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 # define BOUNDED_INCR(x) \
 123         do { \
 124                 cp += x; \
 125                 if (cp > eom) { \
 126                         __set_h_errno (NO_RECOVERY); \
 127                         return (NULL); \
 128                 } \
 129         } while (0)
 130
 131 # define BOUNDS_CHECK(ptr, count) \
 132         do { \
 133                 if ((ptr) + (count) > eom) { \
 134                         __set_h_errno (NO_RECOVERY); \
 135                         return (NULL); \
 136                 } \
 137         } while (0)
 138
 139
 140 static struct hostent *
 141 getanswer (const querybuf *answer, int anslen, const char *qname, int qtype)
 142 {
 143         const HEADER *hp;
 144         const u_char *cp;
 145         int n;
 146         const u_char *eom, *erdata;
 147         char *bp, **ap, **hap;
 148         int type, class, buflen, ancount, qdcount;
 149         int haveanswer, had_error;
 150         char tbuf[MAXDNAME];
 151         const char *tname;
 152         int (*name_ok) (const char *);
 153
 154         tname = qname;
 155         host.h_name = NULL;
 156         eom = answer->buf + anslen;
 157         switch (qtype) {
 158         case T_A:
 159         case T_AAAA:
 160                 name_ok = res_hnok;
 161                 break;
 162         case T_PTR:
 163                 name_ok = res_dnok;
 164                 break;
 165         default:
 166                 return (NULL);  /* XXX should be abort(); */
 167         }
 168         /*
 169          * find first satisfactory answer
 170          */
 171         hp = &answer->hdr;
 172         ancount = ntohs(hp->ancount);
 173         qdcount = ntohs(hp->qdcount);
 174         bp = hostbuf;
 175         buflen = sizeof hostbuf;
 176         cp = answer->buf;
 177         BOUNDED_INCR(HFIXEDSZ);
 178         if (qdcount != 1) {
 179                 __set_h_errno (NO_RECOVERY);
 180                 return (NULL);
 181         }
 182         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 183         if ((n < 0) || !(*name_ok)(bp)) {
 184                 __set_h_errno (NO_RECOVERY);
 185                 return (NULL);
 186         }
 187         BOUNDED_INCR(n + QFIXEDSZ);
 188         if (qtype == T_A || qtype == T_AAAA) {
 189                 /* res_send() has already verified that the query name is the
 190                  * same as the one we sent; this just gets the expanded name
 191                  * (i.e., with the succeeding search-domain tacked on).
 192                  */
 193                 n = strlen(bp) + 1;             /* for the \0 */
 194                 if (n >= MAXHOSTNAMELEN) {
 195                         __set_h_errno (NO_RECOVERY);
 196                         return (NULL);
 197                 }
 198                 host.h_name = bp;
 199                 bp += n;
 200                 buflen -= n;
 201                 /* The qname can be abbreviated, but h_name is now absolute. */
 202                 qname = host.h_name;
 203         }
 204         ap = host_aliases;
 205         *ap = NULL;
 206         host.h_aliases = host_aliases;
 207         hap = h_addr_ptrs;
 208         *hap = NULL;
 209         host.h_addr_list = h_addr_ptrs;
 210         haveanswer = 0;
 211         had_error = 0;
 212         while (ancount-- > 0 && cp < eom && !had_error) {
 213                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 214                 if ((n < 0) || !(*name_ok)(bp)) {
 215                         had_error++;
 216                         continue;
 217                 }
 218                 cp += n;                        /* name */
 219                 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
 220                 type = ns_get16(cp);
 221                 cp += INT16SZ;                  /* type */
 222                 class = ns_get16(cp);
 223                 cp += INT16SZ + INT32SZ;        /* class, TTL */
 224                 n = ns_get16(cp);
 225                 cp += INT16SZ;                  /* len */
 226                 BOUNDS_CHECK(cp, n);
 227                 erdata = cp + n;
 228                 if (class != C_IN) {
 229                         /* XXX - debug? syslog? */
 230                         cp += n;
 231                         continue;               /* XXX - had_error++ ? */
 232                 }
 233                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 234                         if (ap >= &host_aliases[MAXALIASES-1])
 235                                 continue;
 236                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 237                         if ((n < 0) || !(*name_ok)(tbuf)) {
 238                                 had_error++;
 239                                 continue;
 240                         }
 241                         cp += n;
 242                         if (cp != erdata) {
 243                                 __set_h_errno (NO_RECOVERY);
