isc/unix/ifiter_ioctl.c

	ifiter_ioctl.c revision 27e48d2eea8a6231697719dbaca341603072c89d
/*
 * Copyright (C) 1999  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

/*
 * Obtain the list of network interfaces using the SIOCGIFCONF ioctl.
 * See netintro(4).
 */

#define IFITER_MAGIC        0x49464954U /* IFIT. */
#define VALID_IFITER(t)     ((t) != NULL && (t)->magic == IFITER_MAGIC)

struct isc_interfaceiter {
    unsigned int        magic;      /* Magic number. */
    isc_mem_t       *mctx;
    int         socket;
    struct ifconf       ifc;
    void            *buf;       /* Buffer for sysctl data. */
    unsigned int        bufsize;    /* Bytes allocated. */
    unsigned int        pos;        /* Current offset in
                           SIOCGIFCONF data */
    isc_interface_t     current;    /* Current interface data. */
    isc_result_t        result;     /* Last result code. */
};


/*
 * Size of buffer for SIOCGIFCONF, in bytes.  We assume no sane system
 * will have more than a megabyte of interface configuration data.
 */
#define IFCONF_BUFSIZE_INITIAL  4096
#define IFCONF_BUFSIZE_MAX  1048576

isc_result_t
isc_interfaceiter_create(isc_mem_t *mctx, isc_interfaceiter_t **iterp)
{
    isc_interfaceiter_t *iter;
    isc_result_t result;

    REQUIRE(mctx != NULL);
    REQUIRE(iterp != NULL);
    REQUIRE(*iterp == NULL);

    iter = isc_mem_get(mctx, sizeof(*iter));
    if (iter == NULL)
        return (ISC_R_NOMEMORY);

    iter->mctx = mctx;
    iter->buf = NULL;

    /* Create an unbound datagram socket to do the SIOCGIFADDR ioctl on. */
    if ((iter->socket = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "making interface scan socket: %s",
                 strerror(errno));
        result = ISC_R_UNEXPECTED;
        goto socket_failure;
    }

    /*
     * Get the interface configuration, allocating more memory if
     * necessary.
     */
    iter->bufsize = IFCONF_BUFSIZE_INITIAL;

    for (;;) {
        iter->buf = isc_mem_get(mctx, iter->bufsize);
        if (iter->buf == NULL) {
            result = ISC_R_NOMEMORY;
            goto alloc_failure;
        }

        iter->ifc.ifc_len = iter->bufsize;
        iter->ifc.ifc_buf = iter->buf;
        if (ioctl(iter->socket, SIOCGIFCONF, (char *) &iter->ifc) < 0) {
            if (errno != EINVAL) {
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                         "get interface configuration: %s",
                         strerror(errno));
                result = ISC_R_UNEXPECTED;
                goto ioctl_failure;
            }
            /* EINVAL.  Retry with a bigger buffer. */
        } else {
            /*
             * The ioctl succeeded.
             * Some OS's just return what will fit rather
             * than set EINVAL if the buffer is too small
             * to fit all the interfaces in.  If
             * ifc.ifc_len is too near to the end of the
             * buffer we will grow it just in case and
             * retry.
             */
            if (iter->ifc.ifc_len + 2 * sizeof(struct ifreq)
                < iter->bufsize)
                break;
        }
        if (iter->bufsize >= IFCONF_BUFSIZE_MAX) {
            UNEXPECTED_ERROR(__FILE__, __LINE__,
                     "get interface configuration: "
                     "maximum buffer size exceeded");
            result = ISC_R_UNEXPECTED;
            goto ioctl_failure;
        }
        isc_mem_put(mctx, iter->buf, iter->bufsize);

        iter->bufsize *= 2;
    }

    /*
     * A newly created iterator has an undefined position
     * until isc_interfaceiter_first() is called.
     */
    iter->pos = (unsigned int) -1;
    iter->result = ISC_R_FAILURE;

    iter->magic = IFITER_MAGIC;
    *iterp = iter;
    return (ISC_R_SUCCESS);

 ioctl_failure:
    isc_mem_put(mctx, iter->buf, iter->bufsize);

 alloc_failure:
    (void) close(iter->socket);

 socket_failure:
    isc_mem_put(mctx, iter, sizeof *iter);
    return (result);
}

