fix GTPU tunneling. Avoid forwarding packets to PDCP while the PDCP bearer is not yet created

lib/include/srslte/interfaces/enb_interfaces.h

@@ -478,6 +478,7 @@ public:
 
   virtual uint32_t
                add_bearer(uint16_t rnti, uint32_t lcid, uint32_t addr, uint32_t teid_out, const bearer_props* props = nullptr) = 0;
+  virtual void set_tunnel_status(uint32_t teidin, bool dl_active)    = 0;
   virtual void rem_bearer(uint16_t rnti, uint32_t lcid)              = 0;
   virtual void mod_bearer_rnti(uint16_t old_rnti, uint16_t new_rnti) = 0;
   virtual void rem_user(uint16_t rnti)                               = 0;

srsenb/hdr/stack/rrc/rrc_mobility.h

@@ -97,7 +97,9 @@ private:
 
     void enter(rrc_mobility* f, const ho_meas_report_ev& meas_report);
   };
-  struct s1_target_ho_st {};
+  struct s1_target_ho_st {
+    std::vector<uint32_t> pending_tunnels;
+  };
   struct wait_recfg_comp {};
   struct s1_source_ho_st : public subfsm_t<s1_source_ho_st> {
     struct ho_cmd_msg {
@@ -166,7 +168,7 @@ protected:
   // +----------------+-------------------+---------------------+----------------------------+-------------------------+
   row< idle_st,         s1_source_ho_st,   ho_meas_report_ev,   nullptr,                      &fsm::needs_s1_ho        >,
   row< idle_st,         intraenb_ho_st,    ho_meas_report_ev,   nullptr,                      &fsm::needs_intraenb_ho  >,
-  row< idle_st,         s1_target_ho_st,   ho_req_rx_ev,        &fsm::handle_ho_requested                                    >,
+  row< idle_st,         s1_target_ho_st,   ho_req_rx_ev,        &fsm::handle_ho_requested                              >,
   // +----------------+-------------------+---------------------+----------------------------+-------------------------+
   upd< intraenb_ho_st,                     user_crnti_upd_ev,   &fsm::handle_crnti_ce                                  >,
   row< intraenb_ho_st,  idle_st,           recfg_complete_ev,   &fsm::handle_recfg_complete                            >,

srsenb/hdr/stack/upper/gtpu.h

@@ -46,6 +46,7 @@ public:
                       uint32_t            addr,
                       uint32_t            teid_out,
                       const bearer_props* props = nullptr) override;
+  void     set_tunnel_status(uint32_t teidin, bool dl_active) override;
   void     rem_bearer(uint16_t rnti, uint32_t lcid) override;
   void     mod_bearer_rnti(uint16_t old_rnti, uint16_t new_rnti) override;
   void     rem_user(uint16_t rnti) override;
@@ -100,6 +101,7 @@ private:
   m1u_handler m1u;
 
   struct tunnel {
+    bool     dl_enabled            = true;
     bool     fwd_teid_in_present   = false;
     bool     prior_teid_in_present = false;
     uint16_t rnti                  = SRSLTE_INVALID_RNTI;

srsenb/src/stack/rrc/rrc_mobility.cc

@@ -75,7 +75,8 @@ uint16_t compute_mac_i(uint16_t                            crnti,
   }
   uint32_t N_bytes = bref.distance_bytes();
 
-  printf("Encoded varShortMAC: cellId=0x%x, PCI=%d, rnti=0x%x (%d bytes)", cellid, pci, crnti, N_bytes);
+  srslte::logmap::get("RRC")->info(
+      "Encoded varShortMAC: cellId=0x%x, PCI=%d, rnti=0x%x (%d bytes)", cellid, pci, crnti, N_bytes);
 
   // Compute MAC-I
   switch (integ_algo) {
@@ -731,6 +732,7 @@ void rrc::ue::rrc_mobility::handle_ho_requested(idle_st& s, const ho_req_rx_ev&
 
   // Set admitted E-RABs
   std::vector<asn1::s1ap::erab_admitted_item_s> admitted_erabs;
+  auto&                                         fwd_tunnels = get_state<s1_target_ho_st>()->pending_tunnels;
   for (auto& erab : rrc_ue->bearer_list.get_erabs()) {
     admitted_erabs.emplace_back();
     asn1::s1ap::erab_admitted_item_s& admitted_erab = admitted_erabs.back();
@@ -759,6 +761,7 @@ void rrc::ue::rrc_mobility::handle_ho_requested(idle_st& s, const ho_req_rx_ev&
         props.flush_before_teidin         = erab.second.teid_in;
         uint32_t dl_teid_in               = rrc_ue->bearer_list.add_gtpu_bearer(
             erab.second.id, erab.second.teid_out, erab.second.address.to_number(), &props);
+        fwd_tunnels.push_back(dl_teid_in);
         srslte::uint32_to_uint8(dl_teid_in, admitted_erabs.back().dl_g_tp_teid.data());
       }
     }
@@ -888,6 +891,11 @@ void rrc::ue::rrc_mobility::handle_status_transfer(s1_target_ho_st& s, const sta
     rrc_enb->pdcp->set_bearer_state(rrc_ue->rnti, drb_it->lc_ch_id, drb_state);
   }
 
