Neels Hofmeyr | c4628a3 | 2018-12-07 14:47:34 +0100 | [diff] [blame] | 1 | /* The MSC-A role implementation variant that forwards requests to/from a remote MSC. */ |
| 2 | /* |
Vadim Yanitskiy | 999a593 | 2023-05-18 17:22:26 +0700 | [diff] [blame] | 3 | * (C) 2019 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de> |
Neels Hofmeyr | c4628a3 | 2018-12-07 14:47:34 +0100 | [diff] [blame] | 4 | * All Rights Reserved |
| 5 | * |
| 6 | * SPDX-License-Identifier: AGPL-3.0+ |
| 7 | * |
| 8 | * Author: Neels Hofmeyr |
| 9 | * |
| 10 | * This program is free software; you can redistribute it and/or modify |
| 11 | * it under the terms of the GNU Affero General Public License as published by |
| 12 | * the Free Software Foundation; either version 3 of the License, or |
| 13 | * (at your option) any later version. |
| 14 | * |
| 15 | * This program is distributed in the hope that it will be useful, |
| 16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | * GNU Affero General Public License for more details. |
| 19 | * |
| 20 | * You should have received a copy of the GNU Affero General Public License |
| 21 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 22 | */ |
| 23 | |
| 24 | #include <inttypes.h> |
| 25 | |
| 26 | #include <osmocom/core/fsm.h> |
| 27 | #include <osmocom/gsm/gsup.h> |
| 28 | |
| 29 | #include <osmocom/msc/debug.h> |
| 30 | #include <osmocom/msc/gsm_data.h> |
| 31 | #include <osmocom/msc/msc_a_remote.h> |
| 32 | #include <osmocom/msc/msc_roles.h> |
| 33 | #include <osmocom/msc/msub.h> |
| 34 | #include <osmocom/msc/msc_a.h> |
| 35 | #include <osmocom/msc/msc_t.h> |
| 36 | #include <osmocom/msc/e_link.h> |
| 37 | #include <osmocom/msc/vlr.h> |
| 38 | #include <osmocom/msc/ran_peer.h> |
| 39 | |
| 40 | static struct osmo_fsm msc_a_remote_fsm; |
| 41 | |
| 42 | static struct msc_a *msc_a_remote_priv(struct osmo_fsm_inst *fi) |
| 43 | { |
| 44 | OSMO_ASSERT(fi); |
| 45 | OSMO_ASSERT(fi->fsm == &msc_a_remote_fsm); |
| 46 | OSMO_ASSERT(fi->priv); |
| 47 | return fi->priv; |
| 48 | } |
| 49 | |
| 50 | /* 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 |
| 51 | * directly, it forwards the events to a remote MSC-A role, via E-over-GSUP. |
| 52 | * |
| 53 | * [MSC-A---------------------] [MSC-B---------------------] |
| 54 | * msc_a <-- msc_{i,t}_remote <---GSUP---- msc_a_remote <-- msc_{i,t} <--BSSMAP--- [BSS] |
| 55 | * ^you are here |
| 56 | */ |
| 57 | static int msc_a_remote_msg_up_to_remote_msc(struct msc_a *msc_a, |
| 58 | enum msc_role from_role, |
| 59 | enum osmo_gsup_message_type message_type, |
| 60 | struct an_apdu *an_apdu) |
| 61 | { |
| 62 | struct osmo_gsup_message m; |
| 63 | struct e_link *e = msc_a->c.remote_to; |
| 64 | |
| 65 | if (!e) { |
| 66 | LOG_MSC_A_REMOTE(msc_a, LOGL_ERROR, "No E link to remote MSC, cannot send AN-APDU\n"); |
| 67 | return -1; |
| 68 | } |
| 69 | |
| 70 | if (e_prep_gsup_msg(e, &m)) { |
| 71 | LOG_MSC_A_REMOTE(msc_a, LOGL_ERROR, "Error composing E-interface GSUP message\n"); |
| 72 | return -1; |
| 73 | } |
| 74 | m.message_type = message_type; |
| 75 | if (an_apdu) { |
| 76 | if (gsup_msg_assign_an_apdu(&m, an_apdu)) { |
| 77 | LOG_MSC_A_REMOTE(msc_a, LOGL_ERROR, "Error composing E-interface GSUP message\n"); |
| 78 | return -1; |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | return e_tx(e, &m); |
| 83 | } |
| 84 | |
| 85 | /* [MSC-A-----------------] [MSC-B-----------------] |
| 86 | * msc_a --> msc_t_remote ----GSUP---> msc_a_remote --> msc_t ---BSSMAP--> [BSS] |
| 87 | * ^you are here |
| 88 | */ |
| 89 | static void msc_a_remote_rx_gsup_to_msc_t(struct msc_a *msc_a, const struct osmo_gsup_message *gsup_msg) |
| 90 | { |
| 91 | uint32_t event; |
| 92 | struct an_apdu an_apdu; |
| 93 | |
| 94 | switch (gsup_msg->message_type) { |
| 95 | case OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_REQUEST: |
| 96 | event = MSC_T_EV_FROM_A_PREPARE_HANDOVER_REQUEST; |
| 97 | break; |
| 98 | |
| 99 | case OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_REQUEST: |
| 100 | case OSMO_GSUP_MSGT_E_FORWARD_ACCESS_SIGNALLING_REQUEST: |
| 101 | event = MSC_T_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST; |
| 102 | break; |
| 103 | |
| 104 | case OSMO_GSUP_MSGT_E_CLOSE: |
| 105 | case OSMO_GSUP_MSGT_E_ABORT: |
| 106 | case OSMO_GSUP_MSGT_E_ROUTING_ERROR: |
| 107 | /* TODO: maybe some non-"normal" release with error cause? */ |
| 108 | msc_a_release_cn(msc_a); |
| 109 | return; |
| 110 | |
| 111 | default: |
| 112 | LOG_MSC_A_REMOTE(msc_a, LOGL_ERROR, "Unhandled GSUP message type: %s\n", |
| 113 | osmo_gsup_message_type_name(gsup_msg->message_type)); |
| 114 | return; |
| 115 | }; |
| 116 | |
| 117 | gsup_msg_to_an_apdu(&an_apdu, gsup_msg); |
| 118 | msub_role_dispatch(msc_a->c.msub, MSC_ROLE_T, event, &an_apdu); |
| 119 | if (an_apdu.msg) |
| 120 | msgb_free(an_apdu.msg); |
| 121 | } |
| 122 | |
| 123 | /* [MSC-A-----------------] [MSC-B-----------------] |
| 124 | * msc_a --> msc_i_remote ----GSUP---> msc_a_remote --> msc_i ---BSSMAP--> [BSS] |
| 125 | * ^you are here |
| 126 | */ |
| 127 | static void msc_a_remote_rx_gsup_to_msc_i(struct msc_a *msc_a, const struct osmo_gsup_message *gsup_msg) |
| 128 | { |
| 129 | uint32_t event; |
| 130 | struct an_apdu an_apdu; |
| 131 | |
| 132 | switch (gsup_msg->message_type) { |
| 133 | case OSMO_GSUP_MSGT_E_FORWARD_ACCESS_SIGNALLING_REQUEST: |
| 134 | event = MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST; |
| 135 | break; |
| 136 | |
| 137 | case OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_ERROR: |
| 138 | case OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_RESULT: |
| 139 | event = MSC_I_EV_FROM_A_SEND_END_SIGNAL_RESPONSE; |
| 140 | break; |
| 141 | |
| 142 | case OSMO_GSUP_MSGT_E_PREPARE_SUBSEQUENT_HANDOVER_RESULT: |
| 143 | case OSMO_GSUP_MSGT_E_PREPARE_SUBSEQUENT_HANDOVER_ERROR: |
| 144 | event = MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_RESULT; |
| 145 | break; |
| 146 | |
| 147 | case OSMO_GSUP_MSGT_E_CLOSE: |
| 148 | case OSMO_GSUP_MSGT_E_ABORT: |
| 149 | case OSMO_GSUP_MSGT_E_ROUTING_ERROR: |
| 150 | /* TODO: maybe some non-"normal" release with error cause? */ |
| 151 | msc_a_release_cn(msc_a); |
| 152 | return; |
| 153 | |
| 154 | default: |
| 155 | LOG_MSC_A_REMOTE(msc_a, LOGL_ERROR, "Unhandled GSUP message type: %s\n", |
| 156 | osmo_gsup_message_type_name(gsup_msg->message_type)); |
| 157 | return; |
| 158 | }; |
| 159 | |
| 160 | gsup_msg_to_an_apdu(&an_apdu, gsup_msg); |
