resolv/compat-gethnamaddr.c

   1 /*
   2  * ++Copyright++ 1985, 1988, 1993
   3  * -
   4  * Copyright (c) 1985, 1988, 1993
   5  *    The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 4. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  * -
  31  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  32  *
  33  * Permission to use, copy, modify, and distribute this software for any
  34  * purpose with or without fee is hereby granted, provided that the above
  35  * copyright notice and this permission notice appear in all copies, and that
  36  * the name of Digital Equipment Corporation not be used in advertising or
  37  * publicity pertaining to distribution of the document or software without
  38  * specific, written prior permission.
  39  *
  40  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  41  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  42  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  43  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  44  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  45  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  46  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  47  * SOFTWARE.
  48  * -
  49  * --Copyright--
  50  */
  51
  52 /* XXX This file is not used by any of the resolver functions implemented by
  53    glibc (i.e. get*info and gethostby*).  It cannot be removed however because
  54    it exports symbols in the libresolv ABI.  The file is not maintained any
  55    more, nor are these functions.  */
  56
  57 #include <shlib-compat.h>
  58 #if SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_25)
  59
  60 # include <sys/types.h>
  61 # include <sys/param.h>
  62 # include <sys/socket.h>
  63 # include <netinet/in.h>
  64 # include <arpa/inet.h>
  65 # include <arpa/nameser.h>
  66
  67 # include <stdio.h>
  68 # include <netdb.h>
  69 # include <resolv/resolv-internal.h>
  70 # include <resolv/resolv_context.h>
  71 # include <ctype.h>
  72 # include <errno.h>
  73 # include <stdlib.h>
  74 # include <string.h>
  75
  76 # define        MAXALIASES      35
  77 # define        MAXADDRS        35
  78
  79 static char *h_addr_ptrs[MAXADDRS + 1];
  80
  81 static struct hostent host;
  82 static char *host_aliases[MAXALIASES];
  83 static char hostbuf[8*1024];
  84 static u_char host_addr[16];    /* IPv4 or IPv6 */
  85 static FILE *hostf = NULL;
  86 static int stayopen = 0;
  87
  88 static struct hostent *res_gethostbyname2_context (struct resolv_context *,
  89                                                    const char *name, int af);
  90
  91 static void map_v4v6_address (const char *src, char *dst) __THROW;
  92 static void map_v4v6_hostent (struct hostent *hp, char **bp, int *len) __THROW;
  93
  94 extern void addrsort (char **, int) __THROW;
  95
  96 # if PACKETSZ > 65536
  97 #  define       MAXPACKET       PACKETSZ
  98 # else
  99 #  define       MAXPACKET       65536
 100 # endif
 101
 102 /* As per RFC 1034 and 1035 a host name cannot exceed 255 octets in length.  */
 103 # ifdef MAXHOSTNAMELEN
 104 #  undef MAXHOSTNAMELEN
 105 # endif
 106 # define MAXHOSTNAMELEN 256
 107
 108 typedef union {
 109     HEADER hdr;
 110     u_char buf[MAXPACKET];
 111 } querybuf;
 112
 113 typedef union {
 114     int32_t al;
 115     char ac;
 116 } align;
 117
 118 # ifndef h_errno
 119 extern int h_errno;
 120 # endif
 121
 122 # ifdef DEBUG
 123 static void
 124 Dprintf (char *msg, int num)
 125 {
 126         if (_res.options & RES_DEBUG) {
 127                 int save = errno;
 128
 129                 printf(msg, num);
 130                 __set_errno (save);
 131         }
 132 }
 133 # else
 134 #  define Dprintf(msg, num) /*nada*/
 135 # endif
 136
 137 # define BOUNDED_INCR(x) \
 138         do { \
 139                 cp += x; \
 140                 if (cp > eom) { \
 141                         __set_h_errno (NO_RECOVERY); \
 142                         return (NULL); \
 143                 } \
 144         } while (0)
 145
 146 # define BOUNDS_CHECK(ptr, count) \
 147         do { \
 148                 if ((ptr) + (count) > eom) { \
 149                         __set_h_errno (NO_RECOVERY); \
 150                         return (NULL); \
 151                 } \
 152         } while (0)
 153
 154
 155 static struct hostent *
 156 getanswer (const querybuf *answer, int anslen, const char *qname, int qtype)
 157 {
 158         const HEADER *hp;
 159         const u_char *cp;
 160         int n;
 161         const u_char *eom, *erdata;
 162         char *bp, **ap, **hap;
 163         int type, class, buflen, ancount, qdcount;
 164         int haveanswer, had_error;
 165         int toobig = 0;
 166         char tbuf[MAXDNAME];
 167         const char *tname;
 168         int (*name_ok) (const char *);
 169