+  // Enable forwarding of GTPU SDUs to PDCP
+  for (uint32_t teid : s.pending_tunnels) {
+    rrc_enb->gtpu->set_tunnel_status(teid, true);
+  }
+
   // Check if there is any pending Reconfiguration Complete. If there is, self-trigger
   if (pending_recfg_complete.crit_exts.type().value != rrc_conn_recfg_complete_s::crit_exts_c_::types_opts::nulltype) {
     trigger(pending_recfg_complete);

srsenb/src/stack/upper/gtpu.cc

@@ -160,7 +160,11 @@ uint32_t gtpu::add_bearer(uint16_t rnti, uint32_t lcid, uint32_t addr, uint32_t
 
   if (props != nullptr) {
     if (props->flush_before_teidin_present) {
+      // GTPU should wait for the bearer ctxt to arrive before sending SDUs from DL tunnel to PDCP
+      new_tun.dl_enabled = false;
+      // GTPU should not forward SDUs from main tunnel until the SeNB-TeNB tunnel has been flushed
       tunnel& after_tun               = tunnels.at(props->flush_before_teidin);
+      after_tun.dl_enabled            = false;
       after_tun.prior_teid_in_present = true;
       after_tun.prior_teid_in         = teid_in;
     }
@@ -177,6 +181,22 @@ uint32_t gtpu::add_bearer(uint16_t rnti, uint32_t lcid, uint32_t addr, uint32_t
   return teid_in;
 }
 
+void gtpu::set_tunnel_status(uint32_t teidin, bool dl_active)
+{
+  auto tun_it = tunnels.find(teidin);
+  if (tun_it == tunnels.end()) {
+    logger.warning("Setting TEID=%d status", teidin);
+    return;
+  }
+  tun_it->second.dl_enabled = dl_active;
+  if (dl_active) {
+    for (auto& sdu : tun_it->second.buffer) {
+      pdcp->write_sdu(tun_it->second.rnti, tun_it->second.lcid, std::move(sdu));
+    }
+    tun_it->second.buffer.clear();
+  }
+}
+
 void gtpu::rem_bearer(uint16_t rnti, uint32_t lcid)
 {
   auto ue_it = ue_teidin_db.find(rnti);
@@ -298,7 +318,7 @@ void gtpu::handle_gtpu_s1u_rx_packet(srslte::unique_byte_buffer_t pdu, const soc
       if (rx_tun.fwd_teid_in_present) {
         tunnel& tx_tun = tunnels.at(rx_tun.fwd_teid_in);
         send_pdu_to_tunnel(tx_tun, std::move(pdu));
-      } else if (rx_tun.prior_teid_in_present) {
+      } else if (not rx_tun.dl_enabled) {
         rx_tun.buffer.push_back(std::move(pdu));
       } else {
         uint32_t pdcp_sn = -1;
@@ -328,6 +348,7 @@ void gtpu::handle_gtpu_s1u_rx_packet(srslte::unique_byte_buffer_t pdu, const soc
             for (srslte::unique_byte_buffer_t& sdu : new_tun.buffer) {
               pdcp->write_sdu(new_tun.rnti, new_tun.lcid, std::move(sdu));
             }
+            new_tun.dl_enabled            = true;
             new_tun.prior_teid_in_present = false;
             new_tun.buffer.clear();
           }
@@ -501,7 +522,7 @@ void gtpu::log_message(tunnel& tun, bool is_rx, srslte::span<uint8_t> pdu, int p
   if (is_rx) {
     dir = "Rx";
     fmt::format_to(strbuf2, "{}:0x{:0x} > ", srslte::gtpu_ntoa(htonl(tun.spgw_addr)), tun.teid_in);
-    if (tun.prior_teid_in_present) {
+    if (not tun.dl_enabled) {
       fmt::format_to(strbuf2, "DL (buffered), ");
     } else if (tun.fwd_teid_in_present) {
       tunnel& tx_tun = tunnels.at(tun.fwd_teid_in);

srsenb/test/common/dummy_classes.h

@@ -139,6 +139,7 @@ public:
   {
     return 0;
   }
+  void set_tunnel_status(uint32_t teidin, bool dl_active) override {}
   void rem_bearer(uint16_t rnti, uint32_t lcid) override {}
   void mod_bearer_rnti(uint16_t old_rnti, uint16_t new_rnti) override {}
   void rem_user(uint16_t rnti) override {}