nas,tft: add support for TFT modification

srsue/src/stack/upper/nas.cc

@@ -1625,13 +1625,25 @@ void nas::parse_modify_eps_bearer_context_request(srsran::unique_byte_buffer_t p
   ctxt.rx_count++;
 
   // check if bearer exists
-  if (eps_bearer.find(request.eps_bearer_id) == eps_bearer.end()) {
+  const auto it = eps_bearer.find(request.eps_bearer_id);
+  if (it == eps_bearer.end()) {
     logger.error("EPS bearer doesn't exist (eps_bearer_id=%d)", request.eps_bearer_id);
     // fixme: send proper response
     return;
   }
 
-  // fixme: carry out modification
+  LIBLTE_MME_TRAFFIC_FLOW_TEMPLATE_STRUCT* tft = &request.tft;
+  logger.info("Traffic Flow Template: TFT OP code 0x%x, Filter list size %d, Parameter list size %d",
+              tft->tft_op_code,
+              tft->packet_filter_list_size,
+              tft->parameter_list_size);
+
+  // modify/apply packet filters to GW
+  if (gw->apply_traffic_flow_template(request.eps_bearer_id, tft) != SRSRAN_SUCCESS) {
+    logger.error("Couldn't modify TFT");
+    return;
+  }
+
   logger.info("Modified EPS bearer context (eps_bearer_id=%d)", request.eps_bearer_id);
 
   send_modify_eps_bearer_context_accept(request.proc_transaction_id, request.eps_bearer_id);

srsue/src/stack/upper/tft_packet_filter.cc

@@ -415,6 +415,30 @@ int tft_pdu_matcher::apply_traffic_flow_template(const uint8_t&
         }
       }
       break;
+    case LIBLTE_MME_TFT_OPERATION_CODE_REPLACE_PACKET_FILTERS_IN_EXISTING_TFT:
+      for (int i = 0; i < tft->packet_filter_list_size; i++) {
+        // erase old filter if it exists
+        auto old_filter = std::find_if(
+            tft_filter_map.begin(), tft_filter_map.end(), [&](const std::pair<uint16_t, tft_packet_filter_t>& filter) {
+              return filter.second.id == tft->packet_filter_list[i].id;
+            });
+        if (old_filter == tft_filter_map.end()) {
+          logger.error("Error couldn't find TFT with id %d", tft->packet_filter_list[i].id);
+          return SRSRAN_ERROR_CANT_START;
+        }
+
+        // release old filter
+        tft_filter_map.erase(old_filter);
+
+        // Add new filter
+        tft_packet_filter_t new_filter(erab_id, tft->packet_filter_list[i], logger);
+        auto                it = tft_filter_map.insert(std::make_pair(new_filter.eval_precedence, new_filter));
+        if (it.second == false) {
+          logger.error("Error inserting TFT Packet Filter");
+          return SRSRAN_ERROR_CANT_START;
+        }
+      }
+      break;
     default:
       logger.error("Unhandled TFT OP code");
       return SRSRAN_ERROR_CANT_START;