| 161 | msub_role_dispatch(msc_a->c.msub, MSC_ROLE_I, event, &an_apdu); |
| 162 | if (an_apdu.msg) |
| 163 | msgb_free(an_apdu.msg); |
| 164 | } |
| 165 | |
| 166 | static void msc_a_remote_send_handover_failure(struct msc_a *msc_a, enum gsm0808_cause cause) |
| 167 | { |
| 168 | struct ran_msg ran_enc_msg = { |
| 169 | .msg_type = RAN_MSG_HANDOVER_FAILURE, |
| 170 | .handover_failure = { |
| 171 | .cause = cause, |
| 172 | }, |
| 173 | }; |
| 174 | struct an_apdu an_apdu = { |
| 175 | .an_proto = msc_a->c.ran->an_proto, |
| 176 | .msg = msc_role_ran_encode(msc_a->c.fi, &ran_enc_msg), |
| 177 | }; |
| 178 | if (!an_apdu.msg) |
| 179 | return; |
| 180 | |
| 181 | msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_T, OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_ERROR, &an_apdu); |
Neels Hofmeyr | c4628a3 | 2018-12-07 14:47:34 +0100 | [diff] [blame] | 182 | } |
| 183 | |
| 184 | /* [MSC-A---------------------] [MSC-B---------------------] |
| 185 | * msc_a --> msc_{i,t}_remote ----GSUP---> msc_a_remote --> msc_{i,t} ---BSSMAP--> [BSS] |
| 186 | * ^you are here |
| 187 | */ |
| 188 | static void msc_a_remote_rx_gsup(struct msc_a *msc_a, const struct osmo_gsup_message *gsup_msg) |
| 189 | { |
| 190 | struct msc_t *msc_t = msc_a_msc_t(msc_a); |
| 191 | struct msc_i *msc_i = msc_a_msc_i(msc_a); |
| 192 | |
| 193 | /* If starting a new Handover, this subscriber *must* be new and completely unattached. Create a new msc_t role |
| 194 | * to receive below event. */ |
| 195 | if (gsup_msg->message_type == OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_REQUEST) { |
| 196 | if (msc_t || msc_i) { |
| 197 | LOG_MSC_A_REMOTE_CAT(msc_a, DLGSUP, LOGL_ERROR, |
| 198 | "Already have an MSC-T or -I role, cannot Rx %s from remote MSC\n", |
| 199 | osmo_gsup_message_type_name(gsup_msg->message_type)); |
| 200 | msc_a_remote_send_handover_failure(msc_a, GSM0808_CAUSE_EQUIPMENT_FAILURE); |
| 201 | return; |
| 202 | } |
| 203 | |
| 204 | msc_t = msc_t_alloc_without_ran_peer(msc_a->c.msub, msc_a->c.ran); |
| 205 | } |
| 206 | |
| 207 | /* 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 |
| 208 | * messages from MSC-A *must* be intended for the MSC-T role. As soon as the Handover is successful, the MSC-T |
| 209 | * role disappears and an MSC-I role appears. */ |
| 210 | if (msc_t) { |
| 211 | LOG_MSC_A_REMOTE_CAT(msc_a, DLGSUP, LOGL_DEBUG, "Routing to MSC-T: %s\n", |
| 212 | osmo_gsup_message_type_name(gsup_msg->message_type)); |
| 213 | msc_a_remote_rx_gsup_to_msc_t(msc_a, gsup_msg); |
| 214 | } else if (msc_i) { |
| 215 | LOG_MSC_A_REMOTE_CAT(msc_a, DLGSUP, LOGL_DEBUG, "Routing to MSC-I: %s\n", |
| 216 | osmo_gsup_message_type_name(gsup_msg->message_type)); |
| 217 | msc_a_remote_rx_gsup_to_msc_i(msc_a, gsup_msg); |
| 218 | } else { |
| 219 | LOG_MSC_A_REMOTE_CAT(msc_a, DLGSUP, LOGL_ERROR, |
| 220 | "No MSC-T nor MSC-I role present, cannot Rx GSUP %s\n", |
| 221 | osmo_gsup_message_type_name(gsup_msg->message_type)); |
| 222 | } |
| 223 | } |
| 224 | |
| 225 | static void msc_a_remote_fsm_communicating(struct osmo_fsm_inst *fi, uint32_t event, void *data) |
| 226 | { |
| 227 | struct msc_a *msc_a = msc_a_remote_priv(fi); |
| 228 | struct an_apdu *an_apdu; |
| 229 | |
| 230 | switch (event) { |
| 231 | |
| 232 | case MSC_REMOTE_EV_RX_GSUP: |
