6 files changed, 260 insertions, 145 deletions

diff --git a/src/cadet/cadet_protocol.h b/src/cadet/cadet_protocol.h
index c45c4c684..2a0de2a8f 100644
--- a/src/cadet/cadet_protocol.h
+++ b/src/cadet/cadet_protocol.h
@@ -162,6 +162,23 @@ struct GNUNET_CADET_ConnectionDestroyMessage
 
 
 /**
+ * Unique identifier (counter) for an encrypted message in a channel.
+ * Used to match #GNUNET_MESSAGE_TYPE_CADET_ENCRYPTED_HOP_BY_HOP_ACK
+ * and  #GNUNET_MESSAGE_TYPE_CADET_CONNECTION_HOP_BY_HOP_POLL messages
+ * against the respective  #GNUNET_MESSAGE_TYPE_CONNECTION_ENCRYPTED
+ * messages.
+ */
+struct CadetEncryptedMessageIdentifier
+{
+  /**
+   * This number is incremented by one per message. It may wrap around.
+   * In network byte order.
+   */
+  uint32_t pid GNUNET_PACKED;
+};
+
+
+/**
  * Message to acknowledge cadet encrypted traffic.
  */
 struct GNUNET_CADET_ConnectionEncryptedAckMessage
@@ -174,7 +191,7 @@ struct GNUNET_CADET_ConnectionEncryptedAckMessage
   /**
    * Maximum packet ID authorized.
    */
-  uint32_t ack GNUNET_PACKED;
+  struct CadetEncryptedMessageIdentifier cemi;
 
   /**
    * ID of the connection.
@@ -196,7 +213,7 @@ struct GNUNET_CADET_ConnectionHopByHopPollMessage
   /**
    * Last packet sent.
    */
-  uint32_t pid GNUNET_PACKED;
+  struct CadetEncryptedMessageIdentifier cemi;
 
   /**
    * ID of the connection.
@@ -278,7 +295,7 @@ struct GNUNET_CADET_ConnectionEncryptedMessage
   /**
    * ID of the packet (hop by hop).
    */
-  uint32_t pid GNUNET_PACKED;
+  struct CadetEncryptedMessageIdentifier cemi;
 
   /**
    * ID of the connection.
@@ -404,7 +421,7 @@ struct GNUNET_CADET_ChannelDataMessage
 struct GNUNET_CADET_ChannelDataAckMessage
 {
   /**
-   * Type: GNUNET_MESSAGE_TYPE_CADET_CHANNEL_DATA_ACK
+   * Type: #GNUNET_MESSAGE_TYPE_CADET_CHANNEL_DATA_ACK
    */
   struct GNUNET_MessageHeader header;
 
diff --git a/src/cadet/gnunet-service-cadet_connection.c b/src/cadet/gnunet-service-cadet_connection.c
index 351bf2d3c..4eed0ec1c 100644
--- a/src/cadet/gnunet-service-cadet_connection.c
+++ b/src/cadet/gnunet-service-cadet_connection.c
@@ -112,17 +112,17 @@ struct CadetFlowControl
   /**
    * ID of the next packet to send.
    */
-  uint32_t next_pid;
+  struct CadetEncryptedMessageIdentifier next_pid;
 
   /**
    * ID of the last packet sent towards the peer.
    */
-  uint32_t last_pid_sent;
+  struct CadetEncryptedMessageIdentifier last_pid_sent;
 
   /**
    * ID of the last packet received from the peer.
    */
-  uint32_t last_pid_recv;
+  struct CadetEncryptedMessageIdentifier last_pid_recv;
 
   /**
    * Bitmap of past 32 messages received:
@@ -135,12 +135,12 @@ struct CadetFlowControl
    * Last ACK sent to the peer (peer is not allowed to send
    * messages with PIDs higher than this value).
    */
-  uint32_t last_ack_sent;
+  struct CadetEncryptedMessageIdentifier last_ack_sent;
 
   /**
    * Last ACK sent towards the origin (for traffic towards leaf node).
    */
-  uint32_t last_ack_recv;
+  struct CadetEncryptedMessageIdentifier last_ack_recv;
 
   /**
    * Task to poll the peer in case of a lost ACK causes stall.
@@ -359,7 +359,8 @@ static void
 fc_debug (struct CadetFlowControl *fc)
 {
   LOG (GNUNET_ERROR_TYPE_DEBUG, "    IN: %u/%u\n",
-              fc->last_pid_recv, fc->last_ack_sent);
+       ntohl (fc->last_pid_recv.pid),
+       ntohl (fc->last_ack_sent.pid));
   LOG (GNUNET_ERROR_TYPE_DEBUG, "    OUT: %u/%u\n",
               fc->last_pid_sent, fc->last_ack_recv);
   LOG (GNUNET_ERROR_TYPE_DEBUG, "    QUEUE: %u/%u\n",
@@ -453,11 +454,11 @@ GCC_state2s (enum CadetConnectionState s)
 static void
 fc_init (struct CadetFlowControl *fc)
 {
-  fc->next_pid = (uint32_t) 0;
-  fc->last_pid_sent = (uint32_t) -1;
-  fc->last_pid_recv = (uint32_t) -1;
-  fc->last_ack_sent = (uint32_t) 0;
-  fc->last_ack_recv = (uint32_t) 0;
+  fc->next_pid.pid = 0;
+  fc->last_pid_sent.pid = htonl (UINT32_MAX);
+  fc->last_pid_recv.pid = htonl (UINT32_MAX);
+  fc->last_ack_sent.pid = (uint32_t) 0;
+  fc->last_ack_recv.pid = (uint32_t) 0;
   fc->poll_task = NULL;
   fc->poll_time = GNUNET_TIME_UNIT_SECONDS;
   fc->queue_n = 0;
@@ -547,10 +548,11 @@ send_ack (struct CadetConnection *c,
           int fwd,
           int force)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   struct CadetFlowControl *next_fc;
   struct CadetFlowControl *prev_fc;
   struct GNUNET_CADET_ConnectionEncryptedAckMessage msg;
-  uint32_t ack;
+  struct CadetEncryptedMessageIdentifier ack_cemi;
   int delta;
 
   GCC_check_connections ();
@@ -563,24 +565,28 @@ send_ack (struct CadetConnection *c,
        GC_f2s (fwd), GCC_2s (c));
 
