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 /* As per RFC 1034 and 1035 a host name cannot exceed 255 octets in length.  */
 127 #ifdef MAXHOSTNAMELEN
 128 # undef MAXHOSTNAMELEN
 129 #endif
 130 #define MAXHOSTNAMELEN 256
 131
 132 typedef union {
 133     HEADER hdr;
 134     u_char buf[MAXPACKET];
 135 } querybuf;
 136
 137 typedef union {
 138     int32_t al;
 139     char ac;
 140 } align;
 141
 142 #ifndef h_errno
 143 extern int h_errno;
 144 #endif
 145
 146 #ifdef DEBUG
 147 static void
 148 dprintf(msg, num)
 149         char *msg;
 150         int num;
 151 {
 152         if (_res.options & RES_DEBUG) {
 153                 int save = errno;
 154
 155                 printf(msg, num);
 156                 __set_errno (save);
 157         }
 158 }
 159 #else
 160 # define dprintf(msg, num) /*nada*/
 161 #endif
 162
 163 static struct hostent *
 164 getanswer(answer, anslen, qname, qtype)
 165         const querybuf *answer;
 166         int anslen;
 167         const char *qname;
 168         int qtype;
 169 {
 170         register const HEADER *hp;
 171         register const u_char *cp;
 172         register int n;
 173         const u_char *eom;
 174         char *bp, **ap, **hap;
 175         int type, class, buflen, ancount, qdcount;
 176         int haveanswer, had_error;
 177         int toobig = 0;
 178         char tbuf[MAXDNAME];
 179         const char *tname;
 180         int (*name_ok) __P((const char *));
 181
 182         tname = qname;
 183         host.h_name = NULL;
 184         eom = answer->buf + anslen;
 185         switch (qtype) {
 186         case T_A:
 187         case T_AAAA:
 188                 name_ok = res_hnok;
 189                 break;
 190         case T_PTR:
 191                 name_ok = res_dnok;
 192                 break;
 193         default:
 194                 return (NULL);  /* XXX should be abort(); */
 195         }
 196         /*
 197          * find first satisfactory answer
 198          */
 199         hp = &answer->hdr;
 200         ancount = ntohs(hp->ancount);
 201         qdcount = ntohs(hp->qdcount);
 202         bp = hostbuf;
 203         buflen = sizeof hostbuf;
 204         cp = answer->buf + HFIXEDSZ;
 205         if (qdcount != 1) {
 206                 __set_h_errno (NO_RECOVERY);
 207                 return (NULL);
 208         }
 209         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 210         if ((n < 0) || !(*name_ok)(bp)) {
 211                 __set_h_errno (NO_RECOVERY);
 212                 return (NULL);
 213         }
 214         cp += n + QFIXEDSZ;
 215         if (qtype == T_A || qtype == T_AAAA) {
 216                 /* res_send() has already verified that the query name is the
 217                  * same as the one we sent; this just gets the expanded name
 218                  * (i.e., with the succeeding search-domain tacked on).
