dns/common/dns_common.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 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * Copyright (c) 2013, Joyent, Inc.  All rights reserved.
 */

/*
 *  dns_common.c
 */

#include "dns_common.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <ifaddrs.h>
#include <net/if.h>

#pragma weak    dn_expand
#pragma weak    res_ninit
#pragma weak    res_ndestroy
#pragma weak    res_nsearch
#pragma weak    res_nclose
#pragma weak    ns_get16
#pragma weak    ns_get32
#pragma weak    __ns_get16
#pragma weak    __ns_get32

#define DNS_ALIASES 0
#define DNS_ADDRLIST    1
#define DNS_MAPDLIST    2

#ifndef tolower
#define tolower(c) ((c) >= 'A' && (c) <= 'Z' ? (c) | 0x20 : (c))
#endif

static int
dns_netdb_aliases(from_list, to_list, aliaspp, type, count, af_type)
    char    **from_list, **to_list, **aliaspp;
    int type, *count, af_type;
{
    char        *fstr;
    int     cnt = 0;
    size_t      len;

    *count = 0;
    if ((char *)to_list >= *aliaspp)
        return (NSS_STR_PARSE_ERANGE);

    for (fstr = from_list[cnt]; fstr != NULL; fstr = from_list[cnt]) {
        if (type == DNS_ALIASES)
            len = strlen(fstr) + 1;
        else
            len = (af_type == AF_INET) ? sizeof (struct in_addr)
                        : sizeof (struct in6_addr);
        *aliaspp -= len;
        to_list[cnt] = *aliaspp;
        if (*aliaspp <= (char *)&to_list[cnt+1])
            return (NSS_STR_PARSE_ERANGE);
        if (type == DNS_MAPDLIST) {
            /* LINTED: E_BAD_PTR_CAST_ALIGN */
            struct in6_addr *addr6p = (struct in6_addr *)*aliaspp;

            (void) memset(addr6p, '\0', sizeof (struct in6_addr));
            (void) memcpy(&addr6p->s6_addr[12], fstr,
                    sizeof (struct in_addr));
            addr6p->s6_addr[10] = 0xffU;
            addr6p->s6_addr[11] = 0xffU;
            ++cnt;
        } else {
            (void) memcpy (*aliaspp, fstr, len);
            ++cnt;
        }
    }
    to_list[cnt] = NULL;

    *count = cnt;
    if (cnt == 0)
        return (NSS_STR_PARSE_PARSE);

    return (NSS_STR_PARSE_SUCCESS);
}


int
ent2result(he, argp, af_type)
    struct hostent      *he;
    nss_XbyY_args_t     *argp;
    int         af_type;
{
    char        *buffer, *limit;
    int     buflen = argp->buf.buflen;
    int     ret, count;
    size_t len;
    struct hostent  *host;
    struct in_addr  *addrp;
    struct in6_addr *addrp6;

    limit = argp->buf.buffer + buflen;
    host = (struct hostent *)argp->buf.result;
    buffer = argp->buf.buffer;

    /* h_addrtype and h_length */
    host->h_addrtype = af_type;
    host->h_length = (af_type == AF_INET) ? sizeof (struct in_addr)
                    : sizeof (struct in6_addr);

    /* h_name */
    len = strlen(he->h_name) + 1;
    host->h_name = buffer;
    if (host->h_name + len >= limit)
        return (NSS_STR_PARSE_ERANGE);
    (void) memcpy(host->h_name, he->h_name, len);
    buffer += len;

