dns.subproj/gethnamaddr.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.1 (the "License").  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License.
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /*
  25  * ++Copyright++ 1985, 1988, 1993
  26  * -
  27  * Copyright (c) 1985, 1988, 1993
  28  *    The Regents of the University of California.  All rights reserved.
  29  *
  30  * Redistribution and use in source and binary forms, with or without
  31  * modification, are permitted provided that the following conditions
  32  * are met:
  33  * 1. Redistributions of source code must retain the above copyright
  34  *    notice, this list of conditions and the following disclaimer.
  35  * 2. Redistributions in binary form must reproduce the above copyright
  36  *    notice, this list of conditions and the following disclaimer in the
  37  *    documentation and/or other materials provided with the distribution.
  38  * 3. All advertising materials mentioning features or use of this software
  39  *    must display the following acknowledgement:
  40  *      This product includes software developed by the University of
  41  *      California, Berkeley and its contributors.
  42  * 4. Neither the name of the University nor the names of its contributors
  43  *    may be used to endorse or promote products derived from this software
  44  *    without specific prior written permission.
  45  *
  46  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  47  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  48  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  49  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  50  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  51  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  52  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  53  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  54  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  55  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  56  * SUCH DAMAGE.
  57  * -
  58  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  59  *
  60  * Permission to use, copy, modify, and distribute this software for any
  61  * purpose with or without fee is hereby granted, provided that the above
  62  * copyright notice and this permission notice appear in all copies, and that
  63  * the name of Digital Equipment Corporation not be used in advertising or
  64  * publicity pertaining to distribution of the document or software without
  65  * specific, written prior permission.
  66  *
  67  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  68  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  69  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  70  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  71  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  72  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  73  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  74  * SOFTWARE.
  75  * -
  76  * --Copyright--
  77  */
  78
  79 #if defined(LIBC_SCCS) && !defined(lint)
  80 static char sccsid[] = "@(#)gethostnamadr.c     8.1 (Berkeley) 6/4/93";
  81 static char rcsid[] = "$Id: gethnamaddr.c,v 1.9 2004/10/07 17:33:33 majka Exp $";
  82 #endif /* LIBC_SCCS and not lint */
  83
  84 #include <sys/param.h>
  85 #include <sys/socket.h>
  86 #include <netinet/in.h>
  87 #include <arpa/inet.h>
  88 #include <arpa/nameser8_compat.h>
  89
  90 #include <stdio.h>
  91 #include <stdlib.h>
  92 #include <netdb.h>
  93 #include <resolv8_compat.h>
  94 #include <ctype.h>
  95 #include <errno.h>
  96 #include <syslog.h>
  97
  98 #ifndef LOG_AUTH
  99 # define LOG_AUTH 0
 100 #endif
 101
 102 #define MULTI_PTRS_ARE_ALIASES 1        /* XXX - experimental */
 103
 104 #if defined(BSD) && (BSD >= 199103)
 105 # include <string.h>
 106 #else
 107 # include "portability.h"
 108 #endif
 109 #if defined(USE_OPTIONS_H)
 110 # include "options.h"
 111 #endif
 112
 113 #define MAXALIASES      35
 114 #define MAXADDRS        35
 115 #define MAXHOSTBUF      8*1024
 116
 117 static const char AskedForGot[] =
 118                           "gethostby*.getanswer: asked for \"%s\", got \"%s\"";
 119
 120 static char *h_addr_ptrs[MAXADDRS + 1];
 121 static struct hostent *gethostbyname_ipv4 __P((const char *));
 122
 123 static struct hostent host;
 124 static char *host_aliases[MAXALIASES];
 125 static char *hostbuf = NULL;
 126 static struct in_addr host_addr;
 127 static FILE *hostf = NULL;
 128 static int stayopen = 0;
 129
 130 #ifdef RESOLVSORT
 131 static void addrsort __P((char **, int));
 132 #endif
 133
 134 #if PACKETSZ > 1024
