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 #if defined(LIBC_SCCS) && !defined(lint)
  53 static char sccsid[] = "@(#)gethostnamadr.c     8.1 (Berkeley) 6/4/93";
  54 static char rcsid[] = "$Id$";
  55 #endif /* LIBC_SCCS and not lint */
  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 <syslog.h>
  70
  71 #define RESOLVSORT
  72
  73 #ifndef LOG_AUTH
  74 # define LOG_AUTH 0
  75 #endif
  76
  77 #define MULTI_PTRS_ARE_ALIASES 1        /* XXX - experimental */
  78
  79 #if defined(BSD) && (BSD >= 199103) && defined(AF_INET6)
  80 # include <stdlib.h>
  81 # include <string.h>
  82 #else
  83 # include "../conf/portability.h"
  84 #endif
  85
  86 #if defined(USE_OPTIONS_H)
  87 # include <../conf/options.h>
  88 #endif
  89
  90 #ifdef SPRINTF_CHAR
  91 # define SPRINTF(x) strlen(sprintf/**/x)
  92 #else
  93 # define SPRINTF(x) ((size_t)sprintf x)
  94 #endif
  95
  96 #define MAXALIASES      35
  97 #define MAXADDRS        35
  98
  99 static const char AskedForGot[] =
 100                           "gethostby*.getanswer: asked for \"%s\", got \"%s\"";
 101
 102 static char *h_addr_ptrs[MAXADDRS + 1];
 103
 104 static struct hostent host;
 105 static char *host_aliases[MAXALIASES];
 106 static char hostbuf[8*1024];
 107 static u_char host_addr[16];    /* IPv4 or IPv6 */
 108 static FILE *hostf = NULL;
 109 static int stayopen = 0;
 110
 111 static void map_v4v6_address __P((const char *src, char *dst));
 112 static void map_v4v6_hostent __P((struct hostent *hp, char **bp, int *len));
 113
 114 #ifdef RESOLVSORT
 115 extern void addrsort __P((char **, int));
 116 #endif
 117
 118 #if PACKETSZ > 65536
 119 #define MAXPACKET       PACKETSZ
 120 #else
 121 #define MAXPACKET       65536
 122 #endif
 123
 124 /* As per RFC 1034 and 1035 a host name cannot exceed 255 octets in length.  */
 125 #ifdef MAXHOSTNAMELEN
 126 # undef MAXHOSTNAMELEN
 127 #endif
 128 #define MAXHOSTNAMELEN 256
 129
 130 typedef union {
 131     HEADER hdr;
 132     u_char buf[MAXPACKET];
 133 } querybuf;
 134
 135 typedef union {
 136     int32_t al;
 137     char ac;
 138 } align;
 139
 140 #ifndef h_errno
 141 extern int h_errno;
 142 #endif
 143
 144 #ifdef DEBUG
 145 static void
 146 dprintf(msg, num)
 147         char *msg;
 148         int num;
 149 {
 150         if (_res.options & RES_DEBUG) {
 151                 int save = errno;
 152
 153                 printf(msg, num);
 154                 __set_errno (save);
 155         }
 156 }
 157 #else
 158 # define dprintf(msg, num) /*nada*/
 159 #endif
 160
 161 #define BOUNDED_INCR(x) \
 162         do { \
 163                 cp += x; \
 164                 if (cp > eom) { \
 165                         __set_h_errno (NO_RECOVERY); \
 166                         return (NULL); \
 167                 } \
 168         } while (0)
 169
 170 #define BOUNDS_CHECK(ptr, count) \
 171         do { \
 172                 if ((ptr) + (count) > eom) { \
 173                         __set_h_errno (NO_RECOVERY); \
 174                         return (NULL); \
 175                 } \
 176         } while (0)
 177
 178
 179 static struct hostent *
 180 getanswer(answer, anslen, qname, qtype)
 181         const querybuf *answer;
 182         int anslen;
 183         const char *qname;
 184         int qtype;
 185 {
 186         register const HEADER *hp;
 187         register const u_char *cp;
 188         register int n;
 189         const u_char *eom, *erdata;
 190         char *bp, **ap, **hap;
 191         int type, class, buflen, ancount, qdcount;
 192         int haveanswer, had_error;
 193         int toobig = 0;
 194         char tbuf[MAXDNAME];
 195         const char *tname;
 196         int (*name_ok) __P((const char *));
 197
 198         tname = qname;
 199         host.h_name = NULL;
 200         eom = answer->buf + anslen;
 201         switch (qtype) {
 202         case T_A:
 203         case T_AAAA:
 204                 name_ok = res_hnok;
 205                 break;
 206         case T_PTR:
 207                 name_ok = res_dnok;
 208                 break;
 209         default:
 210                 return (NULL);  /* XXX should be abort(); */
 211         }
 212         /*
 213          * find first satisfactory answer
 214          */
 215         hp = &answer->hdr;
 216         ancount = ntohs(hp->ancount);
 217         qdcount = ntohs(hp->qdcount);
 218         bp = hostbuf;
 219         buflen = sizeof hostbuf;
 220         cp = answer->buf;
 221         BOUNDED_INCR(HFIXEDSZ);
 222         if (qdcount != 1) {
 223                 __set_h_errno (NO_RECOVERY);
 224                 return (NULL);
 225         }
 226         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 227         if ((n < 0) || !(*name_ok)(bp)) {
 228                 __set_h_errno (NO_RECOVERY);
 229                 return (NULL);
 230         }
 231         BOUNDED_INCR(n + QFIXEDSZ);
 232         if (qtype == T_A || qtype == T_AAAA) {
 233                 /* res_send() has already verified that the query name is the
