resolv/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 <sys/types.h>
  58 #include <sys/param.h>
  59 #include <sys/socket.h>
  60 #include <netinet/in.h>
  61 #include <arpa/inet.h>
  62 #include <arpa/nameser.h>
  63
  64 #include <stdio.h>
  65 #include <netdb.h>
  66 #include <resolv.h>
  67 #include <ctype.h>
  68 #include <errno.h>
  69 #include <stdlib.h>
  70 #include <string.h>
  71
  72 #define MAXALIASES      35
  73 #define MAXADDRS        35
  74
  75 static char *h_addr_ptrs[MAXADDRS + 1];
  76
  77 static struct hostent host;
  78 static char *host_aliases[MAXALIASES];
  79 static char hostbuf[8*1024];
  80 static u_char host_addr[16];    /* IPv4 or IPv6 */
  81 static FILE *hostf = NULL;
  82 static int stayopen = 0;
  83
  84 static void map_v4v6_address (const char *src, char *dst) __THROW;
  85 static void map_v4v6_hostent (struct hostent *hp, char **bp, int *len) __THROW;
  86
  87 extern void addrsort (char **, int) __THROW;
  88
  89 #if PACKETSZ > 65536
  90 #define MAXPACKET       PACKETSZ
  91 #else
  92 #define MAXPACKET       65536
  93 #endif
  94
  95 /* As per RFC 1034 and 1035 a host name cannot exceed 255 octets in length.  */
  96 #ifdef MAXHOSTNAMELEN
  97 # undef MAXHOSTNAMELEN
  98 #endif
  99 #define MAXHOSTNAMELEN 256
 100
 101 typedef union {
 102     HEADER hdr;
 103     u_char buf[MAXPACKET];
 104 } querybuf;
 105
 106 typedef union {
 107     int32_t al;
 108     char ac;
 109 } align;
 110
 111 #ifndef h_errno
 112 extern int h_errno;
 113 #endif
 114
 115 #ifdef DEBUG
 116 static void
 117 Dprintf (char *msg, int num)
 118 {
 119         if (_res.options & RES_DEBUG) {
 120                 int save = errno;
 121
 122                 printf(msg, num);
 123                 __set_errno (save);
 124         }
 125 }
 126 #else
 127 # define Dprintf(msg, num) /*nada*/
 128 #endif
 129
 130 #define BOUNDED_INCR(x) \
 131         do { \
 132                 cp += x; \
 133                 if (cp > eom) { \
 134                         __set_h_errno (NO_RECOVERY); \
 135                         return (NULL); \
 136                 } \
 137         } while (0)
 138
 139 #define BOUNDS_CHECK(ptr, count) \
 140         do { \
 141                 if ((ptr) + (count) > eom) { \
 142                         __set_h_errno (NO_RECOVERY); \
 143                         return (NULL); \
 144                 } \
 145         } while (0)
 146
 147
 148 static struct hostent *
 149 getanswer (const querybuf *answer, int anslen, const char *qname, int qtype)
 150 {
 151         const HEADER *hp;
 152         const u_char *cp;
 153         int n;
 154         const u_char *eom, *erdata;
 155         char *bp, **ap, **hap;
 156         int type, class, buflen, ancount, qdcount;
 157         int haveanswer, had_error;
 158         int toobig = 0;
 159         char tbuf[MAXDNAME];
 160         const char *tname;
 161         int (*name_ok) (const char *);
 162
 163         tname = qname;
 164         host.h_name = NULL;
 165         eom = answer->buf + anslen;
 166         switch (qtype) {
 167         case T_A:
 168         case T_AAAA:
 169                 name_ok = res_hnok;
 170                 break;
 171         case T_PTR:
 172                 name_ok = res_dnok;
 173                 break;
 174         default:
 175                 return (NULL);  /* XXX should be abort(); */
 176         }
 177         /*
 178          * find first satisfactory answer
 179          */
 180         hp = &answer->hdr;
 181         ancount = ntohs(hp->ancount);
 182         qdcount = ntohs(hp->qdcount);
 183         bp = hostbuf;
 184         buflen = sizeof hostbuf;
 185         cp = answer->buf;
 186         BOUNDED_INCR(HFIXEDSZ);
 187         if (qdcount != 1) {
 188                 __set_h_errno (NO_RECOVERY);
 189                 return (NULL);
 190         }
 191         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 192         if ((n < 0) || !(*name_ok)(bp)) {
 193                 __set_h_errno (NO_RECOVERY);
 194                 return (NULL);
 195         }
 196         BOUNDED_INCR(n + QFIXEDSZ);
 197         if (qtype == T_A || qtype == T_AAAA) {
 198                 /* res_send() has already verified that the query name is the
 199                  * same as the one we sent; this just gets the expanded name
 200                  * (i.e., with the succeeding search-domain tacked on).
