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  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by the University of
  18  *      California, Berkeley and its contributors.
  19  * 4. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  * -
  35  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  36  *
  37  * Permission to use, copy, modify, and distribute this software for any
  38  * purpose with or without fee is hereby granted, provided that the above
  39  * copyright notice and this permission notice appear in all copies, and that
  40  * the name of Digital Equipment Corporation not be used in advertising or
  41  * publicity pertaining to distribution of the document or software without
  42  * specific, written prior permission.
  43  *
  44  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  45  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  46  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  47  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  48  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  49  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  50  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  51  * SOFTWARE.
  52  * -
  53  * --Copyright--
  54  */
  55
  56 #if defined(LIBC_SCCS) && !defined(lint)
  57 static char sccsid[] = "@(#)gethostnamadr.c     8.1 (Berkeley) 6/4/93";
  58 static char rcsid[] = "$Id$";
  59 #endif /* LIBC_SCCS and not lint */
  60
  61 #include <sys/types.h>
  62 #include <sys/param.h>
  63 #include <sys/socket.h>
  64 #include <netinet/in.h>
  65 #include <arpa/inet.h>
  66 #include <arpa/nameser.h>
  67
  68 #include <stdio.h>
  69 #include <netdb.h>
  70 #include <resolv.h>
  71 #include <ctype.h>
  72 #include <errno.h>
  73 #include <syslog.h>
  74
  75 #ifndef LOG_AUTH
  76 # define LOG_AUTH 0
  77 #endif
  78
  79 #define MULTI_PTRS_ARE_ALIASES 1        /* XXX - experimental */
  80
  81 #if defined(BSD) && (BSD >= 199103) && defined(AF_INET6)
  82 # include <stdlib.h>
  83 # include <string.h>
  84 #else
  85 # include "../conf/portability.h"
  86 #endif
  87
  88 #if defined(USE_OPTIONS_H)
  89 # include <../conf/options.h>
  90 #endif
  91
  92 #ifdef SPRINTF_CHAR
  93 # define SPRINTF(x) strlen(sprintf/**/x)
  94 #else
  95 # define SPRINTF(x) ((size_t)sprintf x)
  96 #endif
  97
  98 #define MAXALIASES      35
  99 #define MAXADDRS        35
 100
 101 static const char AskedForGot[] =
 102                           "gethostby*.getanswer: asked for \"%s\", got \"%s\"";
 103
 104 static char *h_addr_ptrs[MAXADDRS + 1];
 105
 106 static struct hostent host;
 107 static char *host_aliases[MAXALIASES];
 108 static char hostbuf[8*1024];
 109 static u_char host_addr[16];    /* IPv4 or IPv6 */
 110 static FILE *hostf = NULL;
 111 static int stayopen = 0;
 112
 113 static void map_v4v6_address __P((const char *src, char *dst));
 114 static void map_v4v6_hostent __P((struct hostent *hp, char **bp, int *len));
 115
 116 #ifdef RESOLVSORT
 117 static void addrsort __P((char **, int));
 118 #endif
 119
 120 #if PACKETSZ > 1024
 121 #define MAXPACKET       PACKETSZ
 122 #else
 123 #define MAXPACKET       1024
 124 #endif
 125
 126 typedef union {
 127     HEADER hdr;
 128     u_char buf[MAXPACKET];
 129 } querybuf;
 130
 131 typedef union {
 132     int32_t al;
 133     char ac;
 134 } align;
 135
 136 extern int h_errno;
 137
 138 #ifdef DEBUG
 139 static void
 140 dprintf(msg, num)
 141         char *msg;
 142         int num;
 143 {
 144         if (_res.options & RES_DEBUG) {
 145                 int save = errno;
 146
 147                 printf(msg, num);
 148                 __set_errno (save);
 149         }
 150 }
 151 #else
 152 # define dprintf(msg, num) /*nada*/
 153 #endif
 154
 155 static struct hostent *
 156 getanswer(answer, anslen, qname, qtype)
 157         const querybuf *answer;
 158         int anslen;
 159         const char *qname;
 160         int qtype;
 161 {
 162         register const HEADER *hp;
 163         register const u_char *cp;
 164         register int n;
 165         const u_char *eom;
 166         char *bp, **ap, **hap;
 167         int type, class, buflen, ancount, qdcount;
 168         int haveanswer, had_error;
 169         int toobig = 0;
 170         char tbuf[MAXDNAME];
 171         const char *tname;
 172         int (*name_ok) __P((const char *));
 173
 174         tname = qname;
 175         host.h_name = NULL;
 176         eom = answer->buf + anslen;
 177         switch (qtype) {
 178         case T_A:
 179         case T_AAAA:
 180                 name_ok = res_hnok;
 181                 break;
 182         case T_PTR:
 183                 name_ok = res_dnok;