 135 #define MAXPACKET       PACKETSZ
 136 #else
 137 #define MAXPACKET       1024
 138 #endif
 139
 140 typedef union {
 141     HEADER hdr;
 142     u_char buf[MAXPACKET];
 143 } querybuf;
 144
 145 typedef union {
 146     int32_t al;
 147     char ac;
 148 } align;
 149
 150 extern int h_errno;
 151
 152 extern int _lu_running(void);
 153
 154 #ifdef DEBUG
 155 static void
 156 dprintf(msg, num)
 157         char *msg;
 158         int num;
 159 {
 160         if (_res.options & RES_DEBUG) {
 161                 int save = errno;
 162
 163                 printf(msg, num);
 164                 errno = save;
 165         }
 166 }
 167 #else
 168 # define dprintf(msg, num) /*nada*/
 169 #endif
 170
 171 static struct hostent *
 172 getanswer(answer, anslen, qname, qclass, qtype)
 173         const querybuf *answer;
 174         int anslen;
 175         const char *qname;
 176         int qclass, qtype;
 177 {
 178         register const HEADER *hp;
 179         register const u_char *cp;
 180         register int n;
 181         const u_char *eom;
 182         char *bp, **ap, **hap;
 183         int type, class, buflen, ancount, qdcount;
 184         int haveanswer, had_error;
 185         int toobig = 0;
 186         char tbuf[MAXDNAME+1];
 187         const char *tname;
 188
 189         if (hostbuf == NULL) {
 190                 hostbuf = malloc(MAXHOSTBUF);
 191                 if (hostbuf == NULL)
 192                         return (NULL);
 193         }
 194         buflen = MAXHOSTBUF;
 195
 196         tname = qname;
 197         host.h_name = NULL;
 198         eom = answer->buf + anslen;
 199         /*
 200          * find first satisfactory answer
 201          */
 202         hp = &answer->hdr;
 203         ancount = ntohs(hp->ancount);
 204         qdcount = ntohs(hp->qdcount);
 205         bp = hostbuf;
 206         cp = answer->buf + HFIXEDSZ;
 207         if (qdcount != 1) {
 208                 h_errno = NO_RECOVERY;
 209                 return (NULL);
 210         }
 211         if ((n = dn_expand(answer->buf, eom, cp, bp, buflen)) < 0) {
 212                 h_errno = NO_RECOVERY;
 213                 return (NULL);
 214         }
 215         cp += n + QFIXEDSZ;
 216         if (qtype == T_A) {
 217                 /* res_send() has already verified that the query name is the
 218                  * same as the one we sent; this just gets the expanded name
 219                  * (i.e., with the succeeding search-domain tacked on).
 220                  */
 221                 n = strlen(bp) + 1;             /* for the \0 */
 222                 host.h_name = bp;
 223                 bp += n;
 224                 buflen -= n;
 225                 /* The qname can be abbreviated, but h_name is now absolute. */
 226                 qname = host.h_name;
 227         }
 228         ap = host_aliases;
 229         *ap = NULL;
 230         host.h_aliases = host_aliases;
 231         hap = h_addr_ptrs;
 232         *hap = NULL;
 233 #if BSD >= 43 || defined(h_addr)        /* new-style hostent structure */
 234         host.h_addr_list = h_addr_ptrs;
 235 #endif
 236         haveanswer = 0;
 237         had_error = 0;
 238         while (ancount-- > 0 && cp < eom && !had_error) {
 239                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 240                 if (n < 0) {
 241                         had_error++;
 242                         continue;
 243                 }
 244                 cp += n;                        /* name */
 245                 type = _getshort(cp);
 246                 cp += INT16SZ;                  /* type */
 247                 class = _getshort(cp);
 248                 cp += INT16SZ + INT32SZ;        /* class, TTL */
 249                 n = _getshort(cp);
 250                 cp += INT16SZ;                  /* len */
 251                 if (class != qclass) {
 252                         /* XXX - debug? syslog? */
 253                         cp += n;
 254                         continue;               /* XXX - had_error++ ? */
 255                 }
 256                 if (qtype == T_A && type == T_CNAME) {
 257                         if (ap >= &host_aliases[MAXALIASES-1])
 258                                 continue;
 259                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 260                         if (n < 0) {
 261                                 had_error++;
 262                                 continue;
 263                         }
 264                         cp += n;
 265                         if (host.h_name && strcasecmp(host.h_name, bp) != 0) {
