libc/dns/gethnamaddr.c

   1 /*      $NetBSD: gethnamaddr.c,v 1.70 2006/03/22 00:03:51 christos Exp $        */
   2
   3 /*
   4  * ++Copyright++ 1985, 1988, 1993
   5  * -
   6  * Copyright (c) 1985, 1988, 1993
   7  *    The Regents of the University of California.  All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  * -
  33  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  34  *
  35  * Permission to use, copy, modify, and distribute this software for any
  36  * purpose with or without fee is hereby granted, provided that the above
  37  * copyright notice and this permission notice appear in all copies, and that
  38  * the name of Digital Equipment Corporation not be used in advertising or
  39  * publicity pertaining to distribution of the document or software without
  40  * specific, written prior permission.
  41  *
  42  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  43  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  44  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  45  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  46  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  47  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  48  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  49  * SOFTWARE.
  50  * -
  51  * --Copyright--
  52  */
  53
  54 #include <sys/cdefs.h>
  55 #include <sys/types.h>
  56
  57 #include <sys/param.h>
  58 #include <sys/socket.h>
  59 #include <sys/un.h>
  60 #include <netinet/in.h>
  61 #include <arpa/inet.h>
  62 #include <arpa/nameser.h>
  63 #include "NetdClientDispatch.h"
  64 #include "resolv_netid.h"
  65 #include "resolv_private.h"
  66 #include "resolv_cache.h"
  67 #include <assert.h>
  68 #include <ctype.h>
  69 #include <errno.h>
  70 #include <netdb.h>
  71 #include <stdarg.h>
  72 #include <stdio.h>
  73 #include <strings.h>
  74 #include <syslog.h>
  75 #include <unistd.h>
  76
  77 #define ALIGNBYTES (sizeof(uintptr_t) - 1)
  78 #define ALIGN(p) (((uintptr_t)(p) + ALIGNBYTES) &~ ALIGNBYTES)
  79
  80 #ifndef LOG_AUTH
  81 # define LOG_AUTH 0
  82 #endif
  83
  84 #define MULTI_PTRS_ARE_ALIASES 1        /* XXX - experimental */
  85
  86 #include "nsswitch.h"
  87 #include <stdlib.h>
  88 #include <string.h>
  89
  90 // This should be synchronized to ResponseCode.h
  91 static const int DnsProxyQueryResult = 222;
  92
  93 static const char AskedForGot[] =
  94                           "gethostby*.getanswer: asked for \"%s\", got \"%s\"";
  95
  96 #define MAXPACKET       (64*1024)
  97
  98 typedef union {
  99     HEADER hdr;
 100     u_char buf[MAXPACKET];
 101 } querybuf;
 102
 103 typedef union {
 104     int32_t al;
 105     char ac;
 106 } align;
 107
 108 #ifdef DEBUG
 109 static void dprintf(const char *, res_state, ...)
 110         __attribute__((__format__(__printf__, 1, 3)));
 111 #endif
 112 static struct hostent *getanswer(const querybuf *, int, const char *, int,
 113     res_state);
 114 static void map_v4v6_address(const char *, char *);
 115 static void map_v4v6_hostent(struct hostent *, char **, char *);
 116 static void addrsort(char **, int, res_state);
 117
 118 static void _sethtent(int);
 119 static void _endhtent(void);
 120 static struct hostent *_gethtent(void);
 121 void ht_sethostent(int);
 122 void ht_endhostent(void);
 123 struct hostent *ht_gethostbyname(char *);
 124 struct hostent *ht_gethostbyaddr(const char *, int, int);
 125 void dns_service(void);
 126 #undef dn_skipname
 127 int dn_skipname(const u_char *, const u_char *);
 128 static int _gethtbyaddr(void *, void *, va_list);
 129 static int _gethtbyname(void *, void *, va_list);
 130 static struct hostent *_gethtbyname2(const char *, int);
 131 static int _dns_gethtbyaddr(void *, void *, va_list);
 132 static int _dns_gethtbyname(void *, void *, va_list);
 133
 134 static struct hostent *gethostbyname_internal(const char *, int, res_state, unsigned, unsigned);
 135
 136 static const ns_src default_dns_files[] = {
 137         { NSSRC_FILES,  NS_SUCCESS },
 138         { NSSRC_DNS,    NS_SUCCESS },
 139         { 0, 0 }
 140 };
 141
 142
 143 #ifdef DEBUG
 144 static void
 145 dprintf(const char *msg, res_state res, ...)
 146 {
 147         assert(msg != NULL);
 148
 149         if (res->options & RES_DEBUG) {
 150                 int save = errno;
 151                 va_list ap;
 152
 153                 va_start (ap, res);
 154                 vprintf(msg, ap);
 155                 va_end (ap);
 156
 157                 errno = save;
 158         }
 159 }
 160 #else
 161 # define dprintf(msg, res, num) ((void)0) /*nada*/
 162 #endif
 163
 164 #define BOUNDED_INCR(x) \
 165         do { \
 166                 cp += (x); \
 167                 if (cp > eom) { \
 168                         h_errno = NO_RECOVERY; \
 169                         return NULL; \
 170                 } \
 171         } while (/*CONSTCOND*/0)
 172
 173 #define BOUNDS_CHECK(ptr, count) \
 174         do { \
 175                 if ((ptr) + (count) > eom) { \
 176                         h_errno = NO_RECOVERY; \
 177                         return NULL; \
 178                 } \
 179         } while (/*CONSTCOND*/0)
 180
 181 static struct hostent *
 182 getanswer(const querybuf *answer, int anslen, const char *qname, int qtype,
 183     res_state res)
 184 {
 185         const HEADER *hp;
 186         const u_char *cp;
 187         int n;
 188         const u_char *eom, *erdata;
 189         char *bp, **ap, **hap, *ep;
 190         int type, class, ancount, qdcount;
 191         int haveanswer, had_error;
 192         int toobig = 0;
 193         char tbuf[MAXDNAME];
 194         const char *tname;
 195         int (*name_ok)(const char *);
 196         res_static  rs = __res_get_static();
 197
 198         assert(answer != NULL);
 199         assert(qname != NULL);
 200
 201         tname = qname;
 202         rs->host.h_name = NULL;
 203         eom = answer->buf + anslen;
 204         switch (qtype) {
 205         case T_A:
 206         case T_AAAA:
 207                 name_ok = res_hnok;
 208                 break;
 209         case T_PTR:
 210                 name_ok = res_dnok;
 211                 break;
 212         default:
 213                 return NULL;    /* XXX should be abort(); */
 214         }
 215         /*
 216          * find first satisfactory answer
 217          */
 218         hp = &answer->hdr;
 219         ancount = ntohs(hp->ancount);
 220         qdcount = ntohs(hp->qdcount);
 221         bp = rs->hostbuf;
 222         ep = rs->hostbuf + sizeof rs->hostbuf;
 223         cp = answer->buf;
 224         BOUNDED_INCR(HFIXEDSZ);
 225         if (qdcount != 1) {
 226                 h_errno = NO_RECOVERY;
 227                 return NULL;
 228         }
 229         n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 230         if ((n < 0) || !(*name_ok)(bp)) {
 231                 h_errno = NO_RECOVERY;
 232                 return NULL;
 233         }
 234         BOUNDED_INCR(n + QFIXEDSZ);
 235         if (qtype == T_A || qtype == T_AAAA) {
 236                 /* res_send() has already verified that the query name is the
 237                  * same as the one we sent; this just gets the expanded name
 238                  * (i.e., with the succeeding search-domain tacked on).
