| /* The MSC-A role implementation variant that forwards requests to/from a remote MSC. */ |
| /* |
| * (C) 2019 by sysmocom - s.f.m.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 <inttypes.h> |
| |
| #include <osmocom/core/fsm.h> |
| #include <osmocom/gsm/gsup.h> |
| |
| #include <osmocom/msc/debug.h> |
| #include <osmocom/msc/gsm_data.h> |
| #include <osmocom/msc/msc_a_remote.h> |
| #include <osmocom/msc/msc_roles.h> |
| #include <osmocom/msc/msub.h> |
| #include <osmocom/msc/msc_a.h> |
| #include <osmocom/msc/msc_t.h> |
| #include <osmocom/msc/e_link.h> |
| #include <osmocom/msc/vlr.h> |
| #include <osmocom/msc/ran_peer.h> |
| |
| static struct osmo_fsm msc_a_remote_fsm; |
| |
| static struct msc_a *msc_a_remote_priv(struct osmo_fsm_inst *fi) |
| { |
| OSMO_ASSERT(fi); |
| OSMO_ASSERT(fi->fsm == &msc_a_remote_fsm); |
| OSMO_ASSERT(fi->priv); |
| return fi->priv; |
| } |
| |
| /* The idea is that this msc_a role is event-compatible to the "real" msc_a.c FSM, but instead of acting on the events |
| * directly, it forwards the events to a remote MSC-A role, via E-over-GSUP. |
| * |
| * [MSC-A---------------------] [MSC-B---------------------] |
| * msc_a <-- msc_{i,t}_remote <---GSUP---- msc_a_remote <-- msc_{i,t} <--BSSMAP--- [BSS] |
| * ^you are here |
| */ |
| static int msc_a_remote_msg_up_to_remote_msc(struct msc_a *msc_a, |
| enum msc_role from_role, |
| enum osmo_gsup_message_type message_type, |
| struct an_apdu *an_apdu) |
| { |
| struct osmo_gsup_message m; |
| struct e_link *e = msc_a->c.remote_to; |
| |
| if (!e) { |
| LOG_MSC_A_REMOTE(msc_a, LOGL_ERROR, "No E link to remote MSC, cannot send AN-APDU\n"); |
| return -1; |
| } |
| |
| if (e_prep_gsup_msg(e, &m)) { |
| LOG_MSC_A_REMOTE(msc_a, 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_A_REMOTE(msc_a, 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 void msc_a_remote_rx_gsup_to_msc_t(struct msc_a *msc_a, const struct osmo_gsup_message *gsup_msg) |
| { |
| uint32_t event; |
| struct an_apdu an_apdu; |
| |
| switch (gsup_msg->message_type) { |
| case OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_REQUEST: |
| event = MSC_T_EV_FROM_A_PREPARE_HANDOVER_REQUEST; |
| break; |
| |
| case OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_REQUEST: |
| case OSMO_GSUP_MSGT_E_FORWARD_ACCESS_SIGNALLING_REQUEST: |
| event = MSC_T_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST; |
| break; |
| |
| case OSMO_GSUP_MSGT_E_CLOSE: |
| case OSMO_GSUP_MSGT_E_ABORT: |
| case OSMO_GSUP_MSGT_E_ROUTING_ERROR: |
| /* TODO: maybe some non-"normal" release with error cause? */ |
| msc_a_release_cn(msc_a); |
| return; |
| |
| default: |
| LOG_MSC_A_REMOTE(msc_a, LOGL_ERROR, "Unhandled GSUP message type: %s\n", |
| osmo_gsup_message_type_name(gsup_msg->message_type)); |
| return; |
| }; |
| |
| gsup_msg_to_an_apdu(&an_apdu, gsup_msg); |
| msub_role_dispatch(msc_a->c.msub, MSC_ROLE_T, event, &an_apdu); |
| if (an_apdu.msg) |
| msgb_free(an_apdu.msg); |
| } |
| |
| /* [MSC-A-----------------] [MSC-B-----------------] |
| * msc_a --> msc_i_remote ----GSUP---> msc_a_remote --> msc_i ---BSSMAP--> [BSS] |
| * ^you are here |
| */ |
