src/host/layer23/src/misc/app_cbch_sniff.c

   1 /* CBCH passive sniffer */
   2
   3 /* (C) 2010 by Holger Hans Peter Freyther
   4  * (C) 2010 by Harald Welte <laforge@gnumonks.org>
   5  * (C) 2010 by Alex Badea <vamposdecampos@gmail.com>
   6  *
   7  * All Rights Reserved
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write to the Free Software Foundation, Inc.,
  21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  22  *
  23  */
  24
  25 #include <osmocom/bb/common/osmocom_data.h>
  26 #include <osmocom/bb/common/l1ctl.h>
  27 #include <osmocom/bb/common/lapdm.h>
  28 #include <osmocom/bb/common/logging.h>
  29 #include <osmocom/bb/common/l23_app.h>
  30 #include <osmocom/bb/misc/layer3.h>
  31
  32 #include <osmocom/core/msgb.h>
  33 #include <osmocom/core/talloc.h>
  34 #include <osmocom/core/select.h>
  35 #include <osmocom/core/signal.h>
  36 #include <osmocom/gsm/rsl.h>
  37
  38 #include <l1ctl_proto.h>
  39
  40 struct osmocom_ms *g_ms;
  41 struct gsm48_sysinfo g_sysinfo = {};
  42
  43 static int try_cbch(struct osmocom_ms *ms, struct gsm48_sysinfo *s)
  44 {
  45         if (!s->si1 || !s->si4)
  46                 return 0;
  47         if (!s->chan_nr) {
  48                 LOGP(DRR, LOGL_INFO, "no CBCH chan_nr found\n");
  49                 return 0;
  50         }
  51
  52         if (s->h) {
  53                 LOGP(DRR, LOGL_INFO, "chan_nr = 0x%02x TSC = %d  MAIO = %d  "
  54                         "HSN = %d  hseq (%d): %s\n",
  55                         s->chan_nr, s->tsc, s->maio, s->hsn,
  56                         s->hopp_len,
  57                         osmo_hexdump((unsigned char *) s->hopping, s->hopp_len * 2));
  58                 return l1ctl_tx_dm_est_req_h1(ms,
  59                         s->maio, s->hsn, s->hopping, s->hopp_len,
  60                         s->chan_nr, s->tsc,
  61                         GSM48_CMODE_SIGN);
  62         } else {
  63                 LOGP(DRR, LOGL_INFO, "chan_nr = 0x%02x TSC = %d  ARFCN = %d\n",
  64                         s->chan_nr, s->tsc, s->arfcn);
  65                 return l1ctl_tx_dm_est_req_h0(ms, s->arfcn,
  66                         s->chan_nr, s->tsc, GSM48_CMODE_SIGN);
  67         }
  68 }
  69
  70
  71 /* receive BCCH at RR layer */
  72 static int bcch(struct osmocom_ms *ms, struct msgb *msg)
  73 {
  74         struct gsm48_system_information_type_header *sih = msgb_l3(msg);
  75         struct gsm48_sysinfo *s = &g_sysinfo;
  76
  77         if (msgb_l3len(msg) != 23) {
  78                 LOGP(DRR, LOGL_NOTICE, "Invalid BCCH message length\n");
  79                 return -EINVAL;
  80         }
  81         switch (sih->system_information) {
  82         case GSM48_MT_RR_SYSINFO_1:
  83                 LOGP(DRR, LOGL_INFO, "New SYSTEM INFORMATION 1\n");
  84                 gsm48_decode_sysinfo1(s,
  85                         (struct gsm48_system_information_type_1 *) sih,
  86                         msgb_l3len(msg));
  87                 return try_cbch(ms, s);
  88         case GSM48_MT_RR_SYSINFO_4:
  89                 LOGP(DRR, LOGL_INFO, "New SYSTEM INFORMATION 4\n");
  90                 gsm48_decode_sysinfo4(s,
  91                         (struct gsm48_system_information_type_4 *) sih,
  92                         msgb_l3len(msg));
  93                 return try_cbch(ms, s);
  94         default:
  95                 return 0;
  96         }
  97 }
  98
  99 static int unit_data_ind(struct osmocom_ms *ms, struct msgb *msg)
 100 {
