889 lines
30 KiB
C
889 lines
30 KiB
C
/* MSC Handover implementation */
|
|
/*
|
|
* (C) 2019 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de>
|
|
* All Rights Reserved
|
|
*
|
|
* Author: Neels Hofmeyr
|
|
*
|
|
* SPDX-License-Identifier: GPL-2.0+
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 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 General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License along
|
|
* with this program; if not, write to the Free Software Foundation, Inc.,
|
|
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
*/
|
|
|
|
#include <osmocom/core/fsm.h>
|
|
#include <osmocom/gsm/protocol/gsm_08_08.h>
|
|
#include <osmocom/sigtran/sccp_helpers.h>
|
|
|
|
#include <osmocom/msc/msc_ho.h>
|
|
#include <osmocom/msc/ran_msg.h>
|
|
#include <osmocom/msc/msc_a.h>
|
|
#include <osmocom/msc/msc_i.h>
|
|
#include <osmocom/msc/msc_t.h>
|
|
#include <osmocom/msc/e_link.h>
|
|
#include <osmocom/msc/msc_i_remote.h>
|
|
#include <osmocom/msc/msc_t_remote.h>
|
|
#include <osmocom/msc/neighbor_ident.h>
|
|
#include <osmocom/msc/gsm_data.h>
|
|
#include <osmocom/msc/ran_peer.h>
|
|
#include <osmocom/msc/vlr.h>
|
|
#include <osmocom/msc/transaction.h>
|
|
#include <osmocom/msc/gsm_04_08.h>
|
|
#include <osmocom/msc/call_leg.h>
|
|
#include <osmocom/msc/rtp_stream.h>
|
|
#include <osmocom/msc/mncc_call.h>
|
|
|
|
struct osmo_fsm msc_ho_fsm;
|
|
|
|
#define MSC_A_USE_HANDOVER "Handover"
|
|
|
|
static const struct osmo_tdef_state_timeout msc_ho_fsm_timeouts[32] = {
|
|
[MSC_HO_ST_REQUIRED] = { .keep_timer = true, .T = -3 },
|
|
[MSC_HO_ST_WAIT_REQUEST_ACK] = { .keep_timer = true },
|
|
[MSC_HO_ST_WAIT_COMPLETE] = { .T = -3 },
|
|
};
|
|
|
|
/* Transition to a state, using the T timer defined in msc_a_fsm_timeouts.
|
|
* The actual timeout value is in turn obtained from network->T_defs.
|
|
* Assumes local variable fi exists. */
|
|
#define msc_ho_fsm_state_chg(msc_a, state) \
|
|
osmo_tdef_fsm_inst_state_chg((msc_a)->ho.fi, state, msc_ho_fsm_timeouts, (msc_a)->c.ran->tdefs, 5)
|
|
|
|
static __attribute__((constructor)) void msc_ho_fsm_init()
|
|
{
|
|
OSMO_ASSERT(osmo_fsm_register(&msc_ho_fsm) == 0);
|
|
}
|
|
|
|
void msc_ho_down_required_reject(struct msc_a *msc_a, enum gsm0808_cause cause)
|
|
{
|
|
struct msc_i *msc_i;
|
|
uint32_t event;
|
|
|
|
msc_i = msc_a_msc_i(msc_a);
|
|
OSMO_ASSERT(msc_i);
|
|
|
|
struct ran_msg ran_enc_msg = {
|
|
.msg_type = RAN_MSG_HANDOVER_REQUIRED_REJECT,
|
|
.handover_required_reject = {
|
|
.cause = cause,
|
|
},
|
|
};
|
|
|
|
if (msc_i->c.remote_to)
|
|
event = MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_ERROR;
|
|
else
|
|
event = MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST;
|
|
|
|
msc_a_msg_down(msc_a, MSC_ROLE_I, event, &ran_enc_msg);
|
|
}
|
|
|
|
/* Even though this is using the 3GPP TS 48.008 definitions and naming, the intention is to be RAN implementation agnostic.
|
|
* For other RAN types, the 48.008 items shall be translated to their respective counterparts. */
|
|
void msc_ho_start(struct msc_a *msc_a, const struct ran_handover_required *ho_req)
|
|
{
|
|
if (msc_a->ho.fi) {
|
|
LOG_HO(msc_a, LOGL_ERROR, "Rx Handover Required, but Handover is still ongoing\n");
|
|
msc_ho_down_required_reject(msc_a, GSM0808_CAUSE_PROTOCOL_ERROR_BETWEEN_BSS_AND_MSC);
|
|
return;
|
|
}
|
|
|
|
if (!ho_req->cil.id_list_len) {
|
|
LOG_HO(msc_a, LOGL_ERROR, "Rx Handover Required without a Cell Identifier List\n");
|
|
msc_ho_down_required_reject(msc_a, GSM0808_CAUSE_INFORMATION_ELEMENT_OR_FIELD_MISSING);
|
|
return;
|
|
}
|
|
|
|
if (msc_a_msc_t(msc_a)) {
|
|
LOG_HO(msc_a, LOGL_ERROR,
|
|
"Rx Handover Required, but this subscriber still has an active MSC-T role: %s\n",
|
|
msc_a_msc_t(msc_a)->c.fi->id);
|
|
/* Protocol error because the BSS is not supposed to send another Handover Required before the previous
|
|
* attempt has concluded. */
|
|
msc_ho_down_required_reject(msc_a, GSM0808_CAUSE_PROTOCOL_ERROR_BETWEEN_BSS_AND_MSC);
|
|
return;
|
|
}
|
|
|
|
/* Paranoia: make sure we start with clean state */
|
|
msc_a->ho = (struct msc_ho_state){};
|
|
|
|
msc_a->ho.fi = osmo_fsm_inst_alloc_child(&msc_ho_fsm, msc_a->c.fi, MSC_A_EV_HANDOVER_END);
|
|
OSMO_ASSERT(msc_a->ho.fi);
|
|
|
|
msc_a->ho.fi->priv = msc_a;
|
|
msc_a->ho.info = *ho_req;
|
|
msc_a->ho.next_cil_idx = 0;
|
|
|
|
/* Start the timeout */
|
|
msc_ho_fsm_state_chg(msc_a, MSC_HO_ST_REQUIRED);
|
|
}
|
|
|
|
static void msc_ho_rtp_rollback_to_old_cell(struct msc_a *msc_a);
|
|
|
|
static void msc_ho_end(struct msc_a *msc_a, bool success, enum gsm0808_cause cause)
|
|
{
|
|
struct msc_i *msc_i;
|
|
struct msc_t *msc_t = msc_a_msc_t(msc_a);
|
|
|
|
if (!success) {
|
|
msc_ho_rtp_rollback_to_old_cell(msc_a);