 170         tname = qname;
 171         host.h_name = NULL;
 172         eom = answer->buf + anslen;
 173         switch (qtype) {
 174         case T_A:
 175         case T_AAAA:
 176                 name_ok = res_hnok;
 177                 break;
 178         case T_PTR:
 179                 name_ok = res_dnok;
 180                 break;
 181         default:
 182                 return (NULL);  /* XXX should be abort(); */
 183         }
 184         /*
 185          * find first satisfactory answer
 186          */
 187         hp = &answer->hdr;
 188         ancount = ntohs(hp->ancount);
 189         qdcount = ntohs(hp->qdcount);
 190         bp = hostbuf;
 191         buflen = sizeof hostbuf;
 192         cp = answer->buf;
 193         BOUNDED_INCR(HFIXEDSZ);
 194         if (qdcount != 1) {
 195                 __set_h_errno (NO_RECOVERY);
 196                 return (NULL);
 197         }
 198         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 199         if ((n < 0) || !(*name_ok)(bp)) {
 200                 __set_h_errno (NO_RECOVERY);
 201                 return (NULL);
 202         }
 203         BOUNDED_INCR(n + QFIXEDSZ);
 204         if (qtype == T_A || qtype == T_AAAA) {
 205                 /* res_send() has already verified that the query name is the
 206                  * same as the one we sent; this just gets the expanded name
 207                  * (i.e., with the succeeding search-domain tacked on).
 208                  */
 209                 n = strlen(bp) + 1;             /* for the \0 */
 210                 if (n >= MAXHOSTNAMELEN) {
 211                         __set_h_errno (NO_RECOVERY);
 212                         return (NULL);
 213                 }
 214                 host.h_name = bp;
 215                 bp += n;
 216                 buflen -= n;
 217                 /* The qname can be abbreviated, but h_name is now absolute. */
 218                 qname = host.h_name;
 219         }
 220         ap = host_aliases;
 221         *ap = NULL;
 222         host.h_aliases = host_aliases;
 223         hap = h_addr_ptrs;
 224         *hap = NULL;
 225         host.h_addr_list = h_addr_ptrs;
 226         haveanswer = 0;
 227         had_error = 0;
 228         while (ancount-- > 0 && cp < eom && !had_error) {
 229                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 230                 if ((n < 0) || !(*name_ok)(bp)) {
 231                         had_error++;
 232                         continue;
 233                 }
 234                 cp += n;                        /* name */
 235                 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
 236                 type = ns_get16(cp);
 237                 cp += INT16SZ;                  /* type */
 238                 class = ns_get16(cp);
 239                 cp += INT16SZ + INT32SZ;        /* class, TTL */
 240                 n = ns_get16(cp);
 241                 cp += INT16SZ;                  /* len */
 242                 BOUNDS_CHECK(cp, n);
 243                 erdata = cp + n;
 244                 if (class != C_IN) {
 245                         /* XXX - debug? syslog? */
 246                         cp += n;
 247                         continue;               /* XXX - had_error++ ? */
 248                 }
 249                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 250                         if (ap >= &host_aliases[MAXALIASES-1])
 251                                 continue;
 252                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 253                         if ((n < 0) || !(*name_ok)(tbuf)) {
 254                                 had_error++;
 255                                 continue;
 256                         }
 257                         cp += n;
 258                         if (cp != erdata) {
 259                                 __set_h_errno (NO_RECOVERY);
 260                                 return (NULL);
 261                         }
 262                         /* Store alias. */
 263                         *ap++ = bp;
 264                         n = strlen(bp) + 1;     /* for the \0 */
 265                         if (n >= MAXHOSTNAMELEN) {
 266                                 had_error++;
 267                                 continue;
 268                         }
 269                         bp += n;
 270                         buflen -= n;
 271                         /* Get canonical name. */
 272                         n = strlen(tbuf) + 1;   /* for the \0 */
 273                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 274                                 had_error++;
 275                                 continue;
 276                         }
 277                         strcpy(bp, tbuf);
 278                         host.h_name = bp;
