more work on channel/tunnel logic

10 files changed, 136 insertions, 142 deletions

diff --git a/src/cadet/cadet_protocol.h b/src/cadet/cadet_protocol.h
index cf32e0d6d..f85ef17ae 100644
--- a/src/cadet/cadet_protocol.h
+++ b/src/cadet/cadet_protocol.h
@@ -337,7 +337,7 @@ struct GNUNET_CADET_ConnectionEncryptedAckMessage
   /**
    * Maximum packet ID authorized.
    */
-  struct CadetEncryptedMessageIdentifier cemi;
+  struct CadetEncryptedMessageIdentifier cemi_max;
 
   /**
    * ID of the connection.
@@ -379,12 +379,13 @@ struct GNUNET_CADET_ChannelOpenMessage
 
 
 /**
- * Message to manage a Channel (ACK, NACK, Destroy).
+ * Message to manage a Channel (CHANNEL_CREATE_ACK, CHANNEL_DESTROY).
  */
 struct GNUNET_CADET_ChannelManageMessage
 {
   /**
-   * Type: #GNUNET_MESSAGE_TYPE_CADET_CHANNEL_{ACK|NACK|DESTROY}
+   * Type: #GNUNET_MESSAGE_TYPE_CADET_CHANNEL_CREATE_ACK or
+   * #GNUNET_MESSAGE_TYPE_CADET_CHANNEL_DESTROY
    */
   struct GNUNET_MessageHeader header;
 
diff --git a/src/cadet/gnunet-service-cadet-new_channel.c b/src/cadet/gnunet-service-cadet-new_channel.c
index 5acd098b6..70f16dbe6 100644
--- a/src/cadet/gnunet-service-cadet-new_channel.c
+++ b/src/cadet/gnunet-service-cadet-new_channel.c
@@ -18,7 +18,6 @@
      Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
      Boston, MA 02110-1301, USA.
 */
-
 /**
  * @file cadet/gnunet-service-cadet-new_channel.c
  * @brief logical links between CADET clients
@@ -26,10 +25,11 @@
  * @author Christian Grothoff
  *
  * TODO:
- * - estimate max bandwidth using bursts and use to optimize
- *   transmission rate(s)
+ * - estimate max bandwidth using bursts and use to for CONGESTION CONTROL!
+ * - check that '0xFFULL' really is sufficient for flow control!
+ * - what about the 'no buffer' option?
+ * - what about the 'out-of-order' option?
  */
-
 #include "platform.h"
 #include "gnunet_util_lib.h"
 #include "cadet.h"
@@ -259,7 +259,7 @@ struct CadetChannel
   /**
    * Number identifying this channel in its tunnel.
    */
-  struct GNUNET_CADET_ChannelTunnelNumber gid;
+  struct GNUNET_CADET_ChannelTunnelNumber chid;
 
   /**
    * Local tunnel number for local client owning the channel.
@@ -324,10 +324,10 @@ GCCH_2s (const struct CadetChannel *ch)
     return "(NULL Channel)";
   GNUNET_snprintf (buf,
                    sizeof (buf),
-                   "%s:%s gid:%X (%X)",
+                   "%s:%s chid:%X (%X)",
                    GCT_2s (ch->t),
                    GNUNET_h2s (&ch->port),
-                   ch->gid,
+                   ch->chid,
                    ntohl (ch->lid.channel_of_client));
   return buf;
 }
@@ -343,7 +343,7 @@ GCCH_2s (const struct CadetChannel *ch)
 struct GNUNET_CADET_ChannelTunnelNumber
 GCCH_get_id (const struct CadetChannel *ch)
 {
-  return ch->gid;
+  return ch->chid;
 }
 
 
@@ -391,7 +391,7 @@ channel_destroy (struct CadetChannel *ch)
   }
   GCT_remove_channel (ch->t,
                       ch,
-                      ch->gid);
+                      ch->chid);
   GNUNET_free (ch);
 }
 