| 233 | /* [MSC-A---------------------] [MSC-B---------------------] |
| 234 | * msc_a --> msc_{i,t}_remote ----GSUP---> msc_a_remote --> msc_{i,t} ---BSSMAP--> [BSS] |
| 235 | * ^you are here |
| 236 | */ |
| 237 | msc_a_remote_rx_gsup(msc_a, (const struct osmo_gsup_message*)data); |
| 238 | return; |
| 239 | |
| 240 | /* For all remaining cases: |
| 241 | * [MSC-A---------------------] [MSC-B---------------------] |
| 242 | * msc_a <-- msc_{i,t}_remote <---GSUP---- msc_a_remote <-- msc_{i,t} <--BSSMAP--- [BSS] |
| 243 | * you are here^ |
| 244 | */ |
| 245 | |
| 246 | case MSC_A_EV_FROM_I_PROCESS_ACCESS_SIGNALLING_REQUEST: |
| 247 | an_apdu = data; |
| 248 | msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_I, |
| 249 | OSMO_GSUP_MSGT_E_PROCESS_ACCESS_SIGNALLING_REQUEST, an_apdu); |
| 250 | return; |
| 251 | |
| 252 | case MSC_A_EV_FROM_I_PREPARE_SUBSEQUENT_HANDOVER_REQUEST: |
| 253 | an_apdu = data; |
| 254 | msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_I, |
| 255 | OSMO_GSUP_MSGT_E_PREPARE_SUBSEQUENT_HANDOVER_REQUEST, an_apdu); |
| 256 | return; |
| 257 | |
| 258 | case MSC_A_EV_FROM_I_SEND_END_SIGNAL_REQUEST: |
| 259 | an_apdu = data; |
| 260 | msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_I, |
| 261 | OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_REQUEST, an_apdu); |
| 262 | return; |
| 263 | |
| 264 | case MSC_A_EV_FROM_T_PREPARE_HANDOVER_RESPONSE: |
| 265 | an_apdu = data; |
| 266 | msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_T, |
| 267 | OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_RESULT, an_apdu); |
| 268 | return; |
| 269 | |
| 270 | case MSC_A_EV_FROM_T_PREPARE_HANDOVER_FAILURE: |
| 271 | an_apdu = data; |
| 272 | msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_T, |
| 273 | OSMO_GSUP_MSGT_E_PREPARE_HANDOVER_ERROR, an_apdu); |
| 274 | return; |
| 275 | |
| 276 | case MSC_A_EV_FROM_T_PROCESS_ACCESS_SIGNALLING_REQUEST: |
| 277 | an_apdu = data; |
| 278 | msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_T, |
| 279 | OSMO_GSUP_MSGT_E_PROCESS_ACCESS_SIGNALLING_REQUEST, an_apdu); |
| 280 | return; |
| 281 | |
| 282 | case MSC_A_EV_FROM_T_SEND_END_SIGNAL_REQUEST: |
| 283 | an_apdu = data; |
| 284 | msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_T, |
| 285 | OSMO_GSUP_MSGT_E_SEND_END_SIGNAL_REQUEST, an_apdu); |
| 286 | return; |
| 287 | |
| 288 | case MSC_A_EV_CN_CLOSE: |
| 289 | case MSC_A_EV_MO_CLOSE: |
| 290 | osmo_fsm_inst_state_chg(msc_a->c.fi, MSC_A_ST_RELEASING, 0, 0); |
| 291 | return; |
| 292 | |
| 293 | default: |
| 294 | OSMO_ASSERT(false); |
| 295 | } |
| 296 | } |
| 297 | |
| 298 | static void msc_a_remote_fsm_releasing_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state) |
| 299 | { |
| 300 | osmo_fsm_inst_term(fi, OSMO_FSM_TERM_REGULAR, fi); |
| 301 | } |
| 302 | |
| 303 | static void msc_a_remote_fsm_cleanup(struct osmo_fsm_inst *fi, enum osmo_fsm_term_cause cause) |
| 304 | { |
| 305 | struct msc_a *msc_a = msc_a_remote_priv(fi); |
| 306 | if (msc_a->c.msub->role[MSC_ROLE_I]) |
| 307 | msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_I, OSMO_GSUP_MSGT_E_CLOSE, NULL); |
| 308 | if (msc_a->c.msub->role[MSC_ROLE_T]) |
| 309 | msc_a_remote_msg_up_to_remote_msc(msc_a, MSC_ROLE_T, OSMO_GSUP_MSGT_E_CLOSE, NULL); |