 184                 break;
 185         default:
 186                 return (NULL);  /* XXX should be abort(); */
 187         }
 188         /*
 189          * find first satisfactory answer
 190          */
 191         hp = &answer->hdr;
 192         ancount = ntohs(hp->ancount);
 193         qdcount = ntohs(hp->qdcount);
 194         bp = hostbuf;
 195         buflen = sizeof hostbuf;
 196         cp = answer->buf + HFIXEDSZ;
 197         if (qdcount != 1) {
 198                 __set_h_errno (NO_RECOVERY);
 199                 return (NULL);
 200         }
 201         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 202         if ((n < 0) || !(*name_ok)(bp)) {
 203                 __set_h_errno (NO_RECOVERY);
 204                 return (NULL);
 205         }
 206         cp += n + QFIXEDSZ;
 207         if (qtype == T_A || qtype == T_AAAA) {
 208                 /* res_send() has already verified that the query name is the
 209                  * same as the one we sent; this just gets the expanded name
 210                  * (i.e., with the succeeding search-domain tacked on).
 211                  */
 212                 n = strlen(bp) + 1;             /* for the \0 */
 213                 host.h_name = bp;
 214                 bp += n;
 215                 buflen -= n;
 216                 /* The qname can be abbreviated, but h_name is now absolute. */
 217                 qname = host.h_name;
 218         }
 219         ap = host_aliases;
 220         *ap = NULL;
 221         host.h_aliases = host_aliases;
 222         hap = h_addr_ptrs;
 223         *hap = NULL;
 224         host.h_addr_list = h_addr_ptrs;
 225         haveanswer = 0;
 226         had_error = 0;
 227         while (ancount-- > 0 && cp < eom && !had_error) {
 228                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 229                 if ((n < 0) || !(*name_ok)(bp)) {
 230                         had_error++;
 231                         continue;
 232                 }
 233                 cp += n;                        /* name */
 234                 type = _getshort(cp);
 235                 cp += INT16SZ;                  /* type */
 236                 class = _getshort(cp);
 237                 cp += INT16SZ + INT32SZ;        /* class, TTL */
 238                 n = _getshort(cp);
 239                 cp += INT16SZ;                  /* len */
 240                 if (class != C_IN) {
 241                         /* XXX - debug? syslog? */
 242                         cp += n;
 243                         continue;               /* XXX - had_error++ ? */
 244                 }
 245                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 246                         if (ap >= &host_aliases[MAXALIASES-1])
 247                                 continue;
 248                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 249                         if ((n < 0) || !(*name_ok)(tbuf)) {
 250                                 had_error++;
 251                                 continue;
 252                         }
 253                         cp += n;
 254                         /* Store alias. */
 255                         *ap++ = bp;
 256                         n = strlen(bp) + 1;     /* for the \0 */
 257                         bp += n;
 258                         buflen -= n;
 259                         /* Get canonical name. */
 260                         n = strlen(tbuf) + 1;   /* for the \0 */
 261                         if (n > buflen) {
 262                                 had_error++;
 263                                 continue;
 264                         }
 265                         strcpy(bp, tbuf);
 266                         host.h_name = bp;
 267                         bp += n;
 268                         buflen -= n;
 269                         continue;
 270                 }
 271                 if (qtype == T_PTR && type == T_CNAME) {
 272                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 273                         if ((n < 0) || !res_hnok(tbuf)) {
 274                                 had_error++;
 275                                 continue;
 276                         }
 277                         cp += n;
 278                         /* Get canonical name. */
 279                         n = strlen(tbuf) + 1;   /* for the \0 */
 280                         if (n > buflen) {
 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                         syslog(LOG_NOTICE|LOG_AUTH,
 292                "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
 293                                qname, p_class(C_IN), p_type(qtype),
