osmith
/
wireshark
forked from osmocom/wireshark
1
0
Fork 0
Code Pull Requests Releases Wiki Activity

WIP: gm: Decode GSM GM MS RA Capabilities IE with RLCMAC CSN1 decoder 

Tested with a sample pcap file containing an GSM GM packet (Attach
Request)  with an MS Radio Access Capabilities IE containing several entries.

TODO:
* Check if by dropping the ad-hoc decoder we lose support/features.
* Drop de_gmm_ms_radio_acc_cap and replace it with
  de_gmm_ms_radio_acc_cap_rlcmac(), since there are other users of that
  function in other protocol dissectors. Then all benefit from the
  change. More than 1k lines of code can be dropped.
* Some general clean up required

Change-Id: I096eafcb5ca31d0ad1fa63561f43853ee4e7a40f
This commit is contained in:
Pau Espin 2020-03-25 15:30:16 +01:00
parent 902531bd81
commit 3c341df6d2
2 changed files with 29 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
epan/dissectors/packet-gsm_a_gm.c
View File

@ -91,6 +91,7 @@
#include <epan/expert.h>
#include <epan/ipproto.h>
#include <epan/etypes.h>
#include "packet-gsm_rlcmac.h"
#include "packet-ber.h"
#include "packet-gsm_a_common.h"
#include "packet-e212.h"
@ -609,6 +610,7 @@ static expert_field ei_gsm_a_gm_missing_mandatory_element = EI_INIT;
static dissector_handle_t rrc_irat_ho_info_handle;
static dissector_handle_t lte_rrc_ue_eutra_cap_handle;
static dissector_handle_t nbifom_handle;
static dissector_handle_t rlcmac_racap_handle;
static dissector_table_t gprs_sm_pco_subdissector_table; /* GPRS SM PCO PPP Protocols */
@ -1663,6 +1665,16 @@ static const value_string gsm_a_gm_ec_pch_mon_support_vals[] = {
{0, NULL}
};
guint16
de_gmm_ms_radio_acc_cap_rlcmac(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, guint32 offset, guint len, gchar *add_string _U_, int string_len _U_)
{
tvbuff_t *payload_tvb;
payload_tvb = tvb_new_subset_length(tvb, offset, len);
call_dissector(rlcmac_racap_handle, payload_tvb, pinfo, tree);
return len;
}
guint16
de_gmm_ms_radio_acc_cap(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, guint32 offset, guint len, gchar *add_string _U_, int string_len _U_)
{
@ -6372,7 +6384,7 @@ guint16 (*gm_elem_fcn[])(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_
de_gmm_imeisv_req, /* IMEISV Request */
de_gmm_rec_npdu_lst, /* Receive N-PDU Numbers List */
de_gmm_ms_net_cap, /* MS Network Capability */
de_gmm_ms_radio_acc_cap, /* MS Radio Access Capability */
de_gmm_ms_radio_acc_cap_rlcmac, /* MS Radio Access Capability */
de_gmm_cause, /* GMM Cause */
de_gmm_rai, /* Routing Area Identification */
de_gmm_rai2, /* Routing Area Identification 2 */
@ -9681,6 +9693,7 @@ proto_reg_handoff_gsm_a_gm(void)
rrc_irat_ho_info_handle = find_dissector_add_dependency("rrc.irat.irat_ho_info", proto_a_gm);
lte_rrc_ue_eutra_cap_handle = find_dissector_add_dependency("lte-rrc.ue_eutra_cap", proto_a_gm);
nbifom_handle = find_dissector_add_dependency("nbifom", proto_a_gm);
rlcmac_racap_handle = find_dissector_add_dependency("gsm_rlcmac_racap", proto_a_gm);
}
/*

17
epan/dissectors/packet-gsm_rlcmac.c
View File

@ -2819,13 +2819,11 @@ CSN_DESCR_END (MS_RA_capability_value_t)
* This one would be used to decode for instance MS RA Capabilities IE SGSN->MS on the PCU.
* However, an ad-hoc decoder is used in this scenario in wireshark: See packet-gsm_a_gm.c de_gmm_ms_radio_acc_cap().
*/
#if 0
static const
CSN_DESCR_BEGIN (MS_Radio_Access_capability_t)
M_REC_TARRAY_1(MS_Radio_Access_capability_t, MS_RA_capability_value, MS_RA_capability_value_t, Count_MS_RA_capability_value, &hf_ms_ra_capability_value),
M_PADDING_BITS(MS_Radio_Access_capability_t, &hf_padding),
CSN_DESCR_END (MS_Radio_Access_capability_t)
#endif
/* TS44.060 section 12.30 "MS Radio Access Capability 2". Same as above but without spare bits */
static const
@ -9903,6 +9901,20 @@ dissect_gsm_ec_rlcmac_uplink(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree
return dissect_gsm_rlcmac_uplink(tvb, pinfo, tree, &rlc_mac);
}
static int
dissect_gsm_rlcmac_racap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
csnStream_t ar;
MS_Radio_Access_capability_t racap = {0};
int len = tvb_reported_length(tvb);
guint16 bit_length = len * 8;
csnStreamInit(&ar, 0, bit_length, pinfo);
csnStreamDissector(tree, &ar, CSNDESCR(MS_Radio_Access_capability_t), tvb, &racap, ett_gsm_rlcmac);
return len;
}
void
proto_register_gsm_rlcmac(void)
{
@ -18620,6 +18632,7 @@ proto_register_gsm_rlcmac(void)
proto_register_subtree_array(ett, array_length(ett));
expert_gsm_rlcmac = expert_register_protocol(proto_gsm_rlcmac);
expert_register_field_array(expert_gsm_rlcmac, ei, array_length(ei));
register_dissector("gsm_rlcmac_racap", dissect_gsm_rlcmac_racap, proto_gsm_rlcmac);
register_dissector("gsm_rlcmac_ul", dissect_gsm_rlcmac_uplink, proto_gsm_rlcmac);
register_dissector("gsm_rlcmac_dl", dissect_gsm_rlcmac_downlink, proto_gsm_rlcmac);
register_dissector("gsm_ec_rlcmac_ul", dissect_gsm_ec_rlcmac_uplink, proto_gsm_rlcmac);