 239                  */
 240                 n = strlen(bp) + 1;             /* for the \0 */
 241                 if (n >= MAXHOSTNAMELEN) {
 242                         h_errno = NO_RECOVERY;
 243                         return NULL;
 244                 }
 245                 rs->host.h_name = bp;
 246                 bp += n;
 247                 /* The qname can be abbreviated, but h_name is now absolute. */
 248                 qname = rs->host.h_name;
 249         }
 250         ap = rs->host_aliases;
 251         *ap = NULL;
 252         rs->host.h_aliases = rs->host_aliases;
 253         hap = rs->h_addr_ptrs;
 254         *hap = NULL;
 255         rs->host.h_addr_list = rs->h_addr_ptrs;
 256         haveanswer = 0;
 257         had_error = 0;
 258         while (ancount-- > 0 && cp < eom && !had_error) {
 259                 n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 260                 if ((n < 0) || !(*name_ok)(bp)) {
 261                         had_error++;
 262                         continue;
 263                 }
 264                 cp += n;                        /* name */
 265                 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
 266                 type = _getshort(cp);
 267                 cp += INT16SZ;                  /* type */
 268                 class = _getshort(cp);
 269                 cp += INT16SZ + INT32SZ;        /* class, TTL */
 270                 n = _getshort(cp);
 271                 cp += INT16SZ;                  /* len */
 272                 BOUNDS_CHECK(cp, n);
 273                 erdata = cp + n;
 274                 if (class != C_IN) {
 275                         /* XXX - debug? syslog? */
 276                         cp += n;
 277                         continue;               /* XXX - had_error++ ? */
 278                 }
 279                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 280                         if (ap >= &rs->host_aliases[MAXALIASES-1])
 281                                 continue;
 282                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 283                         if ((n < 0) || !(*name_ok)(tbuf)) {
 284                                 had_error++;
 285                                 continue;
 286                         }
 287                         cp += n;
 288                         if (cp != erdata) {
 289                                 h_errno = NO_RECOVERY;
 290                                 return NULL;
 291                         }
 292                         /* Store alias. */
 293                         *ap++ = bp;
 294                         n = strlen(bp) + 1;     /* for the \0 */
 295                         if (n >= MAXHOSTNAMELEN) {
 296                                 had_error++;
 297                                 continue;
 298                         }
 299                         bp += n;
 300                         /* Get canonical name. */
 301                         n = strlen(tbuf) + 1;   /* for the \0 */
 302                         if (n > ep - bp || n >= MAXHOSTNAMELEN) {
 303                                 had_error++;
 304                                 continue;
 305                         }
 306                         strlcpy(bp, tbuf, (size_t)(ep - bp));
 307                         rs->host.h_name = bp;
 308                         bp += 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                                 h_errno = NO_RECOVERY;
 320                                 return NULL;
 321                         }
 322                         /* Get canonical name. */
 323                         n = strlen(tbuf) + 1;   /* for the \0 */
 324                         if (n > ep - bp || n >= MAXHOSTNAMELEN) {
 325                                 had_error++;
 326                                 continue;
 327                         }
 328                         strlcpy(bp, tbuf, (size_t)(ep - bp));
 329                         tname = bp;
 330                         bp += n;
 331                         continue;
 332                 }
 333                 if (type != qtype) {
 334                         if (type != T_KEY && type != T_SIG)
 335                                 syslog(LOG_NOTICE|LOG_AUTH,
 336                "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
 337                                        qname, p_class(C_IN), p_type(qtype),
 338                                        p_type(type));
 339                         cp += n;
 340                         continue;               /* XXX - had_error++ ? */
 341                 }
 342                 switch (type) {
 343                 case T_PTR:
 344                         if (strcasecmp(tname, bp) != 0) {
 345                                 syslog(LOG_NOTICE|LOG_AUTH,
 346                                        AskedForGot, qname, bp);
 347                                 cp += n;
 348                                 continue;       /* XXX - had_error++ ? */
 349                         }
 350                         n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 351                         if ((n < 0) || !res_hnok(bp)) {
 352                                 had_error++;
 353                                 break;
 354                         }
 355 #if MULTI_PTRS_ARE_ALIASES
 356                         cp += n;
 357                         if (cp != erdata) {
 358                                 h_errno = NO_RECOVERY;
 359                                 return NULL;
 360                         }
 361                         if (!haveanswer)
 362                                 rs->host.h_name = bp;
 363                         else if (ap < &rs->host_aliases[MAXALIASES-1])
 364                                 *ap++ = bp;
 365                         else
 366                                 n = -1;
 367                         if (n != -1) {
 368                                 n = strlen(bp) + 1;     /* for the \0 */
 369                                 if (n >= MAXHOSTNAMELEN) {
 370                                         had_error++;
 371                                         break;
 372                                 }
 373                                 bp += n;
 374                         }
 375                         break;
 376 #else
 377                         rs->host.h_name = bp;
 378                         if (res->options & RES_USE_INET6) {
 379                                 n = strlen(bp) + 1;     /* for the \0 */
 380                                 if (n >= MAXHOSTNAMELEN) {
 381                                         had_error++;
 382                                         break;
 383                                 }
 384                                 bp += n;
 385                                 map_v4v6_hostent(&rs->host, &bp, ep);
 386                         }
 387                         h_errno = NETDB_SUCCESS;
 388                         return &rs->host;
 389 #endif
 390                 case T_A:
 391                 case T_AAAA:
 392                         if (strcasecmp(rs->host.h_name, bp) != 0) {