| 310 | } |
| 311 | |
| 312 | #define S(x) (1 << (x)) |
| 313 | |
| 314 | /* FSM events are by definition compatible with msc_a_fsm. States could be a separate enum, but so that |
| 315 | * msc_a_is_accepted() also works on remote msc_a, this FSM shares state numbers with the msc_a_fsm_states. */ |
| 316 | static const struct osmo_fsm_state msc_a_remote_fsm_states[] = { |
| 317 | /* Whichever MSC_A_ST would be the first for the real MSC-A implementation, a fresh FSM instance will start in |
| 318 | * state == 0 and we just need to be able to transition out of it. */ |
| 319 | [0] = { |
| 320 | .name = "INIT-REMOTE", |
| 321 | .out_state_mask = 0 |
| 322 | | S(MSC_A_ST_COMMUNICATING) |
| 323 | | S(MSC_A_ST_RELEASING) |
| 324 | , |
| 325 | }, |
| 326 | [MSC_A_ST_COMMUNICATING] = { |
| 327 | .name = "COMMUNICATING", |
| 328 | .action = msc_a_remote_fsm_communicating, |
| 329 | .in_event_mask = 0 |
| 330 | | S(MSC_REMOTE_EV_RX_GSUP) |
| 331 | | S(MSC_A_EV_FROM_I_PROCESS_ACCESS_SIGNALLING_REQUEST) |
| 332 | | S(MSC_A_EV_FROM_I_PREPARE_SUBSEQUENT_HANDOVER_REQUEST) |
| 333 | | S(MSC_A_EV_FROM_I_SEND_END_SIGNAL_REQUEST) |
| 334 | | S(MSC_A_EV_FROM_T_PREPARE_HANDOVER_RESPONSE) |
| 335 | | S(MSC_A_EV_FROM_T_PREPARE_HANDOVER_FAILURE) |
| 336 | | S(MSC_A_EV_FROM_T_PROCESS_ACCESS_SIGNALLING_REQUEST) |
| 337 | | S(MSC_A_EV_FROM_T_SEND_END_SIGNAL_REQUEST) |
| 338 | | S(MSC_A_EV_CN_CLOSE) |
| 339 | | S(MSC_A_EV_MO_CLOSE) |
| 340 | , |
| 341 | .out_state_mask = 0 |
| 342 | | S(MSC_A_ST_RELEASING) |
| 343 | , |
| 344 | }, |
| 345 | [MSC_A_ST_RELEASING] = { |
| 346 | .name = "RELEASING", |
| 347 | .onenter = msc_a_remote_fsm_releasing_onenter, |
| 348 | }, |
| 349 | }; |
| 350 | |
| 351 | static struct osmo_fsm msc_a_remote_fsm = { |
| 352 | .name = "msc_a_remote", |
| 353 | .states = msc_a_remote_fsm_states, |
| 354 | .num_states = ARRAY_SIZE(msc_a_remote_fsm_states), |
| 355 | .log_subsys = DMSC, |
| 356 | .event_names = msc_a_fsm_event_names, |
| 357 | .cleanup = msc_a_remote_fsm_cleanup, |
| 358 | }; |
| 359 | |
| 360 | static __attribute__((constructor)) void msc_a_remote_fsm_init(void) |
| 361 | { |
| 362 | OSMO_ASSERT(osmo_fsm_register(&msc_a_remote_fsm) == 0); |
| 363 | } |
| 364 | |
| 365 | struct msc_a *msc_a_remote_alloc(struct msub *msub, struct ran_infra *ran, |
| 366 | const uint8_t *remote_msc_name, size_t remote_msc_name_len) |
| 367 | { |
| 368 | struct msc_a *msc_a; |
| 369 | |
| 370 | msub_role_alloc(msub, MSC_ROLE_A, &msc_a_remote_fsm, struct msc_a, ran); |
| 371 | msc_a = msub_msc_a(msub); |
| 372 | if (!msc_a) { |
| 373 | LOG_MSUB(msub, LOGL_ERROR, "Error setting up MSC-A remote role\n"); |
| 374 | return NULL; |
| 375 | } |
| 376 | |
| 377 | msc_a->c.remote_to = e_link_alloc(msub_net(msub)->gcm, msc_a->c.fi, remote_msc_name, remote_msc_name_len); |
| 378 | if (!msc_a->c.remote_to) { |
| 379 | LOG_MSC_A_REMOTE(msc_a, LOGL_ERROR, "Failed to set up E link\n"); |
| 380 | msc_a_release_cn(msc_a); |
| 381 | return NULL; |
| 382 | } |
| 383 | |
| 384 | msc_a_update_id(msc_a); |
| 385 | |
| 386 | /* Immediately get out of state 0. */ |
| 387 | osmo_fsm_inst_state_chg(msc_a->c.fi, MSC_A_ST_COMMUNICATING, 0, 0); |
| 388 | |
| 389 | return msc_a; |
| 390 | } |