#include <sys/socket.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/un.h>
#include <sys/time.h>
#include <unistd.h>
#include <netinet/in.h>
#include <netdb.h>
#define NTP_PORT 123
#define TIME_PORT 37
#define NTP_SERVER_IP "211.68.71.26"
#define NTP_PORT_STR "123"
#define NTPV1 "NTP/V1"
#define NTPV2 "NTP/V2"
#define NTPV3 "NTP/V3"
#define NTPV4 "NTP/V4"
#define TIME "TIME/UDP"
#define NTP_PCK_LEN 48
#define LI 0
#define VN 3
#define MODE 3
#define STRATUM 1
#define POLL 4
#define PREC -6
#define JAN_1970 0x83aa7e80
#define NTPFRAC(x) (4294*(x)+((1981*(x)>>11)))
#define USEC(x) (((x)>>12)-759*((((x)>>10)+32768)>>16))
typedef struct _ntp_time
{
unsigned int coarse;
unsigned int fine;
}ntp_time;
struct ntp_packet
{
unsigned char leap_ver_mode;
unsigned char startum;
char poll;
char precision;
int root_delay;
int root_dispersion;
int reference_identifier;
ntp_time reference_timestamp;
ntp_time originage_timestamp;
ntp_time receive_timestamp;
ntp_time transmit_timestamp;
};
char protocol[32];
/*构建NTP协议包*/
int construct_packet(char *packet)
{
char version = 1;
long tmp_wrd;
int port;
time_t timer;
strcpy(protocol,NTPV3);
/*判断协议版本*/
if(!strcmp(protocol,NTPV1)||!strcmp(protocol,NTPV2)
||!strcmp(protocol,NTPV3)||!strcmp(protocol,NTPV4))
{
memset(packet,0,NTP_PCK_LEN);
port = NTP_PORT;
/* 设置16字节的包头 */
version = protocol[5]-0x30;
// printf("\r\n version%d,protocol%d",version,protocol[6]);
tmp_wrd = htonl((LI <<30)|(version << 27)
|(MODE << 24)|(STRATUM <<16)|(POLL << 8)|(PREC & 0xff));
memcpy(packet,&tmp_wrd,sizeof(tmp_wrd));
// printf("\r\n tmp_wrd=%x",tmp_wrd);
/*设置 Root Delay, Root Dispersion和Reference Indentifier*/
tmp_wrd = htonl(1<<16);
memcpy(&packet[4],&tmp_wrd,sizeof(tmp_wrd));
memcpy(&packet[8],&tmp_wrd,sizeof(tmp_wrd));
/*设置Timestamp部分*/
time(&timer);
/* 设置 Transmit Timestamp coarse*/
tmp_wrd = htonl(JAN_1970+(long)timer);
memcpy(&packet[40],&tmp_wrd,sizeof(tmp_wrd));
/*设置 Transmit Timestamp fine */
tmp_wrd = htonl(JAN_1970+(long)timer);
memcpy(&packet[44],&tmp_wrd,sizeof(tmp_wrd));
return NTP_PCK_LEN;
}
else if (!strcmp(protocol,TIME))
{
port = TIME_PORT;
memset(packet,0,4);
return 4;
}
return 0;
}
int get_ntp_time(int sk,struct addrinfo *addr,struct ntp_packet *ret_time)
{
int iret=0;
fd_set pending_data;
struct timeval block_time;
char data[NTP_PCK_LEN*8];
int packet_len,data_len=addr->ai_addrlen,count = 0,result,i,re;
memset(data,'\0',sizeof(data));
if(!(packet_len = construct_packet(data)))
{
printf("\r\n construct packet fail");
return 0;
}
/*客户端给服务器发送NTP协议数据包*/
for (iret = 0;iret<48;iret++)
{
// printf(" data[%d] = %d",iret,data[iret]);
}
// printf("\r\n sk=%d,packetlen=%d, datalen=%d",sk,packet_len,data_len);
if ((result = sendto(sk,data,packet_len,0,addr->ai_addr,data_len))<0)
{
perror("sendto");
printf("\r\n sendto fail");
return 0;
}