 234                  * same as the one we sent; this just gets the expanded name
 235                  * (i.e., with the succeeding search-domain tacked on).
 236                  */
 237                 n = strlen(bp) + 1;             /* for the \0 */
 238                 if (n >= MAXHOSTNAMELEN) {
 239                         __set_h_errno (NO_RECOVERY);
 240                         return (NULL);
 241                 }
 242                 host.h_name = bp;
 243                 bp += n;
 244                 buflen -= n;
 245                 /* The qname can be abbreviated, but h_name is now absolute. */
 246                 qname = host.h_name;
 247         }
 248         ap = host_aliases;
 249         *ap = NULL;
 250         host.h_aliases = host_aliases;
 251         hap = h_addr_ptrs;
 252         *hap = NULL;
 253         host.h_addr_list = h_addr_ptrs;
 254         haveanswer = 0;
 255         had_error = 0;
 256         while (ancount-- > 0 && cp < eom && !had_error) {
 257                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 258                 if ((n < 0) || !(*name_ok)(bp)) {
 259                         had_error++;
 260                         continue;
 261                 }
 262                 cp += n;                        /* name */
 263                 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
 264                 type = ns_get16(cp);
 265                 cp += INT16SZ;                  /* type */
 266                 class = ns_get16(cp);
 267                 cp += INT16SZ + INT32SZ;        /* class, TTL */
 268                 n = ns_get16(cp);
 269                 cp += INT16SZ;                  /* len */
 270                 BOUNDS_CHECK(cp, n);
 271                 erdata = cp + n;
 272                 if (class != C_IN) {
 273                         /* XXX - debug? syslog? */
 274                         cp += n;
 275                         continue;               /* XXX - had_error++ ? */
 276                 }
 277                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 278                         if (ap >= &host_aliases[MAXALIASES-1])
 279                                 continue;
 280                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 281                         if ((n < 0) || !(*name_ok)(tbuf)) {
 282                                 had_error++;
 283                                 continue;
 284                         }
 285                         cp += n;
 286                         if (cp != erdata) {
 287                                 __set_h_errno (NO_RECOVERY);
 288                                 return (NULL);
 289                         }
 290                         /* Store alias. */
 291                         *ap++ = bp;
 292                         n = strlen(bp) + 1;     /* for the \0 */
 293                         if (n >= MAXHOSTNAMELEN) {
 294                                 had_error++;
 295                                 continue;
 296                         }
 297                         bp += n;
 298                         buflen -= n;
 299                         /* Get canonical name. */
 300                         n = strlen(tbuf) + 1;   /* for the \0 */
 301                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 302                                 had_error++;
 303                                 continue;
 304                         }
 305                         strcpy(bp, tbuf);
 306                         host.h_name = bp;
 307                         bp += n;
 308                         buflen -= n;
 309                         continue;
 310                 }
 311                 if (qtype == T_PTR && type == T_CNAME) {
 312                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 313                         if (n < 0 || !res_dnok(tbuf)) {
 314                                 had_error++;
 315                                 continue;
 316                         }
 317                         cp += n;
 318                         if (cp != erdata) {
 319                                 __set_h_errno (NO_RECOVERY);
 320                                 return (NULL);
 321                         }
 322                         /* Get canonical name. */
 323                         n = strlen(tbuf) + 1;   /* for the \0 */
 324                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 325                                 had_error++;
 326                                 continue;
 327                         }
 328                         strcpy(bp, tbuf);
 329                         tname = bp;
 330                         bp += n;
 331                         buflen -= n;
 332                         continue;
 333                 }
 334                 if ((type == T_SIG) || (type == T_KEY) || (type == T_NXT)) {
 335                         /* We don't support DNSSEC yet.  For now, ignore
 336                          * the record and send a low priority message
 337                          * to syslog.
