ntp网络时间协议-封装库

#include <sys/types.h> #include <sys/socket.h> #include <netdb.h> #include <netinet/in.h> #include <arpa/inet.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <time.h> #include "NtpClientFunc.h" // //rfc1305 defined from 1900 so also 2208988800 (1900 - 1970 ) seconds left // //timeval.tv_sec + JAN_1970 = timestamp.coarse #define JAN_1970 0x83aa7e80 //timeval.tv_usec=>timestamp.fine #define NTPFRAC(x) (4294 * (x) + ((1981 * (x))>>11)) //timeval.tv_usec<=timestamp.fine #define USEC(x) (((x) >> 12) - 759 * ((((x) >> 10) + 32768) >> 16)) //创建本地UDPsocket int CreateNtpClientSockfd() { int sockfd; int addr_len; struct sockaddr_in addr_src; int ret; addr_len = sizeof(struct sockaddr_in); memset(&addr_src, 0, addr_len); addr_src.sin_family = AF_INET; addr_src.sin_addr.s_addr = htonl(INADDR_ANY); addr_src.sin_port = htons(0); /* create socket. */ if(-1==(sockfd = socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP))) { printf("create socket error!\n"); return -1; } /* bind local address. */ ret = bind(sockfd, (struct sockaddr*)&addr_src, addr_len); if(-1==ret) { printf("bind error!\n"); close(sockfd); return -1; } return sockfd; } //链接到NTP服务器 int ConnectNtpServer(int sockfd,char * serverAddr, int serverPort, struct sockaddr_in * ServerSocket_in) { int addr_len; struct sockaddr_in addr_dst; struct hostent* host; int ret; addr_len = sizeof(struct sockaddr_in); memset(&addr_dst, 0, addr_len); addr_dst.sin_family = AF_INET; host = gethostbyname(serverAddr); memcpy(&(addr_dst.sin_addr.s_addr), host->h_addr_list[0], 4); addr_dst.sin_port = htons(serverPort); memcpy(ServerSocket_in,&addr_dst,sizeof(struct sockaddr_in)); /* connect to ntp server. */ ret = connect(sockfd, (struct sockaddr*)&addr_dst, addr_len); if(-1==ret) { printf("connect error!\n"); close(sockfd); return -1; } return sockfd; } //发送ntp请求包，请求服务器的返回时间, sockfd为socket文件描述符,为 poll_intervals 测试间隔 void SendQueryTimePacked(int sockfd) { NTPPACKED SynNtpPacked; struct timeval now; memset(&SynNtpPacked, 0, sizeof(SynNtpPacked)); SynNtpPacked.header.local_precision = -6; SynNtpPacked.header.Poll = 4; SynNtpPacked.header.stratum = 0; SynNtpPacked.header.Mode = 3; SynNtpPacked.header.VN = 3; SynNtpPacked.header.LI = 0; SynNtpPacked.root_delay = 1<<16; /* Root Delay (seconds) */ SynNtpPacked.root_dispersion = 1<<16; /* Root Dispersion (seconds) */ SynNtpPacked.header.headData = htonl(SynNtpPacked.header.headData); SynNtpPacked.root_delay = htonl(SynNtpPacked.root_dispersion); SynNtpPacked.root_dispersion = htonl(SynNtpPacked.root_dispersion); gettimeofday(&now, NULL); /* get current local_time*/ SynNtpPacked.trantime.coarse = htonl(now.tv_sec + JAN_1970); /* Transmit Timestamp coarse */ SynNtpPacked.trantime.fine = htonl(NTPFRAC(now.tv_usec)); /* Transmit Timestamp fine */ send(sockfd, &SynNtpPacked, sizeof(SynNtpPacked), 0); } //从服务器接收数据包 int RecvNtpPacked(int sockfd,PNTPPACKED pSynNtpPacked,struct sockaddr_in * ServerSocket_in) { int receivebytes; int addr_len = sizeof(struct sockaddr_in); /* recv ntp server's response. */ receivebytes = recvfrom(sockfd, pSynNtpPacked, sizeof(NTPPACKED), 0, (struct sockaddr *)ServerSocket_in, &addr_len); if(-1==receivebytes) { printf("recvfrom error\n"); close(sockfd); return -1; } return receivebytes; } //从ntp服务器返回的数据包中解析出新的时间,pSynNtpPacked为server返回给client的数据包，new_time为解析出时间 void GetSynTimeFromNtpPacked(PNTPPACKED pSynNtpPacked,struct timeval* new_time) { NTPTIME trantime; trantime.coarse = ntohl(pSynNtpPacked->trantime.coarse); trantime.fine = ntohl(pSynNtpPacked->trantime.fine); new_time->tv_sec = trantime.coarse - JAN_1970; new_time->tv_usec = USEC(trantime.fine); } //修改本地linux时间 void ModifyLocalTime(struct timeval* new_time) { /* need root user. */ if (0 != getuid() && 0 != geteuid()) { printf(">>>>>not Modify localtime , you must be root user!)\n"); return; } settimeofday(new_time, NULL); } //关闭Socked句柄 void CloseSockfd(int sockfd) { close(sockfd); }