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MAC-NR: add BCCH BCH decoding 

Change-Id: I7a3b99ce99c8589286a6e99728e809a9c9475977
Reviewed-on: https://code.wireshark.org/review/26519
Reviewed-by: Pascal Quantin <pascal.quantin@gmail.com>
This commit is contained in:
Pascal Quantin 2018-03-17 11:25:39 +01:00
parent 07db1e95be
commit 46819c88af
1 changed files with 100 additions and 5 deletions
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105
epan/dissectors/packet-mac-nr.c
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@ -37,6 +37,8 @@ static int hf_mac_nr_context_direction = -1;
static int hf_mac_nr_context_rnti = -1;
static int hf_mac_nr_context_rnti_type = -1;
static int hf_mac_nr_context_ueid = -1;
static int hf_mac_nr_context_bcch_transport_channel = -1;
static int hf_mac_nr_subheader = -1;
static int hf_mac_nr_subheader_reserved = -1;
@ -47,7 +49,7 @@ static int hf_mac_nr_ulsch_lcid = -1;
static int hf_mac_nr_dlsch_lcid = -1;
static int hf_mac_nr_dlsch_sdu = -1;
static int hf_mac_nr_ulsch_sdu = -1;
static int hf_mac_nr_bcch_pdu = -1;
static int hf_mac_nr_control_crnti = -1;
static int hf_mac_nr_control_ue_contention_resolution_identity = -1;
@ -139,6 +141,11 @@ static int ett_mac_nr_rar_subheader = -1;
static expert_field ei_mac_nr_no_per_frame_data = EI_INIT;
static dissector_handle_t nr_rrc_bcch_bch_handle;
/* By default try to decode transparent data (BCCH, PCCH and CCCH) data using NR RRC dissector */
static gboolean global_mac_nr_attempt_rrc_decode = TRUE;
/* Constants and value strings */
static const value_string radio_type_vals[] =
@ -166,6 +173,13 @@ static const value_string rnti_type_vals[] =
{ 0, NULL }
};
static const value_string bcch_transport_channel_vals[] =
{
{ SI_RNTI, "DL-SCH"},
{ NO_RNTI, "BCH"},
{ 0, NULL }
};
#define DUPLICATION_ACTIVATION_DEACTIVATION_LCID 0x38
#define SCELL_ACTIVATION_DEACTIVATION_4 0x39
@ -480,7 +494,64 @@ static void write_pdu_label_and_info_literal(proto_item *ti1, proto_item *ti2,
}
}
static void
call_with_catch_all(dissector_handle_t handle, tvbuff_t* tvb, packet_info *pinfo, proto_tree *tree)
{
/* Call it (catch exceptions so that stats will be updated) */
if (handle) {
TRY {
call_dissector_only(handle, tvb, pinfo, tree, NULL);
}
CATCH_ALL {
}
ENDTRY
}
}
/* Dissect BCCH PDU */
static void dissect_bcch(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
proto_item *pdu_ti,
int offset, mac_nr_info *p_mac_nr_info)
{
proto_item *ti;
write_pdu_label_and_info(pdu_ti, NULL, pinfo,
"BCCH PDU (%u bytes, on %s transport) ",
tvb_reported_length_remaining(tvb, offset),
val_to_str_const(p_mac_nr_info->rntiType,
bcch_transport_channel_vals,
"Unknown"));
/* Show which transport layer it came in on (inferred from RNTI type) */
ti = proto_tree_add_uint(tree, hf_mac_nr_context_bcch_transport_channel,
tvb, offset, 0, p_mac_nr_info->rntiType);
PROTO_ITEM_SET_GENERATED(ti);
/****************************************/
/* Whole frame is BCCH data */
/* Raw data */
ti = proto_tree_add_item(tree, hf_mac_nr_bcch_pdu,
tvb, offset, -1, ENC_NA);
if (global_mac_nr_attempt_rrc_decode) {
/* Attempt to decode payload using NR RRC dissector */
dissector_handle_t protocol_handle;
tvbuff_t *rrc_tvb = tvb_new_subset_remaining(tvb, offset);
if (p_mac_nr_info->rntiType == NO_RNTI) {
protocol_handle = nr_rrc_bcch_bch_handle;
} else {
/* TODO: add handle once NR-RRC spec is updated */
protocol_handle = NULL;
}
/* Hide raw view of bytes */
PROTO_ITEM_SET_HIDDEN(ti);
call_with_catch_all(protocol_handle, rrc_tvb, pinfo, tree);
}
}
static void dissect_rar(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree,
proto_item *pdu_ti _U_, guint32 offset,
@ -1018,13 +1089,13 @@ static int dissect_mac_nr(tvbuff_t *tvb, packet_info *pinfo,
break;
case SI_RNTI:
/* BCH over DL-SCH */
// dissect_bch(tvb, pinfo, mac_nr_tree, pdu_ti, offset, p_mac_nr_info);
/* BCCH over DL-SCH */
dissect_bcch(tvb, pinfo, mac_nr_tree, pdu_ti, offset, p_mac_nr_info);
break;
case NO_RNTI:
/* Must be BCH over BCH... */
// dissect_bch(tvb, pinfo, mac_nr_tree, pdu_ti, offset, p_mac_nr_info);
/* Must be BCCH over BCH... */
dissect_bcch(tvb, pinfo, mac_nr_tree, pdu_ti, offset, p_mac_nr_info);
break;
@ -1170,6 +1241,12 @@ void proto_register_mac_nr(void)
"User Equipment Identifier associated with message", HFILL
}
},
{ &hf_mac_nr_context_bcch_transport_channel,
{ "Transport channel",
"mac-nr.bcch-transport-channel", FT_UINT8, BASE_DEC, VALS(bcch_transport_channel_vals), 0x0,
"Transport channel BCCH data was carried on", HFILL
}
},
{ &hf_mac_nr_subheader,
{ "Subheader",
@ -1225,6 +1302,12 @@ void proto_register_mac_nr(void)
NULL, HFILL
}
},
{ &hf_mac_nr_bcch_pdu,
{ "BCCH PDU",
"mac-nr.bcch.pdu", FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL
}
},
/*********************************/
@ -1714,6 +1797,7 @@ void proto_register_mac_nr(void)
{ &ei_mac_nr_no_per_frame_data, { "mac-nr.no_per_frame_data", PI_UNDECODED, PI_WARN, "Can't dissect NR MAC frame because no per-frame info was attached!", EXPFILL }},
};
module_t *mac_nr_module;
expert_module_t* expert_mac_nr;
/* Register protocol. */
@ -1725,12 +1809,23 @@ void proto_register_mac_nr(void)
/* Allow other dissectors to find this one by name. */
register_dissector("mac-nr", dissect_mac_nr, proto_mac_nr);
/* Preferences */
mac_nr_module = prefs_register_protocol(proto_mac_nr, NULL);
prefs_register_bool_preference(mac_nr_module, "attempt_rrc_decode",
"Attempt to decode BCCH, PCCH and CCCH data using NR RRC dissector",
"Attempt to decode BCCH, PCCH and CCCH data using NR RRC dissector",
&global_mac_nr_attempt_rrc_decode);
}
void proto_reg_handoff_mac_nr(void)
{
/* Add as a heuristic UDP dissector */
heur_dissector_add("udp", dissect_mac_nr_heur, "MAC-NR over UDP", "mac_nr_udp", proto_mac_nr, HEURISTIC_DISABLE);
nr_rrc_bcch_bch_handle = find_dissector_add_dependency("nr-rrc.bcch.bch", proto_mac_nr);
}