gtpu,ngap: fix pdu session id check and lcid allocation

lib/include/srsran/common/common_nr.h

@@ -57,6 +57,15 @@ enum class nr_drb {
 const uint32_t MAX_NR_DRB_ID      = 29;
 const uint32_t MAX_NR_NOF_BEARERS = MAX_NR_DRB_ID + MAX_NR_SRB_ID; // 32
 
+// PDU Session ID range [1, 15]. See TS 24.007, 11.2.3.1b.
+const uint32_t MAX_NR_PDU_SESSION_ID = 15;
+const uint32_t MIN_NR_PDU_SESSION_ID = 1;
+
+constexpr bool is_nr_pdu_session_id(uint32_t pdu_session_id)
+{
+  return pdu_session_id >= MIN_NR_PDU_SESSION_ID and pdu_session_id <= MAX_NR_PDU_SESSION_ID;
+}
+
 constexpr bool is_nr_lcid(uint32_t lcid)
 {
   return lcid < MAX_NR_NOF_BEARERS;

srsenb/hdr/stack/upper/gtpu.h

@@ -49,7 +49,7 @@ class gtpu_tunnel_manager
 
 public:
   // A UE should have <= 3 DRBs active, and each DRB should have two tunnels active at the same time at most
-  const static size_t MAX_TUNNELS_PER_UE = 32;
+  const static size_t MAX_TUNNELS_PER_UE = 10;
 
   enum class tunnel_state { pdcp_active, buffering, forward_to, forwarded_from, inactive };
 

srsenb/src/stack/upper/gtpu.cc

@@ -65,8 +65,8 @@ gtpu_tunnel_manager::find_rnti_bearer_tunnels(uint16_t rnti, uint32_t eps_bearer
     logger.warning("Searching for bearer with invalid eps-BearerID=%d", eps_bearer_id);
     return {};
   }
-  if (ran_type == srsran::srsran_rat_t::nr and not is_nr_lcid(eps_bearer_id)) {
-    logger.warning("Searching for bearer with invalid eps-BearerID=%d", eps_bearer_id);
+  if (ran_type == srsran::srsran_rat_t::nr and not is_nr_pdu_session_id(eps_bearer_id)) {
+    logger.warning("Searching for bearer with invalid PDU Session Id=%d", eps_bearer_id);
     return {};
   }
   auto* ue_ptr = find_rnti_tunnels(rnti);
@@ -86,8 +86,8 @@ gtpu_tunnel_manager::add_tunnel(uint16_t rnti, uint32_t eps_bearer_id, uint32_t
     logger.warning("Adding TEID with invalid eps-BearerID=%d", eps_bearer_id);
     return nullptr;
   }
-  if (ran_type == srsran::srsran_rat_t::nr and not is_nr_lcid(eps_bearer_id)) {
-    logger.warning("Adding TEID with invalid eps-BearerID=%d", eps_bearer_id);
+  if (ran_type == srsran::srsran_rat_t::nr and not is_nr_pdu_session_id(eps_bearer_id)) {
+    logger.warning("Adding TEID with invalid PDU Session Id=%d", eps_bearer_id);
     return nullptr;
   }
   auto ret_pair = tunnels.insert(tunnel());

srsgnb/hdr/stack/ngap/ngap_ue_bearer_manager.h

@@ -64,8 +64,6 @@ private:
   pdu_session_list_t    pdu_session_list;
   srslog::basic_logger& logger;
 
-  std::map<uint32_t, uint32_t> next_lcid_list; // Map RNTI to next LCID to be allocated
-
   int     add_gtpu_bearer(uint16_t                                    rnti,
                           uint32_t                                    pdu_session_id,
                           uint32_t                                    teid_out,

srsgnb/src/stack/ngap/ngap_ue_bearer_manager.cc

@@ -11,6 +11,7 @@
  */
 
 #include "srsgnb/hdr/stack/ngap/ngap_ue_bearer_manager.h"
+#include "srsran/common/common_nr.h"
 
 namespace srsenb {
 ngap_ue_bearer_manager::ngap_ue_bearer_manager(gtpu_interface_rrc* gtpu_, srslog::basic_logger& logger_) :
@@ -39,6 +40,10 @@ int ngap_ue_bearer_manager::add_pdu_session(uint16_t
   }
 
   lcid = allocate_lcid(rnti);
+  if (lcid >= srsran::MAX_NR_NOF_BEARERS) {
+    logger.error("Adding PDU Session ID=%d to GTPU. No free LCID.", pdu_session_id);
+    return SRSRAN_ERROR;
+  }
 
   // TODO: remove lcid and just use pdu_session_id and rnti as id for GTP tunnel
   int rtn = add_gtpu_bearer(rnti, pdu_session_id, teid_out, addr_out, tunnel);
@@ -65,7 +70,6 @@ int ngap_ue_bearer_manager::reset_pdu_sessions(uint16_t rnti)
     auto pdu_session_id = iter->first;
     rem_gtpu_bearer(rnti, pdu_session_id);
   }
-  next_lcid_list.erase(rnti);
   return true;
 }
 
@@ -116,10 +120,20 @@ void ngap_ue_bearer_manager::rem_gtpu_bearer(uint16_t rnti, uint32_t pdu_session
 
 uint8_t ngap_ue_bearer_manager::allocate_lcid(uint32_t rnti)
 {
-  if (next_lcid_list.find(rnti) == next_lcid_list.end()) {
-    next_lcid_list[rnti] = 4;
+  if (pdu_session_list.empty()) {
+    return 4;
+  }
+  for (unsigned lcid = 4; lcid < srsran::MAX_NR_NOF_BEARERS; lcid++) {
+    const auto pdu_session_it =
+        std::find_if(pdu_session_list.cbegin(),
+                     pdu_session_list.cend(),
+                     [lcid](const std::pair<uint8_t, pdu_session_t>& t) { return t.second.lcid != lcid; });
+    if (pdu_session_it != pdu_session_list.cend()) {
+      return lcid;
+    }
   }
-  return next_lcid_list[rnti]++;
+  // All LCIDs are used.
+  return srsran::MAX_NR_NOF_BEARERS;
 }
 
 } // namespace srsenb