%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2010-2014. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
%%
%% This file contains code that's included by encode/decode modules
%% generated by diameter_codegen.erl. This code does most of the work, the
%% generated code being kept simple.
%%
-define(THROW(T), throw({?MODULE, T})).
%% Key to a value in the process dictionary that determines whether or
%% not an unrecognized AVP setting the M-bit should be regarded as an
%% error or not. See is_strict/0.
-define(STRICT_KEY, strict).
-type parent_name() :: atom(). %% parent = Message or AVP
-type parent_record() :: tuple(). %%
-type avp_name() :: atom().
-type avp_record() :: tuple().
-type avp_values() :: [{avp_name(), term()}].
-type non_grouped_avp() :: #diameter_avp{}.
-type grouped_avp() :: nonempty_improper_list(#diameter_avp{}, [avp()]).
-type avp() :: non_grouped_avp() | grouped_avp().
%% Use a (hopefully) unique key when manipulating the process
%% dictionary.
putr(K,V) ->
put({?MODULE, K}, V).
getr(K) ->
get({?MODULE, K}).
eraser(K) ->
erase({?MODULE, K}).
%% ---------------------------------------------------------------------------
%% # encode_avps/2
%% ---------------------------------------------------------------------------
-spec encode_avps(parent_name(), parent_record() | avp_values())
-> binary()
| no_return().
encode_avps(Name, Vals)
when is_list(Vals) ->
encode_avps(Name, '#set-'(Vals, newrec(Name)));
encode_avps(Name, Rec) ->
try
list_to_binary(encode(Name, Rec))
catch
throw: {?MODULE, Reason} ->
diameter_lib:log({encode, error},
?MODULE,
?LINE,
{Reason, Name, Rec}),
erlang:error(list_to_tuple(Reason ++ [Name]));
error: Reason ->
Stack = erlang:get_stacktrace(),
diameter_lib:log({encode, failure},
?MODULE,
?LINE,
{Reason, Name, Rec, Stack}),
erlang:error({encode_failure, Reason, Name, Stack})
end.
%% encode/2
encode(Name, Rec) ->
lists:flatmap(fun(A) -> encode(Name, A, '#get-'(A, Rec)) end,
'#info-'(element(1, Rec), fields)).
%% encode/3
encode(Name, AvpName, Values) ->
e(Name, AvpName, avp_arity(Name, AvpName), Values).
%% e/4
e(_, AvpName, 1, undefined) ->
?THROW([mandatory_avp_missing, AvpName]);
e(Name, AvpName, 1, Value) ->
e(Name, AvpName, [Value]);
e(_, _, {0,_}, []) ->
[];
e(_, AvpName, _, T)
when not is_list(T) ->
?THROW([repeated_avp_as_non_list, AvpName, T]);
e(_, AvpName, {Min, _}, L)
when length(L) < Min ->
?THROW([repeated_avp_insufficient_arity, AvpName, Min, L]);
e(_, AvpName, {_, Max}, L)
when Max < length(L) ->
?THROW([repeated_avp_excessive_arity, AvpName, Max, L]);
e(Name, AvpName, _, Values) ->
e(Name, AvpName, Values).
%% e/3
e(Name, 'AVP', Values) ->
[pack_AVP(Name, A) || A <- Values];
e(_, AvpName, Values) ->
e(AvpName, Values).
%% e/2
e(AvpName, Values) ->
H = avp_header(AvpName),
[diameter_codec:pack_avp(H, avp(encode, V, AvpName)) || V <- Values].
%% pack_AVP/2
%% No value: assume AVP data is already encoded. The normal case will
%% be when this is passed back from #diameter_packet.errors as a
%% consequence of a failed decode. Any AVP can be encoded this way
%% however, which side-steps any arity checks for known AVP's and
%% could potentially encode something unfortunate.
pack_AVP(_, #diameter_avp{value = undefined} = A) ->
diameter_codec:pack_avp(A);
%% Missing name for value encode.
pack_AVP(_, #diameter_avp{name = N, value = V})
when N == undefined;
N == 'AVP' ->
?THROW([value_with_nameless_avp, N, V]);
%% Or not. Ensure that 'AVP' is the appropriate field. Note that if we
%% don't know this AVP at all then the encode will fail.
pack_AVP(Name, #diameter_avp{name = AvpName,
value = Data}) ->
0 == avp_arity(Name, AvpName)
orelse ?THROW([known_avp_as_AVP, Name, AvpName, Data]),
e(AvpName, [Data]).