 393                                 syslog(LOG_NOTICE|LOG_AUTH,
 394                                        AskedForGot, rs->host.h_name, bp);
 395                                 cp += n;
 396                                 continue;       /* XXX - had_error++ ? */
 397                         }
 398                         if (n != rs->host.h_length) {
 399                                 cp += n;
 400                                 continue;
 401                         }
 402                         if (type == T_AAAA) {
 403                                 struct in6_addr in6;
 404                                 memcpy(&in6, cp, IN6ADDRSZ);
 405                                 if (IN6_IS_ADDR_V4MAPPED(&in6)) {
 406                                         cp += n;
 407                                         continue;
 408                                 }
 409                         }
 410                         if (!haveanswer) {
 411                                 int nn;
 412
 413                                 rs->host.h_name = bp;
 414                                 nn = strlen(bp) + 1;    /* for the \0 */
 415                                 bp += nn;
 416                         }
 417
 418                         bp += sizeof(align) -
 419                             (size_t)((u_long)bp % sizeof(align));
 420
 421                         if (bp + n >= &rs->hostbuf[sizeof rs->hostbuf]) {
 422                                 dprintf("size (%d) too big\n", res, n);
 423                                 had_error++;
 424                                 continue;
 425                         }
 426                         if (hap >= &rs->h_addr_ptrs[MAXADDRS-1]) {
 427                                 if (!toobig++)
 428                                         dprintf("Too many addresses (%d)\n",
 429                                                 res, MAXADDRS);
 430                                 cp += n;
 431                                 continue;
 432                         }
 433                         (void)memcpy(*hap++ = bp, cp, (size_t)n);
 434                         bp += n;
 435                         cp += n;
 436                         if (cp != erdata) {
 437                                 h_errno = NO_RECOVERY;
 438                                 return NULL;
 439                         }
 440                         break;
 441                 default:
 442                         abort();
 443                 }
 444                 if (!had_error)
 445                         haveanswer++;
 446         }
 447         if (haveanswer) {
 448                 *ap = NULL;
 449                 *hap = NULL;
 450                 /*
 451                  * Note: we sort even if host can take only one address
 452                  * in its return structures - should give it the "best"
 453                  * address in that case, not some random one
 454                  */
 455                 if (res->nsort && haveanswer > 1 && qtype == T_A)
 456                         addrsort(rs->h_addr_ptrs, haveanswer, res);
 457                 if (!rs->host.h_name) {
 458                         n = strlen(qname) + 1;  /* for the \0 */
 459                         if (n > ep - bp || n >= MAXHOSTNAMELEN)
 460                                 goto no_recovery;
 461                         strlcpy(bp, qname, (size_t)(ep - bp));
 462                         rs->host.h_name = bp;
 463                         bp += n;
 464                 }
 465                 if (res->options & RES_USE_INET6)
 466                         map_v4v6_hostent(&rs->host, &bp, ep);
 467                 h_errno = NETDB_SUCCESS;
 468                 return &rs->host;
 469         }
 470  no_recovery:
 471         h_errno = NO_RECOVERY;
 472         return NULL;
 473 }
 474
 475 int
 476 gethostbyname_r(const char *name, struct hostent *hp, char *buf, size_t buflen,
 477     struct hostent**result, int *errorp)
 478 {
 479         struct hostent *res;
 480
 481         res = gethostbyname(name);
 482         *errorp = h_errno;
 483         if (res == NULL) {
 484                 *result = NULL;
 485                 return -1;
 486         }
 487         memcpy(hp, res, sizeof *hp);
 488         *result = hp;
 489         return 0;
 490 }
 491
 492 struct hostent *
 493 gethostbyname(const char *name)
 494 {
 495         struct hostent *hp;
 496         res_state res = __res_get_state();
 497
 498         if (res == NULL)
 499                 return NULL;
 500
 501         assert(name != NULL);
 502
 503         /* try IPv6 first - if that fails do IPv4 */
 504         if (res->options & RES_USE_INET6) {
 505                 hp = gethostbyname_internal(name, AF_INET6, res, NETID_UNSET, MARK_UNSET);
 506                 if (hp) {
 507                         __res_put_state(res);
 508                         return hp;
 509                 }
 510         }
 511         hp = gethostbyname_internal(name, AF_INET, res, NETID_UNSET, MARK_UNSET);
 512         __res_put_state(res);
 513         return hp;
 514 }
 515
 516 struct hostent *
 517 gethostbyname2(const char *name, int af)
 518 {
 519         return android_gethostbynamefornet(name, af, NETID_UNSET, MARK_UNSET);
 520 }
 521
 522 struct hostent *
 523 android_gethostbynamefornet(const char *name, int af, unsigned netid, unsigned mark)
 524 {
 525         struct hostent *hp;
 526         res_state res = __res_get_state();
 527
 528         if (res == NULL)
 529                 return NULL;
 530         hp = gethostbyname_internal(name, af, res, netid, mark);
 531         __res_put_state(res);
 532         return hp;
 533 }
 534
 535
 536 static FILE* android_open_proxy()
 537 {
 538         int sock;
 539         const int one = 1;
 540         struct sockaddr_un proxy_addr;
 541
 542         sock = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
 543         if (sock < 0) {
 544                 return NULL;
 545         }
 546
 547         setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 548         memset(&proxy_addr, 0, sizeof(proxy_addr));
 549         proxy_addr.sun_family = AF_UNIX;
 550         strlcpy(proxy_addr.sun_path, "/dev/socket/dnsproxyd", sizeof(proxy_addr.sun_path));
 551         if (TEMP_FAILURE_RETRY(connect(sock,
 552                         (const struct sockaddr*) &proxy_addr,
 553                         sizeof(proxy_addr))) != 0) {
 554                 close(sock);
 555                 return NULL;
 556         }
 557
 558         return fdopen(sock, "r+");
 559 }
 560
 561 static struct hostent *
 562 android_read_hostent(FILE* proxy)
 563 {
 564         uint32_t size;
 565         char buf[4];
 566         if (fread(buf, 1, sizeof(buf), proxy) != sizeof(buf)) return NULL;
 567
 568         /* This is reading serialized data from system/netd/server/DnsProxyListener.cpp
 569          * and changes here need to be matched there */
 570         int result_code = strtol(buf, NULL, 10);
 571         if (result_code != DnsProxyQueryResult) {
 572                 fread(&size, 1, sizeof(size), proxy);
 573                 return NULL;
