1 files changed, 569 insertions, 206 deletions

diff --git a/src/lib/libc/net/gethostnamadr.c b/src/lib/libc/net/gethostnamadr.c
index 83e0225a65..9826b46805 100644
--- a/src/lib/libc/net/gethostnamadr.c
+++ b/src/lib/libc/net/gethostnamadr.c
@@ -52,7 +52,7 @@
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
-static char rcsid[] = "$OpenBSD: gethostnamadr.c,v 1.13 1997/01/30 05:56:06 deraadt Exp $";
+static char rcsid[] = "$OpenBSD: gethostnamadr.c,v 1.14 1997/03/13 19:07:24 downsj Exp $";
 #endif /* LIBC_SCCS and not lint */
 
 #include <sys/param.h>
@@ -66,6 +66,7 @@ static char rcsid[] = "$OpenBSD: gethostnamadr.c,v 1.13 1997/01/30 05:56:06 dera
 #include <ctype.h>
 #include <errno.h>
 #include <string.h>
+#include <syslog.h>
 #ifdef YP
 #include <rpc/rpc.h>
 #include <rpcsvc/yp.h>
@@ -73,6 +74,8 @@ static char rcsid[] = "$OpenBSD: gethostnamadr.c,v 1.13 1997/01/30 05:56:06 dera
 #include "ypinternal.h"
 #endif
 
+#define MULTI_PTRS_ARE_ALIASES 1        /* XXX - experimental */
+
 #define MAXALIASES      35
 #define MAXADDRS        35
 
@@ -85,10 +88,22 @@ static char *__ypdomain;
 static struct hostent host;
 static char *host_aliases[MAXALIASES];
 static char hostbuf[BUFSIZ+1];
-static struct in_addr host_addr;
+static u_char host_addr[16];            /* IPv4 or IPv6 */
 static FILE *hostf = NULL;
 static int stayopen = 0;
 
+static void map_v4v6_address __P((const char *src, char *dst));
+static void map_v4v6_hostent __P((struct hostent *hp, char **bp, int *len));
+
+#ifdef RESOLVSORT
+static void addrsort __P((char **, int));
+#endif
+
+static int hokchar __P((const char *));
+
+static const char AskedForGot[] =
+                          "gethostby*.getanswer: asked for \"%s\", got \"%s\"";
+
 #if PACKETSZ > 1024
 #define MAXPACKET       PACKETSZ
 #else
@@ -105,15 +120,14 @@ typedef union {
         char ac;
 } align;
 
-static int qcomp __P((struct in_addr **, struct in_addr **));
-static struct hostent *getanswer __P((querybuf *, int, int));
-static int hbadchar __P((char *));
+static struct hostent *getanswer __P((const querybuf *, int, const char *,
+                                      int));
 
 extern int h_errno;
 
 static int
-hbadchar(p)
-        char *p;
+hokchar(p)
+        const char *p;
 {
         char c;
 
@@ -121,7 +135,7 @@ hbadchar(p)
          * Many people do not obey RFC 822 and 1035.  The valid
          * characters are a-z, A-Z, 0-9, '-' and . But the others
          * tested for below can happen, and we must be more permissive
-         * until those idiots clean up their act.
+         * than the resolver until those idiots clean up their act.
          */
         while ((c = *p++)) {
                 if (('a' >= c && c <= 'z') ||
@@ -130,28 +144,50 @@ hbadchar(p)
                         continue;
                 if (strchr("-_/.[]\\", c) ||
                     (c == '.' && p[1] == '.'))
-                        return 1;
+                        return 0;
         }
-        return 0;
+        return 1;
 }
 
 static struct hostent *
-getanswer(answer, anslen, iquery)
-        querybuf *answer;
+getanswer(answer, anslen, qname, qtype)
+        const querybuf *answer;
         int anslen;
-        int iquery;
+        const char *qname;
+        int qtype;
 {
-        register HEADER *hp;
-        register u_char *cp;
+        register const HEADER *hp;
+        register const u_char *cp;
         register int n;
-        u_char *eom;
-        char *bp, **ap;
+        const u_char *eom;
+        char *bp, **ap, **hap;
         int type, class, buflen, ancount, qdcount;
-        int haveanswer, getclass = C_ANY;
-        char **hap;
-        int good = 1;
+        int haveanswer, had_error;
+        int toobig = 0;
+        char tbuf[MAXDNAME];
+        const char *tname;
+        int (*name_ok) __P((const char *));
 
