forked from osmocom/wireshark
![Guy Harris](/assets/img/avatar_default.png)
This emphasizes that there is no such thing as *the* routine to construct a subset tvbuff; you need to choose one of tvb_new_subset_remaining() (if you want a new tvbuff that contains everything past a certain point in an existing tvbuff), tvb_new_subset_length() (if you want a subset that contains everything past a certain point, for some number of bytes, in an existing tvbuff), and tvb_new_subset_length_caplen() (for all other cases). Many of the calls to tvb_new_subset_length_caplen() should really be calling one of the other routines; that's the next step. (This also makes it easier to find the calls that need fixing.) Change-Id: Ieb3d676d8cda535451c119487d7cd3b559221f2b Reviewed-on: https://code.wireshark.org/review/19597 Reviewed-by: Guy Harris <guy@alum.mit.edu>
319 lines
9.3 KiB
C
319 lines
9.3 KiB
C
/* packet-gsm_um.c
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* Routines for GSM Um packet disassembly
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* Duncan Salerno <duncan.salerno@googlemail.com>
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "config.h"
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#include <epan/packet.h>
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#include <epan/prefs.h>
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#include <wiretap/wtap.h>
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void proto_register_gsm_um(void);
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void proto_reg_handoff_gsm_um(void);
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static int proto_gsm_um = -1;
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static int hf_gsm_um_direction = -1;
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static int hf_gsm_um_channel = -1;
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static int hf_gsm_um_bsic = -1;
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static int hf_gsm_um_arfcn = -1;
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static int hf_gsm_um_band = -1;
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static int hf_gsm_um_frequency = -1;
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static int hf_gsm_um_frame = -1;
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static int hf_gsm_um_error = -1;
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static int hf_gsm_um_timeshift = -1;
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static int hf_gsm_um_l2_pseudo_len = -1;
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static gint ett_gsm_um = -1;
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static dissector_handle_t lapdm_handle;
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static dissector_handle_t dtap_handle;
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static gboolean dcs1800_gsm = TRUE;
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#define GSM_UM_L2_PSEUDO_LEN 0xfc
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static void
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decode_arfcn(guint16 arfcn, const char **band, guint *uplink, guint *downlink)
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{
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/* Decode ARFCN to frequency using GSM 05.05 */
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if( arfcn >= 1 && arfcn <= 124 ) {
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*band = "P-GSM 900";
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*uplink = 890000 + 200 * arfcn;
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*downlink = *uplink + 45000;
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}
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else if( arfcn == 0 ) {
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*band = "E-GSM 900";
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*uplink = 890000 + 200 * arfcn;
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*downlink = *uplink + 45000;
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}
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else if( arfcn >= 975 && arfcn <= 1023 ) {
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*band = "E-GSM 900";
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*uplink = 890000 + 200 * (arfcn - 1024);
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*downlink = *uplink + 45000;
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}
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else if( arfcn >= 955 && arfcn <= 974 ) {
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*band = "R-GSM 900";
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*uplink = 890000 + 200 * (arfcn - 1024);
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*downlink = *uplink + 45000;
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}
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else if( arfcn >= 512 && arfcn <= 885 && dcs1800_gsm) {
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*band = "DCS 1800";
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*uplink = 1710200 + 200 * (arfcn - 512);
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*downlink = *uplink + 95000;
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}
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else if( arfcn >= 512 && arfcn <= 810 && !dcs1800_gsm) {
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*band = "PCS 1900";
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*uplink = 1850200 + 200 * (arfcn - 512);
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*downlink = *uplink + 80000;
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}
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else if( arfcn >= 259 && arfcn <= 293 ) {
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*band = "GSM 450";
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*uplink = 450600 + 200 * (arfcn - 259);
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*downlink = *uplink + 10000;
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}
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else if( arfcn >= 306 && arfcn <= 340 ) {
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*band = "GSM 480";
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*uplink = 479000 + 200 * (arfcn - 306);
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*downlink = *uplink + 10000;
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}
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else if( arfcn >= 128 && arfcn <= 251 ) {
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*band = "GSM 850";
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*uplink = 824200 + 200 * (arfcn - 128);
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*downlink = *uplink + 45000;
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}
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else {
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*band = "Unknown";
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*uplink = *downlink = 0;
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}
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}
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static int
