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SCCP N-PCSTATE: trigger MSC status on PC availability 

Related: SYS#6319
Related: Ia1aea4e33230d6a685b72ea5ba20dd9c7d265d44 osmo-ttcn3-hacks
Related: Ib4a5330df30a73e744c316898817b2fa3271d75e osmo-ttcn3-hacks
Change-Id: I3a0869598b8395601a16d78dbc46eec400c0ea84
This commit is contained in:
Neels Hofmeyr 2023-03-30 05:18:53 +02:00 committed by neels
parent ba6fd4f8e4
commit 8f8af40974
3 changed files with 111 additions and 1 deletions
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1
include/osmocom/bsc/bssmap_reset.h
View File

@ -28,4 +28,5 @@ struct bssmap_reset {
struct bssmap_reset *bssmap_reset_alloc(void *ctx, const char *label, const struct bssmap_reset_cfg *cfg);
bool bssmap_reset_is_conn_ready(const struct bssmap_reset *bssmap_reset);
void bssmap_reset_resend_reset(struct bssmap_reset *bssmap_reset);
void bssmap_reset_set_disconnected(struct bssmap_reset *bssmap_reset);
void bssmap_reset_term_and_free(struct bssmap_reset *bssmap_reset);

6
src/osmo-bsc/bssmap_reset.c
View File

@ -251,6 +251,12 @@ void bssmap_reset_resend_reset(struct bssmap_reset *bssmap_reset)
osmo_fsm_inst_state_chg_ms(bssmap_reset->fi, BSSMAP_RESET_ST_DISC, 1, 0);
}
void bssmap_reset_set_disconnected(struct bssmap_reset *bssmap_reset)
{
/* Go to disconnected state, with the normal RESET timeout to re-send RESET. */
bssmap_reset_fsm_state_chg(bssmap_reset->fi, BSSMAP_RESET_ST_DISC);
}
static __attribute__((constructor)) void bssmap_reset_fsm_init(void)
{
OSMO_ASSERT(osmo_fsm_register(&bssmap_reset_fsm) == 0);