@@ -447,7 +447,7 @@ send_create (void *cls)
   msgcc.header.type = htons (GNUNET_MESSAGE_TYPE_CADET_CHANNEL_OPEN);
   msgcc.opt = htonl (options);
   msgcc.port = ch->port;
-  msgcc.chid = ch->gid;
+  msgcc.chid = ch->chid;
   ch->state = CADET_CHANNEL_CREATE_SENT;
   ch->last_control_qe = GCT_send (ch->t,
                                   &msgcc.header,
@@ -483,8 +483,8 @@ GCCH_channel_local_new (struct CadetClient *owner,
   ch->port = *port;
   ch->t = GCP_get_tunnel (destination,
                           GNUNET_YES);
-  ch->gid = GCT_add_channel (ch->t,
-                             ch);
+  ch->chid = GCT_add_channel (ch->t,
+                              ch);
   ch->retry_time = CADET_INITIAL_RETRANSMIT_TIME;
   ch->nobuffer = (0 != (options & GNUNET_CADET_OPTION_NOBUFFER));
   ch->reliable = (0 != (options & GNUNET_CADET_OPTION_RELIABLE));
@@ -516,17 +516,17 @@ timeout_closed_cb (void *cls)
 
 
 /**
- * Create a new channel.
+ * Create a new channel based on a request coming in over the network.
  *
  * @param t tunnel to the remote peer
- * @param gid identifier of this channel in the tunnel
+ * @param chid identifier of this channel in the tunnel
  * @param port desired local port
  * @param options options for the channel
  * @return handle to the new channel
  */
 struct CadetChannel *
 GCCH_channel_incoming_new (struct CadetTunnel *t,
-                           struct GNUNET_CADET_ChannelTunnelNumber gid,
+                           struct GNUNET_CADET_ChannelTunnelNumber chid,
                            const struct GNUNET_HashCode *port,
                            uint32_t options)
 {
@@ -538,7 +538,7 @@ GCCH_channel_incoming_new (struct CadetTunnel *t,
                                     or adjust dynamically... */
   ch->port = *port;
   ch->t = t;
-  ch->gid = gid;
+  ch->chid = chid;
   ch->retry_time = CADET_INITIAL_RETRANSMIT_TIME;
   ch->nobuffer = (0 != (options & GNUNET_CADET_OPTION_NOBUFFER));
   ch->reliable = (0 != (options & GNUNET_CADET_OPTION_RELIABLE));
@@ -602,7 +602,7 @@ send_channel_ack (struct CadetChannel *ch)
 
   msg.header.type = htons (GNUNET_MESSAGE_TYPE_CADET_CHANNEL_APP_DATA_ACK);
   msg.header.size = htons (sizeof (msg));
-  msg.gid = ch->gid;
+  msg.gid = ch->chid;
   msg.mid.mid = htonl (ntohl (ch->mid_recv.mid) - 1);
   msg.futures = GNUNET_htonll (ch->mid_futures);
   if (NULL != ch->last_control_qe)
@@ -694,6 +694,8 @@ GCCH_channel_local_destroy (struct CadetChannel *ch)
     return;
   }
   /* Nothing left to do, just finish destruction */
+  GCT_send_channel_destroy (ch->t,
+                            ch->chid);
   channel_destroy (ch);
 }
 
@@ -721,6 +723,8 @@ GCCH_channel_incoming_destroy (struct CadetChannel *ch)
     return;
   }
   /* Nothing left to do, just finish destruction */
+  GCT_send_channel_destroy (ch->t,
+                            ch->chid);
   channel_destroy (ch);
 }
 
@@ -930,7 +934,7 @@ GCCH_handle_local_data (struct CadetChannel *ch,
   crm->data_message.header.type = htons (GNUNET_MESSAGE_TYPE_CADET_CHANNEL_APP_DATA);
   ch->mid_send.mid = htonl (ntohl (ch->mid_send.mid) + 1);
   crm->data_message.mid = ch->mid_send;
-  crm->data_message.gid = ch->gid;
+  crm->data_message.gid = ch->chid;
   GNUNET_memcpy (&crm[1],
                  message,
                  payload_size);
@@ -1001,6 +1005,8 @@ send_client_buffered_data (struct CadetChannel *ch)
     return;
   if (GNUNET_NO == ch->destroy)
     return;
+  GCT_send_channel_destroy (ch->t,
+                            ch->chid);
   channel_destroy (ch);
 }
 
@@ -1047,7 +1053,7 @@ GCCH_debug (struct CadetChannel *ch,
   LOG2 (level,
         "CHN Channel %s:%X (%p)\n",
         GCT_2s (ch->t),
-        ch->gid,
+        ch->chid,
         ch);
   if (NULL != ch->owner)
   {
diff --git a/src/cadet/gnunet-service-cadet-new_channel.h b/src/cadet/gnunet-service-cadet-new_channel.h
index 8caa254d1..0d56d8ae0 100644
--- a/src/cadet/gnunet-service-cadet-new_channel.h
+++ b/src/cadet/gnunet-service-cadet-new_channel.h
@@ -107,7 +107,6 @@ GCCH_bind (struct CadetChannel *ch,
            struct CadetClient *c);
 
