ifiter_sysctl.c

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/*
 * Copyright (C) 2004, 2005, 2007, 2014  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1999-2003  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC 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.
 */

/* $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>

/* 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;
}

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