|
|
msc_ho_down_required_reject(msc_a, cause);
|
|
}
|
|
|
|
if (success) {
|
|
/* Any previous call forwarding to a remote MSC becomes obsolete. */
|
|
if (msc_a->cc.mncc_forwarding_to_remote_ran) {
|
|
mncc_call_release(msc_a->cc.mncc_forwarding_to_remote_ran);
|
|
msc_a->cc.mncc_forwarding_to_remote_ran = NULL;
|
|
}
|
|
|
|
/* Replace MSC-I with new MSC-T */
|
|
if (msc_t->c.remote_to) {
|
|
/* Inter-MSC Handover. */
|
|
|
|
/* The MNCC forwarding set up for inter-MSC handover, so far transitional in msc_a->ho now
|
|
* becomes the "officially" active MNCC forwarding for this call. */
|
|
msc_a->cc.mncc_forwarding_to_remote_ran = msc_a->ho.new_cell.mncc_forwarding_to_remote_ran;
|
|
msc_a->ho.new_cell.mncc_forwarding_to_remote_ran = NULL;
|
|
mncc_call_reparent(msc_a->cc.mncc_forwarding_to_remote_ran,
|
|
msc_a->c.fi, -1, MSC_MNCC_EV_CALL_ENDED, NULL, NULL);
|
|
|
|
/* inter-MSC link. msc_i_remote_alloc() properly "steals" the e_link from msc_t. */
|
|
msc_i = msc_i_remote_alloc(msc_a->c.msub, msc_t->c.ran, msc_t->c.remote_to);
|
|
OSMO_ASSERT(msc_t->c.remote_to == NULL);
|
|
} else {
|
|
/* local BSS */
|
|
msc_i = msc_i_alloc(msc_a->c.msub, msc_t->c.ran);
|
|
/* msc_i_set_ran_conn() properly "steals" the ran_conn from msc_t */
|
|
msc_i_set_ran_conn(msc_i, msc_t->ran_conn);
|
|
}
|
|
}
|
|
|
|
osmo_fsm_inst_term(msc_a->ho.fi, OSMO_FSM_TERM_REGULAR, NULL);
|
|
}
|
|
|
|
#define msc_ho_failed(msc_a, cause, fmt, args...) do { \
|
|
LOG_HO(msc_a, LOGL_ERROR, fmt, ##args); \
|
|
msc_ho_end(msc_a, false, cause); \
|
|
} while(0)
|
|
#define msc_ho_try_next_cell(msc_a, fmt, args...) do {\
|
|
LOG_HO(msc_a, LOGL_ERROR, fmt, ##args); \
|
|
msc_ho_fsm_state_chg(msc_a, MSC_HO_ST_REQUIRED); \
|
|
} while(0)
|
|
#define msc_ho_success(msc_a) msc_ho_end(msc_a, true, 0)
|
|
|
|
enum msc_neighbor_type msc_ho_find_target_cell(struct msc_a *msc_a, const struct gsm0808_cell_id *cid,
|
|
const struct neighbor_ident_entry **remote_msc,
|
|
struct ran_peer **ran_peer_from_neighbor_ident,
|
|
struct ran_peer **ran_peer_from_seen_cells)
|
|
{
|
|
struct gsm_network *net = msc_a_net(msc_a);
|
|
const struct neighbor_ident_entry *e;
|
|
struct sccp_ran_inst *sri;
|
|
struct ran_peer *rp_from_neighbor_ident = NULL;
|
|
struct ran_peer *rp_from_cell_id = NULL;
|
|
struct ran_peer *rp;
|
|
int i;
|
|
|
|
OSMO_ASSERT(remote_msc);
|
|
OSMO_ASSERT(ran_peer_from_neighbor_ident);
|
|
OSMO_ASSERT(ran_peer_from_seen_cells);
|
|
|
|
e = neighbor_ident_find_by_cell(&net->neighbor_ident_list, msc_a->c.ran->type, cid);
|
|
|
|
if (e && e->addr.type == MSC_NEIGHBOR_TYPE_REMOTE_MSC) {
|
|
*remote_msc = e;
|
|
return MSC_NEIGHBOR_TYPE_REMOTE_MSC;
|
|
}
|
|
|
|
/* It is not a remote MSC target. Figure out local RAN peers. */
|
|
|
|
if (e && e->addr.type == MSC_NEIGHBOR_TYPE_LOCAL_RAN_PEER) {
|
|
/* Find local RAN peer in neighbor config. If anything is wrong with that, just keep
|
|
* rp_from_neighbor_ident == NULL. */
|
|
|
|
struct sccp_ran_inst *sri_from_neighbor_ident = NULL;
|
|
struct osmo_ss7_instance *ss7 = NULL;
|
|
|
|
/* Get the sccp_ran_inst with sanity checkin. If anything is fishy, just keep
|
|
* sri_from_neighbor_ident == NULL and below code will notice the error. */
|
|
if (e->addr.ran_type < msc_ran_infra_len) {
|
|
sri_from_neighbor_ident = msc_ran_infra[e->addr.ran_type].sri;
|
|
ss7 = osmo_sccp_get_ss7(sri_from_neighbor_ident->sccp);
|
|
if (!ss7)
|
|
sri_from_neighbor_ident = NULL;
|
|
}
|
|
|
|
if (!sri_from_neighbor_ident) {
|
|
LOG_HO(msc_a, LOGL_ERROR, "Cannot handover to RAN type %s\n", osmo_rat_type_name(e->addr.ran_type));
|
|
} else {
|
|
/* Interpret the point-code string placed in the neighbors config. */
|
|
int pc = osmo_ss7_pointcode_parse(ss7, e->addr.local_ran_peer_pc_str);
|
|
|
|
if (pc < 0) {
|
|
LOG_HO(msc_a, LOGL_ERROR, "Invalid point code string: %s\n",
|
|
osmo_quote_str(e->addr.local_ran_peer_pc_str, -1));
|
|
} else {
|
|
struct osmo_sccp_addr addr = {};
|
|
osmo_sccp_make_addr_pc_ssn(&addr, pc, sri_from_neighbor_ident->ran->ssn);
|
|
rp_from_neighbor_ident = ran_peer_find_by_addr(sri_from_neighbor_ident, &addr);
|
|
}
|
|
}
|
|
|
|
if (!rp_from_neighbor_ident) {
|
|
LOG_HO(msc_a, LOGL_ERROR, "Target RAN peer from neighbor config is not connected:"
|
|
" Cell ID %s resolves to target address %s\n",
|
|
gsm0808_cell_id_name(cid), e->addr.local_ran_peer_pc_str);
|
|
} else if (rp_from_neighbor_ident->fi->state != RAN_PEER_ST_READY) {
|
|
LOG_HO(msc_a, LOGL_ERROR, "Target RAN peer in invalid state: %s (%s)\n",
|
|
osmo_fsm_inst_state_name(rp_from_neighbor_ident->fi),
|
|
rp_from_neighbor_ident->fi->id);
|
|
rp_from_neighbor_ident = NULL;
|
|
}
|
|
}
|
|
|
|
/* Figure out actually connected RAN peers for this cell ID.
