获取linux内核所有ip

获取linux内核所有ip(C语言)

经常遇到获取接口ip。记录一下，方便后续使用。

#include #include #include #include #include #include #include #include typedef unsigned int    sf_uint32_t;typedef unsigned int    in_addr_t;static inline char* print_ip1(sf_uint32_t ip){    unsigned char* ip_tmp = (unsigned char*) &ip;    static char buff[20];    memset(buff ,0 ,sizeof(buff));    snprintf(buff, sizeof(buff), "%d.%d.%d.%d", ip_tmp[0], ip_tmp[1], ip_tmp[2],             ip_tmp[3]);    return buff;}in_addr_tget_myaddr(void){    int             sd, i, lastlen = 0;    struct ifconf   ifc;    struct ifreq   *ifrp = NULL;    in_addr_t       addr;    char           *buf = NULL;    if ((sd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {        return 0;    }    /*     * Cope with lots of interfaces and brokenness of ioctl SIOCGIFCONF on     * some platforms; see W. R. Stevens, ``Unix Network Programming Volume     * I'', p.435.       */    for (i = 8;; i += 8) {        buf = (char *) calloc(i, sizeof(struct ifreq));        if (buf == NULL) {            close(sd);            return 0;        }        ifc.ifc_len = i * sizeof(struct ifreq);        ifc.ifc_buf = (caddr_t) buf;        if (ioctl(sd, SIOCGIFCONF, (char *) &ifc) < 0) {            if (errno != EINVAL || lastlen != 0) {                /*                 * Something has gone genuinely wrong.                   */                free(buf);                close(sd);                return 0;            }            /*             * Otherwise, it could just be that the buffer is too small.               */        } else {            if (ifc.ifc_len == lastlen) {                /*                 * The length is the same as the last time; we're done.                   */                break;            }            lastlen = ifc.ifc_len;        }        free(buf);    }    for (ifrp = ifc.ifc_req;        (char *)ifrp < (char *)ifc.ifc_req + ifc.ifc_len;#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN        ifrp = (struct ifreq *)(((char *) ifrp) +                                sizeof(ifrp->ifr_name) +                                ifrp->ifr_addr.sa_len)#else        ifrp++#endif        ) {        if (ifrp->ifr_addr.sa_family != AF_INET) {            continue;        }        addr = ((struct sockaddr_in *) &(ifrp->ifr_addr))->sin_addr.s_addr;        if (ioctl(sd, SIOCGIFFLAGS, (char *) ifrp) < 0) {            continue;        }        if ((ifrp->ifr_flags & IFF_UP)#ifdef IFF_RUNNING            && (ifrp->ifr_flags & IFF_RUNNING)#endif                          /* IFF_RUNNING */            /*&& !(ifrp->ifr_flags & IFF_LOOPBACK)            && addr != LOOPBACK*/) {            /*             * I *really* don't understand why this is necessary.  Perhaps for             * some broken platform?  Leave it for now.  JBPN               */#ifdef SYS_IOCTL_H_HAS_SIOCGIFADDR            if (ioctl(sd, SIOCGIFADDR, (char *) ifrp) < 0) {                continue;            }            addr =                ((struct sockaddr_in *) &(ifrp->ifr_addr))->sin_addr.                s_addr;#endif            printf("current ip : %s\n",print_ip1(addr));        }    }    free(buf);    close(sd);    return 0;}int main(){    get_myaddr();}