 244                                 return (NULL);
 245                         }
 246                         /* Store alias. */
 247                         *ap++ = bp;
 248                         n = strlen(bp) + 1;     /* for the \0 */
 249                         if (n >= MAXHOSTNAMELEN) {
 250                                 had_error++;
 251                                 continue;
 252                         }
 253                         bp += n;
 254                         buflen -= n;
 255                         /* Get canonical name. */
 256                         n = strlen(tbuf) + 1;   /* for the \0 */
 257                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 258                                 had_error++;
 259                                 continue;
 260                         }
 261                         strcpy(bp, tbuf);
 262                         host.h_name = bp;
 263                         bp += n;
 264                         buflen -= n;
 265                         continue;
 266                 }
 267                 if (qtype == T_PTR && type == T_CNAME) {
 268                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 269                         if (n < 0 || !res_dnok(tbuf)) {
 270                                 had_error++;
 271                                 continue;
 272                         }
 273                         cp += n;
 274                         if (cp != erdata) {
 275                                 __set_h_errno (NO_RECOVERY);
 276                                 return (NULL);
 277                         }
 278                         /* Get canonical name. */
 279                         n = strlen(tbuf) + 1;   /* for the \0 */
 280                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 281                                 had_error++;
 282                                 continue;
 283                         }
 284                         strcpy(bp, tbuf);
 285                         tname = bp;
 286                         bp += n;
 287                         buflen -= n;
 288                         continue;
 289                 }
 290                 if (type != qtype) {
 291                         /* Log a low priority message if we get an unexpected
 292                          * record, but skip it if we are using DNSSEC since it
 293                          * uses many different types in responses that do not
 294                          * match QTYPE.
 295                          */
 296                         cp += n;
 297                         continue;               /* XXX - had_error++ ? */
 298                 }
 299                 switch (type) {
 300                 case T_PTR:
 301                         if (strcasecmp(tname, bp) != 0) {
 302                                 cp += n;
 303                                 continue;       /* XXX - had_error++ ? */
 304                         }
 305                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 306                         if ((n < 0) || !res_hnok(bp)) {
 307                                 had_error++;
 308                                 break;
 309                         }
 310                         cp += n;
 311                         if (cp != erdata) {
 312                                 __set_h_errno (NO_RECOVERY);
 313                                 return (NULL);
 314                         }
 315                         if (!haveanswer)
 316                                 host.h_name = bp;
 317                         else if (ap < &host_aliases[MAXALIASES-1])
 318                                 *ap++ = bp;
 319                         else
 320                                 n = -1;
 321                         if (n != -1) {
 322                                 n = strlen(bp) + 1;     /* for the \0 */
 323                                 if (n >= MAXHOSTNAMELEN) {
 324                                         had_error++;
 325                                         break;
 326                                 }
 327                                 bp += n;
 328                                 buflen -= n;
 329                         }
 330                         break;
 331                 case T_A:
 332                 case T_AAAA:
 333                         if (strcasecmp(host.h_name, bp) != 0) {
 334                                 cp += n;
 335                                 continue;       /* XXX - had_error++ ? */
 336                         }
 337                         if (n != host.h_length) {
 338                                 cp += n;
 339                                 continue;
 340                         }
 341                         if (!haveanswer) {
 342                                 int nn;
 343
 344                                 host.h_name = bp;
 345                                 nn = strlen(bp) + 1;    /* for the \0 */
 346                                 bp += nn;