    /* h_addr_list */
    if (af_type == AF_INET) {
        addrp = (struct in_addr *)ROUND_DOWN(limit, sizeof (*addrp));
        host->h_addr_list = (char **)
                ROUND_UP(buffer, sizeof (char **));
        ret = dns_netdb_aliases(he->h_addr_list, host->h_addr_list,
            (char **)&addrp, DNS_ADDRLIST, &count, af_type);
        if (ret != NSS_STR_PARSE_SUCCESS)
            return (ret);
        /* h_aliases */
        host->h_aliases = host->h_addr_list + count + 1;
        ret = dns_netdb_aliases(he->h_aliases, host->h_aliases,
            (char **)&addrp, DNS_ALIASES, &count, af_type);
    } else {
        addrp6 = (struct in6_addr *)
            ROUND_DOWN(limit, sizeof (*addrp6));
        host->h_addr_list = (char **)
            ROUND_UP(buffer, sizeof (char **));
        if (he->h_addrtype == AF_INET && af_type == AF_INET6) {
            ret = dns_netdb_aliases(he->h_addr_list,
                host->h_addr_list, (char **)&addrp6,
                DNS_MAPDLIST, &count, af_type);
        } else {
            ret = dns_netdb_aliases(he->h_addr_list,
                host->h_addr_list, (char **)&addrp6,
                DNS_ADDRLIST, &count, af_type);
        }
        if (ret != NSS_STR_PARSE_SUCCESS)
            return (ret);
        /* h_aliases */
        host->h_aliases = host->h_addr_list + count + 1;
        ret = dns_netdb_aliases(he->h_aliases, host->h_aliases,
            (char **)&addrp6, DNS_ALIASES, &count, af_type);
    }
    if (ret == NSS_STR_PARSE_PARSE)
        ret = NSS_STR_PARSE_SUCCESS;

    return (ret);
}

/*
 * Convert the hostent structure into string in the following
 * format:
 *
 * IP-address official-host-name nicknames ...
 *
 * If more than one IP-addresses matches the official-host-name,
 * the above line will be followed by:
 * IP-address-1 official-host-name
 * IP-address-2 official-host-name
 * ...
 *
 * This is so that the str2hostent function in libnsl
 * can convert the string back to the original hostent
 * data.
 */
int
ent2str(
    struct hostent  *hp,
    nss_XbyY_args_t *ap,
    int     af_type)
{
    char        **p;
    char        obuf[INET6_ADDRSTRLEN];
    void        *addr;
    struct in_addr  in4;
    int     af;
    int     n;
    const char  *res;
    char        **q;
    int     l = ap->buf.buflen;
    char        *s = ap->buf.buffer;

    /*
     * for "hosts" lookup, we only want address type of
     * AF_INET. For "ipnodes", we can have both AF_INET
     * and AF_INET6.
     */
    if (af_type == AF_INET && hp->h_addrtype != AF_INET)
        return (NSS_STR_PARSE_PARSE);

    for (p = hp->h_addr_list; *p != 0; p++) {

        if (p != hp->h_addr_list) {
            *s = '\n';
            s++;
            l--;
        }

        if (hp->h_addrtype == AF_INET6) {
            /* LINTED: E_BAD_PTR_CAST_ALIGN */
            if (IN6_IS_ADDR_V4MAPPED((struct in6_addr *)*p)) {
                /* LINTED: E_BAD_PTR_CAST_ALIGN */
                IN6_V4MAPPED_TO_INADDR((struct in6_addr *)*p,
                    &in4);
                af = AF_INET;
                addr = &in4;
            } else {
                af = AF_INET6;
                addr = *p;
            }
        } else {
            af = AF_INET;
            addr = *p;
        }
        res = inet_ntop(af, addr, obuf, sizeof (obuf));
        if (res == NULL)
            return (NSS_STR_PARSE_PARSE);

        if ((n = snprintf(s, l, "%s", res)) >= l)
            return (NSS_STR_PARSE_ERANGE);
        l -= n;
        s += n;
        if (hp->h_name != NULL && *hp->h_name != '\0') {
            if ((n = snprintf(s, l, " %s", hp->h_name)) >= l)
                return (NSS_STR_PARSE_ERANGE);
            l -= n;
            s += n;
        }
        if (p == hp->h_addr_list) {
            for (q = hp->h_aliases; q && *q; q++) {
                if ((n = snprintf(s, l, " %s", *q)) >= l)
                    return (NSS_STR_PARSE_ERANGE);
                l -= n;
                s += n;
            }
        }
    }

    ap->returnlen = s - ap->buf.buffer;
    return (NSS_STR_PARSE_SUCCESS);
}

nss_backend_t *
_nss_dns_constr(dns_backend_op_t ops[], int n_ops)
{
    dns_backend_ptr_t   be;

    if ((be = (dns_backend_ptr_t)malloc(sizeof (*be))) == 0)
        return (0);