+        tname = qname;
+        host.h_name = NULL;
         eom = answer->buf + anslen;
+        switch (qtype) {
+        case T_A:
+        case T_AAAA:
+#ifdef USE_RESOLV_NAME_OK
+                name_ok = res_hnok;
+                break;
+#endif
+        case T_PTR:
+#ifdef USE_RESOLV_NAME_OK
+                name_ok = res_dnok;
+#else
+                name_ok = hokchar;
+#endif
+                break;
+        default:
+                return (NULL);  /* XXX should be abort(); */
+        }
         /*
          * find first satisfactory answer
          */
@@ -159,34 +195,29 @@ getanswer(answer, anslen, iquery)
         ancount = ntohs(hp->ancount);
         qdcount = ntohs(hp->qdcount);
         bp = hostbuf;
-        buflen = sizeof(hostbuf);
-        cp = answer->buf + sizeof(HEADER);
-        if (qdcount) {
-                if (iquery) {
-                        if ((n = dn_expand((u_char *)answer->buf,
-                            (u_char *)eom, (u_char *)cp, bp,
-                            buflen)) < 0) {
-                                h_errno = NO_RECOVERY;
-                                return ((struct hostent *) NULL);
-                        }
-                        cp += n + QFIXEDSZ;
-                        host.h_name = bp;
-                        n = strlen(bp);
-                        if (n >= MAXHOSTNAMELEN)
-                                host.h_name[MAXHOSTNAMELEN-1] = '\0';
-                        n++;
-                        bp += n;
-                        buflen -= n;
-                } else
-                        cp += __dn_skipname(cp, eom) + QFIXEDSZ;
-                while (--qdcount > 0)
-                        cp += __dn_skipname(cp, eom) + QFIXEDSZ;
-        } else if (iquery) {
-                if (hp->aa)
-                        h_errno = HOST_NOT_FOUND;
-                else
-                        h_errno = TRY_AGAIN;
-                return ((struct hostent *) NULL);
+        buflen = sizeof hostbuf;
+        cp = answer->buf + HFIXEDSZ;
+        if (qdcount != 1) {
+                h_errno = NO_RECOVERY;
+                return (NULL);
+        }
+        n = dn_expand(answer->buf, eom, cp, bp, buflen);
+        if ((n < 0) || !(*name_ok)(bp)) {
+                h_errno = NO_RECOVERY;
+                return (NULL);
+        }
+        cp += n + QFIXEDSZ;
+        if (qtype == T_A || qtype == T_AAAA) {
+                /* res_send() has already verified that the query name is the
+                 * same as the one we sent; this just gets the expanded name
+                 * (i.e., with the succeeding search-domain tacked on).
+                 */
+                n = strlen(bp) + 1;             /* for the \0 */
+                host.h_name = bp;
+                bp += n;
+                buflen -= n;
+                /* The qname can be abbreviated, but h_name is now absolute. */
+                qname = host.h_name;
         }
         ap = host_aliases;
         *ap = NULL;
@@ -195,124 +226,258 @@ getanswer(answer, anslen, iquery)
         *hap = NULL;
         host.h_addr_list = h_addr_ptrs;
         haveanswer = 0;
-        if (ancount > MAXADDRS)
-                ancount = MAXADDRS;
-        while (--ancount >= 0 && cp < eom) {
-                if ((n = dn_expand((u_char *)answer->buf, (u_char *)eom,
-                    (u_char *)cp, bp, buflen)) < 0)
-                        break;
-                cp += n;
+        had_error = 0;
+        while (ancount-- > 0 && cp < eom && !had_error) {
+                n = dn_expand(answer->buf, eom, cp, bp, buflen);
+                if ((n < 0) || !(*name_ok)(bp)) {
+                        had_error++;
+                        continue;
+                }
+                cp += n;                        /* name */
                 type = _getshort(cp);
-                cp += sizeof(u_int16_t);
+                cp += INT16SZ;                  /* type */
                 class = _getshort(cp);
-                cp += sizeof(u_int16_t) + sizeof(u_int32_t);
+                cp += INT16SZ + INT32SZ;        /* class, TTL */
                 n = _getshort(cp);
-                cp += sizeof(u_int16_t);
-                if (type == T_CNAME) {
+                cp += INT16SZ;                  /* len */
+                if (class != C_IN) {
+                        /* XXX - debug? syslog? */
                         cp += n;
+                        continue;               /* XXX - had_error++ ? */
+                }
+                if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
                         if (ap >= &host_aliases[MAXALIASES-1])
                                 continue;
+                        n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
+                        if ((n < 0) || !(*name_ok)(tbuf)) {
+                                had_error++;
+                                continue;
+                        }
+                        cp += n;
+                        /* Store alias. */
                         *ap++ = bp;
-                        n = strlen(bp) + 1;
-                        if (n > MAXHOSTNAMELEN)
-                                bp[MAXHOSTNAMELEN-1] = '\0';
+                        n = strlen(bp) + 1;     /* for the \0 */
+                        bp += n;
+                        buflen -= n;
+                        /* Get canonical name. */
+                        n = strlen(tbuf) + 1;   /* for the \0 */
+                        if (n > buflen) {
+                                had_error++;
+                                continue;
+                        }
