3.1.5.1.6 STATE_CANCEL

 If (UploadSuspended is TRUE)
    Set State to SUSPEND
    Return from this state.
  
 Send CANCEL-SESSION message to the server.
  
 If (error encountered in send)
    Set State to ERROR
    Return from this state.
  
 Receive Ack for CANCEL-SESSION response from the server.
  
 If (error encountered while receiving or reading the response info)
    Set state to ERROR
    Return from this state.