diff options
Diffstat (limited to 'src/common')
| -rw-r--r-- | src/common/l1sap.c | 181 |
1 files changed, 179 insertions, 2 deletions
diff --git a/src/common/l1sap.c b/src/common/l1sap.c index 9068bb88..14dbde9b 100644 --- a/src/common/l1sap.c +++ b/src/common/l1sap.c @@ -69,6 +69,54 @@ struct msgb *l1sap_msgb_alloc(unsigned int l2_len) return msg; } +static int l1sap_tx_ciph_req(struct gsm_bts_trx *trx, uint8_t chan_nr, + uint8_t downlink, uint8_t uplink) +{ + struct osmo_phsap_prim l1sap_ciph; + + osmo_prim_init(&l1sap_ciph.oph, SAP_GSM_PH, PRIM_MPH_INFO, + PRIM_OP_REQUEST, NULL); + l1sap_ciph.u.info.type = PRIM_INFO_ACT_CIPH; + l1sap_ciph.u.info.u.ciph_req.chan_nr = chan_nr; + l1sap_ciph.u.info.u.ciph_req.downlink = downlink; + l1sap_ciph.u.info.u.ciph_req.uplink = uplink; + + return l1sap_down(trx, &l1sap_ciph); +} + + +/* check if the message is a GSM48_MT_RR_CIPH_M_CMD, and if yes, enable + * uni-directional de-cryption on the uplink. We need this ugly layering + * violation as we have no way of passing down L3 metadata (RSL CIPHERING CMD) + * to this point in L1 */ +static int check_for_ciph_cmd(struct msgb *msg, struct gsm_lchan *lchan, + uint8_t chan_nr) +{ + + /* only do this if we are in the right state */ + switch (lchan->ciph_state) { + case LCHAN_CIPH_NONE: + case LCHAN_CIPH_RX_REQ: + break; + default: + return 0; + } + + /* First byte (Address Field) of LAPDm header) */ + if (msg->data[0] != 0x03) + return 0; + /* First byte (protocol discriminator) of RR */ + if ((msg->data[3] & 0xF) != GSM48_PDISC_RR) + return 0; + /* 2nd byte (msg type) of RR */ + if ((msg->data[4] & 0x3F) != GSM48_MT_RR_CIPH_M_CMD) + return 0; + + l1sap_tx_ciph_req(lchan->ts->trx, chan_nr, 0, 1); + + return 1; +} + /* time information received from bts model */ static int l1sap_info_time_ind(struct gsm_bts_trx *trx, struct osmo_phsap_prim *l1sap, @@ -193,10 +241,13 @@ static int l1sap_ph_rts_ind(struct gsm_bts_trx *trx, { struct msgb *msg = l1sap->oph.msg; struct gsm_time g_time; + struct gsm_lchan *lchan; uint8_t chan_nr, link_id; - uint8_t tn; + uint8_t tn, ss; uint32_t fn; uint8_t *p, *si; + struct lapdm_entity *le; + struct osmo_phsap_prim pp; int rc; chan_nr = rts_ind->chan_nr; @@ -241,6 +292,52 @@ static int l1sap_ph_rts_ind(struct gsm_bts_trx *trx, memcpy(p, si, GSM_MACBLOCK_LEN); else memcpy(p, fill_frame, GSM_MACBLOCK_LEN); + } else if (!(chan_nr & 0x80)) { /* only TCH/F, TCH/H, SDCCH/4 and SDCCH/8 have C5 bit cleared */ + if (L1SAP_IS_CHAN_TCHH(chan_nr)) + ss = L1SAP_CHAN2SS_TCHH(chan_nr); /* TCH/H */ + else if (L1SAP_IS_CHAN_SDCCH4(chan_nr)) + ss = L1SAP_CHAN2SS_SDCCH4(chan_nr); /* SDCCH/4 */ + else if (L1SAP_IS_CHAN_SDCCH8(chan_nr)) + ss = L1SAP_CHAN2SS_SDCCH8(chan_nr); /* SDCCH/8 */ + else + ss = 0; /* TCH/F */ + lchan = &trx->ts[tn].lchan[ss]; + if (L1SAP_IS_LINK_SACCH(link_id)) { + p = msgb_put(msg, GSM_MACBLOCK_LEN); + /* L1-header, if not set/modified by layer 1 */ + p[0] = lchan->ms_power; + p[1] = lchan->rqd_ta; + le = &lchan->lapdm_ch.lapdm_acch; + } else + le = &lchan->lapdm_ch.lapdm_dcch; + rc = lapdm_phsap_dequeue_prim(le, &pp); + if (rc < 0) { + if (L1SAP_IS_LINK_SACCH(link_id)) { + /* No SACCH data from LAPDM pending, send SACCH filling */ + uint8_t *si = lchan_sacch_get(lchan); + if (si) { + /* The +2 is empty space where the DSP inserts the L1 hdr */ + memcpy(p + 2, si, GSM_MACBLOCK_LEN - 2); + } else + memcpy(p + 2, fill_frame, GSM_MACBLOCK_LEN - 2); + } else if ((!L1SAP_IS_CHAN_TCHF(chan_nr) && !L1SAP_IS_CHAN_TCHH(chan_nr)) + || lchan->rsl_cmode == RSL_CMOD_SPD_SIGN) { + /* send fill frame only, if not TCH/x != Signalling, otherwise send empty frame */ + p = msgb_put(msg, GSM_MACBLOCK_LEN); + memcpy(p, fill_frame, GSM_MACBLOCK_LEN); + } /* else the message remains empty, so TCH frames are sent */ + } else { + /* The +2 is empty space where the DSP inserts the L1 hdr */ + if (L1SAP_IS_LINK_SACCH(link_id)) + memcpy(p + 2, pp.oph.msg->data + 2, GSM_MACBLOCK_LEN - 2); + else { + p = msgb_put(msg, GSM_MACBLOCK_LEN); + memcpy(p, pp.oph.msg->data, GSM_MACBLOCK_LEN); + /* check if it is a RR CIPH MODE CMD. if yes, enable RX ciphering */ + check_for_ciph_cmd(pp.oph.msg, lchan, chan_nr); + } + msgb_free(pp.oph.msg); + } } else if (L1SAP_IS_CHAN_AGCH_PCH(chan_nr)) { p = msgb_put(msg, GSM_MACBLOCK_LEN); #warning "TODO: Yet another assumption that BS_AG_BLKS_RES=1" @@ -352,12 +449,46 @@ static int l1sap_tch_rts_ind(struct gsm_bts_trx *trx, return 0; } +/* process radio link timeout counter S */ +static void radio_link_timeout(struct gsm_lchan *lchan, int bad_frame) +{ + struct gsm_bts_role_bts *btsb = lchan->ts->trx->bts->role; + + /* if link loss criterion already reached */ + if (lchan->s == 0) { + DEBUGP(DMEAS, "%s radio link counter S already 0.\n", + gsm_lchan_name(lchan)); + return; + } + + if (bad_frame) { + /* count down radio link counter S */ + lchan->s--; + DEBUGP(DMEAS, "%s counting down radio link counter S=%d\n", + gsm_lchan_name(lchan), lchan->s); + if (lchan->s == 0) + rsl_tx_conn_fail(lchan, RSL_ERR_RADIO_LINK_FAIL); + return; + } + + if (lchan->s < btsb->radio_link_timeout) { + /* count up radio link counter S */ + lchan->s += 2; + if (lchan->s > btsb->radio_link_timeout) + lchan->s = btsb->radio_link_timeout; + DEBUGP(DMEAS, "%s counting up radio link counter S=%d\n", + gsm_lchan_name(lchan), lchan->s); + } +} + /* DATA received from bts model */ static int l1sap_ph_data_ind(struct gsm_bts_trx *trx, struct osmo_phsap_prim *l1sap, struct ph_data_param *data_ind) { struct msgb *msg = l1sap->oph.msg; struct gsm_time g_time; + struct gsm_lchan *lchan; + struct lapdm_entity *le; uint8_t *data = msg->l2h; int len = msgb_l2len(msg); uint8_t chan_nr, link_id; @@ -397,7 +528,53 @@ static int l1sap_ph_data_ind(struct gsm_bts_trx *trx, return 0; } - return 0; + lchan = &trx->ts[tn].lchan[ss]; + + /* bad frame */ + if (len == 0) { + if (L1SAP_IS_LINK_SACCH(link_id)) + radio_link_timeout(lchan, 1); + return -EINVAL; + } + + if (L1SAP_IS_LINK_SACCH(link_id)) { + radio_link_timeout(lchan, 0); + le = &lchan->lapdm_ch.lapdm_acch; + /* save the SACCH L1 header in the lchan struct for RSL MEAS RES */ + if (len < 2) { + LOGP(DL1P, LOGL_NOTICE, "SACCH with size %u<2 !?!\n", + len); + return -EINVAL; + } + /* Some brilliant engineer decided that the ordering of + * fields on the Um interface is different from the + * order of fields in RLS. See TS 04.04 (Chapter 7.2) + * vs. TS 08.58 (Chapter 9.3.10). */ + lchan->meas.l1_info[0] = data[0] << 3; + lchan->meas.l1_info[0] |= ((data[0] >> 5) & 1) << 2; + lchan->meas.l1_info[1] = data[1]; + lchan->meas.flags |= LC_UL_M_F_L1_VALID; + } else + le = &lchan->lapdm_ch.lapdm_dcch; + + /* if this is the first valid message after enabling Rx + * decryption, we have to enable Tx encryption */ + if (lchan->ciph_state == LCHAN_CIPH_RX_CONF) { + /* HACK: check if it's an I frame, in order to + * ignore some still buffered/queued UI frames received + * before decryption was enabled */ + if (data[0] == 0x01 && (data[1] & 0x01) == 0) { + l1sap_tx_ciph_req(trx, chan_nr, 1, 0); + } + } + + /* SDCCH, SACCH and FACCH all go to LAPDm */ + msgb_pull(msg, (msg->l2h - msg->data)); + msg->l1h = NULL; + lapdm_phsap_up(&l1sap->oph, le); + + /* don't free, because we forwarded data */ + return 1; } /* TCH received from bts model */ |