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authorChristian Grothoff <christian@grothoff.org>2019-04-21 14:49:26 +0200
committerChristian Grothoff <christian@grothoff.org>2019-04-21 14:49:26 +0200
commitfe3cc0e1a6f83c6ba4e0e1ec1185f1173ff16570 (patch)
treed3ab1e64f4e7643f059205e8dbf2cbc08295afbe
parent196435205b803f01976560037c69553ac0e8e307 (diff)
finish backchannel message delivery
-rw-r--r--src/transport/gnunet-service-tng.c412
-rw-r--r--src/transport/transport.h47
2 files changed, 415 insertions, 44 deletions
diff --git a/src/transport/gnunet-service-tng.c b/src/transport/gnunet-service-tng.c
index 56ba70b9a..4dc3a137d 100644
--- a/src/transport/gnunet-service-tng.c
+++ b/src/transport/gnunet-service-tng.c
@@ -24,8 +24,6 @@
*
* TODO:
* Implement next:
- * - complete backchannel signature verification and
- * forwarding of backchannel messages to communicators!
* - track RTT, distance, loss, etc. => requires extra data structures!
* - proper use/initialization of timestamps in messages exchanged
* during DV learning
@@ -153,6 +151,13 @@
GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 5)
/**
+ * How long do we cache backchannel (struct Backtalker) information
+ * after a backchannel goes inactive?
+ */
+#define BACKCHANNEL_INACTIVITY_TIMEOUT \
+ GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 5)
+
+/**
* How long before paths expire would we like to (re)discover DV paths? Should
* be below #DV_PATH_VALIDITY_TIMEOUT.
*/
@@ -289,7 +294,7 @@ struct TransportBackchannelEncapsulationMessage
/**
* Body by which a peer confirms that it is using an ephemeral key.
*/
-struct EphemeralConfirmation
+struct EphemeralConfirmationPS
{
/**
@@ -1965,6 +1970,65 @@ struct ValidationState
/**
+ * A Backtalker is a peer sending us backchannel messages. We use this
+ * struct to detect monotonic time violations, cache ephemeral key
+ * material (to avoid repeatedly checking signatures), and to synchronize
+ * monotonic time with the PEERSTORE.
+ */
+struct Backtalker
+{
+ /**
+ * Peer this is about.
+ */
+ struct GNUNET_PeerIdentity pid;
+
+ /**
+ * Last (valid) monotonic time received from this sender.
+ */
+ struct GNUNET_TIME_Absolute monotonic_time;
+
+ /**
+ * When will this entry time out?
+ */
+ struct GNUNET_TIME_Absolute timeout;
+
+ /**
+ * Last (valid) ephemeral key received from this sender.
+ */
+ struct GNUNET_CRYPTO_EcdhePublicKey last_ephemeral;
+
+ /**
+ * Task associated with this backtalker. Can be for timeout,
+ * or other asynchronous operations.
+ */
+ struct GNUNET_SCHEDULER_Task *task;
+
+ /**
+ * Communicator context waiting on this backchannel's @e get, or NULL.
+ */
+ struct CommunicatorMessageContext *cmc;
+
+ /**
+ * Handle for an operation to fetch @e monotonic_time information from the
+ * PEERSTORE, or NULL.
+ */
+ struct GNUNET_PEERSTORE_IterateContext *get;
+
+ /**
+ * Handle to a PEERSTORE store operation for this @e pid's @e
+ * monotonic_time. NULL if no PEERSTORE operation is pending.
+ */
+ struct GNUNET_PEERSTORE_StoreContext *sc;
+
+ /**
+ * Number of bytes of the original message body that follows after this
+ * struct.
+ */
+ size_t body_size;
+};
+
+
+/**
* Head of linked list of all clients to this service.
*/
static struct TransportClient *clients_head;
@@ -2001,6 +2065,12 @@ static struct GNUNET_CRYPTO_EddsaPrivateKey *GST_my_private_key;
static struct GNUNET_CONTAINER_MultiPeerMap *neighbours;
/**
+ * Map from PIDs to `struct Backtalker` entries. A peer is
+ * a backtalker if it recently send us backchannel messages.