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dissect_gsm_um(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
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{
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proto_tree *gsm_um_tree = NULL;
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proto_item *ti;
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "GSM Um");
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if (pinfo->pseudo_header->gsm_um.uplink) {
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col_set_str(pinfo->cinfo, COL_RES_DL_DST, "BTS");
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col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "MS");
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}
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else {
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switch (pinfo->pseudo_header->gsm_um.channel) {
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case GSM_UM_CHANNEL_BCCH:
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case GSM_UM_CHANNEL_CCCH:
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case GSM_UM_CHANNEL_PCH:
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case GSM_UM_CHANNEL_AGCH:
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col_set_str(pinfo->cinfo, COL_RES_DL_DST, "Broadcast");
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break;
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default:
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col_set_str(pinfo->cinfo, COL_RES_DL_DST, "MS");
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break;
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}
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col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "BTS");
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}
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if (tree) {
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const char *channel;
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ti = proto_tree_add_item(tree, proto_gsm_um, tvb, 0, 0, ENC_NA);
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gsm_um_tree = proto_item_add_subtree(ti, ett_gsm_um);
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switch( pinfo->pseudo_header->gsm_um.channel ) {
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case GSM_UM_CHANNEL_BCCH: channel = "BCCH"; break;
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case GSM_UM_CHANNEL_CCCH: channel = "CCCH"; break;
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case GSM_UM_CHANNEL_PCH: channel = "PCH"; break;
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case GSM_UM_CHANNEL_AGCH: channel = "AGCH"; break;
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case GSM_UM_CHANNEL_SACCH: channel = "SACCH"; break;
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case GSM_UM_CHANNEL_FACCH: channel = "FACCH"; break;
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case GSM_UM_CHANNEL_SDCCH: channel = "SDCCH"; break;
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default: channel = "Unknown"; break;
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}
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if( pinfo->pseudo_header->gsm_um.uplink ) {
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proto_tree_add_string(gsm_um_tree, hf_gsm_um_direction, tvb, 0, 0, "Uplink");
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}
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else {
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proto_tree_add_string(gsm_um_tree, hf_gsm_um_direction, tvb, 0, 0, "Downlink");
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}
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proto_tree_add_string(gsm_um_tree, hf_gsm_um_channel, tvb, 0, 0, channel);
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/* Show the other fields, if we have them (ie. downlink, BTS->MS) */
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if( !pinfo->pseudo_header->gsm_um.uplink ) {
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const char *band;
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guint downlink, uplink;
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decode_arfcn(pinfo->pseudo_header->gsm_um.arfcn, &band, &uplink, &downlink);
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proto_tree_add_uint(gsm_um_tree, hf_gsm_um_arfcn, tvb, 0, 0,
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pinfo->pseudo_header->gsm_um.arfcn);
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proto_tree_add_string(gsm_um_tree, hf_gsm_um_band, tvb, 0, 0,
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band);
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proto_tree_add_uint_format_value(gsm_um_tree, hf_gsm_um_frequency, tvb, 0, 0,
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downlink, "%u.%03uMHz", downlink / 1000, downlink % 1000);
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proto_tree_add_uint(gsm_um_tree, hf_gsm_um_bsic, tvb, 0, 0,
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pinfo->pseudo_header->gsm_um.bsic);
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proto_tree_add_uint(gsm_um_tree, hf_gsm_um_frame, tvb, 0, 0,
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pinfo->pseudo_header->gsm_um.tdma_frame);
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proto_tree_add_uint(gsm_um_tree, hf_gsm_um_error, tvb, 0, 0,
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pinfo->pseudo_header->gsm_um.error);
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proto_tree_add_uint(gsm_um_tree, hf_gsm_um_timeshift, tvb, 0, 0,
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pinfo->pseudo_header->gsm_um.timeshift);
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}
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}
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/* TODO: If CCCH downlink could work out of PCH or AGCH by peeking at next bytes, uplink is RACH */
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switch( pinfo->pseudo_header->gsm_um.channel ) {
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case GSM_UM_CHANNEL_BCCH:
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case GSM_UM_CHANNEL_CCCH:
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case GSM_UM_CHANNEL_PCH:
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case GSM_UM_CHANNEL_AGCH:
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if( !pinfo->pseudo_header->gsm_um.uplink ) {
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tvbuff_t *next_tvb;
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guint8 pseudo_len, len_left, len_byte;
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len_left = tvb_reported_length(tvb);
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len_byte = tvb_get_guint8(tvb, 0);
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pseudo_len = len_byte >> 2;
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next_tvb = tvb_new_subset_length_caplen(tvb, 1, MIN(len_left, pseudo_len), -1);
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if (tree) {
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proto_tree_add_uint(gsm_um_tree, hf_gsm_um_l2_pseudo_len, tvb, 0, 1,
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len_byte);