   /* Check if we need to transmit the ACK. */
-  delta = prev_fc->last_ack_sent - prev_fc->last_pid_recv;
+  delta = ntohl (prev_fc->last_ack_sent.pid) - ntohl (prev_fc->last_pid_recv.pid);
   if (3 < delta && buffer < delta && GNUNET_NO == force)
   {
     LOG (GNUNET_ERROR_TYPE_DEBUG, "Not sending ACK, delta > 3\n");
     LOG (GNUNET_ERROR_TYPE_DEBUG,
          "  last pid recv: %u, last ack sent: %u\n",
-         prev_fc->last_pid_recv, prev_fc->last_ack_sent);
+         ntohl (prev_fc->last_pid_recv.pid),
+         ntohl (prev_fc->last_ack_sent.pid));
     GCC_check_connections ();
     return;
   }
 
   /* Ok, ACK might be necessary, what PID to ACK? */
-  ack = prev_fc->last_pid_recv + buffer;
+  ack_cemi.pid = htonl (ntohl (prev_fc->last_pid_recv.pid) + buffer);
   LOG (GNUNET_ERROR_TYPE_DEBUG,
        " ACK %u, last PID %u, last ACK %u, qmax %u, q %u\n",
-       ack, prev_fc->last_pid_recv, prev_fc->last_ack_sent,
+       ntohl (ack_cemi.pid),
+       ntohl (prev_fc->last_pid_recv.pid),
+       ntohl (prev_fc->last_ack_sent.pid),
        next_fc->queue_max, next_fc->queue_n);
-  if (ack == prev_fc->last_ack_sent && GNUNET_NO == force)
+  if ( (ack_cemi.pid == prev_fc->last_ack_sent.pid) &&
+       (GNUNET_NO == force) )
   {
     LOG (GNUNET_ERROR_TYPE_DEBUG, "Not sending FWD ACK, not needed\n");
     GCC_check_connections ();
@@ -590,7 +596,8 @@ send_ack (struct CadetConnection *c,
   /* Check if message is already in queue */
   if (NULL != prev_fc->ack_msg)
   {
-    if (GC_is_pid_bigger (ack, prev_fc->last_ack_sent))
+    if (GC_is_pid_bigger (ntohl (ack_cemi.pid),
+                          ntohl (prev_fc->last_ack_sent.pid)))
     {
       LOG (GNUNET_ERROR_TYPE_DEBUG, " canceling old ACK\n");
       GCC_cancel (prev_fc->ack_msg);
@@ -603,20 +610,22 @@ send_ack (struct CadetConnection *c,
       return;
     }
   }
-  GNUNET_break (GC_is_pid_bigger (ack,
-                                  prev_fc->last_ack_sent));
-  prev_fc->last_ack_sent = ack;
+  GNUNET_break (GC_is_pid_bigger (ntohl (ack_cemi.pid),
+                                  ntohl (prev_fc->last_ack_sent.pid)));
+  prev_fc->last_ack_sent = ack_cemi;
 
   /* Build ACK message and send on conn */
   msg.header.size = htons (sizeof (msg));
   msg.header.type = htons (GNUNET_MESSAGE_TYPE_CADET_ENCRYPTED_HOP_BY_HOP_ACK);
-  msg.ack = htonl (ack);
+  msg.cemi = ack_cemi;
   msg.cid = c->id;
 
   prev_fc->ack_msg = GCC_send_prebuilt_message (&msg.header,
                                                 UINT16_MAX,
-                                                ack,
-                                                c, !fwd, GNUNET_YES,
+                                                zero,
+                                                c,
+                                                !fwd,
+                                                GNUNET_YES,
                                                 NULL, NULL);
   GNUNET_assert (NULL != prev_fc->ack_msg);
   GCC_check_connections ();
@@ -680,8 +689,12 @@ update_perf (struct CadetConnection *c,
  */
 static void
 conn_message_sent (void *cls,
-                   struct CadetConnection *c, int fwd, int sent,
-                   uint16_t type, uint16_t payload_type, uint32_t pid,
+                   struct CadetConnection *c,
+                   int fwd,
+                   int sent,
+                   uint16_t type,
+                   uint16_t payload_type,
+                   struct CadetEncryptedMessageIdentifier pid,
                    size_t size,
                    struct GNUNET_TIME_Relative wait)
 {
@@ -692,7 +705,10 @@ conn_message_sent (void *cls,
   GCC_check_connections ();
     LOG (GNUNET_ERROR_TYPE_INFO,
          ">>> %s (%s %4u) on conn %s (%p) %s [%5u] in queue %s\n",
-         GC_m2s (type), GC_m2s (payload_type), pid, GCC_2s (c), c,
+         GC_m2s (type), GC_m2s (payload_type),
+         ntohl (pid.pid),
+         GCC_2s (c),
+         c,
          GC_f2s (fwd), size,
          GNUNET_STRINGS_relative_time_to_string (wait, GNUNET_YES));
 
@@ -711,7 +727,8 @@ conn_message_sent (void *cls,
 
   LOG (GNUNET_ERROR_TYPE_DEBUG, " %ssent %s %s pid %u\n",
        sent ? "" : "not ", GC_f2s (fwd),
-       GC_m2s (type), GC_m2s (payload_type), pid);
+       GC_m2s (type), GC_m2s (payload_type),
+       ntohl (pid.pid));
   GCC_debug (c, GNUNET_ERROR_TYPE_DEBUG);
 
   /* Update flow control info. */
@@ -761,7 +778,8 @@ conn_message_sent (void *cls,
       if (GNUNET_YES == sent)
       {
         fc->last_pid_sent = pid;
-        if (GC_is_pid_bigger (fc->last_pid_sent + 1, fc->last_ack_recv))
+        if (GC_is_pid_bigger (ntohl (fc->last_pid_sent.pid) + 1,
+                              ntohl (fc->last_ack_recv.pid)) )
           GCC_start_poll (c, fwd);
         GCC_send_ack (c, fwd, GNUNET_NO);
         connection_reset_timeout (c, fwd);
@@ -772,14 +790,14 @@ conn_message_sent (void *cls,
       {
         fc->queue_n--;
         LOG (GNUNET_ERROR_TYPE_DEBUG,
-            "!   accounting pid %u\n",
-            fc->last_pid_sent);
+             "!   accounting pid %u\n",
+             ntohl (fc->last_pid_sent.pid));
       }
       else
       {
         LOG (GNUNET_ERROR_TYPE_DEBUG,
              "!   forced, Q_N not accounting pid %u\n",
-             fc->last_pid_sent);
+             ntohl (fc->last_pid_sent.pid));
       }
       break;
 
