%% %% %CopyrightBegin% %% %% Copyright Ericsson AB 2010-2013. 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% %% -module(diameter_codec). -export([encode/2, decode/2, decode/3, collect_avps/1, decode_header/1, sequence_numbers/1, hop_by_hop_id/2, msg_name/2, msg_id/1]). %% Towards generated encoders (from diameter_gen.hrl). -export([pack_avp/1, pack_avp/2]). -include_lib("diameter/include/diameter.hrl"). -include("diameter_internal.hrl"). -define(MASK(N,I), ((I) band (1 bsl (N)))). %% 0 1 2 3 %% 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 %% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ %% | Version | Message Length | %% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ %% | command flags | Command-Code | %% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ %% | Application-ID | %% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ %% | Hop-by-Hop Identifier | %% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ %% | End-to-End Identifier | %% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ %% | AVPs ... %% +-+-+-+-+-+-+-+-+-+-+-+-+- %%% --------------------------------------------------------------------------- %%% # encode/[2-4] %%% --------------------------------------------------------------------------- encode(Mod, #diameter_packet{} = Pkt) -> try e(Mod, Pkt) catch error: Reason -> %% Be verbose since a crash report may be truncated and %% encode errors are self-inflicted. X = {?MODULE, encode, {Reason, ?STACK}}, diameter_lib:error_report(X, {?MODULE, encode, [Mod, Pkt]}), exit(X) end; encode(Mod, Msg) -> Seq = diameter_session:sequence(), Hdr = #diameter_header{version = ?DIAMETER_VERSION, end_to_end_id = Seq, hop_by_hop_id = Seq}, encode(Mod, #diameter_packet{header = Hdr, msg = Msg}). e(_, #diameter_packet{msg = [#diameter_header{} = Hdr | As]} = Pkt) -> Avps = encode_avps(As), Length = size(Avps) + 20, #diameter_header{version = Vsn, cmd_code = Code, application_id = Aid, hop_by_hop_id = Hid, end_to_end_id = Eid} = Hdr, Flags = make_flags(0, Hdr), Pkt#diameter_packet{header = Hdr, bin = <>}; e(Mod, #diameter_packet{header = Hdr, msg = Msg} = Pkt) -> #diameter_header{version = Vsn, hop_by_hop_id = Hid, end_to_end_id = Eid} = Hdr, MsgName = rec2msg(Mod, Msg), {Code, Flags0, Aid} = msg_header(Mod, MsgName, Hdr), Flags = make_flags(Flags0, Hdr), Avps = encode_avps(Mod, MsgName, values(Msg)), Length = size(Avps) + 20, Pkt#diameter_packet{header = Hdr#diameter_header {length = Length, cmd_code = Code, application_id = Aid, is_request = 0 /= ?MASK(7, Flags), is_proxiable = 0 /= ?MASK(6, Flags), is_error = 0 /= ?MASK(5, Flags), is_retransmitted = 0 /= ?MASK(4, Flags)}, bin = <>}. %% make_flags/2 make_flags(Flags0, #diameter_header{is_request = R, is_proxiable = P, is_error = E, is_retransmitted = T}) -> {Flags, 3} = lists:foldl(fun(B,{F,N}) -> {mf(B,F,N), N-1} end, {Flags0, 7}, [R,P,E,T]), Flags. mf(undefined, F, _) -> F; mf(B, F, N) -> %% reset the affected bit (F bxor (F band (1 bsl N))) bor bit(B, N). bit(true, N) -> 1 bsl N; bit(false, _) -> 0. %% values/1 values([H|T]) when is_atom(H) -> T; values(Avps) -> Avps. %% encode_avps/3 %% Specifying values as a #diameter_avp list bypasses arity and other %% checks: the values are expected to be already encoded and the AVP's %% presented are simply sent. This is needed for relay agents, since %% these have to be able to resend whatever comes. %% Message as a list of #diameter_avp{} ... encode_avps(_, _, [#diameter_avp{} | _] = Avps) -> encode_avps(reorder(Avps, [], Avps)); %% ... or as a tuple list or record. encode_avps(Mod, MsgName, Values) -> Mod:encode_avps(MsgName, Values). %% reorder/1 reorder([#diameter_avp{index = 0} | _] = Avps, Acc, _) -> Avps ++ Acc; reorder([#diameter_avp{index = N} = A | Avps], Acc, _) when is_integer(N) -> lists:reverse(Avps, [A | Acc]); reorder([H | T], Acc, Avps) -> reorder(T, [H | Acc], Avps); reorder([], Acc, _) -> Acc. %% encode_avps/1 encode_avps(Avps) -> list_to_binary(lists:map(fun pack_avp/1, Avps)). %% msg_header/3 msg_header(Mod, 'answer-message' = MsgName, Header) -> 0 = Mod:id(), %% assert #diameter_header{application_id = Aid, cmd_code = Code} = Header, {-1, Flags, ?DIAMETER_APP_ID_COMMON} = Mod:msg_header(MsgName), {Code, Flags, Aid}; msg_header(Mod, MsgName, _) -> Mod:msg_header(MsgName). %% rec2msg/2 rec2msg(_, [Name|_]) when is_atom(Name) -> Name; rec2msg(Mod, Rec) -> Mod:rec2msg(element(1, Rec)). %%% --------------------------------------------------------------------------- %%% # decode/2 %%% --------------------------------------------------------------------------- %% Unsuccessfully decoded AVPs will be placed in #diameter_packet.errors. decode(Mod, Pkt) -> decode(Mod:id(), Mod, Pkt). %% If we're a relay application then just extract the avp's without %% any decoding of their data since we don't know the application in %% question. decode(?APP_ID_RELAY, _, #diameter_packet{} = Pkt) -> case collect_avps(Pkt) of {E, As} -> Pkt#diameter_packet{avps = As, errors = [E]}; As -> Pkt#diameter_packet{avps = As} end; %% Otherwise decode using the dictionary. decode(_, Mod, #diameter_packet{header = Hdr} = Pkt) -> #diameter_header{cmd_code = CmdCode, is_request = IsRequest, is_error = IsError} = Hdr, MsgName = if IsError andalso not IsRequest -> 'answer-message'; true -> Mod:msg_name(CmdCode, IsRequest) end, decode_avps(MsgName, Mod, Pkt, collect_avps(Pkt)); decode(Id, Mod, Bin) when is_bitstring(Bin) -> decode(Id, Mod, #diameter_packet{header = decode_header(Bin), bin = Bin}). decode_avps(MsgName, Mod, Pkt, {E, Avps}) -> ?LOG(invalid, Pkt#diameter_packet.bin), #diameter_packet{errors = Failed} = P = decode_avps(MsgName, Mod, Pkt, Avps), P#diameter_packet{errors = [E | Failed]}; decode_avps('', Mod, Pkt, Avps) -> %% unknown message ... ?LOG(unknown, {Mod, Pkt#diameter_packet.header}), Pkt#diameter_packet{avps = lists:reverse(Avps), errors = [3001]}; %% DIAMETER_COMMAND_UNSUPPORTED %% msg = undefined identifies this case. decode_avps(MsgName, Mod, Pkt, Avps) -> %% ... or not {Rec, As, Failed} = Mod:decode_avps(MsgName, Avps), ?LOGC([] /= Failed, failed, {Mod, Failed}), Pkt#diameter_packet{msg = Rec, errors = Failed, avps = As}. %%% --------------------------------------------------------------------------- %%% # decode_header/1 %%% --------------------------------------------------------------------------- decode_header(<>) -> <> = CmdFlags, %% 3588 (ch 3) says that reserved bits MUST be set to 0 and ignored %% by the receiver. %% The RFC is quite unclear about the order of the bits in this %% case. It writes %% %% 0 1 2 3 4 5 6 7 %% +-+-+-+-+-+-+-+-+ %% |R P E T r r r r| %% +-+-+-+-+-+-+-+-+ %% %% in defining these but the scale refers to the (big endian) %% transmission order, first to last, not the bit order. That is, %% R is the high order bit. It's odd that a standard reserves %% low-order bit rather than high-order ones. #diameter_header{version = Version, length = MsgLength, cmd_code = CmdCode, application_id = ApplicationId, hop_by_hop_id = HopByHopId, end_to_end_id = EndToEndId, is_request = 1 == R, is_proxiable = 1 == P, is_error = 1 == E, is_retransmitted = 1 == T}; decode_header(_) -> false. %%% --------------------------------------------------------------------------- %%% # sequence_numbers/1 %%% --------------------------------------------------------------------------- %% The End-To-End identifier must be unique for at least 4 minutes. We %% maintain a 24-bit wraparound counter, and add an 8-bit persistent %% wraparound counter. The 8-bit counter is incremented each time the %% system is restarted. sequence_numbers({_,_} = T) -> T; sequence_numbers(#diameter_packet{bin = Bin}) when is_binary(Bin) -> sequence_numbers(Bin); sequence_numbers(#diameter_packet{header = #diameter_header{} = H}) -> sequence_numbers(H); sequence_numbers(#diameter_header{hop_by_hop_id = H, end_to_end_id = E}) -> {H,E}; sequence_numbers(<<_:12/binary, H:32, E:32, _/binary>>) -> {H,E}. %%% --------------------------------------------------------------------------- %%% # hop_by_hop_id/2 %%% --------------------------------------------------------------------------- hop_by_hop_id(Id, <>) -> <>. %%% --------------------------------------------------------------------------- %%% # msg_name/2 %%% --------------------------------------------------------------------------- msg_name(Dict0, #diameter_header{application_id = ?APP_ID_COMMON, cmd_code = C, is_request = R}) -> Dict0:msg_name(C,R); msg_name(_, Hdr) -> msg_id(Hdr). %% Note that messages in different applications could have the same %% name. %%% --------------------------------------------------------------------------- %%% # msg_id/1 %%% --------------------------------------------------------------------------- msg_id(#diameter_packet{msg = [#diameter_header{} = Hdr | _]}) -> msg_id(Hdr); msg_id(#diameter_packet{header = #diameter_header{} = Hdr}) -> msg_id(Hdr); msg_id(#diameter_header{application_id = A, cmd_code = C, is_request = R}) -> {A, C, if R -> 1; true -> 0 end}; msg_id(<<_:32, Rbit:1, _:7, CmdCode:24, ApplId:32, _/bitstring>>) -> {ApplId, CmdCode, Rbit}. %%% --------------------------------------------------------------------------- %%% # collect_avps/1 %%% --------------------------------------------------------------------------- %% Note that the returned list of AVP's is reversed relative to their %% order in the binary. Note also that grouped avp's aren't unraveled, %% only those at the top level. collect_avps(#diameter_packet{bin = Bin}) -> <<_:20/binary, Avps/bitstring>> = Bin, collect_avps(Avps); collect_avps(Bin) -> collect_avps(Bin, 0, []). collect_avps(<<>>, _, Acc) -> Acc; collect_avps(Bin, N, Acc) -> try split_avp(Bin) of {Rest, AVP} -> collect_avps(Rest, N+1, [AVP#diameter_avp{index = N} | Acc]) catch ?FAILURE(Error) -> {Error, Acc} end. %% 0 1 2 3 %% 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 %% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ %% | AVP Code | %% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ %% |V M P r r r r r| AVP Length | %% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ %% | Vendor-ID (opt) | %% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ %% | Data ... %% +-+-+-+-+-+-+-+-+ %% split_avp/1 split_avp(Bin) -> {Code, V, M, P, Len, HdrLen} = split_head(Bin), {Data, B} = split_data(Bin, HdrLen, Len - HdrLen), {B, #diameter_avp{code = Code, vendor_id = V, is_mandatory = 1 == M, need_encryption = 1 == P, data = Data}}. %% split_head/1 split_head(<>) -> {Code, V, M, P, Len, 12}; split_head(<>) -> {Code, undefined, M, P, Len, 8}; split_head(Bin) -> ?THROW({5014, #diameter_avp{data = Bin}}). %% 3588: %% %% DIAMETER_INVALID_AVP_LENGTH 5014 %% The request contained an AVP with an invalid length. A Diameter %% message indicating this error MUST include the offending AVPs %% within a Failed-AVP AVP. %% 6733: %% %% DIAMETER_INVALID_AVP_LENGTH 5014 %% %% The request contained an AVP with an invalid length. A Diameter %% message indicating this error MUST include the offending AVPs %% within a Failed-AVP AVP. In cases where the erroneous AVP length %% value exceeds the message length or is less than the minimum AVP %% ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ %% header length, it is sufficient to include the offending AVP %% ^^^^^^^^^^^^^ %% header and a zero filled payload of the minimum required length %% for the payloads data type. If the AVP is a Grouped AVP, the %% Grouped AVP header with an empty payload would be sufficient to %% indicate the offending AVP. In the case where the offending AVP %% header cannot be fully decoded when the AVP length is less than %% the minimum AVP header length, it is sufficient to include an %% offending AVP header that is formulated by padding the incomplete %% AVP header with zero up to the minimum AVP header length. %% %% The underlined clause must be in error since (1) a header less than %% the minimum value mean we don't know the identity of the AVP and %% (2) the last sentence covers this case. %% split_data/3 split_data(Bin, HdrLen, Len) when 0 =< Len -> split_data(Bin, HdrLen, Len, (4 - (Len rem 4)) rem 4); split_data(_, _, _) -> invalid_avp_length(). %% split_data/4 split_data(Bin, HdrLen, Len, Pad) -> <<_:HdrLen/binary, T/bitstring>> = Bin, case T of <> -> {Data, Rest}; _ -> invalid_avp_length() end. %% invalid_avp_length/0 %% %% AVP Length doesn't mesh with payload. Induce a decode error by %% returning a payload that no valid Diameter type can have. This is %% so that a known AVP will result in 5014 error with a zero'd %% payload. Here we simply don't know how to construct this payload. %% (Yes, this solution is an afterthought.) invalid_avp_length() -> {<<0:1>>, <<>>}. %%% --------------------------------------------------------------------------- %%% # pack_avp/1 %%% --------------------------------------------------------------------------- %% The normal case here is data as an #diameter_avp{} list or an %% iolist, which are the cases that generated codec modules use. The %% other case is as a convenience in the relay case in which the %% dictionary doesn't know about specific AVP's. %% Grouped AVP whose components need packing ... pack_avp(#diameter_avp{data = [#diameter_avp{} | _] = Avps} = A) -> pack_avp(A#diameter_avp{data = encode_avps(Avps)}); %% ... data as a type/value tuple ... pack_avp(#diameter_avp{data = {Type, Value}} = A) when is_atom(Type) -> pack_avp(A#diameter_avp{data = diameter_types:Type(encode, Value)}); %% ... with a header in various forms ... pack_avp(#diameter_avp{data = {{_,_,_} = T, {Type, Value}}}) -> pack_avp(T, iolist_to_binary(diameter_types:Type(encode, Value))); pack_avp(#diameter_avp{data = {{_,_,_} = T, Bin}}) when is_binary(Bin) -> pack_avp(T, Bin); pack_avp(#diameter_avp{data = {Dict, Name, Value}} = A) -> {Code, _Flags, Vid} = Hdr = Dict:avp_header(Name), {Name, Type} = Dict:avp_name(Code, Vid), pack_avp(A#diameter_avp{data = {Hdr, {Type, Value}}}); pack_avp(#diameter_avp{code = undefined, data = Bin}) when is_binary(Bin) -> %% Reset the AVP Length of an AVP Header resulting from a 5014 %% error. The RFC doesn't explicitly say to do this but the %% receiver can't correctly extract this and following AVP's %% without a correct length. On the downside, the header doesn't %% reveal if the received header has been padded. Pad = 8*header_length(Bin) - bit_size(Bin), Len = size(<> = <>), <>; %% ... or as an iolist. pack_avp(#diameter_avp{code = Code, vendor_id = V, is_mandatory = M, need_encryption = P, data = Data}) -> Flags = lists:foldl(fun flag_avp/2, 0, [{V /= undefined, 2#10000000}, {M, 2#01000000}, {P, 2#00100000}]), pack_avp({Code, Flags, V}, iolist_to_binary(Data)). header_length(<<_:32, 1:1, _/bitstring>>) -> 12; header_length(_) -> 8. flag_avp({true, B}, F) -> F bor B; flag_avp({false, _}, F) -> F. %%% --------------------------------------------------------------------------- %%% # pack_avp/2 %%% --------------------------------------------------------------------------- pack_avp({Code, Flags, VendorId}, Bin) when is_binary(Bin) -> Sz = size(Bin), pack_avp(Code, Flags, VendorId, Sz, pad(Sz rem 4, Bin)). pad(0, Bin) -> Bin; pad(N, Bin) -> P = 8*(4-N), <>. %% Note that padding is not included in the length field as mandated by %% the RFC. %% pack_avp/5 %% %% Prepend the vendor id as required. pack_avp(Code, Flags, Vid, Sz, Bin) when 0 == Flags band 2#10000000 -> undefined = Vid, %% sanity check pack_avp(Code, Flags, Sz, Bin); pack_avp(Code, Flags, Vid, Sz, Bin) -> pack_avp(Code, Flags, Sz+4, <>). %% pack_avp/4 pack_avp(Code, Flags, Sz, Bin) -> Length = Sz + 8, <>.