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/* packet-ems.c
* EGNOS Message Server file format dissection.
*
* By Timo Warns <timo.warns@gmail.com>
* Copyright 2023 Timo Warns
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@unicom.net>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <wiretap/wtap.h>
/*
* Dissects PCAPs mapped from the EMS file format as defined by the "EGNOS
* Messager Server User Interface Document" (E-RD-SYS-E31-011-ESA, Issue 2)
*/
/* Initialize the protocol and registered fields */
static int proto_ems;
static int hf_ems_prn;
static int hf_ems_year;
static int hf_ems_month;
static int hf_ems_day;
static int hf_ems_hour;
static int hf_ems_minute;
static int hf_ems_second;
static int hf_ems_mt;
static int ett_ems;
static dissector_handle_t ems_handle;
/* Dissect EMS data record */
static int dissect_ems(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_) {
tvbuff_t *next_tvb;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "EMS");
col_clear(pinfo->cinfo, COL_INFO);
uint8_t prn, year, month, day, hour, minute, second, mt;
prn = tvb_get_uint8(tvb, 0);
year = tvb_get_uint8(tvb, 1);
month = tvb_get_uint8(tvb, 2);
day = tvb_get_uint8(tvb, 3);
hour = tvb_get_uint8(tvb, 4);
minute = tvb_get_uint8(tvb, 5);
second = tvb_get_uint8(tvb, 6);
mt = tvb_get_uint8(tvb, 7);
proto_tree *ems_tree = proto_tree_add_subtree_format(tree, tvb, 0, 40,
ett_ems, NULL, "EMS (%04d-%02d-%02d %02d:%02d:%02d PRN%d MT%d)",
2000 + year, month, day, hour, minute, second, prn, mt);
proto_tree_add_item(ems_tree, hf_ems_prn, tvb, 0, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(ems_tree, hf_ems_year, tvb, 1, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(ems_tree, hf_ems_month, tvb, 2, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(ems_tree, hf_ems_day, tvb, 3, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(ems_tree, hf_ems_hour, tvb, 4, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(ems_tree, hf_ems_minute, tvb, 5, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(ems_tree, hf_ems_second, tvb, 6, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(ems_tree, hf_ems_mt, tvb, 7, 1, ENC_BIG_ENDIAN);
next_tvb = tvb_new_subset_remaining(tvb, 8);
dissector_handle_t sbas_l1_dissector_handle = find_dissector("sbas_l1");
if (sbas_l1_dissector_handle) {
call_dissector(sbas_l1_dissector_handle, next_tvb, pinfo, tree);
}
else {
call_data_dissector(next_tvb, pinfo, tree);
}
return tvb_captured_length(tvb);
}
void proto_register_ems(void) {
static hf_register_info hf[] = {
{&hf_ems_prn, {"PRN", "ems.prn", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{&hf_ems_year, {"Year", "ems.year", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{&hf_ems_month, {"Month", "ems.month", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{&hf_ems_day, {"Day", "ems.day", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{&hf_ems_hour, {"Hour", "ems.hour", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{&hf_ems_minute, {"Minute", "ems.minute", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{&hf_ems_second, {"Second", "ems.second", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{&hf_ems_mt, {"Message Type", "ems.mt", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
};
static int *ett[] = {
&ett_ems,
};
proto_ems = proto_register_protocol("EGNOS Message Server file", "EMS", "ems");
ems_handle = register_dissector("ems", dissect_ems, proto_ems);
proto_register_field_array(proto_ems, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
}
void proto_reg_handoff_ems(void) {
static bool initialized = false;
if (!initialized) {
dissector_add_uint("wtap_encap", WTAP_ENCAP_EMS, ems_handle);
}
}
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