csp_send()
----------
called by: user
uses conn, uses RDP
copies flags from conn to PACKET
csp_sendto()
------------
called by: user
copies flags from user to packet
copies id to packet
csp_send_direct()
-----------------
called by: send, sendto, router, rdp
perfoms outgoing routing, selects interface
csp_send_direct_iface()
-----------------------
called by: csp_send_direct, bridge
calls output hook
copies id to packet <- This is duplicate of csp_sendto()
calls promisc
applies: crc, hmac
calls nexthop