gtpu extension header added for downlink

src/common/3gpp_29.281.h

@@ -134,6 +134,7 @@ public:
   virtual ~gtpu_ie_value_exception() throw(){}
 };
 
+#define GTPU_NO_MORE_EXTENSION_HEADER                                        (0)
 #define GTPU_IE_RECOVERY                                                     14
 #define GTPU_IE_TUNNEL_ENDPOINT_IDENTIFIER_DATA_I                            16
 #define GTPU_IE_GTP_U_PEER_ADDRESS                                           133
@@ -147,6 +148,9 @@ public:
 #define GTPU_END_MARKER                                                     (254)
 #define GTPU_G_PDU                                                          (255)
 
+#define GTPU_DL_PDU_SESSION_INFORMATION                                     (0)
+#define GTPU_UL_PDU_SESSION_INFORMATION                                     (1)
+#define GTPU_PDU_SESSION_CONTAINER                                          (133)
 } // namespace
 
   // 8.2 Recovery

src/gtpv1u/gtpu.h

@@ -68,5 +68,21 @@ struct gtpuhdr
 
 
       /*The options start here. */
+  uint16_t sequence;
+  uint8_t pdu_number;
+  uint8_t next_ext_type;
    };
-#endif
+ #endif
+
+struct gtpu_ext_hdr{
+    struct gtpuhdr gtpu_hdr;
+    uint8_t message_length;
+    // PDU Type - This value indicates the structure of the PDU session UP frame. The field takes the value of the PDU
+    // Type it identifies; i.e. "0" for PDU Type 0. The PDU type is in bit 4 to bit 7 in the first octet of the frame.
+    uint8_t  pdu_type;
+    // QoS Flow Identifier (QFI): This parameter indicates the QoS Flow Identifier of the QoS flow to which
+    // the transferred packet bel
+    uint8_t qfi;
+    // Next Extension Header Type - This field defines the type of Extension Header that follows this field in the GTP-PDU
+    uint8_t next_ext_type;
+};

src/gtpv1u/gtpv1u.cpp

@@ -161,7 +161,7 @@ void gtpu_l4_stack::handle_receive_message_cb(
 void gtpu_l4_stack::send_g_pdu(
     const struct sockaddr_in& peer_addr, const teid_t teid, const char* payload,
     const ssize_t payload_len) {
-  struct gtpuhdr* gtpuhdr = reinterpret_cast<struct gtpuhdr*>(
+/*    struct gtpuhdr* gtpuhdr = reinterpret_cast<struct gtpuhdr*>(
       reinterpret_cast<uintptr_t>(payload) -
       (uintptr_t) sizeof(struct gtpuhdr));
   gtpuhdr->spare          = 0;
@@ -175,7 +175,36 @@ void gtpu_l4_stack::send_g_pdu(
   gtpuhdr->teid           = htobe32(teid);
   udp_s.async_send_to(
       reinterpret_cast<const char*>(gtpuhdr),
-      payload_len + sizeof(struct gtpuhdr), peer_addr);
+      payload_len + sizeof(struct gtpuhdr), peer_addr);*/
+  
+ // test this for multiple extension header
+   struct gtpu_ext_hdr* gtpu_ext_hdr = reinterpret_cast<struct gtpu_ext_hdr*>(
+     reinterpret_cast<uintptr_t>(payload) -
+       (uintptr_t) sizeof(struct gtpu_ext_hdr));
+  gtpu_ext_hdr->gtpu_hdr.spare          = 0;
+//  gtpuhdr->e              = 0;
+  gtpu_ext_hdr->gtpu_hdr.e              = 1;
+  gtpu_ext_hdr->gtpu_hdr.s              = 0;
+  gtpu_ext_hdr->gtpu_hdr.pn             = 0;
+  gtpu_ext_hdr->gtpu_hdr.pt             = 1;
+  gtpu_ext_hdr->gtpu_hdr.version        = 1;
+  gtpu_ext_hdr->gtpu_hdr.message_type   = GTPU_G_PDU;
+//  gtpuhdr->message_length = htobe16(payload_len);
+  gtpu_ext_hdr->gtpu_hdr.message_length = htobe16(payload_len + 8);
+  gtpu_ext_hdr->gtpu_hdr.teid           = htobe32(teid);
+
+  gtpu_ext_hdr->gtpu_hdr.pdu_number     = 0x00;
+  gtpu_ext_hdr->gtpu_hdr.sequence       = 0x00;
+  gtpu_ext_hdr->gtpu_hdr.next_ext_type  = GTPU_PDU_SESSION_CONTAINER;
+  gtpu_ext_hdr->message_length          = 0x01;
+  gtpu_ext_hdr->pdu_type                = GTPU_DL_PDU_SESSION_INFORMATION;
+  gtpu_ext_hdr->qfi                     = 0x06;
+  gtpu_ext_hdr->next_ext_type           = GTPU_NO_MORE_EXTENSION_HEADER;
+
+  udp_s.async_send_to(
+      reinterpret_cast<const char*>(gtpu_ext_hdr),
+//      payload_len + sizeof(struct gtpuhdr), peer_addr);
+      payload_len + sizeof(struct gtpu_ext_hdr), peer_addr);
 }
 //------------------------------------------------------------------------------
 void gtpu_l4_stack::send_g_pdu(