    be->ops = ops;
    be->n_ops = n_ops;
    return ((nss_backend_t *)be);
}

/*
 * name_is_alias(aliases_ptr, name_ptr)
 * Verify name matches an alias in the provided aliases list.
 *
 * Within DNS there should be only one canonical name, aliases should
 * all refer to the one canonical.  However alias chains do occur and
 * pre BIND 9 servers may also respond with multiple CNAMEs.  This
 * routine checks if a given name has been provided as a CNAME in the
 * response.  This assumes that the chains have been sent in-order.
 *
 * INPUT:
 *  aliases_ptr: space separated list of alias names.
 *  name_ptr: name to look for in aliases_ptr list.
 * RETURNS: NSS_SUCCESS or NSS_NOTFOUND
 *  NSS_SUCCESS indicates that the name is listed in the collected aliases.
 */
static nss_status_t
name_is_alias(char *aliases_ptr, char *name_ptr) {
    char *host_ptr;
    /* Loop through alias string and compare it against host string. */
    while (*aliases_ptr != '\0') {
        host_ptr = name_ptr;

        /* Compare name with alias. */
        while (tolower(*host_ptr) == tolower(*aliases_ptr) &&
            *host_ptr != '\0') {
            host_ptr++;
            aliases_ptr++;
        }

        /*
         * If name was exhausted and the next character in the
         * alias is either the end-of-string or space
         * character then we have a match.
         */
        if (*host_ptr == '\0' &&
            (*aliases_ptr == '\0' || *aliases_ptr == ' ')) {
            return (NSS_SUCCESS);
        }

        /* Alias did not match, step over remainder of alias. */
        while (*aliases_ptr != ' ' && *aliases_ptr != '\0')
            aliases_ptr++;
        /* Step over separator character. */
        while (*aliases_ptr == ' ') aliases_ptr++;
    }
    return (NSS_NOTFOUND);
}

static int
_nss_has_interfaces(boolean_t *v4, boolean_t *v6)
{
    struct ifaddrs *ifp, *i;
    struct in_addr in4;
    struct in6_addr in6;
    const struct in6_addr in6addr_any = IN6ADDR_ANY_INIT;

    *v4 = *v6 = B_FALSE;

    if (getifaddrs(&ifp) != 0)
        return (-1);

    for (i = ifp; i != NULL; i = i->ifa_next) {
        if (i->ifa_flags & IFF_LOOPBACK)
            continue;
        if ((i->ifa_flags & IFF_UP) == 0)
            continue;

        if (i->ifa_addr->sa_family == AF_INET) {
            if (*v4 != B_FALSE)
                continue;

            if (((struct sockaddr_in *)i->ifa_addr)->
                sin_addr.s_addr == INADDR_ANY)
                continue;
            *v4 = B_TRUE;
        }

        if (i->ifa_addr->sa_family == AF_INET6) {
            if (*v6 != B_FALSE)
                continue;

            if (memcmp(&in6addr_any,
                &((struct sockaddr_in6 *)i->ifa_addr)->sin6_addr,
                sizeof (struct in6_addr)) == 0)
                continue;
            *v6 = B_TRUE;
        }
    }

    freeifaddrs(ifp);
    return (0);
}

/*
 * nss_dns_gethost_withttl(void *buffer, size_t bufsize, int ipnode)
 *      nss2 get hosts/ipnodes with ttl backend DNS search engine.
 *
 * This API is given a pointer to a packed buffer, and the buffer size
 * It's job is to perform the appropriate res_nsearch, extract the
 * results and build a unmarshalled hosts/ipnodes result buffer.
 * Additionally in the extended results a nssuint_t ttl is placed.
 * This ttl is the lessor of the ttl's extracted from the result.
 *
 * RETURNS:  NSS_SUCCESS or NSS_ERROR
 *  If an NSS_ERROR result is returned, nscd is expected
 *  to resubmit the gethosts request using the old style
 *  nsswitch lookup format.
 */