|
|
* If no cell has been found yet at all, this might determine a Handover target,
|
|
* otherwise this is for sanity checking. If none is found, just keep rp_from_cell_id == NULL. */
|
|
|
|
/* Iterate all connected RAN peers. Possibly, more than one RAN peer has advertised a match for this Cell ID.
|
|
* For example, if the handover target is identified as LAC=23 but there are multiple cells with distinct CIs
|
|
* serving in LAC=23, we have an ambiguity. It's up to the user to configure correctly, help with logging. */
|
|
for (i = 0; i < msc_ran_infra_len; i++) {
|
|
sri = msc_ran_infra[i].sri;
|
|
if (!sri)
|
|
continue;
|
|
|
|
rp = ran_peer_find_by_cell_id(sri, cid, true);
|
|
if (rp && rp->fi && rp->fi->state == RAN_PEER_ST_READY) {
|
|
if (rp_from_cell_id) {
|
|
LOG_HO(msc_a, LOGL_ERROR,
|
|
"Ambiguous match for cell ID %s: more than one RAN type is serving this cell"
|
|
" ID: %s and %s\n",
|
|
gsm0808_cell_id_name(cid),
|
|
rp_from_cell_id->fi->id,
|
|
rp->fi->id);
|
|
/* But logging is all we're going to do about it. */
|
|
}
|
|
|
|
/* Use the first found RAN peer, but if multiple matches are found, favor the one that matches
|
|
* the current RAN type. */
|
|
if (!rp_from_cell_id || rp->sri == msc_a->c.ran->sri)
|
|
rp_from_cell_id = rp;
|
|
}
|
|
}
|
|
|
|
/* Did we find mismatching targets from neighbor config and from connected cells? */
|
|
if (rp_from_neighbor_ident && rp_from_cell_id
|
|
&& rp_from_neighbor_ident != rp_from_cell_id) {
|
|
LOG_HO(msc_a, LOGL_ERROR, "Ambiguous match for cell ID %s:"
|
|
" neighbor config points at %s; a matching cell is also served by connected RAN peer %s\n",
|
|
gsm0808_cell_id_name(cid), rp_from_neighbor_ident->fi->id, rp_from_cell_id->fi->id);
|
|
/* But logging is all we're going to do about it. */
|
|
}
|
|
|
|
if (rp_from_neighbor_ident && rp_from_neighbor_ident->sri != msc_a->c.ran->sri) {
|
|
LOG_HO(msc_a, LOGL_ERROR,
|
|
"Neighbor config indicates inter-RAT Handover, which is not implemented. Ignoring target %s\n",
|
|
rp_from_neighbor_ident->fi->id);
|
|
rp_from_neighbor_ident = NULL;
|
|
}
|
|
|
|
if (rp_from_cell_id && rp_from_cell_id->sri != msc_a->c.ran->sri) {
|
|
LOG_HO(msc_a, LOGL_ERROR,
|
|
"Target RAN peer indicates inter-RAT Handover, which is not implemented. Ignoring target %s\n",
|
|
rp_from_cell_id->fi->id);
|
|
rp_from_cell_id = NULL;
|
|
}
|
|
|
|
*ran_peer_from_neighbor_ident = rp_from_neighbor_ident;
|
|
*ran_peer_from_seen_cells = rp_from_cell_id;
|
|
|
|
return rp_from_neighbor_ident || rp_from_cell_id ? MSC_NEIGHBOR_TYPE_LOCAL_RAN_PEER : MSC_NEIGHBOR_TYPE_NONE;
|
|
}
|
|
|
|
static bool msc_ho_find_next_target_cell(struct msc_a *msc_a)
|
|
{
|
|
struct vlr_subscr *vsub = msc_a_vsub(msc_a);
|
|
struct ran_handover_required *info = &msc_a->ho.info;
|
|
struct gsm0808_cell_id *cid = &msc_a->ho.new_cell.cid;
|
|
const struct neighbor_ident_entry *e;
|
|
struct ran_peer *rp_from_neighbor_ident = NULL;
|
|
struct ran_peer *rp_from_cell_id = NULL;
|
|
struct ran_peer *rp;
|
|
|
|
unsigned int cil_idx = msc_a->ho.next_cil_idx;
|
|
msc_a->ho.next_cil_idx++;
|
|
|
|
msc_a->ho.new_cell.type = MSC_NEIGHBOR_TYPE_NONE;
|
|
|
|
if (cil_idx >= info->cil.id_list_len)
|
|
return false;
|
|
|
|
*cid = (struct gsm0808_cell_id){
|
|
.id_discr = info->cil.id_discr,
|
|
.id = info->cil.id_list[cil_idx],
|
|
};
|
|
|
|
msc_a->ho.new_cell.cgi = (struct osmo_cell_global_id){
|
|
.lai = vsub->cgi.lai,
|
|
};
|
|
gsm0808_cell_id_to_cgi(&msc_a->ho.new_cell.cgi, cid);
|
|
|
|
switch (msc_ho_find_target_cell(msc_a, cid, &e, &rp_from_neighbor_ident, &rp_from_cell_id)) {
|
|
case MSC_NEIGHBOR_TYPE_REMOTE_MSC:
|
|
OSMO_ASSERT(e);
|
|
msc_a->ho.new_cell.ran_type = e->addr.ran_type;
|
|
msc_a->ho.new_cell.type = MSC_NEIGHBOR_TYPE_REMOTE_MSC;
|
|
msc_a->ho.new_cell.msc_ipa_name = e->addr.remote_msc_ipa_name.buf;
|
|
return true;
|
|
|
|
case MSC_NEIGHBOR_TYPE_LOCAL_RAN_PEER:
|
|
rp = rp_from_neighbor_ident ? : rp_from_cell_id;