 338                          */
 339                         syslog(LOG_DEBUG|LOG_AUTH,
 340                "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
 341                                qname, p_class(C_IN), p_type(qtype),
 342                                p_type(type));
 343                         cp += n;
 344                         continue;
 345                 }
 346                 if (type != qtype) {
 347                         syslog(LOG_NOTICE|LOG_AUTH,
 348                "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
 349                                qname, p_class(C_IN), p_type(qtype),
 350                                p_type(type));
 351                         cp += n;
 352                         continue;               /* XXX - had_error++ ? */
 353                 }
 354                 switch (type) {
 355                 case T_PTR:
 356                         if (strcasecmp(tname, bp) != 0) {
 357                                 syslog(LOG_NOTICE|LOG_AUTH,
 358                                        AskedForGot, qname, bp);
 359                                 cp += n;
 360                                 continue;       /* XXX - had_error++ ? */
 361                         }
 362                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 363                         if ((n < 0) || !res_hnok(bp)) {
 364                                 had_error++;
 365                                 break;
 366                         }
 367 #if MULTI_PTRS_ARE_ALIASES
 368                         cp += n;
 369                         if (cp != erdata) {
 370                                 __set_h_errno (NO_RECOVERY);
 371                                 return (NULL);
 372                         }
 373                         if (!haveanswer)
 374                                 host.h_name = bp;
 375                         else if (ap < &host_aliases[MAXALIASES-1])
 376                                 *ap++ = bp;
 377                         else
 378                                 n = -1;
 379                         if (n != -1) {
 380                                 n = strlen(bp) + 1;     /* for the \0 */
 381                                 if (n >= MAXHOSTNAMELEN) {
 382                                         had_error++;
 383                                         break;
 384                                 }
 385                                 bp += n;
 386                                 buflen -= n;
 387                         }
 388                         break;
 389 #else
 390                         host.h_name = bp;
 391                         if (_res.options & RES_USE_INET6) {
 392                                 n = strlen(bp) + 1;     /* for the \0 */
 393                                 if (n >= MAXHOSTNAMELEN) {
 394                                         had_error++;
 395                                         break;
 396                                 }
 397                                 bp += n;
 398                                 buflen -= n;
 399                                 map_v4v6_hostent(&host, &bp, &buflen);
 400                         }
 401                         __set_h_errno (NETDB_SUCCESS);
 402                         return (&host);
 403 #endif
 404                 case T_A:
 405                 case T_AAAA:
 406                         if (strcasecmp(host.h_name, bp) != 0) {
 407                                 syslog(LOG_NOTICE|LOG_AUTH,
 408                                        AskedForGot, host.h_name, bp);
 409                                 cp += n;
 410                                 continue;       /* XXX - had_error++ ? */
 411                         }
 412                         if (n != host.h_length) {
 413                                 cp += n;
 414                                 continue;
 415                         }
 416                         if (!haveanswer) {
 417                                 register int nn;
 418
 419                                 host.h_name = bp;
 420                                 nn = strlen(bp) + 1;    /* for the \0 */
 421                                 bp += nn;
 422                                 buflen -= nn;
 423                         }
 424
 425                         /* XXX: when incrementing bp, we have to decrement
 426                          * buflen by the same amount --okir */
 427                         buflen -= sizeof(align) - ((u_long)bp % sizeof(align));
 428
 429                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 430
 431                         if (bp + n >= &hostbuf[sizeof hostbuf]) {
 432                                 dprintf("size (%d) too big\n", n);
 433                                 had_error++;
 434                                 continue;
 435                         }
