| /* The MSC-T role implementation variant that forwards requests to/from a remote MSC. */ |
| /* |
| * (C) 2019 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de> |
| * 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 <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include <osmocom/core/fsm.h> |
| |
| #include <osmocom/msc/debug.h> |
| #include <osmocom/msc/gsm_data.h> |
| #include <osmocom/msc/msc_t_remote.h> |
| #include <osmocom/msc/msc_roles.h> |
| #include <osmocom/msc/msub.h> |
| #include <osmocom/msc/msc_t.h> |
| #include <osmocom/msc/e_link.h> |
| |
| static struct osmo_fsm msc_t_remote_fsm; |
| |
| static struct msc_t *msc_t_remote_priv(struct osmo_fsm_inst *fi) |
| { |
| OSMO_ASSERT(fi); |
| OSMO_ASSERT(fi->fsm == &msc_t_remote_fsm); |
| OSMO_ASSERT(fi->priv); |
| return fi->priv; |
| } |
| |
| /* The idea is that this msc_t role is event-compatible to the "real" msc_t.c FSM, but instead of acting on the events |
| * directly, it forwards the events to a remote MSC-T role, via E-over-GSUP. |
| * |
| * [MSC-A-----------------] [MSC-B-----------------] |
| * msc_a --> msc_t_remote ----GSUP---> msc_a_remote --> msc_t ---BSSMAP--> [BSS] |
| * you are here^ |
| */ |
| static int msc_t_remote_msg_down_to_remote_msc(struct msc_t *msc_t, |
| enum osmo_gsup_message_type message_type, |
| struct an_apdu *an_apdu) |
| { |
| struct osmo_gsup_message m; |
| struct e_link *e = msc_t->c.remote_to; |
| |
| if (!e) { |
| LOG_MSC_T_REMOTE(msc_t, LOGL_ERROR, "No E link to remote MSC, cannot send AN-APDU\n"); |
| return -1; |
| } |
| |
| if (e_prep_gsup_msg(e, &m)) { |
| LOG_MSC_T_REMOTE(msc_t, 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_T_REMOTE(msc_t, LOGL_ERROR, "Error composing E-interface GSUP message\n"); |
| return -1; |
| } |
| } |
| |
| return e_tx(e, &m); |
| } |
| |
| /* [MSC-A-----------------] [MSC-B-----------------] |
| * msc_a <-- msc_t_remote <---GSUP---- msc_a_remote <-- msc_t <--BSSMAP--- [BSS] |
| * you are here^ |
| */ |
| static int msc_t_remote_rx_gsup(struct msc_t *msc_t, const struct osmo_gsup_message *gsup_msg) |
| { |
| uint32_t event; |
| struct an_apdu an_apdu; |
| int rc; |
| |
| switch (gsup_msg->message_type) { |
| case OSMO_GSUP_MSGT_E_PROCESS_ACCESS_SIGNALLING_REQUEST: |
| event = MSC_A_EV_FROM_T_PROCESS_ACCESS_SIGNALLING_REQUEST; |
| break; |
| |
| case OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_ERROR: |
| case OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_RESULT: |
| event = MSC_A_EV_FROM_T_PREPARE_HANDOVER_RESPONSE; |
| break; |
| |
| case OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_REQUEST: |
| event = MSC_A_EV_FROM_T_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_t_clear(msc_t); |
| return 0; |
| |
| default: |
| LOG_MSC_T_REMOTE(msc_t, 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_t_remote <---GSUP---- msc_a_remote <-- msc_t <--BSSMAP--- [BSS] |
| * ^you are here |
| */ |
| gsup_msg_to_an_apdu(&an_apdu, gsup_msg); |
| rc = msub_role_dispatch(msc_t->c.msub, MSC_ROLE_A, event, &an_apdu); |
| if (an_apdu.msg) |
| msgb_free(an_apdu.msg); |
| return rc; |
| } |
| |
| static void msc_t_remote_fsm_ready(struct osmo_fsm_inst *fi, uint32_t event, void *data) |
| { |
| struct msc_t *msc_t = msc_t_remote_priv(fi); |
| struct an_apdu *an_apdu; |
| |