|
|
OSMO_ASSERT(rp);
|
|
msc_a->ho.new_cell.type = MSC_NEIGHBOR_TYPE_LOCAL_RAN_PEER;
|
|
msc_a->ho.new_cell.ran_peer = rp;
|
|
return true;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
|
|
LOG_HO(msc_a, LOGL_DEBUG, "Cannot find target peer for cell ID %s\n", gsm0808_cell_id_name(cid));
|
|
/* Try the next cell id, if any. */
|
|
return msc_ho_find_next_target_cell(msc_a);
|
|
}
|
|
|
|
static void msc_ho_fsm_required_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
|
|
{
|
|
struct msc_a *msc_a = fi->priv;
|
|
|
|
if (!msc_ho_find_next_target_cell(msc_a)) {
|
|
int tried = msc_a->ho.next_cil_idx - 1;
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_NO_RADIO_RESOURCE_AVAILABLE,
|
|
"Attempted Handover to %u cells without success\n", tried);
|
|
return;
|
|
}
|
|
|
|
msc_ho_fsm_state_chg(msc_a, MSC_HO_ST_WAIT_REQUEST_ACK);
|
|
}
|
|
|
|
static void msc_ho_send_handover_request(struct msc_a *msc_a)
|
|
{
|
|
struct vlr_subscr *vsub = msc_a_vsub(msc_a);
|
|
struct gsm_network *net = msc_a_net(msc_a);
|
|
struct gsm0808_channel_type channel_type;
|
|
struct ran_msg ran_enc_msg = {
|
|
.msg_type = RAN_MSG_HANDOVER_REQUEST,
|
|
.handover_request = {
|
|
.imsi = vsub->imsi,
|
|
.classmark = &vsub->classmark,
|
|
.geran = {
|
|
.chosen_encryption = &msc_a->geran_encr,
|
|
.a5_encryption_mask = net->a5_encryption_mask,
|
|
},
|
|
.bssap_cause = GSM0808_CAUSE_BETTER_CELL,
|
|
.current_channel_type_1_present = msc_a->ho.info.current_channel_type_1_present,
|
|
.current_channel_type_1 = msc_a->ho.info.current_channel_type_1,
|
|
.speech_version_used = msc_a->ho.info.speech_version_used,
|
|
.old_bss_to_new_bss_info_raw = msc_a->ho.info.old_bss_to_new_bss_info_raw,
|
|
.old_bss_to_new_bss_info_raw_len = msc_a->ho.info.old_bss_to_new_bss_info_raw_len,
|
|
|
|
/* Don't send AoIP Transport Layer Address for inter-MSC Handover */
|
|
.rtp_ran_local = (msc_a->ho.new_cell.type == MSC_NEIGHBOR_TYPE_LOCAL_RAN_PEER)
|
|
? call_leg_local_ip(msc_a->cc.call_leg, RTP_TO_RAN) : NULL,
|
|
},
|
|
};
|
|
|
|
if (msc_a->cc.active_trans) {
|
|
if (mncc_bearer_cap_to_channel_type(&channel_type, &msc_a->cc.active_trans->bearer_cap)) {
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_EQUIPMENT_FAILURE,
|
|
"Failed to encode Bearer Cap to Channel Type\n");
|
|
return;
|
|
}
|
|
ran_enc_msg.handover_request.geran.channel_type = &channel_type;
|
|
}
|
|
|
|
gsm0808_cell_id_from_cgi(&ran_enc_msg.handover_request.cell_id_serving, CELL_IDENT_WHOLE_GLOBAL, &vsub->cgi);
|
|
ran_enc_msg.handover_request.cell_id_target = msc_a->ho.new_cell.cid;
|
|
|
|
if (msc_a_msg_down(msc_a, MSC_ROLE_T, MSC_T_EV_FROM_A_PREPARE_HANDOVER_REQUEST, &ran_enc_msg))
|
|
msc_ho_try_next_cell(msc_a, "Failed to send Handover Request message\n");
|
|
}
|
|
|
|
static void msc_ho_fsm_wait_request_ack_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
|
|
{
|
|
struct msc_a *msc_a = fi->priv;
|
|
struct msc_i *msc_i = msc_a_msc_i(msc_a);
|
|
struct msc_t *msc_t;
|
|
struct ran_peer *rp;
|
|
const char *ipa_name;
|
|
|
|
msc_t = msc_a_msc_t(msc_a);
|
|
if (msc_t) {
|
|
/* All the other code should prevent this from happening, ever. */
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_EQUIPMENT_FAILURE,
|
|
"Cannot initiate Handover Request, there still is an active MSC-T role: %s\n",
|
|
msc_t->c.fi->id);
|
|
return;
|
|
}
|
|
|
|
if (!msc_i) {
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_EQUIPMENT_FAILURE,
|
|
"Cannot initiate Handover Request, there is no MSC-I role\n");
|
|
return;
|
|
}
|
|
|
|
if (!msc_i->c.remote_to
|
|
&& !(msc_i->ran_conn && msc_i->ran_conn->ran_peer)) {
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_EQUIPMENT_FAILURE,
|
|
"Cannot initiate Handover Request, MSC-I role has no connection\n");
|
|
return;
|
|
}
|
|
|
|
switch (msc_a->ho.new_cell.type) {
|
|
case MSC_NEIGHBOR_TYPE_LOCAL_RAN_PEER:
|
|
rp = msc_a->ho.new_cell.ran_peer;
|
|
OSMO_ASSERT(rp && rp->fi);