 279                         bp += n;
 280                         buflen -= n;
 281                         continue;
 282                 }
 283                 if (qtype == T_PTR && type == T_CNAME) {
 284                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 285                         if (n < 0 || !res_dnok(tbuf)) {
 286                                 had_error++;
 287                                 continue;
 288                         }
 289                         cp += n;
 290                         if (cp != erdata) {
 291                                 __set_h_errno (NO_RECOVERY);
 292                                 return (NULL);
 293                         }
 294                         /* Get canonical name. */
 295                         n = strlen(tbuf) + 1;   /* for the \0 */
 296                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 297                                 had_error++;
 298                                 continue;
 299                         }
 300                         strcpy(bp, tbuf);
 301                         tname = bp;
 302                         bp += n;
 303                         buflen -= n;
 304                         continue;
 305                 }
 306                 if (type != qtype) {
 307                         /* Log a low priority message if we get an unexpected
 308                          * record, but skip it if we are using DNSSEC since it
 309                          * uses many different types in responses that do not
 310                          * match QTYPE.
 311                          */
 312                         cp += n;
 313                         continue;               /* XXX - had_error++ ? */
 314                 }
 315                 switch (type) {
 316                 case T_PTR:
 317                         if (strcasecmp(tname, bp) != 0) {
 318                                 cp += n;
 319                                 continue;       /* XXX - had_error++ ? */
 320                         }
 321                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 322                         if ((n < 0) || !res_hnok(bp)) {
 323                                 had_error++;
 324                                 break;
 325                         }
 326                         cp += n;
 327                         if (cp != erdata) {
 328                                 __set_h_errno (NO_RECOVERY);
 329                                 return (NULL);
 330                         }
 331                         if (!haveanswer)
 332                                 host.h_name = bp;
 333                         else if (ap < &host_aliases[MAXALIASES-1])
 334                                 *ap++ = bp;
 335                         else
 336                                 n = -1;
 337                         if (n != -1) {
 338                                 n = strlen(bp) + 1;     /* for the \0 */
 339                                 if (n >= MAXHOSTNAMELEN) {
 340                                         had_error++;
 341                                         break;
 342                                 }
 343                                 bp += n;
 344                                 buflen -= n;
 345                         }
 346                         break;
 347                 case T_A:
 348                 case T_AAAA:
 349                         if (strcasecmp(host.h_name, bp) != 0) {
 350                                 cp += n;
 351                                 continue;       /* XXX - had_error++ ? */
 352                         }
 353                         if (n != host.h_length) {
 354                                 cp += n;
 355                                 continue;
 356                         }
 357                         if (!haveanswer) {
 358                                 int nn;
 359
 360                                 host.h_name = bp;
 361                                 nn = strlen(bp) + 1;    /* for the \0 */
 362                                 bp += nn;
 363                                 buflen -= nn;
 364                         }
 365
 366                         /* XXX: when incrementing bp, we have to decrement
 367                          * buflen by the same amount --okir */
 368                         buflen -= sizeof(align) - ((u_long)bp % sizeof(align));
 369
 370                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 371
 372                         if (bp + n >= &hostbuf[sizeof hostbuf]) {
 373                                 Dprintf("size (%d) too big\n", n);
 374                                 had_error++;
 375                                 continue;
 376                         }
