs, Fs) ->
request_cb(RC, App, EvalPktFs, [F|Fs]);
request_cb(T, App, _, _) ->
?ERROR({invalid_return, T, handle_request, App}).
%% send_A/8
send_A({reply, Ans}, TPid, App, Dict0, RecvData, Pkt, _Caps, Fs) ->
AppDict = App#diameter_app.dictionary,
MsgDict = msg_dict(AppDict, Dict0, Ans),
send_answer(Ans,
TPid,
MsgDict,
AppDict,
Dict0,
RecvData,
Pkt,
Fs);
send_A({call, Opts}, TPid, App, Dict0, RecvData, Pkt, Caps, Fs) ->
AppDict = App#diameter_app.dictionary,
case resend(Opts, Caps, Pkt, App, Dict0, RecvData) of
#diameter_packet{bin = Bin} = Ans -> %% answer: reset hop by hop id
#diameter_packet{header = #diameter_header{hop_by_hop_id = Id},
transport_data = TD}
= Pkt,
Reset = diameter_codec:hop_by_hop_id(Id, Bin),
MsgDict = msg_dict(AppDict, Dict0, Ans),
send_answer(Ans#diameter_packet{bin = Reset,
transport_data = TD},
TPid,
MsgDict,
AppDict,
Dict0,
Fs);
RC ->
send_answer(answer_message(RC, Dict0, Caps, Pkt),
TPid,
Dict0,
AppDict,
Dict0,
RecvData,
Pkt,
Fs)
end;
%% RFC 3588 only allows 3xxx errors in an answer-message. RFC 6733
%% added the possibility of setting 5xxx.
send_A({answer_message, RC} = T, TPid, App, Dict0, RecvData, Pkt, Caps, Fs) ->
Dict0 /= ?BASE orelse 3 == RC div 1000
orelse ?ERROR({invalid_return, T, handle_request, App}),
send_answer(answer_message(RC, Dict0, Caps, Pkt),
TPid,
Dict0,
App#diameter_app.dictionary,
Dict0,
RecvData,
Pkt,
Fs).
%% send_answer/8
%% Skip the setting of Result-Code and Failed-AVP's below. This is
%% undocumented and shouldn't be relied on.
send_answer([Ans], TPid, MsgDict, AppDict, Dict0, RecvData, Pkt, Fs)
when [] == Pkt#diameter_packet.errors ->
send_answer(Ans, TPid, MsgDict, AppDict, Dict0, RecvData, Pkt, Fs);
send_answer([Ans], TPid, MsgDict, AppDict, Dict0, RecvData, Pkt0, Fs) ->
Pkt = Pkt0#diameter_packet{errors = []},
send_answer(Ans, TPid, MsgDict, AppDict, Dict0, RecvData, Pkt, Fs);
send_answer(Ans, TPid, MsgDict, AppDict, Dict0, RecvData, DecPkt, Fs) ->
Pkt = encode({MsgDict, AppDict},
TPid,
RecvData#recvdata.codec,
make_answer_packet(Ans, DecPkt, MsgDict, Dict0)),
send_answer(Pkt, TPid, MsgDict, AppDict, Dict0, Fs).
%% send_answer/6
send_answer(Pkt, TPid, MsgDict, AppDict, Dict0, [EvalPktFs | EvalFs]) ->
eval_packet(Pkt, EvalPktFs),
incr(send, Pkt, TPid, AppDict),
incr_rc(send, Pkt, TPid, {MsgDict, AppDict, Dict0}), %% count outgoing
send(TPid, Pkt, _Route = self()),
lists:foreach(fun diameter_lib:eval/1, EvalFs).
%% msg_dict/3
%%
%% Return the dictionary defining the message grammar in question: the
%% application dictionary or the common dictionary.
msg_dict(AppDict, Dict0, [Msg]) ->
msg_dict(AppDict, Dict0, Msg);
msg_dict(AppDict, Dict0, Msg) ->
choose(is_answer_message(Msg, Dict0), Dict0, AppDict).
%% Incoming, not yet decoded.
is_answer_message(#diameter_packet{header = #diameter_header{} = H,
msg = undefined},
Dict0) ->
is_answer_message([H], Dict0);
is_answer_message(#diameter_packet{msg = Msg}, Dict0) ->
is_answer_message(Msg, Dict0);
%% Message sent as a header/avps list.
is_answer_message([#diameter_header{is_request = R, is_error = E} | _], _) ->
E andalso not R;
%% Message sent as a tagged avp/value list.
is_answer_message([Name | _], _) ->
Name == 'answer-message';
%% Message sent as a record.
is_answer_message(Rec, Dict) ->
try
'answer-message' == Dict:rec2msg(element(1,Rec))
catch
error:_ -> false
end.
%% resend/6
resend(Opts, Caps, Pkt, App, Dict0, RecvData) ->
resend(is_loop(Dict0, Caps, Pkt), Opts, Caps, Pkt, App, Dict0, RecvData).
%% resend/7
%% DIAMETER_LOOP_DETECTED 3005
%% An agent detected a loop while trying to get the message to the
%% intended recipient. The message MAY be sent to an alternate peer,
%% if one is available, but the peer reporting the error has
%% identified a configuration problem.
resend(true, _Opts, _Caps, _Pkt, _App, _Dict0, _RecvData) ->
3005;
%% 6.1.8. Relaying and Proxying Requests
%%
%% A relay or proxy agent MUST append a Route-Record AVP to all requests
%% forwarded. The AVP contains the identity of the peer the request was
%% received from.
resend(false,
Opts,
#diameter_caps{origin_host = {_,OH}},
#diameter_packet{header = Hdr0,
avps = Avps},
App,
Dict0,
#recvdata{service_name = SvcName,
sequence = Mask}) ->
Route = #diameter_avp{data = {Dict0, 'Route-Record', OH}},
Seq = diameter_session:sequence(Mask),
Hdr = Hdr0#diameter_header{hop_by_hop_id = Seq},
Msg = [Hdr, Route | Avps], %% reordered at encode
case send_request(SvcName, App, Msg, Opts) of
#diameter_packet{} = Ans ->
Ans;
_ ->
3002 %% DIAMETER_UNABLE_TO_DELIVER.
end.
