MAP: Fix-up after asn1ct automatic 1990->1994 EXTERNAL conversion
So what the Erlang asn1ct does is: Decode the incoming EXTERNAL type, convert it to the 1994 format and hand it to the user program. The encoder is opposite: Take what the user supplies (in our case 1994) and then transform it to 1990 before handing it to the actual encoder function. The only problem is: The 1994 format does only support OCTET STRING as actual embedded data type, whereas the 1990 format can also indicate 'singla-asn1-type', i.e. a constructed type. So since that information is already lost before we ever get the record from the Erlang asn1 decoder, it will be re-encoded as OCTET STRING :( Until this is fixed in the asn1ct/asn1rt code, we have to use this workaround...
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@ -19,7 +19,7 @@
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-module(map_codec).
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-author('Harald Welte <laforge@gnumonks.org>').
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%-include("map.hrl").
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-include("map.hrl").
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-include_lib("osmo_ss7/include/isup.hrl").
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-export([parse_tcap_msg/1, encode_tcap_msg/1]).
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@ -117,11 +117,31 @@ parse_tcap_msg(MsgBin) when is_binary(MsgBin) ->
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parse_tcap_msg(Msg) when is_list(Msg) ->
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case asn1rt:decode('map', 'MapSpecificPDUs', Msg) of
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{ok, {Type, TcapMsgDec}} ->
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{Type, TcapMsgDec};
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fixup_dialogue({Type, TcapMsgDec});
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Error ->
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Error
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end.
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% Extract the dialoguePortion and feed it through external_1990ify/1
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fixup_dialogue({'begin', Beg = #'MapSpecificPDUs_begin'{dialoguePortion=Dia}}) ->
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{'begin', Beg#'MapSpecificPDUs_begin'{dialoguePortion = external_1990ify(Dia)}};
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fixup_dialogue({'end', Beg = #'MapSpecificPDUs_end'{dialoguePortion=Dia}}) ->
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{'end', Beg#'MapSpecificPDUs_end'{dialoguePortion = external_1990ify(Dia)}};
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fixup_dialogue({'continue', Beg = #'MapSpecificPDUs_continue'{dialoguePortion=Dia}}) ->
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{'continue', Beg#'MapSpecificPDUs_continue'{dialoguePortion = external_1990ify(Dia)}};
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fixup_dialogue({'unidirectional', Beg = #'MapSpecificPDUs_unidirectional'{dialoguePortion=Dia}}) ->
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{'unidirectional', Beg#'MapSpecificPDUs_unidirectional'{dialoguePortion = external_1990ify(Dia)}};
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fixup_dialogue(Default) ->
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Default.
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% Take the EXTERNAL date type and convert from 1994-style to 1990 with 'single-ASN1-type'
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external_1990ify({'EXTERNAL', {syntax, DirRef}, IndirRef, Data}) when is_list(Data); is_binary(Data) ->
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#'EXTERNAL'{'direct-reference' = DirRef,
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'indirect-reference' = IndirRef,
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encoding = {'single-ASN1-type', Data}};
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external_1990ify(Default) ->
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Default.
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encode_tcap_msg({Type, TcapMsgDec}) ->
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case asn1rt:encode('map', 'MapSpecificPDUs', {Type, TcapMsgDec}) of
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{ok, List} ->
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@ -26,13 +26,12 @@
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-define(_assertEqualArgs(Expect, Expr, Args), ?_test(?assertEqual(Expect, Expr, Args))).
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-define(TCAP_MSG_BIN, <<100,65,73,4,81,1,2,200,107,42,40,40,6,7,0,17,134,5,1,1,1,160,29,97,27,128,2,7,128,161,9,6,7,4,0,0,1,0,1,3,162,3,2,1,0,163,5,161,3,2,1,0,108,13,163,11,2,1,64,2,1,8,48,3,10,1,0>>).
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-define(TCAP_MSG_DEC, {'end',{'MapSpecificPDUs_end',[81,1,2,200],{'EXTERNAL',{syntax,{0,0,17,773,1,1,1}},asn1_NOVALUE,[97,27,128,2,7,128,161,9,6,7,4,0,0,1,0,1,3,162,3,2,1,0,163,5,161,3,2,1,0]},[{basicROS,{returnError,{'MapSpecificPDUs_end_components_SEQOF_basicROS_returnError',{present,64},{local,8},{'RoamingNotAllowedParam',plmnRoamingNotAllowed,asn1_NOVALUE,asn1_NOVALUE}}}}]}}).
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-define(TCAP_MSG_DEC, {'end',{'MapSpecificPDUs_end',[81,1,2,200],{'EXTERNAL',{0,0,17,773,1,1,1},asn1_NOVALUE,asn1_NOVALUE, {'single-ASN1-type', [97,27,128,2,7,128,161,9,6,7,4,0,0,1,0,1,3,162,3,2,1,0,163,5,161,3,2,1,0]}},[{basicROS,{returnError,{'MapSpecificPDUs_end_components_SEQOF_basicROS_returnError',{present,64},{local,8},{'RoamingNotAllowedParam',plmnRoamingNotAllowed,asn1_NOVALUE,asn1_NOVALUE}}}}]}}).
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parse_test() ->
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?assertEqual(?TCAP_MSG_DEC, map_codec:parse_tcap_msg(?TCAP_MSG_BIN)).
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% BER allows for different binary encodings of each message, the test below is not valid
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%encode_test() ->
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% ?assertEqual(?TCAP_MSG_BIN, map_codec:encode_tcap_msg(?TCAP_MSG_DEC)).
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encode_test() ->
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?assertEqual(?TCAP_MSG_BIN, map_codec:encode_tcap_msg(?TCAP_MSG_DEC)).
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-define(ADDR_DEC, #party_number{nature_of_addr_ind = ?ISUP_ADDR_NAT_INTERNATIONAL,
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internal_net_num = undefined,
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@ -109,12 +108,14 @@ handle_sccp(S = #sccp_msg{msg_type = ?SCCP_MSGT_UDT, parameters = Params}, Path)
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?debugFmt("Path: ~p~nMAP Decode Error: ~w~n", [PathOut, ErrTuple]),
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erlang:error(ErrTuple);
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MapDec ->
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%?debugFmt("~w~n", [MapDec]),
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case map_codec:encode_tcap_msg(MapDec) of
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{error, Error} ->
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ErrTuple = {Error, erlang:get_stacktrace(), [{map_dec, MapDec}]},
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?debugFmt("Path: ~p~nMAP Encode Error: ~w~n", [PathOut, ErrTuple]),
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erlang:error(ErrTuple);
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MapReenc ->
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%?assertEqualArgs(UserData, MapReenc, [{layer, map}, {path, Path}]),
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MapReencDec = map_codec:parse_tcap_msg(MapReenc),
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?assertEqualArgs(MapDec, MapReencDec, [{layer, map}, {path, Path}])
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end
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