| static void msc_a_remote_rx_gsup_to_msc_i(struct msc_a *msc_a, const struct osmo_gsup_message *gsup_msg) |
| { |
| uint32_t event; |
| struct an_apdu an_apdu; |
| |
| switch (gsup_msg->message_type) { |
| case OSMO_GSUP_MSGT_E_FORWARD_ACCESS_SIGNALLING_REQUEST: |
| event = MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST; |
| break; |
| |
| case OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_ERROR: |
| case OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_RESULT: |
| event = MSC_I_EV_FROM_A_SEND_END_SIGNAL_RESPONSE; |
| break; |
| |
| case OSMO_GSUP_MSGT_E_PREPARE_SUBSEQUENT_HANDOVER_RESULT: |
| case OSMO_GSUP_MSGT_E_PREPARE_SUBSEQUENT_HANDOVER_ERROR: |
| event = MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_RESULT; |
| break; |
| |
| case OSMO_GSUP_MSGT_E_CLOSE: |
| case OSMO_GSUP_MSGT_E_ABORT: |
| case OSMO_GSUP_MSGT_E_ROUTING_ERROR: |
| /* TODO: maybe some non-"normal" release with error cause? */ |
| msc_a_release_cn(msc_a); |
| return; |
| |
| default: |
| LOG_MSC_A_REMOTE(msc_a, LOGL_ERROR, "Unhandled GSUP message type: %s\n", |
| osmo_gsup_message_type_name(gsup_msg->message_type)); |
| return; |
| }; |
| |
| gsup_msg_to_an_apdu(&an_apdu, gsup_msg); |
| msub_role_dispatch(msc_a->c.msub, MSC_ROLE_I, event, &an_apdu); |
| if (an_apdu.msg) |
| msgb_free(an_apdu.msg); |
| } |
| |
| static void msc_a_remote_send_handover_failure(struct msc_a *msc_a, enum gsm0808_cause cause) |
| { |
| struct ran_msg ran_enc_msg = { |
| .msg_type = RAN_MSG_HANDOVER_FAILURE, |
| .handover_failure = { |
| .cause = cause, |
| }, |
| }; |
| struct an_apdu an_apdu = { |
| .an_proto = msc_a->c.ran->an_proto, |
| .msg = msc_role_ran_encode(msc_a->c.fi, &ran_enc_msg), |
| }; |
| if (!an_apdu.msg) |
| return; |
| |
| msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_T, OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_ERROR, &an_apdu); |
| } |
| |
| /* [MSC-A---------------------] [MSC-B---------------------] |
| * msc_a --> msc_{i,t}_remote ----GSUP---> msc_a_remote --> msc_{i,t} ---BSSMAP--> [BSS] |
| * ^you are here |
| */ |
| static void msc_a_remote_rx_gsup(struct msc_a *msc_a, const struct osmo_gsup_message *gsup_msg) |
| { |
| struct msc_t *msc_t = msc_a_msc_t(msc_a); |
| struct msc_i *msc_i = msc_a_msc_i(msc_a); |
| |
| /* If starting a new Handover, this subscriber *must* be new and completely unattached. Create a new msc_t role |
| * to receive below event. */ |
| if (gsup_msg->message_type == OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_REQUEST) { |
| if (msc_t || msc_i) { |
| LOG_MSC_A_REMOTE_CAT(msc_a, DLGSUP, LOGL_ERROR, |
| "Already have an MSC-T or -I role, cannot Rx %s from remote MSC\n", |
| osmo_gsup_message_type_name(gsup_msg->message_type)); |
| msc_a_remote_send_handover_failure(msc_a, GSM0808_CAUSE_EQUIPMENT_FAILURE); |
| return; |
| } |
| |
| msc_t = msc_t_alloc_without_ran_peer(msc_a->c.msub, msc_a->c.ran); |
| } |
| |
| /* We are on a remote MSC-B. If an msub has an MSC-T role, this is the remote target of a handover, and all |
| * messages from MSC-A *must* be intended for the MSC-T role. As soon as the Handover is successful, the MSC-T |
| * role disappears and an MSC-I role appears. */ |
| if (msc_t) { |
