[IOT-2339] Add NULL check before variable access.

Added null check for 'sendData->remoteEndpoint' before the members
of remoteEndpoint gets accessed.

Change-Id: Ic4fc56087bcf9f72233f823ab5aaf0c39ec34afa
Signed-off-by: Senthil Kumar G S <senthil.gs@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/22271Tested-by: jenkins-iotivity <jenkins@iotivity.org>
Reviewed-by: Harish Marappa <h.marappa@samsung.com>
Reviewed-by: Ashok Babu Channa <ashok.channa@samsung.com>

resource/csdk/connectivity/src/cablockwisetransfer.c

@@ -944,7 +944,7 @@ CAResult_t CASetNextBlockOption1(coap_pdu_t *pdu, const CAEndpoint_t *endpoint,
             (CAToken_t)pdu->transport_hdr->udp.token,
             (uint8_t)pdu->transport_hdr->udp.token_length,
             endpoint->addr, endpoint->port);
-    if ((NULL == blockDataID) || (blockDataID->idLength < 1) || 
+    if ((NULL == blockDataID) || (blockDataID->idLength < 1) ||
         (blockDataID->idLength > UINT8_MAX))
     {
         OIC_LOG(ERROR, TAG, "blockId is incorrect");
@@ -2501,7 +2501,7 @@ CAResult_t CACheckBlockDataValidation(const CAData_t *sendData, CABlockData_t **
     VERIFY_NON_NULL(sendData, TAG, "sendData");
     VERIFY_NON_NULL(blockData, TAG, "blockData");
 
-    if (sendData->responseInfo)
+    if (sendData->responseInfo && sendData->remoteEndpoint)
     {
         CABlockDataID_t* blockDataID = CACreateBlockDatablockId(
                 (CAToken_t)sendData->responseInfo->info.token,