|
|
|
|
if (msc_i->c.remote_to) {
|
|
LOG_HO(msc_a, LOGL_INFO,
|
|
"Starting inter-MSC Subsequent Handover from remote MSC %s to local %s\n",
|
|
msc_i->c.remote_to->remote_name, rp->fi->id);
|
|
msc_a->ho.subsequent_ho = true;
|
|
} else {
|
|
LOG_HO(msc_a, LOGL_INFO, "Starting inter-BSC Handover from %s to %s\n",
|
|
msc_i->ran_conn->ran_peer->fi->id, rp->fi->id);
|
|
}
|
|
|
|
msc_t = msc_t_alloc(msc_a->c.msub, rp);
|
|
break;
|
|
|
|
case MSC_NEIGHBOR_TYPE_REMOTE_MSC:
|
|
ipa_name = msc_a->ho.new_cell.msc_ipa_name;
|
|
OSMO_ASSERT(ipa_name);
|
|
|
|
if (msc_i->c.remote_to) {
|
|
LOG_HO(msc_a, LOGL_INFO,
|
|
"Starting inter-MSC Subsequent Handover from remote MSC %s to remote MSC at %s\n",
|
|
msc_i->c.remote_to->remote_name, osmo_quote_str(ipa_name, -1));
|
|
msc_a->ho.subsequent_ho = true;
|
|
} else {
|
|
LOG_HO(msc_a, LOGL_INFO, "Starting inter-MSC Handover from local %s to remote MSC at %s\n",
|
|
msc_i->ran_conn->ran_peer->fi->id,
|
|
osmo_quote_str(ipa_name, -1));
|
|
}
|
|
|
|
msc_t = msc_t_remote_alloc(msc_a->c.msub, msc_a->c.ran,
|
|
(const uint8_t *) ipa_name,
|
|
strlen(ipa_name));
|
|
break;
|
|
|
|
default:
|
|
msc_ho_try_next_cell(msc_a, "unknown Handover target type %d\n", msc_a->ho.new_cell.type);
|
|
return;
|
|
}
|
|
|
|
if (!msc_t) {
|
|
/* There should definitely be one now. */
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_EQUIPMENT_FAILURE,
|
|
"Cannot initiate Handover Request, failed to set up a target MSC-T\n");
|
|
return;
|
|
}
|
|
|
|
msc_ho_send_handover_request(msc_a);
|
|
}
|
|
|
|
static void msc_ho_rx_request_ack(struct msc_a *msc_a, struct msc_a_ran_dec_data *hra);
|
|
|
|
static void msc_ho_fsm_wait_request_ack(struct osmo_fsm_inst *fi, uint32_t event, void *data)
|
|
{
|
|
struct msc_a *msc_a = fi->priv;
|
|
|
|
switch (event) {
|
|
|
|
case MSC_HO_EV_RX_REQUEST_ACK:
|
|
msc_ho_rx_request_ack(msc_a, (struct msc_a_ran_dec_data*)data);
|
|
return;
|
|
|
|
case MSC_HO_EV_RX_FAILURE:
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_NO_RADIO_RESOURCE_AVAILABLE,
|
|
"Received Handover Failure message\n");
|
|
return;
|
|
|
|
default:
|
|
OSMO_ASSERT(false);
|
|
}
|
|
}
|
|
|
|
static void msc_ho_rtp_switch_to_new_cell(struct msc_a *msc_a);
|
|
|
|
void msc_ho_mncc_forward_cb(struct mncc_call *mncc_call, const union mncc_msg *mncc_msg, void *data)
|
|
{
|
|
struct msc_a *msc_a = data;
|
|
switch (mncc_msg->msg_type) {
|
|
case MNCC_RTP_CONNECT:
|
|
msc_a->ho.rtp_switched_to_new_cell = true;
|
|
return;
|
|
default:
|
|
return;
|
|
}
|
|
}
|
|
|
|
/* Initiate call forwarding via MNCC: call the Handover Number that the other MSC assigned. */
|
|
static int msc_ho_start_inter_msc_call_forwarding(struct msc_a *msc_a, struct msc_t *msc_t,
|
|
const struct msc_a_ran_dec_data *hra)
|
|
{
|
|
const struct osmo_gsup_message *e_info = hra->an_apdu->e_info;
|
|
struct gsm_mncc outgoing_call_req = {};
|
|
struct call_leg *cl = msc_a->cc.call_leg;
|
|
struct rtp_stream *rtp_to_ran = cl ? cl->rtp[RTP_TO_RAN] : NULL;
|
|
struct mncc_call *mncc_call;
|
|
|
|
if (!e_info || !e_info->msisdn_enc || !e_info->msisdn_enc_len) {
|
|
msc_ho_try_next_cell(msc_a,
|
|
"No Handover Number in Handover Request Acknowledge from remote MSC\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (!rtp_to_ran) {
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_EQUIPMENT_FAILURE, "Unexpected: no RTP stream is set up\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Backup old cell's RTP IP:port and codec data */
|
|
msc_a->ho.old_cell.ran_remote_rtp = rtp_to_ran->remote;
|
|
msc_a->ho.old_cell.codec = rtp_to_ran->codec;
|
|
|
|
/* Blindly taken over from an MNCC trace of existing code: send an all-zero CCCAP: */
|
|
outgoing_call_req.fields |= MNCC_F_CCCAP;
|
|
|
|
/* Called number */
|
|
outgoing_call_req.fields |= MNCC_F_CALLED;
|
|
outgoing_call_req.called.plan = 1; /* Empirical magic number. There seem to be no enum or defines for this.
