ocvn/lib/dhcp.lua

local net = require("net")
local fs = require("filesystem")
local io = require("io")
local serial = require("serialization")

local dhcp = {
  SERV_PORT = 67,
  CLIENT_PORT = 68,
  CONFIG_FILE = "/etc/dhcp/config"
}

-- Local function for creating directory
function createConfigDir(fileName)
  local configsExist = true
  local dir = fs.path(fileName)
  
  if fs.exists(dir) and not fs.isDirectory(dir) then
    fs.remove(dir)
  end
  
  if not fs.exists(dir) then
    fs.makeDirectory(dir)
    return true
  end
  return false
end

-- Gets an existing server config or creates one if it doesn't exist
function dhcp.getServerConfig(fileName)
  
  if fileName == nil then fileName = dhcp.CONFIG_FILE end
  
  local configsExist = true
  
  if not createConfigDir(fileName) then
    if fs.isDirectory(fileName) then
      fs.remove(fileName)
    end
    
    if not fs.exists(fileName) then
      configsExist = false
    end
  else
    configsExist = false
  end
  
  if not configsExist then
    print("Creating config since one doesn't exist")
    local f = io.open(fileName, "w")
    config = {dns = "", pxe = ""}
    f:write(serial.serialize(config, 5))
    f:close()
    return config
  else
    f = io.open(fileName, "r")
    local data = ""
    while true  do
      local line = f:read()
      if line ~= nil then
        data = data..line
      else
        break
      end
    end
    f:close()
    return serial.unserialize(data)
  end
end

function dhcp.startServer(servPort, clientPort, nonblocking, cacheConfig)
  -- Make sure ports aren't invalid
  if type(servPort) ~= "number" then
    servPort = dhcp.SERV_PORT
  end
  
  if type(clientPort) ~= "number" then
    clientPort = dhcp.CLIENT_PORT
  end
  
  -- Filter function for getting dhcp server messages
  function dhcp.serverMsg(name, ...)
    local t = {...}
    
    if t[3] == servPort and
       t[5] == "dhcp" and
       t[6] == clientPort and
       t[7] == "get" then
      return true
    end
    return false
  end
  
  print("Starting up DHCP server")
  
  if cacheConfig == nil then
    cacheConfig = true
  else
    cacheConfig = false
  end
  
  -- Read from config file each time, or just read once and use that for life of execution
  local config = dhcp.getServerConfig()
    
  while true do
    local pkt, err = net.recv{servPort, filter = dhcp.serverMsg, nonblocking = nonblocking}

    if pkt == nil and err == "interrupted" then
      print("Interrupted")
      return pkt, err
    end

    print("Received request from "..pkt.raddr)
    if cacheConfig then
      net.send(pkt.raddr, clientPort, "dhcp", serial.serialize(config))
    else
      print("Here")
      net.send(pkt.raddr, clientPort, "dhcp", serial.serialize(dhcp.getServerConfig()))
    end

  end
end

function dhcp.query(servPort, clientPort, nonblocking)
  -- Make sure ports aren't invalid
  if type(servPort) ~= "number" then
    servPort = dhcp.SERV_PORT
  end
  
  if type(clientPort) ~= "number" then
    clientPort = dhcp.CLIENT_PORT
  end
  
  -- Filter function for getting dhcp client messages
  function dhcp.clientMsg(name, ...)
    local t = {...}
    
    if t[3] ~= clientPort or t[5] ~= "dhcp" then
      return false
    elseif type(t[6]) ~= "string" then
      return false
    elseif serial.unserialize(t[6]) == nil then
      return false
    else
      return true
    end
  end

  net.broadcast(servPort, "dhcp", clientPort, "get")
  pkt, err = net.recv{
    clientPort,
    timeout = 3,
    filter = dhcp.clientMsg,
    nonblocking = not not nonblocking
  }
  return pkt, err
end

-- wget -f http://mc.bashed.rocks:13699/lib/dhcp.lua lib/dhcp.lua

return dhcp