 294                                p_type(type));
 295                         cp += n;
 296                         continue;               /* XXX - had_error++ ? */
 297                 }
 298                 switch (type) {
 299                 case T_PTR:
 300                         if (strcasecmp(tname, bp) != 0) {
 301                                 syslog(LOG_NOTICE|LOG_AUTH,
 302                                        AskedForGot, qname, bp);
 303                                 cp += n;
 304                                 continue;       /* XXX - had_error++ ? */
 305                         }
 306                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 307                         if ((n < 0) || !res_hnok(bp)) {
 308                                 had_error++;
 309                                 break;
 310                         }
 311 #if MULTI_PTRS_ARE_ALIASES
 312                         cp += n;
 313                         if (!haveanswer)
 314                                 host.h_name = bp;
 315                         else if (ap < &host_aliases[MAXALIASES-1])
 316                                 *ap++ = bp;
 317                         else
 318                                 n = -1;
 319                         if (n != -1) {
 320                                 n = strlen(bp) + 1;     /* for the \0 */
 321                                 bp += n;
 322                                 buflen -= n;
 323                         }
 324                         break;
 325 #else
 326                         host.h_name = bp;
 327                         if (_res.options & RES_USE_INET6) {
 328                                 n = strlen(bp) + 1;     /* for the \0 */
 329                                 bp += n;
 330                                 buflen -= n;
 331                                 map_v4v6_hostent(&host, &bp, &buflen);
 332                         }
 333                         __set_h_errno (NETDB_SUCCESS);
 334                         return (&host);
 335 #endif
 336                 case T_A:
 337                 case T_AAAA:
 338                         if (strcasecmp(host.h_name, bp) != 0) {
 339                                 syslog(LOG_NOTICE|LOG_AUTH,
 340                                        AskedForGot, host.h_name, bp);
 341                                 cp += n;
 342                                 continue;       /* XXX - had_error++ ? */
 343                         }
 344                         if (haveanswer) {
 345                                 if (n != host.h_length) {
 346                                         cp += n;
 347                                         continue;
 348                                 }
 349                         } else {
 350                                 register int nn;
 351
 352                                 host.h_name = bp;
 353                                 nn = strlen(bp) + 1;    /* for the \0 */
 354                                 bp += nn;
 355                                 buflen -= nn;
 356                         }
 357
 358                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 359
 360                         if (bp + n >= &hostbuf[sizeof hostbuf]) {
 361                                 dprintf("size (%d) too big\n", n);
 362                                 had_error++;
 363                                 continue;
 364                         }
 365                         if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
 366                                 if (!toobig++)
 367                                         dprintf("Too many addresses (%d)\n",
 368                                                 MAXADDRS);
 369                                 cp += n;
 370                                 continue;
 371                         }
 372                         bcopy(cp, *hap++ = bp, n);
 373                         bp += n;
 374                         buflen -= n;
 375                         cp += n;
 376                         break;
 377                 default:
 378                         abort();
 379                 }
 380                 if (!had_error)
 381                         haveanswer++;
 382         }
 383         if (haveanswer) {
 384                 *ap = NULL;
 385                 *hap = NULL;
 386 # if defined(RESOLVSORT)
 387                 /*
 388                  * Note: we sort even if host can take only one address
 389                  * in its return structures - should give it the "best"
 390                  * address in that case, not some random one
 391                  */
