Radio Modem and Wi-Fi Router

A Radio Modem (packet radio, 1971) lets a computer send net messages through the air to the computers around it. A Wi-Fi Router (1999) reaches twice as far, and all the routers that share a network name, an SSID, form one backbone across the world, like the Internet: a message that reaches one router comes out of all the others. As a peripheral, the radio tells its range, and the router lets a program read and set its SSID.

local router = peripheral.find("wifi_router")
router.set_ssid("brassworks")
print(router.range() .. " blocks")

#Setting up

Which computers. Wireless needs a Personal Computer, a Microcontroller or a Modern Computer. Older computers can still wrap a radio and call these methods, but net sends nothing through it.

Placing it. Put the radio against any face of the computer, or anywhere on the Data Cable network of the computer: one radio on the roof serves every computer of the building. A computer with several radios uses them all.

How far. Two radios hear each other when they are closer than the shorter of their two ranges:

A modem and a router talk up to 128 blocks, two routers up to 256. The server can scale every range (wirelessRangeMultiplier in computingages-server.toml, from 0.1 to 16). On a Create Aeronautics vehicle, distances use the real position of the vehicle.

The backbone. Routers that share an SSID are all linked, wherever they are in the same dimension. A computer is on that backbone when one of its own routers has the SSID, or when any of its radios, even a plain modem, is in range of a router of it. It then reaches every computer near any other router of the same SSID. A relay router must be attached to a computer that has wireless and sits in a loaded chunk (the computer does not need to run a program): a router standing alone in a field relays nothing. A router with no SSID is simply a radio with a longer range.

Messages that went through a router arrive with via set to "wifi", the others with "radio" (or "cable"). net.networks lists the backbones a computer can use. The whole story is in Networks.

#Range

local radio = peripheral.wrap("top")
print(radio.range(), "blocks")

#Network name

local radio = peripheral.wrap("top")
local ssid = radio.get_ssid()
if ssid == nil then
  print("a radio modem")
elseif ssid == "" then
  print("a router without a network name")
else
  print("a router of " .. ssid)
end

local router = peripheral.find("wifi_router")
router.set_ssid("brassworks")

#Examples

#A router that names itself

A startup file for each computer that carries a router: it sets the SSID once, and checks that it worked. Copy it to the base, the mine and the airship dock, and the three become one network.

local NETWORK = "brassworks"
local router = peripheral.find("wifi_router")
if router == nil then
  error("no Wi-Fi Router on this computer")
end
if router.get_ssid() ~= NETWORK then
  router.set_ssid(NETWORK)
  print("router joined " .. NETWORK)
end

#Every radio of a computer

Lists the radios a computer can use, against it or on its cable, with their range and their network name:

for _, name in ipairs(peripheral.list()) do
  local kind = peripheral.type(name)
  if kind == "radio_modem" or kind == "wifi_router" then
    local radio = peripheral.wrap(name)
    local ssid = radio.get_ssid()
    if ssid == nil then
      ssid = "-"
    elseif ssid == "" then
      ssid = "(no name)"
    end
    print(name .. "  " .. radio.range() .. " blocks  " .. ssid)
  end
end

On a computer with a router on top and a modem on the roof, it prints something like:

top  256 blocks  brassworks
radio_modem@14,80,-3  128 blocks  -