 219                  */
 220                 n = strlen(bp) + 1;             /* for the \0 */
 221                 if (n >= MAXHOSTNAMELEN) {
 222                         __set_h_errno (NO_RECOVERY);
 223                         return (NULL);
 224                 }
 225                 host.h_name = bp;
 226                 bp += n;
 227                 buflen -= n;
 228                 /* The qname can be abbreviated, but h_name is now absolute. */
 229                 qname = host.h_name;
 230         }
 231         ap = host_aliases;
 232         *ap = NULL;
 233         host.h_aliases = host_aliases;
 234         hap = h_addr_ptrs;
 235         *hap = NULL;
 236         host.h_addr_list = h_addr_ptrs;
 237         haveanswer = 0;
 238         had_error = 0;
 239         while (ancount-- > 0 && cp < eom && !had_error) {
 240                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 241                 if ((n < 0) || !(*name_ok)(bp)) {
 242                         had_error++;
 243                         continue;
 244                 }
 245                 cp += n;                        /* name */
 246                 type = _getshort(cp);
 247                 cp += INT16SZ;                  /* type */
 248                 class = _getshort(cp);
 249                 cp += INT16SZ + INT32SZ;        /* class, TTL */
 250                 n = _getshort(cp);
 251                 cp += INT16SZ;                  /* len */
 252                 if (class != C_IN) {
 253                         /* XXX - debug? syslog? */
 254                         cp += n;
 255                         continue;               /* XXX - had_error++ ? */
 256                 }
 257                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 258                         if (ap >= &host_aliases[MAXALIASES-1])
 259                                 continue;
 260                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 261                         if ((n < 0) || !(*name_ok)(tbuf)) {
 262                                 had_error++;
 263                                 continue;
 264                         }
 265                         cp += n;
 266                         /* Store alias. */
 267                         *ap++ = bp;
 268                         n = strlen(bp) + 1;     /* for the \0 */
 269                         if (n >= MAXHOSTNAMELEN) {
 270                                 had_error++;
 271                                 continue;
 272                         }
 273                         bp += n;
 274                         buflen -= n;
 275                         /* Get canonical name. */
 276                         n = strlen(tbuf) + 1;   /* for the \0 */
 277                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 278                                 had_error++;
 279                                 continue;
 280                         }
 281                         strcpy(bp, tbuf);
 282                         host.h_name = bp;
 283                         bp += n;
 284                         buflen -= n;
 285                         continue;
 286                 }
 287                 if (qtype == T_PTR && type == T_CNAME) {
 288                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 289                         if (n < 0 || !res_hnok(tbuf)) {
 290                                 had_error++;
 291                                 continue;
 292                         }
 293                         cp += n;
 294                         /* Get canonical name. */
 295                         n = strlen(tbuf) + 1;   /* for the \0 */
 296                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 297                                 had_error++;
 298                                 continue;
 299                         }
 300                         strcpy(bp, tbuf);
 301                         tname = bp;
 302                         bp += n;
 303                         buflen -= n;
 304                         continue;
 305                 }
 306                 if (type != qtype) {
 307                         syslog(LOG_NOTICE|LOG_AUTH,
 308                "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
 309                                qname, p_class(C_IN), p_type(qtype),
 310                                p_type(type));
 311                         cp += n;
 312                         continue;               /* XXX - had_error++ ? */
 313                 }
 314                 switch (type) {
 315                 case T_PTR:
 316                         if (strcasecmp(tname, bp) != 0) {
 317                                 syslog(LOG_NOTICE|LOG_AUTH,
 318                                        AskedForGot, qname, bp);
 319                                 cp += n;
 320                                 continue;       /* XXX - had_error++ ? */
 321                         }
 322                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 323                         if ((n < 0) || !res_hnok(bp)) {
 324                                 had_error++;
 325                                 break;
 326                         }
 327 #if MULTI_PTRS_ARE_ALIASES
 328                         cp += n;
 329                         if (!haveanswer)
 330                                 host.h_name = bp;
 331                         else if (ap < &host_aliases[MAXALIASES-1])
 332                                 *ap++ = bp;
 333                         else
 334                                 n = -1;
 335                         if (n != -1) {
 336                                 n = strlen(bp) + 1;     /* for the \0 */
 337                                 if (n >= MAXHOSTNAMELEN) {
 338                                         had_error++;
 339                                         break;
 340                                 }
 341                                 bp += n;