 347                                 buflen -= nn;
 348                         }
 349
 350                         /* XXX: when incrementing bp, we have to decrement
 351                          * buflen by the same amount --okir */
 352                         buflen -= sizeof(align) - ((u_long)bp % sizeof(align));
 353
 354                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 355
 356                         if (bp + n >= &hostbuf[sizeof hostbuf]) {
 357                                 had_error++;
 358                                 continue;
 359                         }
 360                         if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
 361                                 cp += n;
 362                                 continue;
 363                         }
 364                         memmove(*hap++ = bp, cp, n);
 365                         bp += n;
 366                         buflen -= n;
 367                         cp += n;
 368                         if (cp != erdata) {
 369                                 __set_h_errno (NO_RECOVERY);
 370                                 return (NULL);
 371                         }
 372                         break;
 373                 default:
 374                         abort();
 375                 }
 376                 if (!had_error)
 377                         haveanswer++;
 378         }
 379         if (haveanswer) {
 380                 *ap = NULL;
 381                 *hap = NULL;
 382                 /*
 383                  * Note: we sort even if host can take only one address
 384                  * in its return structures - should give it the "best"
 385                  * address in that case, not some random one
 386                  */
 387                 if (_res.nsort && haveanswer > 1 && qtype == T_A)
 388                         addrsort(h_addr_ptrs, haveanswer);
 389                 if (!host.h_name) {
 390                         n = strlen(qname) + 1;  /* for the \0 */
 391                         if (n > buflen || n >= MAXHOSTNAMELEN)
 392                                 goto no_recovery;
 393                         strcpy(bp, qname);
 394                         host.h_name = bp;
 395                         bp += n;
 396                         buflen -= n;
 397                 }
 398                 if (res_use_inet6 ())
 399                         map_v4v6_hostent(&host, &bp, &buflen);
 400                 __set_h_errno (NETDB_SUCCESS);
 401                 return (&host);
 402         }
 403  no_recovery:
 404         __set_h_errno (NO_RECOVERY);
 405         return (NULL);
 406 }
 407
 408 extern struct hostent *res_gethostbyname2(const char *name, int af);
 409 libresolv_hidden_proto (res_gethostbyname2)
 410
 411 struct hostent *
 412 res_gethostbyname (const char *name)
 413 {
 414   struct resolv_context *ctx = __resolv_context_get ();
 415   if (ctx == NULL)
 416     {
 417       __set_h_errno (NETDB_INTERNAL);
 418       return NULL;
 419     }
 420
 421   if (res_use_inet6 ())
 422     {
 423       struct hostent *hp = res_gethostbyname2_context (ctx, name, AF_INET6);
 424       if (hp != NULL)
 425         {
 426           __resolv_context_put (ctx);
 427           return hp;
 428         }
 429     }
 430   struct hostent *hp = res_gethostbyname2_context (ctx, name, AF_INET);
 431   __resolv_context_put (ctx);
 432   return hp;
 433 }
 434 compat_symbol (libresolv, res_gethostbyname, res_gethostbyname, GLIBC_2_0);
 435
 436 static struct hostent *
 437 res_gethostbyname2_context (struct resolv_context *ctx,
 438                             const char *name, int af)
 439 {
 440         union
 441         {
 442           querybuf *buf;
 443           u_char *ptr;
 444         } buf;
 445         querybuf *origbuf;
 446         const char *cp;
 447         char *bp;
 448         int n, size, type, len;
 449         struct hostent *ret;
 450
 451         switch (af) {
 452         case AF_INET:
 453                 size = INADDRSZ;
 454                 type = T_A;
 455                 break;
 456         case AF_INET6:
 457                 size = IN6ADDRSZ;
 458                 type = T_AAAA;
 459                 break;
 460         default:
 461                 __set_h_errno (NETDB_INTERNAL);
 462                 __set_errno (EAFNOSUPPORT);
 463                 return (NULL);
 464         }
 465
 466         host.h_addrtype = af;
 467         host.h_length = size;
 468
 469         /*
 470          * if there aren't any dots, it could be a user-level alias.
 471          * this is also done in res_query() since we are not the only
 472          * function that looks up host names.
 473          */
 474         char abuf[MAXDNAME];
 475         if (strchr (name, '.') != NULL
 476             && (cp = __res_context_hostalias (ctx, name, abuf, sizeof (abuf))))
 477           name = cp;
 478
 479         /*
 480          * disallow names consisting only of digits/dots, unless
 481          * they end in a dot.
