WinSock网络编程经络- 简单网络时间协议客户端程序

WinSock网络编程经络- 简单网络时间协议客户端程序简单网络时间协议客户端程序
/*************************************************************************
*
* Copyright (c) 2002-2005 by Zhang Huiyong All Rights Reserved
*
* FILENAME: SntpClnt.c
*
* PURPOSE : 简单网络时间协议客户端程序.
*
* AUTHOR : 张会勇
*
* BOOK : <<WinSock网络编程经络>>
*
**************************************************************************/
#include <winsock2.h>
#include <ws2tcpip.h> /* struct ip_mreq */
#include <stdio.h>
#include "Sntp.h"
#pragma comment(lib, "ws2_32.lib") /* WinSock使用的库函数*/
/************************************************************************** *
* 函数功能: 处理从服务器接收到的消息.
*
* 参数说明: [IN] sntp_msg, SNTP 消息;
* [IN] msg_len, 消息缓冲区长度;
* [IN] dest_t, 接收时间;
*
* 返回值: 成功返回0, 失败返回-1.
*
**************************************************************************/ static int sntp_recv_handle(struct sntp_s *sntp_msg, int msg_len,
time_fp *dest_t)
{
double diff;
unsigned char mode;
time_fp t2_1, t3_4;
time_fp offset_t, orig_t, recv_t, xmt_t;
/* 检查SNTP 消息的有效性*/
if (msg_len < sizeof(*sntp_msg))
{
printf("[SNTP] packet is too small %d\n", msg_len);
return -1;
}
if (MSG_VERSION(sntp_msg->li_vn_md) < SNTP_OLD_VERSION || MSG_VERSION(sntp_msg->li_vn_md) > SNTP_VERSION) {
printf("[SNTP] version is wrong\n");
return -1;
}
mode = MSG_MODE(sntp_msg->li_vn_md);
if (mode != MODE_SERVER && mode != MODE_BROADCAST) {
printf("[SNTP] mode is not matched %d\n", mode);
return -1;
}
NTOHL_FP(&sntp_msg->orig, &orig_t);
NTOHL_FP(&sntp_msg->recv, &recv_t); NTOHL_FP(&sntp_msg->xmt, &xmt_t);
/* 没有本机的Transmit Timestamp */
if (orig_t.fp_ui == 0 && orig_t.fp_uf == 0)
{
offset_t = xmt_t;
TS_SUB(&offset_t, dest_t);
}
else
{
/* 计算时钟偏差: ((T2 - T1) + (T3 - T4)) / 2 */ t3_4 = xmt_t;
TS_SUB(&t3_4, dest_t); /* T3 - T4 */
t2_1 = recv_t;
TS_SUB(&t2_1, &orig_t);
offset_t = t3_4;
TS_RSHIFT(&offset_t);
TS_RSHIFT(&t2_1);
TS_ADD(&offset_t, &t2_1);
}
TS_FPTOD(&offset_t, diff);
printf("[SNTP] offset with the server is : %d microsecond\n", (int)(diff * 1000000));
return 0;
}
int main(int argc, char **argv)
{
WSADATA wsa_data;
SOCKET clt_soc = 0; /* 客户端socket句柄*/
struct ip_mreq mcast_addr; /* 多播地址*/
struct sockaddr_in local, dest;
unsigned short port = SNTP_DEF_PORT;
int result, addr_len = sizeof(local);
struct sntp_s sntp_msg;
time_fp now_fp;
char *srv_addr = NULL;
if (argc > 1)
srv_addr = argv[1];
WSAStartup(WINSOCK_VERSION, &wsa_data); /* 初始化WinSock 资源*/ clt_soc = socket(AF_INET, SOCK_DGRAM, 0);/* 创建SNTP 的socket */
local.sin_family = AF_INET;
local.sin_port = htons(port);
local.sin_addr.s_addr = INADDR_ANY;
result = bind(clt_soc, (struct sockaddr *)&local, sizeof(local));
if (result == SOCKET_ERROR)
{
printf("[SNTP] bind() error : %d\n", WSAGetLastError());