 436                         if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
 437                                 if (!toobig++) {
 438                                         dprintf("Too many addresses (%d)\n",
 439                                                 MAXADDRS);
 440                                 }
 441                                 cp += n;
 442                                 continue;
 443                         }
 444                         memmove(*hap++ = bp, cp, n);
 445                         bp += n;
 446                         buflen -= n;
 447                         cp += n;
 448                         if (cp != erdata) {
 449                                 __set_h_errno (NO_RECOVERY);
 450                                 return (NULL);
 451                         }
 452                         break;
 453                 default:
 454                         abort();
 455                 }
 456                 if (!had_error)
 457                         haveanswer++;
 458         }
 459         if (haveanswer) {
 460                 *ap = NULL;
 461                 *hap = NULL;
 462 # if defined(RESOLVSORT)
 463                 /*
 464                  * Note: we sort even if host can take only one address
 465                  * in its return structures - should give it the "best"
 466                  * address in that case, not some random one
 467                  */
 468                 if (_res.nsort && haveanswer > 1 && qtype == T_A)
 469                         addrsort(h_addr_ptrs, haveanswer);
 470 # endif /*RESOLVSORT*/
 471                 if (!host.h_name) {
 472                         n = strlen(qname) + 1;  /* for the \0 */
 473                         if (n > buflen || n >= MAXHOSTNAMELEN)
 474                                 goto no_recovery;
 475                         strcpy(bp, qname);
 476                         host.h_name = bp;
 477                         bp += n;
 478                         buflen -= n;
 479                 }
 480                 if (_res.options & RES_USE_INET6)
 481                         map_v4v6_hostent(&host, &bp, &buflen);
 482                 __set_h_errno (NETDB_SUCCESS);
 483                 return (&host);
 484         }
 485  no_recovery:
 486         __set_h_errno (NO_RECOVERY);
 487         return (NULL);
 488 }
 489
 490 struct hostent *
 491 gethostbyname(name)
 492         const char *name;
 493 {
 494         struct hostent *hp;
 495
 496         if ((_res.options & RES_INIT) == 0 && __res_ninit(&_res) == -1) {
 497                 __set_h_errno (NETDB_INTERNAL);
 498                 return (NULL);
 499        }
 500         if (_res.options & RES_USE_INET6) {
 501                 hp = gethostbyname2(name, AF_INET6);
 502                 if (hp)
 503                         return (hp);
 504         }
 505         return (gethostbyname2(name, AF_INET));
 506 }
 507
 508 struct hostent *
 509 gethostbyname2(name, af)
 510         const char *name;
 511         int af;
 512 {
 513         querybuf buf;
 514         register const char *cp;
 515         char *bp;
 516         int n, size, type, len;
 517         extern struct hostent *_gethtbyname2();
 518
 519         if ((_res.options & RES_INIT) == 0 && __res_ninit(&_res) == -1) {
 520                 __set_h_errno (NETDB_INTERNAL);
 521                 return (NULL);
 522         }
 523
 524         switch (af) {
 525         case AF_INET:
 526                 size = INADDRSZ;
 527                 type = T_A;
 528                 break;
 529         case AF_INET6:
 530                 size = IN6ADDRSZ;
 531                 type = T_AAAA;
 532                 break;
 533         default:
 534                 __set_h_errno (NETDB_INTERNAL);
 535                 __set_errno (EAFNOSUPPORT);
 536                 return (NULL);
 537         }
 538
 539         host.h_addrtype = af;
 540         host.h_length = size;
 541
 542         /*
 543          * if there aren't any dots, it could be a user-level alias.
 544          * this is also done in res_query() since we are not the only
 545          * function that looks up host names.
 546          */
 547         if (!strchr(name, '.') && (cp = __hostalias(name)))
 548                 name = cp;
 549
 550         /*
 551          * disallow names consisting only of digits/dots, unless
 552          * they end in a dot.
 553          */
 554         if (isdigit(name[0]))
 555                 for (cp = name;; ++cp) {
 556                         if (!*cp) {
 557                                 if (*--cp == '.')
 558                                         break;
 559                                 /*
 560                                  * All-numeric, no dot at the end.
 561                                  * Fake up a hostent as if we'd actually
 562                                  * done a lookup.