 574         }
 575
 576         if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
 577         size = ntohl(size);
 578         res_static rs = __res_get_static();
 579         memset(&rs->host, 0, sizeof(rs->host));
 580         char *ptr = rs->hostbuf;
 581
 582         if (fread(ptr, 1, size, proxy) != size) return NULL;
 583         ptr += size;
 584         rs->host.h_name = rs->hostbuf;
 585
 586         char **aliases = rs->host_aliases;
 587         rs->host.h_aliases = rs->host_aliases;
 588         while (1) {
 589                 if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
 590                 size = ntohl(size);
 591
 592                 if (size == 0) {
 593                         *aliases = NULL;
 594                         break;
 595                 }
 596                 if (fread(ptr, 1, size, proxy) != size) return NULL;
 597                 *aliases++ = ptr;
 598                 ptr += size;
 599         }
 600
 601         if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
 602         rs->host.h_addrtype = ntohl(size);
 603
 604         if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
 605         rs->host.h_length = ntohl(size);
 606
 607         char **addrs = rs->h_addr_ptrs;
 608         rs->host.h_addr_list = rs->h_addr_ptrs;
 609         while (1) {
 610                 if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
 611                 size = ntohl(size);
 612                 if (size == 0) {
 613                         *addrs = NULL;
 614                         break;
 615                 }
 616                 if (fread(ptr, 1, size, proxy) != size) return NULL;
 617                 *addrs++ = ptr;
 618                 ptr += size;
 619         }
 620
 621         return &rs->host;
 622 }
 623
 624
 625 static struct hostent *
 626 gethostbyname_internal_real(const char *name, int af, res_state res)
 627 {
 628         const char *cp;
 629         char *bp, *ep;
 630         int size;
 631         struct hostent *hp;
 632         res_static rs = __res_get_static();
 633
 634         static const ns_dtab dtab[] = {
 635                 NS_FILES_CB(_gethtbyname, NULL)
 636                 { NSSRC_DNS, _dns_gethtbyname, NULL },  /* force -DHESIOD */
 637                 { 0, 0, 0 }
 638         };
 639
 640         assert(name != NULL);
 641
 642         switch (af) {
 643         case AF_INET:
 644                 size = INADDRSZ;
 645                 break;
 646         case AF_INET6:
 647                 size = IN6ADDRSZ;
 648                 break;
 649         default:
 650                 h_errno = NETDB_INTERNAL;
 651                 errno = EAFNOSUPPORT;
 652                 return NULL;
 653         }
 654
 655         rs->host.h_addrtype = af;
 656         rs->host.h_length = size;
 657
 658         /*
 659          * if there aren't any dots, it could be a user-level alias.
 660          * this is also done in res_nquery() since we are not the only
 661          * function that looks up host names.
 662          */
 663         if (!strchr(name, '.') && (cp = __hostalias(name)))
 664                 name = cp;
 665
 666         /*
 667          * disallow names consisting only of digits/dots, unless
 668          * they end in a dot.
 669          */
 670         if (isdigit((u_char) name[0]))
 671                 for (cp = name;; ++cp) {
 672                         if (!*cp) {
 673                                 if (*--cp == '.')
 674                                         break;
 675                                 /*
 676                                  * All-numeric, no dot at the end.
 677                                  * Fake up a hostent as if we'd actually
 678                                  * done a lookup.
 679                                  */
 680                                 if (inet_pton(af, name,
 681                                     (char *)(void *)rs->host_addr) <= 0) {
 682                                         h_errno = HOST_NOT_FOUND;
 683                                         return NULL;
 684                                 }
 685                                 strncpy(rs->hostbuf, name, MAXDNAME);
 686                                 rs->hostbuf[MAXDNAME] = '\0';
 687                                 bp = rs->hostbuf + MAXDNAME;
 688                                 ep = rs->hostbuf + sizeof rs->hostbuf;
 689                                 rs->host.h_name = rs->hostbuf;
 690                                 rs->host.h_aliases = rs->host_aliases;
 691                                 rs->host_aliases[0] = NULL;
 692                                 rs->h_addr_ptrs[0] = (char *)(void *)rs->host_addr;
 693                                 rs->h_addr_ptrs[1] = NULL;
 694                                 rs->host.h_addr_list = rs->h_addr_ptrs;
 695                                 if (res->options & RES_USE_INET6)
 696                                         map_v4v6_hostent(&rs->host, &bp, ep);
 697                                 h_errno = NETDB_SUCCESS;
 698                                 return &rs->host;
 699                         }
 700                         if (!isdigit((u_char) *cp) && *cp != '.')
 701                                 break;
 702                 }
 703         if ((isxdigit((u_char) name[0]) && strchr(name, ':') != NULL) ||
 704             name[0] == ':')
 705                 for (cp = name;; ++cp) {
 706                         if (!*cp) {
 707                                 if (*--cp == '.')
 708                                         break;
 709                                 /*
 710                                  * All-IPv6-legal, no dot at the end.
 711                                  * Fake up a hostent as if we'd actually
 712                                  * done a lookup.
 713                                  */
 714                                 if (inet_pton(af, name,
 715                                     (char *)(void *)rs->host_addr) <= 0) {
 716                                         h_errno = HOST_NOT_FOUND;
 717                                         return NULL;
 718                                 }
 719                                 strncpy(rs->hostbuf, name, MAXDNAME);
 720                                 rs->hostbuf[MAXDNAME] = '\0';
 721                                 bp = rs->hostbuf + MAXDNAME;
 722                                 ep = rs->hostbuf + sizeof rs->hostbuf;
 723                                 rs->host.h_name = rs->hostbuf;
 724                                 rs->host.h_aliases = rs->host_aliases;
 725                                 rs->host_aliases[0] = NULL;
 726                                 rs->h_addr_ptrs[0] = (char *)(void *)rs->host_addr;
 727                                 rs->h_addr_ptrs[1] = NULL;
 728                                 rs->host.h_addr_list = rs->h_addr_ptrs;
 729                                 h_errno = NETDB_SUCCESS;
 730                                 return &rs->host;
 731                         }
 732                         if (!isxdigit((u_char) *cp) && *cp != ':' && *cp != '.')