 342                                 buflen -= n;
 343                         }
 344                         break;
 345 #else
 346                         host.h_name = bp;
 347                         if (_res.options & RES_USE_INET6) {
 348                                 n = strlen(bp) + 1;     /* for the \0 */
 349                                 if (n >= MAXHOSTNAMELEN) {
 350                                         had_error++;
 351                                         break;
 352                                 }
 353                                 bp += n;
 354                                 buflen -= n;
 355                                 map_v4v6_hostent(&host, &bp, &buflen);
 356                         }
 357                         __set_h_errno (NETDB_SUCCESS);
 358                         return (&host);
 359 #endif
 360                 case T_A:
 361                 case T_AAAA:
 362                         if (strcasecmp(host.h_name, bp) != 0) {
 363                                 syslog(LOG_NOTICE|LOG_AUTH,
 364                                        AskedForGot, host.h_name, bp);
 365                                 cp += n;
 366                                 continue;       /* XXX - had_error++ ? */
 367                         }
 368                         if (n != host.h_length) {
 369                                 cp += n;
 370                                 continue;
 371                         }
 372                         if (!haveanswer) {
 373                                 register int nn;
 374
 375                                 host.h_name = bp;
 376                                 nn = strlen(bp) + 1;    /* for the \0 */
 377                                 bp += nn;
 378                                 buflen -= nn;
 379                         }
 380
 381                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 382
 383                         if (bp + n >= &hostbuf[sizeof hostbuf]) {
 384                                 dprintf("size (%d) too big\n", n);
 385                                 had_error++;
 386                                 continue;
 387                         }
 388                         if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
 389                                 if (!toobig++)
 390                                         dprintf("Too many addresses (%d)\n",
 391                                                 MAXADDRS);
 392                                 cp += n;
 393                                 continue;
 394                         }
 395                         bcopy(cp, *hap++ = bp, n);
 396                         bp += n;
 397                         buflen -= n;
 398                         cp += n;
 399                         break;
 400                 default:
 401                         abort();
 402                 }
 403                 if (!had_error)
 404                         haveanswer++;
 405         }
 406         if (haveanswer) {
 407                 *ap = NULL;
 408                 *hap = NULL;
 409 # if defined(RESOLVSORT)
 410                 /*
 411                  * Note: we sort even if host can take only one address
 412                  * in its return structures - should give it the "best"
 413                  * address in that case, not some random one
 414                  */
 415                 if (_res.nsort && haveanswer > 1 && qtype == T_A)
 416                         addrsort(h_addr_ptrs, haveanswer);
 417 # endif /*RESOLVSORT*/
 418                 if (!host.h_name) {
 419                         n = strlen(qname) + 1;  /* for the \0 */
 420                         if (n > buflen || n >= MAXHOSTNAMELEN)
 421                                 goto no_recovery;
 422                         strcpy(bp, qname);
 423                         host.h_name = bp;
 424                         bp += n;
 425                         buflen -= n;
 426                 }
 427                 if (_res.options & RES_USE_INET6)
 428                         map_v4v6_hostent(&host, &bp, &buflen);
 429                 __set_h_errno (NETDB_SUCCESS);
 430                 return (&host);
 431         }
 432  no_recovery:
 433         __set_h_errno (NO_RECOVERY);
 434         return (NULL);
 435 }
 436
 437 struct hostent *
 438 gethostbyname(name)
 439         const char *name;
 440 {
 441         struct hostent *hp;
 442
 443         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 444                 __set_h_errno (NETDB_INTERNAL);
 445                 return (NULL);
 446        }
 447         if (_res.options & RES_USE_INET6) {
 448                 hp = gethostbyname2(name, AF_INET6);
 449                 if (hp)
 450                         return (hp);
 451         }
 452         return (gethostbyname2(name, AF_INET));
 453 }
 454
 455 struct hostent *
 456 gethostbyname2(name, af)
 457         const char *name;
 458         int af;
 459 {
 460         querybuf buf;
 461         register const char *cp;
 462         char *bp;
 463         int n, size, type, len;
 464         extern struct hostent *_gethtbyname2();
 465
 466         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 467                 __set_h_errno (NETDB_INTERNAL);
 468                 return (NULL);
 469         }
 470
 471         switch (af) {
 472         case AF_INET:
 473                 size = INADDRSZ;
 474                 type = T_A;
 475                 break;
 476         case AF_INET6:
 477                 size = IN6ADDRSZ;
 478                 type = T_AAAA;
 479                 break;
 480         default:
 481                 __set_h_errno (NETDB_INTERNAL);
 482                 __set_errno (EAFNOSUPPORT);
 483                 return (NULL);
 484         }
 485
 486         host.h_addrtype = af;
 487         host.h_length = size;
 488
 489         /*
 490          * if there aren't any dots, it could be a user-level alias.
