Check for mandatory Address registration tlv (ARMmbed#1853)

MTDs must include Address registration tlv in child id request.

Author: deepakvenugopal

source/6LoWPAN/Thread/thread_router_bootstrap.c

@@ -1665,6 +1665,11 @@ void thread_router_bootstrap_mle_receive_cb(int8_t interface_id, mle_message_t *
                         }
                     }
 
+                    if (!(id_req->mode & MLE_FFD_DEV) && addressRegisteredTlv.tlvLen == 0) {
+                        tr_debug("No address registration TLV in MTD child id request");
+                        thread_child_id_request_entry_remove(cur, id_req);
+                        return;
+                    }
 
                     id_req->keyId = security_headers->KeyIndex;
                     id_req->keySeq = common_read_32_bit(security_headers->Keysource);