 392                 if (_res.nsort && haveanswer > 1 && qtype == T_A)
 393                         addrsort(h_addr_ptrs, haveanswer);
 394 # endif /*RESOLVSORT*/
 395                 if (!host.h_name) {
 396                         n = strlen(qname) + 1;  /* for the \0 */
 397                         if (n > buflen)
 398                                 goto try_again;
 399                         strcpy(bp, qname);
 400                         host.h_name = bp;
 401                         bp += n;
 402                         buflen -= n;
 403                 }
 404                 if (_res.options & RES_USE_INET6)
 405                         map_v4v6_hostent(&host, &bp, &buflen);
 406                 __set_h_errno (NETDB_SUCCESS);
 407                 return (&host);
 408         }
 409  try_again:
 410         __set_h_errno (TRY_AGAIN);
 411         return (NULL);
 412 }
 413
 414 struct hostent *
 415 gethostbyname(name)
 416         const char *name;
 417 {
 418         struct hostent *hp;
 419
 420         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 421                 __set_h_errno (NETDB_INTERNAL);
 422                 return (NULL);
 423        }
 424         if (_res.options & RES_USE_INET6) {
 425                 hp = gethostbyname2(name, AF_INET6);
 426                 if (hp)
 427                         return (hp);
 428         }
 429         return (gethostbyname2(name, AF_INET));
 430 }
 431
 432 struct hostent *
 433 gethostbyname2(name, af)
 434         const char *name;
 435         int af;
 436 {
 437         querybuf buf;
 438         register const char *cp;
 439         char *bp;
 440         int n, size, type, len;
 441         extern struct hostent *_gethtbyname2();
 442
 443         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 444                 __set_h_errno (NETDB_INTERNAL);
 445                 return (NULL);
 446         }
 447
 448         switch (af) {
 449         case AF_INET:
 450                 size = INADDRSZ;
 451                 type = T_A;
 452                 break;
 453         case AF_INET6:
 454                 size = IN6ADDRSZ;
 455                 type = T_AAAA;
 456                 break;
 457         default:
 458                 __set_h_errno (NETDB_INTERNAL);
 459                 errno = EAFNOSUPPORT;
 460                 return (NULL);
 461         }
 462
 463         host.h_addrtype = af;
 464         host.h_length = size;
 465
 466         /*
 467          * if there aren't any dots, it could be a user-level alias.
 468          * this is also done in res_query() since we are not the only
 469          * function that looks up host names.
 470          */
 471         if (!strchr(name, '.') && (cp = __hostalias(name)))
 472                 name = cp;
 473
 474         /*
 475          * disallow names consisting only of digits/dots, unless
 476          * they end in a dot.
 477          */
 478         if (isdigit(name[0]))
 479                 for (cp = name;; ++cp) {
 480                         if (!*cp) {
 481                                 if (*--cp == '.')
 482                                         break;
 483                                 /*
 484                                  * All-numeric, no dot at the end.
 485                                  * Fake up a hostent as if we'd actually
 486                                  * done a lookup.
 487                                  */
 488                                 if (inet_pton(af, name, host_addr) <= 0) {
 489                                         __set_h_errno (HOST_NOT_FOUND);
 490                                         return (NULL);
 491                                 }
 492                                 strncpy(hostbuf, name, MAXDNAME);
 493                                 hostbuf[MAXDNAME] = '\0';
 494                                 bp = hostbuf + MAXDNAME;
 495                                 len = sizeof hostbuf - MAXDNAME;
 496                                 host.h_name = hostbuf;
 497                                 host.h_aliases = host_aliases;
 498                                 host_aliases[0] = NULL;
 499                                 h_addr_ptrs[0] = (char *)host_addr;
 500                                 h_addr_ptrs[1] = NULL;
 501                                 host.h_addr_list = h_addr_ptrs;
 502                                 if (_res.options & RES_USE_INET6)
 503                                         map_v4v6_hostent(&host, &bp, &len);
 504                                 __set_h_errno (NETDB_SUCCESS);
 505                                 return (&host);
 506                         }
 507                         if (!isdigit(*cp) && *cp != '.')