 266                                 syslog(LOG_NOTICE|LOG_AUTH,
 267                 "gethostby*.getanswer: asked for \"%s\", got CNAME for \"%s\"",
 268                                        host.h_name, bp);
 269                                 continue;       /* XXX - had_error++ ? */
 270                         }
 271                         /* Store alias. */
 272                         *ap++ = bp;
 273                         n = strlen(bp) + 1;     /* for the \0 */
 274                         bp += n;
 275                         buflen -= n;
 276                         /* Get canonical name. */
 277                         n = strlen(tbuf) + 1;   /* for the \0 */
 278                         if (n > buflen) {
 279                                 had_error++;
 280                                 continue;
 281                         }
 282                         strcpy(bp, tbuf);
 283                         host.h_name = bp;
 284                         bp += n;
 285                         buflen -= n;
 286                         continue;
 287                 }
 288                 if (qtype == T_PTR && type == T_CNAME) {
 289                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 290                         if (n < 0) {
 291                                 had_error++;
 292                                 continue;
 293                         }
 294                         cp += n;
 295                         /* Get canonical name. */
 296                         n = strlen(tbuf) + 1;   /* for the \0 */
 297                         if (n > buflen) {
 298                                 had_error++;
 299                                 continue;
 300                         }
 301                         strcpy(bp, tbuf);
 302                         tname = bp;
 303                         bp += n;
 304                         buflen -= n;
 305                         continue;
 306                 }
 307                 if (type != qtype) {
 308                         syslog(LOG_NOTICE|LOG_AUTH,
 309                "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
 310                                qname, p_class(qclass), p_type(qtype),
 311                                p_type(type));
 312                         cp += n;
 313                         continue;               /* XXX - had_error++ ? */
 314                 }
 315                 switch (type) {
 316                 case T_PTR:
 317                         if (strcasecmp(tname, bp) != 0) {
 318                                 syslog(LOG_NOTICE|LOG_AUTH,
 319                                        AskedForGot, qname, bp);
 320                                 cp += n;
 321                                 continue;       /* XXX - had_error++ ? */
 322                         }
 323                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 324                         if (n < 0) {
 325                                 had_error++;
 326                                 break;
 327                         }
 328 #if MULTI_PTRS_ARE_ALIASES
 329                         cp += n;
 330                         if (!haveanswer)
 331                                 host.h_name = bp;
 332                         else if (ap < &host_aliases[MAXALIASES-1])
 333                                 *ap++ = bp;
 334                         else
 335                                 n = -1;
 336                         if (n != -1) {
 337                                 n = strlen(bp) + 1;     /* for the \0 */
 338                                 bp += n;
 339                                 buflen -= n;
 340                         }
 341                         break;
 342 #else
 343                         host.h_name = bp;
 344                         h_errno = NETDB_SUCCESS;
 345                         return (&host);
 346 #endif
 347                 case T_A:
 348                         if (strcasecmp(host.h_name, bp) != 0) {
 349                                 syslog(LOG_NOTICE|LOG_AUTH,
 350                                        AskedForGot, host.h_name, bp);
 351                                 cp += n;
 352                                 continue;       /* XXX - had_error++ ? */
 353                         }
 354                         if (haveanswer) {
 355                                 if (n != host.h_length) {
 356                                         cp += n;
 357                                         continue;
 358                                 }
 359                         } else {
 360                                 register int nn;
 361
