git-svn-id: http://svn.eurecom.fr/openair4G/trunk@5957 818b1a75-f10b-46b9-bf7c-635c3b92a50f

openair-cn/GTPV1-U/nw-gtpv1u/src/NwGtpv1u.c

@@ -210,7 +210,7 @@ nwGtpv1uCreateAndSendMsg( NwGtpv1uStackT *thiz, NwU32T peerIp, NwU16T peerPort,
 
     *((NwU32T *) msgHdr) = htonl(pMsg->teid);
     msgHdr += 4;
-    GTPU_DEBUG("nwGtpv1uCreateAndSendMsg to teid %u\n", pMsg->teid);
+    GTPU_DEBUG("nwGtpv1uCreateAndSendMsg to teid %u length %d\n", pMsg->teid, pMsg->msgLen);
 
     if(pMsg->seqNumFlag || pMsg->extHdrFlag || pMsg->npduNumFlag) {
         *((NwU16T *) msgHdr) = (pMsg->seqNumFlag ? htons(pMsg->seqNum) : 0x0000);

openair-cn/GTPV1-U/nw-gtpv1u/src/NwGtpv1uMsg.c

@@ -121,6 +121,7 @@ nwGtpv1uGpduMsgNew( NW_IN NwGtpv1uStackHandleT hGtpuStackHandle,
 {
     NwGtpv1uStackT *pStack = (NwGtpv1uStackT *) hGtpuStackHandle;
     NwGtpv1uMsgT   *pMsg;
+    NwU32T          header_len = 0;
 
     if(gpGtpv1uMsgPool) {
         pMsg = gpGtpv1uMsgPool;
@@ -130,26 +131,57 @@ nwGtpv1uGpduMsgNew( NW_IN NwGtpv1uStackHandleT hGtpuStackHandle,
     }
 
     if(pMsg) {
+        // Version field: This field is used to determine the version of the GTP-U protocol.
+        // The version number shall be set to '1'.
         pMsg->version       = NW_GTPU_VERSION;
+        // Protocol Type (PT): This bit is used as a protocol discriminator between GTP (when PT is '1')
+        // and GTP' (when PT is '0'). GTP is described in this document and the GTP' protocol in 3GPP TS 32.295 [8].
+        // Note that the interpretation of the header fields may be different in GTP' than in GTP.
         pMsg->protocolType  = NW_GTP_PROTOCOL_TYPE_GTP;
+        // Extension Header flag (E): This flag indicates the presence of a meaningful value of the Next Extension
+        // Header field. When it is set to '0', the Next Extension Header field either is not present or, if present,
+        // shall not be interpreted.
         pMsg->extHdrFlag    = NW_FALSE;
+        // Sequence number flag (S): This flag indicates the presence of a meaningful value of the Sequence Number field.
+        // When it is set to '0', the Sequence Number field either is not present or, if present, shall not be interpreted.
+        // When it is set to '1', the Sequence Number field is present, and shall be interpreted, as described below in
+        // this section.
+        // For the Echo Request, Echo Response, Error Indication and Supported Extension Headers Notification
+        // messages, the S flag shall be set to '1'. Since the use of Sequence Numbers is optional for G-PDUs, the PGW,
+        // SGW, ePDG and eNodeB should set the flag to '0'. However, when a G-PDU (T-PDU+header) is being relayed
+        // by the Indirect Data Forwarding for Inter RAT HO procedure, then if the received G-PDU has the S flag set to
+        // '1', then the relaying entity shall set S flag to '1' and forward the G-PDU (T-PDU+header). In an End marker
+        // message the S flag shall be set to '0'.
         pMsg->seqNumFlag    = (seqNumFlag? NW_TRUE : NW_FALSE);
-        pMsg->npduNumFlag   = NW_FALSE;
-        pMsg->msgType       = NW_GTP_GPDU;
-        pMsg->teid          = teid;
         pMsg->seqNum        = seqNum;
+        // N-PDU Number flag (PN): This flag indicates the presence of a meaningful value of the N-PDU Number field.
+        // When it is set to '0', the N-PDU Number field either is not present, or, if present, shall not be interpreted.
+        // When it is set to '1', the N-PDU Number field is present, and shall be interpreted.
+        pMsg->npduNumFlag   = NW_FALSE;
         pMsg->npduNum       = 0x00;
-        pMsg->nextExtHdrType= 0x00;
+        // Message Type: This field indicates the type of GTP-U message.
+        pMsg->msgType       = NW_GTP_GPDU;
+        // Length: This field indicates the length in octets of the payload, i.e. the rest of the packet following the
+        // mandatory part of the GTP header (that is the first 8 octets).
+        // The Sequence Number, the N-PDU Number or any Extension headers shall be considered to be part of the payload,
+        // i.e. included in the length count.
+        header_len          = ((pMsg->seqNumFlag || pMsg->npduNumFlag || pMsg->extHdrFlag ) ?
+                                NW_GTPV1U_EPC_SPECIFIC_HEADER_SIZE : NW_GTPV1U_EPC_MIN_HEADER_SIZE);
         pMsg->msgLen        = ((pMsg->seqNumFlag || pMsg->npduNumFlag
                                 || pMsg->extHdrFlag ) ?
-                               NW_GTPV1U_EPC_SPECIFIC_HEADER_SIZE : (NW_GTPV1U_EPC_SPECIFIC_HEADER_SIZE - 4));
-
-        memcpy(pMsg->msgBuf + pMsg->msgLen, tpdu, tpduLength);
-        pMsg->msgLen        += tpduLength;
-        pMsg->msgLen        = pMsg->msgLen - ((pMsg->seqNumFlag || pMsg->npduNumFlag
-            || pMsg->extHdrFlag ) ?
-           NW_GTPV1U_EPC_SPECIFIC_HEADER_SIZE : (NW_GTPV1U_EPC_SPECIFIC_HEADER_SIZE - 4));
+                                (NW_GTPV1U_EPC_SPECIFIC_HEADER_SIZE - NW_GTPV1U_EPC_MIN_HEADER_SIZE) + tpduLength : tpduLength);
+
+        // Tunnel Endpoint Identifier (TEID): This field unambiguously identifies a tunnel endpoint in the receiving
+        // GTP-U protocol entity. The receiving end side of a GTP tunnel locally assigns the TEID value the transmitting
+        // side has to use. The TEID shall be used by the receiving entity to find the PDP context, except for the
+        // following cases:
+        // - The Echo Request/Response and Supported Extension Headers notification messages, where the Tunnel
+        //      Endpoint Identifier shall be set to all zeroes.
+        // - The Error Indication message where the Tunnel Endpoint Identifier shall be set to all zeros.
+        pMsg->teid          = teid;
+        pMsg->nextExtHdrType= 0x00;
 
+        memcpy(pMsg->msgBuf + header_len, tpdu, tpduLength);
         *phMsg = (NwGtpv1uMsgHandleT) pMsg;
         return NW_GTPV1U_OK;
     }