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