 201                  */
 202                 n = strlen(bp) + 1;             /* for the \0 */
 203                 if (n >= MAXHOSTNAMELEN) {
 204                         __set_h_errno (NO_RECOVERY);
 205                         return (NULL);
 206                 }
 207                 host.h_name = bp;
 208                 bp += n;
 209                 buflen -= n;
 210                 /* The qname can be abbreviated, but h_name is now absolute. */
 211                 qname = host.h_name;
 212         }
 213         ap = host_aliases;
 214         *ap = NULL;
 215         host.h_aliases = host_aliases;
 216         hap = h_addr_ptrs;
 217         *hap = NULL;
 218         host.h_addr_list = h_addr_ptrs;
 219         haveanswer = 0;
 220         had_error = 0;
 221         while (ancount-- > 0 && cp < eom && !had_error) {
 222                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 223                 if ((n < 0) || !(*name_ok)(bp)) {
 224                         had_error++;
 225                         continue;
 226                 }
 227                 cp += n;                        /* name */
 228                 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
 229                 type = ns_get16(cp);
 230                 cp += INT16SZ;                  /* type */
 231                 class = ns_get16(cp);
 232                 cp += INT16SZ + INT32SZ;        /* class, TTL */
 233                 n = ns_get16(cp);
 234                 cp += INT16SZ;                  /* len */
 235                 BOUNDS_CHECK(cp, n);
 236                 erdata = cp + n;
 237                 if (class != C_IN) {
 238                         /* XXX - debug? syslog? */
 239                         cp += n;
 240                         continue;               /* XXX - had_error++ ? */
 241                 }
 242                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 243                         if (ap >= &host_aliases[MAXALIASES-1])
 244                                 continue;
 245                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 246                         if ((n < 0) || !(*name_ok)(tbuf)) {
 247                                 had_error++;
 248                                 continue;
 249                         }
 250                         cp += n;
 251                         if (cp != erdata) {
 252                                 __set_h_errno (NO_RECOVERY);
 253                                 return (NULL);
 254                         }
 255                         /* Store alias. */
 256                         *ap++ = bp;
 257                         n = strlen(bp) + 1;     /* for the \0 */
 258                         if (n >= MAXHOSTNAMELEN) {
 259                                 had_error++;
 260                                 continue;
 261                         }
 262                         bp += n;
 263                         buflen -= n;
 264                         /* Get canonical name. */
 265                         n = strlen(tbuf) + 1;   /* for the \0 */
 266                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 267                                 had_error++;
 268                                 continue;
 269                         }
 270                         strcpy(bp, tbuf);
 271                         host.h_name = bp;
 272                         bp += n;
 273                         buflen -= n;
 274                         continue;
 275                 }
 276                 if (qtype == T_PTR && type == T_CNAME) {
 277                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 278                         if (n < 0 || !res_dnok(tbuf)) {
 279                                 had_error++;
 280                                 continue;
 281                         }
 282                         cp += n;
 283                         if (cp != erdata) {
 284                                 __set_h_errno (NO_RECOVERY);
 285                                 return (NULL);
 286                         }
 287                         /* Get canonical name. */
 288                         n = strlen(tbuf) + 1;   /* for the \0 */
 289                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 290                                 had_error++;
 291                                 continue;
 292                         }
 293                         strcpy(bp, tbuf);
 294                         tname = bp;
 295                         bp += n;
 296                         buflen -= n;
 297                         continue;
 298                 }
 299                 if (type != qtype) {
 300                         /* Log a low priority message if we get an unexpected
 301                          * record, but skip it if we are using DNSSEC since it
 302                          * uses many different types in responses that do not
 303                          * match QTYPE.
