Lua网络校时

gistfile1.c

#include <stdio.h>
#include <string.h>
#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>
#include <time.h>
#include <Windows.h>

int load(lua_State* L, const char* func, unsigned int* utc) {
   lua_getglobal(L, func);
   if (lua_pcall(L, 0, 1, 0)) {
        printf("Error Msg pcall %s.\n", lua_tostring(L, -1));
        return -1;
   }

   if (!lua_isnumber(L,-1)) {
       printf("time should be a number\n" );
       return -2;
   }

   *utc = lua_tonumber(L,-1);
   lua_pop(L, -1);
   return 0;
}

void TimetToFileTime( time_t t, LPFILETIME pft )
{
    LONGLONG ll = Int32x32To64(t, 10000000) + 116444736000000000;
    pft->dwLowDateTime = (DWORD) ll;
    pft->dwHighDateTime = ll >>32;
}

int main()
{
   lua_State* L = luaL_newstate();
   unsigned int utc = 0;
   luaL_openlibs(L);
  if (luaL_loadfile(L, "nettime.lua") || lua_pcall(L, 0, 0, 0)) {
       printf("Error Msg load %s.\n", lua_tostring(L, -1));
       return -1;
   }
   do {
    if(load(L,"nettime", &utc) == 0) {
        time_t tt = utc - 2208988800L;
        SYSTEMTIME st;
        FILETIME ft;
        TimetToFileTime(tt, &ft);
        if (FileTimeToSystemTime(&ft, &st))
        {
            printf("Today is: %d-%d-%d\n", st.wYear, st.wMonth, st.wDay);
            SetSystemTime(&st);
        }
        break;
    } else {
        puts("No network!");
        Sleep(10000);
    }
   } while (1);
   lua_close(L);
   return 0;
}

nettime.lua

-----------------------------------------------------------------------------
-- Network Time Protocal
-- Author: ani di
-----------------------------------------------------------------------------
package.cpath = package.cpath .. ';D:\\tools\\Lua\\5.1\\clibs\\?.dll;?.dll'
local socket = require "socket.core"

server_ip = {
		-- "129.6.15.29",
		"132.163.4.101",
		"132.163.4.102",
		"132.163.4.103",
		"128.138.140.44",
		"192.43.244.18",
		"131.107.1.10",
		"66.243.43.21",
		"216.200.93.8",
		"208.184.49.9",
		"207.126.98.204",
		"207.200.81.113",
		"205.188.185.33"}
		
function nstol(str)
	assert(str and #str == 4)
    local t = {str:byte(1,-1)}
    local n = 0
    for k = 1, #t do
        n= n*256 + t[k]
    end
    return n
end

-- get time from a ip address, use tcp protocl
function gettime(ip)
	print('connect ', ip)
	local tcp = socket.tcp()
	tcp:settimeout(10)
	tcp:connect(ip, 37)
	success, time = pcall(nstol, tcp:receive(4)) -- 32bit return
	tcp:close()
	return success and time or nil
end

function nettime()
	for _, ip in pairs(server_ip) do
		time = gettime(ip)
		if time then 
			return time
		end
	end
end