 482          */
 483         if (isdigit(name[0]))
 484                 for (cp = name;; ++cp) {
 485                         if (!*cp) {
 486                                 if (*--cp == '.')
 487                                         break;
 488                                 /*
 489                                  * All-numeric, no dot at the end.
 490                                  * Fake up a hostent as if we'd actually
 491                                  * done a lookup.
 492                                  */
 493                                 if (inet_pton(af, name, host_addr) <= 0) {
 494                                         __set_h_errno (HOST_NOT_FOUND);
 495                                         return (NULL);
 496                                 }
 497                                 strncpy(hostbuf, name, MAXDNAME);
 498                                 hostbuf[MAXDNAME] = '\0';
 499                                 bp = hostbuf + MAXDNAME;
 500                                 len = sizeof hostbuf - MAXDNAME;
 501                                 host.h_name = hostbuf;
 502                                 host.h_aliases = host_aliases;
 503                                 host_aliases[0] = NULL;
 504                                 h_addr_ptrs[0] = (char *)host_addr;
 505                                 h_addr_ptrs[1] = NULL;
 506                                 host.h_addr_list = h_addr_ptrs;
 507                                 if (res_use_inet6 ())
 508                                         map_v4v6_hostent(&host, &bp, &len);
 509                                 __set_h_errno (NETDB_SUCCESS);
 510                                 return (&host);
 511                         }
 512                         if (!isdigit(*cp) && *cp != '.')
 513                                 break;
 514                }
 515         if ((isxdigit(name[0]) && strchr(name, ':') != NULL) ||
 516             name[0] == ':')
 517                 for (cp = name;; ++cp) {
 518                         if (!*cp) {
 519                                 if (*--cp == '.')
 520                                         break;
 521                                 /*
 522                                  * All-IPv6-legal, no dot at the end.
 523                                  * Fake up a hostent as if we'd actually
 524                                  * done a lookup.
 525                                  */
 526                                 if (inet_pton(af, name, host_addr) <= 0) {
 527                                         __set_h_errno (HOST_NOT_FOUND);
 528                                         return (NULL);
 529                                 }
 530                                 strncpy(hostbuf, name, MAXDNAME);
 531                                 hostbuf[MAXDNAME] = '\0';
 532                                 bp = hostbuf + MAXDNAME;
 533                                 len = sizeof hostbuf - MAXDNAME;
 534                                 host.h_name = hostbuf;
 535                                 host.h_aliases = host_aliases;
 536                                 host_aliases[0] = NULL;
 537                                 h_addr_ptrs[0] = (char *)host_addr;
 538                                 h_addr_ptrs[1] = NULL;
 539                                 host.h_addr_list = h_addr_ptrs;
 540                                 __set_h_errno (NETDB_SUCCESS);
 541                                 return (&host);
 542                         }
 543                         if (!isxdigit(*cp) && *cp != ':' && *cp != '.')
