/* gprs_bssgp_pcu.cpp * * Copyright (C) 2021 by sysmocom - s.f.m.c. GmbH * * 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 #include #include #include #include #include #include "gprs_debug.h" #include "gprs_pcu.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)); } /* 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; } /* Check if the application ID in the request PDU is actually BSSGP_RAN_INF_APP_ID_NACC */ static const enum bssgp_ran_inf_app_id *get_app_id(const struct bssgp_ran_information_pdu *pdu) { switch (pdu->rim_cont_iei) { case BSSGP_IE_RI_REQ_RIM_CONTAINER: return &pdu->decoded.req_rim_cont.app_id; case BSSGP_IE_RI_RIM_CONTAINER: return &pdu->decoded.rim_cont.app_id; case BSSGP_IE_RI_APP_ERROR_RIM_CONT: return &pdu->decoded.app_err_rim_cont.app_id; case BSSGP_IE_RI_ACK_RIM_CONTAINER: return &pdu->decoded.ack_rim_cont.app_id; case BSSGP_IE_RI_ERROR_RIM_COINTAINER: return &pdu->decoded.err_rim_cont.app_id; default: return NULL; } } /* Check if the application ID in the request PDU is of a certain type */ static bool match_app_id(const struct bssgp_ran_information_pdu *pdu, enum bssgp_ran_inf_app_id exp_app_id) { const enum bssgp_ran_inf_app_id *app_id = get_app_id(pdu); if (app_id && *app_id == exp_app_id) return true; return false; } 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, "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, "Errornous RIM PDU received -- rejected.\n"); format_response_pdu_err(&resp_pdu, pdu); return 0; } /* Check if the RIM container inside the incoming RIM PDU has the correct * application ID */ if (!match_app_id(pdu, BSSGP_RAN_INF_APP_ID_NACC)) { LOGPRIM(nsei, LOGL_ERROR, "RIM PDU with unknown/wrong application ID received -- rejected.\n"); 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: LOGPRIM(nsei, LOGL_NOTICE, "Responding to RAN INFORMATION REQUEST not yet implemented!\n"); break; case BSSGP_IE_RI_RIM_CONTAINER: LOGPRIM(nsei, LOGL_NOTICE, "Responding to RAN INFORMATION not yet implemented!\n"); break; 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; }