Check if RLC is suspended before transmiting PDCP SDU.

This was done to avoid integrity issues, when the UE's RRC erroneously sent
measurement reports while the re-establishment was already in progress.

As errously sending PDCP PDUs on DRBs can cause issues as well, this was
disabled too.

lib/include/srsran/interfaces/enb_rlc_interfaces.h

@@ -41,6 +41,7 @@ public:
   virtual void discard_sdu(uint16_t rnti, uint32_t lcid, uint32_t sn)                    = 0;
   virtual bool rb_is_um(uint16_t rnti, uint32_t lcid)                                    = 0;
   virtual bool sdu_queue_is_full(uint16_t rnti, uint32_t lcid)                           = 0;
+  virtual bool is_suspended(uint16_t rnti, uint32_t lcid)                                = 0;
 };
 
 // RLC interface for RRC
@@ -56,6 +57,7 @@ public:
   virtual void write_sdu(uint16_t rnti, uint32_t lcid, srsran::unique_byte_buffer_t sdu) = 0;
   virtual bool has_bearer(uint16_t rnti, uint32_t lcid)                                  = 0;
   virtual bool suspend_bearer(uint16_t rnti, uint32_t lcid)                              = 0;
+  virtual bool is_suspended(uint16_t rnti, uint32_t lcid)                                = 0;
   virtual bool resume_bearer(uint16_t rnti, uint32_t lcid)                               = 0;
   virtual void reestablish(uint16_t rnti)                                                = 0;
 };

lib/include/srsran/interfaces/ue_rlc_interfaces.h

@@ -51,6 +51,8 @@ public:
 
   ///< Allow PDCP to query SDU queue status
   virtual bool sdu_queue_is_full(uint32_t lcid) = 0;
+
+  virtual bool is_suspended(const uint32_t lcid) = 0;
 };
 
 class rlc_interface_mac : public srsran::read_pdu_interface

lib/src/pdcp/pdcp_entity_lte.cc

@@ -139,6 +139,11 @@ void pdcp_entity_lte::write_sdu(unique_byte_buffer_t sdu, int upper_sn)
     return;
   }
 
+  if (rlc->is_suspended(lcid)) {
+    logger.warning("Trying to send SDU while re-establishment is in progress. Dropping SDU. LCID=%d", lcid);
+    return;
+  }
+
   if (rlc->sdu_queue_is_full(lcid)) {
     logger.info(sdu->msg, sdu->N_bytes, "Dropping %s SDU due to full queue", rrc->get_rb_name(lcid));
     return;
@@ -166,7 +171,6 @@ void pdcp_entity_lte::write_sdu(unique_byte_buffer_t sdu, int upper_sn)
       return;
     }
   }
-
   // check for pending security config in transmit direction
   if (enable_security_tx_sn != -1 && enable_security_tx_sn == static_cast<int32_t>(tx_count)) {
     enable_integrity(DIRECTION_TX);

lib/test/pdcp/pdcp_base_test.h

@@ -55,6 +55,8 @@ public:
     logger.info("Discard_count=%" PRIu64 "", discard_count);
   }
 
+  bool is_suspended(uint32_t lcid) { return false; }
+
   uint64_t rx_count      = 0;
   uint64_t discard_count = 0;
 

srsenb/hdr/stack/upper/pdcp.h

@@ -77,6 +77,7 @@ private:
     void discard_sdu(uint32_t lcid, uint32_t discard_sn);
     bool rb_is_um(uint32_t lcid);
     bool sdu_queue_is_full(uint32_t lcid);
+    bool is_suspended(uint32_t lcid);
   };
 
   class user_interface_gtpu : public srsue::gw_interface_pdcp

srsenb/hdr/stack/upper/rlc.h

@@ -53,6 +53,7 @@ public:
   bool has_bearer(uint16_t rnti, uint32_t lcid);
   bool suspend_bearer(uint16_t rnti, uint32_t lcid);
   bool resume_bearer(uint16_t rnti, uint32_t lcid);
+  bool is_suspended(uint16_t rnti, uint32_t lcid);
   void reestablish(uint16_t rnti) final;
 
   // rlc_interface_pdcp

srsenb/src/stack/upper/pdcp.cc

@@ -217,6 +217,11 @@ bool pdcp::user_interface_rlc::rb_is_um(uint32_t lcid)
   return rlc->rb_is_um(rnti, lcid);
 }
 
+bool pdcp::user_interface_rlc::is_suspended(uint32_t lcid)
+{
+  return rlc->is_suspended(rnti, lcid);
+}
+
 bool pdcp::user_interface_rlc::sdu_queue_is_full(uint32_t lcid)
 {
   return rlc->sdu_queue_is_full(rnti, lcid);

srsenb/src/stack/upper/rlc.cc

@@ -150,6 +150,17 @@ bool rlc::suspend_bearer(uint16_t rnti, uint32_t lcid)
   return result;
 }
 
+bool rlc::is_suspended(uint16_t rnti, uint32_t lcid)
+{
+  pthread_rwlock_rdlock(&rwlock);
+  bool result = false;
+  if (users.count(rnti)) {
+    result = users[rnti].rlc->is_suspended(lcid);
+  }
+  pthread_rwlock_unlock(&rwlock);
+  return result;
+}
+
 bool rlc::resume_bearer(uint16_t rnti, uint32_t lcid)
 {
   pthread_rwlock_rdlock(&rwlock);

srsenb/test/common/dummy_classes_common.h

@@ -30,6 +30,7 @@ public:
   void write_sdu(uint16_t rnti, uint32_t lcid, srsran::unique_byte_buffer_t sdu) override { last_sdu = std::move(sdu); }
   bool has_bearer(uint16_t rnti, uint32_t lcid) override { return false; }
   bool suspend_bearer(uint16_t rnti, uint32_t lcid) override { return true; }
+  bool is_suspended(uint16_t rnti, uint32_t lcid) override { return false; }
   bool resume_bearer(uint16_t rnti, uint32_t lcid) override { return true; }
   void reestablish(uint16_t rnti) override {}
 

srsue/src/test/ttcn3/hdr/ttcn3_syssim.h

@@ -170,6 +170,8 @@ public:
 
   bool sdu_queue_is_full(uint32_t lcid);
 
+  bool is_suspended(uint32_t lcid);
+
   void set_as_security(const ttcn3_helpers::timing_info_t        timing,
                        const std::string                         cell_name,
                        std::array<uint8_t, 32>                   k_rrc_enc_,

srsue/src/test/ttcn3/src/ttcn3_syssim.cc

@@ -1191,6 +1191,11 @@ bool ttcn3_syssim::sdu_queue_is_full(uint32_t lcid)
   return false;
 }
 
+bool ttcn3_syssim::is_suspended(uint32_t lcid)
+{
+  return false;
+}
+
 void ttcn3_syssim::set_as_security(const ttcn3_helpers::timing_info_t        timing,
                                    const std::string                         cell_name,
                                    std::array<uint8_t, 32>                   k_rrc_enc_,