 544                                 break;
 545                 }
 546
 547         buf.buf = origbuf = (querybuf *) alloca (1024);
 548
 549         if ((n = __res_context_search
 550              (ctx, name, C_IN, type, buf.buf->buf, 1024,
 551               &buf.ptr, NULL, NULL, NULL, NULL)) < 0) {
 552                 if (buf.buf != origbuf)
 553                         free (buf.buf);
 554                 if (errno == ECONNREFUSED)
 555                         return (_gethtbyname2(name, af));
 556                 return (NULL);
 557         }
 558         ret = getanswer(buf.buf, n, name, type);
 559         if (buf.buf != origbuf)
 560                 free (buf.buf);
 561         return ret;
 562 }
 563
 564 struct hostent *
 565 res_gethostbyname2 (const char *name, int af)
 566 {
 567   struct resolv_context *ctx = __resolv_context_get ();
 568   if (ctx == NULL)
 569     {
 570       __set_h_errno (NETDB_INTERNAL);
 571       return NULL;
 572     }
 573   struct hostent *hp = res_gethostbyname2_context (ctx, name, AF_INET);
 574   __resolv_context_put (ctx);
 575   return hp;
 576 }
 577 libresolv_hidden_def (res_gethostbyname2)
 578 compat_symbol (libresolv, res_gethostbyname2, res_gethostbyname2, GLIBC_2_0);
 579
 580 static struct hostent *
 581 res_gethostbyaddr_context (struct resolv_context *ctx,
 582                            const void *addr, socklen_t len, int af)
 583 {
 584         const u_char *uaddr = (const u_char *)addr;
 585         static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
 586         static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
 587         int n;
 588         socklen_t size;
 589         union
 590         {
 591           querybuf *buf;
 592           u_char *ptr;
 593         } buf;
 594         querybuf *orig_buf;
 595         struct hostent *hp;
 596         char qbuf[MAXDNAME+1], *qp = NULL;
 597
 598         if (af == AF_INET6 && len == IN6ADDRSZ &&
 599             (!memcmp(uaddr, mapped, sizeof mapped) ||
 600              !memcmp(uaddr, tunnelled, sizeof tunnelled))) {
 601                 /* Unmap. */
 602                 addr += sizeof mapped;
 603                 uaddr += sizeof mapped;
 604                 af = AF_INET;
 605                 len = INADDRSZ;
 606         }
 607         switch (af) {
 608         case AF_INET:
 609                 size = INADDRSZ;
 610                 break;
 611         case AF_INET6:
 612                 size = IN6ADDRSZ;
 613                 break;
 614         default:
 615                 __set_errno (EAFNOSUPPORT);
 616                 __set_h_errno (NETDB_INTERNAL);
 617                 return (NULL);
 618         }
 619         if (size != len) {
 620                 __set_errno (EINVAL);
 621                 __set_h_errno (NETDB_INTERNAL);
 622                 return (NULL);
 623         }
 624         switch (af) {
 625         case AF_INET:
 626                 (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 627                                (uaddr[3] & 0xff),
 628                                (uaddr[2] & 0xff),
 629                                (uaddr[1] & 0xff),
 630                                (uaddr[0] & 0xff));
 631                 break;
 632         case AF_INET6:
 633                 qp = qbuf;
 634                 for (n = IN6ADDRSZ - 1; n >= 0; n--) {
 635                         qp += sprintf(qp, "%x.%x.",
 636                                       uaddr[n] & 0xf,
 637                                       (uaddr[n] >> 4) & 0xf);
 638                 }
 639                 strcpy(qp, "ip6.arpa");
 640                 break;
 641         default:
 642                 abort();
 643         }
 644
 645         buf.buf = orig_buf = (querybuf *) alloca (1024);
 646
 647         n = __res_context_query (ctx, qbuf, C_IN, T_PTR, buf.buf->buf, 1024,
 648                                  &buf.ptr, NULL, NULL, NULL, NULL);
 649         if (n < 0) {
 650                 if (buf.buf != orig_buf)
 651                         free (buf.buf);
 652                 if (errno == ECONNREFUSED)
 653                         return (_gethtbyaddr(addr, len, af));
 654                 return (NULL);
 655         }
 656         hp = getanswer(buf.buf, n, qbuf, T_PTR);
 657         if (buf.buf != orig_buf)