nss_status_t
_nss_dns_gethost_withttl(void *buffer, size_t bufsize, int ipnode)
{
    /* nss buffer variables */
    nss_pheader_t   *pbuf = (nss_pheader_t *)buffer;
    nss_XbyY_args_t arg;
    char        *dbname;
    int     dbop;
    nss_status_t    sret;
    size_t      bsize, blen;
    char        *bptr;
    /* resolver query variables */
    struct __res_state stat, *statp;    /* dns state block */
    union msg {
        uchar_t buf[NS_MAXMSG];     /* max legal DNS answer size */
        HEADER  h;
    } resbuf;
    char aliases[NS_MAXMSG];        /* set of aliases */
    const char  *name;
    int     qtype;
    /* answer parsing variables */
    HEADER      *hp;
    uchar_t     *cp;    /* current location in message */
    uchar_t     *bom;   /* start of message */
    uchar_t     *eom;   /* end of message */
    uchar_t     *eor;   /* end of record */
    int     ancount, qdcount;
    int     type, class;
    nssuint_t   nttl, ttl, *pttl;   /* The purpose of this API */
    int     n, ret;
    const char  *np;
    /* temporary buffers */
    char        nbuf[INET6_ADDRSTRLEN]; /* address parser */
    char        host[MAXHOSTNAMELEN];   /* result host name */
    char        ans[MAXHOSTNAMELEN];    /* record name */
    char        aname[MAXHOSTNAMELEN];  /* alias result (C_NAME) */
    /* misc variables */
    int     af;
    char        *ap, *apc;
    int     hlen = 0, alen, iplen, len, isans;
    boolean_t   has_v4 = B_FALSE, has_v6 = B_FALSE;
    int     flags, family, pass2 = 0;

    statp = &stat;
    (void) memset(statp, '\0', sizeof (struct __res_state));
    if (res_ninit(statp) == -1) {
        return (NSS_ERROR);
    }

    ap = apc = (char *)aliases;
    alen = 0;
    ttl = (nssuint_t)0xFFFFFFF;     /* start w/max, find smaller */

    /* save space for ttl otherwise, why bother... */
    bsize = pbuf->data_len - sizeof (nssuint_t);
    bptr = (char *)buffer + pbuf->data_off;
    blen = 0;
    sret = nss_packed_getkey(buffer, bufsize, &dbname, &dbop, &arg);
    if (sret != NSS_SUCCESS) {
        res_ndestroy(statp);
        return (NSS_ERROR);
    }

    /*
     * There may be flags set when we are handling ipnode. There are three
     * different values for flags:
     *
     *  o AI_V4MAPPED
     *  o AI_ALL
     *  o AI_ADDRCONFIG
     *
     * The first two only have a meaning when af_family is ipv6. The latter
     * means something in both cases. These flags are documented in
     * getipnodebyname(3SOCKET), though the combinations leave a little
     * something to be desired. It would be great if we could actually use
     * getipnodebyname directly here since it already knows how to handle
     * this kind of logic; however, we're not quite so lucky. Ideally we
     * would add such an interface to libresolv.so.2 to handle this kind of
     * thing, but that's rather painful as well. We'll summarize what has to
     * happen below:
     *
     * AI_ALL is only meaningful when AI_V4MAPPED is also specified. Both
     * are ignored if the family is not AF_INET6
     *
     * family == AF_INET, flags | AI_ADDRCONFIG
     *  - lookup A records iff we have v4 plumbed
     * family == AF_INET, !(flags | AI_ADDRCONFIG)
     *  - lookup A records
     * family == AF_INET6, flags == 0 || flags == AI_ALL
     *  - lookup AAAA records
     * family == AF_INET6, flags | AI_V4MAPPED
     *  - lookup AAAA, if none, lookup A
     * family == AF_INET6, flags | AI_ADDRCONFIG
     *  - lookup AAAA records if ipv6
     * family == AF_INET6, flags | AI_V4MAPPED && flags | AI_ALL
     *  - lookup AAAA records, lookup A records
     * family == AF_INET6, flags | AI_V4MAPPED && flags | AI_ADDRCONFIG
     *  - lookup AAAA records if ipv6
     *  - If no AAAA && ipv4 exists, lookup A
     * family == AF_INET6, flags | AI_V4MAPPED && flags | AI_ADDRCONFIG &&
     * flags | AI_ALL
     *  - lookup AAAA records if ipv6
     *  - loookup A records if ipv4
     */
    if (ipnode) {
        /* initially only handle the simple cases */
        name = arg.key.ipnode.name;
        flags = arg.key.ipnode.flags;
        family = arg.key.ipnode.af_family;
        if (flags != 0) {
            /*
             * Figure out our first pass. We'll determine if we need
             * to do a second pass afterwards once we successfully
             * finish our first pass.
             */
            if ((flags & AI_ADDRCONFIG) != 0) {
                if (_nss_has_interfaces(&has_v4, &has_v6) !=
                    0) {
                    res_ndestroy(statp);
                    return (NSS_ERROR);
                }
                /* Impossible situations... */
                if (family == AF_INET && has_v4 == B_FALSE) {
                    res_ndestroy(statp);
                    return (NSS_NOTFOUND);
                }
                if (family == AF_INET6 && has_v6 == B_FALSE &&
                    !(flags & AI_V4MAPPED)) {
                    res_ndestroy(statp);
                    return (NSS_NOTFOUND);
                }
                if (family == AF_INET6 && has_v6)
                    qtype = T_AAAA;
                if (family == AF_INET || (family == AF_INET6 &&
                    has_v6 == B_FALSE && flags & AI_V4MAPPED))
                    qtype = T_A;
            } else {
                has_v4 = has_v6 = B_TRUE;
                if (family == AF_INET6)
                    qtype = T_AAAA;
                else
                    qtype = T_A;
            }
        } else {
            if (family == AF_INET6)
                qtype = T_AAAA;
            else
                qtype = T_A;
        }
    } else {
        name = arg.key.name;
        qtype = T_A;
    }