%% The incoming request is relayed with the addition of a
%% Route-Record. Note the requirement on the return from call/4 below,
%% which places a requirement on the value returned by the
%% handle_answer callback of the application module in question.
%%
%% Note that there's nothing stopping the request from being relayed
%% back to the sender. A pick_peer callback may want to avoid this but
%% a smart peer might recognize the potential loop and choose another
%% route. A less smart one will probably just relay the request back
%% again and force us to detect the loop. A pick_peer that wants to
%% avoid this can specify filter to avoid the possibility.
%% Eg. {neg, {host, OH} where #diameter_caps{origin_host = {OH, _}}.
%%
%% RFC 6.3 says that a relay agent does not modify Origin-Host but
%% says nothing about a proxy. Assume it should behave the same way.
%% is_loop/3
is_loop(Dict0,
#diameter_caps{origin_host = {OH,_}},
#diameter_packet{avps = Avps}) ->
{Code, _Flags, Vid} = Dict0:avp_header('Route-Record'),
is_loop(Code, Vid, OH, Avps).
%% is_loop/4
%%
%% Is there a Route-Record AVP with our Origin-Host?
is_loop(Code, Vid, Bin, [#diameter_avp{code = Code,
vendor_id = Vid,
data = Bin}
| _]) ->
true;
is_loop(_, _, _, []) ->
false;
is_loop(Code, Vid, OH, [_ | Avps])
when is_binary(OH) ->
is_loop(Code, Vid, OH, Avps);
is_loop(Code, Vid, OH, Avps) ->
is_loop(Code, Vid, list_to_binary(OH), Avps).
%% select_error/3
%%
%% Extract the first appropriate RC or {RC, #diameter_avp{}}
%% pair from an errors list, along with any leading #diameter_avp{}.
%%
%% RFC 6733:
%%
%% 7.5. Failed-AVP AVP
%%
%% The Failed-AVP AVP (AVP Code 279) is of type Grouped and provides
%% debugging information in cases where a request is rejected or not
%% fully processed due to erroneous information in a specific AVP. The
%% value of the Result-Code AVP will provide information on the reason
%% for the Failed-AVP AVP. A Diameter answer message SHOULD contain an
%% instance of the Failed-AVP AVP that corresponds to the error
%% indicated by the Result-Code AVP. For practical purposes, this
%% Failed-AVP would typically refer to the first AVP processing error
%% that a Diameter node encounters.
%%
%% 3xxx can only be set in an answer setting the E-bit. RFC 6733 also
%% allows 5xxx, RFC 3588 doesn't.
select_error(E, Es, Dict0) ->
select(E, Es, Dict0, []).
%% select/4
select(E, [{RC, _} = T | Es], Dict0, Avps) ->
select(E, RC, T, Es, Dict0, Avps);
select(E, [#diameter_avp{} = A | Es], Dict0, Avps) ->
select(E, Es, Dict0, [A | Avps]);
select(E, [RC | Es], Dict0, Avps) ->
select(E, RC, RC, Es, Dict0, Avps);
select(_, [], _, Avps) ->
Avps.
%% select/6
select(E, RC, T, _, Dict0, Avps)
when E, 3000 =< RC, RC < 4000; %% E-bit with 3xxx
E, ?BASE /= Dict0, 5000 =< RC, RC < 6000; %% E-bit with 5xxx
not E, RC < 3000 orelse 4000 =< RC -> %% no E-bit
[T | Avps];
select(E, _, _, Es, Dict0, Avps) ->
select(E, Es, Dict0, Avps).
%% eval_packet/2
eval_packet(Pkt, Fs) ->
lists:foreach(fun(F) -> diameter_lib:eval([F,Pkt]) end, Fs).
%% make_answer_packet/4
%% Use decode errors to set Result-Code and/or Failed-AVP unless the
%% the errors field has been explicitly set. Unfortunately, the
%% default value is the empty list rather than 'undefined' so use the
%% atom 'false' for "set nothing". (This is historical and changing
%% the default value would impact anyone expecting relying on the old
%% default.)
make_answer_packet(#diameter_packet{header = Hdr,
msg = Msg,
errors = Es,
transport_data = TD},
#diameter_packet{header = Hdr0,
errors = Es0},
MsgDict,
Dict0) ->
#diameter_packet{header = make_answer_header(Hdr0, Hdr),
msg = reset(Msg, Es0, Es, MsgDict, Dict0),
transport_data = TD};
%% Binaries and header/avp lists are sent as-is.
make_answer_packet(Bin, #diameter_packet{transport_data = TD}, _, _)
when is_binary(Bin) ->
#diameter_packet{bin = Bin,
transport_data = TD};
make_answer_packet([#diameter_header{} | _] = Msg,
#diameter_packet{transport_data = TD},
_,
_) ->
#diameter_packet{msg = Msg,
transport_data = TD};
make_answer_packet(Msg,
#diameter_packet{header = Hdr,
errors = Es,
transport_data = TD},
MsgDict,
Dict0) ->
#diameter_packet{header = make_answer_header(Hdr, undefined),
msg = reset(Msg, [], Es, MsgDict, Dict0),
transport_data = TD}.
%% make_answer_header/2
%% A reply message clears the R and T flags and retains the P flag.
%% The E flag will be set at encode. 6.2 of 3588 requires the same P
%% flag on an answer as on the request. A #diameter_packet{} returned
%% from a handle_request callback can circumvent this by setting its
%% own header values.
make_answer_header(ReqHdr, Hdr) ->
Hdr0 = ReqHdr#diameter_header{version = ?DIAMETER_VERSION,
is_request = false,
is_error = undefined,
is_retransmitted = false},
fold_record(Hdr0, Hdr).
%% reset/5
reset(Msg, [_|_] = Es0, [] = Es, MsgDict, Dict0) ->
reset(Msg, Es, Es0, MsgDict, Dict0);
reset(Msg, _, Es, _, _)
when Es == false;
Es == [] ->
Msg;
reset(Msg, _, Es, MsgDict, Dict0) ->
E = is_answer_message(Msg, Dict0),
reset(Msg, select_error(E, Es, Dict0), choose(E, Dict0, MsgDict)).