 658                 free (buf.buf);
 659         if (!hp)
 660                 return (NULL);  /* h_errno was set by getanswer() */
 661         hp->h_addrtype = af;
 662         hp->h_length = len;
 663         memmove(host_addr, addr, len);
 664         h_addr_ptrs[0] = (char *)host_addr;
 665         h_addr_ptrs[1] = NULL;
 666         if (af == AF_INET && res_use_inet6 ()) {
 667                 map_v4v6_address((char*)host_addr, (char*)host_addr);
 668                 hp->h_addrtype = AF_INET6;
 669                 hp->h_length = IN6ADDRSZ;
 670         }
 671         __set_h_errno (NETDB_SUCCESS);
 672         return (hp);
 673 }
 674
 675 struct hostent *
 676 res_gethostbyaddr (const void *addr, socklen_t len, int af)
 677 {
 678   struct resolv_context *ctx = __resolv_context_get ();
 679   if (ctx == NULL)
 680     {
 681       __set_h_errno (NETDB_INTERNAL);
 682       return NULL;
 683     }
 684   struct hostent *hp = res_gethostbyaddr_context (ctx, addr, len, af);
 685   __resolv_context_put (ctx);
 686   return hp;
 687 }
 688 compat_symbol (libresolv, res_gethostbyaddr, res_gethostbyaddr, GLIBC_2_0);
 689
 690 void
 691 _sethtent (int f)
 692 {
 693         if (!hostf)
 694                 hostf = fopen(_PATH_HOSTS, "rce" );
 695         else
 696                 rewind(hostf);
 697         stayopen = f;
 698 }
 699 libresolv_hidden_def (_sethtent)
 700 compat_symbol (libresolv, _sethtent, _sethtent, GLIBC_2_0);
 701
 702 static void
 703 _endhtent (void)
 704 {
 705         if (hostf && !stayopen) {
 706                 (void) fclose(hostf);
 707                 hostf = NULL;
 708         }
 709 }
 710
 711 struct hostent *
 712 _gethtent (void)
 713 {
 714         char *p;
 715         char *cp, **q;
 716         int af, len;
 717
 718         if (!hostf && !(hostf = fopen(_PATH_HOSTS, "rce" ))) {
 719                 __set_h_errno (NETDB_INTERNAL);
 720                 return (NULL);
 721         }
 722  again:
 723         if (!(p = fgets(hostbuf, sizeof hostbuf, hostf))) {
 724                 __set_h_errno (HOST_NOT_FOUND);
 725                 return (NULL);
 726         }
 727         if (*p == '#')
 728                 goto again;
 729         if (!(cp = strpbrk(p, "#\n")))
 730                 goto again;
 731         *cp = '\0';
 732         if (!(cp = strpbrk(p, " \t")))
 733                 goto again;
 734         *cp++ = '\0';
 735         if (inet_pton(AF_INET6, p, host_addr) > 0) {
 736                 af = AF_INET6;
 737                 len = IN6ADDRSZ;
 738         } else if (inet_pton(AF_INET, p, host_addr) > 0) {
 739                 if (res_use_inet6 ()) {
 740                         map_v4v6_address((char*)host_addr, (char*)host_addr);
 741                         af = AF_INET6;
 742                         len = IN6ADDRSZ;
 743                 } else {
 744                         af = AF_INET;
 745                         len = INADDRSZ;
 746                 }
 747         } else {
 748                 goto again;
 749         }
 750         h_addr_ptrs[0] = (char *)host_addr;
 751         h_addr_ptrs[1] = NULL;
 752         host.h_addr_list = h_addr_ptrs;
 753         host.h_length = len;
 754         host.h_addrtype = af;
 755         while (*cp == ' ' || *cp == '\t')
 756                 cp++;
 757         host.h_name = cp;
 758         q = host.h_aliases = host_aliases;
 759         if ((cp = strpbrk(cp, " \t")))
 760                 *cp++ = '\0';
 761         while (cp && *cp) {
 762                 if (*cp == ' ' || *cp == '\t') {
 763                         cp++;
 764                         continue;
 765                 }
 766                 if (q < &host_aliases[MAXALIASES - 1])
 767                         *q++ = cp;
 768                 if ((cp = strpbrk(cp, " \t")))
 769                         *cp++ = '\0';
 770         }
 771         *q = NULL;
 772         __set_h_errno (NETDB_SUCCESS);
 773         return (&host);
 774 }
 775 libresolv_hidden_def (_gethtent)
 776 compat_symbol (libresolv, _gethtent, _gethtent, GLIBC_2_0);
 777
 778 struct hostent *
 779 _gethtbyname (const char *name)
 780 {
 781         struct hostent *hp;
 782
 783         if (res_use_inet6 ()) {
 784                 hp = _gethtbyname2(name, AF_INET6);