 377                         if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
 378                                 if (!toobig++) {
 379                                         Dprintf("Too many addresses (%d)\n",
 380                                                 MAXADDRS);
 381                                 }
 382                                 cp += n;
 383                                 continue;
 384                         }
 385                         memmove(*hap++ = bp, cp, n);
 386                         bp += n;
 387                         buflen -= n;
 388                         cp += n;
 389                         if (cp != erdata) {
 390                                 __set_h_errno (NO_RECOVERY);
 391                                 return (NULL);
 392                         }
 393                         break;
 394                 default:
 395                         abort();
 396                 }
 397                 if (!had_error)
 398                         haveanswer++;
 399         }
 400         if (haveanswer) {
 401                 *ap = NULL;
 402                 *hap = NULL;
 403                 /*
 404                  * Note: we sort even if host can take only one address
 405                  * in its return structures - should give it the "best"
 406                  * address in that case, not some random one
 407                  */
 408                 if (_res.nsort && haveanswer > 1 && qtype == T_A)
 409                         addrsort(h_addr_ptrs, haveanswer);
 410                 if (!host.h_name) {
 411                         n = strlen(qname) + 1;  /* for the \0 */
 412                         if (n > buflen || n >= MAXHOSTNAMELEN)
 413                                 goto no_recovery;
 414                         strcpy(bp, qname);
 415                         host.h_name = bp;
 416                         bp += n;
 417                         buflen -= n;
 418                 }
 419                 if (res_use_inet6 ())
 420                         map_v4v6_hostent(&host, &bp, &buflen);
 421                 __set_h_errno (NETDB_SUCCESS);
 422                 return (&host);
 423         }
 424  no_recovery:
 425         __set_h_errno (NO_RECOVERY);
 426         return (NULL);
 427 }
 428
 429 extern struct hostent *res_gethostbyname2(const char *name, int af);
 430 libresolv_hidden_proto (res_gethostbyname2)
 431
 432 struct hostent *
 433 res_gethostbyname (const char *name)
 434 {
 435   struct resolv_context *ctx = __resolv_context_get ();
 436   if (ctx == NULL)
 437     {
 438       __set_h_errno (NETDB_INTERNAL);
 439       return NULL;
 440     }
 441
 442   if (res_use_inet6 ())
 443     {
 444       struct hostent *hp = res_gethostbyname2_context (ctx, name, AF_INET6);
 445       if (hp != NULL)
 446         {
 447           __resolv_context_put (ctx);
 448           return hp;
 449         }
 450     }
 451   struct hostent *hp = res_gethostbyname2_context (ctx, name, AF_INET);
 452   __resolv_context_put (ctx);
 453   return hp;
 454 }
 455 compat_symbol (libresolv, res_gethostbyname, res_gethostbyname, GLIBC_2_0);
 456
 457 static struct hostent *
 458 res_gethostbyname2_context (struct resolv_context *ctx,
 459                             const char *name, int af)
 460 {
 461         union
 462         {
 463           querybuf *buf;
 464           u_char *ptr;
 465         } buf;
 466         querybuf *origbuf;
 467         const char *cp;
 468         char *bp;
 469         int n, size, type, len;
 470         struct hostent *ret;
 471
 472         switch (af) {
 473         case AF_INET:
 474                 size = INADDRSZ;
 475                 type = T_A;
 476                 break;
 477         case AF_INET6:
 478                 size = IN6ADDRSZ;
 479                 type = T_AAAA;
 480                 break;
 481         default:
 482                 __set_h_errno (NETDB_INTERNAL);
 483                 __set_errno (EAFNOSUPPORT);
 484                 return (NULL);
 485         }
 486
 487         host.h_addrtype = af;
 488         host.h_length = size;
 489
 490         /*
 491          * if there aren't any dots, it could be a user-level alias.
 492          * this is also done in res_query() since we are not the only
 493          * function that looks up host names.
 494          */
 495         char abuf[MAXDNAME];
 496         if (strchr (name, '.') != NULL
 497             && (cp = __res_context_hostalias (ctx, name, abuf, sizeof (abuf))))
 498           name = cp;
 499
 500         /*
 501          * disallow names consisting only of digits/dots, unless
 502          * they end in a dot.
 503          */
 504         if (isdigit(name[0]))
 505                 for (cp = name;; ++cp) {
 506                         if (!*cp) {
 507                                 if (*--cp == '.')