+                        strcpy(bp, tbuf);
+                        host.h_name = bp;
                         bp += n;
                         buflen -= n;
                         continue;
                 }
-                if (iquery && type == T_PTR) {
-                        if ((n = dn_expand((u_char *)answer->buf,
-                            (u_char *)eom, (u_char *)cp, bp,
-                            buflen)) < 0)
-                                break;
+                if (qtype == T_PTR && type == T_CNAME) {
+                        n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
+                        if ((n < 0) || !res_hnok(tbuf)) {
+                                had_error++;
+                                continue;
+                        }
                         cp += n;
-                        host.h_name = bp;
-                        n = strlen(host.h_name);
-                        if (n >= MAXHOSTNAMELEN)
-                                host.h_name[MAXHOSTNAMELEN-1] = '\0';
-                        goto gotent;
+                        /* Get canonical name. */
+                        n = strlen(tbuf) + 1;   /* for the \0 */
+                        if (n > buflen) {
+                                had_error++;
+                                continue;
+                        }
+                        strcpy(bp, tbuf);
+                        tname = bp;
+                        bp += n;
+                        buflen -= n;
+                        continue;
                 }
-                if (iquery || type != T_A)  {
-#ifdef DEBUG
-                        if (_res.options & RES_DEBUG)
-                                printf("unexpected answer type %d, size %d\n",
-                                        type, n);
-#endif
+                if (type != qtype) {
+                        syslog(LOG_NOTICE|LOG_AUTH,
+               "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
+                               qname, p_class(C_IN), p_type(qtype),
+                               p_type(type));
                         cp += n;
-                        continue;
+                        continue;               /* XXX - had_error++ ? */
                 }
-
-                if (haveanswer) {
-                        if (n != host.h_length) {
+                switch (type) {
+                case T_PTR:
+                        if (strcasecmp(tname, bp) != 0) {
+                                syslog(LOG_NOTICE|LOG_AUTH,
+                                       AskedForGot, qname, bp);
                                 cp += n;
-                                continue;
+                                continue;       /* XXX - had_error++ ? */
                         }
-                        if (class != getclass) {
+                        n = dn_expand(answer->buf, eom, cp, bp, buflen);
+                        if ((n < 0) || !res_hnok(bp)) {
+                                had_error++;
+                                break;
+                        }
+#if MULTI_PTRS_ARE_ALIASES
+                        cp += n;
+                        if (!haveanswer)
+                                host.h_name = bp;
+                        else if (ap < &host_aliases[MAXALIASES-1])
+                                *ap++ = bp;
+                        else
+                                n = -1;
+                        if (n != -1) {
+                                n = strlen(bp) + 1;     /* for the \0 */
+                                bp += n;
+                                buflen -= n;
+                        }
+                        break;
+#else
+                        host.h_name = bp;
+                        if (_res.options & RES_USE_INET6) {
+                                n = strlen(bp) + 1;     /* for the \0 */
+                                bp += n;
+                                buflen -= n;
+                                map_v4v6_hostent(&host, &bp, &buflen);
+                        }
+                        h_errno = NETDB_SUCCESS;
+                        return (&host);
+#endif
+                case T_A:
+                case T_AAAA:
+                        if (strcasecmp(host.h_name, bp) != 0) {
+                                syslog(LOG_NOTICE|LOG_AUTH,
+                                       AskedForGot, host.h_name, bp);
+                                cp += n;
+                                continue;       /* XXX - had_error++ ? */
+                        }
+                        if (n != host.h_length) {
                                 cp += n;
                                 continue;
                         }
-                } else {
-                        host.h_length = n;
-                        getclass = class;
-                        host.h_addrtype = (class == C_IN) ? AF_INET : AF_UNSPEC;
-                        if (host.h_addrtype == AF_INET)
-                                host.h_length = INADDRSZ;
-                        if (!iquery) {
+                        if (!haveanswer) {
+                                register int nn;
+
                                 host.h_name = bp;
-                                bp += strlen(bp) + 1;
-                                if (strlen(host.h_name) >= MAXHOSTNAMELEN)
-                                        host.h_name[MAXHOSTNAMELEN-1] = '\0';
+                                nn = strlen(bp) + 1;    /* for the \0 */
+                                bp += nn;
+                                buflen -= nn;
                         }
-                }
 
