C代码实现Linux下模拟ping命令

概述C代码实现Linux下模拟ping命令

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/******************************************************** *  IP报头格式数据结构定义在<netinet/ip.h>中    * *  ICMP数据结构定义在<netinet/ip_icmp.h>中     * *  套接字地址数据结构定义在<netinet/in.h>中 * ********************************************************/#include <stdio.h>#include <stdlib.h>#include <signal.h>#include <arpa/inet.h>#include <sys/types.h>#include <sys/socket.h>#include <unistd.h>#include <netinet/in.h>#include <netinet/ip.h>#include <netinet/ip_icmp.h>#include <netdb.h>#include <setjmp.h>#include <errno.h>#define PACKET_SIZE 4096#define MAX_WAIT_TIME   5#define MAX_NO_PACKETS  10000char *addr[];char sendpacket[PACKET_SIZE];char recvpacket[PACKET_SIZE];int sockfd,datalen = 56;int nsend = 0,nreceived = 0;double temp_rtt[MAX_NO_PACKETS];double all_time = 0;double min = 0;double max = 0;double avg = 0;double mdev = 0;struct sockaddr_in dest_addr;struct sockaddr_in from;struct timeval tvrecv;pID_t pID;voID statistics(int sig);voID send_packet(voID);voID recv_packet(voID);voID computer_rtt(voID);voID tv_sub(struct timeval *out,struct timeval *in);int pack(int pack_no);int unpack(char *buf,int len);unsigned short cal_checksum(unsigned short *addr,int len);/*计算rtt最小、大值，平均值，算术平均数差*/voID computer_rtt(){    double sum_avg = 0;    int i;    min = max = temp_rtt[0];    avg = all_time/nreceived;    for(i=0; i<nreceived; i++){        if(temp_rtt[i] < min)            min = temp_rtt[i];        else if(temp_rtt[i] > max)            max = temp_rtt[i];        if((temp_rtt[i]-avg) < 0)            sum_avg += avg - temp_rtt[i];        else            sum_avg += temp_rtt[i] - avg;         }    mdev = sum_avg/nreceived;}/****统计数据函数****/voID statistics(int sig){    computer_rtt();     //计算rtt    printf("\n------ %s Ping statistics ------\n",addr[0]);    printf("%d packets transmitted,%d received,%d%% packet loss,time %.f ms\n",nsend,nreceived,(nsend-nreceived)/nsend*100,all_time);    printf("rtt min/avg/max/mdev = %.3f/%.3f/%.3f/%.3f ms\n",min,avg,max,mdev);    close(sockfd);    exit(1);}/****检验和算法****/unsigned short cal_chksum(unsigned short *addr,int len){    int nleft = len;    int sum = 0;    unsigned short *w = addr;    unsigned short check_sum = 0;    while(nleft>1)      //ICMP包头以字（2字节）为单位累加    {        sum += *w++;        nleft -= 2;    }    if(nleft == 1)      //ICMP为奇数字节时，转换最后一个字节，继续累加    {        *(unsigned char *)(&check_sum) = *(unsigned char *)w;        sum += check_sum;    }    sum = (sum >> 16) + (sum & 0xFFFF);    sum += (sum >> 16);    check_sum = ~sum;   //取反得到校验和    return check_sum;}/*设置ICMP报头*/int pack(int pack_no){    int i,packsize;    struct icmp *icmp;    struct timeval *tval;    icmp = (struct icmP*)sendpacket;    icmp->icmp_type = ICMP_ECHO;    //ICMP_ECHO类型的类型号为0    icmp->icmp_code = 0;    icmp->icmp_cksum = 0;    icmp->icmp_seq = pack_no;   //发送的数据报编号    icmp->icmp_ID = pID;    packsize = 8 + datalen;     //数据报大小为64字节    tval = (struct timeval *)icmp->icmp_data;    gettimeofday(tval,NulL);        //记录发送时间    //校验算法    icmp->icmp_cksum =  cal_chksum((unsigned short *)icmp,packsize);        return packsize;}/****发送三个ICMP报文****/voID send_packet(){    int packetsize;    if(nsend < MAX_NO_PACKETS)    {        nsend++;        packetsize = pack(nsend);   //设置ICMP报头        //发送数据报        if(sendto(sockfd,sendpacket,packetsize,(struct sockaddr *)&dest_addr,sizeof(dest_addr)) < 0)        {            perror("sendto error");        }    }}/****接受所有ICMP报文****/voID recv_packet(){    int n,fromlen;    extern int error;    fromlen = sizeof(from);    if(nreceived < nsend)    {           //接收数据报        if((n = recvfrom(sockfd,recvpacket,sizeof(recvpacket),(struct