 491          * this is also done in res_query() since we are not the only
 492          * function that looks up host names.
 493          */
 494         if (!strchr(name, '.') && (cp = __hostalias(name)))
 495                 name = cp;
 496
 497         /*
 498          * disallow names consisting only of digits/dots, unless
 499          * they end in a dot.
 500          */
 501         if (isdigit(name[0]))
 502                 for (cp = name;; ++cp) {
 503                         if (!*cp) {
 504                                 if (*--cp == '.')
 505                                         break;
 506                                 /*
 507                                  * All-numeric, no dot at the end.
 508                                  * Fake up a hostent as if we'd actually
 509                                  * done a lookup.
 510                                  */
 511                                 if (inet_pton(af, name, host_addr) <= 0) {
 512                                         __set_h_errno (HOST_NOT_FOUND);
 513                                         return (NULL);
 514                                 }
 515                                 strncpy(hostbuf, name, MAXDNAME);
 516                                 hostbuf[MAXDNAME] = '\0';
 517                                 bp = hostbuf + MAXDNAME;
 518                                 len = sizeof hostbuf - MAXDNAME;
 519                                 host.h_name = hostbuf;
 520                                 host.h_aliases = host_aliases;
 521                                 host_aliases[0] = NULL;
 522                                 h_addr_ptrs[0] = (char *)host_addr;
 523                                 h_addr_ptrs[1] = NULL;
 524                                 host.h_addr_list = h_addr_ptrs;
 525                                 if (_res.options & RES_USE_INET6)
 526                                         map_v4v6_hostent(&host, &bp, &len);
 527                                 __set_h_errno (NETDB_SUCCESS);
 528                                 return (&host);
 529                         }
 530                         if (!isdigit(*cp) && *cp != '.')
 531                                 break;
 532                }
 533         if ((isxdigit(name[0]) && strchr(name, ':') != NULL) ||
 534             name[0] == ':')
 535                 for (cp = name;; ++cp) {
 536                         if (!*cp) {
 537                                 if (*--cp == '.')
 538                                         break;
 539                                 /*
 540                                  * All-IPv6-legal, no dot at the end.
 541                                  * Fake up a hostent as if we'd actually
 542                                  * done a lookup.
 543                                  */
 544                                 if (inet_pton(af, name, host_addr) <= 0) {
 545                                         __set_h_errno (HOST_NOT_FOUND);
 546                                         return (NULL);
 547                                 }
 548                                 strncpy(hostbuf, name, MAXDNAME);
 549                                 hostbuf[MAXDNAME] = '\0';
 550                                 bp = hostbuf + MAXDNAME;
 551                                 len = sizeof hostbuf - MAXDNAME;
 552                                 host.h_name = hostbuf;
 553                                 host.h_aliases = host_aliases;
 554                                 host_aliases[0] = NULL;
 555                                 h_addr_ptrs[0] = (char *)host_addr;
 556                                 h_addr_ptrs[1] = NULL;
 557                                 host.h_addr_list = h_addr_ptrs;
 558                                 __set_h_errno (NETDB_SUCCESS);
 559                                 return (&host);
 560                         }
 561                         if (!isxdigit(*cp) && *cp != ':' && *cp != '.')