 733                                 break;
 734                 }
 735
 736         hp = NULL;
 737         h_errno = NETDB_INTERNAL;
 738         if (nsdispatch(&hp, dtab, NSDB_HOSTS, "gethostbyname",
 739             default_dns_files, name, strlen(name), af) != NS_SUCCESS) {
 740                 return NULL;
 741         }
 742         h_errno = NETDB_SUCCESS;
 743         return hp;
 744 }
 745
 746
 747 // very similar in proxy-ness to android_getaddrinfo_proxy
 748 static struct hostent *
 749 gethostbyname_internal(const char *name, int af, res_state res, unsigned netid, unsigned mark)
 750 {
 751         const char *cache_mode = getenv("ANDROID_DNS_MODE");
 752         FILE* proxy = NULL;
 753         struct hostent *result = NULL;
 754
 755         if (cache_mode != NULL && strcmp(cache_mode, "local") == 0) {
 756                 res_setnetid(res, netid);
 757                 res_setmark(res, mark);
 758                 return gethostbyname_internal_real(name, af, res);
 759         }
 760
 761         proxy = android_open_proxy();
 762         if (proxy == NULL) goto exit;
 763
 764         netid = __netdClientDispatch.netIdForResolv(netid);
 765
 766         /* This is writing to system/netd/server/DnsProxyListener.cpp and changes
 767          * here need to be matched there */
 768         if (fprintf(proxy, "gethostbyname %u %s %d",
 769                         netid,
 770                         name == NULL ? "^" : name,
 771                         af) < 0) {
 772                 goto exit;
 773         }
 774
 775         if (fputc(0, proxy) == EOF || fflush(proxy) != 0) {
 776                 goto exit;
 777         }
 778
 779         result = android_read_hostent(proxy);
 780
 781 exit:
 782         if (proxy != NULL) {
 783                 fclose(proxy);
 784         }
 785         return result;
 786 }
 787
 788
 789 struct hostent *
 790 android_gethostbyaddrfornet_proxy(const void *addr,
 791     socklen_t len, int af, unsigned netid)
 792 {
 793         struct hostent *result = NULL;
 794         FILE* proxy = android_open_proxy();
 795
 796         if (proxy == NULL) goto exit;
 797
 798         char buf[INET6_ADDRSTRLEN];  //big enough for IPv4 and IPv6
 799         const char * addrStr = inet_ntop(af, addr, buf, sizeof(buf));
 800         if (addrStr == NULL) goto exit;
 801
 802         netid = __netdClientDispatch.netIdForResolv(netid);
 803
 804         if (fprintf(proxy, "gethostbyaddr %s %d %d %u",
 805                         addrStr, len, af, netid) < 0) {
 806                 goto exit;
 807         }
 808
 809         if (fputc(0, proxy) == EOF || fflush(proxy) != 0) {
 810                 goto exit;
 811         }
 812
 813         result = android_read_hostent(proxy);
 814 exit:
 815         if (proxy != NULL) {
 816                 fclose(proxy);
 817         }
 818         return result;
 819 }
 820
 821 struct hostent *
 822 android_gethostbyaddrfornet_real(const void *addr,
 823     socklen_t len, int af, unsigned netid, unsigned mark)
 824 {
 825         const u_char *uaddr = (const u_char *)addr;
 826         socklen_t size;
 827         struct hostent *hp;
 828         static const ns_dtab dtab[] = {
 829                 NS_FILES_CB(_gethtbyaddr, NULL)
 830                 { NSSRC_DNS, _dns_gethtbyaddr, NULL },  /* force -DHESIOD */
 831                 { 0, 0, 0 }
 832         };
 833
 834         assert(addr != NULL);
 835
 836         if (af == AF_INET6 && len == NS_IN6ADDRSZ &&
 837             (IN6_IS_ADDR_LINKLOCAL((const struct in6_addr *)addr) ||
 838              IN6_IS_ADDR_SITELOCAL((const struct in6_addr *)addr))) {
 839                 h_errno = HOST_NOT_FOUND;
 840                 return NULL;
 841         }
 842         if (af == AF_INET6 && len == NS_IN6ADDRSZ &&
 843             (IN6_IS_ADDR_V4MAPPED((const struct in6_addr *)addr) ||
 844              IN6_IS_ADDR_V4COMPAT((const struct in6_addr *)addr))) {
 845                 /* Unmap. */
 846                 uaddr += NS_IN6ADDRSZ - NS_INADDRSZ;
 847                 addr = uaddr;
 848                 af = AF_INET;
 849                 len = NS_INADDRSZ;
 850         }
 851         switch (af) {
 852         case AF_INET:
 853                 size = NS_INADDRSZ;
 854                 break;
 855         case AF_INET6:
 856                 size = NS_IN6ADDRSZ;
 857                 break;
 858         default:
 859                 errno = EAFNOSUPPORT;
 860                 h_errno = NETDB_INTERNAL;
 861                 return NULL;
 862         }
 863         if (size != len) {
 864                 errno = EINVAL;
 865                 h_errno = NETDB_INTERNAL;
 866                 return NULL;
 867         }
 868         hp = NULL;
 869         h_errno = NETDB_INTERNAL;
 870         if (nsdispatch(&hp, dtab, NSDB_HOSTS, "gethostbyaddr",
 871                 default_dns_files, uaddr, len, af, netid, mark) != NS_SUCCESS)
 872                 return NULL;
 873         h_errno = NETDB_SUCCESS;
 874         return hp;
 875 }
 876
 877 struct hostent *
 878 android_gethostbyaddrfornet(const void *addr, socklen_t len, int af, unsigned netid, unsigned mark)
 879 {
 880         const char *cache_mode = getenv("ANDROID_DNS_MODE");
 881
 882         if (cache_mode == NULL || strcmp(cache_mode, "local") != 0) {
 883                 return android_gethostbyaddrfornet_proxy(addr, len, af, netid);
 884         } else {
 885                 return android_gethostbyaddrfornet_real(addr,len, af, netid, mark);
 886         }
 887 }
 888
 889 struct hostent *
 890 gethostbyaddr(const void *addr, socklen_t len, int af)
 891 {
 892         return android_gethostbyaddrfornet(addr, len, af, NETID_UNSET, MARK_UNSET);
 893 }
 894
 895
 896 static void
 897 _sethtent(int f)
 898 {
 899     res_static  rs = __res_get_static();
 900     if (rs == NULL) return;
 901         if (!rs->hostf)
