用C写的一个ping工具源程序

 

/************************************************************
******c program of ping ************************************
******Author: Wayne Wang ***********************************
******Website: **************************
******Version:V1.0 *****************************************
******Modified:Feb 17 2011 *********************************
************************************************************/


#include <string.h>
#include <stdlib.h>
#include <stdio.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>
#include <sys/time.h>

#define bool int
#define PACKET_SIZE 4096
#define MAX_WAIT_TIME 3
#define MAX_NO_PACKETS 3
#define _DEBUG_ 0

char sendpacket[PACKET_SIZE];
char recvpacket[PACKET_SIZE];
int sockfd, datalen = 8;
int nsend = 0, nreceived = 0;
struct sockaddr_in dest_addr;
pid_t pid;
struct sockaddr_in from;
struct timeval tvrecv;
int recvflag = 1;

void statistics(int signo);
void requesttimeout(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);
int pingcount = 0, pinginterval = 0, timeout = 0 ;
void tv_sub(struct timeval *out,struct timeval *in);

void requesttimeout(int signo)
{
    recvflag = 0;
    alarm(0);
    printf("Request time out\n");
    return ;
}

void statistics(int signo)
{
    float lostrate = (float)(nsend - nreceived) / nsend*100;
    printf("\n--------------------PING statistics-------------------\n");
    //printf("%d packets transmitted, %d received , %%%f lost\n", nsend, nreceived, (nsend-nreceived)/nsend*100);

    printf(" packets transmitted: %d, received: %d , lost: %d (%.2f%%)\n", nsend, nreceived,(nsend - nreceived), lostrate);
    close(sockfd);
    exit(1);
}

/*校验和算法*/

unsigned short cal_chksum(unsigned short *addr,int len)
{
    int nleft = len;
    int sum = 0;
    unsigned short *w = addr;
    unsigned short 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字节数据的低字节?*/ if (nleft == 1)
    {
        //*(unsigned char *)(&answer)=*(unsigned char *)w;

        //answer = (*(unsigned char *)w) << 8;

        //printf("answer = %x\n", answer);

        sum += *(unsigned char *)w;
        printf("sum = %x\n", sum);
    }
    sum = (sum>>16) + (sum&0xffff);
    sum += (sum>>16);
    answer =~ sum;
    return answer;
}

/*设置ICMP报头*/

int pack(int pack_no)
{
    int packsize;
    struct icmp *icmp;
    struct timeval *tval;
    icmp = (struct icmp*)sendpacket;
    icmp->icmp_type = ICMP_ECHO;
    icmp->icmp_code = 0;
    icmp->icmp_cksum = 0;
    icmp->icmp_seq = pack_no;
    icmp->icmp_id = pid;
    packsize = 8 + datalen;
    tval = (struct timeval *)icmp->icmp_data;
    gettimeofday(tval, NULL); /*记录发送时间*/
    #if _DEBUG_
    printf("sec = %ld, usec = %ld\n", tval->tv_sec, tval->tv_usec);
    #endif
    icmp->icmp_cksum = cal_chksum( (unsigned short *)icmp,packsize); /*校验算法*/
    #if _DEBUG_
    printf("cksum = 0x%x\n", icmp->icmp_cksum);
    #endif
    return packsize;
}

/*发送三个ICMP报文*/

void send_packet()
{
    int packetsize;
    {
        nsend++;
        packetsize = pack(nsend); /*设置ICMP报头*/
        #if _DEBUG_
            printf("nsend = %d, packetsize = %d\n", nsend, packetsize);
        #endif
        if (sendto(sockfd, sendpacket, packetsize, 0,
                (struct sockaddr *)&dest_addr, sizeof(dest_addr)) < 0)
        {
            perror("sendto error");
            return;
        }
        //usleep(1000); /*每隔一秒发送一个ICMP报文*/

    }
}

/*接收所有ICMP报文*/

void recv_packet()
{
    int n, count = 0;
    socklen_t fromlen;
    extern int errno;
    recvflag = 1;
    fd_set rfds;
    struct timeval tv;
    struct timeval starttv;
    struct timeval nowtv;
    double betime;
    int retval = 0, unpack_status = 0;
    gettimeofday(&starttv, NULL);
    tv.tv_sec = timeout;
    tv.tv_usec = 0;
    while (recvflag == 1)
    {
        fromlen = sizeof(from);
        FD_ZERO(&rfds);
        FD_SET(sockfd, &rfds);
        retval = select((sockfd + 1),&rfds, NULL,NULL,&tv);
        if(retval)
        {
            if ((n = recvfrom(sockfd, recvpacket, sizeof(recvpacket),MSG_DONTWAIT,
                (struct sockaddr *)&from, &fromlen)) < 0)
            {
                if (errno == EINTR)
                {
                    printf("errno == EINTR\n");
                }
                #if _DEBUG_
                    printf("n is:%d\n",n);
                #endif
                return ;
            }
        unpack_status = unpack(recvpacket, n);
        if(unpack_status == 1)
        {
            nreceived++;
            return ;
        }
        else if(unpack_status == -3)
        {
            return ;
        }
        else if(unpack_status == -2)
        {
            gettimeofday(&nowtv, NULL);
            tv_sub(&nowtv, &starttv);
            betime = (nowtv.tv_sec*1000 + (double)nowtv.tv_usec/1000)/1000;
            if(betime >= timeout)
            {
                printf("Request time out \n");
                return;
            }
            else
            {
                //tv_sub(&tv, nowtv);

                continue;
            }
        }
        else
        {
            printf("Protocol data error\n");
            recvflag = 0;
            return;
        }
     }
     else
     {
         printf("Request time out \n");
         return ;
     }
    }
    return;
}