 
-
 /**
  * Destroy locally created channel.  Called by the
  * local client, so no need to tell the client.
@@ -119,10 +118,10 @@ GCCH_channel_local_destroy (struct CadetChannel *ch);
 
 
 /**
- * Create a new channel.
+ * Create a new channel based on a request coming in over the network.
  *
  * @param t tunnel to the remote peer
- * @param gid identifier of this channel in the tunnel
+ * @param chid identifier of this channel in the tunnel
  * @param origin peer to who initiated the channel
  * @param port desired local port
  * @param options options for the channel
@@ -130,7 +129,7 @@ GCCH_channel_local_destroy (struct CadetChannel *ch);
  */
 struct CadetChannel *
 GCCH_channel_incoming_new (struct CadetTunnel *t,
-                           struct GNUNET_CADET_ChannelTunnelNumber gid,
+                           struct GNUNET_CADET_ChannelTunnelNumber chid,
                            const struct GNUNET_HashCode *port,
                            uint32_t options);
 
diff --git a/src/cadet/gnunet-service-cadet-new_connection.c b/src/cadet/gnunet-service-cadet-new_connection.c
index bf88d78e1..5eb6335a2 100644
--- a/src/cadet/gnunet-service-cadet-new_connection.c
+++ b/src/cadet/gnunet-service-cadet-new_connection.c
@@ -27,8 +27,8 @@
  * @author Christian Grothoff
  *
  * TODO:
- * - keepalive messages
- * - keep performance metrics (?)
+ * - Optimization: keepalive messages / timeout (timeout to be done @ peer level!)
+ * - Optimization: keep performance metrics (?)
  */
 #include "platform.h"
 #include "gnunet-service-cadet-new_channel.h"
diff --git a/src/cadet/gnunet-service-cadet-new_connection.h b/src/cadet/gnunet-service-cadet-new_connection.h
index 99426776d..31a2e80bb 100644
--- a/src/cadet/gnunet-service-cadet-new_connection.h
+++ b/src/cadet/gnunet-service-cadet-new_connection.h
@@ -122,6 +122,17 @@ GCC_handle_connection_ack (struct CadetConnection *cc);
 
 
 /**
+ * We got a #GNUNET_MESSAGE_TYPE_CADET_CONNECTION_CREATE for a
+ * connection that we already have.  Either our ACK got lost
+ * or something is fishy.  Consider retransmitting the ACK.
+ *
+ * @param cc connection that got the duplicate CREATE
+ */
+void
+GCC_handle_duplicate_create (struct CadetConnection *cc);
+
+
+/**
  * Handle KX message.
  *
  * @param cc connection that received encrypted message
diff --git a/src/cadet/gnunet-service-cadet-new_core.c b/src/cadet/gnunet-service-cadet-new_core.c
index 9ce4418de..a5d114b34 100644
--- a/src/cadet/gnunet-service-cadet-new_core.c
+++ b/src/cadet/gnunet-service-cadet-new_core.c
@@ -27,10 +27,7 @@
  * All functions in this file should use the prefix GCO (Gnunet Cadet cOre (bottom))
  *
  * TODO:
- * - pass encrypted ACK to connection (!)
- * - given BROKEN messages, destroy paths (?)
- * -
- * - handle POLL (if needed)
+ * - Optimization: given BROKEN messages, destroy paths (?)
  */
 #include "platform.h"
 #include "gnunet-service-cadet-new_core.h"
@@ -422,8 +419,7 @@ handle_connection_create (void *cls,
                                              &msg->cid.connection_of_tunnel);
     if (NULL != cc)
     {
-      /* Duplicate CREATE, likely our ACK got lost, retransmit the ACK! */
-      GNUNET_break (0); // FIXME: not implemented!
+      GCC_handle_duplicate_create (cc);
       return;
     }
 