 304                          */
 305                         cp += n;
 306                         continue;               /* XXX - had_error++ ? */
 307                 }
 308                 switch (type) {
 309                 case T_PTR:
 310                         if (strcasecmp(tname, bp) != 0) {
 311                                 cp += n;
 312                                 continue;       /* XXX - had_error++ ? */
 313                         }
 314                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 315                         if ((n < 0) || !res_hnok(bp)) {
 316                                 had_error++;
 317                                 break;
 318                         }
 319                         cp += n;
 320                         if (cp != erdata) {
 321                                 __set_h_errno (NO_RECOVERY);
 322                                 return (NULL);
 323                         }
 324                         if (!haveanswer)
 325                                 host.h_name = bp;
 326                         else if (ap < &host_aliases[MAXALIASES-1])
 327                                 *ap++ = bp;
 328                         else
 329                                 n = -1;
 330                         if (n != -1) {
 331                                 n = strlen(bp) + 1;     /* for the \0 */
 332                                 if (n >= MAXHOSTNAMELEN) {
 333                                         had_error++;
 334                                         break;
 335                                 }
 336                                 bp += n;
 337                                 buflen -= n;
 338                         }
 339                         break;
 340                 case T_A:
 341                 case T_AAAA:
 342                         if (strcasecmp(host.h_name, bp) != 0) {
 343                                 cp += n;
 344                                 continue;       /* XXX - had_error++ ? */
 345                         }
 346                         if (n != host.h_length) {
 347                                 cp += n;
 348                                 continue;
 349                         }
 350                         if (!haveanswer) {
 351                                 int nn;
 352
 353                                 host.h_name = bp;
 354                                 nn = strlen(bp) + 1;    /* for the \0 */
 355                                 bp += nn;
 356                                 buflen -= nn;
 357                         }
 358
 359                         /* XXX: when incrementing bp, we have to decrement
 360                          * buflen by the same amount --okir */
 361                         buflen -= sizeof(align) - ((u_long)bp % sizeof(align));
 362
 363                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 364
 365                         if (bp + n >= &hostbuf[sizeof hostbuf]) {
 366                                 Dprintf("size (%d) too big\n", n);
 367                                 had_error++;
 368                                 continue;
 369                         }
 370                         if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
 371                                 if (!toobig++) {
 372                                         Dprintf("Too many addresses (%d)\n",
 373                                                 MAXADDRS);
 374                                 }
 375                                 cp += n;
 376                                 continue;
 377                         }
 378                         memmove(*hap++ = bp, cp, n);
 379                         bp += n;
 380                         buflen -= n;
 381                         cp += n;
 382                         if (cp != erdata) {
 383                                 __set_h_errno (NO_RECOVERY);
 384                                 return (NULL);
 385                         }
 386                         break;
 387                 default:
 388                         abort();
 389                 }
 390                 if (!had_error)
 391                         haveanswer++;
 392         }
 393         if (haveanswer) {
 394                 *ap = NULL;
 395                 *hap = NULL;
 396                 /*
 397                  * Note: we sort even if host can take only one address
 398                  * in its return structures - should give it the "best"
 399                  * address in that case, not some random one
 400                  */
 401                 if (_res.nsort && haveanswer > 1 && qtype == T_A)
 402                         addrsort(h_addr_ptrs, haveanswer);
 403                 if (!host.h_name) {
 404                         n = strlen(qname) + 1;  /* for the \0 */
 405                         if (n > buflen || n >= MAXHOSTNAMELEN)
 406                                 goto no_recovery;
 407                         strcpy(bp, qname);
