Added support to PDCP SN len of 7. Also added a check for valid configs in pdcp entity.

lib/include/srslte/upper/pdcp_entity_lte.h

@@ -72,6 +72,9 @@ public:
     last_submitted_pdcp_rx_sn = last_submitted_pdcp_rx_sn_;
   }
 
+  // Config helpers
+  bool check_valid_config();
+
 private:
   srsue::rlc_interface_pdcp* rlc = nullptr;
   srsue::rrc_interface_pdcp* rrc = nullptr;

lib/src/asn1/rrc_asn1_utils.cc

@@ -214,26 +214,34 @@ srslte::pdcp_config_t make_drb_pdcp_config_t(const uint8_t bearer_id, bool is_ue
 
 srslte::pdcp_config_t make_drb_pdcp_config_t(const uint8_t bearer_id, bool is_ue, const asn1::rrc::pdcp_cfg_s& pdcp_cfg)
 {
-  pdcp_config_t cfg = make_drb_pdcp_config_t(bearer_id, is_ue);
-  // TODO: complete config processing
+  // TODO: complete config processing 
+  pdcp_discard_timer_t discard_timer =  pdcp_discard_timer_t::infinity;
   if (pdcp_cfg.discard_timer_present) {
     switch (pdcp_cfg.discard_timer.to_number()) {
       case 10:
-        cfg.discard_timer = pdcp_discard_timer_t::ms10;
+        discard_timer = pdcp_discard_timer_t::ms10;
         break;
       default:
-        cfg.discard_timer = pdcp_discard_timer_t::infinity;
+        discard_timer = pdcp_discard_timer_t::infinity;
         break;
     }
   }
 
+  pdcp_t_reordering_t t_reordering = pdcp_t_reordering_t::ms500;
   if (pdcp_cfg.t_reordering_r12_present) {
     switch (pdcp_cfg.t_reordering_r12.to_number()) {
       case 0:
-        cfg.t_reordering = pdcp_t_reordering_t::ms0;
+        t_reordering = pdcp_t_reordering_t::ms0;
         break;
       default:
-        cfg.t_reordering = pdcp_t_reordering_t::ms500;
+        t_reordering = pdcp_t_reordering_t::ms500;
+    }
+  }
+
+  uint8_t sn_len = srslte::PDCP_SN_LEN_12;
+  if (pdcp_cfg.rlc_um_present) {
+    if (pdcp_cfg.rlc_um.pdcp_sn_size.value == pdcp_cfg_s::rlc_um_s_::pdcp_sn_size_e_::len7bits) {
+      sn_len = srslte::PDCP_SN_LEN_7;
     }
   }
 
@@ -241,6 +249,13 @@ srslte::pdcp_config_t make_drb_pdcp_config_t(const uint8_t bearer_id, bool is_ue
     // TODO: handle RLC AM config for PDCP
   }
 
+  pdcp_config_t cfg(bearer_id,
+                    PDCP_RB_IS_DRB,
+                    is_ue ? SECURITY_DIRECTION_UPLINK : SECURITY_DIRECTION_DOWNLINK,
+                    is_ue ? SECURITY_DIRECTION_DOWNLINK : SECURITY_DIRECTION_UPLINK,
+                    sn_len,
+                    t_reordering,
+                    discard_timer);
   return cfg;
 }
 

lib/src/upper/pdcp_entity_base.cc

@@ -234,6 +234,9 @@ uint32_t pdcp_entity_base::read_data_header(const unique_byte_buffer_t& pdu)
     case PDCP_SN_LEN_5:
       rcvd_sn_32 = SN(pdu->msg[0]);
       break;
+    case PDCP_SN_LEN_7:
+      rcvd_sn_32 = SN(pdu->msg[0]);
+      break;
     case PDCP_SN_LEN_12:
       srslte::uint8_to_uint16(pdu->msg, &rcvd_sn_16);
       rcvd_sn_32 = SN(rcvd_sn_16);
@@ -270,6 +273,12 @@ void pdcp_entity_base::write_data_header(const srslte::unique_byte_buffer_t& sdu
     case PDCP_SN_LEN_5:
       sdu->msg[0] = SN(count); // Data PDU and SN LEN 5 implies SRB, D flag must not be present
       break;
+    case PDCP_SN_LEN_7:
+      sdu->msg[0] = SN(count); 
+      if (is_drb()) {
+        sdu->msg[0] |= 0x80; // On Data PDUs for DRBs we must set the D flag.
+      }
+      break;
     case PDCP_SN_LEN_12:
       srslte::uint16_to_uint8(SN(count), sdu->msg);
       if (is_drb()) {

lib/src/upper/pdcp_entity_lte.cc

@@ -66,6 +66,11 @@ void pdcp_entity_lte::init(uint32_t lcid_, pdcp_config_t cfg_)
             cfg.hdr_len_bytes,
             reordering_window,
             maximum_pdcp_sn);
+
+  // Check supported config
+  if (!check_valid_config()) {
+    log->console("Warning: Invalid PDCP config.\n");
+  }
 }
 