closesocket(clt_soc);
return -1;
}
/* 多播地址*/
mcast_addr.imr_multiaddr.s_addr = inet_addr(SNTP_MCAST_ADDR);
mcast_addr.imr_interface.s_addr = INADDR_ANY;
/* 加入多播组*/
result = setsockopt(clt_soc, IPPROTO_IP, IP_ADD_MEMBERSHIP,
(char *)&mcast_addr, sizeof(mcast_addr));
if (result == SOCKET_ERROR)
{
printf("[SNTP] setsockopt(IP_ADD_MEMBERSHIP) error : %d\n", WSAGetLastError());
closesocket(clt_soc);
return -1;
}
memset(&sntp_msg, 0, sizeof(sntp_msg));
sntp_get_sys_time(&sntp_msg.xmt);
HTONL_FP(&sntp_msg.xmt, &sntp_msg.xmt);
sntp_msg.li_vn_md = MSG_LI_VN_MODE(LEAP_NOT_SYNC,
SNTP_VERSION, MODE_CLIENT);
if (srv_addr)
{
dest.sin_family = AF_INET;
dest.sin_port = htons((u_short)(port + 1));
dest.sin_addr.s_addr = inet_addr(srv_addr);
if (dest.sin_addr.s_addr != INADDR_NONE) /* 发送单播数据报*/ sendto(clt_soc, (char *)&sntp_msg, sizeof(sntp_msg), 0,
(struct sockaddr *)&dest, sizeof(dest));
}
printf("[SNTP] is sychronizing ... ...\n");
while (1)
{
memset(&sntp_msg, 0, sizeof(sntp_msg));
result = recvfrom(clt_soc, (char *)&sntp_msg, sizeof(sntp_msg),
0, (struct sockaddr *)&dest, &addr_len);
if (result == SOCKET_ERROR)
{
printf("[SNTP] recvfrom() error : %d\n", WSAGetLastError());
break;
}
sntp_get_sys_time(&now_fp);
sntp_recv_handle(&sntp_msg, result, &now_fp);
}
/* 离开多播组*/
result = setsockopt(clt_soc, IPPROTO_IP, IP_DROP_MEMBERSHIP,
(char *)&mcast_addr, sizeof(mcast_addr));
closesocket(clt_soc);
WSACleanup();
return 0;
}
得到系统当前时间
/*************************************************************************
*
* Copyright (c) 2002-2005 by Zhang Huiyong All Rights Reserved
*
* FILENAME: SntpUtil.c
*
* PURPOSE : 得到系统当前时间.
*
* AUTHOR : 张会勇
*
* BOOK : <<WinSock网络编程经络>>
*
**************************************************************************/
#include <Windows.h>
#include <time.h>
#include "Sntp.h"
/************************************************************************** *
* 函数功能: 得到系统当前时间.
*
* 参数说明: [OUT] current, SNTP 时间.
*
* 返回值: 成功返回0, 失败返回-1.
*
**************************************************************************/ int sntp_get_sys_time(time_fp *current)
{
double temp_d;
time_t second;
long nano_sec;
union {
FILETIME ft;
ULONGLONG ull;
} ft_now;
if (current == NULL)
return -1;
GetSystemTimeAsFileTime(&ft_now.ft);
/* 把hecto-nano second 转换成second 和nanosecond */
ft_now.ull -= SNTP_TIME_1900;
second = (time_t)(ft_now.ull / SNTP_HECTO_NANOSECONDS);
nano_sec = (long)((ft_now.ull % SNTP_HECTO_NANOSECONDS) * 100);
/* 转换成NTP Timestamp 格式*/
current->fp_si = second;
temp_d = nano_sec * 1e-9; /* 转换成second */
if (temp_d >= 1.0)
{
temp_d -= 1.0;
current->fp_si++;
}
else if (temp_d < 0)
{
temp_d += 1.0;
current->fp_si--;
}
current->fp_uf = (unsigned int)(temp_d * SNTP_TS_FRAC);
return 0;
}。