sockaddr *)&from,&fromlen)) < 0)        {            perror("recvfrom error");        }        gettimeofday(&tvrecv,NulL);     //记录接收时间        unpack(recvpacket,n);       //剥去ICMP报头        nreceived++;    }}/******剥去ICMP报头******/int unpack(char *buf,int len){    int i;    int iphdrlen;       //ip头长度    struct ip *ip;    struct icmp *icmp;    struct timeval *tvsend;    double rtt;    ip = (struct ip *)buf;    iphdrlen = ip->ip_hl << 2;  //求IP报文头长度，即IP报头长度乘4    icmp = (struct icmp *)(buf + iphdrlen); //越过IP头，指向ICMP报头    len -= iphdrlen;    //ICMP报头及数据报的总长度    if(len < 8)     //小于ICMP报头的长度则不合理    {        printf("ICMP packet\'s length is less than 8\n");        return -1;    }    //确保所接收的是所发的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rtt        rtt = tvrecv.tv_sec*1000 + tvrecv.tv_usec/1000;        temp_rtt[nreceived] = rtt;        all_time += rtt;    //总时间        //显示相关的信息        printf("%d bytes from %s: icmp_seq=%u ttl=%d time=%.1f ms\n",len,inet_ntoa(from.sin_addr),icmp->icmp_seq,ip->ip_ttl,rtt);    }    else return -1;}//两个timeval相减voID tv_sub(struct timeval *recvtime,struct timeval *sendtime){    long sec = recvtime->tv_sec - sendtime->tv_sec;    long usec = recvtime->tv_usec - sendtime->tv_usec;    if(usec >= 0){        recvtime->tv_sec = sec;        recvtime->tv_usec = usec;    }else{        recvtime->tv_sec = sec - 1;        recvtime->tv_usec = -usec;    }}/*主函数*/main(int argc,char *argv[]){    struct hostent *host;    struct protoent *protocol;    unsigned long inaddr = 0;//  int waittime = MAX_WAIT_TIME;    int size = 50 * 1024;    addr[0] = argv[1];    //参数小于两个    if(argc < 2)            {        printf("usage:%s hostname/IP address\n",argv[0]);        exit(1);    }    //不是ICMP协议    if((protocol = getprotobyname("icmp")) == NulL)    {        perror("getprotobyname");        exit(1);    }    //生成使用ICMP的原始套接字，只有root才能生成    if((sockfd = socket(AF_INET,SOCK_RAW,protocol->p_proto)) < 0)    {        perror("socket error");        exit(1);    }    //回收root权限，设置当前权限    setuID(getuID());    /*扩大套接字的接收缓存区导50K，这样做是为了减小接收缓存区溢出的      可能性，若无意中Ping一个广播地址或多播地址，将会引来大量的应答*/    setsockopt(sockfd,Sol_SOCKET,SO_RCVBUF,&size,sizeof(size));    bzero(&dest_addr,sizeof(dest_addr));    //初始化    dest_addr.sin_family = AF_INET;     //套接字域是AF_INET(网络套接字)    //判断主机名是否是IP地址    if(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        dest_addr.sin_addr.s_addr = inet_addr(argv[1]);    }    pID = getpID();    printf("Ping %s(%s):%d bytes of data.\n",argv[1],inet_ntoa(dest_addr.sin_addr),datalen);    //当按下ctrl+c时发出中断信号，并开始执行统计函数    signal(SIGINT,statistics);      while(nsend < MAX_NO_PACKETS){        sleep(1);       //每隔一秒发送一个ICMP报文        send_packet();      //发送ICMP报文        recv_packet();      //接收ICMP报文    }    return 0;}

/******************************************************** *  IP报头格式数据结构定义在<netinet/ip.h>中    * *  ICMP数据结构定义在<netinet/ip_icmp.h>中     * *  套接字地址数据结构定义在<netinet/in.h>中 * ********************************************************/#include <stdio.h>#include <stdlib.h>#include <signal.h>#include <arpa/inet.h>#include <sys/types.h>#include <sys/socket.h>#include <unistd.h>#include <netinet/in.h>#include <netinet/ip.h>#include <netinet/ip_icmp.h>#include <netdb.h>#include <setjmp.h>#include <errno.h>#define PACKET_SIZE 4096#define MAX_WAIT_TIME   5#define MAX_NO_PACKETS  10000char *addr[];char sendpacket[PACKET_SIZE];char recvpacket[PACKET_SIZE];int sockfd,statistics);      while(nsend < MAX_NO_PACKETS){        sleep(1);       //每隔一秒发送一个ICMP报文        send_packet();      //发送ICMP报文        recv_packet();      //接收ICMP报文    }    return 0;}

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