 508                                 break;
 509                }
 510         if (isxdigit(name[0]) || name[0] == ':')
 511                 for (cp = name;; ++cp) {
 512                         if (!*cp) {
 513                                 if (*--cp == '.')
 514                                         break;
 515                                 /*
 516                                  * All-IPv6-legal, no dot at the end.
 517                                  * Fake up a hostent as if we'd actually
 518                                  * done a lookup.
 519                                  */
 520                                 if (inet_pton(af, name, host_addr) <= 0) {
 521                                         __set_h_errno (HOST_NOT_FOUND);
 522                                         return (NULL);
 523                                 }
 524                                 strncpy(hostbuf, name, MAXDNAME);
 525                                 hostbuf[MAXDNAME] = '\0';
 526                                 bp = hostbuf + MAXDNAME;
 527                                 len = sizeof hostbuf - MAXDNAME;
 528                                 host.h_name = hostbuf;
 529                                 host.h_aliases = host_aliases;
 530                                 host_aliases[0] = NULL;
 531                                 h_addr_ptrs[0] = (char *)host_addr;
 532                                 h_addr_ptrs[1] = NULL;
 533                                 host.h_addr_list = h_addr_ptrs;
 534                                 __set_h_errno (NETDB_SUCCESS);
 535                                 return (&host);
 536                         }
 537                         if (!isxdigit(*cp) && *cp != ':' && *cp != '.')
 538                                 break;
 539                 }
 540
 541         if ((n = res_search(name, C_IN, type, buf.buf, sizeof(buf))) < 0) {
 542                 dprintf("res_search failed (%d)\n", n);
 543                 if (errno == ECONNREFUSED)
 544                         return (_gethtbyname2(name, af));
 545                 return (NULL);
 546         }
 547         return (getanswer(&buf, n, name, type));
 548 }
 549
 550 struct hostent *
 551 gethostbyaddr(addr, len, af)
 552         const char *addr;       /* XXX should have been def'd as u_char! */
 553         int len, af;
 554 {
 555         const u_char *uaddr = (const u_char *)addr;
 556         static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
 557         static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
 558         int n, size;
 559         querybuf buf;
 560         register struct hostent *hp;
 561         char qbuf[MAXDNAME+1], *qp;
 562 #ifdef SUNSECURITY
 563         register struct hostent *rhp;
 564         char **haddr;
 565         u_long old_options;
 566         char hname2[MAXDNAME+1];
 567 #endif /*SUNSECURITY*/
 568         extern struct hostent *_gethtbyaddr();
 569
 570         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 571                 __set_h_errno (NETDB_INTERNAL);
 572                 return (NULL);
 573         }
 574         if (af == AF_INET6 && len == IN6ADDRSZ &&
 575             (!bcmp(uaddr, mapped, sizeof mapped) ||
 576              !bcmp(uaddr, tunnelled, sizeof tunnelled))) {
 577                 /* Unmap. */
 578                 addr += sizeof mapped;
 579                 uaddr += sizeof mapped;
 580                 af = AF_INET;
 581                 len = INADDRSZ;
 582         }
 583         switch (af) {
 584         case AF_INET:
 585                 size = INADDRSZ;
 586                 break;
 587         case AF_INET6:
 588                 size = IN6ADDRSZ;
 589                 break;
 590         default:
 591                 __set_errno (EAFNOSUPPORT);
 592                 __set_h_errno (NETDB_INTERNAL);
 593                 return (NULL);
 594         }