@@ -961,9 +979,11 @@ get_hop (struct CadetConnection *c, int fwd)
  * @param ooo_pid PID of the out-of-order message.
  */
 static uint32_t
-get_recv_bitmask (uint32_t last_pid_recv, uint32_t ooo_pid)
+get_recv_bitmask (struct CadetEncryptedMessageIdentifier last_pid_recv,
+                  struct CadetEncryptedMessageIdentifier ooo_pid)
 {
-  return 1 << (last_pid_recv - ooo_pid);
+  // FIXME: should assert that the delta is in range...
+  return 1 << (ntohl (last_pid_recv.pid) - ntohl (ooo_pid.pid));
 }
 
 
@@ -975,14 +995,18 @@ get_recv_bitmask (uint32_t last_pid_recv, uint32_t ooo_pid)
  * @param last_pid_recv Last in-order PID received.
  */
 static int
-is_ooo_ok (uint32_t last_pid_recv, uint32_t ooo_pid, uint32_t ooo_bitmap)
+is_ooo_ok (struct CadetEncryptedMessageIdentifier last_pid_recv,
+           struct CadetEncryptedMessageIdentifier ooo_pid,
+           uint32_t ooo_bitmap)
 {
   uint32_t mask;
 
-  if (GC_is_pid_bigger (last_pid_recv - 31, ooo_pid))
+  if (GC_is_pid_bigger (ntohl (last_pid_recv.pid) - 31,
+                        ntohl (ooo_pid.pid)))
     return GNUNET_NO;
 
-  mask = get_recv_bitmask (last_pid_recv, ooo_pid);
+  mask = get_recv_bitmask (last_pid_recv,
+                           ooo_pid);
   if (0 != (ooo_bitmap & mask))
     return GNUNET_NO;
 
@@ -1029,6 +1053,7 @@ is_fwd (const struct CadetConnection *c,
 static void
 send_connection_ack (struct CadetConnection *c, int fwd)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   struct GNUNET_CADET_ConnectionCreateMessageAckMessage msg;
   struct CadetTunnel *t;
   const uint16_t size = sizeof (struct GNUNET_CADET_ConnectionCreateMessageAckMessage);
@@ -1046,9 +1071,12 @@ send_connection_ack (struct CadetConnection *c, int fwd)
   msg.cid = c->id;
 
   GNUNET_assert (NULL == c->maintenance_q);
-  c->maintenance_q = GCP_send (get_hop (c, fwd), &msg.header,
-                               GNUNET_MESSAGE_TYPE_CADET_CONNECTION_CREATE_ACK, 0,
-                               c, fwd,
+  c->maintenance_q = GCP_send (get_hop (c, fwd),
+                               &msg.header,
+                               GNUNET_MESSAGE_TYPE_CADET_CONNECTION_CREATE_ACK,
+                               zero,
+                               c,
+                               fwd,
                                &conn_message_sent, NULL);
   LOG (GNUNET_ERROR_TYPE_DEBUG, "  C_P+ %p %u (conn`ACK)\n",
        c, c->pending_messages);
@@ -1076,6 +1104,7 @@ send_broken (struct CadetConnection *c,
              const struct GNUNET_PeerIdentity *id2,
              int fwd)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   struct GNUNET_CADET_ConnectionBrokenMessage msg;
 
   GCC_check_connections ();
@@ -1085,8 +1114,13 @@ send_broken (struct CadetConnection *c,
   msg.reserved = htonl (0);
   msg.peer1 = *id1;
   msg.peer2 = *id2;
-  (void) GCC_send_prebuilt_message (&msg.header, UINT16_MAX, 0, c, fwd,
-                                    GNUNET_YES, NULL, NULL);
+  (void) GCC_send_prebuilt_message (&msg.header,
+                                    UINT16_MAX,
+                                    zero,
+                                    c,
+                                    fwd,
+                                    GNUNET_YES,
+                                    NULL, NULL);
   GCC_check_connections ();
 }
 
@@ -1106,6 +1140,7 @@ send_broken_unknown (const struct GNUNET_CADET_ConnectionTunnelIdentifier *conne
                      const struct GNUNET_PeerIdentity *id2,
                      struct CadetPeer *neighbor)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   struct GNUNET_CADET_ConnectionBrokenMessage msg;
 