 508                                         break;
 509                                 /*
 510                                  * All-numeric, no dot at the end.
 511                                  * Fake up a hostent as if we'd actually
 512                                  * done a lookup.
 513                                  */
 514                                 if (inet_pton(af, name, host_addr) <= 0) {
 515                                         __set_h_errno (HOST_NOT_FOUND);
 516                                         return (NULL);
 517                                 }
 518                                 strncpy(hostbuf, name, MAXDNAME);
 519                                 hostbuf[MAXDNAME] = '\0';
 520                                 bp = hostbuf + MAXDNAME;
 521                                 len = sizeof hostbuf - MAXDNAME;
 522                                 host.h_name = hostbuf;
 523                                 host.h_aliases = host_aliases;
 524                                 host_aliases[0] = NULL;
 525                                 h_addr_ptrs[0] = (char *)host_addr;
 526                                 h_addr_ptrs[1] = NULL;
 527                                 host.h_addr_list = h_addr_ptrs;
 528                                 if (res_use_inet6 ())
 529                                         map_v4v6_hostent(&host, &bp, &len);
 530                                 __set_h_errno (NETDB_SUCCESS);
 531                                 return (&host);
 532                         }
 533                         if (!isdigit(*cp) && *cp != '.')
 534                                 break;
 535                }
 536         if ((isxdigit(name[0]) && strchr(name, ':') != NULL) ||
 537             name[0] == ':')
 538                 for (cp = name;; ++cp) {
 539                         if (!*cp) {
 540                                 if (*--cp == '.')
 541                                         break;
 542                                 /*
 543                                  * All-IPv6-legal, no dot at the end.
 544                                  * Fake up a hostent as if we'd actually
 545                                  * done a lookup.
 546                                  */
 547                                 if (inet_pton(af, name, host_addr) <= 0) {
 548                                         __set_h_errno (HOST_NOT_FOUND);
 549                                         return (NULL);
 550                                 }
 551                                 strncpy(hostbuf, name, MAXDNAME);
 552                                 hostbuf[MAXDNAME] = '\0';
 553                                 bp = hostbuf + MAXDNAME;
 554                                 len = sizeof hostbuf - MAXDNAME;
 555                                 host.h_name = hostbuf;
 556                                 host.h_aliases = host_aliases;
 557                                 host_aliases[0] = NULL;
 558                                 h_addr_ptrs[0] = (char *)host_addr;
 559                                 h_addr_ptrs[1] = NULL;
 560                                 host.h_addr_list = h_addr_ptrs;
 561                                 __set_h_errno (NETDB_SUCCESS);
 562                                 return (&host);
 563                         }
 564                         if (!isxdigit(*cp) && *cp != ':' && *cp != '.')
 565                                 break;
 566                 }
 567
 568         buf.buf = origbuf = (querybuf *) alloca (1024);
 569
 570         if ((n = __res_context_search
 571              (ctx, name, C_IN, type, buf.buf->buf, 1024,
 572               &buf.ptr, NULL, NULL, NULL, NULL)) < 0) {
 573                 if (buf.buf != origbuf)
 574                         free (buf.buf);
 575                 Dprintf("res_nsearch failed (%d)\n", n);
 576                 if (errno == ECONNREFUSED)
 577                         return (_gethtbyname2(name, af));
 578                 return (NULL);
 579         }
 580         ret = getanswer(buf.buf, n, name, type);
 581         if (buf.buf != origbuf)
