user_message_reference/tag values not decoding properly

[archseer]

This deliver_sm packet has a user_message_reference optional value.

 └─ λ xxd raw.bin
00000000: 0000 004a 0000 0005 0000 0000 2710 150e  ...J........'...
00000010: 0001 0131 3231 3233 3435 3637 3839 0001  ...12123456789..
00000020: 0131 3233 3435 3637 3839 3031 0000 0000  .12345678901....
00000030: 0000 0000 0300 0d4d 6f72 6520 6d65 7373  .......More mess
00000040: 6167 6573 0204 0002 004d                 ages.....M

But when decoding, it's returned as 516 (0x0204 = user_message_reference) in the optional map, instead of decoded properly.

iex(13)> v = File.read!("raw.bin")
<<0, 0, 0, 74, 0, 0, 0, 5, 0, 0, 0, 0, 39, 16, 21, 14, 0, 1, 1, 49, 50, 49, 50,
  51, 52, 53, 54, 55, 56, 57, 0, 1, 1, 49, 50, 51, 52, 53, 54, 55, 56, 57, 48,
  49, 0, 0, 0, 0, 0, 0, ...>>
iex(14)> SMPPEX.Protocol.parse(v)
{:ok,
 {:pdu,
  %SMPPEX.Pdu{command_id: 5, command_status: 0,
   mandatory: %{data_coding: 3, dest_addr_npi: 1, dest_addr_ton: 1,
     destination_addr: "12345678901", esm_class: 0, priority_flag: 0,
     protocol_id: 0, registered_delivery: 0, replace_if_present_flag: 0,
     schedule_delivery_time: "", service_type: "",
     short_message: "More messages", sm_default_msg_id: 0, sm_length: 13,
     source_addr: "12123456789", source_addr_npi: 1, source_addr_ton: 1,
     validity_period: ""}, optional: %{516 => 77},
   ref: #Reference<0.0.262145.195893>, sequence_number: 655365390}}, ""}

Meanwhile, Wireshark does correctly parse it:

[archseer]

Ah unless that is by design? The TLV parser doesn't seem to use the tag ID. It was just surprising since all the other keys were atoms.

[savonarola]

Hello!

Although parsed optional fields are stored by ids, one can still access them by name:

iex(1)> pdu = %SMPPEX.Pdu{command_id: 5, command_status: 0,
...(1)>    mandatory: %{data_coding: 3, dest_addr_npi: 1, dest_addr_ton: 1,
...(1)>      destination_addr: "12345678901", esm_class: 0, priority_flag: 0,
...(1)>      protocol_id: 0, registered_delivery: 0, replace_if_present_flag: 0,
...(1)>      schedule_delivery_time: "", service_type: "",
...(1)>      short_message: "More messages", sm_default_msg_id: 0, sm_length: 13,
...(1)>      source_addr: "12123456789", source_addr_npi: 1, source_addr_ton: 1,
...(1)>      validity_period: ""}, optional: %{516 => 77}
...(1)> }
%SMPPEX.Pdu{command_id: 5, command_status: 0,
 mandatory: %{data_coding: 3, dest_addr_npi: 1, dest_addr_ton: 1,
   destination_addr: "12345678901", esm_class: 0, priority_flag: 0,
   protocol_id: 0, registered_delivery: 0, replace_if_present_flag: 0,
   schedule_delivery_time: "", service_type: "", short_message: "More messages",
   sm_default_msg_id: 0, sm_length: 13, source_addr: "12123456789",
   source_addr_npi: 1, source_addr_ton: 1, validity_period: ""},
 optional: %{516 => 77}, ref: nil, sequence_number: 0}
iex(2)> SMPPEX.Pdu.optional_field(pdu, :user_message_reference)
77