%% reset/4
%%
%% Set Result-Code and/or Failed-AVP (maybe). Only RC and {RC, AVP}
%% are the result of decode. AVP or {RC, [AVP]} can be set in an
%% answer for encode, as a convenience for injecting additional AVPs
%% into Failed-AVP; eg. 5001 = DIAMETER_AVP_UNSUPPORTED.
reset(Msg, [], _) ->
Msg;
reset(Msg, [{RC, As} | Avps], Dict)
when is_list(As) ->
reset(Msg, [RC | As ++ Avps], Dict);
reset(Msg, [{RC, Avp} | Avps], Dict) ->
reset(Msg, [RC, Avp | Avps], Dict);
reset(Msg, [#diameter_avp{} | _] = Avps, Dict) ->
set(Msg, failed_avp(Msg, Avps, Dict), Dict);
reset(Msg, [RC | Avps], Dict) ->
set(Msg, rc(Msg, RC, Dict) ++ failed_avp(Msg, Avps, Dict), Dict).
%% set/3
%% Reply as name and tuple list ...
set([_|_] = Ans, Avps, _) ->
Ans ++ Avps; %% Values nearer tail take precedence.
%% ... or record.
set(Rec, Avps, Dict) ->
Dict:'#set-'(Avps, Rec).
%% rc/3
%%
%% Turn the result code into a list if its optional and only set it if
%% the arity is 1 or {0,1}. In other cases (which probably shouldn't
%% exist in practice) we can't know what's appropriate.
rc([MsgName | _], RC, Dict) ->
K = 'Result-Code',
case Dict:avp_arity(MsgName, K) of
1 -> [{K, RC}];
{0,1} -> [{K, [RC]}];
_ -> []
end;
rc(Rec, RC, Dict) ->
rc([Dict:rec2msg(element(1, Rec))], RC, Dict).
%% failed_avp/3
failed_avp(_, [] = No, _) ->
No;
failed_avp(Msg, [_|_] = Avps, Dict) ->
[failed(Msg, [{'AVP', Avps}], Dict)].
%% Reply as name and tuple list ...
failed([MsgName | Values], FailedAvp, Dict) ->
RecName = Dict:msg2rec(MsgName),
try
Dict:'#info-'(RecName, {index, 'Failed-AVP'}),
{'Failed-AVP', [FailedAvp]}
catch
error: _ ->
Avps = proplists:get_value('AVP', Values, []),
A = #diameter_avp{name = 'Failed-AVP',
value = FailedAvp},
{'AVP', [A|Avps]}
end;
%% ... or record.
failed(Rec, FailedAvp, Dict) ->
try
RecName = element(1, Rec),
Dict:'#info-'(RecName, {index, 'Failed-AVP'}),
{'Failed-AVP', [FailedAvp]}
catch
error: _ ->
Avps = Dict:'#get-'('AVP', Rec),
A = #diameter_avp{name = 'Failed-AVP',
value = FailedAvp},
{'AVP', [A|Avps]}
end.
%% 3. Diameter Header
%%
%% E(rror) - If set, the message contains a protocol error,
%% and the message will not conform to the ABNF
%% described for this command. Messages with the 'E'
%% bit set are commonly referred to as error
%% messages. This bit MUST NOT be set in request
%% messages. See Section 7.2.
%% 3.2. Command Code ABNF specification
%%
%% e-bit = ", ERR"
%% ; If present, the 'E' bit in the Command
%% ; Flags is set, indicating that the answer
%% ; message contains a Result-Code AVP in
%% ; the "protocol error" class.
%% 7.1.3. Protocol Errors
%%
%% Errors that fall within the Protocol Error category SHOULD be treated
%% on a per-hop basis, and Diameter proxies MAY attempt to correct the
%% error, if it is possible. Note that these and only these errors MUST
%% only be used in answer messages whose 'E' bit is set.
%% Thus, only construct answers to protocol errors. Other errors
%% require an message-specific answer and must be handled by the
%% application.
%% 6.2. Diameter Answer Processing
%%
%% When a request is locally processed, the following procedures MUST be
%% applied to create the associated answer, in addition to any
%% additional procedures that MAY be discussed in the Diameter
%% application defining the command:
%%
%% - The same Hop-by-Hop identifier in the request is used in the
%% answer.
%%
%% - The local host's identity is encoded in the Origin-Host AVP.
%%
%% - The Destination-Host and Destination-Realm AVPs MUST NOT be
%% present in the answer message.
%%
%% - The Result-Code AVP is added with its value indicating success or
%% failure.
%%
%% - If the Session-Id is present in the request, it MUST be included
%% in the answer.
%%
%% - Any Proxy-Info AVPs in the request MUST be added to the answer
%% message, in the same order they were present in the request.
%%
%% - The 'P' bit is set to the same value as the one in the request.
%%
%% - The same End-to-End identifier in the request is used in the
%% answer.
%%
%% Note that the error messages (see Section 7.3) are also subjected to
%% the above processing rules.
%% 7.3. Error-Message AVP
%%
%% The Error-Message AVP (AVP Code 281) is of type UTF8String. It MAY
%% accompany a Result-Code AVP as a human readable error message. The
%% Error-Message AVP is not intended to be useful in real-time, and
%% SHOULD NOT be expected to be parsed by network entities.
%% answer_message/4
answer_message(RC,
Dict0,
#diameter_caps{origin_host = {OH,_},
origin_realm = {OR,_}},
#diameter_packet{avps = Avps,
errors = Es}) ->
{Code, _, Vid} = Dict0:avp_header('Session-Id'),
['answer-message', {'Origin-Host', OH},
{'Origin-Realm', OR},
{'Result-Code', RC}]
++ session_id(Code, Vid, Avps)
++ failed_avp(RC, Es).
session_id(Code, Vid, Avps)
when is_list(Avps) ->
try
#diameter_avp{data = Bin} = find_avp(Code, Vid, Avps),
[{'Session-Id', [Bin]}]
catch
error: _ ->
[]
end.
