+/** Add a new attribute-value pair to \a pkt. */
+int rs_packet_add_avp(struct rs_packet *pkt,
+ unsigned int attr, unsigned int vendor,
+ const void *data, size_t data_len);
+
+/** Append a new attribute to packet \a pkt. Note that this function
+ encodes the attribute and therefore might require the secret
+ shared with the thought recipient to be set in pkt->rpkt. Note
+ also that this function marks \a pkt as already encoded and can
+ not be used on packets with non-encoded value-pairs already
+ added. */