 // Reestablishment procedure: 36.323 5.2
@@ -323,7 +328,6 @@ void pdcp_entity_lte::handle_am_drb_pdu(srslte::unique_byte_buffer_t pdu)
 /****************************************************************************
  * Security functions
  ***************************************************************************/
-
 void pdcp_entity_lte::get_bearer_status(uint16_t* dlsn, uint16_t* dlhfn, uint16_t* ulsn, uint16_t* ulhfn)
 {
   if (cfg.rb_type == PDCP_RB_IS_DRB) {
@@ -342,4 +346,28 @@ void pdcp_entity_lte::get_bearer_status(uint16_t* dlsn, uint16_t* dlhfn, uint16_
   *ulhfn = (uint16_t)rx_hfn;
 }
 
+/****************************************************************************
+ * Config checking helper
+ ***************************************************************************/
+bool pdcp_entity_lte::check_valid_config()
+{
+  if (cfg.sn_len != PDCP_SN_LEN_5 && cfg.sn_len != PDCP_SN_LEN_7 && cfg.sn_len != PDCP_SN_LEN_12) {
+    log->error("Trying to configure bearer with invalid SN LEN=%d\n", cfg.sn_len);
+    return false;
+  }
+  if (cfg.sn_len == PDCP_SN_LEN_5 && is_drb()) {
+    log->error("Trying to configure DRB bearer with SN LEN of 5\n");
+    return false;
+  }
+  if (cfg.sn_len == PDCP_SN_LEN_7 && (is_srb() || !rlc->rb_is_um(lcid))) {
+    log->error("Trying to configure SRB or RLC AM bearer with SN LEN of 7\n");
+    return false;
+  }
+  if (cfg.sn_len == PDCP_SN_LEN_12 && is_srb()) {
+    log->error("Trying to configure SRB with SN LEN of 12.\n");
+    return false;
+  }
+  return true;
+}
+
 } // namespace srslte

srsenb/src/stack/rrc/rrc.cc

@@ -1895,20 +1895,14 @@ void rrc::ue::send_connection_reconf(srslte::unique_byte_buffer_t pdu)
         rnti, lcid, srslte::make_rlc_config_t(conn_reconf->rr_cfg_ded.drb_to_add_mod_list[vec_idx].rlc_cfg));
 
     // Configure DRB1 in PDCP
-    srslte::pdcp_config_t pdcp_cnfg_drb = srslte::make_drb_pdcp_config_t(drb_id, false);
-    if (conn_reconf->rr_cfg_ded.drb_to_add_mod_list[vec_idx].pdcp_cfg.rlc_um_present) {
-      if (conn_reconf->rr_cfg_ded.drb_to_add_mod_list[vec_idx].pdcp_cfg.rlc_um.pdcp_sn_size.value ==
-          pdcp_cfg_s::rlc_um_s_::pdcp_sn_size_e_::len7bits) {
-        pdcp_cnfg_drb.sn_len = srslte::PDCP_SN_LEN_7;
-      }
-    }
+    srslte::pdcp_config_t pdcp_cnfg_drb = srslte::make_drb_pdcp_config_t(drb_id, false, conn_reconf->rr_cfg_ded.drb_to_add_mod_list[vec_idx].pdcp_cfg);
     parent->pdcp->add_bearer(rnti, lcid, pdcp_cnfg_drb);
     parent->pdcp->config_security(rnti, lcid, sec_cfg);
     parent->pdcp->enable_integrity(rnti, lcid);
     parent->pdcp->enable_encryption(rnti, lcid);
 
     // DRBs have already been configured in GTPU through bearer setup
-    // Add E-RAB info message for E-RAB 5 (DRB1)
+    // Add E-RAB info message for the E-RABs
     std::map<uint8_t, srslte::unique_byte_buffer_t>::const_iterator it = erab_info_list.find(erab.id);
     if (it != erab_info_list.end()) {
       const srslte::unique_byte_buffer_t& erab_info = it->second;

srsue/src/stack/rrc/rrc.cc

@@ -2699,21 +2699,15 @@ void rrc::add_drb(drb_to_add_mod_s* drb_cnfg)
     rrc_log->warning("LCID not present, using %d\n", lcid);
   }
 
-  // Setup PDCP
-  pdcp_config_t pdcp_cfg = make_drb_pdcp_config_t(drb_cnfg->drb_id, true);
+  // Setup RLC
+  rlc->add_bearer(lcid, make_rlc_config_t(drb_cnfg->rlc_cfg));
 
-  if (drb_cnfg->pdcp_cfg.rlc_um_present) {
-    if (drb_cnfg->pdcp_cfg.rlc_um.pdcp_sn_size == pdcp_cfg_s::rlc_um_s_::pdcp_sn_size_e_::len7bits) {
-      pdcp_cfg.sn_len = 7;
-    }
-  }
+  // Setup PDCP
+  pdcp_config_t pdcp_cfg = make_drb_pdcp_config_t(drb_cnfg->drb_id, true, drb_cnfg->pdcp_cfg);
   pdcp->add_bearer(lcid, pdcp_cfg);
   pdcp->config_security(lcid, sec_cfg);
   pdcp->enable_encryption(lcid);
 
-  // Setup RLC
-  rlc->add_bearer(lcid, make_rlc_config_t(drb_cnfg->rlc_cfg));
-
   // Setup MAC
   uint8_t log_chan_group       = 0;
   uint8_t priority             = 1;