%% Note that this should only match 5xxx result codes currently but
%% don't bother distinguishing this case.
failed_avp(RC, [{RC, Avp} | _]) ->
[{'Failed-AVP', [{'AVP', [Avp]}]}];
failed_avp(RC, [_ | Es]) ->
failed_avp(RC, Es);
failed_avp(_, [] = No) ->
No.
%% find_avp/3
%% Grouped ...
find_avp(Code, VId, [[#diameter_avp{code = Code, vendor_id = VId} | _] = As
| _]) ->
As;
%% ... or not.
find_avp(Code, VId, [#diameter_avp{code = Code, vendor_id = VId} = A | _]) ->
A;
find_avp(Code, VId, [_ | Avps]) ->
find_avp(Code, VId, Avps).
%% 7. Error Handling
%%
%% There are certain Result-Code AVP application errors that require
%% additional AVPs to be present in the answer. In these cases, the
%% Diameter node that sets the Result-Code AVP to indicate the error
%% MUST add the AVPs. Examples are:
%%
%% - An unrecognized AVP is received with the 'M' bit (Mandatory bit)
%% set, causes an answer to be sent with the Result-Code AVP set to
%% DIAMETER_AVP_UNSUPPORTED, and the Failed-AVP AVP containing the
%% offending AVP.
%%
%% - An AVP that is received with an unrecognized value causes an
%% answer to be returned with the Result-Code AVP set to
%% DIAMETER_INVALID_AVP_VALUE, with the Failed-AVP AVP containing the
%% AVP causing the error.
%%
%% - A command is received with an AVP that is omitted, yet is
%% mandatory according to the command's ABNF. The receiver issues an
%% answer with the Result-Code set to DIAMETER_MISSING_AVP, and
%% creates an AVP with the AVP Code and other fields set as expected
%% in the missing AVP. The created AVP is then added to the Failed-
%% AVP AVP.
%%
%% The Result-Code AVP describes the error that the Diameter node
%% encountered in its processing. In case there are multiple errors,
%% the Diameter node MUST report only the first error it encountered
%% (detected possibly in some implementation dependent order). The
%% specific errors that can be described by this AVP are described in
%% the following section.
%% 7.5. Failed-AVP AVP
%%
%% The Failed-AVP AVP (AVP Code 279) is of type Grouped and provides
%% debugging information in cases where a request is rejected or not
%% fully processed due to erroneous information in a specific AVP. The
%% value of the Result-Code AVP will provide information on the reason
%% for the Failed-AVP AVP.
%%
%% The possible reasons for this AVP are the presence of an improperly
%% constructed AVP, an unsupported or unrecognized AVP, an invalid AVP
%% value, the omission of a required AVP, the presence of an explicitly
%% excluded AVP (see tables in Section 10), or the presence of two or
%% more occurrences of an AVP which is restricted to 0, 1, or 0-1
%% occurrences.
%%
%% A Diameter message MAY contain one Failed-AVP AVP, containing the
%% entire AVP that could not be processed successfully. If the failure
%% reason is omission of a required AVP, an AVP with the missing AVP
%% code, the missing vendor id, and a zero filled payload of the minimum
%% required length for the omitted AVP will be added.
%% incr_result/5
%%
%% Increment a stats counter for result codes in incoming and outgoing
%% answers.
%% Message sent as a header/avps list.
incr_result(send = Dir,
#diameter_packet{msg = [#diameter_header{} = H | _]}
= Pkt,
TPid,
DictT) ->
incr_res(Dir, Pkt#diameter_packet{header = H}, TPid, DictT);
%% Outgoing message as binary: don't count. (Sending binaries is only
%% partially supported.)
incr_result(send, #diameter_packet{header = undefined = No}, _, _) ->
No;
%% Incoming or outgoing. Outgoing with encode errors never gets here
%% since encode fails.
incr_result(Dir, Pkt, TPid, DictT) ->
incr_res(Dir, Pkt, TPid, DictT).
incr_res(Dir,
#diameter_packet{header = #diameter_header{is_error = E}
= Hdr,
errors = Es}
= Pkt,
TPid,
DictT) ->
{MsgDict, AppDict, Dict0} = DictT,
Id = msg_id(Hdr, AppDict),
%% Could be {relay, 0}, in which case the R-bit is redundant since
%% only answers are being counted. Let it be however, so that the
%% same tuple is in both send/recv and result code counters.
%% Count incoming decode errors.
recv /= Dir orelse [] == Es orelse incr_error(Dir, Id, TPid, AppDict),
%% Exit on a missing result code.
T = rc_counter(MsgDict, Dir, Pkt),
T == false andalso ?LOGX(no_result_code, {MsgDict, Dir, Hdr}),
{Ctr, RC, Avp} = T,
%% Or on an inappropriate value.
is_result(RC, E, Dict0)
orelse ?LOGX(invalid_error_bit, {MsgDict, Dir, Hdr, Avp}),
incr(TPid, {Id, Dir, Ctr}),
Ctr.
%% msg_id/2
msg_id(#diameter_packet{header = H}, AppDict) ->
msg_id(H, AppDict);
%% Only count on known keys so as not to be vulnerable to attack:
%% there are 2^32 (application ids) * 2^24 (command codes) = 2^56
%% pairs for an attacker to choose from.
msg_id(Hdr, AppDict) ->
{Aid, Code, R} = Id = diameter_codec:msg_id(Hdr),
case AppDict:id() of
?APP_ID_RELAY ->
{relay, R};
A ->
unknown(A /= Aid orelse '' == AppDict:msg_name(Code, 0 == R), Id)
end.
unknown(true, {_, _, R}) ->
{unknown, R};
unknown(false, Id) ->
Id.
%% No E-bit: can't be 3xxx.
is_result(RC, false, _Dict0) ->
RC < 3000 orelse 4000 =< RC;
%% E-bit in RFC 3588: only 3xxx.
is_result(RC, true, ?BASE) ->
3000 =< RC andalso RC < 4000;
%% E-bit in RFC 6733: 3xxx or 5xxx.
is_result(RC, true, _) ->
3000 =< RC andalso RC < 4000
orelse
5000 =< RC andalso RC < 6000.
