DNS Server

-- DNS Server Software - Version 1.0.0                      --
-- Part of Interweb; Created for ComputerCraft              --
-- Written by Amarite1                                      --
-- http://t3kbau5.tk/                                       --
-- Liscense: http://creativecommons.org/licenses/by-sa/3.0/ --
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rednet.open('back') --change this to whatever side the internet cable/wireless modem is on. Copy/paste as many times as you need. Valid sides: back, front, top, bottom, left, right


--previously in the api
function resolve(domain)
    returnString = "ERROR"
    if fs.exists("records/" .. domain) then
        print("Domain exists")
        dnsRecord = fs.open("records/" .. domain, "r")
        recordType = dnsRecord.readLine()
        pointsTo = dnsRecord.readLine()
        if recordType == "A" then
            print(domain .. " has an A record!")
        elseif recordType == "C" then
            print("CNAME POINTS TO:" .. pointsTo)
            cnameRecord = fs.open("records/" .. pointsTo, "r")
            cnameType = cnameRecord.readLine()
            pointsTo = cnameRecord.readLine()
            cnameRecord.close()
        end
        dnsRecord.close()
        print(pointsTo)
        returnString = pointsTo
    else
        returnString = "Domain not registered"
    end
    print("Return String: " .. returnString)
    return returnString
end

function registerDomain(domain, recordType, pointsTo, password)
    if fs.exists("records/" .. domain) then
        return "Domain already registered"
    else
        if recordType ~= nil and pointsTo ~= nil then
            newRecord = fs.open("records/" .. domain, "w")
            newRecord.writeLine(recordType)
            newRecord.writeLine(pointsTo)
            newRecord.close()
            recordAdmin = fs.open("admin/" .. domain, "w")
            recordAdmin.writeLine(password)
            recordAdmin.close()
            return "Domain " .. domain .. " now has a/an " .. recordType .. " pointing to " .. pointsTo
        else
            return "Insufficient data provided"
        end
    end
end

--new functions, not in api
function modifyDomain(domain, password, recordType, pointsTo)
    if fs.exists("records/" .. domain) then
        recordAdmin = fs.open("admin/" .. domain, "r")
        if recordAdmin.readLine() == password then
            recordAdmin.close()
            record = fs.open("records/" .. domain, "w")
            record.writeLine(recordType)
            record.writeLine(pointsTo)
            record.close()
            return "Modified"
        else
            return "Incorrect password"
        end
    else
        return "Domain does not exist"
    end
end

function deleteDomain(domain, password)
    if fs.exists("records/" .. domain) then
        recordAdmin = fs.open("admin/" .. domain, "r")
        if recordAdmin.readLine() == password then
            recordAdmin.close()
            sleep(0.1)
            print(fs.isReadOnly("records/" .. domain))
            fs.delete("records/" .. domain)
            fs.delete("admin/" .. domain)
            return "Deleted"
        else
            return "Incorrect password"
        end
    else
        return "Domain does not exist"
    end
end
--split string function
function split(str, pat)
   local t = {}
   local fpat = "(.-)" .. pat
   local last_end = 1
   local s, e, cap = str:find(fpat, 1)
   while s do
          if s ~= 1 or cap ~= "" then
  table.insert(t,cap)
          end
          last_end = e+1
          s, e, cap = str:find(fpat, last_end)
   end
   if last_end <= #str then
          cap = str:sub(last_end)
          table.insert(t, cap)
   end
   return t
end
while true do
    sender, request, distance = rednet.receive(10)
    if request ~= nil then
        print(request)
        packetArray = {}
        packetArray = split(request, "<#>")
    end
    if request ~= nil and packetArray[1] == tostring(os.getComputerID()) then
        print("Message received")
        requestArray = split(packetArray[2], "+")
        print("Array created: " .. requestArray[1] .. " " .. requestArray[2])
        if requestArray[1] == "resolve" then
            print("Resolve " .. requestArray[2])
            resolveResult = resolve(requestArray[2])
            print("Resolve Result: " .. resolveResult)
            --rednet.send(sender, sender .. "<#>" .. resolveResult)
            sleep(0.1)
            rednet.send(sender, sender .. "<#>" .. resolveResult)
        elseif requestArray[1] == "register" then
            print("Register " .. requestArray[2] .. " " .. requestArray[3] .. " " .. requestArray[4])
            registerResult = registerDomain(requestArray[2], requestArray[3], requestArray[4], requestArray[5])
            print("Register Result: " .. registerResult)
            sleep(0.1)
            rednet.send(sender, sender .. "<#>" .. registerResult)
        elseif requestArray[1] == "modify" then
            result = modifyDomain(requestArray[2], requestArray[3], requestArray[4], requestArray[5])
            sleep(0.1)
            rednet.send(sender, sender .. "<#>" .. result)

        elseif requestArray[1] == "delete" then
            result = deleteDomain(requestArray[2], requestArray[3])
            sleep(0.1)
            rednet.send(sender, sender .. "<#>" .. result)
        end
    end
end