 562                                 break;
 563                 }
 564
 565         if ((n = res_search(name, C_IN, type, buf.buf, sizeof(buf.buf))) < 0) {
 566                 dprintf("res_search failed (%d)\n", n);
 567                 if (errno == ECONNREFUSED)
 568                         return (_gethtbyname2(name, af));
 569                 return (NULL);
 570         }
 571         return (getanswer(&buf, n, name, type));
 572 }
 573
 574 struct hostent *
 575 gethostbyaddr(addr, len, af)
 576         const char *addr;       /* XXX should have been def'd as u_char! */
 577         int len, af;
 578 {
 579         const u_char *uaddr = (const u_char *)addr;
 580         static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
 581         static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
 582         int n, size;
 583         querybuf buf;
 584         register struct hostent *hp;
 585         char qbuf[MAXDNAME+1], *qp;
 586 #ifdef SUNSECURITY
 587         register struct hostent *rhp;
 588         char **haddr;
 589         u_long old_options;
 590         char hname2[MAXDNAME+1];
 591 #endif /*SUNSECURITY*/
 592         extern struct hostent *_gethtbyaddr();
 593
 594         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 595                 __set_h_errno (NETDB_INTERNAL);
 596                 return (NULL);
 597         }
 598         if (af == AF_INET6 && len == IN6ADDRSZ &&
 599             (!bcmp(uaddr, mapped, sizeof mapped) ||
 600              !bcmp(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.int");
 640                 break;
 641         default:
 642                 abort();
 643         }
 644         n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf.buf, sizeof buf.buf);
 645         if (n < 0) {
 646                 dprintf("res_query failed (%d)\n", n);
 647                 if (errno == ECONNREFUSED)
 648                         return (_gethtbyaddr(addr, len, af));
 649                 return (NULL);
 650         }
 651         if (!(hp = getanswer(&buf, n, qbuf, T_PTR)))
 652                 return (NULL);  /* h_errno was set by getanswer() */
 653 #ifdef SUNSECURITY
 654         if (af == AF_INET) {
 655             /*
 656              * turn off search as the name should be absolute,
 657              * 'localhost' should be matched by defnames
 658              */
 659             strncpy(hname2, hp->h_name, MAXDNAME);
 660             hname2[MAXDNAME] = '\0';
 661             old_options = _res.options;
 662             _res.options &= ~RES_DNSRCH;
 663             _res.options |= RES_DEFNAMES;
 664             if (!(rhp = gethostbyname(hname2))) {
 665                 syslog(LOG_NOTICE|LOG_AUTH,
 666                        "gethostbyaddr: No A record for %s (verifying [%s])",
 667                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 668                 _res.options = old_options;
 669                 __set_h_errno (HOST_NOT_FOUND);
 670                 return (NULL);
 671             }
 672             _res.options = old_options;
 673             for (haddr = rhp->h_addr_list; *haddr; haddr++)
 674                 if (!memcmp(*haddr, addr, INADDRSZ))
 675                         break;
 676             if (!*haddr) {
 677                 syslog(LOG_NOTICE|LOG_AUTH,
 678                        "gethostbyaddr: A record of %s != PTR record [%s]",
 679                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 680                 __set_h_errno (HOST_NOT_FOUND);
 681                 return (NULL);
 682             }
 683         }
 684 #endif /*SUNSECURITY*/
 685         hp->h_addrtype = af;
 686         hp->h_length = len;
 687         bcopy(addr, host_addr, len);
 688         h_addr_ptrs[0] = (char *)host_addr;
 689         h_addr_ptrs[1] = NULL;
 690         if (af == AF_INET && (_res.options & RES_USE_INET6)) {
 691                 map_v4v6_address((char*)host_addr, (char*)host_addr);
 692                 hp->h_addrtype = AF_INET6;
 693                 hp->h_length = IN6ADDRSZ;
 694         }
 695         __set_h_errno (NETDB_SUCCESS);