   GCC_check_connections ();
@@ -1121,9 +1156,12 @@ send_broken_unknown (const struct GNUNET_CADET_ConnectionTunnelIdentifier *conne
     msg.peer2 = *id2;
   else
     memset (&msg.peer2, 0, sizeof (msg.peer2));
-  GNUNET_assert (NULL != GCP_send (neighbor, &msg.header,
-                                   UINT16_MAX, 2,
-                                   NULL, GNUNET_SYSERR, /* connection, fwd */
+  GNUNET_assert (NULL != GCP_send (neighbor,
+                                   &msg.header,
+                                   UINT16_MAX,
+                                   zero,
+                                   NULL,
+                                   GNUNET_SYSERR, /* connection, fwd */
                                    NULL, NULL)); /* continuation */
   GCC_check_connections ();
 }
@@ -1418,6 +1456,7 @@ connection_cancel_queues (struct CadetConnection *c,
 static void
 send_poll (void *cls)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   struct CadetFlowControl *fc = cls;
   struct GNUNET_CADET_ConnectionHopByHopPollMessage msg;
   struct CadetConnection *c;
@@ -1433,11 +1472,17 @@ send_poll (void *cls)
   msg.header.type = htons (GNUNET_MESSAGE_TYPE_CADET_CONNECTION_HOP_BY_HOP_POLL);
   msg.header.size = htons (sizeof (msg));
   msg.cid = c->id;
-  msg.pid = htonl (fc->last_pid_sent);
-  LOG (GNUNET_ERROR_TYPE_DEBUG, " last pid sent: %u\n", fc->last_pid_sent);
-  fc->poll_msg =
-      GCC_send_prebuilt_message (&msg.header, UINT16_MAX, fc->last_pid_sent, c,
-                                 fc == &c->fwd_fc, GNUNET_YES, NULL, NULL);
+  msg.cemi = fc->last_pid_sent;
+  LOG (GNUNET_ERROR_TYPE_DEBUG, " last pid sent: %u\n", ntohl (fc->last_pid_sent.pid));
+  fc->poll_msg
+    = GCC_send_prebuilt_message (&msg.header,
+                                 UINT16_MAX,
+                                 zero,
+                                 c,
+                                 fc == &c->fwd_fc,
+                                 GNUNET_YES,
+                                 NULL,
+                                 NULL);
   GNUNET_assert (NULL != fc->poll_msg);
   GCC_check_connections ();
 }
@@ -1879,6 +1924,7 @@ void
 GCC_handle_create (struct CadetPeer *peer,
                    const struct GNUNET_CADET_ConnectionCreateMessage *msg)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   const struct GNUNET_CADET_ConnectionTunnelIdentifier *cid;
   struct GNUNET_PeerIdentity *id;
   struct CadetPeerPath *path;
@@ -2001,8 +2047,12 @@ GCC_handle_create (struct CadetPeer *peer,
     LOG (GNUNET_ERROR_TYPE_DEBUG, "  not for us, retransmitting...\n");
     GCP_add_path (dest_peer, path_duplicate (path), GNUNET_NO);
     GCP_add_path_to_origin (orig_peer, path_duplicate (path), GNUNET_NO);
-    (void) GCC_send_prebuilt_message (&msg->header, 0, 0, c,
-                                      GNUNET_YES, GNUNET_YES, NULL, NULL);
+    (void) GCC_send_prebuilt_message (&msg->header,
+                                      0,
+                                      zero,
+                                      c,
+                                      GNUNET_YES, GNUNET_YES,
+                                      NULL, NULL);
   }
   path_destroy (path);
   GCC_check_connections ();
@@ -2019,6 +2069,7 @@ void
 GCC_handle_confirm (struct CadetPeer *peer,
                     const struct GNUNET_CADET_ConnectionCreateMessageAckMessage *msg)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   struct CadetConnection *c;
   enum CadetConnectionState oldstate;
   int fwd;
@@ -2126,7 +2177,10 @@ GCC_handle_confirm (struct CadetPeer *peer,
   else
   {
     LOG (GNUNET_ERROR_TYPE_DEBUG, "  not for us, retransmitting...\n");
-    (void) GCC_send_prebuilt_message (&msg->header, 0, 0, c, fwd,
+    (void) GCC_send_prebuilt_message (&msg->header, 0,
+                                      zero,
+                                      c,
+                                      fwd,
                                       GNUNET_YES, NULL, NULL);
   }
   GCC_check_connections ();
@@ -2143,6 +2197,7 @@ void
 GCC_handle_broken (struct CadetPeer *peer,
                    const struct GNUNET_CADET_ConnectionBrokenMessage *msg)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   struct CadetConnection *c;
   struct CadetTunnel *t;
   int fwd;
@@ -2195,7 +2250,8 @@ GCC_handle_broken (struct CadetPeer *peer,
   }
   else
   {
-    (void) GCC_send_prebuilt_message (&msg->header, 0, 0, c, fwd,
+    (void) GCC_send_prebuilt_message (&msg->header, 0,
+                                      zero, c, fwd,
                                       GNUNET_YES, NULL, NULL);
     connection_cancel_queues (c, !fwd);
   }
@@ -2214,6 +2270,7 @@ void
 GCC_handle_destroy (struct CadetPeer *peer,
                     const struct GNUNET_CADET_ConnectionDestroyMessage *msg)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   struct CadetConnection *c;
   int fwd;
 
@@ -2245,7 +2302,8 @@ GCC_handle_destroy (struct CadetPeer *peer,
 
   if (GNUNET_NO == GCC_is_terminal (c, fwd))
   {
-    (void) GCC_send_prebuilt_message (&msg->header, 0, 0, c, fwd,
+    (void) GCC_send_prebuilt_message (&msg->header, 0,
+                                      zero, c, fwd,
                                       GNUNET_YES, NULL, NULL);
   }
   else if (0 == c->pending_messages)
@@ -2278,7 +2336,7 @@ GCC_handle_ack (struct CadetPeer *peer,
 {
   struct CadetConnection *c;
   struct CadetFlowControl *fc;
-  uint32_t ack;
+  struct CadetEncryptedMessageIdentifier ack;
   int fwd;
 
   GCC_check_connections ();
@@ -2315,15 +2373,19 @@ GCC_handle_ack (struct CadetPeer *peer,
     return;
   }
 
-  ack = ntohl (msg->ack);
+  ack = msg->cemi;
   LOG (GNUNET_ERROR_TYPE_DEBUG, " %s ACK %u (was %u)\n",
-       GC_f2s (fwd), ack, fc->last_ack_recv);
-  if (GC_is_pid_bigger (ack, fc->last_ack_recv))
+       GC_f2s (fwd),
+       ntohl (ack.pid),
+       ntohl (fc->last_ack_recv.pid));
+  if (GC_is_pid_bigger (ntohl (ack.pid),
+                        ntohl (fc->last_ack_recv.pid)))
     fc->last_ack_recv = ack;
 
   /* Cancel polling if the ACK is big enough. */
   if ( (NULL != fc->poll_task) &
-       GC_is_pid_bigger (fc->last_ack_recv, fc->last_pid_sent))
+       GC_is_pid_bigger (ntohl (fc->last_ack_recv.pid),
+                         ntohl (fc->last_pid_sent.pid)))
   {
     LOG (GNUNET_ERROR_TYPE_DEBUG, "  Cancel poll\n");
     GNUNET_SCHEDULER_cancel (fc->poll_task);
@@ -2347,7 +2409,7 @@ GCC_handle_poll (struct CadetPeer *peer,
 {
   struct CadetConnection *c;
   struct CadetFlowControl *fc;
-  uint32_t pid;
+  struct CadetEncryptedMessageIdentifier pid;
   int fwd;
 
   GCC_check_connections ();
@@ -2389,8 +2451,11 @@ GCC_handle_poll (struct CadetPeer *peer,
     return;
   }
 
