vision/src/metaserver/main.lua

--Note, this won't work unless you set up port forwarding!
local SERVERTIMEOUT = 30
local CLIENTTIMEOUT = 1

local shared = assert( require '../shared.shared' )
local socket = assert( require 'socket' )
local packet = assert( shared.packet )
local udp = assert( socket.udp() )
local msip = assert( require 'getip' )
udp:settimeout(0)
local localIP = socket.dns.toip(socket.dns.gethostname())
print( "Metaserver local IP:", localIP )
assert( udp:setsockname( localIP, shared.metaserver.port ))

--Servers broadcast their information here.
--The metaserver builds a list of available servers. ( available meaning, "broadcasted in last ten heartbeats" )
--Clients ask the metaserver for this list ( maybe with some filter? )
local servers = {}
local clients = {}
local tick = 0

local handlers = setmetatable({

    serverInfo = function( svInfo, ip, port )
      print( "Server:", ip, port )
      local t = socket.gettime()
      if not servers[ip..port] then
        servers[ip..port] = { ip = ip, port = port, info = svInfo }
        --NAT punch: the server doesn't know its own external IP
        --so it contacts a third party (the metaserver) to discover it.
        --This external IP gets advertised to prospective clients.
        svInfo.ip.ip = ip
        svInfo.port = port
      end
      servers[ip..port].time = t
      packet.advertised{ time = t, ip = svInfo.ip, port = svInfo.port }
      return udp:sendto( packet.get(), ip, port )
    end,
    
    default = function( s, ip, port )
      print( ip, port, "Malformed message: ", s )
    end,

    metaServer = function()

    end,

    clientInfo = function( clientInfo, ip, port )
      --[[if ip ~= tostring( clientInfo.ip ) then 
        return print( ip, port, "Client IP mismatch:", clientInfo.ip )
      end]]
      
      print( "Server List:", ip, port )
      
      clients[ip] = clients[ip] or {}
      
      local t = socket.gettime()
      clients[ip].time = t

      for svIP, server in pairs( servers ) do
        print( "", svIP, packet.getString( server.info.svname ))
        packet.serverInfo( server.info )
      end
      
      return udp:sendto( packet.get(), ip, port )
    end
  },

  {
    __index = function(t) return t.default end
  })

local function read(msg, ip, port)
  if not msg then return end
  local msgs, types = packet.deserialise( msg )
  if types[1] ~= "metaServer" then 
    print( ip, port, "Dropped packet, no padding." )
    return read( udp:receivefrom() )
  end
  for i = 1, #msgs do
    handlers[ types[i] ]( msgs[i], ip, port )
  end
  return read( udp:receivefrom() )
end

local function prune( t )
  for ip, server in pairs(servers) do
    if server.time < t - SERVERTIMEOUT then
      print( "Pruning server IP:", ip )
      servers[ip] = nil
    end
  end
end

print( "Starting Metaserver", os.time(), udp:getsockname() )
function love.update()
  read( udp:receivefrom() )
  prune( socket.gettime() )
  io.flush()
  tick = tick + 1
end