%% incr/2
incr(TPid, Counter) ->
diameter_stats:incr(Counter, TPid, 1).
%% rc_counter/3
%% RFC 3588, 7.6:
%%
%% All Diameter answer messages defined in vendor-specific
%% applications MUST include either one Result-Code AVP or one
%% Experimental-Result AVP.
rc_counter(Dict, Dir, #diameter_packet{header = H,
avps = As,
msg = Msg})
when Dir == recv; %% decoded incoming
Msg == undefined -> %% relayed outgoing
rc_counter(Dict, [H|As]);
rc_counter(Dict, _, #diameter_packet{msg = Msg}) ->
rc_counter(Dict, Msg).
rc_counter(Dict, Msg) ->
rcc(get_result(Dict, Msg)).
rcc(#diameter_avp{name = 'Result-Code' = Name, value = N} = A)
when is_integer(N) ->
{{Name, N}, N, A};
rcc(#diameter_avp{name = 'Result-Code' = Name, value = [N|_]} = A)
when is_integer(N) ->
{{Name, N}, N, A};
rcc(#diameter_avp{name = 'Experimental-Result', value = {_,_,N} = T} = A)
when is_integer(N) ->
{T, N, A};
rcc(#diameter_avp{name = 'Experimental-Result', value = [{_,_,N} = T|_]} = A)
when is_integer(N) ->
{T, N, A};
rcc(_) ->
false.
%% get_result/2
get_result(Dict, Msg) ->
try
[throw(A) || N <- ['Result-Code', 'Experimental-Result'],
#diameter_avp{} = A <- [get_avp(Dict, N, Msg)]]
catch
#diameter_avp{} = A -> A
end.
x(T) ->
exit(T).
%% ---------------------------------------------------------------------------
%% send_request/4
%%
%% Handle an outgoing Diameter request.
%% ---------------------------------------------------------------------------
send_request(SvcName, AppOrAlias, Msg, Options)
when is_list(Options) ->
Rec = make_options(Options),
Ref = make_ref(),
Caller = {self(), Ref},
ReqF = fun() ->
exit({Ref, send_R(SvcName, AppOrAlias, Msg, Rec, Caller)})
end,
try spawn_monitor(ReqF) of
{_, MRef} ->
recv_A(MRef, Ref, Rec#options.detach, false)
catch
error: system_limit = E ->
{error, E}
end.
%% The R in send_R is because Diameter request are usually given short
%% names of the form XXR. (eg. CER, DWR, etc.) Similarly, answers have
%% names of the form XXA.
%% Don't rely on gen_server:call/3 for the timeout handling since it
%% makes no guarantees about not leaving a reply message in the
%% mailbox if we catch its exit at timeout. It currently *can* do so,
%% which is also undocumented.
recv_A(MRef, _, true, true) ->
erlang:demonitor(MRef, [flush]),
ok;
recv_A(MRef, Ref, Detach, Sent) ->
receive
Ref -> %% send has been attempted
recv_A(MRef, Ref, Detach, true);
{'DOWN', MRef, process, _, Reason} ->
answer_rc(Reason, Ref, Sent)
end.
%% send_R/5 has returned ...
answer_rc({Ref, Ans}, Ref, _) ->
Ans;
%% ... or not. Note that failure/encode are documented return values.
answer_rc(_, _, Sent) ->
{error, choose(Sent, failure, encode)}.
%% send_R/5
%%
%% In the process spawned for the outgoing request.
send_R(SvcName, AppOrAlias, Msg, CallOpts, Caller) ->
case pick_peer(SvcName, AppOrAlias, Msg, CallOpts) of
{{_,_} = Transport, SvcOpts} ->
send_request(Transport, SvcOpts, Msg, CallOpts, Caller, SvcName);
{error, _} = No ->
No
end.
%% make_options/1
make_options(Options) ->
make_opts(Options, false, [], none, 5000).
%% Do our own recursion since this is faster than a lists:foldl/3
%% setting elements in an #options{} accumulator.
make_opts([], Detach, Extra, Filter, Tmo) ->
#options{detach = Detach,
extra = Extra,
filter = Filter,
timeout = Tmo};
make_opts([{timeout, Tmo} | Rest], Detach, Extra, Filter, _)
when is_integer(Tmo), 0 =< Tmo ->
make_opts(Rest, Detach, Extra, Filter, Tmo);
make_opts([{filter, F} | Rest], Detach, Extra, none, Tmo) ->
make_opts(Rest, Detach, Extra, F, Tmo);
make_opts([{filter, F} | Rest], Detach, Extra, {all, Fs}, Tmo) ->
make_opts(Rest, Detach, Extra, {all, [F|Fs]}, Tmo);
make_opts([{filter, F} | Rest], Detach, Extra, F0, Tmo) ->
make_opts(Rest, Detach, Extra, {all, [F0, F]}, Tmo);
make_opts([{extra, L} | Rest], Detach, Extra, Filter, Tmo)
when is_list(L) ->
make_opts(Rest, Detach, Extra ++ L, Filter, Tmo);
make_opts([detach | Rest], _, Extra, Filter, Tmo) ->
make_opts(Rest, true, Extra, Filter, Tmo);
make_opts([T | _], _, _, _, _) ->
?ERROR({invalid_option, T}).
%% ---------------------------------------------------------------------------
%% send_request/6
%% ---------------------------------------------------------------------------
%% Send an outgoing request in its dedicated process.
%%
%% Note that both encode of the outgoing request and of the received
%% answer happens in this process. It's also this process that replies
%% to the caller. The service process only handles the state-retaining
%% callbacks.
%%
%% The module field of the #diameter_app{} here includes any extra
%% arguments passed to diameter:call/4.
send_request({{TPid, _Caps} = TC, App}
= Transport,
#{sequence := Mask}
= SvcOpts,
Msg0,
CallOpts,
Caller,
SvcName) ->
Pkt = make_prepare_packet(Mask, Msg0),
case prepare(cb(App, prepare_request, [Pkt, SvcName, TC]), []) of
[Msg | Fs] ->
ReqPkt = make_request_packet(Msg, Pkt),
EncPkt = encode(App#diameter_app.dictionary,
TPid,
SvcOpts,
ReqPkt),
eval_packet(EncPkt, Fs),
T = send_R(ReqPkt, EncPkt, Transport, CallOpts, Caller, SvcName),
Ans = recv_answer(SvcName, App, CallOpts, T),
handle_answer(SvcName, SvcOpts, App, Ans);
{discard, Reason} ->
{error, Reason};
discard ->
{error, discarded};
{error, Reason} ->
?ERROR({invalid_return, Reason, prepare_request, App})
end.