/*
 * Get information about the current interface to iter->current.
 * If successful, return ISC_R_SUCCESS.
 * If the interface has an unsupported address family,
 * return ISC_R_FAILURE.  In case of other failure,
 * return ISC_R_UNEXPECTED.
 */

static isc_result_t
internal_current(isc_interfaceiter_t *iter) {
    struct ifreq *ifrp;
    struct ifreq ifreq;
    int family;

    REQUIRE(VALID_IFITER(iter));
    REQUIRE (iter->pos < (unsigned int) iter->ifc.ifc_len);

    ifrp = (struct ifreq *)((char *) iter->ifc.ifc_req + iter->pos);

    memcpy(&ifreq, ifrp, sizeof ifreq);

    family = ifreq.ifr_addr.sa_family;
    if (family != AF_INET) /* XXX IPv6 */
        return (ISC_R_FAILURE);

    memset(&iter->current, 0, sizeof(iter->current));

    INSIST(sizeof(ifreq.ifr_name) <= sizeof(iter->current.name));
    memcpy(iter->current.name, ifreq.ifr_name, sizeof(ifreq.ifr_name));

    get_addr(family, &iter->current.address, &ifreq.ifr_addr);

    /* Get interface flags. */

    iter->current.flags = 0;

    if (ioctl(iter->socket, SIOCGIFFLAGS, (char *) &ifreq) < 0) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "%s: getting interface flags: %s",
                 ifreq.ifr_name,
                 strerror(errno));
        return (ISC_R_UNEXPECTED);
    }

    if ((ifreq.ifr_flags & IFF_UP) != 0)
        iter->current.flags |= INTERFACE_F_UP;

    if ((ifreq.ifr_flags & IFF_POINTOPOINT) != 0)
        iter->current.flags |= INTERFACE_F_POINTTOPOINT;

    if ((ifreq.ifr_flags & IFF_LOOPBACK) != 0)
        iter->current.flags |= INTERFACE_F_LOOPBACK;

    /* If the interface is point-to-point, get the destination address. */
    if ((iter->current.flags & INTERFACE_F_POINTTOPOINT) != 0) {
        if (ioctl(iter->socket, SIOCGIFDSTADDR, (char *) &ifreq) < 0) {
            UNEXPECTED_ERROR(__FILE__, __LINE__,
                     "%s: getting destination address: %s",
                     ifreq.ifr_name,
                     strerror(errno));
            return (ISC_R_UNEXPECTED);
        }
        get_addr(family, &iter->current.dstaddress,
             &ifreq.ifr_dstaddr);
    }

    /* Get the network mask. */
    if (ioctl(iter->socket, SIOCGIFNETMASK, (char *) &ifreq) < 0) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "%s: getting netmask: %s",
                 ifreq.ifr_name,
                 strerror(errno));
        return (ISC_R_UNEXPECTED);
    }
    get_addr(family, &iter->current.netmask,
         &ifreq.ifr_addr);

    return (ISC_R_SUCCESS);
}

/*
 * Step the iterator to the next interface.  Unlike
 * isc_interfaceiter_next(), this may leave the iterator
 * positioned on an interface that will ultimately
 * be ignored.  Return ISC_R_NOMORE if there are no more
 * interfaces, otherwise ISC_R_SUCCESS.
 */
static isc_result_t
internal_next(isc_interfaceiter_t *iter) {
    struct ifreq *ifrp;

    REQUIRE (iter->pos < (unsigned int) iter->ifc.ifc_len);

    ifrp = (struct ifreq *)((char *) iter->ifc.ifc_req + iter->pos);

#ifdef ISC_NET_HAVESALEN
    if (ifrp->ifr_addr.sa_len > sizeof(struct sockaddr))
        iter->pos += sizeof(ifrp->ifr_name) + ifrp->ifr_addr.sa_len;
    else
#endif
        iter->pos += sizeof *ifrp;

    if (iter->pos >= (unsigned int) iter->ifc.ifc_len)
        return (ISC_R_NOMORE);

    return (ISC_R_SUCCESS);
}

static void
internal_destroy(isc_interfaceiter_t *iter) {
    (void) close(iter->socket);
}