|
|
* The only other place setting this apparently is gsm48_decode_called(). */
|
|
if (gsm48_decode_bcd_number2(outgoing_call_req.called.number, sizeof(outgoing_call_req.called.number),
|
|
e_info->msisdn_enc, e_info->msisdn_enc_len, 0)) {
|
|
msc_ho_try_next_cell(msc_a,
|
|
"Failed to decode Handover Number in Handover Request Acknowledge"
|
|
" from remote MSC\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (msc_a->cc.active_trans) {
|
|
outgoing_call_req.fields |= MNCC_F_BEARER_CAP;
|
|
outgoing_call_req.bearer_cap = msc_a->cc.active_trans->bearer_cap;
|
|
}
|
|
|
|
mncc_call = mncc_call_alloc(msc_a_vsub(msc_a),
|
|
msc_a->ho.fi,
|
|
MSC_HO_EV_MNCC_FORWARDING_COMPLETE,
|
|
MSC_HO_EV_MNCC_FORWARDING_FAILED,
|
|
msc_ho_mncc_forward_cb, msc_a);
|
|
|
|
mncc_call_set_rtp_stream(mncc_call, rtp_to_ran);
|
|
msc_a->ho.new_cell.mncc_forwarding_to_remote_ran = mncc_call;
|
|
return mncc_call_outgoing_start(mncc_call, &outgoing_call_req);
|
|
}
|
|
|
|
static void msc_ho_rx_request_ack(struct msc_a *msc_a, struct msc_a_ran_dec_data *hra)
|
|
{
|
|
struct msc_t *msc_t = msc_a_msc_t(msc_a);
|
|
struct ran_msg ran_enc_msg;
|
|
|
|
OSMO_ASSERT(hra->ran_dec);
|
|
OSMO_ASSERT(hra->an_apdu);
|
|
|
|
if (!msc_t) {
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_EQUIPMENT_FAILURE, "MSC-T role missing\n");
|
|
return;
|
|
}
|
|
|
|
if (!hra->ran_dec->handover_request_ack.rr_ho_command
|
|
|| !hra->ran_dec->handover_request_ack.rr_ho_command_len) {
|
|
msc_ho_try_next_cell(msc_a, "Missing mandatory IE in Handover Request Acknowledge:"
|
|
" L3 Info (RR Handover Command)\n");
|
|
return;
|
|
}
|
|
|
|
if (!hra->ran_dec->handover_request_ack.chosen_channel_present) {
|
|
LOG_HO(msc_a, LOGL_DEBUG, "No 'Chosen Channel' IE in Handover Request Ack\n");
|
|
msc_t->geran.chosen_channel = 0;
|
|
} else
|
|
msc_t->geran.chosen_channel = hra->ran_dec->handover_request_ack.chosen_channel;
|
|
|
|
if (!hra->ran_dec->handover_request_ack.chosen_encr_alg) {
|
|
LOG_HO(msc_a, LOGL_DEBUG, "No 'Chosen Encryption Algorithm' IE in Handover Request Ack\n");
|
|
msc_t->geran.chosen_encr_alg = 0;
|
|
} else {
|
|
msc_t->geran.chosen_encr_alg = hra->ran_dec->handover_request_ack.chosen_encr_alg;
|
|
if (msc_t->geran.chosen_encr_alg < 1 || msc_t->geran.chosen_encr_alg > 8) {
|
|
msc_ho_try_next_cell(msc_a, "Handover Request Ack: Invalid 'Chosen Encryption Algorithm': %u\n",
|
|
msc_t->geran.chosen_encr_alg);
|
|
return;
|
|
}
|
|
}
|
|
|
|
msc_t->geran.chosen_speech_version = hra->ran_dec->handover_request_ack.chosen_speech_version;
|
|
if (!msc_t->geran.chosen_speech_version)
|
|
LOG_HO(msc_a, LOGL_DEBUG, "No 'Chosen Speech Version' IE in Handover Request Ack\n");
|
|
|
|
/* Inter-MSC call forwarding? */
|
|
if (msc_a->ho.new_cell.type == MSC_NEIGHBOR_TYPE_REMOTE_MSC) {
|
|
if (msc_ho_start_inter_msc_call_forwarding(msc_a, msc_t, hra))
|
|
return;
|
|
}
|
|
|
|
msc_ho_fsm_state_chg(msc_a, MSC_HO_ST_WAIT_COMPLETE);
|
|
|
|
/* Forward the RR Handover Command composed by the new RAN peer down to the old RAN peer */
|
|
ran_enc_msg = (struct ran_msg){
|
|
.msg_type = RAN_MSG_HANDOVER_COMMAND,
|
|
.handover_command = {
|
|
.rr_ho_command = hra->ran_dec->handover_request_ack.rr_ho_command,
|
|
.rr_ho_command_len = hra->ran_dec->handover_request_ack.rr_ho_command_len,
|
|
},
|
|
};
|
|
|
|
if (msc_a_msg_down(msc_a, MSC_ROLE_I,
|
|
msc_a->ho.subsequent_ho ? MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_RESULT
|
|
: MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST,
|
|
&ran_enc_msg)) {
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_EQUIPMENT_FAILURE, "Failed to send Handover Command\n");
|
|
return;
|
|
}
|
|
|
|
msc_a->ho.new_cell.ran_remote_rtp = hra->ran_dec->handover_request_ack.remote_rtp;
|
|
if (osmo_sockaddr_str_is_nonzero(&msc_a->ho.new_cell.ran_remote_rtp)) {
|
|
LOG_HO(msc_a, LOGL_DEBUG, "Request Ack contains cell's RTP address " OSMO_SOCKADDR_STR_FMT "\n",
|
|
OSMO_SOCKADDR_STR_FMT_ARGS(&msc_a->ho.new_cell.ran_remote_rtp));
|
|
}
|
|
|
|
msc_a->ho.new_cell.codec_present = hra->ran_dec->handover_request_ack.codec_present;
|
|
msc_a->ho.new_cell.codec = hra->ran_dec->handover_request_ack.codec;
|
|
if (hra->ran_dec->handover_request_ack.codec_present) {
|
|
LOG_HO(msc_a, LOGL_DEBUG, "Request Ack contains codec %s\n",
|
|
