+/**
+ * A CREATE_ACK was received for this connection, process it.
+ *
+ * @param cc the connection that got the ACK.
+ */
+void
+GCC_handle_connection_create_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
+ * @param msg the key exchange message
+ */
+void
+GCC_handle_kx (struct CadetConnection *cc,
+ const struct GNUNET_CADET_TunnelKeyExchangeMessage *msg);
+
+
+/**
+ * Handle KX_AUTH message.
+ *
+ * @param cc connection that received encrypted message
+ * @param msg the key exchange message
+ */
+void
+GCC_handle_kx_auth (struct CadetConnection *cc,
+ const struct GNUNET_CADET_TunnelKeyExchangeAuthMessage *msg);
+
+
+/**
+ * Performance metrics for a connection.
+ */
+struct CadetConnectionMetrics
+{
+
+ /**
+ * Our current best estimate of the latency, based on a weighted
+ * average of at least @a latency_datapoints values.
+ */
+ struct GNUNET_TIME_Relative aged_latency;
+
+ /**
+ * When was this connection first established? (by us sending or
+ * receiving the CREATE_ACK for the first time)
+ */
+ struct GNUNET_TIME_Absolute age;
+
+ /**
+ * When was this connection last used? (by us sending or
+ * receiving a PAYLOAD message on it)
+ */
+ struct GNUNET_TIME_Absolute last_use;
+
+ /**
+ * How many packets that ought to generate an ACK did we send via
+ * this connection?
+ */
+ unsigned long long num_acked_transmissions;
+
+ /**
+ * Number of packets that were sent via this connection did actually
+ * receive an ACK? (Note: ACKs may be transmitted and lost via
+ * other connections, so this value should only be interpreted
+ * relative to @e num_acked_transmissions and in relation to other
+ * connections.)
+ */
+ unsigned long long num_successes;
+
+};
+
+
+/**
+ * Obtain performance @a metrics from @a cc.
+ *
+ * @param cc connection to query
+ * @return the metrics
+ */
+const struct CadetConnectionMetrics *
+GCC_get_metrics (struct CadetConnection *cc);
+
+
+/**
+ * Handle encrypted message.
+ *
+ * @param cc connection that received encrypted message
+ * @param msg the encrypted message to decrypt
+ */
+void
+GCC_handle_encrypted (struct CadetConnection *cc,
+ const struct GNUNET_CADET_TunnelEncryptedMessage *msg);
+
+
+/**
+ * We sent a message for which we expect to receive an ACK via
+ * the connection identified by @a cti.
+ *
+ * @param cid connection identifier where we expect an ACK
+ */
+void
+GCC_ack_expected (const struct GNUNET_CADET_ConnectionTunnelIdentifier *cid);
+
+
+/**
+ * We observed an ACK for a message that was originally sent via
+ * the connection identified by @a cti.
+ *
+ * @param cid connection identifier where we got an ACK for a message
+ * that was originally sent via this connection (the ACK
+ * may have gotten back to us via a different connection).
+ */
+void
+GCC_ack_observed (const struct GNUNET_CADET_ConnectionTunnelIdentifier *cid);
+
+
+/**
+ * We observed some the given @a latency on the connection
+ * identified by @a cti. (The same connection was taken
+ * in both directions.)
+ *
+ * @param cti connection identifier where we measured latency
+ * @param latency the observed latency
+ */
+void
+GCC_latency_observed (const struct GNUNET_CADET_ConnectionTunnelIdentifier *cti,
+ struct GNUNET_TIME_Relative latency);
+
+