/* The MSC-I role implementation variant that forwards requests to/from a remote MSC. */ /* * (C) 2019 by sysmocom - s.f.m.c. GmbH * All Rights Reserved * * SPDX-License-Identifier: AGPL-3.0+ * * Author: Neels Hofmeyr * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as published by * the Free Software Foundation; either version 3 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 Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see . */ #include #include #include #include #include #include #include #include static struct osmo_fsm msc_i_remote_fsm; static struct msc_i *msc_i_remote_priv(struct osmo_fsm_inst *fi) { OSMO_ASSERT(fi); OSMO_ASSERT(fi->fsm == &msc_i_remote_fsm); OSMO_ASSERT(fi->priv); return fi->priv; } /* The idea is that this msc_i role is event-compatible to the "real" msc_i.c FSM, but instead of acting on the events * directly, it forwards the events to a remote MSC-I role, via E-over-GSUP. * * [MSC-A-----------------] [MSC-B-----------------] * msc_a --> msc_i_remote ----GSUP---> msc_a_remote --> msc_i ---BSSMAP--> [BSS] * you are here^ */ static int msc_i_remote_msg_down_to_remote_msc(struct msc_i *msc_i, enum osmo_gsup_message_type message_type, struct an_apdu *an_apdu) { struct osmo_gsup_message m; struct e_link *e = msc_i->c.remote_to; if (!e) { LOG_MSC_I_REMOTE(msc_i, LOGL_ERROR, "No E link to remote MSC, cannot send AN-APDU\n"); return -1; } if (e_prep_gsup_msg(e, &m)) { LOG_MSC_I_REMOTE(msc_i, LOGL_ERROR, "Error composing E-interface GSUP message\n"); return -1; } m.message_type = message_type; if (an_apdu) { if (gsup_msg_assign_an_apdu(&m, an_apdu)) { LOG_MSC_I_REMOTE(msc_i, LOGL_ERROR, "Error composing E-interface GSUP message\n"); return -1; } } return e_tx(e, &m); } /* [MSC-A-----------------] [MSC-B-----------------] * msc_a <-- msc_i_remote <---GSUP---- msc_a_remote <-- msc_i <--BSSMAP--- [BSS] * you are here^ */ static int msc_i_remote_rx_gsup(struct msc_i *msc_i, const struct osmo_gsup_message *gsup_msg) { uint32_t event; struct an_apdu an_apdu; int rc; /* MSC_A_EV_FROM_I_COMPLETE_LAYER_3 will never occur with a remote MSC-I, since all Complete Layer 3 will happen * between a local MSC-A and local MSC-I roles. Only after an inter-MSC Handover will there possibly exist a * remote MSC-I, which is long after Complete Layer 3. */ switch (gsup_msg->message_type) { case OSMO_GSUP_MSGT_E_PROCESS_ACCESS_SIGNALLING_REQUEST: case OSMO_GSUP_MSGT_E_PREPARE_SUBSEQUENT_HANDOVER_REQUEST: event = MSC_A_EV_FROM_I_PROCESS_ACCESS_SIGNALLING_REQUEST; break; case OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_REQUEST: event = MSC_A_EV_FROM_I_SEND_END_SIGNAL_REQUEST; break; case OSMO_GSUP_MSGT_E_CLOSE: case OSMO_GSUP_MSGT_E_ABORT: case OSMO_GSUP_MSGT_E_ROUTING_ERROR: msc_i_clear(msc_i); return 0; default: LOG_MSC_I_REMOTE(msc_i, LOGL_ERROR, "Unhandled GSUP message type: %s\n", osmo_gsup_message_type_name(gsup_msg->message_type)); return -1; }; /* [MSC-A-----------------] [MSC-B-----------------] * msc_a <-- msc_i_remote <---GSUP---- msc_a_remote <-- msc_i <--BSSMAP--- [BSS] * ^you are here */ gsup_msg_to_an_apdu(&an_apdu, gsup_msg); rc = msub_role_dispatch(msc_i->c.msub, MSC_ROLE_A, event, &an_apdu); if (an_apdu.msg) msgb_free(an_apdu.msg); return rc; } static void msc_i_remote_fsm_ready(struct osmo_fsm_inst *fi, uint32_t event, void *data) { struct msc_i *msc_i = msc_i_remote_priv(fi); struct an_apdu *an_apdu; switch (event) { case MSC_REMOTE_EV_RX_GSUP: /* [MSC-A-----------------] [MSC-B-----------------] * msc_a <-- msc_i_remote <---GSUP---- msc_a_remote <-- msc_i <--BSSMAP--- [BSS] * you are here^ */ msc_i_remote_rx_gsup(msc_i, (const struct osmo_gsup_message*)data); return; case MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST: /* [MSC-A-----------------] [MSC-B-----------------] * msc_a --> msc_i_remote ----GSUP---> msc_a_remote --> msc_i ---BSSMAP--> [BSS] * ^you are here */ an_apdu = data; msc_i_remote_msg_down_to_remote_msc(msc_i, OSMO_GSUP_MSGT_E_FORWARD_ACCESS_SIGNALLING_REQUEST, an_apdu); return; case MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_RESULT: /* [MSC-A-----------------] [MSC-B-----------------] * msc_a --> msc_i_remote ----GSUP---> msc_a_remote --> msc_i ---BSSMAP--> [BSS] * ^you are here */ an_apdu = data; msc_i_remote_msg_down_to_remote_msc(msc_i, OSMO_GSUP_MSGT_E_PREPARE_SUBSEQUENT_HANDOVER_RESULT, an_apdu); return; case MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_ERROR: /* [MSC-A-----------------] [MSC-B-----------------] * msc_a --> msc_i_remote ----GSUP---> msc_a_remote --> msc_i ---BSSMAP--> [BSS] * ^you are here */ an_apdu = data; msc_i_remote_msg_down_to_remote_msc(msc_i, OSMO_GSUP_MSGT_E_PREPARE_SUBSEQUENT_HANDOVER_ERROR, an_apdu); return; case MSC_I_EV_FROM_A_SEND_END_SIGNAL_RESPONSE: /* [MSC-A-----------------] [MSC-B-----------------] * msc_a --> msc_i_remote ----GSUP---> msc_a_remote --> msc_i ---BSSMAP--> [BSS] * ^you are here */ an_apdu = data; msc_i_remote_msg_down_to_remote_msc(msc_i, OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_RESULT, an_apdu); return; default: OSMO_ASSERT(false); } } static void msc_i_remote_fsm_clearing_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state) { osmo_fsm_inst_term(fi, OSMO_FSM_TERM_REGULAR, fi); } static void msc_i_remote_fsm_cleanup(struct osmo_fsm_inst *fi, enum osmo_fsm_term_cause cause) { struct msc_i *msc_i = msc_i_remote_priv(fi); msc_i_remote_msg_down_to_remote_msc(msc_i, OSMO_GSUP_MSGT_E_CLOSE, NULL); } #define S(x) (1 << (x)) static const struct osmo_fsm_state msc_i_remote_fsm_states[] = { [MSC_I_ST_READY] = { .name = "READY", .action = msc_i_remote_fsm_ready, .in_event_mask = 0 | S(MSC_REMOTE_EV_RX_GSUP) | S(MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST) | S(MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_RESULT) | S(MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_ERROR) , .out_state_mask = 0 | S(MSC_I_ST_CLEARING) , }, [MSC_I_ST_CLEARING] = { .name = "CLEARING", .onenter = msc_i_remote_fsm_clearing_onenter, }, }; static struct osmo_fsm msc_i_remote_fsm = { .name = "msc_i_remote", .states = msc_i_remote_fsm_states, .num_states = ARRAY_SIZE(msc_i_remote_fsm_states), .log_subsys = DMSC, .event_names = msc_i_fsm_event_names, .cleanup = msc_i_remote_fsm_cleanup, }; static __attribute__((constructor)) void msc_i_remote_fsm_init(void) { OSMO_ASSERT(osmo_fsm_register(&msc_i_remote_fsm) == 0); } struct msc_i *msc_i_remote_alloc(struct msub *msub, struct ran_infra *ran, struct e_link *e) { struct msc_i *msc_i; msub_role_alloc(msub, MSC_ROLE_I, &msc_i_remote_fsm, struct msc_i, ran); msc_i = msub_msc_i(msub); if (!msc_i) return NULL; e_link_assign(e, msc_i->c.fi); if (!msc_i->c.remote_to) { LOG_MSC_I_REMOTE(msc_i, LOGL_ERROR, "Failed to set up E link over GSUP to remote MSC\n"); msc_i_clear(msc_i); return NULL; } return msc_i; }