dns/common/gethostent6.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * This is the DNS backend for IPv6 addresses.
 * getbyname() is a local routine, but getbyaddr() actually shares the
 * same codes as the one in gethostent.c.
 */

#define endhostent  res_endhostent

#include <malloc.h>
#include <stddef.h>
#include <string.h>
#include "dns_common.h"

/*
 * If the DNS name service switch routines are used in a binary that depends
 * on an older libresolv (libresolv.so.1, say), then having nss_dns.so.1 or
 * libnss_dns.a depend on a newer libresolv (libresolv.so.2) will cause
 * relocation problems. In particular, copy relocation of the _res structure
 * (which changes in size from libresolv.so.1 to libresolv.so.2) could
 * cause corruption, and result in a number of strange problems, including
 * core dumps. Hence, we check if a libresolv is already loaded.
 */


#pragma weak    res_endhostent

extern struct hostent *_gethostbyname(int *, const char *);
extern struct hostent *_nss_dns_gethostbyname2(int *, const char *);

typedef union {
    long al;
    char ac;
} align;


static void
_endhostent(errp)
    nss_status_t    *errp;
{
    int ret;

    ret = endhostent();
    if (ret == 0)
        *errp = NSS_SUCCESS;
    else
        *errp = NSS_UNAVAIL;
}


#ifdef  RNDUP
#undef  RNDUP
#endif
#define RNDUP(x)    ((1 + (((x)-1)/sizeof (void *))) * sizeof (void *))

#ifdef  PTROFF
#undef  PTROFF
#endif
#define PTROFF(p, o)    (((o) == 0) ? 0 : (void *)((char *)(p) + (o)))


/*
 * Make a copy of h->h_name.
 */
static char *
cloneName(struct hostent *h, int *outerr) {

    char    *name;
    int len;
    int error, *errp;

    if (outerr)
        errp = outerr;
    else
        errp = &error;

    if (h == 0 || h->h_name == 0) {
        *errp = 0;
        return (0);
    }

    len = strlen(h->h_name);

    if ((name = malloc(len+1)) == 0) {
        *errp = 1;
        return (0);
    }

    (void) memcpy(name, h->h_name, len+1);

    *errp = 0;
    return (name);
}


/*
 * Copy the h->h_addr_list[] array to a new array, and append the
 * moreAddrs[] list. If h->h_addr_list[] contains IPv4 addresses,
 * convert them to v4 mapped IPv6 addresses.
 *
 * Note: The pointers to the addresses in the moreAddrs[] array are copied,
 *       but not the IP addresses themselves.
 */
static struct in6_addr **
cloneAddrList(struct hostent *h, struct in6_addr **moreAddrs, int *outerr) {

    struct in6_addr **addrArray, *addrList;
    int     domap, addrlen, i, j, addrCount, moreAddrCount = 0;

    int error, *errp;

    if (outerr)
        errp = outerr;
    else
        errp = &error;

    if (h == 0 || h->h_addr_list == 0) {
        *errp = 0;
        return (0);
    }

    /* Should we map v4 to IPv6 ? */
    domap = (h->h_length == sizeof (struct in_addr)) &&
        (h->h_addrtype == AF_INET);

    /* If mapping, make sure we allocate enough memory for addresses */
    addrlen = h->h_length;
    if (domap && addrlen < sizeof (struct in6_addr))
        addrlen = sizeof (struct in6_addr);

    for (addrCount = 0; h->h_addr_list[addrCount]; addrCount++);

    if (moreAddrs != 0) {
        for (moreAddrCount = 0; moreAddrs[moreAddrCount];
            moreAddrCount++);
    }

    if ((addrArray = malloc((addrCount+moreAddrCount+1)*sizeof (addrList) +
                addrCount*addrlen)) == 0) {
        *errp = 1;
        return (0);
    }

    addrList = PTROFF(addrArray, (addrCount+moreAddrCount+1) *
                    sizeof (addrList));

    for (i = 0; i < addrCount; i++) {
        addrArray[i] = addrList;
        if (domap) {
            /* LINTED: E_BAD_PTR_CAST_ALIGN */
            IN6_INADDR_TO_V4MAPPED(
            (struct in_addr *)h->h_addr_list[i], addrArray[i]);
        } else {
            (void) memcpy(addrArray[i], h->h_addr_list[i],
                addrlen);
        }
        addrList = PTROFF(addrList, addrlen);
    }

    for (j = 0; j < moreAddrCount; j++, i++) {
        addrArray[i] = moreAddrs[j];
    }

