/* The RAN (Radio Access Network) side of an A- or Iu-connection, which is closely tied to an SCCP connection. * (as opposed to the NAS side.) * * The SCCP connection is located with the MSC-I role, while the MSC-A responsible for subscriber management may be at a * remote MSC behind an E-interface connection. In that case we need to forward the L2 messages over the E-interface and * the BSSAP or RANAP messages get decoded and interpreted at MSC-A. * * The life cycle of a DTAP message from RAN to MSC-A -- starting from the bottom left: * * ------------------>[ 3GPP TS 24.008 ]------------------->| * ^ (Request) (Response) | * | v * msc_a_up_l3() msc_a_tx_dtap_to_i(dtap_msgb) * ^ | * | v * msc_a_ran_decode_cb(struct ran_dec_msg) msc_a_ran_enc(struct ran_enc_msg) * ^ ^ . | * | -Decode NAS- | . NAS v * | | . ran_infra[type]->ran_encode(struct ran_enc_msg) * ran_a_decode_l2() ran_iu_decode_l2() . | | * ^ ^ . v v * | | . ran_a_encode() ran_iu_encode() * ran_infra[type]->ran_dec_l2() | | * ^ | -Encode BSSAP/RANAP- | * | v v * msc_a_ran_dec() msub_tx_an_apdu(from MSC_ROLE_A to MSC_ROLE_I) * ^ | * | MSC-A v * . msc_a FSM . . . . . . . . . . . . . . . . msc_a FSM . . . . . . . . . . * ^ | * | MSC_A_EV_FROM_I_PROCESS_ACCESS_SIGNALLING_REQUEST v * | data = an_apdu [possibly * | via GSUP * [possibly from remote MSC-A] * via GSUP | * to remote MSC-A] | MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST * ^ | data = an_apdu * | v * . msc_i FSM . . . . . . . . . . . . . . . . msc_i FSM . . . . . . . . . . * ^ MSC-I | * | MSC_EV_FROM_RAN_UP_L2 V * | data = an_apdu msc_i_down_l2(an_apdu->msg) * | | * ran_peer FSM V * ^ ran_conn_down_l2_co(); * | RAN_PEER_EV_MSG_UP_CO | * | data = struct ran_peer_ev_ctx | RAN_PEER_EV_MSG_DOWN_CO * | | data = struct ran_peer_ev_ctx * ran_peer_up_l2() V * (ran_infa->sccp_ran_ops.up_l2) ran_peer FSM * ^ ^ | * | | v * sccp_ran_sap_up() sccp_ran_down_l2_co(conn_id, msg) * ^ ^ | | * | | |SCCP| * |SCCP| v v * | | <------------------------------------------------------ * BSC RNC * | | * BTS NodeB * | | * MS UE * * sccp_ran: * - handles receiving of SCCP primitives from the SCCP layer. * - extracts L2 msg * - passes on L2 msg and conn_id by calling sccp_ran_ops.up_l2 == ran_peer_up_l2(). * * On Connection-Oriented *Initial* message * ======================================== * * ran_peer_up_l2() * - notices an unknown, new osmo_rat_type:conn_id and * - first creates an "empty" msub with new local MSC-I and MSC-A roles; * in this case always a *local* MSC-A (never remote on Initial messages). * - Passes the L2 msgb containing the BSSAP or RANAP as AN-APDU * in MSC_A_EV_FROM_I_COMPLETE_LAYER_3 to the MSC-A role FSM instance. * * MSC-A: * - Receives MSC_A_EV_FROM_I_COMPLETE_LAYER_3 AN-APDU, notices an_proto indicating BSSAP or RANAP. * - Passes L2 message to ran_infra[]->ran_dec_l2(), which decodes the BSSAP or RANAP. * - contained information is passed to msc_a_ran_decode_cb(). * - which msc_a starts Complete-L3 and VLR procedures, * - associates msub with a vlr_subscr, * - sends DTAP requests back down by calling msc_a_tx_dtap_to_i() (possibly other more specialized tx functions) * - according to ran_infra[]->ran_encode(), the ran_enc_msg gets encoded as BSSAP or RANAP. * - passes as AN-APDU to MSC-I in MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST signal. * * MSC-I, receiving AN-APDU from local MSC-A: * - feeds L2 msgb to the ran_peer FSM as RAN_PEER_EV_MSG_DOWN_CO, passing the SCCP conn_id. * * sccp_ran_down_l2_co() * - wraps in SCCP prim, * - sends down. * * * On (non-Initial) Connection-Oriented DTAP * ========================================= * * ran_peer_up_l2() * - notices