-  pid = ntohl (msg->pid);
-  LOG (GNUNET_ERROR_TYPE_DEBUG, "  PID %u, OLD %u\n", pid, fc->last_pid_recv);
+  pid = msg->cemi;
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "  PID %u, OLD %u\n",
+       ntohl (pid.pid),
+       ntohl (fc->last_pid_recv.pid));
   fc->last_pid_recv = pid;
   fwd = fc == &c->bck_fc;
   GCC_send_ack (c, fwd, GNUNET_YES);
@@ -2417,7 +2482,7 @@ check_message (const struct GNUNET_MessageHeader *message,
                const struct GNUNET_CADET_ConnectionTunnelIdentifier* cid,
                struct CadetConnection *c,
                struct CadetPeer *sender,
-               uint32_t pid)
+               struct CadetEncryptedMessageIdentifier pid)
 {
   struct CadetFlowControl *fc;
   struct CadetPeer *hop;
@@ -2470,10 +2535,11 @@ check_message (const struct GNUNET_MessageHeader *message,
   {
     fc = fwd ? &c->bck_fc : &c->fwd_fc;
     LOG (GNUNET_ERROR_TYPE_DEBUG, " PID %u (expected in interval [%u,%u])\n",
-         pid,
-         fc->last_pid_recv + 1,
-         fc->last_ack_sent);
-    if (GC_is_pid_bigger (pid, fc->last_ack_sent))
+         ntohl (pid.pid),
+         ntohl (fc->last_pid_recv.pid) + 1,
+         ntohl (fc->last_ack_sent.pid));
+    if (GC_is_pid_bigger (ntohl (pid.pid),
+                          ntohl (fc->last_ack_sent.pid)))
     {
       GNUNET_STATISTICS_update (stats,
                                 "# unsolicited message",
@@ -2484,11 +2550,12 @@ check_message (const struct GNUNET_MessageHeader *message,
            pid, fc->last_pid_recv, fc->last_ack_sent);
       return GNUNET_SYSERR;
     }
-    if (GC_is_pid_bigger (pid, fc->last_pid_recv))
+    if (GC_is_pid_bigger (ntohl (pid.pid),
+                          ntohl (fc->last_pid_recv.pid)))
     {
       unsigned int delta;
 
-      delta = pid - fc->last_pid_recv;
+      delta = ntohl (pid.pid) - ntohl (fc->last_pid_recv.pid);
       fc->last_pid_recv = pid;
       fc->recv_bitmap <<= delta;
       fc->recv_bitmap |= 1;
@@ -2505,10 +2572,12 @@ check_message (const struct GNUNET_MessageHeader *message,
       {
         LOG (GNUNET_ERROR_TYPE_WARNING,
              "PID %u unexpected (%u+), dropping!\n",
-             pid, fc->last_pid_recv - 31);
+             ntohl (pid.pid),
+             ntohl (fc->last_pid_recv.pid) - 31);
         return GNUNET_SYSERR;
       }
-      fc->recv_bitmap |= get_recv_bitmask (fc->last_pid_recv, pid);
+      fc->recv_bitmap |= get_recv_bitmask (fc->last_pid_recv,
+                                           pid);
     }
   }
 
@@ -2539,6 +2608,7 @@ void
 GCC_handle_kx (struct CadetPeer *peer,
                const struct GNUNET_CADET_TunnelKeyExchangeMessage *msg)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   const struct GNUNET_CADET_ConnectionTunnelIdentifier* cid;
   struct CadetConnection *c;
   int fwd;
@@ -2552,7 +2622,7 @@ GCC_handle_kx (struct CadetPeer *peer,
                        cid,
                        c,
                        peer,
-                       0);
+                       zero);
 
   /* If something went wrong, discard message. */
   if (GNUNET_SYSERR == fwd)
@@ -2580,7 +2650,8 @@ GCC_handle_kx (struct CadetPeer *peer,
   /* Message not for us: forward to next hop */
   LOG (GNUNET_ERROR_TYPE_DEBUG, "  not for us, retransmitting...\n");
   GNUNET_STATISTICS_update (stats, "# messages forwarded", 1, GNUNET_NO);
-  (void) GCC_send_prebuilt_message (&msg->header, 0, 0, c, fwd,
+  (void) GCC_send_prebuilt_message (&msg->header, 0,
+                                    zero, c, fwd,
                                     GNUNET_NO, NULL, NULL);
   GCC_check_connections ();
 }
@@ -2596,14 +2667,15 @@ void
 GCC_handle_encrypted (struct CadetPeer *peer,
                       const struct GNUNET_CADET_ConnectionEncryptedMessage *msg)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   const struct GNUNET_CADET_ConnectionTunnelIdentifier* cid;
   struct CadetConnection *c;
-  uint32_t pid;
+  struct CadetEncryptedMessageIdentifier pid;
   int fwd;
 
   GCC_check_connections ();
   cid = &msg->cid;
-  pid = ntohl (msg->pid);
+  pid = msg->cemi;
   log_message (&msg->header, peer, cid);
 
   c = connection_get (cid);
@@ -2639,7 +2711,8 @@ GCC_handle_encrypted (struct CadetPeer *peer,
   /* Message not for us: forward to next hop */
   LOG (GNUNET_ERROR_TYPE_DEBUG, "  not for us, retransmitting...\n");
   GNUNET_STATISTICS_update (stats, "# messages forwarded", 1, GNUNET_NO);
-  (void) GCC_send_prebuilt_message (&msg->header, 0, 0, c, fwd,
+  (void) GCC_send_prebuilt_message (&msg->header, 0,
+                                    zero, c, fwd,
                                     GNUNET_NO, NULL, NULL);
   GCC_check_connections ();
 }
@@ -2966,12 +3039,12 @@ GCC_get_allowed (struct CadetConnection *c, int fwd)
 
   fc = fwd ? &c->fwd_fc : &c->bck_fc;
   if ( (CADET_CONNECTION_READY != c->state) ||
-       GC_is_pid_bigger (fc->last_pid_recv,
-                         fc->last_ack_sent) )
+       GC_is_pid_bigger (ntohl (fc->last_pid_recv.pid),
+                         ntohl (fc->last_ack_sent.pid)) )
   {
     return 0;
   }
-  return (fc->last_ack_sent - fc->last_pid_recv);
+  return (ntohl (fc->last_ack_sent.pid) - ntohl (fc->last_pid_recv.pid));
 }
 
