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//http://blog.chinaunix.net/uid-25909722-id-2762079.html#include#include #include #include /* for bzero */#include #include #include #include #include #include #include #include #include #include #include #include #define MAX_WAIT_TIME 5#define PACKET_SIZE 4096 /* 数据包的大小 */#define MAX_NO_PACKETS 3 /* 发送3个ICMP报文 */char sendpacket[PACKET_SIZE]; /* 发送的数据包 */char recvpacket[PACKET_SIZE]; /* 接收的数据包 */pid_t pid;int sockfd;int datalen = 56; /* icmp数据包中数据的长度 */int nsend = 0; /* 发送的次数 */int nreceived = 0; /* 接收的次数 */struct sockaddr_in dest_addr; /* icmp包目的地址 */struct sockaddr_in from; /* icmp包源地址 */struct timeval tvrecv;void statistics(int signo);unsigned short cal_chksum(unsigned short *addr,int len);int pack(int pack_no);void send_packet(void);void recv_packet(void);int unpack(char *buf,int len);void tv_sub(struct timeval *out,struct timeval *in);void statistics(int signo){ printf("\n--------------------PING statistics-------------------\n"); /* * 总共发送nsend个icmp包，总共接收到返回的nreceived个包， * icmp包的丢失率(nsend-nreceived)/nsend */ printf("%d packets transmitted, %d received , %%%d lost\n", nsend, nreceived, (nsend-nreceived)/nsend*100); close(sockfd); exit(1);}/* 计算校验和的算法 */unsigned short cal_chksum(unsigned short *addr,int len){ int sum=0; int nleft = len; unsigned short *w = addr; unsigned short answer = 0; /* 把ICMP报头二进制数据以2字节为单位累加起来 */ while(nleft > 1){ sum += *w++; nleft -= 2; } /* * 若ICMP报头为奇数个字节，会剩下最后一字节。 * 把最后一个字节视为一个2字节数据的高字节， * 这2字节数据的低字节为0，继续累加 */ if(nleft == 1){ *(unsigned char *)(&answer) = *(unsigned char *)w; sum += answer; /* 这里将 answer 转换成 int 整数 */ } sum = (sum >> 16) + (sum & 0xffff); /* 高位低位相加 */ sum += (sum >> 16); /* 上一步溢出时，将溢出位也加到sum中 */ answer = ~sum; /* 注意类型转换，现在的校验和为16位 */ return answer;}/* 设置ICMP报头，以及将发送的时间设置为ICMP的末尾的数据部分和校验和 */int pack(int pack_no){ int packsize; struct icmp *icmp; struct timeval *tval; icmp = (struct icmp*)sendpacket; icmp->icmp_type = ICMP_ECHO; /* icmp的类型 */ icmp->icmp_code = 0; /* icmp的编码 */ icmp->icmp_cksum = 0; /* icmp的校验和 */ icmp->icmp_seq = pack_no; /* icmp的顺序号 */ icmp->icmp_id = pid; /* icmp的标志符 */ packsize = 8 + datalen; /* icmp8字节的头 加上数据的长度(datalen=56), packsize = 64 */ tval = (struct timeval *)icmp->icmp_data; /* 获得icmp结构中最后的数据部分的指针 */ gettimeofday(tval, NULL); /* 将发送的时间填入icmp结构中最后的数据部分 */ icmp->icmp_cksum = cal_chksum((unsigned short *)icmp, packsize);/*填充发送方的校验和*/ return packsize;}/* 发送三个ICMP报文 */void send_packet(){ int packetsize; /* 每一次发送3个icmp包 */ while(nsend < MAX_NO_PACKETS){ // #define MAX_NO_PACKETS 3 nsend++; packetsize = pack(nsend); /* 设置ICMP报头 */ if(sendto(sockfd, sendpacket, packetsize, 0, (struct sockaddr *)&dest_addr, sizeof(dest_addr)) < 0){ perror("sendto error"); continue; } sleep(1); /* 每隔一秒发送一个ICMP报文 */ }}/* 接收所有ICMP报文 */void recv_packet(){ int n, fromlen; extern int errno; signal(SIGALRM,statistics); fromlen = sizeof(from); /* icmp包源地址的大小*/ while(nreceived < nsend){ alarm(MAX_WAIT_TIME); if((n = recvfrom(sockfd, recvpacket, sizeof(recvpacket), 0, (struct sockaddr *)&from, (socklen_t *)&fromlen)) < 0) { if(errno == EINTR) continue; perror("recvfrom error"); continue; } gettimeofday(&tvrecv, NULL); /* 记录接收到icmp包时的时间 */ if(unpack(recvpacket, n) == -1) continue; nreceived++; }}/* 对ICMP报头解包 */int unpack(char *buf, int len){ int iphdrlen; struct ip *ip; struct icmp *icmp; struct timeval *tvsend; double rtt; ip = (struct ip *)buf; iphdrlen = ip->ip_hl << 2; /* 求ip报头长度,即ip报头的长度标志乘4 */ icmp = (struct icmp *)(buf + iphdrlen); /* 越过ip报头,指向ICMP报头 */ len -= iphdrlen; /* ICMP报头及ICMP数据报的总长度 */ if(len < 8){ /* 小于ICMP报头长度则不合理 */ printf("ICMP packets\'s length is less than 8\n"); return -1; } /* 确保所接收的是我所发的的ICMP的回应 */ if((icmp->icmp_type == ICMP_ECHOREPLY) && (icmp->icmp_id == pid)){ tvsend = (struct timeval *)icmp->icmp_data; tv_sub(&tvrecv, tvsend); /* 接收和发送的时间差 */ /* 以毫秒为单位计算发送和接收的时间差rtt */ rtt = tvrecv.tv_sec * 1000 + tvrecv.tv_usec / 1000; /* 显示相关信息 */ printf("%d byte from %s: icmp_seq=%u ttl=%d time=%.3f ms\n", len, /* ICMP报头及ICMP数据报的总长度 */ inet_ntoa(from.sin_addr), /* ICMP的源地址 */ icmp->icmp_seq, /* icmp包发送的顺序 */ ip->ip_ttl, /* icmp存活的时间 */ rtt); /* 以毫秒为单位计算发送和接收的时间差rtt */ return 0; } else return -1;}int main(int argc,char *argv[]){ struct hostent *host; struct protoent *protocol; unsigned long inaddr = 0l; int size = 50*1024; //50k if(argc < 2){ printf("usage:%s hostname/IP address\n",argv[0]); exit(1); } if((protocol = getprotobyname("icmp")) == NULL){ perror("getprotobyname"); exit(1); } /* 生成使用ICMP的原始套接字,这种套接字只有root才能生成 */ if((sockfd = socket(AF_INET, SOCK_RAW, protocol->p_proto)) < 0){ perror("socket error"); exit(1); } setuid(getuid()); /* 回收root权限,设置当前用户权限 */ /* * 扩大套接字接收缓冲区到50K这样做主要为了减小接收缓冲区溢出的 * 的可能性,若无意中ping一个广播地址或多播地址,将会引来大量应答 */ setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &size, sizeof(size) ); bzero(&dest_addr, sizeof(dest_addr)); dest_addr.sin_family = AF_INET; /* 判断argv[1]是主机名还是ip地址 */ if((inaddr=inet_addr(argv[1])) == INADDR_NONE){ if((host = gethostbyname(argv[1])) == NULL){ /* 是主机名 */ perror("gethostbyname error"); exit(1); } memcpy((char*)&dest_addr.sin_addr, host->h_addr, host->h_length); }else { /* 是ip地址 */ memcpy((char*)&dest_addr.sin_addr, (char*)&inaddr, sizeof(inaddr)); } pid = getpid(); /*获取main的进程id,用于设置ICMP的标志符*/ printf("PING %s(%s): %d bytes data in ICMP packets.\n", argv[1], inet_ntoa(dest_addr.sin_addr), datalen); send_packet(); /* 发送所有ICMP报文 */ recv_packet(); /* 接收所有ICMP报文 */ statistics(SIGALRM); /* 进行统计 */ return 0;}/* 两个timeval结构相减 */void tv_sub(struct timeval *recv, struct timeval *send){ if((recv->tv_usec -= send->tv_usec) < 0){ --recv->tv_sec; recv->tv_usec += 1000000; } recv->tv_sec -= send->tv_sec;}
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