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                                 }
 393                                 cp += n;
 394                                 continue;
 395                         }
 396                         bcopy(cp, *hap++ = bp, n);
 397                         bp += n;
 398                         buflen -= n;
 399                         cp += n;
 400                         break;
 401                 default:
 402                         abort();
 403                 }
 404                 if (!had_error)
 405                         haveanswer++;
 406         }
 407         if (haveanswer) {
 408                 *ap = NULL;
 409                 *hap = NULL;
 410 # if defined(RESOLVSORT)
 411                 /*
 412                  * Note: we sort even if host can take only one address
 413                  * in its return structures - should give it the "best"
 414                  * address in that case, not some random one
 415                  */
 416                 if (_res.nsort && haveanswer > 1 && qtype == T_A)
 417                         addrsort(h_addr_ptrs, haveanswer);
 418 # endif /*RESOLVSORT*/
 419                 if (!host.h_name) {
 420                         n = strlen(qname) + 1;  /* for the \0 */
 421                         if (n > buflen || n >= MAXHOSTNAMELEN)
 422                                 goto no_recovery;
 423                         strcpy(bp, qname);
 424                         host.h_name = bp;
 425                         bp += n;
 426                         buflen -= n;
 427                 }
 428                 if (_res.options & RES_USE_INET6)
 429                         map_v4v6_hostent(&host, &bp, &buflen);
 430                 __set_h_errno (NETDB_SUCCESS);
 431                 return (&host);
 432         }
 433  no_recovery:
 434         __set_h_errno (NO_RECOVERY);
 435         return (NULL);
 436 }
 437
 438 struct hostent *
 439 gethostbyname(name)
 440         const char *name;
 441 {
 442         struct hostent *hp;
 443
 444         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 445                 __set_h_errno (NETDB_INTERNAL);
 446                 return (NULL);
 447        }
 448         if (_res.options & RES_USE_INET6) {
 449                 hp = gethostbyname2(name, AF_INET6);
 450                 if (hp)
 451                         return (hp);
 452         }
 453         return (gethostbyname2(name, AF_INET));
 454 }
 455
 456 struct hostent *
 457 gethostbyname2(name, af)
 458         const char *name;
 459         int af;
 460 {
 461         querybuf buf;
 462         register const char *cp;
 463         char *bp;
 464         int n, size, type, len;
 465         extern struct hostent *_gethtbyname2();
 466
 467         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 468                 __set_h_errno (NETDB_INTERNAL);
 469                 return (NULL);
 470         }
 471
 472         switch (af) {
 473         case AF_INET:
 474                 size = INADDRSZ;
 475                 type = T_A;
 476                 break;
 477         case AF_INET6:
 478                 size = IN6ADDRSZ;
 479                 type = T_AAAA;
 480                 break;
 481         default:
 482                 __set_h_errno (NETDB_INTERNAL);
 483                 __set_errno (EAFNOSUPPORT);
 484                 return (NULL);
 485         }
 486
 487         host.h_addrtype = af;
 488         host.h_length = size;
 489
 490         /*
 491          * if there aren't any dots, it could be a user-level alias.
 492          * this is also done in res_query() since we are not the only
 493          * function that looks up host names.
 494          */
 495         if (!strchr(name, '.') && (cp = __hostalias(name)))
 496                 name = cp;
 497
 498         /*
 499          * disallow names consisting only of digits/dots, unless
 500          * they end in a dot.
 501          */
 502         if (isdigit(name[0]))
 503                 for (cp = name;; ++cp) {
 504                         if (!*cp) {
 505                                 if (*--cp == '.')
 506                                         break;
 507                                 /*
 508                                  * All-numeric, no dot at the end.
 509                                  * Fake up a hostent as if we'd actually
 510                                  * done a lookup.