    /* Last pointer should be NULL */
    addrArray[i] = 0;

    *errp = 0;
    return (addrArray);
}


/*
 * Create a new alias array that is is a copy of h->h_aliases[] plus
 * the aliases in mergeAliases[] which aren't duplicates of any alias
 * in h->h_aliases[].
 *
 * Note 1: Only the string pointers (NOT the strings) in the mergeAliases[]
 *         array are copied.
 *
 * Note 2: The duplicate aliases in mergeAliases[] are replaced by NULL
 *         pointers.
 */
static char **
cloneAliasList(struct hostent *h, char **mergeAliases, int *outerr) {

    char    **aliasArray, *aliasList;
    int i, j, aliasCount, mergeAliasCount = 0, realMac = 0;
    int stringSize = 0;
    int error, *errp;

    if (outerr)
        errp = outerr;
    else
        errp = &error;


    if (h == 0 || h->h_aliases == 0) {
        *errp = 0;
        return (0);
    }

    for (aliasCount = 0; h->h_aliases[aliasCount]; aliasCount++) {
        stringSize += RNDUP(strlen(h->h_aliases[aliasCount])+1);
    }

    if (mergeAliases != 0) {
        for (; mergeAliases[mergeAliasCount]; mergeAliasCount++) {
            int countThis = 1;
            /* Skip duplicates */
            for (j = 0; j < aliasCount; j++) {
                if (strcmp(mergeAliases[mergeAliasCount],
                        h->h_aliases[j]) == 0) {
                    countThis = 0;
                    break;
                }
            }
            if (countThis)
                realMac++;
            else
                mergeAliases[mergeAliasCount] = 0;
        }
    }

    if ((aliasArray = malloc((aliasCount+realMac+1)*sizeof (char **)+
                stringSize)) == 0) {
        *errp = 1;
        return (0);
    }

    aliasList = PTROFF(aliasArray,
                (aliasCount+realMac+1)*sizeof (char **));
    for (i = 0; i < aliasCount; i++) {
        int len = strlen(h->h_aliases[i]);
        aliasArray[i] = aliasList;
        (void) memcpy(aliasArray[i], h->h_aliases[i], len+1);
        aliasList = PTROFF(aliasList, RNDUP(len+1));
    }

    for (j = 0; j < mergeAliasCount; j++) {
        if (mergeAliases[j] != 0) {
            aliasArray[i++] = mergeAliases[j];
        }
    }

    aliasArray[i] = 0;

    *errp = 0;
    return (aliasArray);
}

/*ARGSUSED*/
static nss_status_t
getbyname(be, a)
    dns_backend_ptr_t   be;
    void            *a;
{
    struct hostent  *he = NULL;
    nss_XbyY_args_t *argp = (nss_XbyY_args_t *)a;
    int     ret, mt_disabled;
    sigset_t    oldmask;
    int     converr = 0, gotv6 = 0;
    struct hostent  v6he;
    struct hostent  mhe;
    char        *v6Name = 0;
    struct in6_addr **v6Addrs = 0, **mergeAddrs = 0;
    char        **v6Aliases = 0, **mergeAliases = 0;
    int     v6_h_errno;
    int     old_retry;
    int     af = argp->key.ipnode.af_family;
    int     flags = argp->key.ipnode.flags;

    switch_resolver_setup(&mt_disabled, &oldmask, &old_retry);