 362                                 host.h_length = n;
 363                                 host.h_addrtype = (class == C_IN)
 364                                                   ? AF_INET
 365                                                   : AF_UNSPEC;
 366                                 host.h_name = bp;
 367                                 nn = strlen(bp) + 1;    /* for the \0 */
 368                                 bp += nn;
 369                                 buflen -= nn;
 370                         }
 371
 372                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 373
 374                         if (bp + n >= &hostbuf[MAXHOSTBUF]) {
 375                                 dprintf("size (%d) too big\n", n);
 376                                 had_error++;
 377                                 continue;
 378                         }
 379                         if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
 380                                 if (!toobig++)
 381                                         dprintf("Too many addresses (%d)\n",
 382                                                 MAXADDRS);
 383                                 cp += n;
 384                                 continue;
 385                         }
 386                         bcopy(cp, *hap++ = bp, n);
 387                         bp += n;
 388                         cp += n;
 389                         break;
 390                 default:
 391                         dprintf("Impossible condition (type=%d)\n", type);
 392                         h_errno = NO_RECOVERY;
 393                         return (NULL);
 394                 } /*switch*/
 395                 if (!had_error)
 396                         haveanswer++;
 397         } /*while*/
 398         if (haveanswer) {
 399                 *ap = NULL;
 400                 *hap = NULL;
 401 # if defined(RESOLVSORT)
 402                 /*
 403                  * Note: we sort even if host can take only one address
 404                  * in its return structures - should give it the "best"
 405                  * address in that case, not some random one
 406                  */
 407                 if (_res.nsort && haveanswer > 1 &&
 408                     qclass == C_IN && qtype == T_A)
 409                         addrsort(h_addr_ptrs, haveanswer);
 410 # endif /*RESOLVSORT*/
 411 #if BSD >= 43 || defined(h_addr)        /* new-style hostent structure */
 412                 /* nothing */
 413 #else
 414                 host.h_addr = h_addr_ptrs[0];
 415 #endif /*BSD*/
 416                 if (!host.h_name) {
 417                         n = strlen(qname) + 1;  /* for the \0 */
 418                         strcpy(bp, qname);
 419                         host.h_name = bp;
 420                 }
 421                 h_errno = NETDB_SUCCESS;
 422                 return (&host);
 423         } else {
 424                 h_errno = TRY_AGAIN;
 425                 return (NULL);
 426         }
 427 }
 428
 429 struct hostent *
 430 gethostbyname(name)
 431         const char *name;
 432 {
 433 #if defined(AF_INET6) && defined(RES_TRY_INET6)
 434         struct hostent *hp;
 435
 436         if (_res.options & RES_TRY_INET6) {
 437                 hp = gethostbyname2(name, AF_INET6);
 438                 if (hp)
 439                         return (hp);
 440         }
 441 #endif
 442         return (gethostbyname2(name, AF_INET));
 443 }
 444
 445 static struct hostent *
 446 gethostbyname_ipv4(name)
 447         const char *name;
 448 {
 449         querybuf buf;
 450         register const char *cp;
 451         int n;
 452 #if !defined(__APPLE__)
 453         extern struct hostent *_gethtbyname();
 454 #endif /* !NeXT */
 455
 456         if (hostbuf == NULL)
 457         {
 458                 hostbuf = malloc(MAXHOSTBUF);
 459                 if (hostbuf == NULL) {
 460                         h_errno = NETDB_INTERNAL;
 461                         return (NULL);
 462                 }
 463         }
 464
 465         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 466                 h_errno = NETDB_INTERNAL;
 467                 return (NULL);
 468         }
 469
 470         /*
 471          * if there aren't any dots, it could be a user-level alias.
 472          * this is also done in res_query() since we are not the only
 473          * function that looks up host names.
 474          */
 475         if (!strchr(name, '.') && (cp = __hostalias(name)))
 476                 name = cp;
 477
 478         /*
 479          * disallow names consisting only of digits/dots, unless
 480          * they end in a dot.