+ */
+static struct GNUNET_CONTAINER_MultiPeerMap *backtalkers;
+
+/**
* Map from PIDs to `struct DistanceVector` entries describing
* known paths to the peer.
*/
@@ -3195,7 +3265,7 @@ lookup_ephemeral (const struct GNUNET_PeerIdentity *pid,
struct GNUNET_TIME_Absolute *ephemeral_validity)
{
struct EphemeralCacheEntry *ece;
- struct EphemeralConfirmation ec;
+ struct EphemeralConfirmationPS ec;
ece = GNUNET_CONTAINER_multipeermap_get (ephemeral_map, pid);
if ((NULL != ece) &&
@@ -4570,6 +4640,254 @@ check_backchannel_encapsulation (
/**
+ * We received the plaintext @a msg from backtalker @a b. Forward
+ * it to the respective communicator.
+ *
+ * @param b a backtalker
+ * @param msg a message, consisting of a `struct GNUNET_MessageHeader`
+ * followed by the target name of the communicator
+ * @param msg_size number of bytes in @a msg
+ */
+static void
+forward_backchannel_payload (struct Backtalker *b,
+ const void *msg,
+ size_t msg_size)
+{
+ struct GNUNET_TRANSPORT_CommunicatorBackchannelIncoming *cbi;
+ struct GNUNET_MQ_Envelope *env;
+ struct TransportClient *tc;
+ const struct GNUNET_MessageHeader *mh;
+ const char *target_communicator;
+ uint16_t mhs;
+
+ /* Determine target_communicator and check @a msg is well-formed */
+ mh = msg;
+ mhs = ntohs (mh->size);
+ if (mhs <= msg_size)
+ {
+ GNUNET_break_op (0);
+ return;
+ }
+ target_communicator = &((const char *) msg)[ntohs (mh->size)];
+ if ('\0' != target_communicator[msg_size - mhs - 1])
+ {
+ GNUNET_break_op (0);
+ return;
+ }
+ /* Find client providing this communicator */
+ for (tc = clients_head; NULL != tc; tc = tc->next)
+ if ((CT_COMMUNICATOR == tc->type) &&
+ (0 ==
+ strcmp (tc->details.communicator.address_prefix, target_communicator)))
+ break;
+ if (NULL == tc)
+ {
+ char *stastr;
+
+ GNUNET_asprintf (
+ &stastr,
+ "# Backchannel message dropped: target communicator `%s' unknown",
+ target_communicator);
+ GNUNET_STATISTICS_update (GST_stats, stastr, 1, GNUNET_NO);
+ GNUNET_free (stastr);
+ return;
+ }
+ /* Finally, deliver backchannel message to communicator */
+ env = GNUNET_MQ_msg_extra (
+ cbi,
+ msg_size,
+ GNUNET_MESSAGE_TYPE_TRANSPORT_COMMUNICATOR_BACKCHANNEL_INCOMING);
+ cbi->pid = b->pid;
+ memcpy (&cbi[1], msg, msg_size);
+ GNUNET_MQ_send (tc->mq, env);
+}
+
+
+/**
+ * Free data structures associated with @a b.
+ *
+ * @param b data structure to release
+ */
+static void
+free_backtalker (struct Backtalker *b)
+{
+ if (NULL != b->get)
+ {
+ GNUNET_PEERSTORE_iterate_cancel (b->get);
+ b->get = NULL;
+ GNUNET_assert (NULL != b->cmc);
+ finish_cmc_handling (b->cmc);
+ b->cmc = NULL;
+ }
+ if (NULL != b->task)
+ {
+ GNUNET_SCHEDULER_cancel (b->task);
+ b->task = NULL;
+ }
+ if (NULL != b->sc)
+ {
+ GNUNET_PEERSTORE_store_cancel (b->sc);
+ b->sc = NULL;
+ }
+ GNUNET_assert (
+ GNUNET_YES ==
+ GNUNET_CONTAINER_multipeermap_remove (backtalkers, &b->pid, b));
+ GNUNET_free (b);
+}
+
+
+/**
+ * Callback to free backtalker records.