%% prepare/2
prepare({send, Msg}, Fs) ->
[Msg | Fs];
prepare({eval_packet, RC, F}, Fs) ->
prepare(RC, [F|Fs]);
prepare({discard, _Reason} = RC, _) ->
RC;
prepare(discard = RC, _) ->
RC;
prepare(Reason, _) ->
{error, Reason}.
%% make_prepare_packet/2
%%
%% Turn an outgoing request as passed to call/4 into a diameter_packet
%% record in preparation for a prepare_request callback.
make_prepare_packet(_, Bin)
when is_binary(Bin) ->
#diameter_packet{header = diameter_codec:decode_header(Bin),
bin = Bin};
make_prepare_packet(Mask, #diameter_packet{msg = [#diameter_header{} = Hdr
| Avps]}
= Pkt) ->
Pkt#diameter_packet{msg = [make_prepare_header(Mask, Hdr) | Avps]};
make_prepare_packet(Mask, #diameter_packet{header = Hdr} = Pkt) ->
Pkt#diameter_packet{header = make_prepare_header(Mask, Hdr)};
make_prepare_packet(Mask, [#diameter_header{} = Hdr | Avps]) ->
#diameter_packet{msg = [make_prepare_header(Mask, Hdr) | Avps]};
make_prepare_packet(Mask, Msg) ->
#diameter_packet{header = make_prepare_header(Mask, undefined),
msg = Msg}.
%% make_prepare_header/2
make_prepare_header(Mask, undefined) ->
Seq = diameter_session:sequence(Mask),
#diameter_header{version = ?DIAMETER_VERSION,
end_to_end_id = Seq,
hop_by_hop_id = Seq};
make_prepare_header(Mask, #diameter_header{version = V,
end_to_end_id = EI,
hop_by_hop_id = HI}
= H)
when EI == undefined;
HI == undefined ->
Id = diameter_session:sequence(Mask),
H#diameter_header{version = ?DEFAULT(V, ?DIAMETER_VERSION),
end_to_end_id = ?DEFAULT(EI, Id),
hop_by_hop_id = ?DEFAULT(HI, Id)};
make_prepare_header(_, #diameter_header{version = undefined} = H) ->
H#diameter_header{version = ?DIAMETER_VERSION};
make_prepare_header(_, #diameter_header{} = H) ->
H;
make_prepare_header(_, T) ->
?ERROR({invalid_header, T}).
%% make_request_packet/2
%%
%% Reconstruct a diameter_packet from the return value of
%% prepare_request or prepare_retransmit callback.
make_request_packet(Bin, _)
when is_binary(Bin) ->
make_prepare_packet(false, Bin);
make_request_packet(#diameter_packet{msg = [#diameter_header{} | _]}
= Pkt,
_) ->
Pkt;
%% Returning a diameter_packet with no header from a prepare_request
%% or prepare_retransmit callback retains the header passed into it.
%% This is primarily so that the end to end and hop by hop identifiers
%% are retained.
make_request_packet(#diameter_packet{header = Hdr} = Pkt,
#diameter_packet{header = Hdr0}) ->
Pkt#diameter_packet{header = fold_record(Hdr0, Hdr)};
make_request_packet(Msg, Pkt) ->
Pkt#diameter_packet{msg = Msg}.
%% make_retransmit_packet/1
make_retransmit_packet(#diameter_packet{msg = [#diameter_header{} = Hdr
| Avps]}
= Pkt) ->
Pkt#diameter_packet{msg = [make_retransmit_header(Hdr) | Avps]};
make_retransmit_packet(#diameter_packet{header = Hdr} = Pkt) ->
Pkt#diameter_packet{header = make_retransmit_header(Hdr)}.
%% make_retransmit_header/1
make_retransmit_header(Hdr) ->
Hdr#diameter_header{is_retransmitted = true}.
%% fold_record/2
%%
%% Replace elements in the first record by those in the second that
%% differ from undefined.
fold_record(Rec0, undefined) ->
Rec0;
fold_record(Rec0, Rec) ->
list_to_tuple(fold(tuple_to_list(Rec0), tuple_to_list(Rec))).
fold([], []) ->
[];
fold([H | T0], [undefined | T]) ->
[H | fold(T0, T)];
fold([_ | T0], [H | T]) ->
[H | fold(T0, T)].
%% send_R/6
send_R(ReqPkt,
EncPkt,
{{TPid, _Caps} = TC, #diameter_app{dictionary = AppDict}},
#options{timeout = Timeout},
{Pid, Ref},
SvcName) ->
Req = #request{ref = Ref,
caller = Pid,
handler = self(),
peer = TC,
packet = ReqPkt},
incr(send, EncPkt, TPid, AppDict),
{TRef, MRef} = zend_requezt(TPid, EncPkt, Req, SvcName, Timeout),
Pid ! Ref, %% tell caller a send has been attempted
{TRef, MRef, Req}.
%% recv_answer/4
recv_answer(SvcName, App, CallOpts, {TRef, MRef, #request{ref = Ref}
= Req}) ->
%% Matching on TRef below ensures we ignore messages that pertain
%% to a previous transport prior to failover. The answer message
%% includes the pid of the transport on which it was received,
%% which may not be the last peer to which we've transmitted.
receive
{answer = A, Ref, TPid, Dict0, Pkt} -> %% Answer from peer
{A, #request{} = erase(TPid), Dict0, Pkt};
{timeout = Reason, TRef, _} -> %% No timely reply
{error, Req, Reason};
{'DOWN', MRef, process, _, _} when false /= MRef -> %% local peer_down
failover(SvcName, App, Req, CallOpts);
{failover, TRef} -> %% local or remote peer_down
failover(SvcName, App, Req, CallOpts)
end.
