diff options
Diffstat (limited to 'include/osmocom/msc/sccp_ran.h')
| -rw-r--r-- | include/osmocom/msc/sccp_ran.h | 280 |
1 files changed, 280 insertions, 0 deletions
diff --git a/include/osmocom/msc/sccp_ran.h b/include/osmocom/msc/sccp_ran.h new file mode 100644 index 000000000..b7da314b2 --- /dev/null +++ b/include/osmocom/msc/sccp_ran.h @@ -0,0 +1,280 @@ +/* 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_nas_decode_cb(struct nas_dec_msg) msc_a_nas_enc(struct nas_enc_msg) + * ^ ^ . | + * | -Decode NAS- | . NAS v + * | | . ran_infra[type]->nas_encode(struct nas_enc_msg) + * nas_a_decode_l2() nas_iu_decode_l2() . | | + * ^ ^ . v v + * | | . nas_a_encode() nas_iu_encode() + * ran_infra[type]->nas_dec_l2() | | + * ^ | -Encode BSSAP/RANAP- | + * | v v + * msc_a_nas_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[]->nas_dec_l2(), which decodes the BSSAP or RANAP. + * - contained information is passed to msc_a_nas_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[]->nas_encode(), the nas_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[]->nas_dec_l2(), which decodes the BSSAP or RANAP. + * - contained information is passed to msc_a_nas_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[]->nas_encode(), the nas_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 <stdint.h> + +#include <osmocom/core/tdef.h> +#include <osmocom/gsm/gsm_utils.h> +#include <osmocom/gsm/gsm0808_utils.h> +#include <osmocom/sigtran/sccp_sap.h> + +#include <osmocom/msc/paging.h> + +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 : -1), 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 : -1), \ + 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. */ + enum reset_msg_type (* is_reset_msg )(const struct sccp_ran_inst *sri, const struct msgb *l2_cl); + + /* 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); |