 595         if (size != len) {
 596                 __set_errno (EINVAL);
 597                 __set_h_errno (NETDB_INTERNAL);
 598                 return (NULL);
 599         }
 600         switch (af) {
 601         case AF_INET:
 602                 (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 603                                (uaddr[3] & 0xff),
 604                                (uaddr[2] & 0xff),
 605                                (uaddr[1] & 0xff),
 606                                (uaddr[0] & 0xff));
 607                 break;
 608         case AF_INET6:
 609                 qp = qbuf;
 610                 for (n = IN6ADDRSZ - 1; n >= 0; n--) {
 611                         qp += SPRINTF((qp, "%x.%x.",
 612                                        uaddr[n] & 0xf,
 613                                        (uaddr[n] >> 4) & 0xf));
 614                 }
 615                 strcpy(qp, "ip6.int");
 616                 break;
 617         default:
 618                 abort();
 619         }
 620         n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf.buf, sizeof buf.buf);
 621         if (n < 0) {
 622                 dprintf("res_query failed (%d)\n", n);
 623                 if (errno == ECONNREFUSED)
 624                         return (_gethtbyaddr(addr, len, af));
 625                 return (NULL);
 626         }
 627         if (!(hp = getanswer(&buf, n, qbuf, T_PTR)))
 628                 return (NULL);  /* h_errno was set by getanswer() */
 629 #ifdef SUNSECURITY
 630         if (af == AF_INET) {
 631             /*
 632              * turn off search as the name should be absolute,
 633              * 'localhost' should be matched by defnames
 634              */
 635             strncpy(hname2, hp->h_name, MAXDNAME);
 636             hname2[MAXDNAME] = '\0';
 637             old_options = _res.options;
 638             _res.options &= ~RES_DNSRCH;
 639             _res.options |= RES_DEFNAMES;
 640             if (!(rhp = gethostbyname(hname2))) {
 641                 syslog(LOG_NOTICE|LOG_AUTH,
 642                        "gethostbyaddr: No A record for %s (verifying [%s])",
 643                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 644                 _res.options = old_options;
 645                 __set_h_errno (HOST_NOT_FOUND);
 646                 return (NULL);
 647             }
 648             _res.options = old_options;
 649             for (haddr = rhp->h_addr_list; *haddr; haddr++)
 650                 if (!memcmp(*haddr, addr, INADDRSZ))
 651                         break;
 652             if (!*haddr) {
 653                 syslog(LOG_NOTICE|LOG_AUTH,
 654                        "gethostbyaddr: A record of %s != PTR record [%s]",
 655                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 656                 __set_h_errno (HOST_NOT_FOUND);
 657                 return (NULL);
 658             }
 659         }
 660 #endif /*SUNSECURITY*/
 661         hp->h_addrtype = af;
 662         hp->h_length = len;
 663         bcopy(addr, host_addr, len);
 664         h_addr_ptrs[0] = (char *)host_addr;
 665         h_addr_ptrs[1] = NULL;
 666         if (af == AF_INET && (_res.options & 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 void
 676 _sethtent(f)
 677         int f;
 678 {
 679         if (!hostf)
 680                 hostf = fopen(_PATH_HOSTS, "r" );
 681         else
 682                 rewind(hostf);
 683         stayopen = f;
 684 }
 685
 686 void
 687 _endhtent()
 688 {
 689         if (hostf && !stayopen) {
 690                 (void) fclose(hostf);
 691                 hostf = NULL;
 692         }
 693 }
 694
 695 struct hostent *
 696 _gethtent()
 697 {
 698         char *p;
 699         register char *cp, **q;
 700         int af, len;
 701
 702         if (!hostf && !(hostf = fopen(_PATH_HOSTS, "r" ))) {
 703                 __set_h_errno (NETDB_INTERNAL);
