This family of probe points is used to probe UDP layer activities. It contains the following probe points:
Fires whenever sending a udp message
Arguments:
sock
  network socket
size
  number of bytes to send
Fires whenever sending message is done
Arguments:
size
  number of bytes sent
Fires whenever a message is received
Arguments:
sock
  network socket
size
  number of bytes to be received
Fires whenever message receiving is done
Arguments:
size
  number of bytes received
Fires whenever udp is disconnected
Arguments:
sock
  network socket
flags
  flags (e.g. FIN, etc)
Fires when returning from udp.disconnect
Arguments:
ret
  error code (0: no error)