Fill Last Used E-UTRAN PLMN Id when in CSFB

Since recently, osmo-bsc behaves strictly as per specs, meaning it will
only send the "Cell selection indicator after release of all TCH and SDCCH IE"
in RR Channel Release iff:
* "Last Used E-UTRAN PLMN Id" was received in the CommonID sent MSC->BSC
* "Last Used E-UTRAN PLMN Id" was received insider "old BSS to new BSS Information"
  in the HandoverRequest sent MSC->BSC.
On the other hand, CSFB_Indicator from ClearCommand MSC->BSC is nw
ignored and not taken into account.

Hence, let's update osmo-msc to also behave correctly by sending the
Last Used E-UTRAN PLMN ID at CommonID tx time to avoid regressions in
CSFB support when running against newer osmo-bsc.

Let's keep sending the CSFB Indicator in ClearCommand as we used too, in
order to keep compatibility with older BSCs (as per spec).

Related: SYS#5337
Change-Id: Ic5f175b179973d0a50d94f00e15f5a3e332605fc
changes/15/23915/4
Pau Espin 2 years ago
parent a361cab54a
commit 6710670cb1
  1. 2
      include/osmocom/msc/ran_msg.h
  2. 4
      include/osmocom/msc/vlr.h
  3. 2
      include/osmocom/msc/vlr_sgs.h
  4. 9
      src/libmsc/gsm_04_08.c
  5. 5
      src/libmsc/msc_a.c
  6. 6
      src/libmsc/ran_msg_a.c
  7. 42
      src/libmsc/sgs_iface.c
  8. 17
      src/libvlr/vlr.c
  9. 4
      src/libvlr/vlr_sgs.c

@ -220,6 +220,8 @@ struct ran_msg {
} cipher_mode_reject;
struct {
const char *imsi;
bool last_eutran_plmn_present;
struct osmo_plmn_id last_eutran_plmn;
} common_id;
struct {
enum gsm48_reject_value cause;

@ -193,6 +193,8 @@ struct vlr_subscr {
vlr_sgs_lu_mminfo_cb_t mminfo_cb;
enum sgsap_service_ind paging_serv_ind;
struct osmo_timer_list Ts5;
bool last_eutran_plmn_present;
struct osmo_plmn_id last_eutran_plmn;
} sgs;
struct osmo_gsm48_classmark classmark;
@ -398,6 +400,8 @@ void vlr_subscr_set_imsi(struct vlr_subscr *vsub, const char *imsi);
void vlr_subscr_set_imei(struct vlr_subscr *vsub, const char *imei);
void vlr_subscr_set_imeisv(struct vlr_subscr *vsub, const char *imeisv);
void vlr_subscr_set_msisdn(struct vlr_subscr *vsub, const char *msisdn);
void vlr_subscr_set_last_used_eutran_plmn_id(struct vlr_subscr *vsub,
const struct osmo_plmn_id *last_eutran_plmn);
bool vlr_subscr_matches_imsi(struct vlr_subscr *vsub, const char *imsi);
bool vlr_subscr_matches_tmsi(struct vlr_subscr *vsub, uint32_t tmsi);

@ -97,7 +97,7 @@ void vlr_sgs_reset(struct vlr_instance *vlr);
int vlr_sgs_loc_update(struct vlr_instance *vlr, struct vlr_sgs_cfg *cfg,
vlr_sgs_lu_response_cb_t response_cb, vlr_sgs_lu_paging_cb_t paging_cb,
vlr_sgs_lu_mminfo_cb_t mminfo_cb, char *mme_name, enum vlr_lu_type type, const char *imsi,
struct osmo_location_area_id *new_lai);
struct osmo_location_area_id *new_lai, struct osmo_plmn_id *last_eutran_plmn);
void vlr_sgs_loc_update_acc_sent(struct vlr_subscr *vsub);
void vlr_sgs_loc_update_rej_sent(struct vlr_subscr *vsub);
void vlr_sgs_detach(struct vlr_instance *vlr, const char *imsi, bool eps);

@ -1368,12 +1368,19 @@ int msc_vlr_tx_cm_serv_acc(void *msc_conn_ref, enum osmo_cm_service_type cm_serv
static int msc_vlr_tx_common_id(void *msc_conn_ref)
{
struct msc_a *msc_a = msc_conn_ref;
struct vlr_subscr *vsub = msc_a_vsub(msc_a);
struct ran_msg msg = {
.msg_type = RAN_MSG_COMMON_ID,
.common_id = {
.imsi = msc_a_vsub(msc_a)->imsi,
.imsi = vsub->imsi,
.last_eutran_plmn_present = vsub->sgs.last_eutran_plmn_present,
},
};
if (vsub->sgs.last_eutran_plmn_present) {
memcpy(&msg.common_id.last_eutran_plmn, &vsub->sgs.last_eutran_plmn,
sizeof(vsub->sgs.last_eutran_plmn));
}
return msc_a_ran_down(msc_a, MSC_ROLE_I, &msg);
}