osmo_mgcpc_codec_name(msc_a->ho.new_cell.codec));
|
|
}
|
|
}
|
|
|
|
static void msc_ho_rtp_switch_to_new_cell(struct msc_a *msc_a)
|
|
{
|
|
struct call_leg *cl = msc_a->cc.call_leg;
|
|
struct rtp_stream *rtp_to_ran = cl ? cl->rtp[RTP_TO_RAN] : NULL;
|
|
|
|
if (!rtp_to_ran) {
|
|
LOG_HO(msc_a, LOGL_DEBUG, "No RTP stream, nothing to switch\n");
|
|
return;
|
|
}
|
|
|
|
if (!osmo_sockaddr_str_is_nonzero(&msc_a->ho.new_cell.ran_remote_rtp)) {
|
|
LOG_HO(msc_a, LOGL_DEBUG, "New cell's RTP IP:port not yet known, not switching RTP stream\n");
|
|
return;
|
|
}
|
|
|
|
if (msc_a->ho.rtp_switched_to_new_cell) {
|
|
LOG_HO(msc_a, LOGL_DEBUG, "Already switched RTP to new cell\n");
|
|
return;
|
|
}
|
|
msc_a->ho.rtp_switched_to_new_cell = true;
|
|
|
|
/* Backup old cell's RTP IP:port and codec data */
|
|
msc_a->ho.old_cell.ran_remote_rtp = rtp_to_ran->remote;
|
|
msc_a->ho.old_cell.codec = rtp_to_ran->codec;
|
|
|
|
LOG_HO(msc_a, LOGL_DEBUG, "Switching RTP stream to new cell: from " OSMO_SOCKADDR_STR_FMT " to " OSMO_SOCKADDR_STR_FMT "\n",
|
|
OSMO_SOCKADDR_STR_FMT_ARGS(&msc_a->ho.old_cell.ran_remote_rtp),
|
|
OSMO_SOCKADDR_STR_FMT_ARGS(&msc_a->ho.new_cell.ran_remote_rtp));
|
|
|
|
/* If a previous forwarding to a remote MSC is still active, this now becomes no longer responsible for the RTP
|
|
* stream. */
|
|
if (msc_a->cc.mncc_forwarding_to_remote_ran) {
|
|
if (msc_a->cc.mncc_forwarding_to_remote_ran->rtps != rtp_to_ran) {
|
|
LOG_HO(msc_a, LOGL_ERROR,
|
|
"Unexpected state: previous MNCC forwarding not using RTP-to-RAN stream\n");
|
|
/* That would be weird, but carry on anyway... */
|
|
}
|
|
mncc_call_detach_rtp_stream(msc_a->cc.mncc_forwarding_to_remote_ran);
|
|
}
|
|
|
|
/* Switch over to the new peer */
|
|
rtp_stream_set_remote_addr(rtp_to_ran, &msc_a->ho.new_cell.ran_remote_rtp);
|
|
if (msc_a->ho.new_cell.codec_present)
|
|
rtp_stream_set_codec(rtp_to_ran, msc_a->ho.new_cell.codec);
|
|
else
|
|
LOG_HO(msc_a, LOGL_ERROR, "No codec is set\n");
|
|
rtp_stream_commit(rtp_to_ran);
|
|
}
|
|
|
|
static void msc_ho_rtp_rollback_to_old_cell(struct msc_a *msc_a)
|
|
{
|
|
struct call_leg *cl = msc_a->cc.call_leg;
|
|
struct rtp_stream *rtp_to_ran = cl ? cl->rtp[RTP_TO_RAN] : NULL;
|
|
|
|
if (!msc_a->ho.rtp_switched_to_new_cell) {
|
|
LOG_HO(msc_a, LOGL_DEBUG, "Not switched RTP to new cell yet, no need to roll back\n");
|
|
return;
|
|
}
|
|
|
|
if (!rtp_to_ran) {
|
|
LOG_HO(msc_a, LOGL_DEBUG, "No RTP stream, nothing to switch\n");
|
|
return;
|
|
}
|
|
|
|
if (!osmo_sockaddr_str_is_nonzero(&msc_a->ho.old_cell.ran_remote_rtp)) {
|
|
LOG_HO(msc_a, LOGL_DEBUG, "Have no RTP IP:port for the old cell, not switching back to\n");
|
|
return;
|
|
}
|
|
|
|
/* The new call forwarding to a remote MSC is no longer needed because the handover failed */
|
|
if (msc_a->ho.new_cell.mncc_forwarding_to_remote_ran)
|
|
mncc_call_detach_rtp_stream(msc_a->ho.new_cell.mncc_forwarding_to_remote_ran);
|
|
|
|
/* If before this handover, there was a call forwarding to a remote MSC in place, this now goes back into
|
|
* responsibility. */
|
|
if (msc_a->cc.mncc_forwarding_to_remote_ran)
|
|
mncc_call_set_rtp_stream(msc_a->cc.mncc_forwarding_to_remote_ran, rtp_to_ran);
|
|
|
|
msc_a->ho.rtp_switched_to_new_cell = false;
|
|
msc_a->ho.ready_to_switch_rtp = false;
|
|
LOG_HO(msc_a, LOGL_NOTICE, "Switching RTP back to old cell\n");
|
|
|
|
/* Switch back to the old cell */
|
|
rtp_stream_set_remote_addr(rtp_to_ran, &msc_a->ho.old_cell.ran_remote_rtp);
|
|
rtp_stream_set_codec(rtp_to_ran, msc_a->ho.old_cell.codec);
|
|
rtp_stream_commit(rtp_to_ran);
|
|
}
|
|
|
|
static void msc_ho_send_handover_succeeded(struct msc_a *msc_a)
|
|
{
|
|
struct ran_msg ran_enc_msg = {
|
|
.msg_type = RAN_MSG_HANDOVER_SUCCEEDED,
|
|
};
|
|
|
|
if (msc_a_msg_down(msc_a, MSC_ROLE_I, MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST, &ran_enc_msg))
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_EQUIPMENT_FAILURE, "Failed to send Handover Succeeded message\n");
|
|
}
|
|
|
|
static void msc_ho_fsm_wait_complete(struct osmo_fsm_inst *fi, uint32_t event, void *data)
|
|
{
|
|
struct msc_a *msc_a = fi->priv;
|
|
|
|
switch (event) {
|
|
|
|
case MSC_HO_EV_RX_DETECT:
|
|
msc_a->ho.ready_to_switch_rtp = true;
|
|
/* For inter-MSC, the mncc_fsm switches the rtp_stream upon MNCC_RTP_CONNECT.
