Handle IPv6/IPv4v6 PDU sessions

Handle IPv6 (and IPv4v6) PDU sessions by correctly instructing
nas_config() to set up the interface with provided IP addresses.
Note that as of now, IPv6 PDU sessions have not been fully tested.

Remove a useless assert at the gNB; to my understanding the gNB does not
care about the IP session type (at least for IP), as it just
transparently tunnels the IP packets from/to GTP.

I added a comment in the code where to change to request a PDU session
different from IPv4. Currently it is hardcoded to IPv4, and it seems
that a default OAI 5GC config would reject a PDU session type different
from IPv4.

openair2/RRC/NR/rrc_gNB_NGAP.c

@@ -310,7 +310,6 @@ static int decodePDUSessionResourceSetup(pdusession_t *session)
         /* mandatory PDUSessionType */
       case NGAP_ProtocolIE_ID_id_PDUSessionType:
         session->pdu_session_type = (uint8_t)pdusessionTransfer_ies->value.choice.PDUSessionType;
-        AssertFatal(session->pdu_session_type == PDUSessionType_ipv4 || session->pdu_session_type == PDUSessionType_ipv4v6, "To be developped: support not IPv4 sessions\n");
         break;
 
         /* optional SecurityIndication */

openair3/NAS/COMMON/ESM/MSG/PduSessionEstablishmentAccept.c

@@ -32,6 +32,29 @@ static uint16_t getShort(uint8_t *input)
   return htons(tmp16);
 }
 
+static int capture_ipv4_addr(const uint8_t *addr, char *ip, size_t len)
+{
+  return snprintf(ip, len, "%d.%d.%d.%d", addr[0], addr[1], addr[2], addr[3]);
+}
+
+static int capture_ipv6_addr(const uint8_t *addr, char *ip, size_t len)
+{
+  // 24.501 Sec 9.11.4.10: "an interface identifier for the IPv6 link local
+  // address": link local starts with fe80::, and only the last 64bits are
+  // given (middle is zero)
+  return snprintf(ip,
+                  len,
+                  "fe80::%02x%02x:%02x%02x:%02x%02x:%02x%02x",
+                  addr[0],
+                  addr[1],
+                  addr[2],
+                  addr[3],
+                  addr[4],
+                  addr[5],
+                  addr[6],
+                  addr[7]);
+}
+
 void capture_pdu_session_establishment_accept_msg(uint8_t *buffer, uint32_t msg_length)
 {
   security_protected_nas_5gs_msg_t       sec_nas_hdr;
@@ -103,25 +126,35 @@ void capture_pdu_session_establishment_accept_msg(uint8_t *buffer, uint32_t msg_
         psea_msg.pdu_addr_ie.pdu_length = *curPtr++;
         psea_msg.pdu_addr_ie.pdu_type = *curPtr++;
 
-        DevAssert(psea_msg.pdu_addr_ie.pdu_type == PDU_SESSION_TYPE_IPV4);
+        uint8_t *addr = psea_msg.pdu_addr_ie.pdu_addr_oct;
         if (psea_msg.pdu_addr_ie.pdu_type == PDU_SESSION_TYPE_IPV4) {
-          pdu_address_t *addr = &psea_msg.pdu_addr_ie;
-          addr->pdu_addr_oct1 = *curPtr++;
-          addr->pdu_addr_oct2 = *curPtr++;
-          addr->pdu_addr_oct3 = *curPtr++;
-          addr->pdu_addr_oct4 = *curPtr++;
+          for (int i = 0; i < 4; ++i)
+            addr[i] = *curPtr++;
           char ip[20];
-          snprintf(ip,
-                   sizeof(ip),
-                   "%d.%d.%d.%d",
-                   addr->pdu_addr_oct1,
-                   addr->pdu_addr_oct2,
-                   addr->pdu_addr_oct3,
-                   addr->pdu_addr_oct4);
+          capture_ipv4_addr(&addr[0], ip, sizeof(ip));
           nas_config(1, ip, NULL, "oaitun_ue");
           setup_ue_ipv4_route(1, ip, "oaitun_ue");
-          LOG_T(NAS, "PDU SESSION ESTABLISHMENT ACCEPT - Received UE IP: %s\n", ip);
+        } else if (psea_msg.pdu_addr_ie.pdu_type == PDU_SESSION_TYPE_IPV6) {
+          for (int i = 0; i < 8; ++i)
+            addr[i] = *curPtr++;
+          char ipv6[40];
+          capture_ipv6_addr(addr, ipv6, sizeof(ipv6));
+          nas_config(1, NULL, ipv6, "oaitun_ue");
+        } else if (psea_msg.pdu_addr_ie.pdu_type == PDU_SESSION_TYPE_IPV4V6) {
+          // 24.501 Sec 9.11.4.10: "If the PDU session type value indicates
+          // IPv4v6, the PDU address information in octet 4 to octet 11
+          // contains an interface identifier for the IPv6 link local address
+          // and in octet 12 to octet 15 contains an IPv4 address."
+          for (int i = 0; i < 12; ++i)
+            addr[i] = *curPtr++;
+          char ipv6[40];
+          capture_ipv6_addr(addr, ipv6, sizeof(ipv6));
+          char ipv4[20];
+          capture_ipv4_addr(&addr[8], ipv4, sizeof(ipv4));
+          nas_config(1, ipv4, ipv6, "oaitun_ue");
+          setup_ue_ipv4_route(1, ipv4, "oaitun_ue");
         } else {
+          LOG_E(NAS, "unknown/unhandled PDU session establishment accept PDU type %d\n", psea_msg.pdu_addr_ie.pdu_type);
           curPtr += psea_msg.pdu_addr_ie.pdu_length;
         }
         break;

openair3/NAS/COMMON/ESM/MSG/PduSessionEstablishmentAccept.h

@@ -114,10 +114,7 @@ typedef struct pdu_address_s {
   uint8_t pdu_iei;        /* PDU Address IEI (0x29) */
   uint8_t pdu_length;     /* Length of PDU address contents */
   uint8_t pdu_type;       /* PDU session type value */
-  uint8_t pdu_addr_oct1;  /* PDU address information (1st Octet)*/
-  uint8_t pdu_addr_oct2;  /* PDU address information (2nd Octet)*/
-  uint8_t pdu_addr_oct3;  /* PDU address information (3rd Octet)*/
-  uint8_t pdu_addr_oct4;  /* PDU address information (4th Octet)*/
+  uint8_t pdu_addr_oct[12];  /* PDU address information (depending on type, up to 12 bytes)*/
 } pdu_address_t; /* TS 24.501 9.11.4.10 */
 
 typedef struct dnn_s {

openair3/NAS/NR_UE/nr_nas_msg_sim.c

@@ -1176,7 +1176,7 @@ static void request_default_pdusession(int instance, int nssai_idx)
 {
   MessageDef *message_p = itti_alloc_new_message(TASK_NAS_NRUE, 0, 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_type = 0x91;
+  NAS_PDU_SESSION_REQ(message_p).pdusession_type = 0x91; // 0x91 = IPv4, 0x92 = IPv6, 0x93 = IPv4v6
   NAS_PDU_SESSION_REQ(message_p).sst = nas_allowed_nssai[nssai_idx].sst;
   NAS_PDU_SESSION_REQ(message_p).sd = nas_allowed_nssai[nssai_idx].sd;
   itti_send_msg_to_task(TASK_NAS_NRUE, instance, message_p);