/*剥去ICMP报头*/

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; /* ip_hl is the words of ip header*/
    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*/
    //printf("%d, icmp_id = %d\n", ICMP_ECHOREPLY, icmp->icmp_id);

    if ((icmp->icmp_type == ICMP_ECHOREPLY) && (icmp->icmp_id == pid))
    {
        gettimeofday(&tvrecv, NULL);
        #if _DEBUG_
            printf("sec = %ld, usec = %ld\n", tvrecv.tv_sec, tvrecv.tv_usec);
        #endif
        tvsend = (struct timeval *)icmp->icmp_data;
        tv_sub(&tvrecv, tvsend); /*接收和发送的时间差*/
        rtt = tvrecv.tv_sec*1000 + (double)tvrecv.tv_usec/1000; /*以毫秒为单位计算rtt*/
        /*显示相关信息*/
        printf("%d byte from %s: icmp_seq=%u ttl=%d rtt=%.3f ms\n",
        len, inet_ntoa(from.sin_addr), icmp->icmp_seq, ip->ip_ttl, rtt);
        return 1;
    }
    else if( icmp->icmp_type == 3)
    {
     printf("From:%s Destination host unreachable \n",inet_ntoa(from.sin_addr));
        return -3;
    }
    else if (icmp->icmp_id != pid )
    {
        return -2;
    }
    else
    {
        return -1;
    }
}

int main(int argc,char *argv[])
{
    struct hostent *host;
    struct protoent *protocol;
    unsigned long inaddr = 0l;
    int i;
    char *desthost;
    bool runflag=1;
    memset(sendpacket, 'a', sizeof(sendpacket)); // set sendpacket's content to "aaaaaaa"

    int size = 50*1024;
    if (argc < 2)
    {
        printf("usage:%s [-c count] [-i interval] [-t time of timeout] [-h show help message] destination(hostname/IP address)\n",argv[0]);
        exit(1);
    }
    desthost=argv[argc-1];
    for(i=1; i<argc; i++)
    {
        if( !strcmp(argv[i], "-c")){
             pingcount = atoi(argv[(i+1)]);
            // printf("cccccc:%d\n",pcount);

        }
        if( !strcmp(argv[i], "-i")) pinginterval = atoi(argv[(i+1)]);
        if( !strcmp(argv[i], "-t")) timeout = atoi(argv[(i+1)]);
        if( !strcmp(argv[i], "-h"))
        {
             printf("This is a ping tool\n");
             printf("usage:%s [-c count] [-i interval] [-t time of timeout] [-h show help message] destination(hostname/IP address)\n",argv[0]);
             exit(1);
        }
    }
    //pcount,pinterval,ptimeout

    if(pinginterval == 0) pinginterval = 1;
    if(timeout == 0) timeout = MAX_WAIT_TIME;
    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 _DEBUG_
        printf("the protocol number used is %d\n", protocol->p_proto);
    #endif
    if ((sockfd = socket(AF_INET, SOCK_RAW, protocol->p_proto)) < 0)
    {
        perror("socket error");
        exit(1);
    }
    /* 回收root权限,设置当前用户权限*/
    //setuid(getuid());

    /*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;
    /*判断是主机名还是ip地址*/
    //if ((inaddr = inet_addr(argv[1])) == INADDR_NONE)

    if ((inaddr = inet_addr(desthost)) == INADDR_NONE)
    {
        if ((host = gethostbyname(desthost)) == 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.s_addr, (char *)&inaddr, sizeof(inaddr));
    }

    /*获取main的进程id,用于设置ICMP的标志符*/
    pid = getpid();
    //printf("main pid:%d\n",pid);

    printf("PING %s(%s): %d bytes data in ICMP packets.\n",desthost,
        inet_ntoa(dest_addr.sin_addr),datalen);
    // signal(SIGALRM, requesttimeout);

    signal(SIGINT, statistics);
    //while (nsend < MAX_NO_PACKETS)

    while (runflag)
    {
        send_packet(); /*发送所有ICMP报文*/
    //    printf("aaaaaaaaaa\n");

        recv_packet(); /*接收所有ICMP报文*/
        sleep(pinginterval);
        if((pingcount != 0) && (nsend >= pingcount)) runflag = 0;
    }
    statistics(SIGALRM); /*进行统计*/
    return 0;
}

/*两个timeval结构相减*/

void tv_sub(struct timeval *out, struct timeval *in)
{
  if ((out->tv_usec -= in->tv_usec) < 0)
  {
    --out->tv_sec;
    out->tv_usec += 1000000;
  }
  out->tv_sec -= in->tv_sec;
}