| LOG_MSC_A_REMOTE_CAT(msc_a, DLGSUP, LOGL_DEBUG, "Routing to MSC-T: %s\n", |
| osmo_gsup_message_type_name(gsup_msg->message_type)); |
| msc_a_remote_rx_gsup_to_msc_t(msc_a, gsup_msg); |
| } else if (msc_i) { |
| LOG_MSC_A_REMOTE_CAT(msc_a, DLGSUP, LOGL_DEBUG, "Routing to MSC-I: %s\n", |
| osmo_gsup_message_type_name(gsup_msg->message_type)); |
| msc_a_remote_rx_gsup_to_msc_i(msc_a, gsup_msg); |
| } else { |
| LOG_MSC_A_REMOTE_CAT(msc_a, DLGSUP, LOGL_ERROR, |
| "No MSC-T nor MSC-I role present, cannot Rx GSUP %s\n", |
| osmo_gsup_message_type_name(gsup_msg->message_type)); |
| } |
| } |
| |
| static void msc_a_remote_fsm_communicating(struct osmo_fsm_inst *fi, uint32_t event, void *data) |
| { |
| struct msc_a *msc_a = msc_a_remote_priv(fi); |
| struct an_apdu *an_apdu; |
| |
| switch (event) { |
| |
| case MSC_REMOTE_EV_RX_GSUP: |
| /* [MSC-A---------------------] [MSC-B---------------------] |
| * msc_a --> msc_{i,t}_remote ----GSUP---> msc_a_remote --> msc_{i,t} ---BSSMAP--> [BSS] |
| * ^you are here |
| */ |
| msc_a_remote_rx_gsup(msc_a, (const struct osmo_gsup_message*)data); |
| return; |
| |
| /* For all remaining cases: |
| * [MSC-A---------------------] [MSC-B---------------------] |
| * msc_a <-- msc_{i,t}_remote <---GSUP---- msc_a_remote <-- msc_{i,t} <--BSSMAP--- [BSS] |
| * you are here^ |
| */ |
| |
| case MSC_A_EV_FROM_I_PROCESS_ACCESS_SIGNALLING_REQUEST: |
| an_apdu = data; |
| msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_I, |
| OSMO_GSUP_MSGT_E_PROCESS_ACCESS_SIGNALLING_REQUEST, an_apdu); |
| return; |
| |
| case MSC_A_EV_FROM_I_PREPARE_SUBSEQUENT_HANDOVER_REQUEST: |
| an_apdu = data; |
| msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_I, |
| OSMO_GSUP_MSGT_E_PREPARE_SUBSEQUENT_HANDOVER_REQUEST, an_apdu); |
| return; |
| |
| case MSC_A_EV_FROM_I_SEND_END_SIGNAL_REQUEST: |
| an_apdu = data; |
| msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_I, |
| OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_REQUEST, an_apdu); |
| return; |
| |
| case MSC_A_EV_FROM_T_PREPARE_HANDOVER_RESPONSE: |
| an_apdu = data; |
| msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_T, |
| OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_RESULT, an_apdu); |
| return; |
| |
| case MSC_A_EV_FROM_T_PREPARE_HANDOVER_FAILURE: |
| an_apdu = data; |
| msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_T, |
| OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_ERROR, an_apdu); |
| return; |
| |
| case MSC_A_EV_FROM_T_PROCESS_ACCESS_SIGNALLING_REQUEST: |
| an_apdu = data; |
| msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_T, |
| OSMO_GSUP_MSGT_E_PROCESS_ACCESS_SIGNALLING_REQUEST, an_apdu); |
| return; |
| |
| case MSC_A_EV_FROM_T_SEND_END_SIGNAL_REQUEST: |
| an_apdu = data; |
| msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_T, |
| OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_REQUEST, an_apdu); |
| return; |
| |
| case MSC_A_EV_CN_CLOSE: |
| case MSC_A_EV_MO_CLOSE: |
| osmo_fsm_inst_state_chg(msc_a->c.fi, MSC_A_ST_RELEASING, 0, 0); |
| return; |
| |
| default: |
| OSMO_ASSERT(false); |
| } |
| } |
| |
| static void msc_a_remote_fsm_releasing_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state) |
| { |