 408                         host.h_name = bp;
 409                         bp += n;
 410                         buflen -= n;
 411                 }
 412                 if (_res.options & RES_USE_INET6)
 413                         map_v4v6_hostent(&host, &bp, &buflen);
 414                 __set_h_errno (NETDB_SUCCESS);
 415                 return (&host);
 416         }
 417  no_recovery:
 418         __set_h_errno (NO_RECOVERY);
 419         return (NULL);
 420 }
 421
 422 extern struct hostent *gethostbyname2(const char *name, int af);
 423 libresolv_hidden_proto (gethostbyname2)
 424
 425 struct hostent *
 426 gethostbyname (const char *name)
 427 {
 428         struct hostent *hp;
 429
 430         if (__res_maybe_init (&_res, 0) == -1) {
 431                 __set_h_errno (NETDB_INTERNAL);
 432                 return (NULL);
 433         }
 434         if (_res.options & RES_USE_INET6) {
 435                 hp = gethostbyname2(name, AF_INET6);
 436                 if (hp)
 437                         return (hp);
 438         }
 439         return (gethostbyname2(name, AF_INET));
 440 }
 441
 442 struct hostent *
 443 gethostbyname2 (const char *name, int af)
 444 {
 445         union
 446         {
 447           querybuf *buf;
 448           u_char *ptr;
 449         } buf;
 450         querybuf *origbuf;
 451         const char *cp;
 452         char *bp;
 453         int n, size, type, len;
 454         struct hostent *ret;
 455
 456         if (__res_maybe_init (&_res, 0) == -1) {
 457                 __set_h_errno (NETDB_INTERNAL);
 458                 return (NULL);
 459         }
 460
 461         switch (af) {
 462         case AF_INET:
 463                 size = INADDRSZ;
 464                 type = T_A;
 465                 break;
 466         case AF_INET6:
 467                 size = IN6ADDRSZ;
 468                 type = T_AAAA;
 469                 break;
 470         default:
 471                 __set_h_errno (NETDB_INTERNAL);
 472                 __set_errno (EAFNOSUPPORT);
 473                 return (NULL);
 474         }
 475
 476         host.h_addrtype = af;
 477         host.h_length = size;
 478
 479         /*
 480          * if there aren't any dots, it could be a user-level alias.
 481          * this is also done in res_query() since we are not the only
 482          * function that looks up host names.
 483          */
 484         if (!strchr(name, '.') && (cp = __hostalias(name)))
 485                 name = cp;
 486
 487         /*
 488          * disallow names consisting only of digits/dots, unless
 489          * they end in a dot.
 490          */
 491         if (isdigit(name[0]))
 492                 for (cp = name;; ++cp) {
 493                         if (!*cp) {
 494                                 if (*--cp == '.')
 495                                         break;
 496                                 /*
 497                                  * All-numeric, no dot at the end.
 498                                  * Fake up a hostent as if we'd actually
 499                                  * done a lookup.
 500                                  */
 501                                 if (inet_pton(af, name, host_addr) <= 0) {
 502                                         __set_h_errno (HOST_NOT_FOUND);
 503                                         return (NULL);
 504                                 }
 505                                 strncpy(hostbuf, name, MAXDNAME);
 506                                 hostbuf[MAXDNAME] = '\0';
 507                                 bp = hostbuf + MAXDNAME;
 508                                 len = sizeof hostbuf - MAXDNAME;
 509                                 host.h_name = hostbuf;
 510                                 host.h_aliases = host_aliases;
 511                                 host_aliases[0] = NULL;
 512                                 h_addr_ptrs[0] = (char *)host_addr;
 513                                 h_addr_ptrs[1] = NULL;
 514                                 host.h_addr_list = h_addr_ptrs;
 515                                 if (_res.options & RES_USE_INET6)
 516                                         map_v4v6_hostent(&host, &bp, &len);
 517                                 __set_h_errno (NETDB_SUCCESS);
 518                                 return (&host);
 519                         }
 520                         if (!isdigit(*cp) && *cp != '.')
 521                                 break;
 522                }
 523         if ((isxdigit(name[0]) && strchr(name, ':') != NULL) ||
 524             name[0] == ':')
 525                 for (cp = name;; ++cp) {
 526                         if (!*cp) {
 527                                 if (*--cp == '.')
 528                                         break;
 529                                 /*
 530                                  * All-IPv6-legal, no dot at the end.
 531                                  * Fake up a hostent as if we'd actually
 532                                  * done a lookup.