 563                                  */
 564                                 if (inet_pton(af, name, host_addr) <= 0) {
 565                                         __set_h_errno (HOST_NOT_FOUND);
 566                                         return (NULL);
 567                                 }
 568                                 strncpy(hostbuf, name, MAXDNAME);
 569                                 hostbuf[MAXDNAME] = '\0';
 570                                 bp = hostbuf + MAXDNAME;
 571                                 len = sizeof hostbuf - MAXDNAME;
 572                                 host.h_name = hostbuf;
 573                                 host.h_aliases = host_aliases;
 574                                 host_aliases[0] = NULL;
 575                                 h_addr_ptrs[0] = (char *)host_addr;
 576                                 h_addr_ptrs[1] = NULL;
 577                                 host.h_addr_list = h_addr_ptrs;
 578                                 if (_res.options & RES_USE_INET6)
 579                                         map_v4v6_hostent(&host, &bp, &len);
 580                                 __set_h_errno (NETDB_SUCCESS);
 581                                 return (&host);
 582                         }
 583                         if (!isdigit(*cp) && *cp != '.')
 584                                 break;
 585                }
 586         if ((isxdigit(name[0]) && strchr(name, ':') != NULL) ||
 587             name[0] == ':')
 588                 for (cp = name;; ++cp) {
 589                         if (!*cp) {
 590                                 if (*--cp == '.')
 591                                         break;
 592                                 /*
 593                                  * All-IPv6-legal, no dot at the end.
 594                                  * Fake up a hostent as if we'd actually
 595                                  * done a lookup.
 596                                  */
 597                                 if (inet_pton(af, name, host_addr) <= 0) {
 598                                         __set_h_errno (HOST_NOT_FOUND);
 599                                         return (NULL);
 600                                 }
 601                                 strncpy(hostbuf, name, MAXDNAME);
 602                                 hostbuf[MAXDNAME] = '\0';
 603                                 bp = hostbuf + MAXDNAME;
 604                                 len = sizeof hostbuf - MAXDNAME;
 605                                 host.h_name = hostbuf;
 606                                 host.h_aliases = host_aliases;
 607                                 host_aliases[0] = NULL;
 608                                 h_addr_ptrs[0] = (char *)host_addr;
 609                                 h_addr_ptrs[1] = NULL;
 610                                 host.h_addr_list = h_addr_ptrs;
 611                                 __set_h_errno (NETDB_SUCCESS);
 612                                 return (&host);
 613                         }
 614                         if (!isxdigit(*cp) && *cp != ':' && *cp != '.')
 615                                 break;
 616                 }
 617
 618         if ((n = res_nsearch(&_res, name, C_IN, type, buf.buf, sizeof(buf.buf))) < 0) {
 619                 dprintf("res_nsearch failed (%d)\n", n);
 620                 if (errno == ECONNREFUSED)
 621                         return (_gethtbyname2(name, af));
 622                 return (NULL);
 623         }
 624         return (getanswer(&buf, n, name, type));
 625 }
 626
 627 struct hostent *
 628 gethostbyaddr(addr, len, af)
 629         const void *addr;
 630         socklen_t len;
 631         int af;
 632 {
 633         const u_char *uaddr = (const u_char *)addr;
 634         static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
 635         static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
 636         int n;
 637         socklen_t size;
 638         querybuf buf;
 639         register struct hostent *hp;
 640         char qbuf[MAXDNAME+1], *qp = NULL;
 641 #ifdef SUNSECURITY
 642         register struct hostent *rhp;
 643         char **haddr;
 644         u_long old_options;
 645         char hname2[MAXDNAME+1];
 646 #endif /*SUNSECURITY*/
 647         extern struct hostent *_gethtbyaddr();