| osmo_fsm_inst_term(fi, OSMO_FSM_TERM_REGULAR, fi); |
| } |
| |
| static void msc_a_remote_fsm_cleanup(struct osmo_fsm_inst *fi, enum osmo_fsm_term_cause cause) |
| { |
| struct msc_a *msc_a = msc_a_remote_priv(fi); |
| if (msc_a->c.msub->role[MSC_ROLE_I]) |
| msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_I, OSMO_GSUP_MSGT_E_CLOSE, NULL); |
| if (msc_a->c.msub->role[MSC_ROLE_T]) |
| msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_T, OSMO_GSUP_MSGT_E_CLOSE, NULL); |
| } |
| |
| #define S(x) (1 << (x)) |
| |
| /* FSM events are by definition compatible with msc_a_fsm. States could be a separate enum, but so that |
| * msc_a_is_accepted() also works on remote msc_a, this FSM shares state numbers with the msc_a_fsm_states. */ |
| static const struct osmo_fsm_state msc_a_remote_fsm_states[] = { |
| /* Whichever MSC_A_ST would be the first for the real MSC-A implementation, a fresh FSM instance will start in |
| * state == 0 and we just need to be able to transition out of it. */ |
| [0] = { |
| .name = "INIT-REMOTE", |
| .out_state_mask = 0 |
| | S(MSC_A_ST_COMMUNICATING) |
| | S(MSC_A_ST_RELEASING) |
| , |
| }, |
| [MSC_A_ST_COMMUNICATING] = { |
| .name = "COMMUNICATING", |
| .action = msc_a_remote_fsm_communicating, |
| .in_event_mask = 0 |
| | S(MSC_REMOTE_EV_RX_GSUP) |
| | S(MSC_A_EV_FROM_I_PROCESS_ACCESS_SIGNALLING_REQUEST) |
| | S(MSC_A_EV_FROM_I_PREPARE_SUBSEQUENT_HANDOVER_REQUEST) |
| | S(MSC_A_EV_FROM_I_SEND_END_SIGNAL_REQUEST) |
| | S(MSC_A_EV_FROM_T_PREPARE_HANDOVER_RESPONSE) |
| | S(MSC_A_EV_FROM_T_PREPARE_HANDOVER_FAILURE) |
| | S(MSC_A_EV_FROM_T_PROCESS_ACCESS_SIGNALLING_REQUEST) |
| | S(MSC_A_EV_FROM_T_SEND_END_SIGNAL_REQUEST) |
| | S(MSC_A_EV_CN_CLOSE) |
| | S(MSC_A_EV_MO_CLOSE) |
| , |
| .out_state_mask = 0 |
| | S(MSC_A_ST_RELEASING) |
| , |
| }, |
| [MSC_A_ST_RELEASING] = { |
| .name = "RELEASING", |
| .onenter = msc_a_remote_fsm_releasing_onenter, |
| }, |
| }; |
| |
| static struct osmo_fsm msc_a_remote_fsm = { |
| .name = "msc_a_remote", |
| .states = msc_a_remote_fsm_states, |
| .num_states = ARRAY_SIZE(msc_a_remote_fsm_states), |
| .log_subsys = DMSC, |
| .event_names = msc_a_fsm_event_names, |
| .cleanup = msc_a_remote_fsm_cleanup, |
| }; |
| |
| static __attribute__((constructor)) void msc_a_remote_fsm_init(void) |
| { |
| OSMO_ASSERT(osmo_fsm_register(&msc_a_remote_fsm) == 0); |
| } |
| |
| struct msc_a *msc_a_remote_alloc(struct msub *msub, struct ran_infra *ran, |
| const uint8_t *remote_msc_name, size_t remote_msc_name_len) |
| { |
| struct msc_a *msc_a; |
| |
| msub_role_alloc(msub, MSC_ROLE_A, &msc_a_remote_fsm, struct msc_a, ran); |
| msc_a = msub_msc_a(msub); |
| if (!msc_a) { |
| LOG_MSUB(msub, LOGL_ERROR, "Error setting up MSC-A remote role\n"); |
| return NULL; |
| } |
| |
| msc_a->c.remote_to = e_link_alloc(msub_net(msub)->gcm, msc_a->c.fi, remote_msc_name, remote_msc_name_len); |
| if (!msc_a->c.remote_to) { |
| LOG_MSC_A_REMOTE(msc_a, LOGL_ERROR, "Failed to set up E link\n"); |
| msc_a_release_cn(msc_a); |
| return NULL; |
| } |
| |
| msc_a_update_id(msc_a); |
| |
| /* Immediately get out of state 0. */ |
| osmo_fsm_inst_state_chg(msc_a->c.fi, MSC_A_ST_COMMUNICATING, 0, 0); |
| |
| return msc_a; |
| } |