 511                                  */
 512                                 if (inet_pton(af, name, host_addr) <= 0) {
 513                                         __set_h_errno (HOST_NOT_FOUND);
 514                                         return (NULL);
 515                                 }
 516                                 strncpy(hostbuf, name, MAXDNAME);
 517                                 hostbuf[MAXDNAME] = '\0';
 518                                 bp = hostbuf + MAXDNAME;
 519                                 len = sizeof hostbuf - MAXDNAME;
 520                                 host.h_name = hostbuf;
 521                                 host.h_aliases = host_aliases;
 522                                 host_aliases[0] = NULL;
 523                                 h_addr_ptrs[0] = (char *)host_addr;
 524                                 h_addr_ptrs[1] = NULL;
 525                                 host.h_addr_list = h_addr_ptrs;
 526                                 if (_res.options & RES_USE_INET6)
 527                                         map_v4v6_hostent(&host, &bp, &len);
 528                                 __set_h_errno (NETDB_SUCCESS);
 529                                 return (&host);
 530                         }
 531                         if (!isdigit(*cp) && *cp != '.')
 532                                 break;
 533                }
 534         if ((isxdigit(name[0]) && strchr(name, ':') != NULL) ||
 535             name[0] == ':')
 536                 for (cp = name;; ++cp) {
 537                         if (!*cp) {
 538                                 if (*--cp == '.')
 539                                         break;
 540                                 /*
 541                                  * All-IPv6-legal, no dot at the end.
 542                                  * Fake up a hostent as if we'd actually
 543                                  * done a lookup.
 544                                  */
 545                                 if (inet_pton(af, name, host_addr) <= 0) {
 546                                         __set_h_errno (HOST_NOT_FOUND);
 547                                         return (NULL);
 548                                 }
 549                                 strncpy(hostbuf, name, MAXDNAME);
 550                                 hostbuf[MAXDNAME] = '\0';
 551                                 bp = hostbuf + MAXDNAME;
 552                                 len = sizeof hostbuf - MAXDNAME;
 553                                 host.h_name = hostbuf;
 554                                 host.h_aliases = host_aliases;
 555                                 host_aliases[0] = NULL;
 556                                 h_addr_ptrs[0] = (char *)host_addr;
 557                                 h_addr_ptrs[1] = NULL;
 558                                 host.h_addr_list = h_addr_ptrs;
 559                                 __set_h_errno (NETDB_SUCCESS);
 560                                 return (&host);
 561                         }
 562                         if (!isxdigit(*cp) && *cp != ':' && *cp != '.')
 563                                 break;
 564                 }
 565
 566         if ((n = res_search(name, C_IN, type, buf.buf, sizeof(buf.buf))) < 0) {
 567                 dprintf("res_search failed (%d)\n", n);
 568                 if (errno == ECONNREFUSED)
 569                         return (_gethtbyname2(name, af));
 570                 return (NULL);
 571         }
 572         return (getanswer(&buf, n, name, type));
 573 }
 574
 575 struct hostent *
 576 gethostbyaddr(addr, len, af)
 577         const char *addr;       /* XXX should have been def'd as u_char! */
 578         int len, af;
 579 {
 580         const u_char *uaddr = (const u_char *)addr;
 581         static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
 582         static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
 583         int n, size;
 584         querybuf buf;
 585         register struct hostent *hp;
 586         char qbuf[MAXDNAME+1], *qp;
 587 #ifdef SUNSECURITY
 588         register struct hostent *rhp;
 589         char **haddr;
 590         u_long old_options;
 591         char hname2[MAXDNAME+1];