 704                 return (NULL);
 705         }
 706  again:
 707         if (!(p = fgets(hostbuf, sizeof hostbuf, hostf))) {
 708                 __set_h_errno (HOST_NOT_FOUND);
 709                 return (NULL);
 710         }
 711         if (*p == '#')
 712                 goto again;
 713         if (!(cp = strpbrk(p, "#\n")))
 714                 goto again;
 715         *cp = '\0';
 716         if (!(cp = strpbrk(p, " \t")))
 717                 goto again;
 718         *cp++ = '\0';
 719         if ((_res.options & RES_USE_INET6) &&
 720             inet_pton(AF_INET6, p, host_addr) > 0) {
 721                 af = AF_INET6;
 722                 len = IN6ADDRSZ;
 723         } else if (inet_pton(AF_INET, p, host_addr) > 0) {
 724                 if (_res.options & RES_USE_INET6) {
 725                         map_v4v6_address((char*)host_addr, (char*)host_addr);
 726                         af = AF_INET6;
 727                         len = IN6ADDRSZ;
 728                 } else {
 729                         af = AF_INET;
 730                         len = INADDRSZ;
 731                 }
 732         } else {
 733                 goto again;
 734         }
 735         h_addr_ptrs[0] = (char *)host_addr;
 736         h_addr_ptrs[1] = NULL;
 737         host.h_addr_list = h_addr_ptrs;
 738         host.h_length = len;
 739         host.h_addrtype = af;
 740         while (*cp == ' ' || *cp == '\t')
 741                 cp++;
 742         host.h_name = cp;
 743         q = host.h_aliases = host_aliases;
 744         if (cp = strpbrk(cp, " \t"))
 745                 *cp++ = '\0';
 746         while (cp && *cp) {
 747                 if (*cp == ' ' || *cp == '\t') {
 748                         cp++;
 749                         continue;
 750                 }
 751                 if (q < &host_aliases[MAXALIASES - 1])
 752                         *q++ = cp;
 753                 if (cp = strpbrk(cp, " \t"))
 754                         *cp++ = '\0';
 755         }
 756         *q = NULL;
 757         if (_res.options & RES_USE_INET6) {
 758                 char *bp = hostbuf;
 759                 int buflen = sizeof hostbuf;
 760
 761                 map_v4v6_hostent(&host, &bp, &buflen);
 762         }
 763         __set_h_errno (NETDB_SUCCESS);
 764         return (&host);
 765 }
 766
 767 struct hostent *
 768 _gethtbyname(name)
 769         const char *name;
 770 {
 771         extern struct hostent *_gethtbyname2();
 772         struct hostent *hp;
 773
 774         if (_res.options & RES_USE_INET6) {
 775                 hp = _gethtbyname2(name, AF_INET6);
 776                 if (hp)
 777                         return (hp);
 778         }
 779         return (_gethtbyname2(name, AF_INET));
 780 }
 781
 782 struct hostent *
 783 _gethtbyname2(name, af)
 784         const char *name;
 785         int af;
 786 {
 787         register struct hostent *p;
 788         register char **cp;
 789
 790         _sethtent(0);
 791         while (p = _gethtent()) {
 792                 if (p->h_addrtype != af)
 793                         continue;
 794                 if (strcasecmp(p->h_name, name) == 0)
 795                         break;
 796                 for (cp = p->h_aliases; *cp != 0; cp++)
 797                         if (strcasecmp(*cp, name) == 0)
 798                                 goto found;
 799         }
 800  found:
 801         _endhtent();
 802         return (p);
 803 }
 804
 805 struct hostent *
 806 _gethtbyaddr(addr, len, af)
 807         const char *addr;
 808         int len, af;
 809 {
 810         register struct hostent *p;
 811
 812         _sethtent(0);
 813         while (p = _gethtent())
 814                 if (p->h_addrtype == af && !bcmp(p->h_addr, addr, len))
 815                         break;
 816         _endhtent();
 817         return (p);
 818 }
 819
 820 static void
