Osmocom Packet control Unit (PCU): Network-side GPRS (RLC/MAC); BTS- or BSC-colocated https://osmocom.org/projects/osmopcu
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osmo-pcu/src/gprs_bssgp_rim.c

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/* gprs_bssgp_pcu.cpp
*
* Copyright (C) 2021 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <osmocom/gprs/gprs_bssgp.h>
#include <osmocom/gprs/gprs_bssgp_rim.h>
#include <osmocom/core/msgb.h>
#include <osmocom/gsm/tlv.h>
#include <osmocom/gprs/gprs_ns.h>
#include <osmocom/core/prim.h>
#include <pcu_l1_if.h>
#include <gprs_rlcmac.h>
#include <bts.h>
#include "gprs_debug.h"
#include "gprs_pcu.h"
#include "bts.h"
#include "gprs_ms.h"
#include "nacc_fsm.h"
#define LOGPRIM(nsei, level, fmt, args...) \
LOGP(DRIM, level, "(NSEI=%u) " fmt, nsei, ## args)
static inline void gprs_ra_id_ci_to_cgi_ps(struct osmo_cell_global_id_ps *cgi_ps,
const struct gprs_ra_id *raid, uint16_t cid)
{
*cgi_ps = (struct osmo_cell_global_id_ps) {
.rai.lac.plmn.mcc = raid->mcc,
.rai.lac.plmn.mnc = raid->mnc,
.rai.lac.plmn.mnc_3_digits = raid->mnc_3_digits,
.rai.lac.lac = raid->lac,
.rai.rac = raid->rac,
.cell_identity = cid,
};
}
/* Mirror RIM routing information of a given PDU, see also 3GPP TS 48.018, section 8c.1.4.3 */
static void mirror_rim_routing_info(struct bssgp_ran_information_pdu *to_pdu,
const struct bssgp_ran_information_pdu *from_pdu)
{
memcpy(&to_pdu->routing_info_dest, &from_pdu->routing_info_src, sizeof(to_pdu->routing_info_dest));
memcpy(&to_pdu->routing_info_src, &from_pdu->routing_info_dest, sizeof(to_pdu->routing_info_src));
}
/* Fill NACC application container with data (cell identifier, sysinfo) */
#define SI_HDR_LEN 2
static void fill_app_cont_nacc(struct bssgp_ran_inf_app_cont_nacc *app_cont, const struct gprs_rlcmac_bts *bts)
{
struct bssgp_bvc_ctx *bctx = the_pcu->bssgp.bctx;
gprs_ra_id_ci_to_cgi_ps(&app_cont->reprt_cell, &bctx->ra_id, bctx->cell_id);
app_cont->num_si = 0;
/* Note: The BTS struct stores the system information including its pseudo header. The RIM application
* container defines the system information without pseudo header, so we need to chop it off. */
if (bts->si1_is_set) {
app_cont->si[app_cont->num_si] = bts->si1 + SI_HDR_LEN;
app_cont->num_si++;
}
if (bts->si3_is_set) {
app_cont->si[app_cont->num_si] = bts->si3 + SI_HDR_LEN;
app_cont->num_si++;
}
if (bts->si13_is_set) {
app_cont->si[app_cont->num_si] = bts->si13 + SI_HDR_LEN;
app_cont->num_si++;
}
/* Note: It is possible that the resulting PDU will not contain any system information, even if this is
* an unlikely case since the BTS immediately updates the system information after startup. The
* specification permits to send zero system information, see also: 3GPP TS 48.018 section 11.3.63.2.1 */
if (!bts->si1_is_set || !bts->si3_is_set || !bts->si13_is_set)
LOGP(DNACC, LOGL_INFO, "TX RAN INFO RESPONSE (NACC) %s: Some SI are missing:%s%s%s\n",
osmo_cgi_ps_name(&app_cont->reprt_cell),
bts->si1_is_set ? "" : " SI1",
bts->si3_is_set ? "" : " SI3",
bts->si13_is_set ? "" : " SI13");
}
/* Format a RAN INFORMATION PDU that contains the requested system information */
static void format_response_pdu(struct bssgp_ran_information_pdu *resp_pdu,
