require "socket"

local sv=socket.bind("*",7775)
local cl=sv:accept()
local tsv=socket.connect("127.0.0.1",7777)
local c
do
    local str_byte=string.byte
    local str_char=string.char
    local str_len=string.len
    local str_sub=string.sub
    local m_floor=math.floor
    function c(txt)
        local o=0
        local s={str_byte(txt,1,4)}
        o=o+s[1]
        o=o+(s[2]*256)
        o=o+(s[3]*65536)
        o=o+(s[4]*16777216)
        return o
    end
end
local sl={cl,tsv}
local so_sel=socket.select
local stm=cl.settimeout
local rec=cl.receive
local snd=cl.send
local ts,te,cs
while true do
    stm(cl,0)
    local s,e=rec(cl,4)
    if s then
        stm(cl)
        ts,te=rec(cl,c(s))
        snd(tsv,s..ts)
    end
    stm(tsv,0)
    local s,e=rec(tsv,4)
    if s then
        stm(tsv)
        ts,te=rec(tsv,c(s))
        snd(cl,s..ts)
    end
    so_sel(sl,nil,0.1)
end