 101         struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
 102         struct tlv_parsed tv;
 103         uint8_t ch_type, ch_subch, ch_ts;
 104
 105         DEBUGP(DRSL, "RSLms UNIT DATA IND chan_nr=0x%02x link_id=0x%02x\n",
 106                 rllh->chan_nr, rllh->link_id);
 107
 108         rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
 109         if (!TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
 110                 DEBUGP(DRSL, "UNIT_DATA_IND without L3 INFO ?!?\n");
 111                 return -EIO;
 112         }
 113         msg->l3h = (uint8_t *) TLVP_VAL(&tv, RSL_IE_L3_INFO);
 114
 115         rsl_dec_chan_nr(rllh->chan_nr, &ch_type, &ch_subch, &ch_ts);
 116         switch (ch_type) {
 117         case RSL_CHAN_BCCH:
 118                 return bcch(ms, msg);
 119         default:
 120                 return 0;
 121         }
 122 }
 123
 124 static int rcv_rll(struct osmocom_ms *ms, struct msgb *msg)
 125 {
 126         struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
 127         int msg_type = rllh->c.msg_type;
 128
 129         if (msg_type == RSL_MT_UNIT_DATA_IND) {
 130                 unit_data_ind(ms, msg);
 131         } else
 132                 LOGP(DRSL, LOGL_NOTICE, "RSLms message unhandled\n");
 133
 134         msgb_free(msg);
 135
 136         return 0;
 137 }
 138
 139 static int rcv_rsl(struct msgb *msg, struct lapdm_entity *le, void *l3ctx)
 140 {
 141         struct osmocom_ms *ms = l3ctx;
 142         struct abis_rsl_common_hdr *rslh = msgb_l2(msg);
 143         int rc = 0;
 144
 145         switch (rslh->msg_discr & 0xfe) {
 146         case ABIS_RSL_MDISC_RLL:
 147                 rc = rcv_rll(ms, msg);
 148                 break;
 149         default:
 150                 LOGP(DRSL, LOGL_NOTICE, "unknown RSLms msg_discr 0x%02x\n",
 151                         rslh->msg_discr);
 152                 msgb_free(msg);
 153                 rc = -EINVAL;
 154                 break;
 155         }
 156
 157         return rc;
 158 }
 159
 160 static int signal_cb(unsigned int subsys, unsigned int signal,
 161                      void *handler_data, void *signal_data)
 162 {
 163         struct osmocom_ms *ms;
 164
 165         if (subsys != SS_L1CTL)
 166                 return 0;
 167
 168         switch (signal) {
 169         case S_L1CTL_RESET:
 170         case S_L1CTL_FBSB_ERR:
 171                 ms = g_ms;
 172                 return l1ctl_tx_fbsb_req(ms, ms->test_arfcn,
 173                         L1CTL_FBSB_F_FB01SB, 100, 0, CCCH_MODE_COMBINED);
 174         case S_L1CTL_FBSB_RESP:
 175                 return 0;
 176         }
 177         return 0;
 178 }
 179
 180 int l23_app_init(struct osmocom_ms *ms)
 181 {
 182         /* don't do layer3_init() as we don't want an actualy L3 */
 183
 184         g_ms = ms;
 185         lapdm_channel_set_l1(&ms->lapdm_channel, &rcv_rsl, ms);
 186
 187         l1ctl_tx_reset_req(ms, L1CTL_RES_T_FULL);
 188         /* FIXME: L1CTL_RES_T_FULL doesn't reset dedicated mode
 189          * (if previously set), so we release it here. */
 190         l1ctl_tx_dm_rel_req(ms);
 191         return osmo_signal_register_handler(SS_L1CTL, &signal_cb, NULL);
 192 }
 193
 194 static struct l23_app_info info = {
 195         .copyright      = "Copyright (C) 2010 Harald Welte <laforge@gnumonks.org>\n",
 196         .contribution   = "Contributions by Holger Hans Peter Freyther\n",
 197 };
 198
 199 struct l23_app_info *l23_app_info()
 200 {
 201         return &info;
 202 }