 785                 if (hp)
 786                         return (hp);
 787         }
 788         return (_gethtbyname2(name, AF_INET));
 789 }
 790 compat_symbol (libresolv, _gethtbyname, _gethtbyname, GLIBC_2_0);
 791
 792 struct hostent *
 793 _gethtbyname2 (const char *name, int af)
 794 {
 795         struct hostent *p;
 796         char **cp;
 797
 798         _sethtent(0);
 799         while ((p = _gethtent())) {
 800                 if (p->h_addrtype != af)
 801                         continue;
 802                 if (strcasecmp(p->h_name, name) == 0)
 803                         break;
 804                 for (cp = p->h_aliases; *cp != 0; cp++)
 805                         if (strcasecmp(*cp, name) == 0)
 806                                 goto found;
 807         }
 808  found:
 809         _endhtent();
 810         return (p);
 811 }
 812 libresolv_hidden_def (_gethtbyname2)
 813 compat_symbol (libresolv, _gethtbyname2, _gethtbyname2, GLIBC_2_0);
 814
 815 struct hostent *
 816 _gethtbyaddr (const char *addr, size_t len, int af)
 817 {
 818         struct hostent *p;
 819
 820         _sethtent(0);
 821         while ((p = _gethtent()))
 822                 if (p->h_addrtype == af && !memcmp(p->h_addr, addr, len))
 823                         break;
 824         _endhtent();
 825         return (p);
 826 }
 827 libresolv_hidden_def (_gethtbyaddr)
 828 compat_symbol (libresolv, _gethtbyaddr, _gethtbyaddr, GLIBC_2_0);
 829
 830 static void
 831 map_v4v6_address (const char *src, char *dst)
 832 {
 833         u_char *p = (u_char *)dst;
 834         char tmp[INADDRSZ];
 835         int i;
 836
 837         /* Stash a temporary copy so our caller can update in place. */
 838         memcpy(tmp, src, INADDRSZ);
 839         /* Mark this ipv6 addr as a mapped ipv4. */
 840         for (i = 0; i < 10; i++)
 841                 *p++ = 0x00;
 842         *p++ = 0xff;
 843         *p++ = 0xff;
 844         /* Retrieve the saved copy and we're done. */
 845         memcpy((void*)p, tmp, INADDRSZ);
 846 }
 847
 848 static void
 849 map_v4v6_hostent (struct hostent *hp, char **bpp, int *lenp)
 850 {
 851         char **ap;
 852
 853         if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
 854                 return;
 855         hp->h_addrtype = AF_INET6;
 856         hp->h_length = IN6ADDRSZ;
 857         for (ap = hp->h_addr_list; *ap; ap++) {
 858                 int i = sizeof(align) - ((u_long)*bpp % sizeof(align));
 859
 860                 if (*lenp < (i + IN6ADDRSZ)) {
 861                         /* Out of memory.  Truncate address list here.  XXX */
 862                         *ap = NULL;
 863                         return;
 864                 }
 865                 *bpp += i;
 866                 *lenp -= i;
 867                 map_v4v6_address(*ap, *bpp);
 868                 *ap = *bpp;
 869                 *bpp += IN6ADDRSZ;
 870                 *lenp -= IN6ADDRSZ;
 871         }
 872 }
 873
 874 extern void
 875 addrsort (char **ap, int num)
 876 {
 877         int i, j;
 878         char **p;
 879         short aval[MAXADDRS];
 880         int needsort = 0;
 881
 882         p = ap;
 883         for (i = 0; i < num; i++, p++) {
 884             for (j = 0 ; (unsigned)j < _res.nsort; j++)
 885                 if (_res.sort_list[j].addr.s_addr ==
 886                     (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 887                         break;
 888             aval[i] = j;
 889             if (needsort == 0 && i > 0 && j < aval[i-1])
 890                 needsort = i;
 891         }
 892         if (!needsort)
 893             return;
 894
 895         while (needsort < num) {
 896             for (j = needsort - 1; j >= 0; j--) {
 897                 if (aval[j] > aval[j+1]) {
 898                     char *hp;
 899
 900                     i = aval[j];
 901                     aval[j] = aval[j+1];
 902                     aval[j+1] = i;
 903
 904                     hp = ap[j];
 905                     ap[j] = ap[j+1];
 906                     ap[j+1] = hp;
 907
 908                 } else
 909                     break;
 910             }
 911             needsort++;
 912         }
 913 }
 914
 915 #endif  /* SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_25) */