|
|
* For inter-BSC, need to switch here to the address obtained from Handover Request Ack. */
|
|
if (msc_a->ho.new_cell.type == MSC_NEIGHBOR_TYPE_LOCAL_RAN_PEER)
|
|
msc_ho_rtp_switch_to_new_cell(msc_a);
|
|
msc_ho_send_handover_succeeded(msc_a);
|
|
return;
|
|
|
|
case MSC_HO_EV_RX_COMPLETE:
|
|
msc_ho_success(msc_a);
|
|
return;
|
|
|
|
case MSC_HO_EV_RX_FAILURE:
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_NO_RADIO_RESOURCE_AVAILABLE,
|
|
"Received Handover Failure message\n");
|
|
return;
|
|
|
|
case MSC_HO_EV_MNCC_FORWARDING_FAILED:
|
|
msc_ho_failed(msc_a, GSM0808_CAUSE_EQUIPMENT_FAILURE, "MNCC Forwarding failed\n");
|
|
return;
|
|
|
|
case MSC_HO_EV_MNCC_FORWARDING_COMPLETE:
|
|
return;
|
|
|
|
default:
|
|
OSMO_ASSERT(false);
|
|
}
|
|
}
|
|
|
|
static void msc_ho_fsm_cleanup(struct osmo_fsm_inst *fi, enum osmo_fsm_term_cause cause)
|
|
{
|
|
struct msc_a *msc_a = fi->priv;
|
|
struct msc_t *msc_t = msc_a_msc_t(msc_a);
|
|
|
|
/* paranoia */
|
|
if (msc_a->ho.fi != fi)
|
|
return;
|
|
|
|
/* Completely clear all handover state */
|
|
msc_a->ho = (struct msc_ho_state){};
|
|
|
|
if (msc_t)
|
|
msc_t_clear(msc_t);
|
|
}
|
|
|
|
static int msc_ho_fsm_timer_cb(struct osmo_fsm_inst *fi)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
#define S(x) (1 << (x))
|
|
|
|
static const struct osmo_fsm_state msc_ho_fsm_states[] = {
|
|
[MSC_HO_ST_REQUIRED] = {
|
|
.name = OSMO_STRINGIFY(MSC_HO_ST_REQUIRED),
|
|
.out_state_mask = 0
|
|
| S(MSC_HO_ST_REQUIRED)
|
|
| S(MSC_HO_ST_WAIT_REQUEST_ACK)
|
|
,
|
|
.onenter = msc_ho_fsm_required_onenter,
|
|
},
|
|
[MSC_HO_ST_WAIT_REQUEST_ACK] = {
|
|
.name = OSMO_STRINGIFY(MSC_HO_ST_WAIT_REQUEST_ACK),
|
|
.in_event_mask = 0
|
|
| S(MSC_HO_EV_RX_REQUEST_ACK)
|
|
| S(MSC_HO_EV_RX_FAILURE)
|
|
,
|
|
.out_state_mask = 0
|
|
| S(MSC_HO_ST_REQUIRED)
|
|
| S(MSC_HO_ST_WAIT_COMPLETE)
|
|
,
|
|
.onenter = msc_ho_fsm_wait_request_ack_onenter,
|
|
.action = msc_ho_fsm_wait_request_ack,
|
|
},
|
|
[MSC_HO_ST_WAIT_COMPLETE] = {
|
|
.name = OSMO_STRINGIFY(MSC_HO_ST_WAIT_COMPLETE),
|
|
.in_event_mask = 0
|
|
| S(MSC_HO_EV_RX_DETECT)
|
|
| S(MSC_HO_EV_RX_COMPLETE)
|
|
| S(MSC_HO_EV_RX_FAILURE)
|
|
| S(MSC_HO_EV_MNCC_FORWARDING_COMPLETE)
|
|
| S(MSC_HO_EV_MNCC_FORWARDING_FAILED)
|
|
,
|
|
.action = msc_ho_fsm_wait_complete,
|
|
},
|
|
};
|
|
|
|
static const struct value_string msc_ho_fsm_event_names[] = {
|
|
OSMO_VALUE_STRING(MSC_HO_EV_RX_REQUEST_ACK),
|
|
OSMO_VALUE_STRING(MSC_HO_EV_RX_DETECT),
|
|
OSMO_VALUE_STRING(MSC_HO_EV_RX_COMPLETE),
|
|
OSMO_VALUE_STRING(MSC_HO_EV_RX_FAILURE),
|
|
{}
|
|
};
|
|
|
|
struct osmo_fsm msc_ho_fsm = {
|
|
.name = "handover",
|
|
.states = msc_ho_fsm_states,
|
|
.num_states = ARRAY_SIZE(msc_ho_fsm_states),
|
|
.log_subsys = DHO,
|
|
.event_names = msc_ho_fsm_event_names,
|
|
.timer_cb = msc_ho_fsm_timer_cb,
|
|
.cleanup = msc_ho_fsm_cleanup,
|
|
};
|