Refactor TUN Interface Management and Move to SDAP Layer

This commit refactors the TUN interface management by moving its creation
and configuration from the PDCP layer to the SDAP layer for UE.

Key changes include:

- Introduced `tun_generate_ue_ifname` and `tun_destroy` functions for better
  TUN interface lifecycle management.
- Added support for creating and destroying UE-specific TUN interfaces in SDAP.
- Refactored `nr_pdcp_module_init` to remove TUN-related logic and moved it
  to SDAP.
- Updated NAS and SDAP layers to handle PDU session-specific TUN interface
  creation and configuration.
- Enhanced SDAP entity management to include TUN socket handling and thread
  lifecycle.
- Updated NAS message handling to initialize default PDU session TUN
  interfaces in NOS1 mode.
- Use a single SDAP thread function for gNB and UE
- Allow noS1 mode also in SA on gNB

These changes improve modularity by isolating TUN interface management within
the SDAP layer, aligning with the 3GPP architecture, and simplifying the PDCP
layer.

Co-Authored-By: Robert Schmidt <robert.schmidt@openairinterface.org>

openair3/NAS/NR_UE/nr_nas_msg.c

@@ -64,6 +64,7 @@
 #include "secu_defs.h"
 #include "utils.h"
 #include "openair2/SDAP/nr_sdap/nr_sdap.h"
+#include "openair2/SDAP/nr_sdap/nr_sdap_entity.h"
 #include "fgs_nas_utils.h"
 #include "fgmm_service_accept.h"
 #include "fgmm_service_reject.h"
@@ -1059,7 +1060,7 @@ static int capture_ipv6_addr(const uint8_t *addr, char *ip, size_t len)
  * @brief Process PDU Session Address in PDU Session Establishment Accept message
  *        and configure the tun interface
  */
-static void process_pdu_session_addr(pdu_session_establishment_accept_msg_t *msg)
+static void process_pdu_session_addr(pdu_session_establishment_accept_msg_t *msg, int instance_id, int pdu_session_id)
 {
   uint8_t *addr = msg->pdu_addr_ie.pdu_addr_oct;
 
@@ -1067,18 +1068,13 @@ static void process_pdu_session_addr(pdu_session_establishment_accept_msg_t *msg
     case PDU_SESSION_TYPE_IPV4: {
       char ip[20];
       capture_ipv4_addr(&addr[0], ip, sizeof(ip));
-      char ifname[IFNAMSIZ];
-      tun_generate_ifname(ifname, "oaitun_ue", 0);
-      tun_config(ifname, ip, NULL);
-      setup_ue_ipv4_route(ifname, 0, ip);
+      create_ue_ip_if(ip, NULL, instance_id, pdu_session_id);
     } break;
 
     case PDU_SESSION_TYPE_IPV6: {
       char ipv6[40];
       capture_ipv6_addr(addr, ipv6, sizeof(ipv6));
-      char ifname[IFNAMSIZ];
-      tun_generate_ifname(ifname, "oaitun_ue", 0);
-      tun_config(ifname, NULL, ipv6);
+      create_ue_ip_if(NULL, ipv6, instance_id, pdu_session_id);
     } break;
 
     case PDU_SESSION_TYPE_IPV4V6: {
@@ -1086,10 +1082,7 @@ static void process_pdu_session_addr(pdu_session_establishment_accept_msg_t *msg
       capture_ipv6_addr(addr, ipv6, sizeof(ipv6));
       char ipv4[20];
       capture_ipv4_addr(&addr[IPv6_INTERFACE_ID_LENGTH], ipv4, sizeof(ipv4));
-      char ifname[IFNAMSIZ];
-      tun_generate_ifname(ifname, "oaitun_ue", 0);
-      tun_config(ifname, ipv4, ipv6);
-      setup_ue_ipv4_route(ifname, 0, ipv4);
+      create_ue_ip_if(ipv4, ipv6, instance_id, pdu_session_id);
     } break;
 
     default:
@@ -1101,7 +1094,7 @@ static void process_pdu_session_addr(pdu_session_establishment_accept_msg_t *msg
 /**
  * @brief Handle PDU Session Establishment Accept and process decoded message
  */
-static void handle_pdu_session_accept(uint8_t *pdu_buffer, uint32_t msg_length)
+static void handle_pdu_session_accept(uint8_t *pdu_buffer, uint32_t msg_length, int instance)
 {
   pdu_session_establishment_accept_msg_t msg = {0};
   int size = 0;
@@ -1143,24 +1136,23 @@ static void handle_pdu_session_accept(uint8_t *pdu_buffer, uint32_t msg_length)
     LOG_E(NAS, "decode_pdu_session_establishment_accept_msg failure\n");
 
   // process PDU Session
-
   if (msg.pdu_addr_ie.pdu_length)
-    process_pdu_session_addr(&msg);
+    process_pdu_session_addr(&msg, instance, sm_header.pdu_session_id);
   else
     LOG_W(NAS, "Optional PDU Address IE was not provided\n");
   