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}
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/* Only dissect non-empty frames */
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if( tvb_reported_length(next_tvb) ) {
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call_dissector(dtap_handle, next_tvb, pinfo, tree);
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}
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}
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else {
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/* Either RACH, or something invalid */
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call_data_dissector(tvb, pinfo, tree);
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}
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break;
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case GSM_UM_CHANNEL_SACCH:
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case GSM_UM_CHANNEL_FACCH:
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case GSM_UM_CHANNEL_SDCCH:
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call_dissector(lapdm_handle, tvb, pinfo, tree);
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break;
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default:
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call_data_dissector(tvb, pinfo, tree);
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break;
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}
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return tvb_captured_length(tvb);
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}
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void
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proto_register_gsm_um(void)
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{
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static hf_register_info hf[] = {
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{ &hf_gsm_um_direction,
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{ "Direction", "gsm_um.direction", FT_STRINGZ, BASE_NONE,
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NULL, 0x0, NULL, HFILL }},
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{ &hf_gsm_um_channel,
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{ "Channel", "gsm_um.channel", FT_STRINGZ, BASE_NONE,
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NULL, 0x0, NULL, HFILL }},
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{ &hf_gsm_um_bsic,
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{ "BSIC", "gsm_um.bsic", FT_UINT8, BASE_DEC,
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NULL, 0x0, "Base station identity code", HFILL }},
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{ &hf_gsm_um_arfcn,
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{ "ARFCN", "gsm_um.arfcn", FT_UINT16, BASE_DEC,
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NULL, 0x0, "Absolute radio frequency channel number", HFILL }},
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{ &hf_gsm_um_band,
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{ "Band", "gsm_um.band", FT_STRING, BASE_NONE,
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NULL, 0x0, NULL, HFILL }},
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{ &hf_gsm_um_frequency,
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{ "Frequency", "gsm_um.frequency", FT_UINT32, BASE_DEC,
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NULL, 0x0, NULL, HFILL }},
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{ &hf_gsm_um_frame,
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{ "TDMA Frame", "gsm_um.frame", FT_UINT32, BASE_DEC,
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NULL, 0x0, NULL, HFILL }},
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{ &hf_gsm_um_error,
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{ "Error", "gsm_um.error", FT_UINT8, BASE_DEC,
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NULL, 0x0, NULL, HFILL }},
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{ &hf_gsm_um_timeshift,
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{ "Timeshift", "gsm_um.timeshift", FT_UINT16, BASE_DEC,
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NULL, 0x0, NULL, HFILL }},
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{ &hf_gsm_um_l2_pseudo_len,
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{ "L2 Pseudo Length", "gsm_um.l2_pseudo_len", FT_UINT8, BASE_DEC,
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NULL, GSM_UM_L2_PSEUDO_LEN, NULL, HFILL }}
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};
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static gint *ett[] = {
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&ett_gsm_um
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};
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module_t *gsm_um_module;
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proto_gsm_um = proto_register_protocol("GSM Um Interface", "GSM Um", "gsm_um");
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proto_register_field_array(proto_gsm_um, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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gsm_um_module = prefs_register_protocol(proto_gsm_um, NULL);
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prefs_register_bool_preference(gsm_um_module, "dcs1800",
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"Treat ARFCN 512-810 as DCS 1800 rather than PCS 1900",
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"Treat ARFCN 512-810 as DCS 1800 rather than PCS 1900",
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&dcs1800_gsm);
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}
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void
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proto_reg_handoff_gsm_um(void)
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{
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dissector_handle_t gsm_um_handle;
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lapdm_handle = find_dissector_add_dependency("lapdm", proto_gsm_um);
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dtap_handle = find_dissector_add_dependency("gsm_a_dtap", proto_gsm_um);
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gsm_um_handle = create_dissector_handle(dissect_gsm_um, proto_gsm_um);
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dissector_add_uint("wtap_encap", WTAP_ENCAP_GSM_UM, gsm_um_handle);
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}
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/*
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* Editor modelines - http://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 8
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* tab-width: 8
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* indent-tabs-mode: t
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* End:
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*
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* vi: set shiftwidth=8 tabstop=8 noexpandtab:
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* :indentSize=8:tabSize=8:noTabs=false:
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*/
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