%% ---------------------------------------------------------------------------
%% # decode_avps/2
%% ---------------------------------------------------------------------------
-spec decode_avps(parent_name(), [#diameter_avp{}])
-> {parent_record(), [avp()], Failed}
when Failed :: [{5000..5999, #diameter_avp{}}].
decode_avps(Name, Recs) ->
{Avps, {Rec, Failed}}
= lists:foldl(fun(T,A) -> decode(Name, T, A) end,
{[], {newrec(Name), []}},
Recs),
{Rec, Avps, Failed ++ missing(Rec, Name)}.
%% Append 5005 errors so that a 5014 for the same AVP will take
%% precedence in a Result-Code/Failed-AVP setting.
newrec(Name) ->
'#new-'(name2rec(Name)).
%% 3588:
%%
%% DIAMETER_MISSING_AVP 5005
%% The request did not contain an AVP that is required by the Command
%% Code definition. If this value is sent in the Result-Code AVP, a
%% Failed-AVP AVP SHOULD be included in the message. The Failed-AVP
%% AVP MUST contain an example of the missing AVP complete with the
%% Vendor-Id if applicable. The value field of the missing AVP
%% should be of correct minimum length and contain zeroes.
missing(Rec, Name) ->
[{5005, empty_avp(F)} || F <- '#info-'(element(1, Rec), fields),
A <- [avp_arity(Name, F)],
false <- [have_arity(A, '#get-'(F, Rec))]].
%% Maximum arities have already been checked in building the record.
have_arity({Min, _}, L) ->
Min =< length(L);
have_arity(N, V) ->
N /= 1 orelse V /= undefined.
%% empty_avp/1
empty_avp(Name) ->
{Code, Flags, VId} = avp_header(Name),
{Name, Type} = avp_name(Code, VId),
#diameter_avp{name = Name,
code = Code,
vendor_id = VId,
is_mandatory = 0 /= (Flags band 2#01000000),
need_encryption = 0 /= (Flags band 2#00100000),
data = empty_value(Name),
type = Type}.
%% 3588, ch 7:
%%
%% 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.
%% decode/3
decode(Name, #diameter_avp{code = Code, vendor_id = Vid} = Avp, Acc) ->
decode(Name, avp_name(Code, Vid), Avp, Acc).
%% decode/4
%% AVP is defined in the dictionary ...
decode(Name, {AvpName, Type}, Avp, Acc) ->
d(Name, Avp#diameter_avp{name = AvpName, type = Type}, Acc);
%% ... or not.
decode(Name, 'AVP', Avp, Acc) ->
decode_AVP(Name, Avp, Acc).
%% 6733, 4.4:
%%
%% Receivers of a Grouped AVP that does not have the 'M' (mandatory)
%% bit set and one or more of the encapsulated AVPs within the group
%% has the 'M' (mandatory) bit set MAY simply be ignored if the
%% Grouped AVP itself is unrecognized. The rule applies even if the
%% encapsulated AVP with its 'M' (mandatory) bit set is further
%% encapsulated within other sub-groups, i.e., other Grouped AVPs
%% embedded within the Grouped AVP.
%%
%% The first sentence is slightly mangled, but take it to mean this:
%%
%% An unrecognized AVP of type Grouped that does not set the 'M' bit
%% MAY be ignored even if one of its encapsulated AVPs sets the 'M'
%% bit.
%%
%% The text above is a change from RFC 3588, which instead says this:
%%
%% Further, if any of the AVPs encapsulated within a Grouped AVP has
%% the 'M' (mandatory) bit set, the Grouped AVP itself MUST also
%% include the 'M' bit set.
%%
%% Both of these texts have problems. If the AVP is unknown then its
%% type is unknown since the type isn't sent over the wire, so the
%% 6733 text becomes a non-statement: don't know that the AVP not
%% setting the M-bit is of type Grouped, therefore can't know that its
%% data consists of encapsulated AVPs, therefore can't but ignore that
%% one of these might set the M-bit. It should be no worse if we know
%% the AVP to have type Grouped.
%%
%% Similarly, for the 3588 text: if we receive an AVP that doesn't set
%% the M-bit and don't know that the AVP has type Grouped then we
%% can't realize that its data contains an AVP that sets the M-bit, so
%% can't regard the AVP as erroneous on this account. Again, it should
%% be no worse if the type is known to be Grouped, but in this case
%% the RFC forces us to regard the AVP as erroneous. This is
%% inconsistent, and the 3588 text has never been enforced.