an already known conn_id by looking up a matching osmo_rat_type:ran_conn. * - ran_conn already associated with an MSC-I role. * - Now forwards AN-APDU like above, only using MSC_A_EV_FROM_I_PROCESS_ACCESS_SIGNALLING_REQUEST. * * * MSC-A and MSC-I roles on separate MSC instances * =============================================== * * After inter-MSC handover, the MSC-I and MSC-A roles can be on separate MSC instances, typically physically distant / * possibly belonging to a different operator. This will never see Complete-L3. * Assuming that both instances are osmo-msc, then: * * At MSC-B: * initially, via GSUP: * - receives Handover Request from remote MSC-A, * - creates msub with local MSC-T role, * - sets up the ran_conn with a new SCCP conn_id, and waits for the MS/UE to show up. * - (fast-forward to successful Handover) * - MSC-T role becomes MSC-I for the remote MSC-A. * * Then for DTAP from the MS: * * sccp_ran: * - receives SCCP, * - extracts L2 and passes on to ran_peer_up_l2(). * * ran_peer_up_l2() * - notices an already known conn_id by looking up a matching ran_conn. * - ran_conn already associated with an MSC-I role and an msub. * - forwards AN-APDU in MSC_A_EV_FROM_I_PROCESS_ACCESS_SIGNALLING_REQUEST to the MSC-A role. * * At MSC-B, the "MSC-A role" is a *remote* implementation, * meaning there is an msc_a_remote FSM instance in MSC-B's msub: * * MSC-A-Remote: * - msc_a_remote receives MSC_A_EV_FROM_I_PROCESS_ACCESS_SIGNALLING_REQUEST, * - wraps AN-APDU in GSUP message, * - sends to remote MSC-A. * * At MSC-A: * Here, msub has a *remote* MSC-I role, * meaning it is an msc_i_remote FSM instance: * * MSC-I-Remote: * - msc_i_remote receives and decodes GSUP message, * - passes AN-APDU to MSC-A FSM instance via MSC_A_EV_FROM_I_PROCESS_ACCESS_SIGNALLING_REQUEST. * * MSC-A role: * - Receives MSC_A_EV_FROM_I_PROCESS_ACCESS_SIGNALLING_REQUEST, notices an_proto indicating BSSAP or RANAP. * - Passes L2 message to ran_infra[]->ran_dec_l2(), which decodes the BSSAP or RANAP. * - contained information is passed to msc_a_ran_decode_cb(). * - sends DTAP requests back down by calling msc_a_tx_dtap_to_i() (possibly other more specialized tx functions) * - according to ran_infra[]->ran_encode(), the ran_enc_msg gets encoded as BSSAP or RANAP. * - passes as AN-APDU to MSC-I in MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST signal. * * MSC-I-Remote: * - msc_i_remote wraps AN-APDU in GSUP message, * - sends to MSC-B * * At MSC-B: * MSC-A-Remote: * - msc_a_remote receives GSUP message, * - passes AN-APDU to msc_i in MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST. * * MSC-I: * - BSSAP or RANAP is indicated both by the AN-APDU an_proto, as well as the ran_conn state for that subscriber. * - feeds L2 msgb to the ran_peer FSM as RAN_PEER_EV_MSG_DOWN_CO, passing the SCCP conn_id. * * sccp_ran_down_l2_co() * - wraps in SCCP prim, * - sends down. * */ #pragma once #include #include #include #include #include #include struct msgb; struct ran_infra; struct sccp_ran_inst; #define LOG_SCCP_RAN_CO(sri, peer_addr, conn_id, level, fmt, args...) \ LOGP((sri) && (sri)->ran? (sri)->ran->log_subsys : DMSC, level, "(%s-%u%s%s) " fmt, \ osmo_rat_type_name((sri) && (sri)->ran ? (sri)->ran->type : OSMO_RAT_UNKNOWN), conn_id, \ peer_addr ? " from " : "", \ peer_addr ? osmo_sccp_inst_addr_name((sri)->sccp, peer_addr) : "", \ ## args) #define LOG_SCCP_RAN_CL_CAT(sri, peer_addr, subsys, level, fmt, args...) \ LOGP(subsys, level, "(%s%s%s) " fmt, \ osmo_rat_type_name((sri) && (sri)->ran ? (sri)->ran->type : OSMO_RAT_UNKNOWN), \ peer_addr ? " from " : "", \ peer_addr ? osmo_sccp_inst_addr_name((sri)->sccp, peer_addr) : "", \ ## args) #define LOG_SCCP_RAN_CL(sri, peer_addr, level, fmt, args...) \ LOG_SCCP_RAN_CL_CAT(sri, peer_addr, (sri) && (sri)->ran? (sri)->ran->log_subsys : DMSC, level, fmt, ##args) #define LOG_SCCP_RAN_CAT(sri, subsys, level, fmt, args...) \ LOG_SCCP_RAN_CL_CAT(sri, NULL, subsys, level, fmt, ##args) #define LOG_SCCP_RAN(sri, level, fmt, args...) \ LOG_SCCP_RAN_CL(sri, NULL, level, fmt, ##args) extern struct osmo_tdef g_sccp_tdefs[]; enum reset_msg_type { SCCP_RAN_MSG_NON_RESET = 0, SCCP_RAN_MSG_RESET, SCCP_RAN_MSG_RESET_ACK, }; struct sccp_ran_ops { /* Implemented to receive L2 messages (e.g. BSSAP or RANAP passed to ran_peer). * - ConnectionLess messages: co = false, calling_addr != NULL, conn_id == 0; * - ConnectionOriented Initial messages: co = true, calling_addr != NULL; * - ConnectionOriented non-Initial messages: co = true, calling_addr == NULL; */ int (* up_l2 )(struct sccp_ran_inst *sri, const struct osmo_sccp_addr *calling_addr, bool co, uint32_t conn_id, struct msgb *l2); /* Implemented to finally remove a connection state. Last event in a connection-oriented exchange. If the * N-DISCONNECT contained l2 data, it was dispatched via up_l2() before this is called. */ void (* disconnect )(struct sccp_ran_inst *sri, uint32_t conn_id); /* Return whether the given l2_cl message is a RESET, RESET ACKNOWLEDGE, or RESET-unrelated message. * This callback is stored in struct sccp_ran_inst to provide RESET handling to the caller (ran_peer), * it is not used in sccp_ran.c. * In supports_osmux, return 0 for no information, 1 for support detected, -1 for non-support detected. */ enum reset_msg_type (* is_reset_msg )(const struct sccp_ran_inst *sri, struct osmo_fsm_inst *log_fi, struct msgb *l2_cl, int *supports_osmux); /* Return a RESET or RESET ACK message for this RAN type. * This callback is stored in struct sccp_ran_inst to provide RESET handling to the caller (ran_peer), * it is not used in sccp_ran.c. */ struct msgb* (* make_reset_msg )(const struct sccp_ran_inst *sri, enum reset_msg_type); /* Return a PAGING message towards the given Cell Identifier, to page for the given TMSI or IMSI. * Page for TMSI if TMSI != GSM_RESERVED_TMSI, otherwise page for IMSI. */ struct msgb* (* make_paging_msg )(const struct sccp_ran_inst *sri, const struct gsm0808_cell_id *page_cell_id, const char *imsi, uint32_t tmsi, enum paging_cause cause); /* Return a human printable name for the msgb */ const char* (* msg_name )(const struct sccp_ran_inst *sri, const struct msgb *l2); }; struct sccp_ran_inst { struct ran_infra *ran; struct osmo_sccp_instance *sccp; struct osmo_sccp_user *scu; struct osmo_sccp_addr local_sccp_addr; struct llist_head ran_peers; struct llist_head ran_conns; void *user_data; /* Compatibility with legacy osmo-hnbgw that was unable to properly handle RESET messages. Set to 'false' to * require proper RESET procedures, set to 'true' to implicitly put a ran_peer in RAN_PEER_ST_READY upon the * first CO message. Default is false = be strict. */ bool ignore_missing_reset; }; struct sccp_ran_inst *sccp_ran_init(void *talloc_ctx, struct osmo_sccp_instance *sccp, enum osmo_sccp_ssn ssn, const char *sccp_user_name, struct ran_infra *ran, void *user_data); int sccp_ran_down_l2_co_initial(struct sccp_ran_inst *sri, const struct osmo_sccp_addr *called_addr, uint32_t conn_id, struct msgb *l2); int sccp_ran_down_l2_co(struct sccp_ran_inst *sri, uint32_t conn_id, struct msgb *l2); int sccp_ran_down_l2_cl(struct sccp_ran_inst *sri, const struct osmo_sccp_addr *called_addr, struct msgb *l2); int sccp_ran_disconnect(struct sccp_ran_inst *ran, uint32_t conn_id, uint32_t cause);