 592 #endif /*SUNSECURITY*/
 593         extern struct hostent *_gethtbyaddr();
 594
 595         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 596                 __set_h_errno (NETDB_INTERNAL);
 597                 return (NULL);
 598         }
 599         if (af == AF_INET6 && len == IN6ADDRSZ &&
 600             (!bcmp(uaddr, mapped, sizeof mapped) ||
 601              !bcmp(uaddr, tunnelled, sizeof tunnelled))) {
 602                 /* Unmap. */
 603                 addr += sizeof mapped;
 604                 uaddr += sizeof mapped;
 605                 af = AF_INET;
 606                 len = INADDRSZ;
 607         }
 608         switch (af) {
 609         case AF_INET:
 610                 size = INADDRSZ;
 611                 break;
 612         case AF_INET6:
 613                 size = IN6ADDRSZ;
 614                 break;
 615         default:
 616                 __set_errno (EAFNOSUPPORT);
 617                 __set_h_errno (NETDB_INTERNAL);
 618                 return (NULL);
 619         }
 620         if (size != len) {
 621                 __set_errno (EINVAL);
 622                 __set_h_errno (NETDB_INTERNAL);
 623                 return (NULL);
 624         }
 625         switch (af) {
 626         case AF_INET:
 627                 (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 628                                (uaddr[3] & 0xff),
 629                                (uaddr[2] & 0xff),
 630                                (uaddr[1] & 0xff),
 631                                (uaddr[0] & 0xff));
 632                 break;
 633         case AF_INET6:
 634                 qp = qbuf;
 635                 for (n = IN6ADDRSZ - 1; n >= 0; n--) {
 636                         qp += SPRINTF((qp, "%x.%x.",
 637                                        uaddr[n] & 0xf,
 638                                        (uaddr[n] >> 4) & 0xf));
 639                 }
 640                 strcpy(qp, "ip6.int");
 641                 break;
 642         default:
 643                 abort();
 644         }
 645         n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf.buf, sizeof buf.buf);
 646         if (n < 0) {
 647                 dprintf("res_query failed (%d)\n", n);
 648                 if (errno == ECONNREFUSED)
 649                         return (_gethtbyaddr(addr, len, af));
 650                 return (NULL);
 651         }
 652         if (!(hp = getanswer(&buf, n, qbuf, T_PTR)))
 653                 return (NULL);  /* h_errno was set by getanswer() */
 654 #ifdef SUNSECURITY
 655         if (af == AF_INET) {
 656             /*
 657              * turn off search as the name should be absolute,
 658              * 'localhost' should be matched by defnames
 659              */
 660             strncpy(hname2, hp->h_name, MAXDNAME);
 661             hname2[MAXDNAME] = '\0';
 662             old_options = _res.options;
 663             _res.options &= ~RES_DNSRCH;
 664             _res.options |= RES_DEFNAMES;
 665             if (!(rhp = gethostbyname(hname2))) {
 666                 syslog(LOG_NOTICE|LOG_AUTH,
 667                        "gethostbyaddr: No A record for %s (verifying [%s])",
 668                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 669                 _res.options = old_options;
 670                 __set_h_errno (HOST_NOT_FOUND);
 671                 return (NULL);
 672             }
 673             _res.options = old_options;
 674             for (haddr = rhp->h_addr_list; *haddr; haddr++)
 675                 if (!memcmp(*haddr, addr, INADDRSZ))
 676                         break;
 677             if (!*haddr) {
 678                 syslog(LOG_NOTICE|LOG_AUTH,
 679                        "gethostbyaddr: A record of %s != PTR record [%s]",
 680                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 681                 __set_h_errno (HOST_NOT_FOUND);
 682                 return (NULL);
 683             }
 684         }
 685 #endif /*SUNSECURITY*/
 686         hp->h_addrtype = af;
 687         hp->h_length = len;
 688         bcopy(addr, host_addr, len);
 689         h_addr_ptrs[0] = (char *)host_addr;
 690         h_addr_ptrs[1] = NULL;
 691         if (af == AF_INET && (_res.options & RES_USE_INET6)) {
