227 lines
7.0 KiB
C
227 lines
7.0 KiB
C
/* The MSC-T role implementation variant that forwards requests to/from a remote MSC. */
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/*
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* (C) 2019 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de>
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* All Rights Reserved
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*
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* SPDX-License-Identifier: AGPL-3.0+
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*
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* Author: Neels Hofmeyr
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <osmocom/core/fsm.h>
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#include <osmocom/msc/debug.h>
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#include <osmocom/msc/gsm_data.h>
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#include <osmocom/msc/msc_t_remote.h>
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#include <osmocom/msc/msc_roles.h>
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#include <osmocom/msc/msub.h>
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#include <osmocom/msc/msc_t.h>
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#include <osmocom/msc/e_link.h>
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static struct osmo_fsm msc_t_remote_fsm;
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static struct msc_t *msc_t_remote_priv(struct osmo_fsm_inst *fi)
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{
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OSMO_ASSERT(fi);
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OSMO_ASSERT(fi->fsm == &msc_t_remote_fsm);
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OSMO_ASSERT(fi->priv);
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return fi->priv;
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}
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/* 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
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* directly, it forwards the events to a remote MSC-T role, via E-over-GSUP.
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*
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* [MSC-A-----------------] [MSC-B-----------------]
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* msc_a --> msc_t_remote ----GSUP---> msc_a_remote --> msc_t ---BSSMAP--> [BSS]
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* you are here^
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*/
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static int msc_t_remote_msg_down_to_remote_msc(struct msc_t *msc_t,
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enum osmo_gsup_message_type message_type,
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struct an_apdu *an_apdu)
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{
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struct osmo_gsup_message m;
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struct e_link *e = msc_t->c.remote_to;
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if (!e) {
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LOG_MSC_T_REMOTE(msc_t, LOGL_ERROR, "No E link to remote MSC, cannot send AN-APDU\n");
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return -1;
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}
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if (e_prep_gsup_msg(e, &m)) {
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LOG_MSC_T_REMOTE(msc_t, LOGL_ERROR, "Error composing E-interface GSUP message\n");
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return -1;
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}
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m.message_type = message_type;
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if (an_apdu) {
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if (gsup_msg_assign_an_apdu(&m, an_apdu)) {
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LOG_MSC_T_REMOTE(msc_t, LOGL_ERROR, "Error composing E-interface GSUP message\n");
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return -1;
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}
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}
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return e_tx(e, &m);
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}
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/* [MSC-A-----------------] [MSC-B-----------------]
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* msc_a <-- msc_t_remote <---GSUP---- msc_a_remote <-- msc_t <--BSSMAP--- [BSS]
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* you are here^
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*/
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static int msc_t_remote_rx_gsup(struct msc_t *msc_t, const struct osmo_gsup_message *gsup_msg)
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{
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uint32_t event;
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struct an_apdu an_apdu;
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int rc;
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switch (gsup_msg->message_type) {
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case OSMO_GSUP_MSGT_E_PROCESS_ACCESS_SIGNALLING_REQUEST:
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event = MSC_A_EV_FROM_T_PROCESS_ACCESS_SIGNALLING_REQUEST;
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break;
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case OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_ERROR:
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case OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_RESULT:
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event = MSC_A_EV_FROM_T_PREPARE_HANDOVER_RESPONSE;
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break;
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case OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_REQUEST:
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event = MSC_A_EV_FROM_T_SEND_END_SIGNAL_REQUEST;
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break;
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case OSMO_GSUP_MSGT_E_CLOSE:
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case OSMO_GSUP_MSGT_E_ABORT:
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case OSMO_GSUP_MSGT_E_ROUTING_ERROR:
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msc_t_clear(msc_t);
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return 0;
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default:
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LOG_MSC_T_REMOTE(msc_t, LOGL_ERROR, "Unhandled GSUP message type: %s\n",
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osmo_gsup_message_type_name(gsup_msg->message_type));
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return -1;
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};
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/* [MSC-A-----------------] [MSC-B-----------------]
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* msc_a <-- msc_t_remote <---GSUP---- msc_a_remote <-- msc_t <--BSSMAP--- [BSS]
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* ^you are here
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*/
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gsup_msg_to_an_apdu(&an_apdu, gsup_msg);
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rc = msub_role_dispatch(msc_t->c.msub, MSC_ROLE_A, event, &an_apdu);
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if (an_apdu.msg)
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msgb_free(an_apdu.msg);