    /* Now get the AAAA records */
    if (af == AF_INET6)
        he = _nss_dns_gethostbyname2(&argp->h_errno,
                    argp->key.ipnode.name);
    if (he != NULL) {
        /*
         * pointer in "he" is part of a static pthread key in libresolv
         * It should be treated as read only.
         * So clone a copy first.
         */
        v6Name = cloneName(he, &converr);
        if (converr) {
            argp->h_errno = HOST_NOT_FOUND;
            argp->erange = 1;
            switch_resolver_reset(mt_disabled, oldmask, old_retry);
            return (_herrno2nss(argp->h_errno));
        }
        v6Addrs = cloneAddrList(he, 0, &converr);
        if (converr) {
            if (v6Name != 0)
                free(v6Name);
            argp->h_errno = HOST_NOT_FOUND;
            argp->erange = 1;
            switch_resolver_reset(mt_disabled, oldmask, old_retry);
            return (_herrno2nss(argp->h_errno));
        }
        v6Aliases = cloneAliasList(he, 0, &converr);
        if (converr) {
            if (v6Name != 0)
                free(v6Name);
            if (v6Addrs != 0)
                free(v6Addrs);
            argp->h_errno = HOST_NOT_FOUND;
            argp->erange = 1;
            switch_resolver_reset(mt_disabled, oldmask, old_retry);
            return (_herrno2nss(argp->h_errno));
        }
        v6_h_errno = argp->h_errno;
        gotv6 = 1;
    }

    /*
     * The conditions to search "A" records:
     * 1. af is AF_INET
     * 2. if af is AF_INET6
     *    then flags are either
     *  1) (AI_ALL | AI_V4MAPPED) or
     *  2) AI_V4MAPPED and he == NULL
     *      (No V6 addresses found or no search for V6 at all)
     */

    /* Get the A records, and store the information */
    if ((af == AF_INET) ||
        ((af == AF_INET6) &&
        ((flags & (AI_ALL | AI_V4MAPPED)) ||
        ((flags & AI_V4MAPPED) && he == NULL))))
        he = _gethostbyname(&argp->h_errno, argp->key.ipnode.name);
    else
        he = NULL;

    /* Merge the results */
    if (he != NULL) {
        mhe = *he;
        mergeAddrs = cloneAddrList(he, v6Addrs, &converr);
        if (converr) {
            if (v6Name != 0)
                free(v6Name);
            if (v6Addrs != 0)
                free(v6Addrs);
            if (v6Aliases != 0)
                free(v6Aliases);
            argp->h_errno = HOST_NOT_FOUND;
            argp->erange = 1;
            switch_resolver_reset(mt_disabled, oldmask,
                        old_retry);
            return (_herrno2nss(argp->h_errno));
        }
        mhe.h_addr_list = (char **)mergeAddrs;

        mergeAliases = cloneAliasList(he, v6Aliases, &converr);
        if (converr) {
            if (v6Name != 0)
                free(v6Name);
            if (v6Addrs != 0)
                free(v6Addrs);
            if (v6Aliases != 0)
                free(v6Aliases);
            if (mergeAddrs != 0)
                free(mergeAddrs);
            argp->h_errno = HOST_NOT_FOUND;
            argp->erange = 1;
            switch_resolver_reset(mt_disabled, oldmask,
                        old_retry);
            return (_herrno2nss(argp->h_errno));
        }
        mhe.h_aliases = mergeAliases;

        /* reset h_length, h_addrtype */
        mhe.h_length = sizeof (struct in6_addr);
        mhe.h_addrtype = AF_INET6;
        he = &mhe;

    } else if (gotv6) {
        v6he.h_name = v6Name;
        v6he.h_length = sizeof (struct in6_addr);
        v6he.h_addrtype = AF_INET6;
        v6he.h_addr_list = (char **)v6Addrs;
        v6he.h_aliases = v6Aliases;
        he = &v6he;
        argp->h_errno = v6_h_errno;
    }

    if (he != NULL) {
        /*
         * if asked to return data in string,
         * convert the hostent structure into
         * string data
         */
        if (argp->buf.result == NULL) {
            ret = ent2str(he, a, AF_INET6);
            if (ret == NSS_STR_PARSE_SUCCESS)
                argp->returnval = argp->buf.buffer;
        } else {
            ret = ent2result(he, a, AF_INET6);
            if (ret == NSS_STR_PARSE_SUCCESS)
                argp->returnval = argp->buf.result;
        }