-  set_qfi_pduid(msg.qos_rules.rule->qfi, sm_header.pdu_session_id);
+  set_qfi(msg.qos_rules.rule->qfi, sm_header.pdu_session_id, instance);
 }
 
 /**
  * @brief Handle DL NAS Transport and process piggybacked 5GSM messages
  */
-static void handleDownlinkNASTransport(uint8_t *pdu_buffer, uint32_t msg_length)
+void handleDownlinkNASTransport(uint8_t * pdu_buffer, int pdu_length, int instance)
 {
   uint8_t msg_type = *(pdu_buffer + 16);
   if (msg_type == FGS_PDU_SESSION_ESTABLISHMENT_ACC) {
     LOG_A(NAS, "Received PDU Session Establishment Accept in DL NAS Transport\n");
-    handle_pdu_session_accept(pdu_buffer, msg_length);
+    handle_pdu_session_accept(pdu_buffer, pdu_length, instance);
   } else {
     LOG_E(NAS, "Received unexpected message in DLinformationTransfer %d\n", msg_type);
   }
@@ -1403,7 +1395,7 @@ static void send_nas_5gmm_ind(instance_t instance, const Guti5GSMobileIdentity_t
 static void request_default_pdusession(nr_ue_nas_t *nas)
 {
   MessageDef *message_p = itti_alloc_new_message(TASK_NAS_NRUE, nas->UE_id, NAS_PDU_SESSION_REQ);
-  NAS_PDU_SESSION_REQ(message_p).pdusession_id = 10; /* first or default pdu session */
+  NAS_PDU_SESSION_REQ(message_p).pdusession_id = get_softmodem_params()->default_pdu_session_id;
   NAS_PDU_SESSION_REQ(message_p).pdusession_type = 0x91; // 0x91 = IPv4, 0x92 = IPv6, 0x93 = IPv4v6
   NAS_PDU_SESSION_REQ(message_p).sst = nas->uicc->nssai_sst;
   NAS_PDU_SESSION_REQ(message_p).sd = nas->uicc->nssai_sd;
@@ -1634,7 +1626,7 @@ void *nas_nrue(void *args_p)
         if (msg_type == FGS_REGISTRATION_ACCEPT) {
           handle_registration_accept(nas, pdu_buffer, pdu_length);
         } else if (msg_type == FGS_PDU_SESSION_ESTABLISHMENT_ACC) {
-          handle_pdu_session_accept(pdu_buffer, pdu_length);
+          handle_pdu_session_accept(pdu_buffer, pdu_length, nas->UE_id);
         }
 
         // Free NAS buffer memory after use (coming from RRC)
@@ -1724,7 +1716,7 @@ void *nas_nrue(void *args_p)
             handle_security_mode_command(nas, &initialNasMsg, pdu_buffer, pdu_length);
             break;
           case FGS_DOWNLINK_NAS_TRANSPORT:
-            handleDownlinkNASTransport(pdu_buffer, pdu_length);
+            handleDownlinkNASTransport(pdu_buffer, pdu_length, nas->UE_id);
             break;
           case FGS_REGISTRATION_ACCEPT:
             handle_registration_accept(nas, pdu_buffer, pdu_length);
@@ -1735,7 +1727,7 @@ void *nas_nrue(void *args_p)
             nas->fiveGMM_state = FGS_DEREGISTERED;
             break;
           case FGS_PDU_SESSION_ESTABLISHMENT_ACC:
-            handle_pdu_session_accept(pdu_buffer, pdu_length);
+            handle_pdu_session_accept(pdu_buffer, pdu_length, nas->UE_id);
             break;
           case FGS_PDU_SESSION_ESTABLISHMENT_REJ:
             LOG_E(NAS, "Received PDU Session Establishment reject\n");
@@ -1767,6 +1759,15 @@ void *nas_nrue(void *args_p)
           send_nas_uplink_data_req(nas, &initialNasMsg);
       } break;
 
+      case NAS_INIT_NOS1_IF: {
+        const int pdu_session_id = get_softmodem_params()->default_pdu_session_id;
+        const char *ip = !get_softmodem_params()->nsa ? "10.0.1.2" : "10.0.1.3";
+        const int qfi = 7;
+        create_ue_ip_if(ip, NULL, nas->UE_id, pdu_session_id);
+        set_qfi(qfi, pdu_session_id, nas->UE_id);
+        break;
+      }
+
       default:
         LOG_E(NAS, "[UE %ld] Received unexpected message %s\n", nas->UE_id, ITTI_MSG_NAME(msg_p));
         break;

openair3/NAS/NR_UE/nr_nas_msg.h

@@ -110,5 +110,6 @@ void generateServiceRequest(as_nas_info_t *initialNasMsg, nr_ue_nas_t *nas);
 void *nas_nrue_task(void *args_p);
 void *nas_nrue(void *args_p);
 void nas_init_nrue(int num_ues);
+void nr_ue_create_ip_if(const char *ifnameprefix, const char *ipv4, const char *ipv6, int ue_id, int pdu_session_id);
 
 #endif /* __NR_NAS_MSG_SIM_H__*/