Error on encoding TCAP message with invoke component without linkedId #23
Comments
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sorry I completely missed this one. I've confirmed that I'm too see this one. |
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Unfortunately, I was unable to test your solution at this time. However, here is the modification that worked for me: |
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I've checked a bit more, and it seems Wireshark ASN.1 implementation differs and generates this issue. GSM-ASN.1 is from prior to ASN.1-spec removed support of macros, so everyone who are implementing this will have to modify the specification for it to work. The original ITU-T X.880 ASN.1 defines the following for Invoke Invoke{InvokeId:InvokeIdSet, OPERATION]:Operations} ::= SEQUENCE {
invokeId
InvokeId(InvokeIdSet)
(CONSTRAINED BY { -- must be unambiguous --} !
RejectProblem,
linkedId
CHOICE {present [0] IMPLICIT present < InvokeId,
absent [1] IMPLICIT NULL
}
(CONSTRAINED BY { -- must identify an outstanding operation --} !
RejectProblem:invoke-unrecognizedLinkedId)
(CONSTRAINED BY { -- which has one or more linked operations--} !
RejectProblem OPTIONAL,
opcode
OPERATION.&operationCode
({Operations} !RejectProblem:invoke-unrecognizedOperation),
argument
OPERATION.&ArgumentType
({Operations}{@opcode} !RejectProblem OPTIONAL
}
(CONSTRAINED BY { -- must conform to the above definition --} !
RejectProblem
(WITH COMPONENTS {
...,
linkedId ABSENT
} |
WITH COMPONENTS {
...,
linkedId PRESENT,
opcode (CONSTRAINED BY { -- must be in the &Linked field of the associated operation --
} !RejectProblem:invoke-unexpectedLinkedOperation)
})
InvokeId ::= CHOICE {present INTEGER,
absent NULL
}What Wireshark has done in this regard is to remove absent-type, and remove the implicit tags. Invoke ::= SEQUENCE {
invokeID InvokeIdType,
linkedID [0] InvokeIdType OPTIONAL,
opCode MAP-OPERATION,
invokeparameter InvokeParameter OPTIONAL
}
InvokeIdType ::= INTEGER (-128..127)Which is much different from original and from OTC implementation. Invoke ::= SEQUENCE
{
invokeId InvokeId,
linkedId CHOICE {
present [0] IMPLICIT present < InvokeId,
absent [1] IMPLICIT NULL
} OPTIONAL,
opcode Code,
argument ANY DEFINED BY opcode OPTIONAL
}
InvokeId ::= CHOICE
{
present INTEGER,
absent NULL
}I think this is a bug in the wireshark dissector, and you should raise a bug-report there. Because absent is allowed on the wire. BTW I created a function to write a payload to pcap, it can be used in the following way. MAPBin = <<48,19,160,9,128,7,1,2,3,4,5,6,7,161,0,131,4,9,8,7,6>>,
M3ua = #{protocol => m3ua,
message_type => data,
message_class => transfer,
protocol_data =>
#{service_indicator => sccp,
originating_point_code => <<0,0,5,4>>,
destination_point_code => <<0,0,53,167>>,
network_indicator => national_spare,
message_priority => 0,
signalling_link_selection => 8}},
Sccp = #{protocol => sccp,
message_type => xudt,
called_party_address =>
#{subsystem_number => msc,
routing_indicator => global_title,
global_title =>
#{address => "46777777777",
nature_of_address_indicator => 4,
numbering_plan => 1,
translation_type => 0,
odd_even_indicator => odd,
encoding_scheme => bcd},
national_use_indicator => false,
point_code => undefined},
calling_party_address =>
#{subsystem_number => msc,
routing_indicator => global_title,
global_title =>
#{address => "46777777777",
nature_of_address_indicator => 4,
numbering_plan => 1,
translation_type => 0,
odd_even_indicator => odd,
encoding_scheme => bcd},
national_use_indicator => false,
point_code => undefined},
protocol_class => #{options => return_on_error,class => 0},
hop_counter => 15},
InvokeComponent = #{
component_type => invoke,
invokeId => 0,
opcode => {local, 71},
argument => MAPBin
},
Tcap = #{dialogue =>
#{type => dialogueRequest,
application_context_family => map,
user_information => undefined,
application_context_name => 'anyTimeInfoEnquiryContext-v3',
supported_versions => [version1]},
otid => <<"000001B3">>,
components =>
[InvokeComponent],
type => 'begin'},
TcapBin = otc_tcap:encode(Tcap),
{ok, M3uaPkt} = otc:encode({[M3ua, Sccp], TcapBin}),
otc_util:write_to_pcap("test.pcap", M3uaPkt). |
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Sorry for the late reply; I missed your answer. Thank you very much for your detailed explanation. |
Thanks for the great library, I've tried to encode the following tcap:map message, but I got some error. Here is the snippet:
{ok, Arg} = file:read_file("/home/ali/arg.bin"), Map = #{ operation => anyTimeInterrogation, component_type => invoke, invokeId => 0, opcode => {local, 71}, argument => Arg }, Tcap = #{ protocol => tcap, otid => <<"000001B3">>, type => 'begin', dialogue => #{ type => dialogueRequest, application_context_family => map, user_information => undefined, application_context_name => 'anyTimeInfoEnquiryContext-v3', supported_versions => [version1] } }, {ok, TcapBin} = otc:encode({Tcap, [Map]}),And here is the error message:
I've modified the
compose_invoke_idfunction to return a tuple if linked_id is not set, but wireshark claims that the packet is malformed. Here is the change that I've made inotc_tcap.erl:The text was updated successfully, but these errors were encountered: