计算机网络ping的C语言代码

以下是计算机网络中ping的C语言代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <errno.h>

#define PACKET_SIZE     4096
#define TIMEOUT         4
#define MAX_NO_PACKETS  3

unsigned short checksum(void *b, int len)
{       
    unsigned short *buf = b; 
    unsigned int sum=0; 
    unsigned short result; 

    for ( sum = 0; len > 1; len -= 2 ) 
        sum += *buf++ ; 
    if ( len == 1 ) 
        sum += *(unsigned char*)buf; 
    sum = (sum >> 16) + (sum & 0xFFFF); 
    sum += (sum >> 16); 
    result = ~sum; 
    return result;
}

int pack(int pack_no, char *sendpacket)
{   
    int i, 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 = getpid(); 
    packsize = 8 + 56; 
    tval = (struct timeval*)icmp->icmp_data; 
    gettimeofday(tval, NULL); 
    icmp->icmp_cksum = checksum(sendpacket, packsize); 
    return packsize;
}

int unpack(char *buf, int len, char *addr)
{
    int i, iphdrlen, rtt; 
    struct ip *ip; 
    struct icmp *icmp; 
    struct timeval *tvsend, tvrecv, tvresult;

    ip = (struct ip*)buf; 
    iphdrlen = ip->ip_hl << 2;
    icmp = (struct icmp*)(buf + iphdrlen);
    len -= iphdrlen;

    if ( len < 8 ) 
    {   
        printf("ICMP packets\'s length is less than 8\n"); 
        return -1;
    }   

    if ( (icmp->icmp_type == ICMP_ECHOREPLY) && (icmp->icmp_id == getpid()))
    {   
        tvsend = (struct timeval*)icmp->icmp_data; 
        gettimeofday(&tvrecv, NULL); 
        tvresult = tvsub(tvrecv, *tvsend); 
        rtt = tvresult.tv_sec * 1000 + tvresult.tv_usec / 1000; 
        printf("%d byte from %s: icmp_seq=%u ttl=%d rtt=%d ms\n", len, addr, icmp->icmp_seq, ip->ip_ttl, rtt); 
        return 0;
    }
    else 
        return -1;
}

struct timeval tvsub(struct timeval timeval1, struct timeval timeval2)
{       
    struct timeval result; 
    result.tv_sec = timeval1.tv_sec - timeval2.tv_sec; 
    result.tv_usec = timeval1.tv_usec - timeval2.tv_usec; 
    if (result.tv_usec < 0) 
    {       
        --result.tv_sec; 
        result.tv_usec += 1000000;
    }   

    return result;
}

int Ping(char *ipaddress)
{       
    struct hostent *host; 
    struct icmp sendicmp; 
    struct sockaddr_in from; 
    struct sockaddr_in to; 
    int from_len = 0; 
    int sockfd = 0, nsend = 0, nreceived = 0, i = 0, packet_no = 0; 
    char sendpacket[PACKET_SIZE] = {0}; 
    char recvbuf[PACKET_SIZE] = {0}; 

    memset(&from, 0, sizeof(from));
    memset(&to, 0, sizeof(to));

    if ((sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0)
    {   
        perror("socket error"); 
        return -1;
    }

    setuid(getuid());
    bzero(&sendicmp, sizeof(sendicmp));
    to.sin_family = AF_INET;
    if ( inet_addr(ipaddress) == INADDR_NONE ) 
    {       
        if ((host = gethostbyname(ipaddress)) == NULL) 
        {   
            perror("gethostbyname error"); 
            return -1;
        }   
        memcpy(&to.sin_addr, host->h_addr, host->h_length);
    }
    else 
        to.sin_addr.s_addr = inet_addr(ipaddress);

    printf("Ping %s ...\n", ipaddress); 

    for ( i = 0; i < MAX_NO_PACKETS; i++) 
    {   
        nsend = pack(packet_no++, sendpacket); 
        if ( sendto(sockfd, sendpacket, nsend, 0, (struct sockaddr*)&to, sizeof(to)) < 0 ) 
        {   
            perror("sendto error"); 
            continue;
        }   
        nreceived++; 

        if ( recvfrom(sockfd, recvbuf, sizeof(recvbuf), 0, (struct sockaddr*)&from, &from_len) < 0 ) 
        {   
            perror("recvform error"); 
            continue;
        }   

        if ( unpack(recvbuf, sizeof(recvbuf), inet_ntoa(from.sin_addr)) == -1 ) 
            continue;
        sleep(1);
    }

    printf("Ping statistics for %s:\n", ipaddress); 
    printf("\tPackets: Sent = %d, Received = %d, Lost = %d(%d%% lost)\n", packet_no, nreceived, (packet_no - nreceived), ((packet_no - nreceived) * 100) / packet_no); 
    close(sockfd); 
    return 0;
}

int main(int argc, char *argv[])
{
    if ( argc < 2 ) 
    {   
        printf("Usage: %s IP\n", argv[0]); 
        return -1;
    }   

    Ping(argv[1]); 

    return 0;
}

注意：此代码需要在 Linux 或 Mac 上编译运行，Windows 上需要进行一些修改才能编译运行。