 481          */
 482         if (isdigit(name[0]))
 483                 for (cp = name;; ++cp) {
 484                         if (!*cp) {
 485                                 if (*--cp == '.')
 486                                         break;
 487                                 /*
 488                                  * All-numeric, no dot at the end.
 489                                  * Fake up a hostent as if we'd actually
 490                                  * done a lookup.
 491                                  */
 492                                 if (!inet_aton(name, &host_addr)) {
 493                                         h_errno = HOST_NOT_FOUND;
 494                                         return (NULL);
 495                                 }
 496                                 strncpy(hostbuf, name, MAXDNAME);
 497                                 hostbuf[MAXDNAME] = '\0';
 498                                 host.h_name = hostbuf;
 499                                 host.h_aliases = host_aliases;
 500                                 host_aliases[0] = NULL;
 501                                 host.h_addrtype = AF_INET;
 502                                 host.h_length = INT32SZ;
 503                                 h_addr_ptrs[0] = (char *)&host_addr;
 504                                 h_addr_ptrs[1] = NULL;
 505 #if BSD >= 43 || defined(h_addr)        /* new-style hostent structure */
 506                                 host.h_addr_list = h_addr_ptrs;
 507 #else
 508                                 host.h_addr = h_addr_ptrs[0];
 509 #endif
 510                                 h_errno = NETDB_SUCCESS;
 511                                 return (&host);
 512                         }
 513                         if (!isdigit(*cp) && *cp != '.')
 514                                 break;
 515                 }
 516
 517         if ((n = res_search(name, C_IN, T_A, buf.buf, sizeof(buf))) < 0) {
 518                 dprintf("res_search failed (%d)\n", n);
 519 #if !defined(__APPLE__)
 520                 if (errno == ECONNREFUSED)
 521                         return (_gethtbyname(name));
 522 #endif
 523                 return (NULL);
 524         }
 525         return (getanswer(&buf, n, name, C_IN, T_A));
 526 }
 527
 528 struct hostent *
 529 gethostbyaddr(vaddr, len, type)
 530         const void *vaddr;
 531         socklen_t len;
 532         int type;
 533 {
 534         int n;
 535         querybuf buf;
 536         register struct hostent *hp;
 537         const char* addr = (const char *)vaddr;
 538         char qbuf[MAXDNAME+1];
 539 #ifdef SUNSECURITY
 540         register struct hostent *rhp;
 541         char **haddr;
 542         u_long old_options;
 543         char hname2[MAXDNAME+1];
 544 #endif /*SUNSECURITY*/
 545 #if !defined(__APPLE__)
 546         extern struct hostent *_gethtbyaddr();
 547 #endif /* !NeXT */
 548
 549         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 550                 h_errno = NETDB_INTERNAL;
 551                 return (NULL);
 552         }
 553         if (type != AF_INET) {
 554                 errno = EAFNOSUPPORT;
 555                 h_errno = NETDB_INTERNAL;
 556                 return (NULL);
 557         }
 558         (void)sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 559                 ((unsigned)addr[3] & 0xff),
 560                 ((unsigned)addr[2] & 0xff),
 561                 ((unsigned)addr[1] & 0xff),
 562                 ((unsigned)addr[0] & 0xff));
 563         n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf.buf, sizeof buf.buf);
 564         if (n < 0) {
 565                 dprintf("res_query failed (%d)\n", n);
 566 #if !defined(__APPLE__)
 567                 if (errno == ECONNREFUSED)
 568                         return (_gethtbyaddr(addr, len, type));
 569 #endif