-                bp += sizeof(align) - ((u_long)bp % sizeof(align));
+                        bp += sizeof(align) - ((u_long)bp % sizeof(align));
 
-                if (bp + n >= &hostbuf[sizeof(hostbuf)]) {
+                        if (bp + n >= &hostbuf[sizeof hostbuf]) {
+#ifdef DEBUG
+                                if (_res.options & RES_DEBUG)
+                                        printf("size (%d) too big\n", n);
+#endif
+                                had_error++;
+                                continue;
+                        }
+                        if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
+                                if (!toobig++)
 #ifdef DEBUG
-                        if (_res.options & RES_DEBUG)
-                                printf("size (%d) too big\n", n);
+                                        if (_res.options & RES_DEBUG)
+                                                printf("Too many addresses (%d)\n", MAXADDRS);
 #endif
+                                cp += n;
+                                continue;
+                        }
+                        bcopy(cp, *hap++ = bp, n);
+                        bp += n;
+                        buflen -= n;
+                        cp += n;
                         break;
+                default:
+                        abort();
                 }
-                bcopy(cp, *hap++ = bp, n);
-                bp +=n;
-                cp += n;
-                haveanswer++;
-        }
-        if (!haveanswer) {
-                h_errno = TRY_AGAIN;
-                return ((struct hostent *) NULL);
-        }
-        *ap = NULL;
-        *hap = NULL;
-        if (_res.nsort) {
-                qsort(host.h_addr_list, haveanswer,
-                    sizeof(struct in_addr),
-                    (int (*)__P((const void *, const void *)))qcomp);
+                if (!had_error)
+                        haveanswer++;
         }
-gotent:
-        if (hbadchar(host.h_name))
-                good = 0;
-        for (ap = host_aliases; good && *ap; ap++)
-                if (hbadchar(*ap))
-                        good = 0;
-        if (good)
+        if (haveanswer) {
+                *ap = NULL;
+                *hap = NULL;
+# if defined(RESOLVSORT)
+                /*
+                 * Note: we sort even if host can take only one address
+                 * in its return structures - should give it the "best"
+                 * address in that case, not some random one
+                 */
+                if (_res.nsort && haveanswer > 1 && qtype == T_A)
+                        addrsort(h_addr_ptrs, haveanswer);
+# endif /*RESOLVSORT*/
+                if (!host.h_name) {
+                        n = strlen(qname) + 1;  /* for the \0 */
+                        if (n > buflen)
+                                goto try_again;
+                        strcpy(bp, qname);
+                        host.h_name = bp;
+                        bp += n;
+                        buflen -= n;
+                }
+                if (_res.options & RES_USE_INET6)
+                        map_v4v6_hostent(&host, &bp, &buflen);
+                h_errno = NETDB_SUCCESS;
                 return (&host);
-        h_errno = NO_RECOVERY;
-        return ((struct hostent *) NULL);
+        }
+ try_again:
+        h_errno = TRY_AGAIN;
+        return (NULL);
 }
 
 struct hostent *
 gethostbyname(name)
         const char *name;
 {
+        struct hostent *hp;
+        extern struct hostent *_gethtbyname2();
+
+        if ((_res.options & RES_INIT) == 0 && res_init() == -1)
+                return (_gethtbyname2(name, AF_INET));
+
+        if (_res.options & RES_USE_INET6) {
+                hp = gethostbyname2(name, AF_INET6);
+                if (hp)
+                        return (hp);
+        }
+        return (gethostbyname2(name, AF_INET));
+}
+
+struct hostent *
+gethostbyname2(name, af)
+        const char *name;
+        int af;
+{
         querybuf buf;
         register const char *cp;
-        int n, i;
-        extern struct hostent *_gethtbyname(), *_yp_gethtbyname();
+        char *bp;
+        int n, size, type, len, i;
+        extern struct hostent *_gethtbyname2(), *_yp_gethtbyname();
         register struct hostent *hp;
         char lookups[MAXDNSLUS];
 
