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 struct osmocom_ms *g_ms;
  39 struct gsm48_sysinfo g_sysinfo = {};
  40
  41 static int try_cbch(struct osmocom_ms *ms, struct gsm48_sysinfo *s)
  42 {
  43         if (!s->si1 || !s->si4)
  44                 return 0;
  45         if (!s->chan_nr) {
  46                 LOGP(DRR, LOGL_INFO, "no CBCH chan_nr found\n");
  47                 return 0;
  48         }
  49
  50         if (s->h) {
  51                 LOGP(DRR, LOGL_INFO, "chan_nr = 0x%02x TSC = %d  MAIO = %d  "
  52                         "HSN = %d  hseq (%d): %s\n",
  53                         s->chan_nr, s->tsc, s->maio, s->hsn,
  54                         s->hopp_len,
  55                         osmo_hexdump((unsigned char *) s->hopping, s->hopp_len * 2));
  56                 return l1ctl_tx_dm_est_req_h1(ms,
  57                         s->maio, s->hsn, s->hopping, s->hopp_len,
  58                         s->chan_nr, s->tsc,
  59                         GSM48_CMODE_SIGN);
  60         } else {
  61                 LOGP(DRR, LOGL_INFO, "chan_nr = 0x%02x TSC = %d  ARFCN = %d\n",
  62                         s->chan_nr, s->tsc, s->arfcn);
  63                 return l1ctl_tx_dm_est_req_h0(ms, s->arfcn,
  64                         s->chan_nr, s->tsc, GSM48_CMODE_SIGN);
  65         }
  66 }
  67
  68
  69 /* receive BCCH at RR layer */
  70 static int bcch(struct osmocom_ms *ms, struct msgb *msg)
  71 {
  72         struct gsm48_system_information_type_header *sih = msgb_l3(msg);
  73         struct gsm48_sysinfo *s = &g_sysinfo;
  74
  75         if (msgb_l3len(msg) != 23) {
  76                 LOGP(DRR, LOGL_NOTICE, "Invalid BCCH message length\n");
  77                 return -EINVAL;
  78         }
  79         switch (sih->system_information) {
  80         case GSM48_MT_RR_SYSINFO_1:
  81                 LOGP(DRR, LOGL_INFO, "New SYSTEM INFORMATION 1\n");
  82                 gsm48_decode_sysinfo1(s,
  83                         (struct gsm48_system_information_type_1 *) sih,
  84                         msgb_l3len(msg));
  85                 return try_cbch(ms, s);
  86         case GSM48_MT_RR_SYSINFO_4:
  87                 LOGP(DRR, LOGL_INFO, "New SYSTEM INFORMATION 4\n");
  88                 gsm48_decode_sysinfo4(s,
  89                         (struct gsm48_system_information_type_4 *) sih,
  90                         msgb_l3len(msg));
  91                 return try_cbch(ms, s);
  92         default:
  93                 return 0;
  94         }
  95 }
  96
  97 static int unit_data_ind(struct osmocom_ms *ms, struct msgb *msg)
  98 {
  99         struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
 100         struct tlv_parsed tv;
 101         uint8_t ch_type, ch_subch, ch_ts;
 102
 103         DEBUGP(DRSL, "RSLms UNIT DATA IND chan_nr=0x%02x link_id=0x%02x\n",
 104                 rllh->chan_nr, rllh->link_id);
 105
 106         rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
 107         if (!TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
 108                 DEBUGP(DRSL, "UNIT_DATA_IND without L3 INFO ?!?\n");
 109                 return -EIO;
 110         }
 111         msg->l3h = (uint8_t *) TLVP_VAL(&tv, RSL_IE_L3_INFO);
 112
 113         rsl_dec_chan_nr(rllh->chan_nr, &ch_type, &ch_subch, &ch_ts);
 114         switch (ch_type) {
 115         case RSL_CHAN_BCCH:
 116                 return bcch(ms, msg);
 117         default:
 118                 return 0;
 119         }
 120 }
 121
 122 static int rcv_rll(struct osmocom_ms *ms, struct msgb *msg)
 123 {
 124         struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
 125         int msg_type = rllh->c.msg_type;
 126
 127         if (msg_type == RSL_MT_UNIT_DATA_IND) {
 128                 unit_data_ind(ms, msg);
 129         } else
 130                 LOGP(DRSL, LOGL_NOTICE, "RSLms message unhandled\n");
 131
 132         msgb_free(msg);
 133
 134         return 0;
 135 }
 136
 137 static int rcv_rsl(struct msgb *msg, struct osmocom_ms *ms)
 138 {
 139         struct abis_rsl_common_hdr *rslh = msgb_l2(msg);
 140         int rc = 0;
 141
 142         switch (rslh->msg_discr & 0xfe) {
 143         case ABIS_RSL_MDISC_RLL:
 144                 rc = rcv_rll(ms, msg);
 145                 break;
 146         default:
 147                 LOGP(DRSL, LOGL_NOTICE, "unknown RSLms msg_discr 0x%02x\n",
 148                         rslh->msg_discr);
 149                 msgb_free(msg);
 150                 rc = -EINVAL;
 151                 break;
 152         }
 153
 154         return rc;
 155 }
 156
 157 static int signal_cb(unsigned int subsys, unsigned int signal,
 158                      void *handler_data, void *signal_data)
 159 {
 160         struct osmocom_ms *ms;
 161
 162         if (subsys != SS_L1CTL)
 163                 return 0;
 164
 165         switch (signal) {
 166         case S_L1CTL_RESET:
 167         case S_L1CTL_FBSB_ERR:
 168                 ms = g_ms;
 169                 return l1ctl_tx_fbsb_req(ms, ms->test_arfcn,
 170                         L1CTL_FBSB_F_FB01SB, 100, 0, CCCH_MODE_COMBINED);
 171         case S_L1CTL_FBSB_RESP:
 172                 return 0;
 173         }
 174         return 0;
 175 }
 176
 177 int l23_app_init(struct osmocom_ms *ms)
 178 {
 179         /* don't do layer3_init() as we don't want an actualy L3 */
 180
 181         g_ms = ms;
 182         osmol2_register_handler(ms, &rcv_rsl);
 183
 184         l1ctl_tx_reset_req(ms, L1CTL_RES_T_FULL);
 185         /* FIXME: L1CTL_RES_T_FULL doesn't reset dedicated mode
 186          * (if previously set), so we release it here. */
 187         l1ctl_tx_dm_rel_req(ms);
 188         return osmo_signal_register_handler(SS_L1CTL, &signal_cb, NULL);
 189 }
 190
 191 static struct l23_app_info info = {
 192         .copyright      = "Copyright (C) 2010 Harald Welte <laforge@gnumonks.org>\n",
 193         .contribution   = "Contributions by Holger Hans Peter Freyther\n",
 194 };
 195
 196 struct l23_app_info *l23_app_info()
 197 {
 198         return &info;
 199 }