 570                 return (NULL);
 571         }
 572         if (!(hp = getanswer(&buf, n, qbuf, C_IN, T_PTR)))
 573                 return (NULL);  /* h_errno was set by getanswer() */
 574 #ifdef SUNSECURITY
 575         /*
 576          * turn off search as the name should be absolute,
 577          * 'localhost' should be matched by defnames
 578          */
 579         strncpy(hname2, hp->h_name, MAXDNAME);
 580         hname2[MAXDNAME] = '\0';
 581         old_options = _res.options;
 582         _res.options &= ~RES_DNSRCH;
 583         _res.options |= RES_DEFNAMES;
 584         if (!(rhp = gethostbyname(hname2))) {
 585                 syslog(LOG_NOTICE|LOG_AUTH,
 586                        "gethostbyaddr: No A record for %s (verifying [%s])",
 587                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 588                 _res.options = old_options;
 589                 h_errno = HOST_NOT_FOUND;
 590                 return (NULL);
 591         }
 592         _res.options = old_options;
 593         for (haddr = rhp->h_addr_list; *haddr; haddr++)
 594                 if (!memcmp(*haddr, addr, INADDRSZ))
 595                         break;
 596         if (!*haddr) {
 597                 syslog(LOG_NOTICE|LOG_AUTH,
 598                        "gethostbyaddr: A record of %s != PTR record [%s]",
 599                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 600                 h_errno = HOST_NOT_FOUND;
 601                 return (NULL);
 602         }
 603 #endif /*SUNSECURITY*/
 604         hp->h_addrtype = type;
 605         hp->h_length = len;
 606         h_addr_ptrs[0] = (char *)&host_addr;
 607         h_addr_ptrs[1] = NULL;
 608         host_addr = *(struct in_addr *)addr;
 609         h_errno = NETDB_SUCCESS;
 610         return (hp);
 611 }
 612
 613 void
 614 _sethtent(f)
 615         int f;
 616 {
 617         if (!hostf)
 618                 hostf = fopen(_PATH_HOSTS, "r" );
 619         else
 620                 rewind(hostf);
 621         stayopen = f;
 622 }
 623
 624 void
 625 _endhtent()
 626 {
 627         if (hostf && !stayopen) {
 628                 (void) fclose(hostf);
 629                 hostf = NULL;
 630         }
 631 }
 632
 633 struct hostent *
 634 _gethtent()
 635 {
 636         char *p;
 637         register char *cp, **q;
 638
 639         if (!hostf && !(hostf = fopen(_PATH_HOSTS, "r" ))) {
 640                 h_errno = NETDB_INTERNAL;
 641                 return (NULL);
 642         }
 643         if (hostbuf == NULL) {
 644                 hostbuf = malloc(MAXHOSTBUF);
 645                 if (hostbuf == NULL) {
 646                         h_errno = NETDB_INTERNAL;
 647                         return (NULL);
 648                 }
 649         }
 650 again:
 651         if (!(p = fgets(hostbuf, MAXHOSTBUF, hostf))) {
 652                 h_errno = HOST_NOT_FOUND;
 653                 return (NULL);
 654         }
 655         if (*p == '#')
 656                 goto again;
 657         if (!(cp = strpbrk(p, "#\n")))
 658                 goto again;
 659         *cp = '\0';
 660         if (!(cp = strpbrk(p, " \t")))
 661                 goto again;
 662         *cp++ = '\0';
 663         /* THIS STUFF IS INTERNET SPECIFIC */
 664         if (!inet_aton(p, &host_addr))
 665                 goto again;
 666         h_addr_ptrs[0] = (char *)&host_addr;
 667         h_addr_ptrs[1] = NULL;
 668 #if BSD >= 43 || defined(h_addr)        /* new-style hostent structure */
 669         host.h_addr_list = h_addr_ptrs;
 670 #else
 671         host.h_addr = h_addr_ptrs[0];
 672 #endif
 673         host.h_length = INT32SZ;
 674         host.h_addrtype = AF_INET;
 675         while (*cp == ' ' || *cp == '\t')
 676                 cp++;
 677         host.h_name = cp;
 678         q = host.h_aliases = host_aliases;
 679         if ((cp = strpbrk(cp, " \t")))