 533                                  */
 534                                 if (inet_pton(af, name, host_addr) <= 0) {
 535                                         __set_h_errno (HOST_NOT_FOUND);
 536                                         return (NULL);
 537                                 }
 538                                 strncpy(hostbuf, name, MAXDNAME);
 539                                 hostbuf[MAXDNAME] = '\0';
 540                                 bp = hostbuf + MAXDNAME;
 541                                 len = sizeof hostbuf - MAXDNAME;
 542                                 host.h_name = hostbuf;
 543                                 host.h_aliases = host_aliases;
 544                                 host_aliases[0] = NULL;
 545                                 h_addr_ptrs[0] = (char *)host_addr;
 546                                 h_addr_ptrs[1] = NULL;
 547                                 host.h_addr_list = h_addr_ptrs;
 548                                 __set_h_errno (NETDB_SUCCESS);
 549                                 return (&host);
 550                         }
 551                         if (!isxdigit(*cp) && *cp != ':' && *cp != '.')
 552                                 break;
 553                 }
 554
 555         buf.buf = origbuf = (querybuf *) alloca (1024);
 556
 557         if ((n = __libc_res_nsearch(&_res, name, C_IN, type, buf.buf->buf, 1024,
 558                                     &buf.ptr, NULL, NULL, NULL, NULL)) < 0) {
 559                 if (buf.buf != origbuf)
 560                         free (buf.buf);
 561                 Dprintf("res_nsearch failed (%d)\n", n);
 562                 if (errno == ECONNREFUSED)
 563                         return (_gethtbyname2(name, af));
 564                 return (NULL);
 565         }
 566         ret = getanswer(buf.buf, n, name, type);
 567         if (buf.buf != origbuf)
 568                 free (buf.buf);
 569         return ret;
 570 }
 571 libresolv_hidden_def (gethostbyname2)
 572
 573 struct hostent *
 574 gethostbyaddr (const void *addr, socklen_t len, int af)
 575 {
 576         const u_char *uaddr = (const u_char *)addr;
 577         static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
 578         static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
 579         int n;
 580         socklen_t size;
 581         union
 582         {
 583           querybuf *buf;
 584           u_char *ptr;
 585         } buf;
 586         querybuf *orig_buf;
 587         struct hostent *hp;
 588         char qbuf[MAXDNAME+1], *qp = NULL;
 589
 590         if (__res_maybe_init (&_res, 0) == -1) {
 591                 __set_h_errno (NETDB_INTERNAL);
 592                 return (NULL);
 593         }
 594         if (af == AF_INET6 && len == IN6ADDRSZ &&
 595             (!memcmp(uaddr, mapped, sizeof mapped) ||
 596              !memcmp(uaddr, tunnelled, sizeof tunnelled))) {
 597                 /* Unmap. */
 598                 addr += sizeof mapped;
 599                 uaddr += sizeof mapped;
 600                 af = AF_INET;
 601                 len = INADDRSZ;
 602         }
 603         switch (af) {
 604         case AF_INET:
 605                 size = INADDRSZ;
 606                 break;
 607         case AF_INET6:
 608                 size = IN6ADDRSZ;
 609                 break;
 610         default:
 611                 __set_errno (EAFNOSUPPORT);
 612                 __set_h_errno (NETDB_INTERNAL);
 613                 return (NULL);
 614         }
 615         if (size != len) {
 616                 __set_errno (EINVAL);
 617                 __set_h_errno (NETDB_INTERNAL);
 618                 return (NULL);
 619         }
 620         switch (af) {
 621         case AF_INET:
 622                 (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 623                                (uaddr[3] & 0xff),
 624                                (uaddr[2] & 0xff),
 625                                (uaddr[1] & 0xff),
 626                                (uaddr[0] & 0xff));
 627                 break;
 628         case AF_INET6:
 629                 qp = qbuf;
 630                 for (n = IN6ADDRSZ - 1; n >= 0; n--) {
 631                         qp += sprintf(qp, "%x.%x.",
 632                                       uaddr[n] & 0xf,