%% failover/4
failover(SvcName, App, Req, CallOpts) ->
resend_request(pick_peer(SvcName, App, Req, CallOpts),
Req,
CallOpts,
SvcName).
%% handle_answer/4
handle_answer(SvcName, _, App, {error, Req, Reason}) ->
#request{packet = Pkt,
peer = {_TPid, _Caps} = TC}
= Req,
cb(App, handle_error, [Reason, msg(Pkt), SvcName, TC]);
handle_answer(SvcName,
SvcOpts,
#diameter_app{id = Id,
dictionary = AppDict,
options = [{answer_errors, AE} | _]}
= App,
{answer, Req, Dict0, Pkt}) ->
MsgDict = msg_dict(AppDict, Dict0, Pkt),
DecPkt = errors(Id, diameter_codec:decode({MsgDict, AppDict},
SvcOpts,
Pkt)),
#request{peer = {TPid, _}}
= Req,
incr(recv, DecPkt, TPid, AppDict),
AnsPkt = try
incr_result(recv, DecPkt, TPid, {MsgDict, AppDict, Dict0})
of
_ -> DecPkt
catch
exit: {no_result_code, _} ->
%% RFC 6733 requires one of Result-Code or
%% Experimental-Result, but the decode will have
%% detected a missing AVP. If both are optional in
%% the dictionary then this isn't a decode error:
%% just continue on.
DecPkt;
exit: {invalid_error_bit, {_, _, _, Avp}} ->
#diameter_packet{errors = Es}
= DecPkt,
E = {5004, Avp},
DecPkt#diameter_packet{errors = [E|Es]}
end,
handle_answer(AnsPkt, SvcName, App, AE, Req).
%% handle_answer/5
handle_answer(#diameter_packet{errors = Es}
= Pkt,
SvcName,
App,
AE,
#request{peer = {_TPid, _Caps} = TC,
packet = P})
when callback == AE;
[] == Es ->
cb(App, handle_answer, [Pkt, msg(P), SvcName, TC]);
handle_answer(#diameter_packet{header = H}, SvcName, _, AE, _) ->
handle_error(H, SvcName, AE).
%% handle_error/3
-spec handle_error(_, _, _) -> no_return(). %% silence dialyzer
handle_error(Hdr, SvcName, report) ->
MFA = {?MODULE, handle_answer, [SvcName, Hdr]},
diameter_lib:warning_report(errors, MFA),
handle_error(Hdr, SvcName, discard);
handle_error(Hdr, SvcName, discard) ->
x({answer_errors, {SvcName, Hdr}}).
%% Note that we don't check that the application id in the answer's
%% header is what we expect. (TODO: Does the rfc says anything about
%% this?)
%% Note that failover starts a new timer and that expiry of an old
%% timer value is ignored. This means that an answer could be accepted
%% from a peer after timeout in the case of failover.
%% resend_request/4
resend_request({{{TPid, _Caps} = TC, App}, SvcOpts},
Req0,
#options{timeout = Timeout}
= CallOpts,
SvcName) ->
case
undefined == get(TPid)
andalso prepare_retransmit(TC, App, Req0, SvcName)
of
[ReqPkt | Fs] ->
AppDict = App#diameter_app.dictionary,
EncPkt = encode(AppDict, TPid, SvcOpts, ReqPkt),
eval_packet(EncPkt, Fs),
Req = Req0#request{peer = TC,
packet = ReqPkt},
?LOG(retransmission, EncPkt#diameter_packet.header),
incr(TPid, {msg_id(EncPkt, AppDict), send, retransmission}),
{TRef, MRef} = zend_requezt(TPid, EncPkt, Req, SvcName, Timeout),
recv_answer(SvcName, App, CallOpts, {TRef, MRef, Req});
false ->
{error, Req0, timeout};
{discard, Reason} ->
{error, Req0, Reason};
discard ->
{error, Req0, discarded};
{error, T} ->
?ERROR({invalid_return, T, prepare_retransmit, App})
end;
resend_request(_, Req, _, _) -> %% no alternate peer
{error, Req, failover}.
%% pick_peer/4
%% Retransmission after failover: call-specific arguments have already
%% been appended in App.
pick_peer(SvcName,
App,
#request{packet = #diameter_packet{msg = Msg}},
CallOpts) ->
pick_peer(SvcName, App, Msg, CallOpts#options{extra = []});
pick_peer(_, _, undefined, _) ->
{error, no_connection};
pick_peer(SvcName,
AppOrAlias,
Msg,
#options{filter = Filter, extra = Xtra}) ->
X = {fun(D) -> get_destination(D, Msg) end, Filter, Xtra},
case diameter_service:pick_peer(SvcName, AppOrAlias, X) of
false ->
{error, no_connection};
T ->
T
end.
msg(#diameter_packet{msg = undefined, bin = Bin}) ->
Bin;
msg(#diameter_packet{msg = Msg}) ->
Msg.
%% encode/4
%% Note that prepare_request can return a diameter_packet containing a
%% header or transport_data. Even allow the returned record to contain
%% an encoded binary. This isn't the usual case and doesn't properly
%% support retransmission but is useful for test.
encode(Dict, TPid, Opts, Pkt)
when is_atom(Dict) ->
encode({Dict, Dict}, TPid, Opts, Pkt);
%% A message to be encoded.
encode(DictT, TPid, Opts, #diameter_packet{bin = undefined} = Pkt) ->
{Dict, AppDict} = DictT,
try
diameter_codec:encode(Dict, Opts, Pkt)
catch
exit: {diameter_codec, encode, T} = Reason ->
incr_error(send, T, TPid, AppDict),
exit(Reason)
end;
%% An encoded binary: just send.
encode(_, _, _, #diameter_packet{} = Pkt) ->
Pkt.
%% zend_requezt/5
%%
%% Strip potentially large record fields that aren't used by the
%% processes the records can be send to, possibly on a remote node.
zend_requezt(TPid, Pkt, Req, SvcName, Timeout) ->
put(TPid, Req),
send_request(TPid, z(Pkt), Req, SvcName, Timeout).