105
src/osmo-bsc/osmo_bsc_sigtran.c
View File

@ -36,6 +36,7 @@
#include <osmocom/bsc/gsm_data.h>
#include <osmocom/bsc/bts.h>
#include <osmocom/bsc/paging.h>
#include <osmocom/bsc/bssmap_reset.h>
#include <osmocom/mgcp_client/mgcp_common.h>
/* A pointer to a list with all involved MSCs
@ -92,7 +93,7 @@ void osmo_bsc_sigtran_tx_reset_ack(const struct bsc_msc_data *msc)
&msc->a.msc_addr, msg);
}
/* Find an MSC by its sigtran point code */
/* Find an MSC by its remote SCCP address */
static struct bsc_msc_data *get_msc_by_addr(const struct osmo_sccp_addr *msc_addr)
{
struct osmo_ss7_instance *ss7;
@ -107,6 +108,21 @@ static struct bsc_msc_data *get_msc_by_addr(const struct osmo_sccp_addr *msc_add
return NULL;
}
/* Find an MSC by its remote sigtran point code on a given cs7 instance. */
static struct bsc_msc_data *get_msc_by_pc(struct osmo_ss7_instance *cs7, uint32_t pc)
{
struct bsc_msc_data *msc;
llist_for_each_entry(msc, msc_list, entry) {
if (msc->a.cs7_instance != cs7->cfg.id)
continue;
if ((msc->a.msc_addr.presence & OSMO_SCCP_ADDR_T_PC) == 0)
continue;
if (msc->a.msc_addr.pc == pc)
return msc;
}
return NULL;
}
/* Received data from MSC, use the connection id which MSC it is */
static int handle_data_from_msc(struct gsm_subscriber_connection *conn, struct msgb *msg)
{
@ -188,6 +204,89 @@ refuse:
return rc;
}
static void handle_pcstate_ind(struct osmo_ss7_instance *cs7, const struct osmo_scu_pcstate_param *pcst)
{
struct bsc_msc_data *msc;
bool connected;
bool disconnected;
LOGP(DMSC, LOGL_DEBUG, "N-PCSTATE ind: affected_pc=%u sp_status=%d remote_sccp_status=%d\n",
pcst->affected_pc, pcst->sp_status, pcst->remote_sccp_status);
/* If we don't care about that point-code, ignore PCSTATE. */
msc = get_msc_by_pc(cs7, pcst->affected_pc);
if (!msc)
return;
/* See if this marks the point code to have become available, or to have been lost.
*
* I want to detect two events:
* - connection event (both indicators say PC is reachable).
* - disconnection event (at least one indicator says the PC is not reachable).
*
* There are two separate incoming indicators with various possible values -- the incoming events can be:
*
* - neither connection nor disconnection indicated -- just indicating congestion
* connected == false, disconnected == false --> do nothing.
* - both incoming values indicate that we are connected
* --> trigger connected
* - both indicate we are disconnected
* --> trigger disconnected
* - one value indicates 'connected', the other indicates 'disconnected'
* --> trigger disconnected
*
* Congestion could imply that we're connected, but it does not indicate that a PC's reachability changed, so no need to
* trigger on that.
*/
connected = false;
disconnected = false;
switch (pcst->sp_status) {
case OSMO_SCCP_SP_S_ACCESSIBLE:
connected = true;
break;
case OSMO_SCCP_SP_S_INACCESSIBLE:
disconnected = true;
break;
default:
case OSMO_SCCP_SP_S_CONGESTED:
/* Neither connecting nor disconnecting */
break;
}
switch (pcst->remote_sccp_status) {
case OSMO_SCCP_REM_SCCP_S_AVAILABLE:
if (!disconnected)
connected = true;
break;
case OSMO_SCCP_REM_SCCP_S_UNAVAILABLE_UNKNOWN:
case OSMO_SCCP_REM_SCCP_S_UNEQUIPPED:
case OSMO_SCCP_REM_SCCP_S_INACCESSIBLE:
disconnected = true;
connected = false;
break;
default:
case OSMO_SCCP_REM_SCCP_S_CONGESTED:
/* Neither connecting nor disconnecting */
break;
}
if (disconnected && a_reset_conn_ready(msc)) {
LOGP(DMSC, LOGL_NOTICE,
"(msc%d) now unreachable: N-PCSTATE ind: pc=%u sp_status=%d remote_sccp_status=%d\n",
msc->nr, pcst->affected_pc, pcst->sp_status, pcst->remote_sccp_status);
/* A previously usable MSC has disconnected. Kick the BSSMAP back to DISC state. */
bssmap_reset_set_disconnected(msc->a.bssmap_reset);
} else if (connected && !a_reset_conn_ready(msc)) {
LOGP(DMSC, LOGL_NOTICE,
"(msc%d) now available: N-PCSTATE ind: pc=%u sp_status=%d remote_sccp_status=%d\n",
msc->nr, pcst->affected_pc, pcst->sp_status, pcst->remote_sccp_status);
/* A previously unusable MSC has become reachable. Trigger immediate BSSMAP RESET -- we would resend a
* RESET either way, but we might as well do it now to speed up connecting. */
bssmap_reset_resend_reset(msc->a.bssmap_reset);
}
}
/* Callback function, called by the SCCP stack when data arrives */
static int sccp_sap_up(struct osmo_prim_hdr *oph, void *_scu)
{
@ -255,6 +354,10 @@ static int sccp_sap_up(struct osmo_prim_hdr *oph, void *_scu)
}
break;
case OSMO_PRIM(OSMO_SCU_PRIM_N_PCSTATE, PRIM_OP_INDICATION):
handle_pcstate_ind(osmo_sccp_get_ss7(sccp), &scu_prim->u.pcstate);
break;
default:
LOGP(DMSC, LOGL_ERROR, "Unhandled SIGTRAN operation %s on primitive %u\n",
get_value_string(osmo_prim_op_names, oph->operation), oph->primitive);