+        if ((_res.options & RES_INIT) == 0 && res_init() == -1)
+                return (_gethtbyname2(name, af));
+
+        switch (af) {
+        case AF_INET:
+                size = INADDRSZ;
+                type = T_A;
+                break;
+        case AF_INET6:
+                size = IN6ADDRSZ;
+                type = T_AAAA;
+                break;
+        default:
+                h_errno = NETDB_INTERNAL;
+                errno = EAFNOSUPPORT;
+                return (NULL);
+        }
+
+        host.h_addrtype = af;
+        host.h_length = size;
+
+        /*
+         * if there aren't any dots, it could be a user-level alias.
+         * this is also done in res_query() since we are not the only
+         * function that looks up host names.
+         */
+        if (!strchr(name, '.') && (cp = __hostalias(name)))
+                name = cp;
+
         /*
          * disallow names consisting only of digits/dots, unless
          * they end in a dot.
@@ -327,26 +492,58 @@ gethostbyname(name)
                                  * Fake up a hostent as if we'd actually
                                  * done a lookup.
                                  */
-                                if (!inet_aton(name, &host_addr)) {
+                                if (inet_pton(af, name, host_addr) <= 0) {
                                         h_errno = HOST_NOT_FOUND;
-                                        return((struct hostent *) NULL);
+                                        return (NULL);
                                 }
-                                host.h_name = (char *)name;
+                                strncpy(hostbuf, name, MAXDNAME);
+                                hostbuf[MAXDNAME] = '\0';
+                                bp = hostbuf + MAXDNAME;
+                                len = sizeof hostbuf - MAXDNAME;
+                                host.h_name = hostbuf;
                                 host.h_aliases = host_aliases;
                                 host_aliases[0] = NULL;
-                                host.h_addrtype = AF_INET;
-                                host.h_length = sizeof(u_int32_t);
-                                h_addr_ptrs[0] = (char *)&host_addr;
+                                h_addr_ptrs[0] = (char *)host_addr;
                                 h_addr_ptrs[1] = NULL;
                                 host.h_addr_list = h_addr_ptrs;
+                                if (_res.options & RES_USE_INET6)
+                                        map_v4v6_hostent(&host, &bp, &len);
+                                h_errno = NETDB_SUCCESS;
                                 return (&host);
                         }
                         if (!isdigit(*cp) && *cp != '.') 
                                 break;
                 }
-
-        if ((_res.options & RES_INIT) == 0 && res_init() == -1)
-                return (_gethtbyname(name));
+        if (isxdigit(name[0]) || name[0] == ':')
+                for (cp = name;; ++cp) {
+                        if (!*cp) {
+                                if (*--cp == '.')
+                                        break;
+                                /*
+                                 * All-IPv6-legal, no dot at the end.
+                                 * Fake up a hostent as if we'd actually
+                                 * done a lookup.
+                                 */
+                                if (inet_pton(af, name, host_addr) <= 0) {
+                                        h_errno = HOST_NOT_FOUND;
+                                        return (NULL);
+                                }
+                                strncpy(hostbuf, name, MAXDNAME);
+                                hostbuf[MAXDNAME] = '\0';
+                                bp = hostbuf + MAXDNAME;
+                                len = sizeof hostbuf - MAXDNAME;
+                                host.h_name = hostbuf;
+                                host.h_aliases = host_aliases;
+                                host_aliases[0] = NULL;
+                                h_addr_ptrs[0] = (char *)host_addr;
+                                h_addr_ptrs[1] = NULL;
+                                host.h_addr_list = h_addr_ptrs;
+                                h_errno = NETDB_SUCCESS;
+                                return (&host);
+                        }
+                        if (!isxdigit(*cp) && *cp != ':' && *cp != '.') 
+                                break;
+                }
 
         bcopy(_res.lookups, lookups, sizeof lookups);
         if (lookups[0] == '\0')
@@ -357,11 +554,13 @@ gethostbyname(name)
                 switch (lookups[i]) {
 #ifdef YP
                 case 'y':
-                        hp = _yp_gethtbyname(name);
+                        /* YP only suports AF_INET. */
+                        if (af == AF_INET)
+                                hp = _yp_gethtbyname(name);
                         break;
 #endif
                 case 'b':
-                        if ((n = res_search(name, C_IN, T_A, buf.buf,
+                        if ((n = res_search(name, C_IN, type, buf.buf,
                             sizeof(buf))) < 0) {
 #ifdef DEBUG
                                 if (_res.options & RES_DEBUG)
@@ -369,10 +568,10 @@ gethostbyname(name)
 #endif
                                 break;
                         }
-                        hp = getanswer(&buf, n, 0);
+                        hp = getanswer(&buf, n, name, type);
                         break;
                 case 'f':
-                        hp = _gethtbyname(name);
+                        hp = _gethtbyname2(name, af);
                         break;
                 }
         }
@@ -380,27 +579,69 @@ gethostbyname(name)
 }
 
