dns/common/gethostent.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"

/*
 * gethostent.c
 *
 * In order to avoid duplicating libresolv code here, and since libresolv.so.2
 * provides res_-equivalents of the getXbyY and {set,get}Xent, lets call
 * re_gethostbyaddr() and so on from this file. Among other things, this
 * should help us avoid problems like the one described in bug 1264386,
 * where the internal getanswer() acquired new functionality in BIND 4.9.3,
 * but the local copy of getanswer() in this file wasn't updated, so that new
 * functionality wasn't available to the name service switch.
 */

#define gethostbyaddr   res_gethostbyaddr
#define gethostbyname   res_gethostbyname
#define gethostbyname2  res_gethostbyname2
#define sethostent  res_sethostent
#define endhostent  res_endhostent

#include "dns_common.h"

extern char *inet_ntoa(struct in_addr in);

struct hostent *_gethostbyname(int *h_errnop, const char *name);
static struct hostent *_gethostbyaddr(int *h_errnop, const char *addr,
    int len, int type);
struct hostent *_nss_dns_gethostbyname2(int *h_errnop, const char *name);

#pragma weak    res_gethostbyname
#pragma weak    res_gethostbyname2
#pragma weak    res_gethostbyaddr
#pragma weak    res_sethostent
#pragma weak    res_endhostent

nss_backend_t *_nss_dns_constr(dns_backend_op_t ops[], int n_ops);
nss_status_t __nss_dns_getbyaddr(dns_backend_ptr_t, void *);

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

/*
 * Internet Name Domain Server (DNS) only implementation.
 */
static struct hostent *
_gethostbyaddr(int *h_errnop, const char *addr, int len, int type)
{
    struct hostent  *hp;

    hp = gethostbyaddr(addr, len, type);
    *h_errnop = *get_h_errno();
    return (hp);
}

struct hostent *
_nss_dns_gethostbyname2(int *h_errnop, const char *name)
{
    struct hostent *hp;

    hp = gethostbyname2(name, AF_INET6);
    *h_errnop = *get_h_errno();
    return (hp);
}

struct hostent *
_gethostbyname(int *h_errnop, const char *name)
{
    struct hostent *hp;

    hp = gethostbyname(name);
    *h_errnop = *get_h_errno();
    return (hp);
}

static void
_sethostent(errp, stayopen)
    nss_status_t    *errp;
    int     stayopen;
{
    int ret;

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

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

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


/*ARGSUSED*/
static nss_status_t
getbyname(be, a)
    dns_backend_ptr_t   be;
    void            *a;
{
    struct hostent  *he;
    nss_XbyY_args_t *argp = (nss_XbyY_args_t *)a;
    int     ret, mt_disabled;
    int     old_retry;
    sigset_t    oldmask;

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

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

    switch_resolver_reset(mt_disabled, oldmask, old_retry);

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


/*ARGSUSED*/
static nss_status_t
getbyaddr(be, a)
    dns_backend_ptr_t   be;
    void            *a;
{
    return (__nss_dns_getbyaddr(be, a));
}


/*
 * Exposing a DNS backend specific interface so that it doesn't conflict
 * with other getbyaddr() routines from other switch backends.
 */
/*ARGSUSED*/
nss_status_t
__nss_dns_getbyaddr(be, a)
    dns_backend_ptr_t   be;
    void            *a;
{
    struct hostent  *he;
    nss_XbyY_args_t *argp = (nss_XbyY_args_t *)a;
    int     ret, mt_disabled;
    struct in_addr  unmapv4;
    sigset_t    oldmask;
    int     af, addrlen;
    void        *addrp;
    int     old_retry;

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

    /* LINTED: E_BAD_PTR_CAST_ALIGN */
    if (IN6_IS_ADDR_V4MAPPED((struct in6_addr *)argp->key.hostaddr.addr)) {
        addrp = &unmapv4;
        addrlen = sizeof (unmapv4);
        af = AF_INET;
        (void) memcpy(addrp, &argp->key.hostaddr.addr[12], addrlen);
    } else {
        addrp = (void *)argp->key.hostaddr.addr;
        addrlen = argp->key.hostaddr.len;
        af = argp->key.hostaddr.type;
    }
    he = _gethostbyaddr(&argp->h_errno, addrp, addrlen, af);

    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, argp->key.hostaddr.type);
        else
            ret = ent2result(he, a, argp->key.hostaddr.type);

        if (ret == NSS_STR_PARSE_SUCCESS) {
            if (argp->buf.result == NULL)
                argp->returnval = argp->buf.buffer;
            else
                argp->returnval = argp->buf.result;
        } else {
            argp->h_errno = HOST_NOT_FOUND;
            if (ret == NSS_STR_PARSE_ERANGE)
                argp->erange = 1;
        }
    }

    switch_resolver_reset(mt_disabled, oldmask, old_retry);

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


/*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;
{
    nss_status_t    errp;

    sigset_t    oldmask, newmask;
    int     mt_disabled = 1;

    /*
     * Try to enable MT; if not, we have to single-thread libresolv
     * access
     */
    if (enable_mt == 0 || (mt_disabled = (*enable_mt)()) != 0) {
        (void) sigfillset(&newmask);
        (void) thr_sigsetmask(SIG_SETMASK, &newmask, &oldmask);
        (void) mutex_lock(&one_lane);
    }

    _sethostent(&errp, 1);

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

    return (errp);
}


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

    sigset_t    oldmask, newmask;
    int     mt_disabled = 1;

    /*
     * Try to enable MT; if not, we have to single-thread libresolv
     * access
     */
    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)();
    }

    return (errp);
}


/*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 host_ops[] = {
    _nss_dns_destr,
    _nss_dns_endent,
    _nss_dns_setent,
    _nss_dns_getent,
    getbyname,
    getbyaddr,
};

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

/*
 * optional NSS2 packed backend gethostsbyname 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_hosts_name(dns_backend_ptr_t *be, void **bufp, size_t *sizep)
{
    return (_nss_dns_gethost_withttl(*bufp, *sizep, 0));
}