 692                 map_v4v6_address((char*)host_addr, (char*)host_addr);
 693                 hp->h_addrtype = AF_INET6;
 694                 hp->h_length = IN6ADDRSZ;
 695         }
 696         __set_h_errno (NETDB_SUCCESS);
 697         return (hp);
 698 }
 699
 700 void
 701 _sethtent(f)
 702         int f;
 703 {
 704         if (!hostf)
 705                 hostf = fopen(_PATH_HOSTS, "r" );
 706         else
 707                 rewind(hostf);
 708         stayopen = f;
 709 }
 710
 711 void
 712 _endhtent()
 713 {
 714         if (hostf && !stayopen) {
 715                 (void) fclose(hostf);
 716                 hostf = NULL;
 717         }
 718 }
 719
 720 struct hostent *
 721 _gethtent()
 722 {
 723         char *p;
 724         register char *cp, **q;
 725         int af, len;
 726
 727         if (!hostf && !(hostf = fopen(_PATH_HOSTS, "r" ))) {
 728                 __set_h_errno (NETDB_INTERNAL);
 729                 return (NULL);
 730         }
 731  again:
 732         if (!(p = fgets(hostbuf, sizeof hostbuf, hostf))) {
 733                 __set_h_errno (HOST_NOT_FOUND);
 734                 return (NULL);
 735         }
 736         if (*p == '#')
 737                 goto again;
 738         if (!(cp = strpbrk(p, "#\n")))
 739                 goto again;
 740         *cp = '\0';
 741         if (!(cp = strpbrk(p, " \t")))
 742                 goto again;
 743         *cp++ = '\0';
 744         if (inet_pton(AF_INET6, p, host_addr) > 0) {
 745                 af = AF_INET6;
 746                 len = IN6ADDRSZ;
 747         } else if (inet_pton(AF_INET, p, host_addr) > 0) {
 748                 if (_res.options & RES_USE_INET6) {
 749                         map_v4v6_address((char*)host_addr, (char*)host_addr);
 750                         af = AF_INET6;
 751                         len = IN6ADDRSZ;
 752                 } else {
 753                         af = AF_INET;
 754                         len = INADDRSZ;
 755                 }
 756         } else {
 757                 goto again;
 758         }
 759         h_addr_ptrs[0] = (char *)host_addr;
 760         h_addr_ptrs[1] = NULL;
 761         host.h_addr_list = h_addr_ptrs;
 762         host.h_length = len;
 763         host.h_addrtype = af;
 764         while (*cp == ' ' || *cp == '\t')
 765                 cp++;
 766         host.h_name = cp;
 767         q = host.h_aliases = host_aliases;
 768         if (cp = strpbrk(cp, " \t"))
 769                 *cp++ = '\0';
 770         while (cp && *cp) {
 771                 if (*cp == ' ' || *cp == '\t') {
 772                         cp++;
 773                         continue;
 774                 }
 775                 if (q < &host_aliases[MAXALIASES - 1])
 776                         *q++ = cp;
 777                 if (cp = strpbrk(cp, " \t"))
 778                         *cp++ = '\0';
 779         }
 780         *q = NULL;
 781         __set_h_errno (NETDB_SUCCESS);
 782         return (&host);
 783 }
 784
 785 struct hostent *
 786 _gethtbyname(name)
 787         const char *name;
 788 {
 789         extern struct hostent *_gethtbyname2();
 790         struct hostent *hp;
 791
 792         if (_res.options & RES_USE_INET6) {
 793                 hp = _gethtbyname2(name, AF_INET6);
 794                 if (hp)
 795                         return (hp);
 796         }
 797         return (_gethtbyname2(name, AF_INET));
 798 }
 799
 800 struct hostent *
 801 _gethtbyname2(name, af)
 802         const char *name;
 803         int af;
 804 {
 805         register struct hostent *p;
 806         register char **cp;
 807
 808         _sethtent(0);
 809         while (p = _gethtent()) {
 810                 if (p->h_addrtype != af)
 811                         continue;
 812                 if (strcasecmp(p->h_name, name) == 0)
 813                         break;
 814                 for (cp = p->h_aliases; *cp != 0; cp++)
 815                         if (strcasecmp(*cp, name) == 0)
 816                                 goto found;
 817         }
 818  found:
 819         _endhtent();
 820         return (p);
 821 }
 822
 823 struct hostent *
 824 _gethtbyaddr(addr, len, af)
 825         const char *addr;