 648
 649         if ((_res.options & RES_INIT) == 0 && __res_ninit(&_res) == -1) {
 650                 __set_h_errno (NETDB_INTERNAL);
 651                 return (NULL);
 652         }
 653         if (af == AF_INET6 && len == IN6ADDRSZ &&
 654             (!bcmp(uaddr, mapped, sizeof mapped) ||
 655              !bcmp(uaddr, tunnelled, sizeof tunnelled))) {
 656                 /* Unmap. */
 657                 addr += sizeof mapped;
 658                 uaddr += sizeof mapped;
 659                 af = AF_INET;
 660                 len = INADDRSZ;
 661         }
 662         switch (af) {
 663         case AF_INET:
 664                 size = INADDRSZ;
 665                 break;
 666         case AF_INET6:
 667                 size = IN6ADDRSZ;
 668                 break;
 669         default:
 670                 __set_errno (EAFNOSUPPORT);
 671                 __set_h_errno (NETDB_INTERNAL);
 672                 return (NULL);
 673         }
 674         if (size != len) {
 675                 __set_errno (EINVAL);
 676                 __set_h_errno (NETDB_INTERNAL);
 677                 return (NULL);
 678         }
 679         switch (af) {
 680         case AF_INET:
 681                 (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 682                                (uaddr[3] & 0xff),
 683                                (uaddr[2] & 0xff),
 684                                (uaddr[1] & 0xff),
 685                                (uaddr[0] & 0xff));
 686                 break;
 687         case AF_INET6:
 688                 qp = qbuf;
 689                 for (n = IN6ADDRSZ - 1; n >= 0; n--) {
 690                         qp += SPRINTF((qp, "%x.%x.",
 691                                        uaddr[n] & 0xf,
 692                                        (uaddr[n] >> 4) & 0xf));
 693                 }
 694                 strcpy(qp, "ip6.arpa");
 695                 break;
 696         default:
 697                 abort();
 698         }
 699         n = res_nquery(&_res, qbuf, C_IN, T_PTR, (u_char *)buf.buf, sizeof buf.buf);
 700         if (n < 0 && af == AF_INET6) {
 701                 strcpy(qp, "ip6.int");
 702                 n = res_nquery(&_res, qbuf, C_IN, T_PTR, (u_char *)buf.buf, sizeof buf.buf);
 703         }
 704         if (n < 0) {
 705                 dprintf("res_nquery failed (%d)\n", n);
 706                 if (errno == ECONNREFUSED)
 707                         return (_gethtbyaddr(addr, len, af));
 708                 return (NULL);
 709         }
 710         if (!(hp = getanswer(&buf, n, qbuf, T_PTR)))
 711                 return (NULL);  /* h_errno was set by getanswer() */
 712 #ifdef SUNSECURITY
 713         if (af == AF_INET) {
 714             /*
 715              * turn off search as the name should be absolute,
 716              * 'localhost' should be matched by defnames
 717              */
 718             strncpy(hname2, hp->h_name, MAXDNAME);
 719             hname2[MAXDNAME] = '\0';
 720             old_options = _res.options;
 721             _res.options &= ~RES_DNSRCH;
 722             _res.options |= RES_DEFNAMES;
 723             if (!(rhp = gethostbyname(hname2))) {
 724                 syslog(LOG_NOTICE|LOG_AUTH,
 725                        "gethostbyaddr: No A record for %s (verifying [%s])",
 726                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 727                 _res.options = old_options;
 728                 __set_h_errno (HOST_NOT_FOUND);
 729                 return (NULL);
 730             }
 731             _res.options = old_options;
 732             for (haddr = rhp->h_addr_list; *haddr; haddr++)
 733                 if (!memcmp(*haddr, addr, INADDRSZ))
 734                         break;
 735             if (!*haddr) {
 736                 syslog(LOG_NOTICE|LOG_AUTH,
 737                        "gethostbyaddr: A record of %s != PTR record [%s]",
 738                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 739                 __set_h_errno (HOST_NOT_FOUND);
 740                 return (NULL);
 741             }
 742         }
 743 #endif /*SUNSECURITY*/
 744         hp->h_addrtype = af;
 745         hp->h_length = len;
 746         memmove(host_addr, addr, len);
 747         h_addr_ptrs[0] = (char *)host_addr;