 680                 *cp++ = '\0';
 681         while (cp && *cp) {
 682                 if (*cp == ' ' || *cp == '\t') {
 683                         cp++;
 684                         continue;
 685                 }
 686                 if (q < &host_aliases[MAXALIASES - 1])
 687                         *q++ = cp;
 688                 if ((cp = strpbrk(cp, " \t")))
 689                         *cp++ = '\0';
 690         }
 691         *q = NULL;
 692         h_errno = NETDB_SUCCESS;
 693         return (&host);
 694 }
 695
 696 struct hostent *
 697 _gethtbyname(name)
 698         char *name;
 699 {
 700         register struct hostent *p;
 701         register char **cp;
 702
 703         _sethtent(0);
 704         while ((p = _gethtent())) {
 705                 if (strcasecmp(p->h_name, name) == 0)
 706                         break;
 707                 for (cp = p->h_aliases; *cp != 0; cp++)
 708                         if (strcasecmp(*cp, name) == 0)
 709                                 goto found;
 710         }
 711 found:
 712         _endhtent();
 713         return (p);
 714 }
 715
 716 struct hostent *
 717 _gethtbyaddr(addr, len, type)
 718         const char *addr;
 719         int len, type;
 720 {
 721         register struct hostent *p;
 722
 723         _sethtent(0);
 724         while ((p = _gethtent()))
 725                 if (p->h_addrtype == type && !bcmp(p->h_addr, addr, len))
 726                         break;
 727         _endhtent();
 728         return (p);
 729 }
 730
 731 #ifdef RESOLVSORT
 732 static void
 733 addrsort(ap, num)
 734         char **ap;
 735         int num;
 736 {
 737         int i, j;
 738         char **p;
 739         short aval[MAXADDRS];
 740         int needsort = 0;
 741
 742         p = ap;
 743         for (i = 0; i < num; i++, p++) {
 744             for (j = 0 ; (unsigned)j < _res.nsort; j++)
 745                 if (_res.sort_list[j].addr.s_addr ==
 746                     (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 747                         break;
 748             aval[i] = j;
 749             if (needsort == 0 && i > 0 && j < aval[i-1])
 750                 needsort = i;
 751         }
 752         if (!needsort)
 753             return;
 754
 755         while (needsort < num) {
 756             for (j = needsort - 1; j >= 0; j--) {
 757                 if (aval[j] > aval[j+1]) {
 758                     char *hp;
 759
 760                     i = aval[j];
 761                     aval[j] = aval[j+1];
 762                     aval[j+1] = i;
 763
 764                     hp = ap[j];
 765                     ap[j] = ap[j+1];
 766                     ap[j+1] = hp;
 767
 768                 } else
 769                     break;
 770             }
 771             needsort++;
 772         }
 773 }
 774 #endif
 775
 776 #if defined(BSD43_BSD43_NFS) || defined(sun)
 777 /* some libc's out there are bound internally to these names (UMIPS) */
 778 void
 779 ht_sethostent(stayopen)
 780         int stayopen;
 781 {
 782         _sethtent(stayopen);
 783 }
 784
 785 void
 786 ht_endhostent()
 787 {
 788         _endhtent();
 789 }
 790
 791 struct hostent *
 792 ht_gethostbyname(name)
 793         char *name;
 794 {
 795         return (_gethtbyname(name));
 796 }
 797
 798 struct hostent *
 799 ht_gethostbyaddr(addr, len, type)
 800         const char *addr;
 801         int len, type;
 802 {
 803         return (_gethtbyaddr(addr, len, type));
 804 }
 805
 806 struct hostent *
 807 gethostent()
 808 {
 809         return (_gethtent());
 810 }
 811
 812 void
 813 dns_service()
 814 {
 815         return;
 816 }
 817
 818 #undef dn_skipname
 819 dn_skipname(comp_dn, eom)
 820         const u_char *comp_dn, *eom;
 821 {
 822         return (__dn_skipname(comp_dn, eom));
 823 }
 824 #endif /*old-style libc with yp junk in it*/