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Diffstat (limited to 'lib/diameter/src/app/diameter_codec.erl')
| -rw-r--r-- | lib/diameter/src/app/diameter_codec.erl | 561 |
1 files changed, 561 insertions, 0 deletions
diff --git a/lib/diameter/src/app/diameter_codec.erl b/lib/diameter/src/app/diameter_codec.erl new file mode 100644 index 0000000000..d88f42fb7c --- /dev/null +++ b/lib/diameter/src/app/diameter_codec.erl @@ -0,0 +1,561 @@ +%% +%% %CopyrightBegin% +%% +%% Copyright Ericsson AB 2010-2011. 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/1, + 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 rather than letting the emulator truncate the + %% error report. + X = {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{bin = <<Vsn:8, Length:24, + Flags:8, Code:24, + Aid:32, + Hid:32, + Eid:32, + Avps/binary>>}; + +e(Mod0, #diameter_packet{header = Hdr, msg = Msg} = Pkt) -> + #diameter_header{version = Vsn, + hop_by_hop_id = Hid, + end_to_end_id = Eid} + = Hdr, + + {Mod, MsgName} = rec2msg(Mod0, 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 = <<Vsn:8, Length:24, + Flags:8, Code:24, + Aid:32, + Hid:32, + Eid:32, + Avps/binary>>}. + +%% 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, MsgName, Header) -> + {Code, Flags, ApplId} = h(Mod, MsgName, Header), + {Code, p(Flags, Header), ApplId}. + +%% 6.2 of 3588 requires the same 'P' bit on an answer as on the +%% request. + +p(Flags, #diameter_header{is_request = true, + is_proxiable = P}) -> + Flags band (2#10110000 bor choose(P, 2#01000000, 0)); +p(Flags, _) -> + Flags. + +h(Mod, 'answer-message' = MsgName, Header) -> + ?BASE = Mod, + #diameter_header{cmd_code = Code} = Header, + {_, Flags, ApplId} = ?BASE:msg_header(MsgName), + {Code, Flags, ApplId}; + +h(Mod, MsgName, _) -> + Mod:msg_header(MsgName). + +%% rec2msg/2 + +rec2msg(_, ['answer-message' = M | _]) -> + {?BASE, M}; + +rec2msg(Mod, [MsgName|_]) + when is_atom(MsgName) -> + {Mod, MsgName}; + +rec2msg(Mod, Rec) -> + R = element(1, Rec), + A = 'answer-message', + case ?BASE:msg2rec(A) of + R -> + {?BASE, A}; + _ -> + {Mod, Mod:rec2msg(R)} + end. + +%%% --------------------------------------------------------------------------- +%%% # 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 + {Bs, As} -> + Pkt#diameter_packet{avps = As, + errors = [Bs]}; + As -> + Pkt#diameter_packet{avps = As} + end; + +%% Otherwise decode using the dictionary. +decode(_, Mod, #diameter_packet{header = Hdr} = Pkt) + when is_atom(Mod) -> + #diameter_header{cmd_code = CmdCode, + is_request = IsRequest, + is_error = IsError} + = Hdr, + + {M, MsgName} = if IsError andalso not IsRequest -> + {?BASE, 'answer-message'}; + true -> + {Mod, Mod:msg_name(CmdCode, IsRequest)} + end, + + decode_avps(MsgName, M, 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, {Bs, Avps}) -> %% invalid avp bits ... + ?LOG(invalid, Pkt#diameter_packet.bin), + #diameter_packet{errors = Failed} + = P + = decode_avps(MsgName, Mod, Pkt, Avps), + P#diameter_packet{errors = [Bs | 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(<<Version:8, + MsgLength:24, + CmdFlags:1/binary, + CmdCode:24, + ApplicationId:32, + HopByHopId:32, + EndToEndId:32, + _/bitstring>>) -> + <<R:1, P:1, E:1, T:1, _:4>> + = 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(#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, <<H:12/binary, _:32, T/binary>>) -> + <<H/binary, Id:32, T/binary>>. + +%%% --------------------------------------------------------------------------- +%%% # msg_name/1 +%%% --------------------------------------------------------------------------- + +msg_name(#diameter_header{application_id = ?APP_ID_COMMON, + cmd_code = C, + is_request = R}) -> + ?BASE: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(_) -> + {Bin, 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) -> + 8 =< size(Bin) orelse ?THROW(truncated_header), + + <<Code:32, Flags:1/binary, Length:24, Rest/bitstring>> + = Bin, + + DataSize = Length - 8, % size(Code+Flags+Length) = 8 octets + PadSize = (4 - (DataSize rem 4)) rem 4, + + DataSize + PadSize =< size(Rest) + orelse ?THROW(truncated_data), + + <<Data:DataSize/binary, _:PadSize/binary, R/bitstring>> + = Rest, + <<Vbit:1, Mbit:1, Pbit:1, _Reserved:5>> + = Flags, + + 0 == Vbit orelse 4 =< size(Data) + orelse ?THROW(truncated_vendor_id), + + {Vid, D} = vid(Vbit, Data), + {R, #diameter_avp{code = Code, + vendor_id = Vid, + is_mandatory = 1 == Mbit, + need_encryption = 1 == Pbit, + data = D}}. + +%% The RFC is a little misleading when stating that OctetString is +%% padded to a 32-bit boundary while other types align naturally. All +%% other types are already multiples of 32 bits so there's no need to +%% distinguish between types here. Any invalid lengths will result in +%% decode error in diameter_types. + +vid(1, <<Vid:32, Data/bitstring>>) -> + {Vid, Data}; +vid(0, Data) -> + {undefined, Data}. + +%%% --------------------------------------------------------------------------- +%%% # 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, possibly with header data, ... +pack_avp(#diameter_avp{data = {Type, Value}} = A) + when is_atom(Type) -> + pack_avp(A#diameter_avp{data = diameter_types:Type(encode, Value)}); +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}}}); + +%% ... 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)). + +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), + <<Bin/binary, 0:P>>. +%% 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, <<Vid:32, Bin/binary>>). + +%% pack_avp/4 + +pack_avp(Code, Flags, Sz, Bin) -> + Length = Sz + 8, + <<Code:32, Flags:8, Length:24, Bin/binary>>. + +%% =========================================================================== + +choose(true, X, _) -> X; +choose(false, _, X) -> X. |