 902                 rs->hostf = fopen(_PATH_HOSTS, "re" );
 903         else
 904                 rewind(rs->hostf);
 905         rs->stayopen = f;
 906 }
 907
 908 static void
 909 _endhtent(void)
 910 {
 911     res_static  rs = __res_get_static();
 912     if (rs == NULL) return;
 913
 914         if (rs->hostf && !rs->stayopen) {
 915                 (void) fclose(rs->hostf);
 916                 rs->hostf = NULL;
 917         }
 918 }
 919
 920 static struct hostent *
 921 _gethtent(void)
 922 {
 923         char *p;
 924         char *cp, **q;
 925         int af, len;
 926         res_static  rs = __res_get_static();
 927
 928         if (!rs->hostf && !(rs->hostf = fopen(_PATH_HOSTS, "re" ))) {
 929                 h_errno = NETDB_INTERNAL;
 930                 return NULL;
 931         }
 932  again:
 933         if (!(p = fgets(rs->hostbuf, sizeof rs->hostbuf, rs->hostf))) {
 934                 h_errno = HOST_NOT_FOUND;
 935                 return NULL;
 936         }
 937         if (*p == '#')
 938                 goto again;
 939         if (!(cp = strpbrk(p, "#\n")))
 940                 goto again;
 941         *cp = '\0';
 942         if (!(cp = strpbrk(p, " \t")))
 943                 goto again;
 944         *cp++ = '\0';
 945         if (inet_pton(AF_INET6, p, (char *)(void *)rs->host_addr) > 0) {
 946                 af = AF_INET6;
 947                 len = IN6ADDRSZ;
 948         } else if (inet_pton(AF_INET, p, (char *)(void *)rs->host_addr) > 0) {
 949                 res_state res = __res_get_state();
 950                 if (res == NULL)
 951                         return NULL;
 952                 if (res->options & RES_USE_INET6) {
 953                         map_v4v6_address((char *)(void *)rs->host_addr,
 954                             (char *)(void *)rs->host_addr);
 955                         af = AF_INET6;
 956                         len = IN6ADDRSZ;
 957                 } else {
 958                         af = AF_INET;
 959                         len = INADDRSZ;
 960                 }
 961                 __res_put_state(res);
 962         } else {
 963                 goto again;
 964         }
 965         /* if this is not something we're looking for, skip it. */
 966         if (rs->host.h_addrtype != 0 && rs->host.h_addrtype != af)
 967                 goto again;
 968         if (rs->host.h_length != 0 && rs->host.h_length != len)
 969                 goto again;
 970         rs->h_addr_ptrs[0] = (char *)(void *)rs->host_addr;
 971         rs->h_addr_ptrs[1] = NULL;
 972         rs->host.h_addr_list = rs->h_addr_ptrs;
 973         rs->host.h_length = len;
 974         rs->host.h_addrtype = af;
 975         while (*cp == ' ' || *cp == '\t')
 976                 cp++;
 977         rs->host.h_name = cp;
 978         q = rs->host.h_aliases = rs->host_aliases;
 979         if ((cp = strpbrk(cp, " \t")) != NULL)
 980                 *cp++ = '\0';
 981         while (cp && *cp) {
 982                 if (*cp == ' ' || *cp == '\t') {
 983                         cp++;
 984                         continue;
 985                 }
 986                 if (q < &rs->host_aliases[MAXALIASES - 1])
 987                         *q++ = cp;
 988                 if ((cp = strpbrk(cp, " \t")) != NULL)
 989                         *cp++ = '\0';
 990         }
 991         *q = NULL;
 992         h_errno = NETDB_SUCCESS;
 993         return &rs->host;
 994 }
 995
 996 /*ARGSUSED*/
 997 int
 998 _gethtbyname(void *rv, void *cb_data, va_list ap)
 999 {
1000         struct hostent *hp;
1001         const char *name;
1002         int af;
1003
1004         assert(rv != NULL);
1005
1006         name = va_arg(ap, char *);
1007         /* NOSTRICT skip len */(void)va_arg(ap, int);
1008         af = va_arg(ap, int);
1009
1010         hp = NULL;
1011 #if 0
1012         {
1013                 res_state res = __res_get_state();
1014                 if (res == NULL)
1015                         return NS_NOTFOUND;
1016                 if (res->options & RES_USE_INET6)
1017                         hp = _gethtbyname2(name, AF_INET6);
1018                 if (hp==NULL)
1019                         hp = _gethtbyname2(name, AF_INET);
1020                 __res_put_state(res);
1021         }
1022 #else
1023         hp = _gethtbyname2(name, af);
1024 #endif
1025         *((struct hostent **)rv) = hp;
1026         if (hp == NULL) {
1027                 h_errno = HOST_NOT_FOUND;
1028                 return NS_NOTFOUND;
1029         }
1030         return NS_SUCCESS;
1031 }
1032
1033 static struct hostent *
1034 _gethtbyname2(const char *name, int af)
1035 {
1036         struct hostent *p;
1037         char *tmpbuf, *ptr, **cp;
1038         int num;
1039         size_t len;
1040         res_static rs = __res_get_static();
1041
1042         assert(name != NULL);
1043
1044         _sethtent(rs->stayopen);
1045         ptr = tmpbuf = NULL;
1046         num = 0;
1047         while ((p = _gethtent()) != NULL && num < MAXADDRS) {
1048                 if (p->h_addrtype != af)
1049                         continue;
1050                 if (strcasecmp(p->h_name, name) != 0) {
1051                         for (cp = p->h_aliases; *cp != NULL; cp++)
1052                                 if (strcasecmp(*cp, name) == 0)
1053                                         break;
1054                         if (*cp == NULL) continue;
1055                 }
1056
1057                 if (num == 0) {
1058                         size_t bufsize;
1059                         char *src;
1060
1061                         bufsize = strlen(p->h_name) + 2 +
1062                                   MAXADDRS * p->h_length +
1063                                   ALIGNBYTES;
1064                         for (cp = p->h_aliases; *cp != NULL; cp++)
1065                                 bufsize += strlen(*cp) + 1;
1066