printf("\r\n sendto result %d",result);
/*调用select()函数,并设定超时时间为1s*/
FD_ZERO(&pending_data);
FD_SET(sk,&pending_data);
block_time.tv_sec = 10;
block_time.tv_usec = 0;
if ((iret=select(sk+1,&pending_data,NULL,NULL,&block_time))>0)
{
/*接收服务器端的信息*/
if((count = recvfrom(sk,data,NTP_PCK_LEN*8,0,addr->ai_addr,&data_len))<0)
{
perror("recvfrom");
printf("\r\n recvfrom fail");
return 0;
}
if (protocol == TIME)
{
memcpy(&ret_time->transmit_timestamp,data,4);
return 1;
}
else if (count < NTP_PCK_LEN)
{
printf("\r\n count fail");
return 0;
}
/*设置接收NTP包的数据结构*/
ret_time->leap_ver_mode = ntohl(data[0]);
ret_time->startum = ntohl(data[1]);
ret_time->poll = ntohl(data[2]);
ret_time->precision = ntohl(data[3]);
ret_time->root_delay = ntohl(*(int*)&(data[4]));
ret_time->root_dispersion = ntohl(*(int*)&(data[8]));
ret_time->reference_identifier = ntohl(*(int*)&(data[12]));
ret_time->reference_timestamp.coarse = ntohl(*(int*)&(data[16]));
ret_time->reference_timestamp.fine = ntohl(*(int*)&(data[20]));
ret_time->originage_timestamp.coarse = ntohl(*(int*)&(data[24]));
ret_time->originage_timestamp.fine = ntohl(*(int*)&(data[28]));
ret_time->receive_timestamp.coarse = ntohl(*(int*)&(data[32]));
ret_time->receive_timestamp.fine = ntohl(*(int*)&(data[36]));
ret_time->transmit_timestamp.coarse = ntohl(*(int*)&(data[40]));
ret_time->transmit_timestamp.fine = ntohl(*(int*)&(data[44]));
return 1;
}
printf("\r\n select fail=0x%x",iret);
return 0;
}
/*修改本地时间*/
int set_local_time(struct ntp_packet* pnew_time_packet)
{
struct timeval tv;
tv.tv_sec = pnew_time_packet->transmit_timestamp.coarse-JAN_1970;
tv.tv_usec = USEC(pnew_time_packet->transmit_timestamp.fine);
return settimeofday(&tv,NULL);
}
int main()
{
int sockfd,rc;
struct addrinfo hints,*res = NULL;
struct ntp_packet new_time_packet;
memset(&hints,0,sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = IPPROTO_UDP;
// printf("start main");
rc = getaddrinfo(NTP_SERVER_IP,NTP_PORT_STR,&hints,&res);
if (rc != 0)
{
perror("getaddrinfo");
return 1;
}
// printf("\r\n res->ai_family=%x,res->ai_socktype=%x,res->ai_protocol=%x",res->ai_family,res->ai_socktype,res->ai_protocol);
// printf("\r\n hints.aifamily=%x,hints.ai_socktype=%x,hints.ai_protocol=%x",hints.ai_family,hints.ai_socktype,hints.ai_protocol);
// printf("\r\naf_inet=%d af_inet6=%d af_unspec=%d",AF_INET,AF_INET6,AF_UNSPEC);
// sockfd = socket(res->ai_family,res->ai_socktype,res->ai_protocol);
sockfd = socket(res->ai_family,res->ai_socktype,0);
if (sockfd < 0)
{
perror("socket");
return 1;
}
/*调用取得NTP时间函数*/
if (get_ntp_time(sockfd,res,&new_time_packet))
{
int iret = 0;
/*调整本地时间*/
iret = set_local_time(&new_time_packet);
if (!iret)
{
printf("NTP client success!\n");
}
else
{
printf("\r\nset local fail =%d",iret);
}
}
else
{
printf("\r\n get ntp time fail");
}
close(sockfd);
printf("\r\n end main\r\n");
return 0;
}