%% send_request/5
send_request(TPid, #diameter_packet{bin = Bin} = Pkt, Req, _SvcName, Timeout)
when node() == node(TPid) ->
Seqs = diameter_codec:sequence_numbers(Bin),
TRef = erlang:start_timer(Timeout, self(), TPid),
send(TPid, Pkt, _Route = {self(), Req#request.ref, Seqs}),
{TRef, _MRef = peer_monitor(TPid, TRef)};
%% Send using a remote transport: spawn a process on the remote node
%% to relay the answer.
send_request(TPid, #diameter_packet{} = Pkt, Req, SvcName, Timeout) ->
TRef = erlang:start_timer(Timeout, self(), TPid),
T = {TPid, Pkt, z(Req), SvcName, Timeout, TRef},
spawn(node(TPid), ?MODULE, send, [T]),
{TRef, false}.
%% z/1
%%
%% Avoid sending potentially large terms unnecessarily. The records
%% themselves are retained since they're sent between nodes in send/1
%% and changing what's sent causes upgrade issues.
z(#request{ref = Ref, handler = Pid}) ->
#request{ref = Ref,
handler = Pid};
z(#diameter_packet{header = H, bin = Bin, transport_data = T}) ->
#diameter_packet{header = H,
bin = Bin,
transport_data = T}.
%% send/1
send({TPid, Pkt, #request{handler = Pid} = Req0, SvcName, Timeout, TRef}) ->
Req = Req0#request{handler = self()},
recv(TPid, Pid, TRef, zend_requezt(TPid, Pkt, Req, SvcName, Timeout)).
%% recv/4
%%
%% Relay an answer from a remote node.
recv(TPid, Pid, TRef, {LocalTRef, MRef}) ->
receive
{answer, _, _, _, _} = A ->
Pid ! A;
{'DOWN', MRef, process, _, _} ->
Pid ! {failover, TRef};
{failover = T, LocalTRef} ->
Pid ! {T, TRef};
T ->
exit({timeout, LocalTRef, TPid} = T)
end.
%% send/3
send(Pid, Pkt, Route) ->
Pid ! {send, Pkt, Route}.
%% prepare_retransmit/4
prepare_retransmit({_TPid, _Caps} = TC, App, Req, SvcName) ->
Pkt = make_retransmit_packet(Req#request.packet),
case prepare(cb(App, prepare_retransmit, [Pkt, SvcName, TC]), []) of
[Msg | Fs] ->
[make_request_packet(Msg, Pkt) | Fs];
No ->
No
end.
%% When sending a binary, it's up to prepare_retransmit to modify it
%% accordingly.
%% peer_monitor/2
peer_monitor(TPid, TRef) ->
case ets:lookup(?REQUEST_TABLE, TPid) of %% at peer_up/1
[{_, MPid}] ->
monitor(process, MPid);
[] -> %% transport has gone down
self() ! {failover, TRef},
false
end.
%% get_destination/2
get_destination(Dict, Msg) ->
[str(get_avp_value(Dict, D, Msg)) || D <- ['Destination-Realm',
'Destination-Host']].
%% This is not entirely correct. The avp could have an arity 1, in
%% which case an empty list is a DiameterIdentity of length 0 rather
%% than the list of no values we treat it as by mapping to undefined.
%% This behaviour is documented.
str([]) ->
undefined;
str(T) ->
T.
%% get_avp/3
%%
%% Find an AVP in a message of one of three forms:
%%
%% - a message record (as generated from a .dia spec) or
%% - a list of an atom message name followed by 2-tuple, avp name/value pairs.
%% - a list of a #diameter_header{} followed by #diameter_avp{} records,
%%
%% In the first two forms a dictionary module is used at encode to
%% identify the type of the AVP and its arity in the message in
%% question. The third form allows messages to be sent as is, without
%% a dictionary, which is needed in the case of relay agents, for one.
%% Messages will be header/avps list as a relay and the only AVP's we
%% look for are in the common dictionary. This is required since the
%% relay dictionary doesn't inherit the common dictionary (which maybe
%% it should).
get_avp(?RELAY, Name, Msg) ->
get_avp(?BASE, Name, Msg);
%% Message as a header/avps list.
get_avp(Dict, Name, [#diameter_header{} | Avps]) ->
try
{Code, _, VId} = Dict:avp_header(Name),
find_avp(Code, VId, Avps)
of
A ->
(avp_decode(Dict, Name, ungroup(A)))#diameter_avp{name = Name}
catch
error: _ ->
undefined
end;
%% Outgoing message as a name/values list.
get_avp(_, Name, [_MsgName | Avps]) ->
case lists:keyfind(Name, 1, Avps) of
{_, V} ->
#diameter_avp{name = Name, value = V};
_ ->
undefined
end;
%% Message is typically a record but not necessarily.
get_avp(Dict, Name, Rec) ->
try
#diameter_avp{name = Name, value = Dict:'#get-'(Name, Rec)}
catch
error:_ ->
undefined
end.
%% get_avp_value/3
get_avp_value(Dict, Name, Msg) ->
case get_avp(Dict, Name, Msg) of
#diameter_avp{value = V} ->
V;
undefined = No ->
No
end.
%% ungroup/1
ungroup([Avp|_]) ->
Avp;
ungroup(Avp) ->
Avp.
%% avp_decode/3
avp_decode(Dict, Name, #diameter_avp{value = undefined,
data = Bin}
= Avp) ->
try Dict:avp(decode, Bin, Name, decode_opts(Dict)) of
V ->
Avp#diameter_avp{value = V}
catch
error:_ ->
Avp
end;
avp_decode(_, _, #diameter_avp{} = Avp) ->
Avp.
cb(#diameter_app{module = [_|_] = M}, F, A) ->
eval(M, F, A).
eval([M|X], F, A) ->
apply(M, F, A ++ X).
choose(true, X, _) -> X;
choose(false, _, X) -> X.
%% Decode options sufficient for AVP extraction.
decode_opts(Dict) ->
#{string_decode => false,
strict_mbit => false,
failed_avp => false,
dictionary => Dict}.