From 1616c0933583b42c75bc2634618b5c1359160be2 Mon Sep 17 00:00:00 2001 From: Andre Puschmann Date: Thu, 6 Jan 2022 19:04:18 +0100 Subject: [PATCH] gnb,rrc: handle RRC reestablishment request implement basic support for sending RRC reestablishment --- srsgnb/hdr/stack/rrc/rrc_nr.h | 3 + srsgnb/hdr/stack/rrc/rrc_nr_ue.h | 6 ++ srsgnb/src/stack/rrc/rrc_nr.cc | 16 ++++ srsgnb/src/stack/rrc/rrc_nr_ue.cc | 141 +++++++++++++++++++++++++++++- 4 files changed, 165 insertions(+), 1 deletion(-) diff --git a/srsgnb/hdr/stack/rrc/rrc_nr.h b/srsgnb/hdr/stack/rrc/rrc_nr.h index 413dadf83..353176025 100644 --- a/srsgnb/hdr/stack/rrc/rrc_nr.h +++ b/srsgnb/hdr/stack/rrc/rrc_nr.h @@ -160,6 +160,9 @@ private: // TS 38.331, 5.3.3 - RRC connection establishment void handle_rrc_setup_request(uint16_t rnti, const asn1::rrc_nr::rrc_setup_request_s& msg); + // TS 38.331, 5.3.7 RRC connection reestablishment + void handle_rrc_reest_request(uint16_t rnti, const asn1::rrc_nr::rrc_reest_request_s& msg); + /// This gets called by rrc_nr::sgnb_addition_request and WILL NOT TRIGGER the RX MSG3 activity timer int add_user(uint16_t rnti, const sched_nr_ue_cfg_t& uecfg, bool start_msg3_timer); diff --git a/srsgnb/hdr/stack/rrc/rrc_nr_ue.h b/srsgnb/hdr/stack/rrc/rrc_nr_ue.h index 99ca94f07..f5fb3a820 100644 --- a/srsgnb/hdr/stack/rrc/rrc_nr_ue.h +++ b/srsgnb/hdr/stack/rrc/rrc_nr_ue.h @@ -65,6 +65,9 @@ public: /** TS 38.331 - 5.3.5 RRC reconfiguration */ void handle_rrc_reconfiguration_complete(const asn1::rrc_nr::rrc_recfg_complete_s& msg); + /** TS 38.331 - 5.3.7 RRC connection reestablishment */ + void handle_rrc_reest_request(const asn1::rrc_nr::rrc_reest_request_s& msg); + /** TS 38.331 - 5.3.8 Connection Release */ void send_rrc_release(); @@ -91,6 +94,9 @@ private: void send_rrc_setup(); void send_rrc_reject(uint8_t reject_wait_time_secs); + /** TS 38.331 - 5.3.7 RRC connection reestablishment */ + void send_connection_reest(uint8_t ncc); + /// Update PDCP bearers based on ASN1 structs passed to the UE int update_pdcp_bearers(const asn1::rrc_nr::radio_bearer_cfg_s& radio_bearer_diff, const asn1::rrc_nr::cell_group_cfg_s& cell_group_diff); diff --git a/srsgnb/src/stack/rrc/rrc_nr.cc b/srsgnb/src/stack/rrc/rrc_nr.cc index 1b3df68f6..0c6a55ab4 100644 --- a/srsgnb/src/stack/rrc/rrc_nr.cc +++ b/srsgnb/src/stack/rrc/rrc_nr.cc @@ -483,6 +483,9 @@ void rrc_nr::handle_ul_ccch(uint16_t rnti, srsran::const_byte_span pdu) case ul_ccch_msg_type_c::c1_c_::types_opts::rrc_setup_request: handle_rrc_setup_request(rnti, ul_ccch_msg.msg.c1().rrc_setup_request()); break; + case ul_ccch_msg_type_c::c1_c_::types_opts::rrc_reest_request: + handle_rrc_reest_request(rnti, ul_ccch_msg.msg.c1().rrc_reest_request()); + break; default: log_rx_pdu_fail(rnti, srb_to_lcid(lte_srb::srb0), pdu, "Unsupported UL-CCCH message type"); // TODO Remove user @@ -548,6 +551,19 @@ void rrc_nr::handle_rrc_setup_request(uint16_t rnti, const asn1::rrc_nr::rrc_set u.handle_rrc_setup_request(msg); } +void rrc_nr::handle_rrc_reest_request(uint16_t rnti, const asn1::rrc_nr::rrc_reest_request_s& msg) +{ + auto ue_it = users.find(rnti); + + // TODO: Defer creation of ue to this point + if (ue_it == users.end()) { + logger.error("%s received for inexistent rnti=0x%x", "UL-CCCH", rnti); + return; + } + ue& u = *ue_it->second; + u.handle_rrc_reest_request(msg); +} + /******************************************************************************* PDCP interface *******************************************************************************/ diff --git a/srsgnb/src/stack/rrc/rrc_nr_ue.cc b/srsgnb/src/stack/rrc/rrc_nr_ue.cc index 384d0474e..6589eee96 100644 --- a/srsgnb/src/stack/rrc/rrc_nr_ue.cc +++ b/srsgnb/src/stack/rrc/rrc_nr_ue.cc @@ -15,6 +15,7 @@ #include "srsgnb/hdr/stack/rrc/rrc_nr_config_utils.h" #include "srsran/asn1/rrc_nr_utils.h" #include "srsran/common/bearer_manager.h" +#include "srsran/common/standard_streams.h" #include "srsran/common/string_helpers.h" using namespace asn1::rrc_nr; @@ -883,6 +884,129 @@ void rrc_nr::ue::handle_rrc_setup_request(const asn1::rrc_nr::rrc_setup_request_ set_activity_timeout(UE_INACTIVITY_TIMEOUT); } +void rrc_nr::ue::handle_rrc_reest_request(const asn1::rrc_nr::rrc_reest_request_s& msg) +{ + uint32_t old_rnti = msg.rrc_reest_request.ue_id.c_rnti; + uint16_t pci = msg.rrc_reest_request.ue_id.pci; + + // Log event + parent->logger.debug("rnti=0x%x, phyid=0x%x, smac=0x%x, cause=%s", + old_rnti, + pci, + (uint32_t)msg.rrc_reest_request.ue_id.short_mac_i.to_number(), + msg.rrc_reest_request.reest_cause.to_string()); + + // Check AMF connection + const uint8_t max_wait_time_secs = 16; + if (not parent->ngap->is_amf_connected()) { + logger.error("AMF not connected. Sending Connection Reject."); + send_rrc_reject(max_wait_time_secs); + return; + } + + // Allocate PUCCH resources and reject if not available + if (not init_pucch()) { + logger.warning("Could not allocate PUCCH resources for rnti=0x%x. Sending RRC Reject.", rnti); + send_rrc_reject(max_wait_time_secs); + return; + } + + if (not is_idle()) { + // The created RNTI has to receive ReestablishmentRequest as first message + parent->logger.error( + "Could not reestablish connection for rnti=0x%x. Cause: old rnti=0x%x is not in RRC_IDLE.", rnti, old_rnti); + send_rrc_reject(max_wait_time_secs); + return; + } + + auto old_ue_it = parent->users.find(old_rnti); + + // Fallback to connection establishment for unrecognized rntis, and PCIs that do not belong to eNB + if (old_ue_it == parent->users.end()) { + parent->logger.info( + "Fallback to connection establishment for rnti=0x%x. Cause: no rnti=0x%x context available", rnti, old_rnti); + srsran::console("Fallback to connection establishment for rnti=0x%x. Cause: no context available\n", rnti); + + // send RRC Setup + send_rrc_setup(); + set_activity_timeout(UE_INACTIVITY_TIMEOUT); + + return; + } + + // Reestablishment procedure going forward + parent->logger.info("ConnectionReestablishmentRequest for rnti=0x%x. Sending Connection Reestablishment.", old_rnti); + srsran::console("User 0x%x requesting RRC Reestablishment as 0x%x. Cause: %s\n", + rnti, + old_rnti, + msg.rrc_reest_request.reest_cause.to_string()); + + ue* old_ue = old_ue_it->second.get(); + + // Recover security setup + sec_ctx = old_ue->sec_ctx; + auto& pscell_cfg = parent->cfg.cell_list.at(UE_PSCELL_CC_IDX); + sec_ctx.regenerate_keys_handover(pscell_cfg.phy_cell.carrier.pci, pscell_cfg.dl_arfcn); + + // For the reestablishment, only add SRB1 to new UE context + next_radio_bearer_cfg.srb_to_add_mod_list_present = true; + next_radio_bearer_cfg.srb_to_add_mod_list.resize(1); + srb_to_add_mod_s& srb1 = next_radio_bearer_cfg.srb_to_add_mod_list[0]; + srb1.srb_id = 1; + + asn1::rrc_nr::radio_bearer_cfg_s dummy_radio_bearer_cfg; // just to compute difference, it's never sent to UE + compute_diff_radio_bearer_cfg(parent->cfg, radio_bearer_cfg, next_radio_bearer_cfg, dummy_radio_bearer_cfg); + + // - Setup masterCellGroup + // - Derive master cell group config bearers + fill_cellgroup_with_radio_bearer_cfg(parent->cfg, dummy_radio_bearer_cfg, next_cell_group_cfg); + + // send RRC Reestablishment message and restore bearer configuration + send_connection_reest(old_ue->sec_ctx.get_ncc()); + + // recover all previously created bearers from old UE object for (later) reconfiguration + next_radio_bearer_cfg = old_ue->radio_bearer_cfg; + next_cell_group_cfg = old_ue->cell_group_cfg; + + // Recover GTP-U tunnels and NGAP context + // parent->gtpu->mod_bearer_rnti(old_rnti, rnti); + parent->ngap->user_mod(old_rnti, rnti); + + // Reestablish E-RABs of old rnti later, during ConnectionReconfiguration + // bearer_list.reestablish_bearers(std::move(old_ue->bearer_list)); + + // remove old RNTI + // old_ue->mac_ctrl.set_drb_activation(false); + // parent->rem_user_thread(old_rnti); + + // state = RRC_STATE_WAIT_FOR_CON_REEST_COMPLETE; + set_activity_timeout(MSG5_RX_TIMEOUT); +} + +void rrc_nr::ue::send_connection_reest(uint8_t ncc) +{ + dl_dcch_msg_s msg; + rrc_reest_ies_s& reest = msg.msg.set_c1().set_rrc_reest().crit_exts.set_rrc_reest(); + + msg.msg.c1().rrc_reest().rrc_transaction_id = (uint8_t)((transaction_id++) % 4); + + // set NCC + reest.next_hop_chaining_count = ncc; + + // add PDCP bearers + update_pdcp_bearers(next_radio_bearer_cfg, next_cell_group_cfg); + + // add RLC bearers + update_rlc_bearers(next_cell_group_cfg); + + // add MAC bearers + update_mac(next_cell_group_cfg, false); + + if (send_dl_dcch(srsran::nr_srb::srb1, msg) != SRSRAN_SUCCESS) { + // TODO: Handle + } +} + /// TS 38.331, RRCReject message void rrc_nr::ue::send_rrc_reject(uint8_t reject_wait_time_secs) { @@ -913,7 +1037,6 @@ void rrc_nr::ue::send_rrc_setup() srb1.srb_id = 1; // Generate RRC setup message - dl_ccch_msg_s msg; rrc_setup_s& setup = msg.msg.set_c1().set_rrc_setup(); setup.rrc_transaction_id = (uint8_t)((transaction_id++) % 4); @@ -1208,6 +1331,22 @@ int rrc_nr::ue::update_pdcp_bearers(const asn1::rrc_nr::radio_bearer_cfg_s& radi return SRSRAN_ERROR; } parent->pdcp->add_bearer(rnti, rlc_bearer->lc_ch_id, pdcp_cnfg); + + // enable security config + if (sec_ctx.is_as_sec_cfg_valid()) { + srsran::nr_as_security_config_t tmp_cnfg = sec_ctx.get_as_sec_cfg(); + srsran::as_security_config_t pdcp_cnfg = {}; + pdcp_cnfg.k_rrc_int = tmp_cnfg.k_nr_rrc_int; + pdcp_cnfg.k_rrc_enc = tmp_cnfg.k_nr_rrc_enc; + pdcp_cnfg.k_up_int = tmp_cnfg.k_nr_up_int; + pdcp_cnfg.k_up_enc = tmp_cnfg.k_nr_up_enc; + pdcp_cnfg.integ_algo = (srsran::INTEGRITY_ALGORITHM_ID_ENUM)tmp_cnfg.integ_algo; + pdcp_cnfg.cipher_algo = (srsran::CIPHERING_ALGORITHM_ID_ENUM)tmp_cnfg.cipher_algo; + + // Setup SRB1 security/integrity. Encryption is set on completion + parent->pdcp->config_security(rnti, srb_to_lcid(srsran::nr_srb::srb1), pdcp_cnfg); + parent->pdcp->enable_integrity(rnti, srb_to_lcid(srsran::nr_srb::srb1)); + } } // Add DRBs