+ *
+ * @param cls NULL
+ * @param pid unused
+ * @param value a `struct Backtalker`
+ * @return #GNUNET_OK (always)
+ */
+static int
+free_backtalker_cb (void *cls,
+ const struct GNUNET_PeerIdentity *pid,
+ void *value)
+{
+ struct Backtalker *b = value;
+
+ (void) cls;
+ (void) pid;
+ free_backtalker (b);
+ return GNUNET_OK;
+}
+
+
+/**
+ * Function called when it is time to clean up a backtalker.
+ *
+ * @param cls a `struct Backtalker`
+ */
+static void
+backtalker_timeout_cb (void *cls)
+{
+ struct Backtalker *b = cls;
+
+ b->task = NULL;
+ if (0 != GNUNET_TIME_absolute_get_remaining (b->timeout).rel_value_us)
+ {
+ b->task = GNUNET_SCHEDULER_add_at (b->timeout, &backtalker_timeout_cb, b);
+ return;
+ }
+ GNUNET_assert (NULL == b->sc);
+ free_backtalker (b);
+}
+
+
+/**
+ * Function called with the monotonic time of a backtalker
+ * by PEERSTORE. Updates the time and continues processing.
+ *
+ * @param cls a `struct Backtalker`
+ * @param record the information found, NULL for the last call
+ * @param emsg error message
+ */
+static void
+backtalker_monotime_cb (void *cls,
+ const struct GNUNET_PEERSTORE_Record *record,
+ const char *emsg)
+{
+ struct Backtalker *b = cls;
+ struct GNUNET_TIME_AbsoluteNBO *mtbe;
+ struct GNUNET_TIME_Absolute mt;
+
+ (void) emsg;
+ if (NULL == record)
+ {
+ /* we're done with #backtalker_monotime_cb() invocations,
+ continue normal processing */
+ b->get = NULL;
+ GNUNET_assert (NULL != b->cmc);
+ finish_cmc_handling (b->cmc);
+ b->cmc = NULL;
+ if (0 != b->body_size)
+ forward_backchannel_payload (b, &b[1], b->body_size);
+ return;
+ }
+ if (sizeof (*mtbe) != record->value_size)
+ {
+ GNUNET_break (0);
+ return;
+ }
+ mtbe = record->value;
+ mt = GNUNET_TIME_absolute_ntoh (*mtbe);
+ if (mt.abs_value_us > b->monotonic_time.abs_value_us)
+ {
+ GNUNET_STATISTICS_update (
+ GST_stats,
+ "# Backchannel messages dropped: monotonic time not increasing",
+ 1,
+ GNUNET_NO);
+ b->monotonic_time = mt;
+ /* Setting body_size to 0 prevents call to #forward_backchannel_payload() */
+ b->body_size = 0;
+ return;
+ }
+}
+
+
+/**
+ * Function called by PEERSTORE when the store operation of
+ * a backtalker's monotonic time is complete.
+ *
+ * @param cls the `struct Backtalker`
+ * @param success #GNUNET_OK on success
+ */
+static void
+backtalker_monotime_store_cb (void *cls, int success)
+{
+ struct Backtalker *b = cls;
+
+ if (GNUNET_OK != success)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ "Failed to store backtalker's monotonic time in PEERSTORE!\n");
+ }
+ b->sc = NULL;
+ b->task = GNUNET_SCHEDULER_add_at (b->timeout, &backtalker_timeout_cb, b);
+}
+
+
+/**
+ * The backtalker @a b monotonic time changed. Update PEERSTORE.
+ *
+ * @param b a backtalker with updated monotonic time
+ */
+static void
+update_backtalker_monotime (struct Backtalker *b)
+{
+ struct GNUNET_TIME_AbsoluteNBO mtbe;
+
+ if (NULL != b->sc)
+ {
+ GNUNET_PEERSTORE_store_cancel (b->sc);
+ b->sc = NULL;
+ }
+ else
+ {
+ GNUNET_SCHEDULER_cancel (b->task);
+ b->task = NULL;
+ }
+ mtbe = GNUNET_TIME_absolute_hton (b->monotonic_time);
+ b->sc = GNUNET_PEERSTORE_store (peerstore,
+ "transport",
+ &b->pid,
+ "transport-backchannel-monotonic-time",
+ &mtbe,
+ sizeof (mtbe),
+ GNUNET_TIME_UNIT_FOREVER_ABS,
+ GNUNET_PEERSTORE_STOREOPTION_REPLACE,
+ &backtalker_monotime_store_cb,
+ b);
+}
+
+
+/**
* Communicator gave us a backchannel encapsulation. Process the request.