 struct hostent *
-gethostbyaddr(addr, len, type)
-        const char *addr;
-        int len, type;
+gethostbyaddr(addr, len, af)
+        const char *addr;       /* XXX should have been def'd as u_char! */
+        int len, af;
 {
-        int n, i;
+        const u_char *uaddr = (const u_char *)addr;
+        static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
+        static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
+        int n, size, i;
         querybuf buf;
         register struct hostent *hp;
-        char qbuf[MAXDNAME];
+        char qbuf[MAXDNAME+1], *qp;
         extern struct hostent *_gethtbyaddr(), *_yp_gethtbyaddr();
         char lookups[MAXDNSLUS];
         
-        if (type != AF_INET)
-                return ((struct hostent *) NULL);
-        (void)sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
-                ((unsigned)addr[3] & 0xff),
-                ((unsigned)addr[2] & 0xff),
-                ((unsigned)addr[1] & 0xff),
-                ((unsigned)addr[0] & 0xff));
-
         if ((_res.options & RES_INIT) == 0 && res_init() == -1)
-                return (_gethtbyaddr(addr, len, type));
+                return (_gethtbyaddr(addr, len, af));
+
+        if (af == AF_INET6 && len == IN6ADDRSZ &&
+            (!bcmp(uaddr, mapped, sizeof mapped) ||
+             !bcmp(uaddr, tunnelled, sizeof tunnelled))) {
+                /* Unmap. */
+                addr += sizeof mapped;
+                uaddr += sizeof mapped;
+                af = AF_INET;
+                len = INADDRSZ;
+        }
+        switch (af) {
+        case AF_INET:
+                size = INADDRSZ;
+                break;
+        case AF_INET6:
+                size = IN6ADDRSZ;
+                break;
+        default:
+                errno = EAFNOSUPPORT;
+                h_errno = NETDB_INTERNAL;
+                return (NULL);
+        }
+        if (size != len) {
+                errno = EINVAL;
+                h_errno = NETDB_INTERNAL;
+                return (NULL);
+        }
+        switch (af) {
+        case AF_INET:
+                (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
+                               (uaddr[3] & 0xff),
+                               (uaddr[2] & 0xff),
+                               (uaddr[1] & 0xff),
+                               (uaddr[0] & 0xff));
+                break;
+        case AF_INET6:
+                qp = qbuf;
+                for (n = IN6ADDRSZ - 1; n >= 0; n--) {
+                        qp += sprintf(qp, "%x.%x.",
+                                       uaddr[n] & 0xf,
+                                       (uaddr[n] >> 4) & 0xf);
+                }
+                strcpy(qp, "ip6.int");
+                break;
+        default:
+                abort();
+        }
 
         bcopy(_res.lookups, lookups, sizeof lookups);
         if (lookups[0] == '\0')
@@ -411,29 +652,38 @@ gethostbyaddr(addr, len, type)
                 switch (lookups[i]) {
 #ifdef YP
                 case 'y':
-                        hp = _yp_gethtbyaddr(addr);
+                        /* YP only supports AF_INET. */
+                        if (af == AF_INET)
+                                hp = _yp_gethtbyaddr(addr);
                         break;
 #endif
                 case 'b':
-                        n = res_query(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf));
+                        n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf.buf,
+                            sizeof buf.buf);
                         if (n < 0) {
 #ifdef DEBUG
                                 if (_res.options & RES_DEBUG)
                                         printf("res_query failed\n");
 #endif
-                                break;
+                                return (NULL);
                         }
-                        hp = getanswer(&buf, n, 1);
-                        if (hp == NULL)
-                                break;
-                        hp->h_addrtype = type;
+                        if (!(hp = getanswer(&buf, n, qbuf, T_PTR)))
+                                return (NULL);  /* h_errno was set by getanswer() */
+                        hp->h_addrtype = af;
                         hp->h_length = len;
-                        h_addr_ptrs[0] = (char *)&host_addr;
-                        h_addr_ptrs[1] = (char *)0;
-                        host_addr = *(struct in_addr *)addr;
+                        bcopy(addr, host_addr, len);
+                        h_addr_ptrs[0] = (char *)host_addr;
+                        h_addr_ptrs[1] = NULL;
+                        if (af == AF_INET && (_res.options & RES_USE_INET6)) {
+                                map_v4v6_address((char*)host_addr,
+                                    (char*)host_addr);
+                                hp->h_addrtype = AF_INET6;
+                                hp->h_length = IN6ADDRSZ;
+                        }
+                        h_errno = NETDB_SUCCESS;
                         break;
                 case 'f':
-                        hp = _gethtbyaddr(addr, len, type);
+                        hp = _gethtbyaddr(addr, len, af);
                         break;
                 }
         }
@@ -465,35 +715,51 @@ _gethtent()
 {
         char *p;
         register char *cp, **q;
+        int af, len;
 