 696         return (hp);
 697 }
 698
 699 void
 700 _sethtent(f)
 701         int f;
 702 {
 703         if (!hostf)
 704                 hostf = fopen(_PATH_HOSTS, "r" );
 705         else
 706                 rewind(hostf);
 707         stayopen = f;
 708 }
 709
 710 void
 711 _endhtent()
 712 {
 713         if (hostf && !stayopen) {
 714                 (void) fclose(hostf);
 715                 hostf = NULL;
 716         }
 717 }
 718
 719 struct hostent *
 720 _gethtent()
 721 {
 722         char *p;
 723         register char *cp, **q;
 724         int af, len;
 725
 726         if (!hostf && !(hostf = fopen(_PATH_HOSTS, "r" ))) {
 727                 __set_h_errno (NETDB_INTERNAL);
 728                 return (NULL);
 729         }
 730  again:
 731         if (!(p = fgets(hostbuf, sizeof hostbuf, hostf))) {
 732                 __set_h_errno (HOST_NOT_FOUND);
 733                 return (NULL);
 734         }
 735         if (*p == '#')
 736                 goto again;
 737         if (!(cp = strpbrk(p, "#\n")))
 738                 goto again;
 739         *cp = '\0';
 740         if (!(cp = strpbrk(p, " \t")))
 741                 goto again;
 742         *cp++ = '\0';
 743         if (inet_pton(AF_INET6, p, host_addr) > 0) {
 744                 af = AF_INET6;
 745                 len = IN6ADDRSZ;
 746         } else if (inet_pton(AF_INET, p, host_addr) > 0) {
 747                 if (_res.options & RES_USE_INET6) {
 748                         map_v4v6_address((char*)host_addr, (char*)host_addr);
 749                         af = AF_INET6;
 750                         len = IN6ADDRSZ;
 751                 } else {
 752                         af = AF_INET;
 753                         len = INADDRSZ;
 754                 }
 755         } else {
 756                 goto again;
 757         }
 758         h_addr_ptrs[0] = (char *)host_addr;
 759         h_addr_ptrs[1] = NULL;
 760         host.h_addr_list = h_addr_ptrs;
 761         host.h_length = len;
 762         host.h_addrtype = af;
 763         while (*cp == ' ' || *cp == '\t')
 764                 cp++;
 765         host.h_name = cp;
 766         q = host.h_aliases = host_aliases;
 767         if (cp = strpbrk(cp, " \t"))
 768                 *cp++ = '\0';
 769         while (cp && *cp) {
 770                 if (*cp == ' ' || *cp == '\t') {
 771                         cp++;
 772                         continue;
 773                 }
 774                 if (q < &host_aliases[MAXALIASES - 1])
 775                         *q++ = cp;
 776                 if (cp = strpbrk(cp, " \t"))
 777                         *cp++ = '\0';
 778         }
 779         *q = NULL;
 780         __set_h_errno (NETDB_SUCCESS);
 781         return (&host);
 782 }
 783
 784 struct hostent *
 785 _gethtbyname(name)
 786         const char *name;
 787 {
 788         extern struct hostent *_gethtbyname2();
 789         struct hostent *hp;
 790
 791         if (_res.options & RES_USE_INET6) {
 792                 hp = _gethtbyname2(name, AF_INET6);
 793                 if (hp)
 794                         return (hp);
 795         }
 796         return (_gethtbyname2(name, AF_INET));
 797 }
 798
 799 struct hostent *
 800 _gethtbyname2(name, af)
 801         const char *name;
 802         int af;
 803 {
 804         register struct hostent *p;
 805         register char **cp;
 806
 807         _sethtent(0);
 808         while (p = _gethtent()) {
 809                 if (p->h_addrtype != af)
 810                         continue;
 811                 if (strcasecmp(p->h_name, name) == 0)
 812                         break;
 813                 for (cp = p->h_aliases; *cp != 0; cp++)
 814                         if (strcasecmp(*cp, name) == 0)
 815                                 goto found;
 816         }
 817  found:
 818         _endhtent();
 819         return (p);
 820 }
 821
 822 struct hostent *
 823 _gethtbyaddr(addr, len, af)
 824         const char *addr;
 825         int len, af;
 826 {
 827         register struct hostent *p;
 828
 829         _sethtent(0);
 830         while (p = _gethtent())