const struct bssgp_ran_information_pdu *req_pdu,
const struct gprs_rlcmac_bts *bts)
{
memset(resp_pdu, 0, sizeof(*resp_pdu));
mirror_rim_routing_info(resp_pdu, req_pdu);
resp_pdu->decoded.rim_cont = (struct bssgp_ran_inf_rim_cont) {
.app_id = BSSGP_RAN_INF_APP_ID_NACC,
.seq_num = 1, /* single report has only one message in response */
.pdu_ind = {
.pdu_type_ext = RIM_PDU_TYPE_SING_REP,
},
.prot_ver = 1,
};
fill_app_cont_nacc(&resp_pdu->decoded.rim_cont.u.app_cont_nacc, bts);
resp_pdu->decoded_present = true;
resp_pdu->rim_cont_iei = BSSGP_IE_RI_RIM_CONTAINER;
}
/* Format a RAN INFORMATION ERROR PDU */
static void format_response_pdu_err(struct bssgp_ran_information_pdu *resp_pdu,
const struct bssgp_ran_information_pdu *req_pdu)
{
memset(resp_pdu, 0, sizeof(*resp_pdu));
mirror_rim_routing_info(resp_pdu, req_pdu);
resp_pdu->decoded.err_rim_cont = (struct bssgp_ran_inf_err_rim_cont) {
.app_id = BSSGP_RAN_INF_APP_ID_NACC,
.prot_ver = 1,
.err_pdu = req_pdu->rim_cont,
.err_pdu_len = req_pdu->rim_cont_len,
};
resp_pdu->decoded_present = true;
resp_pdu->rim_cont_iei = BSSGP_IE_RI_ERROR_RIM_COINTAINER;
}
static int handle_ran_info_response_nacc(const struct bssgp_ran_inf_app_cont_nacc *nacc, struct gprs_rlcmac_bts *bts)
{
struct si_cache_value val;
struct si_cache_entry *entry;
struct llist_head *tmp;
int i;
LOGP(DRIM, LOGL_INFO, "Rx RAN-INFO cell=%s type=%sBCCH num_si=%d\n",
osmo_cgi_ps_name(&nacc->reprt_cell),
nacc->type_psi ? "P" : "", nacc->num_si);
val.type_psi = nacc->type_psi;
val.si_len = 0;
for (i = 0; i < nacc->num_si; i++) {
size_t len = val.type_psi ? BSSGP_RIM_PSI_LEN : BSSGP_RIM_SI_LEN;
memcpy(&val.si_buf[val.si_len], nacc->si[i], len);
val.si_len += len;
}
entry = si_cache_add(bts->pcu->si_cache, &nacc->reprt_cell, &val);
llist_for_each(tmp, bts_ms_list(bts)) {
struct GprsMs *ms = llist_entry(tmp, typeof(*ms), list);
if (ms->nacc && nacc_fsm_is_waiting_si_resolution(ms->nacc, &nacc->reprt_cell))
osmo_fsm_inst_dispatch(ms->nacc->fi, NACC_EV_RX_SI, entry);
}
return 0;
}
static int handle_ran_info_request(const struct bssgp_ran_information_pdu *pdu,
struct gprs_rlcmac_bts *bts, uint16_t nsei)
{
const struct bssgp_ran_inf_req_rim_cont *ri_req = &pdu->decoded.req_rim_cont;
const struct bssgp_ran_inf_req_app_cont_nacc *nacc_req;
struct bssgp_ran_information_pdu resp_pdu;
int rc;
/* Check if we support the application ID */
if (ri_req->app_id != BSSGP_RAN_INF_APP_ID_NACC) {
LOGPRIM(nsei, LOGL_ERROR,
"Rx RAN-INFO-REQ for cell %s with unknown/wrong application ID %s -- reject.\n",
osmo_cgi_ps_name(&bts->cgi_ps), bssgp_ran_inf_app_id_str(ri_req->app_id));
format_response_pdu_err(&resp_pdu, pdu);
rc = -ENOTSUP;
goto tx_ret;
}
nacc_req = &ri_req->u.app_cont_nacc;
rc = osmo_cgi_ps_cmp(&bts->cgi_ps, &nacc_req->reprt_cell);
if (rc != 0) {
LOGPRIM(nsei, LOGL_ERROR, "reporting cell in RIM application container %s "
"does not match destination cell in RIM routing info %s -- rejected.\n",
osmo_cgi_ps_name(&nacc_req->reprt_cell),
osmo_cgi_ps_name2(&bts->cgi_ps));
format_response_pdu_err(&resp_pdu, pdu);
} else {
LOGPRIM(nsei, LOGL_INFO, "Responding to RAN INFORMATION REQUEST %s ...\n",