        if (ret != NSS_STR_PARSE_SUCCESS) {
            argp->h_errno = HOST_NOT_FOUND;
            if (ret == NSS_STR_PARSE_ERANGE) {
                argp->erange = 1;
            }
        }
    }

    if (v6Name != 0)
        free(v6Name);
    if (v6Addrs != 0)
        free(v6Addrs);
    if (v6Aliases != 0)
        free(v6Aliases);
    if (mergeAddrs != 0)
        free(mergeAddrs);
    if (mergeAliases != 0)
        free(mergeAliases);

    switch_resolver_reset(mt_disabled, oldmask, old_retry);

    return (_herrno2nss(argp->h_errno));
}


extern nss_status_t __nss_dns_getbyaddr(dns_backend_ptr_t, void *);

static nss_status_t
getbyaddr(be, a)
    dns_backend_ptr_t   be;
    void            *a;
{
    /* uses the same getbyaddr from IPv4 */
    return (__nss_dns_getbyaddr(be, a));
}


/*ARGSUSED*/
static nss_status_t
_nss_dns_getent(be, args)
    dns_backend_ptr_t   be;
    void            *args;
{
    return (NSS_UNAVAIL);
}


/*ARGSUSED*/
static nss_status_t
_nss_dns_setent(be, dummy)
    dns_backend_ptr_t   be;
    void            *dummy;
{
    /* XXXX not implemented at this point */
    return (NSS_UNAVAIL);
}


/*ARGSUSED*/
static nss_status_t
_nss_dns_endent(be, dummy)
    dns_backend_ptr_t   be;
    void            *dummy;
{
    /* XXXX not implemented at this point */
    return (NSS_UNAVAIL);
}


/*ARGSUSED*/
static nss_status_t
_nss_dns_destr(be, dummy)
    dns_backend_ptr_t   be;
    void            *dummy;
{
    nss_status_t    errp;

    if (be != 0) {
        /* === Should change to invoke ops[ENDENT] ? */
        sigset_t    oldmask, newmask;
        int     mt_disabled = 1;

        if (enable_mt == 0 || (mt_disabled = (*enable_mt)()) != 0) {
            (void) sigfillset(&newmask);
            (void) thr_sigsetmask(SIG_SETMASK, &newmask, &oldmask);
            (void) mutex_lock(&one_lane);
        }

        _endhostent(&errp);

        if (mt_disabled) {
            (void) mutex_unlock(&one_lane);
            (void) thr_sigsetmask(SIG_SETMASK, &oldmask, NULL);
        } else {
            (void) (*disable_mt)();
        }

        free(be);
    }
    return (NSS_SUCCESS);   /* In case anyone is dumb enough to check */
}


static dns_backend_op_t ipnodes_ops[] = {
    _nss_dns_destr,
    _nss_dns_endent,
    _nss_dns_setent,
    _nss_dns_getent,
    getbyname,
    getbyaddr,
};

/*ARGSUSED*/
nss_backend_t *
_nss_dns_ipnodes_constr(dummy1, dummy2, dummy3)
    const char  *dummy1, *dummy2, *dummy3;
{
    return (_nss_dns_constr(ipnodes_ops,
        sizeof (ipnodes_ops) / sizeof (ipnodes_ops[0])));
}

/*
 * optional NSS2 packed backend gethostsbyipnode with ttl
 * entry point.
 *
 * Returns:
 *  NSS_SUCCESS - successful
 *  NSS_NOTFOUND - successful but nothing found
 *  NSS_ERROR - fallback to NSS backend lookup mode
 * If successful, buffer will be filled with valid data
 *
 */

/*ARGSUSED*/
nss_status_t
_nss_get_dns_ipnodes_name(dns_backend_ptr_t *be, void **bufp, size_t *sizep)
{
    return (_nss_dns_gethost_withttl(*bufp, *sizep, 1));
}