 582                 free (buf.buf);
 583         return ret;
 584 }
 585
 586 struct hostent *
 587 res_gethostbyname2 (const char *name, int af)
 588 {
 589   struct resolv_context *ctx = __resolv_context_get ();
 590   if (ctx == NULL)
 591     {
 592       __set_h_errno (NETDB_INTERNAL);
 593       return NULL;
 594     }
 595   struct hostent *hp = res_gethostbyname2_context (ctx, name, AF_INET);
 596   __resolv_context_put (ctx);
 597   return hp;
 598 }
 599 libresolv_hidden_def (res_gethostbyname2)
 600 compat_symbol (libresolv, res_gethostbyname2, res_gethostbyname2, GLIBC_2_0);
 601
 602 static struct hostent *
 603 res_gethostbyaddr_context (struct resolv_context *ctx,
 604                            const void *addr, socklen_t len, int af)
 605 {
 606         const u_char *uaddr = (const u_char *)addr;
 607         static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
 608         static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
 609         int n;
 610         socklen_t size;
 611         union
 612         {
 613           querybuf *buf;
 614           u_char *ptr;
 615         } buf;
 616         querybuf *orig_buf;
 617         struct hostent *hp;
 618         char qbuf[MAXDNAME+1], *qp = NULL;
 619
 620         if (af == AF_INET6 && len == IN6ADDRSZ &&
 621             (!memcmp(uaddr, mapped, sizeof mapped) ||
 622              !memcmp(uaddr, tunnelled, sizeof tunnelled))) {
 623                 /* Unmap. */
 624                 addr += sizeof mapped;
 625                 uaddr += sizeof mapped;
 626                 af = AF_INET;
 627                 len = INADDRSZ;
 628         }
 629         switch (af) {
 630         case AF_INET:
 631                 size = INADDRSZ;
 632                 break;
 633         case AF_INET6:
 634                 size = IN6ADDRSZ;
 635                 break;
 636         default:
 637                 __set_errno (EAFNOSUPPORT);
 638                 __set_h_errno (NETDB_INTERNAL);
 639                 return (NULL);
 640         }
 641         if (size != len) {
 642                 __set_errno (EINVAL);
 643                 __set_h_errno (NETDB_INTERNAL);
 644                 return (NULL);
 645         }
 646         switch (af) {
 647         case AF_INET:
 648                 (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 649                                (uaddr[3] & 0xff),
 650                                (uaddr[2] & 0xff),
 651                                (uaddr[1] & 0xff),
 652                                (uaddr[0] & 0xff));
 653                 break;
 654         case AF_INET6:
 655                 qp = qbuf;
 656                 for (n = IN6ADDRSZ - 1; n >= 0; n--) {
 657                         qp += sprintf(qp, "%x.%x.",
 658                                       uaddr[n] & 0xf,
 659                                       (uaddr[n] >> 4) & 0xf);
 660                 }
 661                 strcpy(qp, "ip6.arpa");
 662                 break;
 663         default:
 664                 abort();
 665         }
 666
 667         buf.buf = orig_buf = (querybuf *) alloca (1024);
 668
 669         n = __res_context_query (ctx, qbuf, C_IN, T_PTR, buf.buf->buf, 1024,
 670                                  &buf.ptr, NULL, NULL, NULL, NULL);
 671         if (n < 0) {
 672                 if (buf.buf != orig_buf)
 673                         free (buf.buf);
 674                 Dprintf("res_nquery failed (%d)\n", n);
 675                 if (errno == ECONNREFUSED)
 676                         return (_gethtbyaddr(addr, len, af));
 677                 return (NULL);
 678         }
 679         hp = getanswer(buf.buf, n, qbuf, T_PTR);
 680         if (buf.buf != orig_buf)
 681                 free (buf.buf);
 682         if (!hp)
 683                 return (NULL);  /* h_errno was set by getanswer() */
 684         hp->h_addrtype = af;
 685         hp->h_length = len;
 686         memmove(host_addr, addr, len);
 687         h_addr_ptrs[0] = (char *)host_addr;
 688         h_addr_ptrs[1] = NULL;
 689         if (af == AF_INET && res_use_inet6 ()) {