 633                                       (uaddr[n] >> 4) & 0xf);
 634                 }
 635                 strcpy(qp, "ip6.arpa");
 636                 break;
 637         default:
 638                 abort();
 639         }
 640
 641         buf.buf = orig_buf = (querybuf *) alloca (1024);
 642
 643         n = __libc_res_nquery(&_res, qbuf, C_IN, T_PTR, buf.buf->buf, 1024,
 644                               &buf.ptr, NULL, NULL, NULL, NULL);
 645         if (n < 0) {
 646                 if (buf.buf != orig_buf)
 647                         free (buf.buf);
 648                 Dprintf("res_nquery failed (%d)\n", n);
 649                 if (errno == ECONNREFUSED)
 650                         return (_gethtbyaddr(addr, len, af));
 651                 return (NULL);
 652         }
 653         hp = getanswer(buf.buf, n, qbuf, T_PTR);
 654         if (buf.buf != orig_buf)
 655                 free (buf.buf);
 656         if (!hp)
 657                 return (NULL);  /* h_errno was set by getanswer() */
 658         hp->h_addrtype = af;
 659         hp->h_length = len;
 660         memmove(host_addr, addr, len);
 661         h_addr_ptrs[0] = (char *)host_addr;
 662         h_addr_ptrs[1] = NULL;
 663         if (af == AF_INET && (_res.options & RES_USE_INET6)) {
 664                 map_v4v6_address((char*)host_addr, (char*)host_addr);
 665                 hp->h_addrtype = AF_INET6;
 666                 hp->h_length = IN6ADDRSZ;
 667         }
 668         __set_h_errno (NETDB_SUCCESS);
 669         return (hp);
 670 }
 671
 672 void
 673 _sethtent (int f)
 674 {
 675         if (!hostf)
 676                 hostf = fopen(_PATH_HOSTS, "rce" );
 677         else
 678                 rewind(hostf);
 679         stayopen = f;
 680 }
 681 libresolv_hidden_def (_sethtent)
 682
 683 void
 684 _endhtent (void)
 685 {
 686         if (hostf && !stayopen) {
 687                 (void) fclose(hostf);
 688                 hostf = NULL;
 689         }
 690 }
 691
 692 struct hostent *
 693 _gethtent (void)
 694 {
 695         char *p;
 696         char *cp, **q;
 697         int af, len;
 698
 699         if (!hostf && !(hostf = fopen(_PATH_HOSTS, "rce" ))) {
 700                 __set_h_errno (NETDB_INTERNAL);
 701                 return (NULL);
 702         }
 703  again:
 704         if (!(p = fgets(hostbuf, sizeof hostbuf, hostf))) {
 705                 __set_h_errno (HOST_NOT_FOUND);
 706                 return (NULL);
 707         }
 708         if (*p == '#')
 709                 goto again;
 710         if (!(cp = strpbrk(p, "#\n")))
 711                 goto again;
 712         *cp = '\0';
 713         if (!(cp = strpbrk(p, " \t")))
 714                 goto again;
 715         *cp++ = '\0';
 716         if (inet_pton(AF_INET6, p, host_addr) > 0) {
 717                 af = AF_INET6;
 718                 len = IN6ADDRSZ;
 719         } else if (inet_pton(AF_INET, p, host_addr) > 0) {
 720                 if (_res.options & RES_USE_INET6) {
 721                         map_v4v6_address((char*)host_addr, (char*)host_addr);
 722                         af = AF_INET6;
 723                         len = IN6ADDRSZ;
 724                 } else {
 725                         af = AF_INET;
 726                         len = INADDRSZ;
 727                 }
 728         } else {
 729                 goto again;
 730         }
 731         h_addr_ptrs[0] = (char *)host_addr;
 732         h_addr_ptrs[1] = NULL;
 733         host.h_addr_list = h_addr_ptrs;
 734         host.h_length = len;
 735         host.h_addrtype = af;
 736         while (*cp == ' ' || *cp == '\t')
 737                 cp++;
 738         host.h_name = cp;
 739         q = host.h_aliases = host_aliases;
 740         if ((cp = strpbrk(cp, " \t")))
 741                 *cp++ = '\0';
 742         while (cp && *cp) {
 743                 if (*cp == ' ' || *cp == '\t') {
 744                         cp++;
 745                         continue;
 746                 }
 747                 if (q < &host_aliases[MAXALIASES - 1])
 748                         *q++ = cp;
 749                 if ((cp = strpbrk(cp, " \t")))
 750                         *cp++ = '\0';
 751         }
 752         *q = NULL;
 753         __set_h_errno (NETDB_SUCCESS);
