isc/unix/ifiter_sysctl.c

/*
 * Copyright (C) 1999-2005, 2007, 2014-2016  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

/* $Id: ifiter_sysctl.c,v 1.25 2007/06/19 23:47:18 tbox Exp $ */

/*! \file
 * \brief
 * Obtain the list of network interfaces using sysctl.
 * See TCP/IP Illustrated Volume 2, sections 19.8, 19.14,
 * and 19.16.
 */

#include <sys/param.h>
#include <sys/sysctl.h>

#include <net/route.h>
#include <net/if_dl.h>

#include <isc/print.h>

/* XXX what about Alpha? */
#ifdef sgi
#define ROUNDUP(a) ((a) > 0 ? \
        (1 + (((a) - 1) | (sizeof(__uint64_t) - 1))) : \
        sizeof(__uint64_t))
#else
#define ROUNDUP(a) ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) \
            : sizeof(long))
#endif

#define IFITER_MAGIC        ISC_MAGIC('I', 'F', 'I', 'S')
#define VALID_IFITER(t)     ISC_MAGIC_VALID(t, IFITER_MAGIC)

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

static int mib[6] = {
    CTL_NET,
    PF_ROUTE,
    0,
    0,          /* Any address family. */
    NET_RT_IFLIST,
    0           /* Flags. */
};

isc_result_t
isc_interfaceiter_create(isc_mem_t *mctx, isc_interfaceiter_t **iterp) {
    isc_interfaceiter_t *iter;
    isc_result_t result;
    size_t bufsize;
    size_t bufused;
    char strbuf[ISC_STRERRORSIZE];

    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 = 0;

    /*
     * Determine the amount of memory needed.
     */
    bufsize = 0;
    if (sysctl(mib, 6, NULL, &bufsize, NULL, (size_t) 0) < 0) {
        isc__strerror(errno, strbuf, sizeof(strbuf));
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 isc_msgcat_get(isc_msgcat,
                        ISC_MSGSET_IFITERSYSCTL,
                        ISC_MSG_GETIFLISTSIZE,
                        "getting interface "
                        "list size: sysctl: %s"),
                 strbuf);
        result = ISC_R_UNEXPECTED;
        goto failure;
    }
    iter->bufsize = bufsize;

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

    bufused = bufsize;
    if (sysctl(mib, 6, iter->buf, &bufused, NULL, (size_t) 0) < 0) {
        isc__strerror(errno, strbuf, sizeof(strbuf));
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 isc_msgcat_get(isc_msgcat,
                        ISC_MSGSET_IFITERSYSCTL,
                        ISC_MSG_GETIFLIST,
                        "getting interface list: "
                        "sysctl: %s"),
                 strbuf);
        result = ISC_R_UNEXPECTED;
        goto failure;
    }
    iter->bufused = bufused;
    INSIST(iter->bufused <= iter->bufsize);

    /*
     * 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);

 failure:
    if (iter->buf != NULL)
        isc_mem_put(mctx, iter->buf, iter->bufsize);
    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_IGNORE.  In case of other failure,
 * return ISC_R_UNEXPECTED.
 */

static isc_result_t
internal_current(isc_interfaceiter_t *iter) {
    struct ifa_msghdr *ifam, *ifam_end;

    REQUIRE(VALID_IFITER(iter));
    REQUIRE (iter->pos < (unsigned int) iter->bufused);

    ifam = (struct ifa_msghdr *) ((char *) iter->buf + iter->pos);
    ifam_end = (struct ifa_msghdr *) ((char *) iter->buf + iter->bufused);

    if (ifam->ifam_type == RTM_IFINFO) {
        struct if_msghdr *ifm = (struct if_msghdr *) ifam;
        struct sockaddr_dl *sdl = (struct sockaddr_dl *) (ifm + 1);
        unsigned int namelen;

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

        namelen = sdl->sdl_nlen;
        if (namelen > sizeof(iter->current.name) - 1)
            namelen = sizeof(iter->current.name) - 1;

        memset(iter->current.name, 0, sizeof(iter->current.name));
        memmove(iter->current.name, sdl->sdl_data, namelen);

        iter->current.flags = 0;

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

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

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

        /*
         * This is not an interface address.
         * Force another iteration.
         */
        return (ISC_R_IGNORE);
    } else if (ifam->ifam_type == RTM_NEWADDR) {
        int i;
        int family;
        struct sockaddr *mask_sa = NULL;
        struct sockaddr *addr_sa = NULL;
        struct sockaddr *dst_sa = NULL;

        struct sockaddr *sa = (struct sockaddr *)(ifam + 1);
        family = sa->sa_family;

        for (i = 0; i < RTAX_MAX; i++)
        {
            if ((ifam->ifam_addrs & (1 << i)) == 0)
                continue;

            INSIST(sa < (struct sockaddr *) ifam_end);

            switch (i) {
            case RTAX_NETMASK: /* Netmask */
                mask_sa = sa;
                break;
            case RTAX_IFA: /* Interface address */
                addr_sa = sa;
                break;
            case RTAX_BRD: /* Broadcast or destination address */
                dst_sa = sa;
                break;
            }
#ifdef ISC_PLATFORM_HAVESALEN
            sa = (struct sockaddr *)((char*)(sa)
                     + ROUNDUP(sa->sa_len));
#else
#ifdef sgi
            /*
             * Do as the contributed SGI code does.
             */
            sa = (struct sockaddr *)((char*)(sa)
                     + ROUNDUP(_FAKE_SA_LEN_DST(sa)));
#else
            /* XXX untested. */
            sa = (struct sockaddr *)((char*)(sa)
                     + ROUNDUP(sizeof(struct sockaddr)));
#endif
#endif
        }

        if (addr_sa == NULL)
            return (ISC_R_IGNORE);

        family = addr_sa->sa_family;
        if (family != AF_INET && family != AF_INET6)
            return (ISC_R_IGNORE);

        iter->current.af = family;

        get_addr(family, &iter->current.address, addr_sa,
             iter->current.name);

        if (mask_sa != NULL)
            get_addr(family, &iter->current.netmask, mask_sa,
                 iter->current.name);

        if (dst_sa != NULL &&
            (iter->current.flags & INTERFACE_F_POINTTOPOINT) != 0)
            get_addr(family, &iter->current.dstaddress, dst_sa,
                 iter->current.name);

        return (ISC_R_SUCCESS);
    } else {
        printf("%s",
               isc_msgcat_get(isc_msgcat, ISC_MSGSET_IFITERSYSCTL,
                      ISC_MSG_UNEXPECTEDTYPE,
                      "warning: unexpected interface list "
                      "message type\n"));
        return (ISC_R_IGNORE);
    }
}

/*
 * 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 ifa_msghdr *ifam;
    REQUIRE (iter->pos < (unsigned int) iter->bufused);

    ifam = (struct ifa_msghdr *) ((char *) iter->buf + iter->pos);

    iter->pos += ifam->ifam_msglen;

    if (iter->pos >= iter->bufused)
        return (ISC_R_NOMORE);

    return (ISC_R_SUCCESS);
}

static void
internal_destroy(isc_interfaceiter_t *iter) {
    UNUSED(iter); /* Unused. */
    /*
     * Do nothing.
     */
}

static
void internal_first(isc_interfaceiter_t *iter) {
    iter->pos = 0;
}