-        if (hostf == NULL && (hostf = fopen(_PATH_HOSTS, "r" )) == NULL)
+        if (!hostf && !(hostf = fopen(_PATH_HOSTS, "r" ))) {
+                h_errno = NETDB_INTERNAL;
                 return (NULL);
-again:
-        if ((p = fgets(hostbuf, BUFSIZ, hostf)) == NULL)
+        }
+ again:
+        if (!(p = fgets(hostbuf, sizeof hostbuf, hostf))) {
+                h_errno = HOST_NOT_FOUND;
                 return (NULL);
+        }
         if (*p == '#')
                 goto again;
-        cp = strpbrk(p, "#\n");
-        if (cp == NULL)
+        if (!(cp = strpbrk(p, "#\n")))
                 goto again;
         *cp = '\0';
-        cp = strpbrk(p, " \t");
-        if (cp == NULL)
+        if (!(cp = strpbrk(p, " \t")))
                 goto again;
         *cp++ = '\0';
-        /* THIS STUFF IS INTERNET SPECIFIC */
-        h_addr_ptrs[0] = (char *)&host_addr;
+        if ((_res.options & RES_USE_INET6) &&
+            inet_pton(AF_INET6, p, host_addr) > 0) {
+                af = AF_INET6;
+                len = IN6ADDRSZ;
+        } else if (inet_pton(AF_INET, p, host_addr) > 0) {
+                if (_res.options & RES_USE_INET6) {
+                        map_v4v6_address((char*)host_addr, (char*)host_addr);
+                        af = AF_INET6;
+                        len = IN6ADDRSZ;
+                } else {
+                        af = AF_INET;
+                        len = INADDRSZ;
+                }
+        } else {
+                goto again;
+        }
+        h_addr_ptrs[0] = (char *)host_addr;
         h_addr_ptrs[1] = NULL;
-        (void) inet_aton(p, &host_addr);
         host.h_addr_list = h_addr_ptrs;
-        host.h_length = sizeof(u_int32_t);
-        host.h_addrtype = AF_INET;
+        host.h_length = len;
+        host.h_addrtype = af;
         while (*cp == ' ' || *cp == '\t')
                 cp++;
         host.h_name = cp;
         q = host.h_aliases = host_aliases;
-        cp = strpbrk(cp, " \t");
-        if (cp != NULL) 
+        if (cp = strpbrk(cp, " \t"))
                 *cp++ = '\0';
         while (cp && *cp) {
                 if (*cp == ' ' || *cp == '\t') {
@@ -502,11 +768,17 @@ again:
                 }
                 if (q < &host_aliases[MAXALIASES - 1])
                         *q++ = cp;
-                cp = strpbrk(cp, " \t");
-                if (cp != NULL)
+                if (cp = strpbrk(cp, " \t"))
                         *cp++ = '\0';
         }
         *q = NULL;
+        if (_res.options & RES_USE_INET6) {
+                char *bp = hostbuf;
+                int buflen = sizeof hostbuf;
+
+                map_v4v6_hostent(&host, &bp, &buflen);
+        }
+        h_errno = NETDB_SUCCESS;
         return (&host);
 }
 
@@ -514,58 +786,55 @@ struct hostent *
 _gethtbyname(name)
         const char *name;
 {
+        extern struct hostent *_gethtbyname2();
+        struct hostent *hp;
+
+        if (_res.options & RES_USE_INET6) {
+                hp = _gethtbyname2(name, AF_INET6);
+                if (hp)
+                        return (hp);
+        }
+        return (_gethtbyname2(name, AF_INET));
+}
+
+struct hostent *
+_gethtbyname2(name, af)
+        const char *name;
+        int af;
+{
         register struct hostent *p;
         register char **cp;
         
         _sethtent(0);
         while (p = _gethtent()) {
+                if (p->h_addrtype != af)
+                        continue;
                 if (strcasecmp(p->h_name, name) == 0)
                         break;
                 for (cp = p->h_aliases; *cp != 0; cp++)
                         if (strcasecmp(*cp, name) == 0)
                                 goto found;
         }
-found:
+ found:
         _endhtent();
-        if (p==NULL)
-                h_errno = HOST_NOT_FOUND;
         return (p);
 }
 
 struct hostent *
-_gethtbyaddr(addr, len, type)
+_gethtbyaddr(addr, len, af)
         const char *addr;
-        int len, type;
+        int len, af;
 {
         register struct hostent *p;
 