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return rc;
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}
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static void msc_t_remote_fsm_ready(struct osmo_fsm_inst *fi, uint32_t event, void *data)
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{
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struct msc_t *msc_t = msc_t_remote_priv(fi);
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struct an_apdu *an_apdu;
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switch (event) {
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case MSC_REMOTE_EV_RX_GSUP:
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/* [MSC-A-----------------] [MSC-B-----------------]
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* msc_a <-- msc_t_remote <---GSUP---- msc_a_remote <-- msc_t <--BSSMAP--- [BSS]
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* you are here^
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*/
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msc_t_remote_rx_gsup(msc_t, (const struct osmo_gsup_message*)data);
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return;
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case MSC_T_EV_FROM_A_PREPARE_HANDOVER_REQUEST:
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/* [MSC-A-----------------] [MSC-B-----------------]
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* msc_a --> msc_t_remote ----GSUP---> going to create an msc_t if the request succeeds
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* ^you are here
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*/
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an_apdu = data;
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msc_t_remote_msg_down_to_remote_msc(msc_t, OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_REQUEST, an_apdu);
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return;
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case MSC_T_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST:
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/* [MSC-A-----------------] [MSC-B-----------------]
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* msc_a --> msc_t_remote ----GSUP---> msc_a_remote --> msc_t ---BSSMAP--> [BSS]
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* ^you are here
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*/
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an_apdu = data;
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msc_t_remote_msg_down_to_remote_msc(msc_t, OSMO_GSUP_MSGT_E_FORWARD_ACCESS_SIGNALLING_REQUEST, an_apdu);
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return;
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default:
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OSMO_ASSERT(false);
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}
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}
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static void msc_t_remote_fsm_cleanup(struct osmo_fsm_inst *fi, enum osmo_fsm_term_cause cause)
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{
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struct msc_t *msc_t = msc_t_remote_priv(fi);
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if (msc_t->c.remote_to)
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msc_t_remote_msg_down_to_remote_msc(msc_t, OSMO_GSUP_MSGT_E_CLOSE, NULL);
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}
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#define S(x) (1 << (x))
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static const struct osmo_fsm_state msc_t_remote_fsm_states[] = {
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/* An FSM instance always starts in state 0. Define one just to be able to state_chg out of it. Root reason is
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* that we're using MSC_T_ST_* enum values from msc_t.c, but don't need the first
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* MSC_T_ST_PENDING_FIRST_CO_INITIAL_MSG. */
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[0] = {
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.name = "0",
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.out_state_mask = 0
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| S(MSC_T_ST_WAIT_HO_COMPLETE)
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,
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},
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[MSC_T_ST_WAIT_HO_COMPLETE] = {
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.name = "WAIT_HO_COMPLETE",
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.action = msc_t_remote_fsm_ready,
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.in_event_mask = 0
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| S(MSC_REMOTE_EV_RX_GSUP)
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| S(MSC_T_EV_FROM_A_PREPARE_HANDOVER_REQUEST)
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| S(MSC_T_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST)
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,
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},
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};
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static struct osmo_fsm msc_t_remote_fsm = {
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.name = "msc_t_remote",
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.states = msc_t_remote_fsm_states,
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.num_states = ARRAY_SIZE(msc_t_remote_fsm_states),
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.log_subsys = DMSC,
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.event_names = msc_t_fsm_event_names,
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.cleanup = msc_t_remote_fsm_cleanup,
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};
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static __attribute__((constructor)) void msc_t_remote_fsm_init(void)
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{
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OSMO_ASSERT(osmo_fsm_register(&msc_t_remote_fsm) == 0);
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}
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struct msc_t *msc_t_remote_alloc(struct msub *msub, struct ran_infra *ran,
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const uint8_t *remote_msc_name, size_t remote_msc_name_len)
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{
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struct msc_t *msc_t;
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msub_role_alloc(msub, MSC_ROLE_T, &msc_t_remote_fsm, struct msc_t, ran);
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msc_t = msub_msc_t(msub);
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if (!msc_t)
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return NULL;
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msc_t->c.remote_to = e_link_alloc(msub_net(msub)->gcm, msc_t->c.fi, remote_msc_name, remote_msc_name_len);
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if (!msc_t->c.remote_to) {
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LOG_MSC_T_REMOTE(msc_t, LOGL_ERROR, "Failed to set up E link over GSUP to remote MSC\n");
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msc_t_clear(msc_t);
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return NULL;
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}
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osmo_fsm_inst_state_chg(msc_t->c.fi, MSC_T_ST_WAIT_HO_COMPLETE, 0, 0);
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return msc_t;
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}
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