 
@@ -2999,18 +3072,17 @@ GCC_get_qn (struct CadetConnection *c, int fwd)
  *
  * @param c Connection.
  * @param fwd Is query about FWD traffic?
- *
  * @return Next PID to use.
  */
-uint32_t
+struct CadetEncryptedMessageIdentifier
 GCC_get_pid (struct CadetConnection *c, int fwd)
 {
   struct CadetFlowControl *fc;
-  uint32_t pid;
+  struct CadetEncryptedMessageIdentifier pid;
 
   fc = fwd ? &c->fwd_fc : &c->bck_fc;
   pid = fc->next_pid;
-  fc->next_pid++;
+  fc->next_pid.pid = htonl (1 + ntohl (pid.pid));
   return pid;
 }
 
@@ -3155,8 +3227,10 @@ GCC_is_sendable (struct CadetConnection *c, int fwd)
   fc = fwd ? &c->fwd_fc : &c->bck_fc;
   LOG (GNUNET_ERROR_TYPE_DEBUG,
        " last ack recv: %u, last pid sent: %u\n",
-       fc->last_ack_recv, fc->last_pid_sent);
-  if (GC_is_pid_bigger (fc->last_ack_recv, fc->last_pid_sent))
+       ntohl (fc->last_ack_recv.pid),
+       ntohl (fc->last_pid_sent.pid));
+  if (GC_is_pid_bigger (ntohl (fc->last_ack_recv.pid),
+                        ntohl (fc->last_pid_sent.pid)))
   {
     LOG (GNUNET_ERROR_TYPE_DEBUG, " sendable\n");
     return GNUNET_YES;
@@ -3201,7 +3275,8 @@ GCC_is_direct (struct CadetConnection *c)
  */
 struct CadetConnectionQueue *
 GCC_send_prebuilt_message (const struct GNUNET_MessageHeader *message,
-                           uint16_t payload_type, uint32_t payload_id,
+                           uint16_t payload_type,
+                           struct CadetEncryptedMessageIdentifier payload_id,
                            struct CadetConnection *c, int fwd, int force,
                            GCC_sent cont, void *cont_cls)
 {
@@ -3229,7 +3304,10 @@ GCC_send_prebuilt_message (const struct GNUNET_MessageHeader *message,
   {
     case GNUNET_MESSAGE_TYPE_CONNECTION_ENCRYPTED:
       LOG (GNUNET_ERROR_TYPE_DEBUG, "  Q_N+ %p %u, PIDsnt: %u, ACKrcv: %u\n",
-            fc, fc->queue_n, fc->last_pid_sent, fc->last_ack_recv);
+           fc,
+           fc->queue_n,
+           ntohl (fc->last_pid_sent.pid),
+           ntohl (fc->last_ack_recv.pid));
       if (GNUNET_NO == force)
       {
         fc->queue_n++;
@@ -3281,9 +3359,12 @@ GCC_send_prebuilt_message (const struct GNUNET_MessageHeader *message,
   q->cont_cls = cont_cls;
   q->forced = force;
   GNUNET_CONTAINER_DLL_insert (fc->q_head, fc->q_tail, q);
-  q->peer_q = GCP_send (get_hop (c, fwd), message,
-                        payload_type, payload_id,
-                        c, fwd,
+  q->peer_q = GCP_send (get_hop (c, fwd),
+                        message,
+                        payload_type,
+                        payload_id,
+                        c,
+                        fwd,
                         &conn_message_sent, q);
   if (NULL == q->peer_q)
   {
@@ -3327,6 +3408,7 @@ GCC_cancel (struct CadetConnectionQueue *q)
 void
 GCC_send_create (struct CadetConnection *c)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   enum CadetTunnelCState state;
   size_t size;
 
@@ -3339,6 +3421,7 @@ GCC_send_create (struct CadetConnection *c)
     struct GNUNET_CADET_ConnectionCreateMessage *msg;
     struct GNUNET_PeerIdentity *peers;
 
+
     msg = (struct GNUNET_CADET_ConnectionCreateMessage *) cbuf;
     msg->header.size = htons (size);
     msg->header.type = htons (GNUNET_MESSAGE_TYPE_CADET_CONNECTION_CREATE);
@@ -3352,7 +3435,8 @@ GCC_send_create (struct CadetConnection *c)
     GNUNET_assert (NULL == c->maintenance_q);
     c->maintenance_q = GCP_send (get_next_hop (c),
                                  &msg->header,
-                                 GNUNET_MESSAGE_TYPE_CADET_CONNECTION_CREATE, 0,
+                                 GNUNET_MESSAGE_TYPE_CADET_CONNECTION_CREATE,
+                                 zero,
                                  c, GNUNET_YES,
                                  &conn_message_sent, NULL);
   }
@@ -3449,6 +3533,7 @@ GCC_send_ack (struct CadetConnection *c, int fwd, int force)
 void
 GCC_send_destroy (struct CadetConnection *c)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   struct GNUNET_CADET_ConnectionDestroyMessage msg;
 
   if (GNUNET_YES == c->destroy)
@@ -3463,10 +3548,16 @@ GCC_send_destroy (struct CadetConnection *c)
               GCC_2s (c));
 