@ -1648,8 +1648,13 @@ int msc_tx_common_id(struct msc_a *msc_a, enum msc_role to_role)
.msg_type = RAN_MSG_COMMON_ID,
.common_id = {
.imsi = vsub->imsi,
.last_eutran_plmn_present = vsub->sgs.last_eutran_plmn_present,
},
};
if (vsub->sgs.last_eutran_plmn_present) {
memcpy(&msg.common_id.last_eutran_plmn, &vsub->sgs.last_eutran_plmn,
sizeof(vsub->sgs.last_eutran_plmn));
}
return msc_a_ran_down(msc_a, to_role, &msg);
}

@ -1218,7 +1218,11 @@ static struct msgb *_ran_a_encode(struct osmo_fsm_inst *caller_fi, const struct
return ran_a_make_assignment_command(caller_fi, &ran_enc_msg->assignment_command);
case RAN_MSG_COMMON_ID:
return gsm0808_create_common_id(ran_enc_msg->common_id.imsi, NULL, NULL);
return gsm0808_create_common_id(ran_enc_msg->common_id.imsi, NULL,
ran_enc_msg->common_id.last_eutran_plmn_present ?
&ran_enc_msg->common_id.last_eutran_plmn :
NULL
);
case RAN_MSG_CIPHER_MODE_COMMAND:
return ran_a_make_cipher_mode_command(caller_fi, &ran_enc_msg->cipher_mode_command);

@ -608,12 +608,14 @@ static int sgs_rx_loc_upd_req(struct sgs_connection *sgc, struct msgb *msg, cons
char *mme_name;
struct vlr_sgs_cfg vlr_sgs_cfg;
struct vlr_subscr *vsub;
struct osmo_plmn_id last_eutran_plmn_buf, *last_eutran_plmn = NULL;
/* Check for lingering connections */
vsub = vlr_subscr_find_by_imsi(gsm_network->vlr, imsi, __func__);
if (vsub) {
subscr_conn_toss(vsub);
vlr_subscr_put(vsub, __func__);
vsub = NULL;
}
/* Determine MME-Name */
@ -639,11 +641,29 @@ static int sgs_rx_loc_upd_req(struct sgs_connection *sgc, struct msgb *msg, cons
return sgs_tx_status(sgc, imsi, SGSAP_SGS_CAUSE_MISSING_MAND_IE, msg, SGSAP_IE_LAI);
gsm48_decode_lai2(gsm48_lai, &new_lai);
/* 3GPP TS 23.272 sec 4.3.3 (CSFB):
* "During the SGs location update procedure, obtaining the last used LTE PLMN ID via TAI"
*/
if (TLVP_PRES_LEN(tp, SGSAP_IE_TAI, 3)) {
last_eutran_plmn = &last_eutran_plmn_buf;
osmo_plmn_from_bcd(TLVP_VAL(tp, SGSAP_IE_TAI), last_eutran_plmn);
/* TODO: we could also gather the TAC from here, but we don't need it yet */
} else if (TLVP_PRES_LEN(tp, SGSAP_IE_EUTRAN_CGI, 3)) {
/* Since TAI is optional, let's try harder getting Last Used
* E-UTRAN PLMN ID by fetching it from E-UTRAN CGI */
last_eutran_plmn = &last_eutran_plmn_buf;
osmo_plmn_from_bcd(TLVP_VAL(tp, SGSAP_IE_EUTRAN_CGI), last_eutran_plmn);
/* TODO: we could also gather the ECI from here, but we don't need it yet */
} else {
LOGSGC(sgc, LOGL_INFO, "Receiving SGsAP-LOCATION-UPDATE-REQUEST without TAI nor "
"E-CGI IEs, fast fallback GERAN->EUTRAN won't be possible!\n");
}
/* Perform actual location update */
memcpy(vlr_sgs_cfg.timer, sgc->sgs->cfg.timer, sizeof(vlr_sgs_cfg.timer));
memcpy(vlr_sgs_cfg.counter, sgc->sgs->cfg.counter, sizeof(vlr_sgs_cfg.counter));
rc = vlr_sgs_loc_update(gsm_network->vlr, &vlr_sgs_cfg, sgs_tx_loc_upd_resp_cb, sgs_iface_tx_paging,
sgs_tx_mm_info_cb, mme_name, type, imsi, &new_lai);
sgs_tx_mm_info_cb, mme_name, type, imsi, &new_lai, last_eutran_plmn);
if (rc != 0) {
resp = gsm29118_create_lu_rej(imsi, SGSAP_SGS_CAUSE_IMSI_UNKNOWN, NULL);
sgs_tx(sgc, resp);
@ -905,6 +925,26 @@ static int sgs_rx_csfb_ind(struct sgs_connection *sgc, struct msgb *msg, const s
if (!vsub)
return sgs_tx_status(sgc, imsi, SGSAP_SGS_CAUSE_IMSI_UNKNOWN, msg, SGSAP_IE_IMSI);
/* 3GPP TS 23.272 sec 4.3.3 (CSFB):
* "During the SGs location update procedure, obtaining the last used LTE PLMN ID via TAI"
*/
vsub->sgs.last_eutran_plmn_present = TLVP_PRES_LEN(tp, SGSAP_IE_EUTRAN_CGI, 3);
if (TLVP_PRES_LEN(tp, SGSAP_IE_TAI, 3)) {
vsub->sgs.last_eutran_plmn_present = true;
osmo_plmn_from_bcd(TLVP_VAL(tp, SGSAP_IE_TAI), &vsub->sgs.last_eutran_plmn);
/* TODO: we could also gather the TAC from here, but we don't need it yet */
} else if (TLVP_PRES_LEN(tp, SGSAP_IE_EUTRAN_CGI, 3)) {
/* Since TAI is optional, let's try harder getting Last Used
* E-UTRAN PLMN ID by fetching it from E-UTRAN CGI */
vsub->sgs.last_eutran_plmn_present = true;
osmo_plmn_from_bcd(TLVP_VAL(tp, SGSAP_IE_EUTRAN_CGI), &vsub->sgs.last_eutran_plmn);
/* TODO: we could also gather the ECI from here, but we don't need it yet */
} else if (!vsub->sgs.last_eutran_plmn_present) {
LOGSGC(sgc, LOGL_INFO, "Receiving SGsAP-MO-CSFB-INDICATION without TAI nor "
"E-CGI IEs, and they are not known from previous SGsAP-LOCATION-UPDATE-REQUEST. "
"Fast fallback GERAN->EUTRAN won't be possible!\n");
}
/* Check for lingering connections */
subscr_conn_toss(vsub);