1067                         if ((tmpbuf = malloc(bufsize)) == NULL) {
1068                                 h_errno = NETDB_INTERNAL;
1069                                 return NULL;
1070                         }
1071
1072                         ptr = tmpbuf;
1073                         src = p->h_name;
1074                         while ((*ptr++ = *src++) != '\0');
1075                         for (cp = p->h_aliases; *cp != NULL; cp++) {
1076                                 src = *cp;
1077                                 while ((*ptr++ = *src++) != '\0');
1078                         }
1079                         *ptr++ = '\0';
1080
1081                         ptr = (char *)(void *)ALIGN(ptr);
1082                 }
1083
1084                 (void)memcpy(ptr, p->h_addr_list[0], (size_t)p->h_length);
1085                 ptr += p->h_length;
1086                 num++;
1087         }
1088         _endhtent();
1089         if (num == 0) return NULL;
1090
1091         len = ptr - tmpbuf;
1092         if (len > (sizeof(rs->hostbuf) - ALIGNBYTES)) {
1093                 free(tmpbuf);
1094                 errno = ENOSPC;
1095                 h_errno = NETDB_INTERNAL;
1096                 return NULL;
1097         }
1098         ptr = memcpy((void *)ALIGN(rs->hostbuf), tmpbuf, len);
1099         free(tmpbuf);
1100
1101         rs->host.h_name = ptr;
1102         while (*ptr++);
1103
1104         cp = rs->host_aliases;
1105         while (*ptr) {
1106                 *cp++ = ptr;
1107                 while (*ptr++);
1108         }
1109         ptr++;
1110         *cp = NULL;
1111
1112         ptr = (char *)(void *)ALIGN(ptr);
1113         cp = rs->h_addr_ptrs;
1114         while (num--) {
1115                 *cp++ = ptr;
1116                 ptr += rs->host.h_length;
1117         }
1118         *cp = NULL;
1119
1120         return &rs->host;
1121 }
1122
1123 /*ARGSUSED*/
1124 static int
1125 _gethtbyaddr(void *rv, void *cb_data, va_list ap)
1126 {
1127         struct hostent *p;
1128         const unsigned char *addr;
1129         int len, af;
1130         res_static  rs = __res_get_static();
1131
1132         assert(rv != NULL);
1133
1134         addr = va_arg(ap, unsigned char *);
1135         len = va_arg(ap, int);
1136         af = va_arg(ap, int);
1137
1138         rs->host.h_length = len;
1139         rs->host.h_addrtype = af;
1140
1141         _sethtent(rs->stayopen);
1142         while ((p = _gethtent()) != NULL)
1143                 if (p->h_addrtype == af && !memcmp(p->h_addr, addr,
1144                     (size_t)len))
1145                         break;
1146         _endhtent();
1147         *((struct hostent **)rv) = p;
1148         if (p==NULL) {
1149                 h_errno = HOST_NOT_FOUND;
1150                 return NS_NOTFOUND;
1151         }
1152         return NS_SUCCESS;
1153 }
1154
1155 static void
1156 map_v4v6_address(const char *src, char *dst)
1157 {
1158         u_char *p = (u_char *)dst;
1159         char tmp[INADDRSZ];
1160         int i;
1161
1162         assert(src != NULL);
1163         assert(dst != NULL);
1164
1165         /* Stash a temporary copy so our caller can update in place. */
1166         (void)memcpy(tmp, src, INADDRSZ);
1167         /* Mark this ipv6 addr as a mapped ipv4. */
1168         for (i = 0; i < 10; i++)
1169                 *p++ = 0x00;
1170         *p++ = 0xff;
1171         *p++ = 0xff;
1172         /* Retrieve the saved copy and we're done. */
1173         (void)memcpy((void *)p, tmp, INADDRSZ);
1174 }
1175
1176 static void
1177 map_v4v6_hostent(struct hostent *hp, char **bpp, char *ep)
1178 {
1179         char **ap;
1180
1181         assert(hp != NULL);
1182         assert(bpp != NULL);
1183         assert(ep != NULL);
1184
1185         if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
1186                 return;
1187         hp->h_addrtype = AF_INET6;
1188         hp->h_length = IN6ADDRSZ;
1189         for (ap = hp->h_addr_list; *ap; ap++) {
1190                 int i = sizeof(align) - (size_t)((u_long)*bpp % sizeof(align));
1191
1192                 if (ep - *bpp < (i + IN6ADDRSZ)) {
1193                         /* Out of memory.  Truncate address list here.  XXX */
1194                         *ap = NULL;
1195                         return;
1196                 }
1197                 *bpp += i;
1198                 map_v4v6_address(*ap, *bpp);
1199                 *ap = *bpp;
1200                 *bpp += IN6ADDRSZ;
1201         }
1202 }
1203
1204 static void
1205 addrsort(char **ap, int num, res_state res)
1206 {
1207         int i, j;
1208         char **p;
1209         short aval[MAXADDRS];
1210         int needsort = 0;
1211
1212         assert(ap != NULL);
1213
1214         p = ap;
1215         for (i = 0; i < num; i++, p++) {
1216             for (j = 0 ; (unsigned)j < res->nsort; j++)
1217                 if (res->sort_list[j].addr.s_addr ==
1218                     (((struct in_addr *)(void *)(*p))->s_addr &
1219                     res->sort_list[j].mask))
1220                         break;
1221             aval[i] = j;
1222             if (needsort == 0 && i > 0 && j < aval[i-1])
1223                 needsort = i;
1224         }
1225         if (!needsort)
1226             return;
1227
1228         while (needsort < num) {
1229             for (j = needsort - 1; j >= 0; j--) {
1230                 if (aval[j] > aval[j+1]) {
1231                     char *hp;
1232
1233                     i = aval[j];
1234                     aval[j] = aval[j+1];
1235                     aval[j+1] = i;
1236
1237                     hp = ap[j];
1238                     ap[j] = ap[j+1];
1239                     ap[j+1] = hp;
1240                 } else
1241                     break;
1242             }
1243             needsort++;
1244         }
1245 }
1246
1247 struct hostent *
1248 gethostent(void)
1249 {
1250     res_static  rs = __res_get_static();