@@ -604,68 +600,6 @@ handle_connection_destroy (void *cls,
 
 
 /**
- * Handle for #GNUNET_MESSAGE_TYPE_CADET_TUNNEL_HOP_BY_HOP_ENCRYPTED_ACK.
- *
- * @param cls Closure (CadetPeer for neighbor that sent the message).
- * @param msg Message itself.
- */
-static void
-handle_hop_by_hop_encrypted_ack (void *cls,
-                                 const struct GNUNET_CADET_ConnectionEncryptedAckMessage *msg)
-{
-  struct CadetPeer *peer = cls;
-  struct CadetConnection *cc;
-
-  /* First, check if message belongs to a connection that ends here. */
-  cc = GNUNET_CONTAINER_multishortmap_get (connections,
-                                           &msg->cid.connection_of_tunnel);
-  if (NULL != cc)
-  {
-    /* verify message came from the right direction */
-    struct CadetPeerPath *path = GCC_get_path (cc);
-
-    if (peer !=
-        GCPP_get_peer_at_offset (path,
-                                 0))
-    {
-      /* received message from unexpected direction, ignore! */
-      GNUNET_break_op (0);
-      return;
-    }
-#if FIXME
-    GCC_handle_ack (peer,
-                    msg);
-#endif
-    return;
-  }
-
-  /* We're just an intermediary peer, route the message along its path */
-  route_message (peer,
-                 &msg->cid,
-                 &msg->header);
-}
-
-
-/**
- * Handle for #GNUNET_MESSAGE_TYPE_CADET_TUNNEL_ENCRYPTED_POLL
- *
- * @param cls Closure (CadetPeer for neighbor that sent the message).
- * @param msg Message itself.
- */
-static void
-handle_poll (void *cls,
-             const struct GNUNET_CADET_ConnectionHopByHopPollMessage *msg)
-{
-  struct CadetPeer *peer = cls;
-
-#if FIXME
-  GCC_handle_poll (peer,
-                   msg);
-#endif
-}
-
-
-/**
  * Handle for #GNUNET_MESSAGE_TYPE_CADET_TUNNEL_KX
  *
  * @param cls Closure (CadetPeer for neighbor that sent the message).
@@ -755,7 +689,6 @@ handle_tunnel_encrypted (void *cls,
                           msg);
     return;
   }
-
   /* We're just an intermediary peer, route the message along its path */
   route_message (peer,
                  &msg->cid,
@@ -855,14 +788,6 @@ GCO_init (const struct GNUNET_CONFIGURATION_Handle *c)
                              GNUNET_MESSAGE_TYPE_CADET_CONNECTION_DESTROY,
                              struct GNUNET_CADET_ConnectionDestroyMessage,
                              NULL),
-    GNUNET_MQ_hd_fixed_size (hop_by_hop_encrypted_ack,
-                             GNUNET_MESSAGE_TYPE_CADET_CONNECTION_HOP_BY_HOP_ENCRYPTED_ACK,
-                             struct GNUNET_CADET_ConnectionEncryptedAckMessage,
-                             NULL),
-    GNUNET_MQ_hd_fixed_size (poll,
-                             GNUNET_MESSAGE_TYPE_CADET_TUNNEL_ENCRYPTED_POLL,
-                             struct GNUNET_CADET_ConnectionHopByHopPollMessage,
-                             NULL),
     GNUNET_MQ_hd_fixed_size (tunnel_kx,
                              GNUNET_MESSAGE_TYPE_CADET_TUNNEL_KX,
                              struct GNUNET_CADET_TunnelKeyExchangeMessage,
diff --git a/src/cadet/gnunet-service-cadet-new_tunnels.c b/src/cadet/gnunet-service-cadet-new_tunnels.c
index 23b270b82..6873fb396 100644
--- a/src/cadet/gnunet-service-cadet-new_tunnels.c
+++ b/src/cadet/gnunet-service-cadet-new_tunnels.c
@@ -1,4 +1,3 @@
-
 /*
      This file is part of GNUnet.
      Copyright (C) 2013, 2017 GNUnet e.V.
@@ -18,7 +17,6 @@
      Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
      Boston, MA 02110-1301, USA.
 */
-
 /**
  * @file cadet/gnunet-service-cadet-new_tunnels.c
  * @brief Information we track per tunnel.
@@ -26,12 +24,12 @@
  * @author Christian Grothoff
  *
  * FIXME:
+ * - clean up KX logic!
+ * - implement sending and receiving KX messages
+ * - implement processing of incoming decrypted plaintext messages
  * - when managing connections, distinguish those that
  *   have (recently) had traffic from those that were
  *   never ready (or not recently)
- * - implement sending and receiving KX messages
- * - implement processing of incoming decrypted plaintext messages
- * - clean up KX logic!
  */
 #include "platform.h"
 #include "gnunet_util_lib.h"
@@ -1306,32 +1304,52 @@ GCT_handle_kx (struct CadetTConnection *ct,
 