 826         int len, af;
 827 {
 828         register struct hostent *p;
 829
 830         _sethtent(0);
 831         while (p = _gethtent())
 832                 if (p->h_addrtype == af && !bcmp(p->h_addr, addr, len))
 833                         break;
 834         _endhtent();
 835         return (p);
 836 }
 837
 838 static void
 839 map_v4v6_address(src, dst)
 840         const char *src;
 841         char *dst;
 842 {
 843         u_char *p = (u_char *)dst;
 844         char tmp[INADDRSZ];
 845         int i;
 846
 847         /* Stash a temporary copy so our caller can update in place. */
 848         bcopy(src, tmp, INADDRSZ);
 849         /* Mark this ipv6 addr as a mapped ipv4. */
 850         for (i = 0; i < 10; i++)
 851                 *p++ = 0x00;
 852         *p++ = 0xff;
 853         *p++ = 0xff;
 854         /* Retrieve the saved copy and we're done. */
 855         bcopy(tmp, (void*)p, INADDRSZ);
 856 }
 857
 858 static void
 859 map_v4v6_hostent(hp, bpp, lenp)
 860         struct hostent *hp;
 861         char **bpp;
 862         int *lenp;
 863 {
 864         char **ap;
 865
 866         if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
 867                 return;
 868         hp->h_addrtype = AF_INET6;
 869         hp->h_length = IN6ADDRSZ;
 870         for (ap = hp->h_addr_list; *ap; ap++) {
 871                 int i = sizeof(align) - ((u_long)*bpp % sizeof(align));
 872
 873                 if (*lenp < (i + IN6ADDRSZ)) {
 874                         /* Out of memory.  Truncate address list here.  XXX */
 875                         *ap = NULL;
 876                         return;
 877                 }
 878                 *bpp += i;
 879                 *lenp -= i;
 880                 map_v4v6_address(*ap, *bpp);
 881                 *ap = *bpp;
 882                 *bpp += IN6ADDRSZ;
 883                 *lenp -= IN6ADDRSZ;
 884         }
 885 }
 886
 887 #ifdef RESOLVSORT
 888 static void
 889 addrsort(ap, num)
 890         char **ap;
 891         int num;
 892 {
 893         int i, j;
 894         char **p;
 895         short aval[MAXADDRS];
 896         int needsort = 0;
 897
 898         p = ap;
 899         for (i = 0; i < num; i++, p++) {
 900             for (j = 0 ; (unsigned)j < _res.nsort; j++)
 901                 if (_res.sort_list[j].addr.s_addr ==
 902                     (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 903                         break;
 904             aval[i] = j;
 905             if (needsort == 0 && i > 0 && j < aval[i-1])
 906                 needsort = i;
 907         }
 908         if (!needsort)
 909             return;
 910
 911         while (needsort < num) {
 912             for (j = needsort - 1; j >= 0; j--) {
 913                 if (aval[j] > aval[j+1]) {
 914                     char *hp;
 915
 916                     i = aval[j];
 917                     aval[j] = aval[j+1];
 918                     aval[j+1] = i;
 919
 920                     hp = ap[j];
 921                     ap[j] = ap[j+1];
 922                     ap[j+1] = hp;
 923
 924                 } else
 925                     break;
 926             }
 927             needsort++;
 928         }
 929 }
 930 #endif
 931
 932 #if defined(BSD43_BSD43_NFS) || defined(sun)
 933 /* some libc's out there are bound internally to these names (UMIPS) */
 934 void
 935 ht_sethostent(stayopen)
 936         int stayopen;
 937 {
 938         _sethtent(stayopen);
 939 }
 940
 941 void
 942 ht_endhostent()
 943 {
 944         _endhtent();
 945 }
 946
 947 struct hostent *
 948 ht_gethostbyname(name)
 949         char *name;
 950 {
 951         return (_gethtbyname(name));
 952 }
 953
 954 struct hostent *
 955 ht_gethostbyaddr(addr, len, af)
 956         const char *addr;
 957         int len, af;
 958 {
 959         return (_gethtbyaddr(addr, len, af));
 960 }
 961
 962 struct hostent *
 963 gethostent()
 964 {
 965         return (_gethtent());
 966 }
 967
 968 void
 969 dns_service()
 970 {
 971         return;
 972 }
 973
 974 #undef dn_skipname
 975 dn_skipname(comp_dn, eom)
 976         const u_char *comp_dn, *eom;
 977 {
 978         return (__dn_skipname(comp_dn, eom));
 979 }
 980 #endif /*old-style libc with yp junk in it*/