# Networking

This unit serves as an overarching importer of everything you need to do
networking in Dusk, that is:

* [com/link]
* [com/ip4]
* [com/arp]
* [com/udp]
* [com/tcp]

Then, it implements "incoming" as described in [com/link] associating every
known Frame Type to a handler.

Theoretically, this code should live in [com/link], but because of mutual
dependencies, there needs to be one big unit tying all the knots on top. This is
the one.

## The Active Links list

Links can be polled individually with "incoming", but this unit also maintains
a list of links to be polled, which is called the "Active Links" list. The
"activeincoming" word goes through this list and polls all active links one
after the other.

## Example usage

needs drv/nic/mynic com/net lib/coop
mynic$
mynic makeactive
net$

This setup above initializes a NIC, activates it and then registers
"activeincoming" as a [lib/coop] event generator. This means incoming packets
that Dusk support will be "fanned out" to applications that listen to those
events.

## API

### Values

activelink   Pointer to the last Link to be activated

### Words

incoming ( link -- )
  Check for incoming frames and redirect them to their appropriate handler in
  [com/ip4], [com/arp], etc..

  A mechanism using a Link is expected to regularly call this for each active
  link.

makeactive ( link -- )
  Add link to the active link list.

makeinactive ( link -- )
  Remove link from the active link list.

activeincoming ( -- )
  Goes through all active links and call "incoming" on them.

net$ ( -- )
  Registers "activeincoming" as a [lib/coop] event generator. Also, install
  TCPWork as a background application, which runs "tcpwork" on idling.

.dgram+ ( -- )
  Call .dgram from com/ip4, and depending of the Protocol field of the datagram,
  call a sub-printer such as .udp [com/udp] or .tcp [com/tcp] etc..

.frame ( -- )
  Print active frame depending on "frametype". For example, if type is FTIP4,
  call ".dgram+", if it's FTARP, call ".arp" etc..

.nextf ( -- )
  Call "nextf" [com/link] and then .frame if there is a next frame.