 821 map_v4v6_address(src, dst)
 822         const char *src;
 823         char *dst;
 824 {
 825         u_char *p = (u_char *)dst;
 826         char tmp[INADDRSZ];
 827         int i;
 828
 829         /* Stash a temporary copy so our caller can update in place. */
 830         bcopy(src, tmp, INADDRSZ);
 831         /* Mark this ipv6 addr as a mapped ipv4. */
 832         for (i = 0; i < 10; i++)
 833                 *p++ = 0x00;
 834         *p++ = 0xff;
 835         *p++ = 0xff;
 836         /* Retrieve the saved copy and we're done. */
 837         bcopy(tmp, (void*)p, INADDRSZ);
 838 }
 839
 840 static void
 841 map_v4v6_hostent(hp, bpp, lenp)
 842         struct hostent *hp;
 843         char **bpp;
 844         int *lenp;
 845 {
 846         char **ap;
 847
 848         if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
 849                 return;
 850         hp->h_addrtype = AF_INET6;
 851         hp->h_length = IN6ADDRSZ;
 852         for (ap = hp->h_addr_list; *ap; ap++) {
 853                 int i = sizeof(align) - ((u_long)*bpp % sizeof(align));
 854
 855                 if (*lenp < (i + IN6ADDRSZ)) {
 856                         /* Out of memory.  Truncate address list here.  XXX */
 857                         *ap = NULL;
 858                         return;
 859                 }
 860                 *bpp += i;
 861                 *lenp -= i;
 862                 map_v4v6_address(*ap, *bpp);
 863                 *ap = *bpp;
 864                 *bpp += IN6ADDRSZ;
 865                 *lenp -= IN6ADDRSZ;
 866         }
 867 }
 868
 869 #ifdef RESOLVSORT
 870 static void
 871 addrsort(ap, num)
 872         char **ap;
 873         int num;
 874 {
 875         int i, j;
 876         char **p;
 877         short aval[MAXADDRS];
 878         int needsort = 0;
 879
 880         p = ap;
 881         for (i = 0; i < num; i++, p++) {
 882             for (j = 0 ; (unsigned)j < _res.nsort; j++)
 883                 if (_res.sort_list[j].addr.s_addr ==
 884                     (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 885                         break;
 886             aval[i] = j;
 887             if (needsort == 0 && i > 0 && j < aval[i-1])
 888                 needsort = i;
 889         }
 890         if (!needsort)
 891             return;
 892
 893         while (needsort < num) {
 894             for (j = needsort - 1; j >= 0; j--) {
 895                 if (aval[j] > aval[j+1]) {
 896                     char *hp;
 897
 898                     i = aval[j];
 899                     aval[j] = aval[j+1];
 900                     aval[j+1] = i;
 901
 902                     hp = ap[j];
 903                     ap[j] = ap[j+1];
 904                     ap[j+1] = hp;
 905
 906                 } else
 907                     break;
 908             }
 909             needsort++;
 910         }
 911 }
 912 #endif
 913
 914 #if defined(BSD43_BSD43_NFS) || defined(sun)
 915 /* some libc's out there are bound internally to these names (UMIPS) */
 916 void
 917 ht_sethostent(stayopen)
 918         int stayopen;
 919 {
 920         _sethtent(stayopen);
 921 }
 922
 923 void
 924 ht_endhostent()
 925 {
 926         _endhtent();
 927 }
 928
 929 struct hostent *
 930 ht_gethostbyname(name)
 931         char *name;
 932 {
 933         return (_gethtbyname(name));
 934 }
 935
 936 struct hostent *
 937 ht_gethostbyaddr(addr, len, af)
 938         const char *addr;
 939         int len, af;
 940 {
 941         return (_gethtbyaddr(addr, len, af));
 942 }
 943
 944 struct hostent *
 945 gethostent()
 946 {
 947         return (_gethtent());
 948 }
 949
 950 void
 951 dns_service()
 952 {
 953         return;
 954 }
 955
 956 #undef dn_skipname
 957 dn_skipname(comp_dn, eom)
 958         const u_char *comp_dn, *eom;
 959 {
 960         return (__dn_skipname(comp_dn, eom));
 961 }
 962 #endif /*old-style libc with yp junk in it*/