         _sethtent(0);
         while (p = _gethtent())
-                if (p->h_addrtype == type && !bcmp(p->h_addr, addr, len))
+                if (p->h_addrtype == af && !bcmp(p->h_addr, addr, len))
                         break;
         _endhtent();
-        if (p==NULL)
-                h_errno = HOST_NOT_FOUND;
         return (p);
 }
 
-static int
-qcomp(a1, a2)
-        struct in_addr **a1, **a2;
-{
-        int pos1, pos2;
-
-        for (pos1 = 0; pos1 < _res.nsort; pos1++)
-                if (_res.sort_list[pos1].addr.s_addr ==
-                    ((*a1)->s_addr & _res.sort_list[pos1].mask))
-                        break;
-        for (pos2 = 0; pos2 < _res.nsort; pos2++)
-                if (_res.sort_list[pos2].addr.s_addr ==
-                    ((*a2)->s_addr & _res.sort_list[pos2].mask))
-                        break;
-        return pos1 - pos2;
-}
-
 #ifdef YP
 struct hostent *
 _yphostent(line)
@@ -687,10 +956,104 @@ _yp_gethtbyname(name)
         __ypcurrent = NULL;
         r = yp_match(__ypdomain, "hosts.byname", name,
                 strlen(name), &__ypcurrent, &__ypcurrentlen);
-        if (r==0)
+        if (r == 0)
                 hp = _yphostent(__ypcurrent);
-        if (hp==NULL)
+        if (hp == NULL)
                 h_errno = HOST_NOT_FOUND;
         return (hp);
 }
 #endif
+
+static void
+map_v4v6_address(src, dst)
+        const char *src;
+        char *dst;
+{
+        u_char *p = (u_char *)dst;
+        char tmp[INADDRSZ];
+        int i;
+
+        /* Stash a temporary copy so our caller can update in place. */
+        bcopy(src, tmp, INADDRSZ);
+        /* Mark this ipv6 addr as a mapped ipv4. */
+        for (i = 0; i < 10; i++)
+                *p++ = 0x00;
+        *p++ = 0xff;
+        *p++ = 0xff;
+        /* Retrieve the saved copy and we're done. */
+        bcopy(tmp, (void*)p, INADDRSZ);
+}
+
+static void
+map_v4v6_hostent(hp, bpp, lenp)
+        struct hostent *hp;
+        char **bpp;
+        int *lenp;
+{
+        char **ap;
+
+        if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
+                return;
+        hp->h_addrtype = AF_INET6;
+        hp->h_length = IN6ADDRSZ;
+        for (ap = hp->h_addr_list; *ap; ap++) {
+                int i = sizeof(align) - ((u_long)*bpp % sizeof(align));
+
+                if (*lenp < (i + IN6ADDRSZ)) {
+                        /* Out of memory.  Truncate address list here.  XXX */
+                        *ap = NULL;
+                        return;
+                }
+                *bpp += i;
+                *lenp -= i;
+                map_v4v6_address(*ap, *bpp);
+                *ap = *bpp;
+                *bpp += IN6ADDRSZ;
+                *lenp -= IN6ADDRSZ;
+        }
+}
+
+#ifdef RESOLVSORT
+static void
+addrsort(ap, num)
+        char **ap;
+        int num;
+{
+        int i, j;
+        char **p;
+        short aval[MAXADDRS];
+        int needsort = 0;
+
+        p = ap;
+        for (i = 0; i < num; i++, p++) {
+            for (j = 0 ; (unsigned)j < _res.nsort; j++)
+                if (_res.sort_list[j].addr.s_addr == 
+                    (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
+                        break;
+            aval[i] = j;
+            if (needsort == 0 && i > 0 && j < aval[i-1])
+                needsort = i;
+        }
+        if (!needsort)
+            return;
+
+        while (needsort < num) {
+            for (j = needsort - 1; j >= 0; j--) {
+                if (aval[j] > aval[j+1]) {
+                    char *hp;
+
+                    i = aval[j];
+                    aval[j] = aval[j+1];
+                    aval[j+1] = i;
+
+                    hp = ap[j];
+                    ap[j] = ap[j+1];
+                    ap[j+1] = hp;
+
+                } else
+                    break;
+            }
+            needsort++;
+        }
+}
+#endif