C++实现简单的ping功能

一代码

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

#define MAX_SIZE 1024

char send_buf[MAX_SIZE];
char recv_buf[MAX_SIZE];
int nsend = 0, nrecv = 0;
int datalen = 56;

    //统计结果
void statistics(int signum)
{
    printf("\n----------------PING statistics---------------\n");
    printf("%d packets transmitted,%d recevid,%%%d lost\n", nsend, nrecv, (nsend - nrecv) / nsend * 100);
    exit(EXIT_SUCCESS);
}

    //校验和算法
int calc_chsum(unsigned short *addr, int len)
{
    int sum = 0, n = len;
    unsigned short answer = 0;
    unsigned short *p = addr;
        
    //每两个字节相加
    while (n > 1)
    {
        sum += *p++;
        n -= 2;
    }
        
    //处理数据大小是奇数，在最后一个字节后面补0
    if (n == 1)
    {
        *((unsigned char *)&answer) = *(unsigned char *)p;
        sum += answer;
    }
        
    //将得到的sum值的高2字节和低2字节相加
    sum = (sum >> 16) + (sum & 0xffff);
        
    //处理溢出的情况
    sum += sum >> 16;
    answer = ~sum;

    return answer;
}

int pack(int pack_num)
{
    int packsize;
    struct icmp *icmp;
    struct timeval *tv;

    icmp = (struct icmp *)send_buf;
    icmp->icmp_type = ICMP_ECHO;
    icmp->icmp_code = 0;
    icmp->icmp_cksum = 0;
    icmp->icmp_id = htons(getpid());
    icmp->icmp_seq = htons(pack_num);
    tv = (struct timeval *)icmp->icmp_data;

            //记录发送时间
    if (gettimeofday(tv, NULL) < 0)
    {
        perror("Fail to gettimeofday");
        return -1;
    }
        
    packsize = 8 + datalen;
    icmp->icmp_cksum = calc_chsum((unsigned short *)icmp, packsize);
        
    return packsize;
}

int send_packet(int sockfd, struct sockaddr *paddr)
{
    int packsize;
        
    //将send_buf填上a
    memset(send_buf, 'a', sizeof(send_buf));

    nsend++;
    //打icmp包
    packsize = pack(nsend);

    if (sendto(sockfd, send_buf, packsize, 0, paddr, sizeof(struct sockaddr)) < 0)
    {
        perror("Fail to sendto");
        return -1;
    }

    return 0;
}

struct timeval time_sub(struct timeval *tv_send, struct timeval *tv_recv)
{
    struct timeval ts;

    if (tv_recv->tv_usec - tv_send->tv_usec < 0)
    {
        tv_recv->tv_sec--;
        tv_recv->tv_usec += 1000000;
    }

    ts.tv_sec = tv_recv->tv_sec - tv_send->tv_sec;
    ts.tv_usec = tv_recv->tv_usec - tv_send->tv_usec;

    return ts;
}

int unpack(int len, struct timeval *tv_recv, struct sockaddr *paddr, char *ipname)
{
    struct ip *ip ;
    struct icmp *icmp ;
    struct timeval *tv_send,
     ts ;
    int ip_head_len ;
    float rtt ;

    ip = (struct ip *)recv_buf ;
    ip_head_len = ip->ip_hl << 2 ;
    icmp = (struct icmp *)(recv_buf + ip_head_len) ;

    len -= ip_head_len ;
    if(len < 8)
    {
        printf("ICMP packets\'s is less than 8.\n") ;
        return - 1 ;
    }
            
    if(ntohs(icmp->icmp_id) == getpid() && icmp->icmp_type == ICMP_ECHOREPLY)
    {
        nrecv++ ;
        tv_send = (struct timeval *)icmp->icmp_data ;
        ts = time_sub(tv_send, tv_recv) ;
        rtt = ts.tv_sec * 1000 + (float)ts.tv_usec / 1000 ;//以毫秒为单位
        printf("%d bytes from %s (%s):icmp_req = %d ttl=%d time=%.3fms.\n",
        len,
        ipname,
        inet_ntoa(((struct sockaddr_in *)paddr)->sin_addr),
        ntohs(icmp->icmp_seq),
        ip->ip_ttl,
        rtt) ;
    }
        
    return 0 ;
}

int recv_packet(int sockfd, char *ipname)
{
    socklen_t addr_len,
     n ;
    struct timeval tv ;
    struct sockaddr from_addr ;
        
    addr_len = sizeof(struct sockaddr) ;
    if((n = recvfrom(sockfd, recv_buf, sizeof(recv_buf), 0,&from_addr, &addr_len)) < 0)
    {
        perror("Fail to recvfrom") ;
        return - 1 ;
    }

    if(gettimeofday(&tv, NULL) < 0)
    {
        perror("Fail to gettimeofday") ;
        return - 1 ;
    }

    unpack(n, &tv, &from_addr, ipname) ;

    return 0 ;
}


int main(int argc, char *argv[])
{
    int size = 50 * 1024 ;
    int sockfd,
    netaddr ;
    struct protoent *protocol ;
    struct hostent *host ;
    struct sockaddr_in peer_addr ;
        
    if(argc < 2)
    {
        fprintf(stderr, "usage : %s ip.\n", argv[0]) ;
        exit(EXIT_FAILURE) ;
    }
        