searchagain:
    ret = res_nsearch(statp, name, C_IN, qtype, resbuf.buf, NS_MAXMSG);
    if (ret == -1) {
        /*
         * We want to continue on unless we got NO_RECOVERY. Otherwise,
         * HOST_NOT_FOUND, TRY_AGAIN, and NO_DATA all suggest to me that
         * we should keep going.
         */
        if (statp->res_h_errno == NO_RECOVERY) {
            /* else lookup error - handle in general code */
            res_ndestroy(statp);
            return (NSS_ERROR);
        }

        /*
         * We found something on our first pass. Make sure that we do
         * not clobber this information. This ultimately means that we
         * were successful.
         */
        if (pass2 == 2)
            goto out;

        /*
         * If we're on the second pass (eg. we need to check both for A
         * and AAAA records), or we were only ever doing a search for
         * one type of record and are not supposed to do a second pass,
         * then we need to return that we couldn't find anything to the
         * user.
         */
        if (pass2 == 1 || flags == 0 || family == AF_INET ||
            (family == AF_INET6 && !(flags & AI_V4MAPPED))) {
            pbuf->p_herrno = HOST_NOT_FOUND;
            pbuf->p_status = NSS_NOTFOUND;
            pbuf->data_len = 0;
            res_ndestroy(statp);
            return (NSS_NOTFOUND);
        }

        /*
         * If we were only requested to search for flags on an IPv6
         * interface or we have no IPv4 interface, we stick to only
         * doing a single pass and bail now.
         */
        if ((flags & AI_ADDRCONFIG) && !(flags & AI_ALL) &&
            has_v4 == B_FALSE) {
            pbuf->p_herrno = HOST_NOT_FOUND;
            pbuf->p_status = NSS_NOTFOUND;
            pbuf->data_len = 0;
            res_ndestroy(statp);
            return (NSS_NOTFOUND);
        }
        qtype = T_A;
        flags = 0;
        pass2 = 1;
        goto searchagain;
    }

    cp = resbuf.buf;
    hp = (HEADER *)&resbuf.h;
    bom = cp;
    eom = cp + ret;