osmo_cgi_ps_name(&nacc_req->reprt_cell));
format_response_pdu(&resp_pdu, pdu, bts);
}
tx_ret:
bssgp_tx_rim(&resp_pdu, nsei);
return rc;
}
static int handle_ran_info_response(const struct bssgp_ran_information_pdu *pdu, struct gprs_rlcmac_bts *bts)
{
const struct bssgp_ran_inf_rim_cont *ran_info = &pdu->decoded.rim_cont;
char ri_src_str[64];
/* Check if we support the application ID */
if (ran_info->app_id != BSSGP_RAN_INF_APP_ID_NACC) {
LOGP(DRIM, LOGL_ERROR,
"Rx RAN-INFO for cell %s with unknown/wrong application ID %s received -- reject.\n",
osmo_cgi_ps_name(&bts->cgi_ps), bssgp_ran_inf_app_id_str(ran_info->app_id));
return -1;
}
if (ran_info->app_err) {
LOGP(DRIM, LOGL_ERROR,
"%s Rx RAN-INFO with an app error! cause: %s\n",
bssgp_rim_ri_name_buf(ri_src_str, sizeof(ri_src_str), &pdu->routing_info_src),
bssgp_nacc_cause_str(ran_info->u.app_err_cont_nacc.nacc_cause));
return -1;
}
handle_ran_info_response_nacc(&ran_info->u.app_cont_nacc, bts);
return 0;
}
int handle_rim(struct osmo_bssgp_prim *bp)
{
struct msgb *msg = bp->oph.msg;
uint16_t nsei = msgb_nsei(msg);
struct bssgp_ran_information_pdu *pdu = &bp->u.rim_pdu;
struct bssgp_ran_information_pdu resp_pdu;
struct osmo_cell_global_id_ps dst_addr;
struct gprs_rlcmac_bts *bts;
OSMO_ASSERT (bp->oph.sap == SAP_BSSGP_RIM);
/* At the moment we only support GERAN, so we block all other network
* types here. */
if (pdu->routing_info_dest.discr != BSSGP_RIM_ROUTING_INFO_GERAN) {
LOGPRIM(nsei, LOGL_ERROR,
"Only GERAN supported, destination cell is not a GERAN cell -- rejected.\n");
return bssgp_tx_status(BSSGP_CAUSE_UNKN_RIM_AI, NULL, msg);
}
/* Check if the RIM pdu is really addressed to this PCU. In case we
* receive a RIM PDU for a cell that is not parented by this PCU we
* are supposed to reject it with a BSSGP STATUS.
* see also: 3GPP TS 48.018, section 8c.3.1.2 */
gprs_ra_id_ci_to_cgi_ps(&dst_addr, &pdu->routing_info_dest.geran.raid,
pdu->routing_info_dest.geran.cid);
bts = gprs_pcu_get_bts_by_cgi_ps(the_pcu, &dst_addr);
if (!bts) {
LOGPRIM(nsei, LOGL_ERROR, "Destination cell %s unknown to this pcu\n",
osmo_cgi_ps_name(&dst_addr));
return bssgp_tx_status(BSSGP_CAUSE_UNKN_DST, NULL, msg);
}
/* Check if the incoming RIM PDU is parseable, if not we must report
* an error to the controlling BSS 3GPP TS 48.018, 8c.3.4 and 8c.3.4.2 */
if (!pdu->decoded_present) {
LOGPRIM(nsei, LOGL_ERROR, "Erroneous RIM PDU received for cell %s -- reject.\n",
osmo_cgi_ps_name(&dst_addr));
format_response_pdu_err(&resp_pdu, pdu);
return 0;
}
/* Handle incoming RIM container */
switch (pdu->rim_cont_iei) {
case BSSGP_IE_RI_REQ_RIM_CONTAINER:
return handle_ran_info_request(pdu, bts, nsei);
case BSSGP_IE_RI_RIM_CONTAINER:
return handle_ran_info_response(pdu, bts);
case BSSGP_IE_RI_APP_ERROR_RIM_CONT:
case BSSGP_IE_RI_ACK_RIM_CONTAINER:
case BSSGP_IE_RI_ERROR_RIM_COINTAINER:
LOGPRIM(nsei, LOGL_ERROR, "RIM PDU not handled by this application\n");
return -EINVAL;
default:
/* This should never happen. If the RIM PDU is parsed correctly, then the rim_cont_iei will
* be set to one of the cases above and if parsing fails this switch statement is guarded
* by the check on decoded_present above */
OSMO_ASSERT(false);
}
return 0;
}