| switch (event) { |
| |
| case MSC_REMOTE_EV_RX_GSUP: |
| /* [MSC-A-----------------] [MSC-B-----------------] |
| * msc_a <-- msc_t_remote <---GSUP---- msc_a_remote <-- msc_t <--BSSMAP--- [BSS] |
| * you are here^ |
| */ |
| msc_t_remote_rx_gsup(msc_t, (const struct osmo_gsup_message*)data); |
| return; |
| |
| case MSC_T_EV_FROM_A_PREPARE_HANDOVER_REQUEST: |
| /* [MSC-A-----------------] [MSC-B-----------------] |
| * msc_a --> msc_t_remote ----GSUP---> going to create an msc_t if the request succeeds |
| * ^you are here |
| */ |
| an_apdu = data; |
| msc_t_remote_msg_down_to_remote_msc(msc_t, OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_REQUEST, an_apdu); |
| return; |
| |
| case MSC_T_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST: |
| /* [MSC-A-----------------] [MSC-B-----------------] |
| * msc_a --> msc_t_remote ----GSUP---> msc_a_remote --> msc_t ---BSSMAP--> [BSS] |
| * ^you are here |
| */ |
| an_apdu = data; |
| msc_t_remote_msg_down_to_remote_msc(msc_t, OSMO_GSUP_MSGT_E_FORWARD_ACCESS_SIGNALLING_REQUEST, an_apdu); |
| return; |
| |
| default: |
| OSMO_ASSERT(false); |
| } |
| } |
| |
| static void msc_t_remote_fsm_cleanup(struct osmo_fsm_inst *fi, enum osmo_fsm_term_cause cause) |
| { |
| struct msc_t *msc_t = msc_t_remote_priv(fi); |
| if (msc_t->c.remote_to) |
| msc_t_remote_msg_down_to_remote_msc(msc_t, OSMO_GSUP_MSGT_E_CLOSE, NULL); |
| } |
| |
| #define S(x) (1 << (x)) |
| |
| static const struct osmo_fsm_state msc_t_remote_fsm_states[] = { |
| /* An FSM instance always starts in state 0. Define one just to be able to state_chg out of it. Root reason is |
| * that we're using MSC_T_ST_* enum values from msc_t.c, but don't need the first |
| * MSC_T_ST_PENDING_FIRST_CO_INITIAL_MSG. */ |
| [0] = { |
| .name = "0", |
| .out_state_mask = 0 |
| | S(MSC_T_ST_WAIT_HO_COMPLETE) |
| , |
| }, |
| [MSC_T_ST_WAIT_HO_COMPLETE] = { |
| .name = "WAIT_HO_COMPLETE", |
| .action = msc_t_remote_fsm_ready, |
| .in_event_mask = 0 |
| | S(MSC_REMOTE_EV_RX_GSUP) |
| | S(MSC_T_EV_FROM_A_PREPARE_HANDOVER_REQUEST) |
| | S(MSC_T_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST) |
| , |
| }, |
| }; |
| |
| static struct osmo_fsm msc_t_remote_fsm = { |
| .name = "msc_t_remote", |
| .states = msc_t_remote_fsm_states, |
| .num_states = ARRAY_SIZE(msc_t_remote_fsm_states), |
| .log_subsys = DMSC, |
| .event_names = msc_t_fsm_event_names, |
| .cleanup = msc_t_remote_fsm_cleanup, |
| }; |
| |
| static __attribute__((constructor)) void msc_t_remote_fsm_init(void) |
| { |
| OSMO_ASSERT(osmo_fsm_register(&msc_t_remote_fsm) == 0); |
| } |
| |
| struct msc_t *msc_t_remote_alloc(struct msub *msub, struct ran_infra *ran, |
| const uint8_t *remote_msc_name, size_t remote_msc_name_len) |
| { |
| struct msc_t *msc_t; |
| |
| msub_role_alloc(msub, MSC_ROLE_T, &msc_t_remote_fsm, struct msc_t, ran); |
| msc_t = msub_msc_t(msub); |
| if (!msc_t) |
| return NULL; |
| |
| msc_t->c.remote_to = e_link_alloc(msub_net(msub)->gcm, msc_t->c.fi, remote_msc_name, remote_msc_name_len); |
| if (!msc_t->c.remote_to) { |
| LOG_MSC_T_REMOTE(msc_t, LOGL_ERROR, "Failed to set up E link over GSUP to remote MSC\n"); |
| msc_t_clear(msc_t); |
| return NULL; |
| } |
| |
| osmo_fsm_inst_state_chg(msc_t->c.fi, MSC_T_ST_WAIT_HO_COMPLETE, 0, 0); |
| return msc_t; |
| } |