Lua获取网络时间（获取时间同步服务器的时间）

2024-07-21 23:04:31

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网络授时服务是一些网络上的时间服务器提供的时间，一般用于本地时钟同步。授时服务有很多种，一般我们选择RFC-868。这个协议的工作流程是：（S代表Server，C代表Client）

S: 检测端口37
U: 连接到端口37
S: 以32位二进制数发送时间
U: 接收时间
U: 关闭连接
S: 关闭连接
协议非常简单，用TCP连接上后，服务器直接把时间发送回来。发送的是从1900年1月1日午夜到现在的秒数。

使用luasocket
实现的方案有很多种，Lua不一定是最简单的，选择只是出于个人兴趣。直接上代码吧

------------------------------------------------------------------------------- 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 nend-- get time from a ip address, use tcp protoclfunction gettime(ip)  print('connect ', ip)  local tcp = socket.tcp()  tcp:settimeout(10)  tcp:connect(ip, 37)  success, time = pcall(nstol, tcp:receive(4))  tcp:close()  return success and time or nilendfunction nettime()  for _, ip in pairs(server_ip) do    time = gettime(ip)    if time then       return time    end  endend

代码原理不细说，非常简单。唯一值得一提的是socket库包含。最开始用的这句 require "socket"

在解释器中表现很好，但在用C中调用会找不到相应的module。错误提示

  no field package.preload['socket']  no file './socket.lua'  no file 'F:/Projects/Lua/nettime/lua/socket.lua'  no file 'F:/Projects/Lua/nettime/lua/socket/init.lua'  no file 'F:/Projects/Lua/nettime/socket.lua'  no file 'F:/Projects/Lua/nettime/socket/init.lua'  no file 'D:/tools/Lua/5.1/lua/socket.luac'  no file './socket.dll'  no file './socket51.dll'  no file 'F:/Projects/Lua/nettime/socket.dll'  no file 'F:/Projects/Lua/nettime/socket51.dll'  no file 'F:/Projects/Lua/nettime/clibs/socket.dll'  no file 'F:/Projects/Lua/nettime/clibs/socket51.dll'  no file 'F:/Projects/Lua/nettime/loadall.dll'  no file 'F:/Projects/Lua/nettime/clibs/loadall.dll'.

网上也有好多类似的提问，大抵是没仔细看作者的Guide。显著的有这么一句

The other two environment variables instruct the compatibility module to look for dynamic libraries and extension modules in the appropriate directories and with the appropriate filename extensions.>

LUAPATH=/?.lua;?.lua LUACPATH=/?.dll;?.dll

至于"socket.core"，windows默认安装位于“/socket/core.dll”。

C宿主调用

#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;}

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