 690                 map_v4v6_address((char*)host_addr, (char*)host_addr);
 691                 hp->h_addrtype = AF_INET6;
 692                 hp->h_length = IN6ADDRSZ;
 693         }
 694         __set_h_errno (NETDB_SUCCESS);
 695         return (hp);
 696 }
 697
 698 struct hostent *
 699 res_gethostbyaddr (const void *addr, socklen_t len, int af)
 700 {
 701   struct resolv_context *ctx = __resolv_context_get ();
 702   if (ctx == NULL)
 703     {
 704       __set_h_errno (NETDB_INTERNAL);
 705       return NULL;
 706     }
 707   struct hostent *hp = res_gethostbyaddr_context (ctx, addr, len, af);
 708   __resolv_context_put (ctx);
 709   return hp;
 710 }
 711 compat_symbol (libresolv, res_gethostbyaddr, res_gethostbyaddr, GLIBC_2_0);
 712
 713 void
 714 _sethtent (int f)
 715 {
 716         if (!hostf)
 717                 hostf = fopen(_PATH_HOSTS, "rce" );
 718         else
 719                 rewind(hostf);
 720         stayopen = f;
 721 }
 722 libresolv_hidden_def (_sethtent)
 723 compat_symbol (libresolv, _sethtent, _sethtent, GLIBC_2_0);
 724
 725 static void
 726 _endhtent (void)
 727 {
 728         if (hostf && !stayopen) {
 729                 (void) fclose(hostf);
 730                 hostf = NULL;
 731         }
 732 }
 733
 734 struct hostent *
 735 _gethtent (void)
 736 {
 737         char *p;
 738         char *cp, **q;
 739         int af, len;
 740
 741         if (!hostf && !(hostf = fopen(_PATH_HOSTS, "rce" ))) {
 742                 __set_h_errno (NETDB_INTERNAL);
 743                 return (NULL);
 744         }
 745  again:
 746         if (!(p = fgets(hostbuf, sizeof hostbuf, hostf))) {
 747                 __set_h_errno (HOST_NOT_FOUND);
 748                 return (NULL);
 749         }
 750         if (*p == '#')
 751                 goto again;
 752         if (!(cp = strpbrk(p, "#\n")))
 753                 goto again;
 754         *cp = '\0';
 755         if (!(cp = strpbrk(p, " \t")))
 756                 goto again;
 757         *cp++ = '\0';
 758         if (inet_pton(AF_INET6, p, host_addr) > 0) {
 759                 af = AF_INET6;
 760                 len = IN6ADDRSZ;
 761         } else if (inet_pton(AF_INET, p, host_addr) > 0) {
 762                 if (res_use_inet6 ()) {
 763                         map_v4v6_address((char*)host_addr, (char*)host_addr);
 764                         af = AF_INET6;
 765                         len = IN6ADDRSZ;
 766                 } else {
 767                         af = AF_INET;
 768                         len = INADDRSZ;
 769                 }
 770         } else {
 771                 goto again;
 772         }
 773         h_addr_ptrs[0] = (char *)host_addr;
 774         h_addr_ptrs[1] = NULL;
 775         host.h_addr_list = h_addr_ptrs;
 776         host.h_length = len;
 777         host.h_addrtype = af;
 778         while (*cp == ' ' || *cp == '\t')
 779                 cp++;
 780         host.h_name = cp;
 781         q = host.h_aliases = host_aliases;
 782         if ((cp = strpbrk(cp, " \t")))
 783                 *cp++ = '\0';
 784         while (cp && *cp) {
 785                 if (*cp == ' ' || *cp == '\t') {
 786                         cp++;
 787                         continue;
 788                 }
 789                 if (q < &host_aliases[MAXALIASES - 1])
 790                         *q++ = cp;
 791                 if ((cp = strpbrk(cp, " \t")))
 792                         *cp++ = '\0';
 793         }
 794         *q = NULL;
 795         __set_h_errno (NETDB_SUCCESS);
 796         return (&host);
 797 }
 798 libresolv_hidden_def (_gethtent)
 799 compat_symbol (libresolv, _gethtent, _gethtent, GLIBC_2_0);
 800
 801 struct hostent *
 802 _gethtbyname (const char *name)
 803 {
 804         struct hostent *hp;
 805
 806         if (res_use_inet6 ()) {
 807                 hp = _gethtbyname2(name, AF_INET6);
 808                 if (hp)
 809                         return (hp);
 810         }
 811         return (_gethtbyname2(name, AF_INET));
 812 }
 813 compat_symbol (libresolv, _gethtbyname, _gethtbyname, GLIBC_2_0);