   if (GNUNET_NO == GCC_is_terminal (c, GNUNET_YES))
-    (void) GCC_send_prebuilt_message (&msg.header, UINT16_MAX, 0, c,
+    (void) GCC_send_prebuilt_message (&msg.header,
+                                      UINT16_MAX,
+                                      zero,
+                                      c,
                                       GNUNET_YES, GNUNET_YES, NULL, NULL);
   if (GNUNET_NO == GCC_is_terminal (c, GNUNET_NO))
-    (void) GCC_send_prebuilt_message (&msg.header, UINT16_MAX, 0, c,
+    (void) GCC_send_prebuilt_message (&msg.header,
+                                      UINT16_MAX,
+                                      zero,
+                                      c,
                                       GNUNET_NO, GNUNET_YES, NULL, NULL);
   mark_destroyed (c);
   GCC_check_connections ();
@@ -3597,9 +3688,11 @@ GCC_debug (const struct CadetConnection *c, enum GNUNET_ErrorType level)
   LOG2 (level, "CCC  FWD flow control:\n");
   LOG2 (level, "CCC   queue: %u/%u\n", c->fwd_fc.queue_n, c->fwd_fc.queue_max);
   LOG2 (level, "CCC   last PID sent: %5u, recv: %5u\n",
-        c->fwd_fc.last_pid_sent, c->fwd_fc.last_pid_recv);
+        ntohl (c->fwd_fc.last_pid_sent.pid),
+        ntohl (c->fwd_fc.last_pid_recv.pid));
   LOG2 (level, "CCC   last ACK sent: %5u, recv: %5u\n",
-        c->fwd_fc.last_ack_sent, c->fwd_fc.last_ack_recv);
+        ntohl (c->fwd_fc.last_ack_sent.pid),
+        ntohl (c->fwd_fc.last_ack_recv.pid));
   LOG2 (level, "CCC   recv PID bitmap: %X\n", c->fwd_fc.recv_bitmap);
   LOG2 (level, "CCC   poll: task %d, msg  %p, msg_ack %p)\n",
         c->fwd_fc.poll_task, c->fwd_fc.poll_msg, c->fwd_fc.ack_msg);
@@ -3607,9 +3700,11 @@ GCC_debug (const struct CadetConnection *c, enum GNUNET_ErrorType level)
   LOG2 (level, "CCC  BCK flow control:\n");
   LOG2 (level, "CCC   queue: %u/%u\n", c->bck_fc.queue_n, c->bck_fc.queue_max);
   LOG2 (level, "CCC   last PID sent: %5u, recv: %5u\n",
-        c->bck_fc.last_pid_sent, c->bck_fc.last_pid_recv);
+        ntohl (c->bck_fc.last_pid_sent.pid),
+        ntohl (c->bck_fc.last_pid_recv.pid));
   LOG2 (level, "CCC   last ACK sent: %5u, recv: %5u\n",
-        c->bck_fc.last_ack_sent, c->bck_fc.last_ack_recv);
+        ntohl (c->bck_fc.last_ack_sent.pid),
+        ntohl (c->bck_fc.last_ack_recv.pid));
   LOG2 (level, "CCC   recv PID bitmap: %X\n", c->bck_fc.recv_bitmap);
   LOG2 (level, "CCC   poll: task %d, msg  %p, msg_ack %p)\n",
         c->bck_fc.poll_task, c->bck_fc.poll_msg, c->bck_fc.ack_msg);
diff --git a/src/cadet/gnunet-service-cadet_connection.h b/src/cadet/gnunet-service-cadet_connection.h
index 6df307dd1..ab2920ba3 100644
--- a/src/cadet/gnunet-service-cadet_connection.h
+++ b/src/cadet/gnunet-service-cadet_connection.h
@@ -372,10 +372,9 @@ GCC_get_qn (struct CadetConnection *c, int fwd);
  *
  * @param c Connection.
  * @param fwd Is query about FWD traffic?
- *
  * @return Next PID to use.
  */
-uint32_t
+struct CadetEncryptedMessageIdentifier
 GCC_get_pid (struct CadetConnection *c, int fwd);
 
 /**
@@ -497,7 +496,8 @@ GCC_cancel (struct CadetConnectionQueue *q);
  */
 struct CadetConnectionQueue *
 GCC_send_prebuilt_message (const struct GNUNET_MessageHeader *message,
-                           uint16_t payload_type, uint32_t payload_id,
+                           uint16_t payload_type,
+                           struct CadetEncryptedMessageIdentifier payload_id,
                            struct CadetConnection *c, int fwd, int force,
                            GCC_sent cont, void *cont_cls);
 
diff --git a/src/cadet/gnunet-service-cadet_peer.c b/src/cadet/gnunet-service-cadet_peer.c
index 2c2c552c6..2b11040a5 100644
--- a/src/cadet/gnunet-service-cadet_peer.c
+++ b/src/cadet/gnunet-service-cadet_peer.c
@@ -103,9 +103,9 @@ struct CadetPeerQueue {
     uint16_t payload_type;
 
     /**
-     *ID of the payload (PID, ACK #, ...).
+     * ID of the payload (PID, ACK #, ...).
      */
-    uint16_t payload_id;
+    struct CadetEncryptedMessageIdentifier payload_id;
 
     /**
      * Connection this message was sent on.
@@ -1110,7 +1110,9 @@ call_peer_cont (struct CadetPeerQueue *q, int sent)
              GNUNET_STRINGS_relative_time_to_string (wait_time, GNUNET_NO));
         q->cont (q->cont_cls,
                  q->c, q->c_fwd, sent,
-                 q->type, q->payload_type, q->payload_id,
+                 q->type,
+                 q->payload_type,
+                 q->payload_id,
                  q->size, wait_time);
         q->cont = NULL;
     }
@@ -1173,7 +1175,7 @@ struct CadetPeerQueue *
 GCP_send (struct CadetPeer *peer,
           const struct GNUNET_MessageHeader *message,
           uint16_t payload_type,
-          uint32_t payload_id,
+          struct CadetEncryptedMessageIdentifier payload_id,
           struct CadetConnection *c,
           int fwd,
           GCP_sent cont,
@@ -1188,7 +1190,8 @@ GCP_send (struct CadetPeer *peer,
     size = ntohs (message->size);
     LOG (GNUNET_ERROR_TYPE_DEBUG,
          "que %s (%s %4u) on conn %s (%p) %s towards %s (size %u)\n",
-         GC_m2s (type), GC_m2s (payload_type), payload_id,
+         GC_m2s (type), GC_m2s (payload_type),
+         ntohl (payload_id.pid),
          GCC_2s (c), c, GC_f2s (fwd), GCP_2s (peer), size);
 
     if (NULL == peer->connections)
@@ -1227,8 +1230,11 @@ GCP_send (struct CadetPeer *peer,
         {
             LOG (GNUNET_ERROR_TYPE_WARNING,
                  "DD %s (%s %u) on conn %s %s (random drop for testing)\n",
-                 GC_m2s (q->type), GC_m2s (q->payload_type),
-                 q->payload_id, GCC_2s (c), GC_f2s (q->c_fwd));
+                 GC_m2s (q->type),
+                 GC_m2s (q->payload_type),
+                 ntohl (q->payload_id.pid),
+                 GCC_2s (c),
+                 GC_f2s (q->c_fwd));
             q->drop_task = GNUNET_SCHEDULER_add_now (&drop_cb,
                                                      q);
             return q;
diff --git a/src/cadet/gnunet-service-cadet_peer.h b/src/cadet/gnunet-service-cadet_peer.h
index 37d735bf5..1e206e10f 100644
--- a/src/cadet/gnunet-service-cadet_peer.h
+++ b/src/cadet/gnunet-service-cadet_peer.h
@@ -69,8 +69,12 @@ struct CadetPeerQueue;
  */
 typedef void
 (*GCP_sent) (void *cls,
-             struct CadetConnection *c, int fwd, int sent,
-             uint16_t type, uint16_t payload_type, uint32_t pid,
+             struct CadetConnection *c,
+             int fwd,
+             int sent,
+             uint16_t type,
+             uint16_t payload_type,
+             struct CadetEncryptedMessageIdentifier pid,
              size_t size,
              struct GNUNET_TIME_Relative wait);
 
