Ping代码

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

#define MAX_PINGCOUNT    3

#define u8    u_int8_t
#define u16 u_int16_t
#define u32    u_int32_t

#define ROTATE(x,b) (((x) << (b)) | ((x) >> (32 - (b))))
#define MUSH(i,b) x = t[i] += (((x ^ seed[i]) + sum) ^ ROTATE(x,b));

//#define DEBUG 1
#ifdef DEBUG
#define DEBUGP(format,args...) fprintf(stdout, format, ##args)
#else
#define DEBUGP(format,args...)
#endif

static u32 seed[32];
static u32 in[12];
static u32 out[8];

static int difftimeval(struct timeval *end, struct timeval *start)
{
    unsigned int timeuse;

    return 1000000 * ( end->tv_sec - start->tv_sec ) + end->tv_usec - start->tv_usec;
}

static int retry_send(void)
{
    struct timespec waiter;
    if (errno == EAGAIN) {
        waiter.tv_sec = 0;
        waiter.tv_nsec = 10000;
        nanosleep(&waiter, NULL);
        return 1;
    }

    if (errno == EINTR)
        return 1;

    return 0;
}

static void surf(void)
{
    u32 t[12];
    u32 x;
    u32 sum = 0;
    int r;
    int i;
    int loop;

    for (i = 0; i < 12; ++i) t[i] = in[i] ^ seed[12 + i];
    for (i = 0; i < 8; ++i) out[i] = seed[24 + i];
    x = t[11];
    for (loop = 0; loop < 2; ++loop) {
        for (r = 0; r < 16; ++r) {
            sum += 0x9e3779b9;
            MUSH(0,5) MUSH(1,7) MUSH(2,9) MUSH(3,13)
            MUSH(4,5) MUSH(5,7) MUSH(6,9) MUSH(7,13)
            MUSH(8,5) MUSH(9,7) MUSH(10,9) MUSH(11,13)
        }
        for (i = 0; i < 8; ++i) out[i] ^= t[i + 4];
    }
}

unsigned short rand16(void)
{
    static int outleft = 0;

    if (!outleft) {
        if (!++in[0]) if (!++in[1]) if (!++in[2]) ++in[3];
        surf();
        outleft = 8;
    }

    return (unsigned short) out[--outleft];
}

static int fix_fd(int fd)
{
    int flags;

    if ((flags = fcntl(fd, F_GETFL)) == -1 ||
     fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
        return 0;

    return 1;
}

static int open_socket(void)
{
    int fd;
    int zeroopt = 0;

    if ((fd = socket (AF_INET, SOCK_RAW, IPPROTO_ICMP)) != -1) {
        if (!fix_fd(fd) ||
         setsockopt(fd, SOL_SOCKET, SO_DONTROUTE, &zeroopt, sizeof(zeroopt)) == -1) {
            close(fd);
            fd = -1;
        }
    }

    return fd;
}

static int icmp_ping(int fd, struct in_addr addr, int timeout)
{
    /* Try and get an ICMP echo from a machine. */

    /* Note that whilst in the three second wait, we check for
     (and service) events on the DNS and TFTP sockets, (so doing that
     better not use any resources our caller has in use...)
     but we remain deaf to signals or further DHCP packets. */

    struct sockaddr_in saddr;
    struct {
        struct ip ip;
        struct icmp icmp;
    } packet;
    unsigned short id = rand16();
    unsigned int i, j;
    int gotreply = 0;
    struct timeval start, now;

    saddr.sin_family = AF_INET;
    saddr.sin_port = 0;
    saddr.sin_addr = addr;
#ifdef HAVE_SOCKADDR_SA_LEN
    saddr.sin_len = sizeof(struct sockaddr_in);
#endif

    memset(&packet.icmp, 0, sizeof(packet.icmp));
    packet.icmp.icmp_type = ICMP_ECHO;
    packet.icmp.icmp_id = id;
    for (j = 0, i = 0; i < sizeof(struct icmp) / 2; i++)
        j += ((u16 *)&packet.icmp)[i];
    while (j>>16)
        j = (j & 0xffff) + (j >> 16);
    packet.icmp.icmp_cksum = (j == 0xffff) ? j : ~j;

    while (sendto(fd, (char *)&packet.icmp, sizeof(struct icmp), 0,
     (struct sockaddr *)&saddr, sizeof(saddr)) == -1 &&
     retry_send());

    gettimeofday(&start, NULL);
    now = start;
    do {
        struct timeval tv;
        fd_set rset, wset;
        struct sockaddr_in faddr;
        int maxfd = fd;
        socklen_t len = sizeof(faddr);

        tv.tv_usec = 200000;
        tv.tv_sec = 0;

        FD_ZERO(&rset);
        FD_ZERO(&wset);
        FD_SET(fd, &rset);
        //set_dns_listeners(now, &rset, &maxfd);
        //set_log_writer(&wset, &maxfd);

        if (select(maxfd+1, &rset, &wset, NULL, &tv) < 0) {
            FD_ZERO(&rset);
            FD_ZERO(&wset);
        }

        gettimeofday(&now, NULL);

        //check_log_writer(&wset);
        //check_dns_listeners(&rset, now);

        if (FD_ISSET(fd, &rset) &&
         recvfrom(fd, &packet, sizeof(packet), 0,
         (struct sockaddr *)&faddr, &len) == sizeof(packet) &&
         saddr.sin_addr.s_addr == faddr.sin_addr.s_addr &&
         packet.icmp.icmp_type == ICMP_ECHOREPLY &&
         packet.icmp.icmp_seq == 0 &&
         packet.icmp.icmp_id == id) {
            gotreply = 1;
            break;
        }
    }while(difftimeval(&now, &start) < timeout);
    DEBUGP("gotreply = %d\n", gotreply);
    return gotreply;
}

int ping(const char *daddr, int pingcount)
{
    struct in_addr addr;
    unsigned int timeout = 2 * 1000;
    int gotreply = 0;
    int fd, i;

    if ((fd = open_socket()) == -1)
        return -1;

    addr.s_addr = inet_addr(daddr);
    if(addr.s_addr == INADDR_NONE){
        close(fd);
        return -3;
    }

    for(i = 0; i < pingcount; i++){
        gotreply = icmp_ping(fd, addr, timeout * 1000);
        if(gotreply) break;
    }

    close(fd);
    if(gotreply <= 0) return -4;

    return 0;
}

main(int argc, char **argv)
{
    if (argc < 2){
        fprintf(stdout, "Please Enter IP\n");
        return 1;
    }
    int reply;
    reply = ping(argv[1], MAX_PINGCOUNT);
    if (reply == 0){
        fprintf(stdout, "Connect\n");
        return  0;
    }else{
        fprintf(stdout, "Disconect\n");
        return  2;
    }
}