1251         rs->host.h_addrtype = 0;
1252         rs->host.h_length = 0;
1253         return _gethtent();
1254 }
1255
1256 /*ARGSUSED*/
1257 static int
1258 _dns_gethtbyname(void *rv, void *cb_data, va_list ap)
1259 {
1260         querybuf *buf;
1261         int n, type;
1262         struct hostent *hp;
1263         const char *name;
1264         int af;
1265         res_state res;
1266
1267         assert(rv != NULL);
1268
1269         name = va_arg(ap, char *);
1270         /* NOSTRICT skip len */(void)va_arg(ap, int);
1271         af = va_arg(ap, int);
1272
1273         switch (af) {
1274         case AF_INET:
1275                 type = T_A;
1276                 break;
1277         case AF_INET6:
1278                 type = T_AAAA;
1279                 break;
1280         default:
1281                 return NS_UNAVAIL;
1282         }
1283         buf = malloc(sizeof(*buf));
1284         if (buf == NULL) {
1285                 h_errno = NETDB_INTERNAL;
1286                 return NS_NOTFOUND;
1287         }
1288         res = __res_get_state();
1289         if (res == NULL) {
1290                 free(buf);
1291                 return NS_NOTFOUND;
1292         }
1293         n = res_nsearch(res, name, C_IN, type, buf->buf, sizeof(buf->buf));
1294         if (n < 0) {
1295                 free(buf);
1296                 dprintf("res_nsearch failed (%d)\n", res, n);
1297                 __res_put_state(res);
1298                 return NS_NOTFOUND;
1299         }
1300         hp = getanswer(buf, n, name, type, res);
1301         free(buf);
1302         __res_put_state(res);
1303         if (hp == NULL)
1304                 switch (h_errno) {
1305                 case HOST_NOT_FOUND:
1306                         return NS_NOTFOUND;
1307                 case TRY_AGAIN:
1308                         return NS_TRYAGAIN;
1309                 default:
1310                         return NS_UNAVAIL;
1311                 }
1312         *((struct hostent **)rv) = hp;
1313         return NS_SUCCESS;
1314 }
1315
1316 /*ARGSUSED*/
1317 static int
1318 _dns_gethtbyaddr(void *rv, void *cb_data, va_list ap)
1319 {
1320         char qbuf[MAXDNAME + 1], *qp, *ep;
1321         int n;
1322         querybuf *buf;
1323         struct hostent *hp;
1324         const unsigned char *uaddr;
1325         int len, af, advance;
1326         res_state res;
1327         unsigned netid, mark;
1328         res_static rs = __res_get_static();
1329
1330         assert(rv != NULL);
1331
1332         uaddr = va_arg(ap, unsigned char *);
1333         len = va_arg(ap, int);
1334         af = va_arg(ap, int);
1335         netid = va_arg(ap, unsigned);
1336         mark = va_arg(ap, unsigned);
1337
1338         switch (af) {
1339         case AF_INET:
1340                 (void)snprintf(qbuf, sizeof(qbuf), "%u.%u.%u.%u.in-addr.arpa",
1341                     (uaddr[3] & 0xff), (uaddr[2] & 0xff),
1342                     (uaddr[1] & 0xff), (uaddr[0] & 0xff));
1343                 break;
1344
1345         case AF_INET6:
1346                 qp = qbuf;
1347                 ep = qbuf + sizeof(qbuf) - 1;
1348                 for (n = IN6ADDRSZ - 1; n >= 0; n--) {
1349                         advance = snprintf(qp, (size_t)(ep - qp), "%x.%x.",
1350                             uaddr[n] & 0xf,
1351                             ((unsigned int)uaddr[n] >> 4) & 0xf);
1352                         if (advance > 0 && qp + advance < ep)
1353                                 qp += advance;
1354                         else {
1355                                 h_errno = NETDB_INTERNAL;
1356                                 return NS_NOTFOUND;
1357                         }
1358                 }
1359                 if (strlcat(qbuf, "ip6.arpa", sizeof(qbuf)) >= sizeof(qbuf)) {
1360                         h_errno = NETDB_INTERNAL;
1361                         return NS_NOTFOUND;
1362                 }
1363                 break;
1364         default:
1365                 abort();
1366         }
1367
1368         buf = malloc(sizeof(*buf));
1369         if (buf == NULL) {
1370                 h_errno = NETDB_INTERNAL;
1371                 return NS_NOTFOUND;
1372         }
1373         res = __res_get_state();
1374         if (res == NULL) {
1375                 free(buf);
1376                 return NS_NOTFOUND;
1377         }
1378         res_setnetid(res, netid);
1379         res_setmark(res, mark);
1380         n = res_nquery(res, qbuf, C_IN, T_PTR, buf->buf, sizeof(buf->buf));
1381         if (n < 0) {
1382                 free(buf);
1383                 dprintf("res_nquery failed (%d)\n", res, n);
1384                 __res_put_state(res);
1385                 return NS_NOTFOUND;
1386         }
1387         hp = getanswer(buf, n, qbuf, T_PTR, res);
1388         free(buf);
1389         if (hp == NULL) {
1390                 __res_put_state(res);
1391                 switch (h_errno) {
1392                 case HOST_NOT_FOUND:
1393                         return NS_NOTFOUND;
1394                 case TRY_AGAIN:
1395                         return NS_TRYAGAIN;
1396                 default:
1397                         return NS_UNAVAIL;
1398                 }
1399         }
1400         hp->h_addrtype = af;
1401         hp->h_length = len;
1402         (void)memcpy(rs->host_addr, uaddr, (size_t)len);
1403         rs->h_addr_ptrs[0] = (char *)(void *)rs->host_addr;
1404         rs->h_addr_ptrs[1] = NULL;
1405         if (af == AF_INET && (res->options & RES_USE_INET6)) {
1406                 map_v4v6_address((char *)(void *)rs->host_addr,
1407                     (char *)(void *)rs->host_addr);
1408                 hp->h_addrtype = AF_INET6;
1409                 hp->h_length = IN6ADDRSZ;
1410         }
1411
1412         __res_put_state(res);
1413         *((struct hostent **)rv) = hp;
1414         h_errno = NETDB_SUCCESS;
1415         return NS_SUCCESS;
1416 }