 748         h_addr_ptrs[1] = NULL;
 749         if (af == AF_INET && (_res.options & RES_USE_INET6)) {
 750                 map_v4v6_address((char*)host_addr, (char*)host_addr);
 751                 hp->h_addrtype = AF_INET6;
 752                 hp->h_length = IN6ADDRSZ;
 753         }
 754         __set_h_errno (NETDB_SUCCESS);
 755         return (hp);
 756 }
 757
 758 void
 759 _sethtent(f)
 760         int f;
 761 {
 762         if (!hostf)
 763                 hostf = fopen(_PATH_HOSTS, "r" );
 764         else
 765                 rewind(hostf);
 766         stayopen = f;
 767 }
 768
 769 void
 770 _endhtent()
 771 {
 772         if (hostf && !stayopen) {
 773                 (void) fclose(hostf);
 774                 hostf = NULL;
 775         }
 776 }
 777
 778 struct hostent *
 779 _gethtent()
 780 {
 781         char *p;
 782         register char *cp, **q;
 783         int af, len;
 784
 785         if (!hostf && !(hostf = fopen(_PATH_HOSTS, "r" ))) {
 786                 __set_h_errno (NETDB_INTERNAL);
 787                 return (NULL);
 788         }
 789  again:
 790         if (!(p = fgets(hostbuf, sizeof hostbuf, hostf))) {
 791                 __set_h_errno (HOST_NOT_FOUND);
 792                 return (NULL);
 793         }
 794         if (*p == '#')
 795                 goto again;
 796         if (!(cp = strpbrk(p, "#\n")))
 797                 goto again;
 798         *cp = '\0';
 799         if (!(cp = strpbrk(p, " \t")))
 800                 goto again;
 801         *cp++ = '\0';
 802         if (inet_pton(AF_INET6, p, host_addr) > 0) {
 803                 af = AF_INET6;
 804                 len = IN6ADDRSZ;
 805         } else if (inet_pton(AF_INET, p, host_addr) > 0) {
 806                 if (_res.options & RES_USE_INET6) {
 807                         map_v4v6_address((char*)host_addr, (char*)host_addr);
 808                         af = AF_INET6;
 809                         len = IN6ADDRSZ;
 810                 } else {
 811                         af = AF_INET;
 812                         len = INADDRSZ;
 813                 }
 814         } else {
 815                 goto again;
 816         }
 817         h_addr_ptrs[0] = (char *)host_addr;
 818         h_addr_ptrs[1] = NULL;
 819         host.h_addr_list = h_addr_ptrs;
 820         host.h_length = len;
 821         host.h_addrtype = af;
 822         while (*cp == ' ' || *cp == '\t')
 823                 cp++;
 824         host.h_name = cp;
 825         q = host.h_aliases = host_aliases;
 826         if ((cp = strpbrk(cp, " \t")))
 827                 *cp++ = '\0';
 828         while (cp && *cp) {
 829                 if (*cp == ' ' || *cp == '\t') {
 830                         cp++;
 831                         continue;
 832                 }
 833                 if (q < &host_aliases[MAXALIASES - 1])
 834                         *q++ = cp;
 835                 if ((cp = strpbrk(cp, " \t")))
 836                         *cp++ = '\0';
 837         }
 838         *q = NULL;
 839         __set_h_errno (NETDB_SUCCESS);
 840         return (&host);
 841 }
 842
 843 struct hostent *
 844 _gethtbyname(name)
 845         const char *name;
 846 {
 847         extern struct hostent *_gethtbyname2();
 848         struct hostent *hp;
 849
 850         if (_res.options & RES_USE_INET6) {
 851                 hp = _gethtbyname2(name, AF_INET6);
 852                 if (hp)
 853                         return (hp);
 854         }
 855         return (_gethtbyname2(name, AF_INET));
 856 }
 857
 858 struct hostent *
 859 _gethtbyname2(name, af)
 860         const char *name;
 861         int af;
 862 {
 863         register struct hostent *p;
 864         register char **cp;
 865
 866         _sethtent(0);
 867         while ((p = _gethtent())) {
 868                 if (p->h_addrtype != af)
 869                         continue;
 870                 if (strcasecmp(p->h_name, name) == 0)
 871                         break;
 872                 for (cp = p->h_aliases; *cp != 0; cp++)
 873                         if (strcasecmp(*cp, name) == 0)
 874                                 goto found;
 875         }
 876  found:
 877         _endhtent();
 878         return (p);
 879 }
 880
 881 struct hostent *
 882 _gethtbyaddr(addr, len, af)
 883         const char *addr;
