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/misc/layer3.h>
  30
  31 #include <osmocore/msgb.h>
  32 #include <osmocore/talloc.h>
  33 #include <osmocore/select.h>
  34 #include <osmocore/signal.h>
  35 #include <osmocore/rsl.h>
  36
  37 struct osmocom_ms *g_ms;
  38 struct gsm48_sysinfo g_sysinfo = {};
  39
  40 static int try_cbch(struct osmocom_ms *ms, struct gsm48_sysinfo *s)
  41 {
  42         if (!s->si1 || !s->si4)
  43                 return 0;
  44         if (!s->chan_nr) {
  45                 LOGP(DRR, LOGL_INFO, "no CBCH chan_nr found\n");
  46                 return 0;
  47         }
  48
  49         if (s->h) {
  50                 LOGP(DRR, LOGL_INFO, "chan_nr = 0x%02x TSC = %d  MAIO = %d  "
  51                         "HSN = %d  hseq (%d): %s\n",
  52                         s->chan_nr, s->tsc, s->maio, s->hsn,
  53                         s->hopp_len,
  54                         hexdump((unsigned char *) s->hopping, s->hopp_len * 2));
  55                 return l1ctl_tx_dm_est_req_h1(ms,
  56                         s->maio, s->hsn, s->hopping, s->hopp_len,
  57                         s->chan_nr, s->tsc,
  58                         GSM48_CMODE_SIGN);
  59         } else {
  60                 LOGP(DRR, LOGL_INFO, "chan_nr = 0x%02x TSC = %d  ARFCN = %d\n",
  61                         s->chan_nr, s->tsc, s->arfcn);
  62                 return l1ctl_tx_dm_est_req_h0(ms, s->arfcn,
  63                         s->chan_nr, s->tsc, GSM48_CMODE_SIGN);
  64         }
  65 }
  66
  67
  68 /* receive BCCH at RR layer */
  69 static int bcch(struct osmocom_ms *ms, struct msgb *msg)
  70 {
  71         struct gsm48_system_information_type_header *sih = msgb_l3(msg);
  72         struct gsm48_sysinfo *s = &g_sysinfo;
  73
  74         if (msgb_l3len(msg) != 23) {
  75                 LOGP(DRR, LOGL_NOTICE, "Invalid BCCH message length\n");
  76                 return -EINVAL;
  77         }
  78         switch (sih->system_information) {
  79         case GSM48_MT_RR_SYSINFO_1:
  80                 LOGP(DRR, LOGL_INFO, "New SYSTEM INFORMATION 1\n");
  81                 gsm48_decode_sysinfo1(s,
  82                         (struct gsm48_system_information_type_1 *) sih,
  83                         msgb_l3len(msg));
  84                 return try_cbch(ms, s);
  85         case GSM48_MT_RR_SYSINFO_4:
  86                 LOGP(DRR, LOGL_INFO, "New SYSTEM INFORMATION 4\n");
  87                 gsm48_decode_sysinfo4(s,
  88                         (struct gsm48_system_information_type_4 *) sih,
  89                         msgb_l3len(msg));
  90                 return try_cbch(ms, s);
  91         default:
  92                 return 0;
  93         }
  94 }
  95
  96 static int unit_data_ind(struct osmocom_ms *ms, struct msgb *msg)
  97 {
  98         struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
  99         struct tlv_parsed tv;
 100         uint8_t ch_type, ch_subch, ch_ts;
 101
 102         DEBUGP(DRSL, "RSLms UNIT DATA IND chan_nr=0x%02x link_id=0x%02x\n",
 103                 rllh->chan_nr, rllh->link_id);
 104
 105         rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
 106         if (!TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
 107                 DEBUGP(DRSL, "UNIT_DATA_IND without L3 INFO ?!?\n");
 108                 return -EIO;
 109         }
 110         msg->l3h = (uint8_t *) TLVP_VAL(&tv, RSL_IE_L3_INFO);
 111
 112         rsl_dec_chan_nr(rllh->chan_nr, &ch_type, &ch_subch, &ch_ts);
 113         switch (ch_type) {
 114         case RSL_CHAN_BCCH:
 115                 return bcch(ms, msg);
 116         default:
 117                 return 0;
 118         }
 119 }
 120
 121 static int rcv_rll(struct osmocom_ms *ms, struct msgb *msg)
 122 {
 123         struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
 124         int msg_type = rllh->c.msg_type;
 125
 126         if (msg_type == RSL_MT_UNIT_DATA_IND) {
 127                 unit_data_ind(ms, msg);
 128         } else
 129                 LOGP(DRSL, LOGL_NOTICE, "RSLms message unhandled\n");
 130
 131         msgb_free(msg);
 132
 133         return 0;
 134 }
 135
 136 static int rcv_rsl(struct msgb *msg, struct osmocom_ms *ms)
 137 {
 138         struct abis_rsl_common_hdr *rslh = msgb_l2(msg);
 139         int rc = 0;
 140
 141         switch (rslh->msg_discr & 0xfe) {
 142         case ABIS_RSL_MDISC_RLL:
 143                 rc = rcv_rll(ms, msg);
 144                 break;
 145         default:
 146                 LOGP(DRSL, LOGL_NOTICE, "unknown RSLms msg_discr 0x%02x\n",
 147                         rslh->msg_discr);
 148                 msgb_free(msg);
 149                 rc = -EINVAL;
 150                 break;
 151         }
 152
 153         return rc;
 154 }
 155
 156 static int signal_cb(unsigned int subsys, unsigned int signal,
 157                      void *handler_data, void *signal_data)
 158 {
 159         struct osmocom_ms *ms;
 160
 161         if (subsys != SS_L1CTL)
 162                 return 0;
 163
 164         switch (signal) {
 165         case S_L1CTL_RESET:
 166         case S_L1CTL_FBSB_ERR:
 167                 ms = g_ms;
 168                 return l1ctl_tx_fbsb_req(ms, ms->test_arfcn,
 169                         L1CTL_FBSB_F_FB01SB, 100, 0, CCCH_MODE_COMBINED);
 170         case S_L1CTL_FBSB_RESP:
 171                 return 0;
 172         }
 173         return 0;
 174 }
 175
 176 int l23_app_init(struct osmocom_ms *ms)
 177 {
 178         /* don't do layer3_init() as we don't want an actualy L3 */
 179
 180         g_ms = ms;
 181         osmol2_register_handler(ms, &rcv_rsl);
 182
 183         l1ctl_tx_reset_req(ms, L1CTL_RES_T_FULL);
 184         /* FIXME: L1CTL_RES_T_FULL doesn't reset dedicated mode
 185          * (if previously set), so we release it here. */
 186         l1ctl_tx_dm_rel_req(ms);
 187         return register_signal_handler(SS_L1CTL, &signal_cb, NULL);
 188 }