* (We are not the origin of the backchannel here, the communicator simply
* received a backchannel message and we are expected to forward it.)
@@ -4611,6 +4929,8 @@ handle_backchannel_encapsulation (
}
/* begin actual decryption */
{
+ struct Backtalker *b;
+ struct GNUNET_TIME_Absolute monotime;
struct TransportBackchannelRequestPayload ppay;
char body[hdr_len - sizeof (ppay)];
@@ -4619,15 +4939,77 @@ handle_backchannel_encapsulation (
bc_decrypt (&key, &ppay, hdr, sizeof (ppay));
bc_decrypt (&key, &body, &hdr[sizeof (ppay)], hdr_len - sizeof (ppay));
bc_key_clean (&key);
- // FIXME: verify signatures in ppay!
- // => check if ephemeral key is known & valid, if not
- // => verify sig, cache ephemeral key
- // => update monotonic_time of sender for replay detection
-
- // FIXME: forward to specified communicator!
- // (using GNUNET_MESSAGE_TYPE_TRANSPORT_COMMUNICATOR_BACKCHANNEL_INCOMING)
+ monotime = GNUNET_TIME_absolute_ntoh (ppay.monotonic_time);
+ b = GNUNET_CONTAINER_multipeermap_get (backtalkers, &ppay.sender);
+ if ((NULL != b) && (monotime.abs_value_us < b->monotonic_time.abs_value_us))
+ {
+ GNUNET_STATISTICS_update (
+ GST_stats,
+ "# Backchannel messages dropped: monotonic time not increasing",
+ 1,
+ GNUNET_NO);
+ finish_cmc_handling (cmc);
+ return;
+ }
+ if ((NULL == b) ||
+ (0 != GNUNET_memcmp (&b->last_ephemeral, &be->ephemeral_key)))
+ {
+ /* Check signature */
+ struct EphemeralConfirmationPS ec;
+
+ ec.purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_TRANSPORT_EPHEMERAL);
+ ec.purpose.size = htonl (sizeof (ec));
+ ec.target = GST_my_identity;
+ ec.ephemeral_key = be->ephemeral_key;
+ if (
+ GNUNET_OK !=
+ GNUNET_CRYPTO_eddsa_verify (GNUNET_SIGNATURE_PURPOSE_TRANSPORT_EPHEMERAL,
+ &ec.purpose,
+ &ppay.sender_sig,
+ &ppay.sender.public_key))
+ {
+ /* Signature invalid, disard! */
+ GNUNET_break_op (0);
+ finish_cmc_handling (cmc);
+ return;
+ }
+ }
+ if (NULL != b)
+ {
+ /* update key cache and mono time */
+ b->last_ephemeral = be->ephemeral_key;
+ b->monotonic_time = monotime;
+ update_backtalker_monotime (b);
+ forward_backchannel_payload (b, body, sizeof (body));
+ b->timeout =
+ GNUNET_TIME_relative_to_absolute (BACKCHANNEL_INACTIVITY_TIMEOUT);
+ finish_cmc_handling (cmc);
+ return;
+ }
+ /* setup data structure to cache signature AND check
+ monotonic time with PEERSTORE before forwarding backchannel payload */
+ b = GNUNET_malloc (sizeof (struct Backtalker) + sizeof (body));
+ b->pid = ppay.sender;
+ b->body_size = sizeof (body);
+ memcpy (&b[1], body, sizeof (body));
+ GNUNET_assert (GNUNET_YES ==
+ GNUNET_CONTAINER_multipeermap_put (
+ backtalkers,
+ &b->pid,
+ b,
+ GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
+ b->monotonic_time = monotime; /* NOTE: to be checked still! */
+ b->cmc = cmc;
+ b->timeout =
+ GNUNET_TIME_relative_to_absolute (BACKCHANNEL_INACTIVITY_TIMEOUT);
+ b->task = GNUNET_SCHEDULER_add_at (b->timeout, &backtalker_timeout_cb, b);
