PentHertz
/
srsLTE
mirror of https://github.com/PentHertz/srsLTE.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Reject TAU to force UE to reconnect

This commit is contained in:
Merlin Chlosta 2019-07-23 16:23:54 +02:00 committed by Pedro Alvarez
parent a6105a3020
commit c2e95b1e2a
2 changed files with 46 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
srsepc/hdr/mme/nas.h
View File

@ -247,6 +247,7 @@ public:
bool pack_identity_request(srslte::byte_buffer_t* nas_buffer);
bool pack_emm_information(srslte::byte_buffer_t* nas_buffer);
bool pack_service_reject(srslte::byte_buffer_t* nas_buffer, uint8_t emm_cause);
bool pack_tracking_area_update_reject(srslte::byte_buffer_t* nas_buffer, uint8_t emm_cause);
bool pack_attach_accept(srslte::byte_buffer_t* nas_buffer);
/* Security functions */

57
srsepc/src/mme/nas.cc
View File

@ -776,6 +776,8 @@ bool nas::handle_tracking_area_update_request(uint32_t m_tmsi,
nas_if_t itf,
srslte::log* nas_log)
{
srslte::byte_buffer_pool* pool = srslte::byte_buffer_pool::get_instance();
nas_log->info("Tracking Area Update Request -- S-TMSI 0x%x\n", m_tmsi);
nas_log->console("Tracking Area Update Request -- S-TMSI 0x%x\n", m_tmsi);
nas_log->info("Tracking Area Update Request -- eNB UE S1AP Id %d\n", enb_ue_s1ap_id);
@ -789,20 +791,17 @@ bool nas::handle_tracking_area_update_request(uint32_t m_tmsi,
hss_interface_nas* hss = itf.hss;
gtpc_interface_nas* gtpc = itf.gtpc;
uint64_t imsi = s1ap->find_imsi_from_m_tmsi(m_tmsi);
if (imsi == 0) {
nas_log->console("Could not find IMSI from M-TMSI. M-TMSI 0x%x\n", m_tmsi);
nas_log->error("Could not find IMSI from M-TMSI. M-TMSI 0x%x\n", m_tmsi);
return true;
}
// TODO don't search for NAS ctxt, just send that reject
// with context we could enable integrity protection
nas* nas_ctx = s1ap->find_nas_ctx_from_imsi(imsi);
emm_ctx_t* emm_ctx = &nas_ctx->m_emm_ctx;
ecm_ctx_t* ecm_ctx = &nas_ctx->m_ecm_ctx;
nas nas_tmp(args, itf, nas_log);
nas_tmp.m_ecm_ctx.enb_ue_s1ap_id = enb_ue_s1ap_id;
nas_tmp.m_ecm_ctx.mme_ue_s1ap_id = s1ap->get_next_mme_ue_s1ap_id();
sec_ctx_t* sec_ctx = &nas_ctx->m_sec_ctx;
sec_ctx->ul_nas_count++; // Increment the NAS count, not to break the security ctx
srslte::byte_buffer_t* nas_tx = pool->allocate();
nas_tmp.pack_tracking_area_update_reject(nas_tx, LIBLTE_MME_EMM_CAUSE_IMPLICITLY_DETACHED);
s1ap->send_downlink_nas_transport(enb_ue_s1ap_id, nas_tmp.m_ecm_ctx.mme_ue_s1ap_id, nas_tx, *enb_sri);
pool->deallocate(nas_tx);
return true;
}
@ -1150,6 +1149,18 @@ bool nas::handle_tracking_area_update_request(srslte::byte_buffer_t* nas_rx)
m_nas_log->console("Warning: Tracking Area Update Request messages not handled yet.\n");
m_nas_log->warning("Warning: Tracking Area Update Request messages not handled yet.\n");
srslte::byte_buffer_pool* pool = srslte::byte_buffer_pool::get_instance();
srslte::byte_buffer_t* nas_tx;
/* TAU handling unsupported, therefore send TAU reject with cause IMPLICITLY DETACHED.
* this will trigger full re-attach by the UE, instead of going to a TAU request loop */
nas_tx = pool->allocate();
// TODO we could enable integrity protection in some cases, but UE should comply anyway
pack_tracking_area_update_reject(nas_tx, LIBLTE_MME_EMM_CAUSE_IMPLICITLY_DETACHED);
// Send reply
m_s1ap->send_downlink_nas_transport(m_ecm_ctx.enb_ue_s1ap_id, m_ecm_ctx.mme_ue_s1ap_id, nas_tx, m_ecm_ctx.enb_sri);
pool->deallocate(nas_tx);
return true;
}
@ -1561,6 +1572,28 @@ bool nas::pack_service_reject(srslte::byte_buffer_t* nas_buffer, uint8_t emm_cau
return true;
}
bool nas::pack_tracking_area_update_reject(srslte::byte_buffer_t* nas_buffer, uint8_t emm_cause)
{
LIBLTE_MME_TRACKING_AREA_UPDATE_REJECT_MSG_STRUCT tau_rej;
tau_rej.t3446_present = false;
tau_rej.t3446 = 0;
tau_rej.emm_cause = emm_cause;
if (emm_cause == LIBLTE_MME_EMM_CAUSE_CONGESTION) {
// Standard would want T3446 set in this case
m_nas_log->error("Tracking Area Update Reject EMM Cause set to \"CONGESTION\", but back-off timer not set.\n");
}
LIBLTE_ERROR_ENUM err = liblte_mme_pack_tracking_area_update_reject_msg(&tau_rej, LIBLTE_MME_SECURITY_HDR_TYPE_PLAIN_NAS, 0,
(LIBLTE_BYTE_MSG_STRUCT*)nas_buffer);
if (err != LIBLTE_SUCCESS) {
m_nas_log->error("Error packing Tracking Area Update Reject\n");
m_nas_log->console("Error packing Tracking Area Update Reject\n");
return false;
}
return true;
}
/************************
*
* Security Functions