%%
%% So, if an AVP doesn't set the M-bit then we're free to ignore it,
%% regardless of the AVP's type. If we know the type to be Grouped
%% then we must ignore the M-bit on an encapsulated AVP. That means
%% packing such an encapsulated AVP into an 'AVP' field if need be,
%% not regarding the lack of a specific field as an error as is
%% otherwise the case. (The lack of an AVP-specific field being how we
%% defined the RFC's "unrecognized", which is slightly stronger than
%% "not defined".)
%% d/3
%% Don't try to decode the value of a Failed-AVP component since it
%% probably won't. Note that matching on 'Failed-AVP' assumes that
%% this is the RFC AVP, with code 279. Strictly, this doesn't need to
%% be the case, so we're assuming no one defines another Failed-AVP.
d('Failed-AVP' = Name, Avp, Acc) ->
decode_AVP(Name, Avp, Acc);
%% Or try to decode.
d(Name, Avp, {Avps, Acc}) ->
#diameter_avp{name = AvpName,
data = Data,
type = Type,
is_mandatory = M}
= Avp,
%% Use the process dictionary is to keep track of whether or not
%% to ignore an M-bit on an encapsulated AVP. Not ideal, but the
%% alternative requires widespread changes to be able to pass the
%% value around through the entire decode. The solution here is
%% simple in comparison, both to implement and to understand.
Reset = relax(Type, M),
try avp(decode, Data, AvpName) of
V ->
{H, A} = ungroup(V, Avp),
{[H | Avps], pack_avp(Name, A, Acc)}
catch
error: Reason ->
%% Failures here won't be visible since they're a "normal"
%% occurrence if the peer sends a faulty AVP that we need to
%% respond sensibly to. Log the occurence for traceability,
%% but the peer will also receive info in the resulting
%% answer-message.
diameter_lib:log({decode, failure},
?MODULE,
?LINE,
{Reason, Avp, erlang:get_stacktrace()}),
{Rec, Failed} = Acc,
{[Avp|Avps], {Rec, [rc(Reason, Avp) | Failed]}}
after
relax(Reset)
end.
%% Set false in the process dictionary as soon as we see a Grouped AVP
%% that doesn't set the M-bit, so that is_strict() can say whether or
%% not to ignore the M-bit on an encapsulated AVP.
relax('Grouped', M) ->
V = getr(?STRICT_KEY),
if V == undefined andalso not M ->
putr(?STRICT_KEY, M);
true ->
false
end;
relax(_, _) ->
false.
%% Reset strictness.
relax(undefined) ->
eraser(?STRICT_KEY);
relax(false) ->
ok.
is_strict() ->
false /= getr(?STRICT_KEY).
%% decode_AVP/3
%%
%% Don't know this AVP: see if it can be packed in an 'AVP' field
%% undecoded. Note that the type field is 'undefined' in this case.
decode_AVP(Name, Avp, {Avps, Acc}) ->
{[Avp | Avps], pack_AVP(Name, Avp, Acc)}.
%% rc/1
%% diameter_types will raise an error of this form to communicate
%% DIAMETER_INVALID_AVP_LENGTH (5014). A module specified to a
%% @custom_types tag in a spec file can also raise an error of this
%% form.
rc({'DIAMETER', 5014 = RC, _}, #diameter_avp{name = AvpName} = Avp) ->
{RC, Avp#diameter_avp{data = empty_value(AvpName)}};
%% 3588:
%%
%% DIAMETER_INVALID_AVP_VALUE 5004
%% The request contained an AVP with an invalid value in its data
%% portion. A Diameter message indicating this error MUST include
%% the offending AVPs within a Failed-AVP AVP.
rc(_, Avp) ->
{5004, Avp}.
%% ungroup/2
-spec ungroup(term(), #diameter_avp{})
-> {avp(), #diameter_avp{}}.
%% The decoded value in the Grouped case is as returned by grouped_avp/3:
%% a record and a list of component AVP's.
ungroup(V, #diameter_avp{type = 'Grouped'} = Avp) ->
{Rec, As} = V,
A = Avp#diameter_avp{value = Rec},
{[A|As], A};
%% Otherwise it's just a plain value.
ungroup(V, #diameter_avp{} = Avp) ->
A = Avp#diameter_avp{value = V},
{A, A}.
%% pack_avp/3
pack_avp(Name, #diameter_avp{name = AvpName} = Avp, Acc) ->
pack_avp(Name, avp_arity(Name, AvpName), Avp, Acc).