 884         size_t len;
 885         int af;
 886 {
 887         register struct hostent *p;
 888
 889         _sethtent(0);
 890         while ((p = _gethtent()))
 891                 if (p->h_addrtype == af && !bcmp(p->h_addr, addr, len))
 892                         break;
 893         _endhtent();
 894         return (p);
 895 }
 896
 897 static void
 898 map_v4v6_address(src, dst)
 899         const char *src;
 900         char *dst;
 901 {
 902         u_char *p = (u_char *)dst;
 903         char tmp[INADDRSZ];
 904         int i;
 905
 906         /* Stash a temporary copy so our caller can update in place. */
 907         memcpy(tmp, src, INADDRSZ);
 908         /* Mark this ipv6 addr as a mapped ipv4. */
 909         for (i = 0; i < 10; i++)
 910                 *p++ = 0x00;
 911         *p++ = 0xff;
 912         *p++ = 0xff;
 913         /* Retrieve the saved copy and we're done. */
 914         memcpy((void*)p, tmp, INADDRSZ);
 915 }
 916
 917 static void
 918 map_v4v6_hostent(hp, bpp, lenp)
 919         struct hostent *hp;
 920         char **bpp;
 921         int *lenp;
 922 {
 923         char **ap;
 924
 925         if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
 926                 return;
 927         hp->h_addrtype = AF_INET6;
 928         hp->h_length = IN6ADDRSZ;
 929         for (ap = hp->h_addr_list; *ap; ap++) {
 930                 int i = sizeof(align) - ((u_long)*bpp % sizeof(align));
 931
 932                 if (*lenp < (i + IN6ADDRSZ)) {
 933                         /* Out of memory.  Truncate address list here.  XXX */
 934                         *ap = NULL;
 935                         return;
 936                 }
 937                 *bpp += i;
 938                 *lenp -= i;
 939                 map_v4v6_address(*ap, *bpp);
 940                 *ap = *bpp;
 941                 *bpp += IN6ADDRSZ;
 942                 *lenp -= IN6ADDRSZ;
 943         }
 944 }
 945
 946 #ifdef RESOLVSORT
 947 extern void
 948 addrsort(ap, num)
 949         char **ap;
 950         int num;
 951 {
 952         int i, j;
 953         char **p;
 954         short aval[MAXADDRS];
 955         int needsort = 0;
 956
 957         p = ap;
 958         for (i = 0; i < num; i++, p++) {
 959             for (j = 0 ; (unsigned)j < _res.nsort; j++)
 960                 if (_res.sort_list[j].addr.s_addr ==
 961                     (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 962                         break;
 963             aval[i] = j;
 964             if (needsort == 0 && i > 0 && j < aval[i-1])
 965                 needsort = i;
 966         }
 967         if (!needsort)
 968             return;
 969
 970         while (needsort < num) {
 971             for (j = needsort - 1; j >= 0; j--) {
 972                 if (aval[j] > aval[j+1]) {
 973                     char *hp;
 974
 975                     i = aval[j];
 976                     aval[j] = aval[j+1];
 977                     aval[j+1] = i;
 978
 979                     hp = ap[j];
 980                     ap[j] = ap[j+1];
 981                     ap[j+1] = hp;
 982
 983                 } else
 984                     break;
 985             }
 986             needsort++;
 987         }
 988 }
 989 #endif
 990
 991 #if defined(BSD43_BSD43_NFS) || defined(sun)
 992 /* some libc's out there are bound internally to these names (UMIPS) */
 993 void
 994 ht_sethostent(stayopen)
 995         int stayopen;
 996 {
 997         _sethtent(stayopen);
 998 }
 999
1000 void
1001 ht_endhostent()
1002 {
1003         _endhtent();
1004 }
1005
1006 struct hostent *
1007 ht_gethostbyname(name)
1008         char *name;
1009 {
1010         return (_gethtbyname(name));
1011 }
1012
1013 struct hostent *
1014 ht_gethostbyaddr(addr, len, af)
1015         const char *addr;
1016         size_t len;
1017         int af;
1018 {
1019         return (_gethtbyaddr(addr, len, af));
1020 }
1021
1022 struct hostent *
1023 gethostent()
1024 {
1025         return (_gethtent());
1026 }
1027
1028 void
1029 dns_service()
1030 {
1031         return;
1032 }
1033
1034 #undef dn_skipname
1035 dn_skipname(comp_dn, eom)
1036         const u_char *comp_dn, *eom;
1037 {
1038         return (__dn_skipname(comp_dn, eom));
1039 }
1040 #endif /*old-style libc with yp junk in it*/