+ b->get = GNUNET_PEERSTORE_iterate (peerstore,
+ "transport",
+ &b->pid,
+ "transport-backchannel-monotonic-time",
+ &backtalker_monotime_cb,
+ b);
}
- finish_cmc_handling (cmc);
}
@@ -7453,6 +7835,11 @@ do_shutdown (void *cls)
}
GNUNET_CONTAINER_multipeermap_destroy (neighbours);
neighbours = NULL;
+ GNUNET_CONTAINER_multipeermap_iterate (backtalkers,
+ &free_backtalker_cb,
+ NULL);
+ GNUNET_CONTAINER_multipeermap_destroy (backtalkers);
+ backtalkers = NULL;
GNUNET_CONTAINER_multipeermap_iterate (validation_map,
&free_validation_state_cb,
NULL);
@@ -7496,6 +7883,7 @@ run (void *cls,
(void) service;
/* setup globals */
GST_cfg = c;
+ backtalkers = GNUNET_CONTAINER_multipeermap_create (16, GNUNET_YES);
neighbours = GNUNET_CONTAINER_multipeermap_create (1024, GNUNET_YES);
dv_routes = GNUNET_CONTAINER_multipeermap_create (1024, GNUNET_YES);
ephemeral_map = GNUNET_CONTAINER_multipeermap_create (32, GNUNET_YES);
diff --git a/src/transport/transport.h b/src/transport/transport.h
index b9c61f306..d2a3a262b 100644
--- a/src/transport/transport.h
+++ b/src/transport/transport.h
@@ -54,12 +54,14 @@
/**
* Maximum frequency for re-evaluating latencies for all transport addresses.
*/
-#define LATENCY_EVALUATION_MAX_DELAY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 1)
+#define LATENCY_EVALUATION_MAX_DELAY \
+ GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 1)
/**
* Maximum frequency for re-evaluating latencies for connected addresses.
*/
-#define CONNECTED_LATENCY_EVALUATION_MAX_DELAY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 1)
+#define CONNECTED_LATENCY_EVALUATION_MAX_DELAY \
+ GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 1)
/**
* Similiar to GNUNET_TRANSPORT_NotifyDisconnect but in and out quotas are
@@ -71,11 +73,11 @@
* @param bandwidth_out outbound bandwidth in NBO
*
*/
-typedef void
-(*NotifyConnect) (void *cls,
- const struct GNUNET_PeerIdentity *peer,
- struct GNUNET_BANDWIDTH_Value32NBO bandwidth_in,
- struct GNUNET_BANDWIDTH_Value32NBO bandwidth_out);
+typedef void (*NotifyConnect) (
+ void *cls,
+ const struct GNUNET_PeerIdentity *peer,
+ struct GNUNET_BANDWIDTH_Value32NBO bandwidth_in,
+ struct GNUNET_BANDWIDTH_Value32NBO bandwidth_out);
GNUNET_NETWORK_STRUCT_BEGIN
@@ -106,7 +108,6 @@ struct StartMessage
* receiver should print out an error message and disconnect.
*/
struct GNUNET_PeerIdentity self;
-
};
@@ -155,7 +156,6 @@ struct DisconnectInfoMessage
* Who got disconnected?
*/
struct GNUNET_PeerIdentity peer;
-
};
@@ -181,7 +181,6 @@ struct QuotaSetMessage
* About which peer are we talking here?
*/
struct GNUNET_PeerIdentity peer;
-
};
@@ -201,7 +200,6 @@ struct InboundMessage
* Which peer sent the message?
*/
struct GNUNET_PeerIdentity peer;
-
};
@@ -240,7 +238,6 @@ struct SendOkMessage
* Which peer can send more now?
*/
struct GNUNET_PeerIdentity peer;
-
};
@@ -270,13 +267,11 @@ struct OutboundMessage
* Which peer should receive the message?