    //获取icmp的信息
    if((protocol = getprotobyname("icmp")) == NULL)
    {
        perror("Fail to getprotobyname") ;
        exit(EXIT_FAILURE) ;
    }
        
    //创建原始套接字
    if((sockfd = socket(AF_INET, SOCK_RAW, protocol->p_proto)) < 0)
    {
        perror("Fail to socket") ;
        exit(EXIT_FAILURE) ;
    }

    //回收root权限,设置当前用户权限
    setuid(getuid()) ;

    /*
     扩大套接子接收缓冲区到50k，这样做主要为了减少接收缓冲区溢出的可能性
     若无影中ping一个广播地址或多播地址，将会引来大量应答
     */
    if(setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &size, sizeof(size)) < 0)
    {
        perror("Fail to setsockopt") ;
        exit(EXIT_FAILURE) ;
    }

    //填充对方的地址
    bzero(&peer_addr, sizeof(peer_addr)) ;
    peer_addr.sin_family = AF_INET ;
    //判断是主机名(域名)还是ip
    if((netaddr = inet_addr(argv[1])) == INADDR_NONE)
    {    
        //是主机名（域名）
        if((host = gethostbyname(argv[1])) == NULL)
        {
            fprintf(stderr, "%s unknown host : %s.\n", argv[0], argv[1]) ;
            exit(EXIT_FAILURE) ;
        }

        memcpy((char *)&peer_addr.sin_addr, host->h_addr, host->h_length) ;
            
    }
    else
    {//ip地址
        peer_addr.sin_addr.s_addr = netaddr ;
    }
            
    //注册信号处理函数
    signal(SIGALRM, statistics) ;
    signal(SIGINT, statistics) ;
    alarm(5) ;

    //打印开始信息
    printf("PING %s(%s) %d bytes of data.\n", argv[1], inet_ntoa(peer_addr.sin_addr), datalen) ;

    //发送包文和接收报文
    while(1)
    {
        send_packet(sockfd, (struct sockaddr *)&peer_addr) ;
        recv_packet(sockfd, argv[1]) ;
        alarm(5) ;
        sleep(1) ;
    }

    exit(EXIT_SUCCESS) ;    
}

二运行

[root@localhost test]# ./test 192.168.0.121
PING 192.168.0.121(192.168.0.121) 56 bytes of data.
^C
----------------PING statistics---------------
1 packets transmitted,0 recevid,%100 lost
[root@localhost test]# ./test 192.168.0.120
PING 192.168.0.120(192.168.0.120) 56 bytes of data.
64 bytes from 192.168.0.120 (192.168.0.120):icmp_req = 1 ttl=64 time=0.451ms.
64 bytes from 192.168.0.120 (192.168.0.120):icmp_req = 2 ttl=64 time=0.309ms.
64 bytes from 192.168.0.120 (192.168.0.120):icmp_req = 3 ttl=64 time=0.526ms.
64 bytes from 192.168.0.120 (192.168.0.120):icmp_req = 4 ttl=64 time=0.233ms.
64 bytes from 192.168.0.120 (192.168.0.120):icmp_req = 5 ttl=64 time=0.236ms.
64 bytes from 192.168.0.120 (192.168.0.120):icmp_req = 6 ttl=64 time=0.297ms.
64 bytes from 192.168.0.120 (192.168.0.120):icmp_req = 7 ttl=64 time=0.279ms.
64 bytes from 192.168.0.120 (192.168.0.120):icmp_req = 8 ttl=64 time=0.290ms.
64 bytes from 192.168.0.120 (192.168.0.120):icmp_req = 9 ttl=64 time=0.296ms.
64 bytes from 192.168.0.120 (192.168.0.120):icmp_req = 10 ttl=64 time=0.234ms.
64 bytes from 192.168.0.120 (192.168.0.120):icmp_req = 11 ttl=64 time=0.235ms.
64 bytes from 192.168.0.120 (192.168.0.120):icmp_req = 12 ttl=64 time=0.294ms.
^C
----------------PING statistics---------------
12 packets transmitted,12 recevid,%0 lost
[root@localhost test]# ./test www.baidu.com
PING www.baidu.com(220.181.111.37) 56 bytes of data.
64 bytes from www.baidu.com (220.181.111.37):icmp_req = 1 ttl=54 time=28.862ms.
64 bytes from www.baidu.com (220.181.111.37):icmp_req = 1 ttl=54 time=1029.613ms.
64 bytes from www.baidu.com (220.181.111.37):icmp_req = 2 ttl=54 time=1001.167ms.
64 bytes from www.baidu.com (220.181.111.37):icmp_req = 2 ttl=54 time=2001.564ms.
64 bytes from www.baidu.com (220.181.111.37):icmp_req = 3 ttl=54 time=2001.395ms.
64 bytes from www.baidu.com (220.181.111.37):icmp_req = 3 ttl=54 time=3001.786ms.
^C
----------------PING statistics---------------
6 packets transmitted,6 recevid,%0 lost

C++实现简单的ping功能

猜你喜欢