 754         return (&host);
 755 }
 756 libresolv_hidden_def (_gethtent)
 757
 758 struct hostent *
 759 _gethtbyname (const char *name)
 760 {
 761         struct hostent *hp;
 762
 763         if (_res.options & RES_USE_INET6) {
 764                 hp = _gethtbyname2(name, AF_INET6);
 765                 if (hp)
 766                         return (hp);
 767         }
 768         return (_gethtbyname2(name, AF_INET));
 769 }
 770
 771 struct hostent *
 772 _gethtbyname2 (const char *name, int af)
 773 {
 774         struct hostent *p;
 775         char **cp;
 776
 777         _sethtent(0);
 778         while ((p = _gethtent())) {
 779                 if (p->h_addrtype != af)
 780                         continue;
 781                 if (strcasecmp(p->h_name, name) == 0)
 782                         break;
 783                 for (cp = p->h_aliases; *cp != 0; cp++)
 784                         if (strcasecmp(*cp, name) == 0)
 785                                 goto found;
 786         }
 787  found:
 788         _endhtent();
 789         return (p);
 790 }
 791 libresolv_hidden_def (_gethtbyname2)
 792
 793 struct hostent *
 794 _gethtbyaddr (const char *addr, size_t len, int af)
 795 {
 796         struct hostent *p;
 797
 798         _sethtent(0);
 799         while ((p = _gethtent()))
 800                 if (p->h_addrtype == af && !memcmp(p->h_addr, addr, len))
 801                         break;
 802         _endhtent();
 803         return (p);
 804 }
 805 libresolv_hidden_def (_gethtbyaddr)
 806
 807 static void
 808 map_v4v6_address (const char *src, char *dst)
 809 {
 810         u_char *p = (u_char *)dst;
 811         char tmp[INADDRSZ];
 812         int i;
 813
 814         /* Stash a temporary copy so our caller can update in place. */
 815         memcpy(tmp, src, INADDRSZ);
 816         /* Mark this ipv6 addr as a mapped ipv4. */
 817         for (i = 0; i < 10; i++)
 818                 *p++ = 0x00;
 819         *p++ = 0xff;
 820         *p++ = 0xff;
 821         /* Retrieve the saved copy and we're done. */
 822         memcpy((void*)p, tmp, INADDRSZ);
 823 }
 824
 825 static void
 826 map_v4v6_hostent (struct hostent *hp, char **bpp, int *lenp)
 827 {
 828         char **ap;
 829
 830         if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
 831                 return;
 832         hp->h_addrtype = AF_INET6;
 833         hp->h_length = IN6ADDRSZ;
 834         for (ap = hp->h_addr_list; *ap; ap++) {
 835                 int i = sizeof(align) - ((u_long)*bpp % sizeof(align));
 836
 837                 if (*lenp < (i + IN6ADDRSZ)) {
 838                         /* Out of memory.  Truncate address list here.  XXX */
 839                         *ap = NULL;
 840                         return;
 841                 }
 842                 *bpp += i;
 843                 *lenp -= i;
 844                 map_v4v6_address(*ap, *bpp);
 845                 *ap = *bpp;
 846                 *bpp += IN6ADDRSZ;
 847                 *lenp -= IN6ADDRSZ;
 848         }
 849 }
 850
 851 extern void
 852 addrsort (char **ap, int num)
 853 {
 854         int i, j;
 855         char **p;
 856         short aval[MAXADDRS];
 857         int needsort = 0;
 858
 859         p = ap;
 860         for (i = 0; i < num; i++, p++) {
 861             for (j = 0 ; (unsigned)j < _res.nsort; j++)
 862                 if (_res.sort_list[j].addr.s_addr ==
 863                     (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 864                         break;
 865             aval[i] = j;
 866             if (needsort == 0 && i > 0 && j < aval[i-1])
 867                 needsort = i;
 868         }
 869         if (!needsort)
 870             return;
 871
 872         while (needsort < num) {
 873             for (j = needsort - 1; j >= 0; j--) {
 874                 if (aval[j] > aval[j+1]) {
 875                     char *hp;
 876
 877                     i = aval[j];
 878                     aval[j] = aval[j+1];
 879                     aval[j+1] = i;
 880
 881                     hp = ap[j];
 882                     ap[j] = ap[j+1];
 883                     ap[j+1] = hp;
 884
 885                 } else
 886                     break;
 887             }
 888             needsort++;
 889         }
 890 }