 
 /**
- * Add a channel to a tunnel.
+ * Compute the next free channel tunnel number for this tunnel.
  *
- * @param t Tunnel.
- * @param ch Channel
- * @return unique number identifying @a ch within @a t
+ * @param t the tunnel
+ * @return unused number that can uniquely identify a channel in the tunnel
  */
-struct GNUNET_CADET_ChannelTunnelNumber
-GCT_add_channel (struct CadetTunnel *t,
-                 struct CadetChannel *ch)
+static struct GNUNET_CADET_ChannelTunnelNumber
+get_next_free_chid (struct CadetTunnel *t)
 {
   struct GNUNET_CADET_ChannelTunnelNumber ret;
   uint32_t chid;
 
+  /* FIXME: this logic does NOT prevent both ends of the
+     channel from picking the same CHID!
+     Need to reserve one bit of the CHID for the
+     direction, i.e. which side established the connection! */
   chid = ntohl (t->next_chid.cn);
   while (NULL !=
          GNUNET_CONTAINER_multihashmap32_get (t->channels,
                                               chid))
     chid++;
+  t->next_chid.cn = htonl (chid + 1);
+  ret.cn = ntohl (chid);
+  return ret;
+}
+
+
+/**
+ * Add a channel to a tunnel.
+ *
+ * @param t Tunnel.
+ * @param ch Channel
+ * @return unique number identifying @a ch within @a t
+ */
+struct GNUNET_CADET_ChannelTunnelNumber
+GCT_add_channel (struct CadetTunnel *t,
+                 struct CadetChannel *ch)
+{
+  struct GNUNET_CADET_ChannelTunnelNumber chid;
+
+  chid = get_next_free_chid (t);
   GNUNET_assert (GNUNET_YES ==
                  GNUNET_CONTAINER_multihashmap32_put (t->channels,
-                                                      chid,
+                                                      ntohl (chid.cn),
                                                       ch,
                                                       GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
-  t->next_chid.cn = htonl (chid + 1);
-  ret.cn = htonl (chid);
-  return ret;
+  return chid;
 }
 
 
@@ -1638,7 +1656,8 @@ handle_plaintext_data_ack (void *cls,
 
 
 /**
- *
+ * We have received a request to open a channel to a port from
+ * another peer.  Creates the incoming channel.
  *
  * @param cls the `struct CadetTunnel` for which we decrypted the message
  * @param cc the message we received on the tunnel
@@ -1648,27 +1667,40 @@ handle_plaintext_channel_create (void *cls,
                                  const struct GNUNET_CADET_ChannelOpenMessage *cc)
 {
   struct CadetTunnel *t = cls;
-  GNUNET_break (0); // FIXME!
+  struct CadetChannel *ch;
+  struct GNUNET_CADET_ChannelTunnelNumber chid;
+
+  chid = get_next_free_chid (t);
+  ch = GCCH_channel_incoming_new (t,
+                                  chid,
+                                  &cc->port,
+                                  ntohl (cc->opt));
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CONTAINER_multihashmap32_put (t->channels,
+                                                      ntohl (chid.cn),
+                                                      ch,
+                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
 }
 
 
 /**
+ * Send a DESTROY message via the tunnel.
  *
- *
- * @param cls the `struct CadetTunnel` for which we decrypted the message
- * @param cm the message we received on the tunnel
+ * @param t the tunnel to transmit over
+ * @param chid ID of the channel to destroy
  */
-static void
-handle_plaintext_channel_nack (void *cls,
-                               const struct GNUNET_CADET_ChannelManageMessage *cm)
+void
+GCT_send_channel_destroy (struct CadetTunnel *t,
+                          struct GNUNET_CADET_ChannelTunnelNumber chid)
 {
-  struct CadetTunnel *t = cls;
   GNUNET_break (0); // FIXME!
 }
 
 
 /**
- *
+ * We have received confirmation from the target peer that the
+ * given channel could be established (the port is open).
+ * Tell the client.
  *
  * @param cls the `struct CadetTunnel` for which we decrypted the message
  * @param cm the message we received on the tunnel
@@ -1678,6 +1710,18 @@ handle_plaintext_channel_ack (void *cls,
                               const struct GNUNET_CADET_ChannelManageMessage *cm)
 {
   struct CadetTunnel *t = cls;
+  struct CadetChannel *ch;
+
+  ch = lookup_channel (t,
+                       cm->chid);
+  if (NULL == ch)
+  {
+    /* We don't know about such a channel, might have been destroyed on our
+       end in the meantime, or never existed. Send back a DESTROY. */
+    GCT_send_channel_destroy (t,
+                              cm->chid);
+    return;
+  }
   GNUNET_break (0); // FIXME!
 }
 
