Default Networked Device

ladyDia

Nov 14th, 2024 (edited)

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--Variables
local networkDeviceSide = "left" --Change this to where network device is
deviceType = "default"
ipAddress = {-1,-1,-1} --We aren't working with subnets yet
routerID = -1 --The computer ID of the router, allowing for responses to be returned
message = {}
packet = {}
localFunctions = {}
--[[
All data packets have a set structure made of four sections
First Section - IP Address of target system
Second Section - IP Address of sending system
Third Section - Type of packet being sent (what protocol does packet follow)
Fourth Section - The main data the packet is transporting
For testing, the IP address will be the same as the device ID.
In the future this will be changed to allow for proper routing and
security measures.
The protocol the packet follows is a string in all caps
(CDP,ERP,DRP,UPP,etc) to allow for universal understanding (and style)
An IP address of 0 for the target system means that the packet is for
the router to work with. Trying to assign a different device this IP will fail
as the router will intercept all packets with that IP.
--]]
local function sendPacket (
targetIP, --Array
protocol, --String
data --Any
)
--[[
This function sends a packet to an IP address in the network.
Each packet needs to follow the rules of packet construction.
If the target IP is 0 then the packet will be sent to the default router.
If the sending IP is -1 then that means the IP hasn't been set yet
and will need to be to recieve packets from devices other than the router.
--]]
--Checking if there is a default router to send packet to, otherwise skip all code
if routerID == -1 then
print("Default router not set")
goto skip
end
--Checking if packet components have the right data types, otherwise skip all code
if not (type(targetIP) == "table") or not (type(protocol) == "string") then
print("Improperly formatted packet")
goto skip
end
--Packet construction
local packet = {
targetIP,
ipAddress,
protocol,
data
}
--Sending packet
print(targetIP[1].."."..targetIP[2].."."..targetIP[3].. " " .. ipAddress[1].."."..ipAddress[2].."."..ipAddress[3] .. " " .. protocol .. " " .. data)
rednet.send(routerID,packet)
::skip::
end
local function responseRDP ()
--[[
Router Discovery Protocol
Used by a router to discover other routers and build up a internetwork routing table.
After recieving a routing table, start adding it to router routing table
Routing table info:
1 - IP of router
2 - ID of next hop
3 - IP of next hop? (for future tracert)
4 - Number of hops to IP (To find shortest route)
Routers will not have themselves on their own routing tables
--]]
end
local function responseCDP ()
--[[
Computer Discovery Protocol
Used by a router to discover devices on the network then assign them IP addresses
and set itself as the device's default router. Devices already with an IP and
default router do not respond to CDP packets to avoid confusion on the side of
the router.
--]]
--If the device already has an IP and assigned Router then skip all code
if not (ipAddress == {-1,-1,-1}) and not (routerID == -1) then goto skip end
--Sets the device's default router to the device ID that sent the packet
routerID = message[1]
--Send CDP packet to router (IP 0) with the ID of the device
sendPacket({0,0,0},"CDP",os.getComputerID())
--An IP packet should be sent in the near future to this device to assign IP
::skip::
end
local function responseERP ()
--[[
Echo Request Protocol is used to see if an IP address is responding.
Sending an ERP packet will cause the device to send a return packet back to the
source device.
--]]
if packet[4] == "Ping" then
sendPacket(packet[2],"ERP","pong")
end
end
local function responseDRP ()
--Device Request Protocol
end
local function responseUPP ()
--Unknown Packet Protocol
end
local function responseIP ()
--[[
Internet Protocol
Used by router to give a device an IP address. Will only be accepted if the
router is the default router the device knows. If the default router is
unassigned then the IP packet is dropped. The data on the packet should
be a number.
--]]
--Checking if routerID is assigned
print(routerID)
if routerID == -1 then goto skip end
--Checking if routerID is the same as the message sender
if not (routerID == message[1]) then goto skip end
--Setting the IP of the device to the one sent by the router
ipAddress = packet[4]
--Sending IP packet with the device type to the router
sendPacket({0,0,0},"IP",deviceType)
::skip::
end
local function responseDP ()
--Data Packet
end
local function responseAP ()
--Acknowledgement Packet
end
function mainLoop ()
--This function runs continuously and allows the device to respond to requests and packets
while true do
print("Ready to recieve message")
--Wait until rednet message recieved
message = {rednet.receive()}
--Pulling out the packet inside of the message
packet = (message[2])
--Checking if packet is properly formatted, if it is not then drop packet and continue loop
if #packet < 4 then goto continue end
if packet[3] == "RDP" then goto continue end
if not (packet[3] == "CDP") then
print("Packet Type: " .. packet[3])
end
if localFunctions["response"..packet[3]] then
--If protocol exists
if not (packet[3] == "CDP") then
print("Running response "..packet[3])
end
localFunctions["response"..packet[3]]()
--table.insert(dataQueue,packet)
else
--Send UPP packet to source device if protocol is unknown
print("Unknown")
sendPacket(packet[1],"UPP","Unknown Packet Type: "..packet[3])
end
--]]
::continue::
--End of cycle upkeep
--Resetting last received message and packet back to their default states
message = {}
packet = {}
end
end
--Finding all of the local functions and storing them
index = 1
while true do
key, data = debug.getlocal(1,index)
if not key then break end
--print(key)
if type(data) == "function" then
if debug.getinfo(data, "S").what == "Lua" then
localFunctions[key] = data
end
end
index = index + 1
end
--Turning on the network capabilities of the device
peripheralNames = peripheral.getNames()
for i = 1, #peripheralNames, 1 do
if peripheral.hasType(peripheralNames[i],"modem") then
rednet.open(peripheralNames[i])
end
end
--Calling the mainLoop to start program
print("Starting mainLoop")
mainLoop()

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