 814
 815 struct hostent *
 816 _gethtbyname2 (const char *name, int af)
 817 {
 818         struct hostent *p;
 819         char **cp;
 820
 821         _sethtent(0);
 822         while ((p = _gethtent())) {
 823                 if (p->h_addrtype != af)
 824                         continue;
 825                 if (strcasecmp(p->h_name, name) == 0)
 826                         break;
 827                 for (cp = p->h_aliases; *cp != 0; cp++)
 828                         if (strcasecmp(*cp, name) == 0)
 829                                 goto found;
 830         }
 831  found:
 832         _endhtent();
 833         return (p);
 834 }
 835 libresolv_hidden_def (_gethtbyname2)
 836 compat_symbol (libresolv, _gethtbyname2, _gethtbyname2, GLIBC_2_0);
 837
 838 struct hostent *
 839 _gethtbyaddr (const char *addr, size_t len, int af)
 840 {
 841         struct hostent *p;
 842
 843         _sethtent(0);
 844         while ((p = _gethtent()))
 845                 if (p->h_addrtype == af && !memcmp(p->h_addr, addr, len))
 846                         break;
 847         _endhtent();
 848         return (p);
 849 }
 850 libresolv_hidden_def (_gethtbyaddr)
 851 compat_symbol (libresolv, _gethtbyaddr, _gethtbyaddr, GLIBC_2_0);
 852
 853 static void
 854 map_v4v6_address (const char *src, char *dst)
 855 {
 856         u_char *p = (u_char *)dst;
 857         char tmp[INADDRSZ];
 858         int i;
 859
 860         /* Stash a temporary copy so our caller can update in place. */
 861         memcpy(tmp, src, INADDRSZ);
 862         /* Mark this ipv6 addr as a mapped ipv4. */
 863         for (i = 0; i < 10; i++)
 864                 *p++ = 0x00;
 865         *p++ = 0xff;
 866         *p++ = 0xff;
 867         /* Retrieve the saved copy and we're done. */
 868         memcpy((void*)p, tmp, INADDRSZ);
 869 }
 870
 871 static void
 872 map_v4v6_hostent (struct hostent *hp, char **bpp, int *lenp)
 873 {
 874         char **ap;
 875
 876         if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
 877                 return;
 878         hp->h_addrtype = AF_INET6;
 879         hp->h_length = IN6ADDRSZ;
 880         for (ap = hp->h_addr_list; *ap; ap++) {
 881                 int i = sizeof(align) - ((u_long)*bpp % sizeof(align));
 882
 883                 if (*lenp < (i + IN6ADDRSZ)) {
 884                         /* Out of memory.  Truncate address list here.  XXX */
 885                         *ap = NULL;
 886                         return;
 887                 }
 888                 *bpp += i;
 889                 *lenp -= i;
 890                 map_v4v6_address(*ap, *bpp);
 891                 *ap = *bpp;
 892                 *bpp += IN6ADDRSZ;
 893                 *lenp -= IN6ADDRSZ;
 894         }
 895 }
 896
 897 extern void
 898 addrsort (char **ap, int num)
 899 {
 900         int i, j;
 901         char **p;
 902         short aval[MAXADDRS];
 903         int needsort = 0;
 904
 905         p = ap;
 906         for (i = 0; i < num; i++, p++) {
 907             for (j = 0 ; (unsigned)j < _res.nsort; j++)
 908                 if (_res.sort_list[j].addr.s_addr ==
 909                     (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 910                         break;
 911             aval[i] = j;
 912             if (needsort == 0 && i > 0 && j < aval[i-1])
 913                 needsort = i;
 914         }
 915         if (!needsort)
 916             return;
 917
 918         while (needsort < num) {
 919             for (j = needsort - 1; j >= 0; j--) {
 920                 if (aval[j] > aval[j+1]) {
 921                     char *hp;
 922
 923                     i = aval[j];
 924                     aval[j] = aval[j+1];
 925                     aval[j+1] = i;
 926
 927                     hp = ap[j];
 928                     ap[j] = ap[j+1];
 929                     ap[j+1] = hp;
 930
 931                 } else
 932                     break;
 933             }
 934             needsort++;
 935         }
 936 }
 937
 938 #endif  /* SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_25) */