Linux下Ping的实现代码

#include <stdio.h> #include <sys/socket.h> #include <netinet/in.h> #include <netinet/ip.h> #include <netinet/ip_icmp.h> #include <netdb.h> #define PACKET_SIZE 4096 #define ERROR 0 #define SUCCESS 1 // 效验算法 unsigned short cal_chksum(unsigned short *addr, int len) { int nleft=len; int sum=0; unsigned short *w=addr; unsigned short answer=0; while(nleft > 1) { sum += *w++; nleft -= 2; } if( nleft == 1) { *(unsigned char *)(&answer) = *(unsigned char *)w; sum += answer; } sum = (sum >> 16) + (sum & 0xffff); sum += (sum >> 16); answer = ~sum; return answer; } // Ping函数 int ping( char *ips, int timeout) { struct timeval timeo; int sockfd; struct sockaddr_in addr; struct sockaddr_in from; struct timeval *tval; struct ip *iph; struct icmp *icmp; char sendpacket[PACKET_SIZE]; char recvpacket[PACKET_SIZE]; int n; pid_t pid; int maxfds = 0; fd_set readfds; // 设定Ip信息 bzero(&addr,sizeof(addr)); addr.sin_family = AF_INET; addr.sin_addr.s_addr = inet_addr(ips); // 取得socket sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); if (sockfd < 0) { syslog(LOG_INFO,"ip:%s,socket error",ips); return ERROR; } // 设定TimeOut时间 timeo.tv_sec = timeout / 1000; timeo.tv_usec = timeout % 1000; if (setsockopt(sockfd, SOL_SOCKET, SO_SNDTIMEO, &timeo, sizeof(timeo)) == -1) { syslog(LOG_INFO,"ip:%s,setsockopt error",ips); return ERROR; } // 设定Ping包 memset(sendpacket, 0, sizeof(sendpacket)); // 取得PID，作为Ping的Sequence ID pid=getpid(); int i,packsize; icmp=(struct icmp*)sendpacket; icmp->icmp_type=ICMP_ECHO; icmp->icmp_code=0; icmp->icmp_cksum=0; icmp->icmp_seq=0; icmp->icmp_id=pid; packsize=8+56; tval= (struct timeval *)icmp->icmp_data; gettimeofday(tval,NULL); icmp->icmp_cksum=cal_chksum((unsigned short *)icmp,packsize); // 发包 n = sendto(sockfd, (char *)&sendpacket, packsize, 0, (struct sockaddr *)&addr, sizeof(addr)); if (n < 1) { syslog(LOG_INFO,"ip:%s,sendto error",ips); return ERROR; } // 接受 // 由于可能接受到其他Ping的应答消息，所以这里要用循环 while(1) { // 设定TimeOut时间，这次才是真正起作用的 FD_ZERO(&readfds); FD_SET(sockfd, &readfds); maxfds = sockfd + 1; n = select(maxfds, &readfds, NULL, NULL, &timeo); if (n <= 0) { syslog(LOG_INFO,"ip:%s,Time out error",ips); close(sockfd); return ERROR; } // 接受 memset(recvpacket, 0, sizeof(recvpacket)); int fromlen = sizeof(from); n = recvfrom(sockfd, recvpacket, sizeof(recvpacket), 0, (struct sockaddr *)&from, &fromlen); if (n < 1) { break; } // 判断是否是自己Ping的回复 char *from_ip = (char *)inet_ntoa(from.sin_addr); syslog(LOG_INFO,"fomr ip:%s",from_ip); if (strcmp(from_ip,ips) != 0) { syslog(LOG_INFO,"ip:%s,Ip wang",ips); break; } iph = (struct ip *)recvpacket; icmp=(struct icmp *)(recvpacket + (iph->ip_hl<<2)); syslog(LOG_INFO,"ip:%s,icmp->icmp_type:%d,icmp->icmp_id:%d",ips,icmp->icmp_type,icmp->icmp_id); // 判断Ping回复包的状态 if (icmp->icmp_type == ICMP_ECHOREPLY && icmp->icmp_id == pid) { // 正常就退出循环 break; } else { // 否则继续等 continue; } } // 关闭socket close(sockfd); syslog(LOG_INFO,"ip:%s,Success",ips); return SUCCESS; }