 831                 if (p->h_addrtype == af && !bcmp(p->h_addr, addr, len))
 832                         break;
 833         _endhtent();
 834         return (p);
 835 }
 836
 837 static void
 838 map_v4v6_address(src, dst)
 839         const char *src;
 840         char *dst;
 841 {
 842         u_char *p = (u_char *)dst;
 843         char tmp[INADDRSZ];
 844         int i;
 845
 846         /* Stash a temporary copy so our caller can update in place. */
 847         bcopy(src, tmp, INADDRSZ);
 848         /* Mark this ipv6 addr as a mapped ipv4. */
 849         for (i = 0; i < 10; i++)
 850                 *p++ = 0x00;
 851         *p++ = 0xff;
 852         *p++ = 0xff;
 853         /* Retrieve the saved copy and we're done. */
 854         bcopy(tmp, (void*)p, INADDRSZ);
 855 }
 856
 857 static void
 858 map_v4v6_hostent(hp, bpp, lenp)
 859         struct hostent *hp;
 860         char **bpp;
 861         int *lenp;
 862 {
 863         char **ap;
 864
 865         if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
 866                 return;
 867         hp->h_addrtype = AF_INET6;
 868         hp->h_length = IN6ADDRSZ;
 869         for (ap = hp->h_addr_list; *ap; ap++) {
 870                 int i = sizeof(align) - ((u_long)*bpp % sizeof(align));
 871
 872                 if (*lenp < (i + IN6ADDRSZ)) {
 873                         /* Out of memory.  Truncate address list here.  XXX */
 874                         *ap = NULL;
 875                         return;
 876                 }
 877                 *bpp += i;
 878                 *lenp -= i;
 879                 map_v4v6_address(*ap, *bpp);
 880                 *ap = *bpp;
 881                 *bpp += IN6ADDRSZ;
 882                 *lenp -= IN6ADDRSZ;
 883         }
 884 }
 885
 886 #ifdef RESOLVSORT
 887 static void
 888 addrsort(ap, num)
 889         char **ap;
 890         int num;
 891 {
 892         int i, j;
 893         char **p;
 894         short aval[MAXADDRS];
 895         int needsort = 0;
 896
 897         p = ap;
 898         for (i = 0; i < num; i++, p++) {
 899             for (j = 0 ; (unsigned)j < _res.nsort; j++)
 900                 if (_res.sort_list[j].addr.s_addr ==
 901                     (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 902                         break;
 903             aval[i] = j;
 904             if (needsort == 0 && i > 0 && j < aval[i-1])
 905                 needsort = i;
 906         }
 907         if (!needsort)
 908             return;
 909
 910         while (needsort < num) {
 911             for (j = needsort - 1; j >= 0; j--) {
 912                 if (aval[j] > aval[j+1]) {
 913                     char *hp;
 914
 915                     i = aval[j];
 916                     aval[j] = aval[j+1];
 917                     aval[j+1] = i;
 918
 919                     hp = ap[j];
 920                     ap[j] = ap[j+1];
 921                     ap[j+1] = hp;
 922
 923                 } else
 924                     break;
 925             }
 926             needsort++;
 927         }
 928 }
 929 #endif
 930
 931 #if defined(BSD43_BSD43_NFS) || defined(sun)
 932 /* some libc's out there are bound internally to these names (UMIPS) */
 933 void
 934 ht_sethostent(stayopen)
 935         int stayopen;
 936 {
 937         _sethtent(stayopen);
 938 }
 939
 940 void
 941 ht_endhostent()
 942 {
 943         _endhtent();
 944 }
 945
 946 struct hostent *
 947 ht_gethostbyname(name)
 948         char *name;
 949 {
 950         return (_gethtbyname(name));
 951 }
 952
 953 struct hostent *
 954 ht_gethostbyaddr(addr, len, af)
 955         const char *addr;
 956         int len, af;
 957 {
 958         return (_gethtbyaddr(addr, len, af));
 959 }
 960
 961 struct hostent *
 962 gethostent()
 963 {
 964         return (_gethtent());
 965 }
 966
 967 void
 968 dns_service()
 969 {
 970         return;
 971 }
 972
 973 #undef dn_skipname
 974 dn_skipname(comp_dn, eom)
 975         const u_char *comp_dn, *eom;
 976 {
 977         return (__dn_skipname(comp_dn, eom));
 978 }
 979 #endif /*old-style libc with yp junk in it*/