@@ -166,7 +170,7 @@ struct CadetPeerQueue *
 GCP_send (struct CadetPeer *peer,
           const struct GNUNET_MessageHeader *message,
           uint16_t payload_type,
-          uint32_t payload_id,
+          struct CadetEncryptedMessageIdentifier payload_id,
           struct CadetConnection *c,
           int fwd,
           GCP_sent cont,
diff --git a/src/cadet/gnunet-service-cadet_tunnel.c b/src/cadet/gnunet-service-cadet_tunnel.c
index df1cfa16e..5e0f5bf4f 100644
--- a/src/cadet/gnunet-service-cadet_tunnel.c
+++ b/src/cadet/gnunet-service-cadet_tunnel.c
@@ -1327,7 +1327,6 @@ send_prebuilt_message (const struct GNUNET_MessageHeader *message,
   size_t size = ntohs (message->size);
   char cbuf[sizeof (struct GNUNET_CADET_ConnectionEncryptedMessage) + size] GNUNET_ALIGN;
   size_t esize;
-  uint32_t mid;
   uint16_t type;
   int fwd;
 
@@ -1379,38 +1378,22 @@ send_prebuilt_message (const struct GNUNET_MessageHeader *message,
   }
   fwd = GCC_is_origin (c, GNUNET_YES);
   ax_msg->cid = *GCC_get_id (c);
-  ax_msg->pid = htonl (GCC_get_pid (c, fwd));
+  ax_msg->cemi = GCC_get_pid (c, fwd);
 
-  mid = 0;
-  type = ntohs (message->type);
-  switch (type)
-  {
-    case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_DATA:
-    case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_DATA_ACK:
-      if (GNUNET_MESSAGE_TYPE_CADET_CHANNEL_DATA == type)
-        mid = ntohl (((struct GNUNET_CADET_ChannelDataMessage *) message)->mid);
-      else
-        mid = ntohl (((struct GNUNET_CADET_ChannelDataAckMessage *) message)->mid);
-      /* Fall thru */
-    case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_KEEPALIVE:
-    case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_CREATE:
-    case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_DESTROY:
-    case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_CREATE_ACK:
-    case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_CREATE_NACK_DEPRECATED:
-      break;
-    default:
-      GNUNET_break (0);
-      LOG (GNUNET_ERROR_TYPE_ERROR, "type %s not valid\n", GC_m2s (type));
-  }
+  type = htons (message->type);
   LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "Sending message of type %s with PID %u and CID %s\n",
+       "Sending message of type %s with CEMI %u and CID %s\n",
        GC_m2s (type),
-       htonl (ax_msg->pid),
+       htonl (ax_msg->cemi.pid),
        GNUNET_sh2s (&ax_msg->cid.connection_of_tunnel));
 
   if (NULL == cont)
   {
-    (void) GCC_send_prebuilt_message (msg, type, mid, c, fwd,
+    (void) GCC_send_prebuilt_message (msg,
+                                      type,
+                                      ax_msg->cemi,
+                                      c,
+                                      fwd,
                                       force, NULL, NULL);
     return NULL;
   }
@@ -1425,7 +1408,12 @@ send_prebuilt_message (const struct GNUNET_MessageHeader *message,
   }
   tq->cont = cont;
   tq->cont_cls = cont_cls;
-  tq->cq = GCC_send_prebuilt_message (msg, type, mid, c, fwd, force,
+  tq->cq = GCC_send_prebuilt_message (msg,
+                                      type,
+                                      ax_msg->cemi,
+                                      c,
+                                      fwd,
+                                      force,
                                       &tun_message_sent, tq);
   GNUNET_assert (NULL != tq->cq);
 
@@ -3204,7 +3192,8 @@ GCT_has_queued_traffic (struct CadetTunnel *t)
  */
 struct CadetTunnelQueue *
 GCT_send_prebuilt_message (const struct GNUNET_MessageHeader *message,
-                           struct CadetTunnel *t, struct CadetConnection *c,
+                           struct CadetTunnel *t,
+                           struct CadetConnection *c,
                            int force, GCT_sent cont, void *cont_cls)
 {
   return send_prebuilt_message (message, t, c, force, cont, cont_cls, NULL);
@@ -3220,6 +3209,7 @@ GCT_send_prebuilt_message (const struct GNUNET_MessageHeader *message,
 void
 GCT_send_kx (struct CadetTunnel *t, int force_reply)
 {
+  static struct CadetEncryptedMessageIdentifier zero;
   struct CadetConnection *c;
   struct GNUNET_CADET_TunnelKeyExchangeMessage msg;
   enum GNUNET_CADET_KX_Flags flags;
@@ -3253,8 +3243,11 @@ GCT_send_kx (struct CadetTunnel *t, int force_reply)
   GNUNET_CRYPTO_ecdhe_key_get_public (t->ax->kx_0, &msg.ephemeral_key);
   GNUNET_CRYPTO_ecdhe_key_get_public (t->ax->DHRs, &msg.ratchet_key);
 
-  t->ephm_h = GCC_send_prebuilt_message (&msg.header, UINT16_MAX, 0,
-                                         c, GCC_is_origin (c, GNUNET_YES),
+  t->ephm_h = GCC_send_prebuilt_message (&msg.header,
+                                         UINT16_MAX,
+                                         zero,
+                                         c,
+                                         GCC_is_origin (c, GNUNET_YES),
                                          GNUNET_YES, &ephm_sent, t);
   if (CADET_TUNNEL_KEY_UNINITIALIZED == t->estate)
     GCT_change_estate (t, CADET_TUNNEL_KEY_SENT);