@ -476,6 +476,23 @@ void vlr_subscr_set_msisdn(struct vlr_subscr *vsub, const char *msisdn)
vsub->imsi, vsub->msisdn);
}
void vlr_subscr_set_last_used_eutran_plmn_id(struct vlr_subscr *vsub,
const struct osmo_plmn_id *last_eutran_plmn)
{
if (!vsub)
return;
if (last_eutran_plmn) {
vsub->sgs.last_eutran_plmn_present = true;
memcpy(&vsub->sgs.last_eutran_plmn, last_eutran_plmn, sizeof(*last_eutran_plmn));
} else {
vsub->sgs.last_eutran_plmn_present = false;
}
DEBUGP(DVLR, "set Last E-UTRAN PLMN ID on subscriber: %s\n",
vsub->sgs.last_eutran_plmn_present ?
osmo_plmn_name(&vsub->sgs.last_eutran_plmn) :
"(none)");
}
bool vlr_subscr_matches_imsi(struct vlr_subscr *vsub, const char *imsi)
{
return vsub && imsi && vsub->imsi[0] && !strcmp(vsub->imsi, imsi);

@ -68,11 +68,12 @@ void vlr_sgs_reset(struct vlr_instance *vlr)
* \param[in] type location update type (normal or IMSI attach).
* \param[in] imsi mobile identity (IMSI).
* \param[in] new_lai identifier of the new location area.
* \param[in] last_eutran_plnm_id Last E-UTRAN PLMN ID (can be NULL).
* \returns 0 in case of success, -EINVAL in case of error. */
int vlr_sgs_loc_update(struct vlr_instance *vlr, struct vlr_sgs_cfg *cfg,
vlr_sgs_lu_response_cb_t response_cb, vlr_sgs_lu_paging_cb_t paging_cb,
vlr_sgs_lu_mminfo_cb_t mminfo_cb, char *mme_name, enum vlr_lu_type type, const char *imsi,
struct osmo_location_area_id *new_lai)
struct osmo_location_area_id *new_lai, struct osmo_plmn_id *last_eutran_plmn)
{
struct vlr_subscr *vsub = NULL;
@ -93,6 +94,7 @@ int vlr_sgs_loc_update(struct vlr_instance *vlr, struct vlr_sgs_cfg *cfg,
vsub->sgs.paging_cb = paging_cb;
vsub->sgs.mminfo_cb = mminfo_cb;
vlr_subscr_set_imsi(vsub, imsi);
vlr_subscr_set_last_used_eutran_plmn_id(vsub, last_eutran_plmn);
osmo_strlcpy(vsub->sgs.mme_name, mme_name, sizeof(vsub->sgs.mme_name));
osmo_fsm_inst_dispatch(vsub->sgs_fsm, SGS_UE_E_RX_LU_FROM_MME, NULL);

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