    ancount = ntohs(hp->ancount);
    qdcount = ntohs(hp->qdcount);
    cp += HFIXEDSZ;
    if (qdcount != 1) {
        res_ndestroy(statp);
        return (NSS_ERROR);
    }
    n = dn_expand(bom, eom, cp, host, MAXHOSTNAMELEN);
    if (n < 0) {
        res_ndestroy(statp);
        return (NSS_ERROR);
    } else
        hlen = strlen(host);
    /* no host name is an error, return */
    if (hlen <= 0) {
        res_ndestroy(statp);
        return (NSS_ERROR);
    }
    cp += n + QFIXEDSZ;
    if (cp > eom) {
        res_ndestroy(statp);
        return (NSS_ERROR);
    }
    while (ancount-- > 0 && cp < eom && blen < bsize) {
        n = dn_expand(bom, eom, cp, ans, MAXHOSTNAMELEN);
        if (n > 0) {
            /*
             * Check that the expanded name is either the
             * name we asked for or a learned alias.
             */
            if ((isans = strncasecmp(host, ans, hlen)) != 0 &&
                (alen == 0 || name_is_alias(aliases, ans)
                == NSS_NOTFOUND)) {
                res_ndestroy(statp);
                return (NSS_ERROR); /* spoof? */
            }
        }
        cp += n;
        /* bounds check */
        type = ns_get16(cp);            /* type */
        cp += INT16SZ;
        class = ns_get16(cp);           /* class */
        cp += INT16SZ;
        nttl = (nssuint_t)ns_get32(cp);     /* ttl in sec */
        if (nttl < ttl)
            ttl = nttl;
        cp += INT32SZ;
        n = ns_get16(cp);           /* len */
        cp += INT16SZ;
        if (class != C_IN) {
            cp += n;
            continue;
        }
        eor = cp + n;
        if (type == T_CNAME) {
            /*
             * The name looked up is really an alias and the
             * canonical name should be in the RDATA.
             * A canonical name may have several aliases but an
             * alias should only have one canonical name.
             * However multiple CNAMEs and CNAME chains do exist!
             *
             * Just error out on attempted buffer overflow exploit,
             * generic code will syslog.
             *
             */
            n = dn_expand(bom, eor, cp, aname, MAXHOSTNAMELEN);
            if (n > 0 && (len = strlen(aname)) > 0) {
                if (isans == 0) { /* host matched ans. */
                    /*
                     * Append host to alias list.
                     */
                    if (alen + hlen + 2 > NS_MAXMSG) {
                        res_ndestroy(statp);
                        return (NSS_ERROR);
                    }
                    *apc++ = ' ';
                    alen++;
                    (void) strlcpy(apc, host,
                        NS_MAXMSG - alen);
                    alen += hlen;
                    apc += hlen;
                }
                /*
                 * Overwrite host with canonical name.
                 */
                if (strlcpy(host, aname, MAXHOSTNAMELEN) >=
                    MAXHOSTNAMELEN) {
                    res_ndestroy(statp);
                    return (NSS_ERROR);
                }
                hlen = len;
            }
            cp += n;
            continue;
        }
        if (type != qtype) {
            cp += n;
            continue;
        }
        /* check data size */
        if ((type == T_A && n != INADDRSZ) ||
            (type == T_AAAA && n != IN6ADDRSZ)) {
            cp += n;
            continue;
        }
        af = (type == T_A ? AF_INET : AF_INET6);
        np = inet_ntop(af, (void *)cp, nbuf, INET6_ADDRSTRLEN);
        if (np == NULL) {
            res_ndestroy(statp);
            return (NSS_ERROR);
        }
        cp += n;
        /* append IP host aliases to results */
        iplen = strlen(np);
        /* ip <SP> hostname [<SP>][aliases] */
        len = iplen + 2 + hlen + alen;
        if (alen > 0)
            len++;
        if (blen + len > bsize) {
            res_ndestroy(statp);
            return (NSS_ERROR);
        }
        (void) strlcpy(bptr, np, bsize - blen);
        blen += iplen;
        bptr += iplen;
        *bptr++ = ' ';
        blen++;
        (void) strlcpy(bptr, host, bsize - blen);
        blen += hlen;
        bptr += hlen;
        if (alen > 0) {
            *bptr++ = ' ';
            blen++;
            (void) strlcpy(bptr, ap, bsize - blen);
            blen += alen;
            bptr += alen;
        }
        *bptr++ = '\n';
        blen++;
    }

    /* Depending on our flags we may need to go back another time. */
    if (qtype == T_AAAA && family == AF_INET6 &&
        ((flags & AI_V4MAPPED) != 0) && ((flags & AI_ALL) != 0) &&
        has_v4 == B_TRUE) {
        qtype = T_A;
        pass2 = 2; /* Indicate that we found data this pass */
        goto searchagain;
    }

    /* Presumably the buffer is now filled. */
    len = ROUND_UP(blen, sizeof (nssuint_t));
    /* still room? */
    if (len + sizeof (nssuint_t) > pbuf->data_len) {
        /* sigh, no, what happened? */
        res_ndestroy(statp);
        return (NSS_ERROR);
    }
out:
    pbuf->ext_off = pbuf->data_off + len;
    pbuf->ext_len = sizeof (nssuint_t);
    pbuf->data_len = blen;
    pttl = (nssuint_t *)((void *)((char *)pbuf + pbuf->ext_off));
    *pttl = ttl;
    res_ndestroy(statp);
    return (NSS_SUCCESS);
}