diff options
Diffstat (limited to 'src/libmsc/msc_a_remote.c')
| -rw-r--r-- | src/libmsc/msc_a_remote.c | 392 |
1 files changed, 392 insertions, 0 deletions
diff --git a/src/libmsc/msc_a_remote.c b/src/libmsc/msc_a_remote.c new file mode 100644 index 000000000..ce07e4a5f --- /dev/null +++ b/src/libmsc/msc_a_remote.c @@ -0,0 +1,392 @@ +/* The MSC-A 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 <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, from_role, &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); + msgb_free(an_apdu.msg); + return; +} + +/* [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; +} |