dns/common/dns_common.c

	dns_common.c revision c70a8a3b92fb0488ef2ca1ae9e282c8b86ffa6d1
/*
 * 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 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

/*
 *  dns_common.c
 */

#include "dns_common.h"

#pragma weak    dn_expand
#pragma weak    res_ninit
#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

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 %s", res, 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);
}


/*
 * 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.
 *
 * ***Currently the first version of this API only performs simple
 *    single res_nsearch lookups for with T_A or T_AAAA results.
 *    Other searches are deferred to the generic API w/t ttls.
 *
 *    This function is not a generic res_* operation.  It only performs
 *    a single T_A or T_AAAA lookups***
 *
 * 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, alen, iplen, len;

    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_nclose(statp);
        return (NSS_ERROR);
    }

    if (ipnode) {
        /* initially only handle the simple cases */
        if (arg.key.ipnode.flags != 0) {
            res_nclose(statp);
            return (NSS_ERROR);
        }
        name = arg.key.ipnode.name;
        if (arg.key.ipnode.af_family == AF_INET6)
            qtype = T_AAAA;
        else
            qtype = T_A;
    } else {
        name = arg.key.name;
        qtype = T_A;
    }
    ret = res_nsearch(statp, name, C_IN, qtype, resbuf.buf, NS_MAXMSG);
    if (ret == -1) {
        if (statp->res_h_errno == HOST_NOT_FOUND) {
            pbuf->p_herrno = HOST_NOT_FOUND;
            pbuf->p_status = NSS_NOTFOUND;
            pbuf->data_len = 0;
            res_nclose(statp);
            return (NSS_NOTFOUND);
        }
        /* else lookup error - handle in general code */
        res_nclose(statp);
        return (NSS_ERROR);
    }

    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_nclose(statp);
        return (NSS_ERROR);
    }
    n = dn_expand(bom, eom, cp, host, MAXHOSTNAMELEN);
    if (n < 0) {
        res_nclose(statp);
        return (NSS_ERROR);
    } else
        hlen = strlen(host);
    cp += n + QFIXEDSZ;
    if (cp > eom) {
        res_nclose(statp);
        return (NSS_ERROR);
    }
    while (ancount-- > 0 && cp < eom && blen < bsize) {
        n = dn_expand(bom, eom, cp, ans, MAXHOSTNAMELEN);
        if (n > 0) {
            if (strncasecmp(host, ans, hlen) != 0) {
                res_nclose(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) {
            /* add an alias to the alias list */
            n = dn_expand(bom, eor, cp, aname, MAXHOSTNAMELEN);
            if (n > 0) {
                len = strlen(aname);
                if (len > 0) {
                    /*
                     * Just error out if there is an
                     * attempted buffer overflow exploit
                     * generic code will do a syslog
                     */
                    if (alen + len + 2 > NS_MAXMSG)
                        return (NSS_ERROR);
                    *apc++ = ' ';
                    alen++;
                    (void) strlcpy(apc, aname, len + 1);
                    alen += len;
                    apc += 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_nclose(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)
            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++;
    }
    /* 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? */
        return (NSS_ERROR);
    }
    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_nclose(statp);
    return (NSS_SUCCESS);
}