@@ -1763,10 +1807,6 @@ GCT_create_tunnel (struct CadetPeer *destination)
                              GNUNET_MESSAGE_TYPE_CADET_CHANNEL_OPEN,
                              struct GNUNET_CADET_ChannelOpenMessage,
                              NULL),
-    GNUNET_MQ_hd_fixed_size (plaintext_channel_nack,
-                             GNUNET_MESSAGE_TYPE_CADET_CHANNEL_OPEN_NACK_DEPRECATED,
-                             struct GNUNET_CADET_ChannelManageMessage,
-                             NULL),
     GNUNET_MQ_hd_fixed_size (plaintext_channel_ack,
                              GNUNET_MESSAGE_TYPE_CADET_CHANNEL_OPEN_ACK,
                              struct GNUNET_CADET_ChannelManageMessage,
diff --git a/src/cadet/gnunet-service-cadet-new_tunnels.h b/src/cadet/gnunet-service-cadet-new_tunnels.h
index 82e4b0da6..cd96a50bc 100644
--- a/src/cadet/gnunet-service-cadet-new_tunnels.h
+++ b/src/cadet/gnunet-service-cadet-new_tunnels.h
@@ -202,6 +202,17 @@ GCT_remove_channel (struct CadetTunnel *t,
 
 
 /**
+ * Send a DESTROY message via the tunnel.
+ *
+ * @param t the tunnel to transmit over
+ * @param chid ID of the channel to destroy
+ */
+void
+GCT_send_channel_destroy (struct CadetTunnel *t,
+                          struct GNUNET_CADET_ChannelTunnelNumber chid);
+
+
+/**
  * Sends an already built message on a tunnel, encrypting it and
  * choosing the best connection if not provided.
  *
diff --git a/src/cadet/gnunet-service-cadet_connection.c b/src/cadet/gnunet-service-cadet_connection.c
index 931b32b95..c4802abde 100644
--- a/src/cadet/gnunet-service-cadet_connection.c
+++ b/src/cadet/gnunet-service-cadet_connection.c
@@ -617,7 +617,7 @@ send_ack (struct CadetConnection *c,
   /* Build ACK message and send on conn */
   msg.header.size = htons (sizeof (msg));
   msg.header.type = htons (GNUNET_MESSAGE_TYPE_CADET_CONNECTION_HOP_BY_HOP_ENCRYPTED_ACK);
-  msg.cemi = ack_cemi;
+  msg.cemi_max = ack_cemi;
   msg.cid = c->id;
 
   prev_fc->ack_msg = GCC_send_prebuilt_message (&msg.header,
@@ -2373,7 +2373,7 @@ GCC_handle_ack (struct CadetPeer *peer,
     return;
   }
 
-  ack = msg->cemi;
+  ack = msg->cemi_max;
   LOG (GNUNET_ERROR_TYPE_DEBUG, " %s ACK %u (was %u)\n",
        GC_f2s (fwd),
        ntohl (ack.pid),
diff --git a/src/cadet/gnunet-service-cadet_tunnel.c b/src/cadet/gnunet-service-cadet_tunnel.c
index 65775ce66..31c9b9e1c 100644
--- a/src/cadet/gnunet-service-cadet_tunnel.c
+++ b/src/cadet/gnunet-service-cadet_tunnel.c
@@ -1,6 +1,6 @@
 /*
      This file is part of GNUnet.
-     Copyright (C) 2013 GNUnet e.V.
+     Copyright (C) 2013, 2017 GNUnet e.V.
 
      GNUnet is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published
@@ -17,16 +17,17 @@
      Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
      Boston, MA 02110-1301, USA.
 */
-
+/**
+ * @file cadet/gnunet-service-cadet_tunnel.c
+ * @brief logical links between CADET clients
+ * @author Bartlomiej Polot
+ */
 #include "platform.h"
 #include "gnunet_util_lib.h"
-
 #include "gnunet_signatures.h"
 #include "gnunet_statistics_service.h"
-
 #include "cadet_protocol.h"
 #include "cadet_path.h"
-
 #include "gnunet-service-cadet_tunnel.h"
 #include "gnunet-service-cadet_connection.h"
 #include "gnunet-service-cadet_channel.h"