%% pack_avp/4
pack_avp(Name, 0, Avp, Acc) ->
pack_AVP(Name, Avp, Acc);
pack_avp(_, Arity, Avp, Acc) ->
pack(Arity, Avp#diameter_avp.name, Avp, Acc).
%% pack_AVP/3
pack_AVP(Name, #diameter_avp{is_mandatory = M} = Avp, Acc) ->
case pack_arity(Name, M) of
0 ->
{Rec, Failed} = Acc,
{Rec, [{if M -> 5001; true -> 5008 end, Avp} | Failed]};
Arity ->
pack(Arity, 'AVP', Avp, Acc)
end.
%% Give Failed-AVP special treatment since it'll contain any
%% unrecognized mandatory AVP's.
pack_arity(Name, M) ->
case Name /= 'Failed-AVP' andalso M andalso is_strict() of
true ->
0;
false ->
avp_arity(Name, 'AVP')
end.
%% 3588:
%%
%% DIAMETER_AVP_UNSUPPORTED 5001
%% The peer received a message that contained an AVP that is not
%% recognized or supported and was marked with the Mandatory bit. A
%% Diameter message with this error MUST contain one or more Failed-
%% AVP AVP containing the AVPs that caused the failure.
%%
%% DIAMETER_AVP_NOT_ALLOWED 5008
%% A message was received with an AVP that MUST NOT be present. The
%% Failed-AVP AVP MUST be included and contain a copy of the
%% offending AVP.
%% pack/4
pack(Arity, FieldName, Avp, {Rec, _} = Acc) ->
pack('#get-'(FieldName, Rec), Arity, FieldName, Avp, Acc).
%% pack/5
pack(undefined, 1, FieldName, Avp, Acc) ->
p(FieldName, fun(V) -> V end, Avp, Acc);
%% 3588:
%%
%% DIAMETER_AVP_OCCURS_TOO_MANY_TIMES 5009
%% A message was received that included an AVP that appeared more
%% often than permitted in the message definition. The Failed-AVP
%% AVP MUST be included and contain a copy of the first instance of
%% the offending AVP that exceeded the maximum number of occurrences
%%
pack(_, 1, _, Avp, {Rec, Failed}) ->
{Rec, [{5009, Avp} | Failed]};
pack(L, {_, Max}, _, Avp, {Rec, Failed})
when length(L) == Max ->
{Rec, [{5009, Avp} | Failed]};
pack(L, _, FieldName, Avp, Acc) ->
p(FieldName, fun(V) -> [V|L] end, Avp, Acc).
%% p/4
p(F, Fun, Avp, {Rec, Failed}) ->
{'#set-'({F, Fun(value(F, Avp))}, Rec), Failed}.
value('AVP', Avp) ->
Avp;
value(_, Avp) ->
Avp#diameter_avp.value.
%% ---------------------------------------------------------------------------
%% # grouped_avp/3
%% ---------------------------------------------------------------------------
-spec grouped_avp(decode, avp_name(), binary())
-> {avp_record(), [avp()]};
(encode, avp_name(), avp_record() | avp_values())
-> binary()
| no_return().
grouped_avp(decode, Name, Data) ->
{Rec, Avps, []} = decode_avps(Name, diameter_codec:collect_avps(Data)),
{Rec, Avps};
%% A failed match here will result in 5004. Note that this is the only
%% AVP type that doesn't just return the decoded record, also
%% returning the list of component AVP's.
grouped_avp(encode, Name, Data) ->
encode_avps(Name, Data).
%% ---------------------------------------------------------------------------
%% # empty_group/1
%% ---------------------------------------------------------------------------
empty_group(Name) ->
list_to_binary(empty_body(Name)).
empty_body(Name) ->
[z(F, avp_arity(Name, F)) || F <- '#info-'(name2rec(Name), fields)].
z(Name, 1) ->
z(Name);
z(_, {0,_}) ->
[];
z(Name, {Min, _}) ->
lists:duplicate(Min, z(Name)).
z('AVP') ->
<<0:64/integer>>; %% minimal header
z(Name) ->
Bin = diameter_codec:pack_avp(avp_header(Name), empty_value(Name)),
<< <<0>> || <<_>> <= Bin >>.
%% ---------------------------------------------------------------------------
%% # empty/1
%% ---------------------------------------------------------------------------
empty(AvpName) ->
avp(encode, zero, AvpName).