*/
struct GNUNET_PeerIdentity peer;
-
};
-
-
-#if !(defined(GNUNET_TRANSPORT_COMMUNICATION_VERSION)||defined(GNUNET_TRANSPORT_CORE_VERSION))
+#if ! (defined(GNUNET_TRANSPORT_COMMUNICATION_VERSION) || \
+ defined(GNUNET_TRANSPORT_CORE_VERSION))
/**
@@ -428,7 +423,6 @@ struct ValidationMonitorMessage
* The identity of the peer to look up.
*/
struct GNUNET_PeerIdentity peer;
-
};
@@ -452,7 +446,6 @@ struct PeerMonitorMessage
* The identity of the peer to look up.
*/
struct GNUNET_PeerIdentity peer;
-
};
@@ -545,7 +538,6 @@ struct PeerIterateResponseMessage
* Length of the plugin name
*/
uint32_t pluginlen GNUNET_PACKED;
-
};
@@ -572,7 +564,6 @@ struct BlacklistMessage
* Which peer is being blacklisted or queried?
*/
struct GNUNET_PeerIdentity peer;
-
};
@@ -644,7 +635,6 @@ struct TransportPluginMonitorMessage
/* followed by 0-terminated plugin name and
@e plugin_address_len bytes of plugin address */
-
};
#else
@@ -717,7 +707,6 @@ struct GNUNET_TRANSPORT_DelAddressMessage
* Address identifier.
*/
uint32_t aid GNUNET_PACKED;
-
};
@@ -783,7 +772,6 @@ struct GNUNET_TRANSPORT_IncomingMessageAck
* Sender identifier of the original message.
*/
struct GNUNET_PeerIdentity sender;
-
};
@@ -847,7 +835,6 @@ struct GNUNET_TRANSPORT_DelQueueMessage
* Receiver that can be addressed via the queue.
*/
struct GNUNET_PeerIdentity receiver;
-
};
@@ -883,7 +870,8 @@ struct GNUNET_TRANSPORT_CreateQueueResponse
{
/**
- * Type will be #GNUNET_MESSAGE_TYPE_TRANSPORT_QUEUE_CREATE_OK or #GNUNET_MESSAGE_TYPE_TRANSPORT_QUEUE_CREATE_FAIL.
+ * Type will be #GNUNET_MESSAGE_TYPE_TRANSPORT_QUEUE_CREATE_OK or
+ * #GNUNET_MESSAGE_TYPE_TRANSPORT_QUEUE_CREATE_FAIL.
*/
struct GNUNET_MessageHeader header;
@@ -949,7 +937,6 @@ struct GNUNET_TRANSPORT_SendMessageToAck
* Receiver identifier.
*/
struct GNUNET_PeerIdentity receiver;
-
};
@@ -990,7 +977,8 @@ struct GNUNET_TRANSPORT_CommunicatorBackchannel
struct GNUNET_TRANSPORT_CommunicatorBackchannelIncoming
{
/**
- * Type will be #GNUNET_MESSAGE_TYPE_TRANSPORT_COMMUNICATOR_BACKCHANNEL_INCOMING
+ * Type will be
+ * #GNUNET_MESSAGE_TYPE_TRANSPORT_COMMUNICATOR_BACKCHANNEL_INCOMING
*/
struct GNUNET_MessageHeader header;
@@ -1006,11 +994,9 @@ struct GNUNET_TRANSPORT_CommunicatorBackchannelIncoming
/* Followed by a `struct GNUNET_MessageHeader` with the encapsulated
message to the communicator */
-
};
-
/**
* Request to start monitoring.
*/
@@ -1031,7 +1017,6 @@ struct GNUNET_TRANSPORT_MonitorStart
* Target identifier to monitor, all zeros for "all peers".
*/
struct GNUNET_PeerIdentity peer;
-
};
@@ -1084,7 +1069,6 @@ struct GNUNET_TRANSPORT_MonitorData
uint32_t num_bytes_pending GNUNET_PACKED;
/* Followed by 0-terminated address of the peer */
-
};
@@ -1141,7 +1125,6 @@ struct ExpressPreferenceMessage
* How much bandwidth in bytes/second does the application expect?
*/
struct GNUNET_BANDWIDTH_Value32NBO bw;
-
};