lib/libc/resolv/res_send.c

   1 /*
   2  * @(#)res_send.c       8.1 (Berkeley) 6/4/93
   3  * $Id: res_send.c,v 1.18.10.1 2008/01/27 02:06:46 marka Exp $
   4  */
   5
   6 /*
   7  * Copyright (c) 1985, 1989, 1993
   8  *    The Regents of the University of California.  All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 /*
  36  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  37  *
  38  * Permission to use, copy, modify, and distribute this software for any
  39  * purpose with or without fee is hereby granted, provided that the above
  40  * copyright notice and this permission notice appear in all copies, and that
  41  * the name of Digital Equipment Corporation not be used in advertising or
  42  * publicity pertaining to distribution of the document or software without
  43  * specific, written prior permission.
  44  *
  45  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  46  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  47  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  48  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  49  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  50  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  51  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  52  * SOFTWARE.
  53  */
  54
  55 /*
  56  * Copyright (c) 2005 by Internet Systems Consortium, Inc. ("ISC")
  57  * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
  58  *
  59  * Permission to use, copy, modify, and distribute this software for any
  60  * purpose with or without fee is hereby granted, provided that the above
  61  * copyright notice and this permission notice appear in all copies.
  62  *
  63  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  64  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  65  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  66  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  67  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  68  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  69  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  70  */
  71
  72 /*! \file
  73  * \brief
  74  * Send query to name server and wait for reply.
  75  */
  76
  77 #include "port_before.h"
  78 #ifndef USE_KQUEUE
  79 #include "fd_setsize.h"
  80 #endif
  81
  82 #ifdef _LIBC
  83 #include "namespace.h"
  84 #endif
  85 #include <sys/types.h>
  86 #include <sys/param.h>
  87 #include <sys/time.h>
  88 #include <sys/socket.h>
  89 #include <sys/uio.h>
  90
  91 #include <netinet/in.h>
  92 #include <arpa/nameser.h>
  93 #include <arpa/inet.h>
  94
  95 #include <errno.h>
  96 #include <netdb.h>
  97 #include <resolv.h>
  98 #include <signal.h>
  99 #include <stdio.h>
 100 #include <stdlib.h>
 101 #include <string.h>
 102 #include <unistd.h>
 103
 104 #include "isc/eventlib.h"
 105
 106 #include "port_after.h"
 107 #ifdef USE_KQUEUE
 108 #include <sys/event.h>
 109 #else
 110
 111 #ifdef USE_POLL
 112 #ifdef HAVE_STROPTS_H
 113 #include <stropts.h>
 114 #endif
 115 #include <poll.h>
 116 #endif /* USE_POLL */
 117 #endif
 118
 119 #ifdef _LIBC
 120 #include "un-namespace.h"
 121 #endif
 122
 123 /* Options.  Leave them on. */
 124 #define DEBUG
 125 #include "res_debug.h"
 126 #include "res_private.h"
 127
 128 #define EXT(res) ((res)->_u._ext)
 129
 130 #if !defined(USE_POLL) && !defined(USE_KQUEUE)
 131 static const int highestFD = FD_SETSIZE - 1;
 132 #endif
 133
 134 /* Forward. */
 135
 136 static int              get_salen __P((const struct sockaddr *));
 137 static struct sockaddr * get_nsaddr __P((res_state, size_t));
 138 static int              send_vc(res_state, const u_char *, int,
 139                                 u_char *, int, int *, int);
 140 static int              send_dg(res_state,
 141 #ifdef USE_KQUEUE
 142                                 int,
 143 #endif
 144                                 const u_char *, int,
 145                                 u_char *, int, int *, int, int,
 146                                 int *, int *);
 147 static void             Aerror(const res_state, FILE *, const char *, int,
 148                                const struct sockaddr *, int);
 149 static void             Perror(const res_state, FILE *, const char *, int);
 150 static int              sock_eq(struct sockaddr *, struct sockaddr *);
 151 #if defined(NEED_PSELECT) && !defined(USE_POLL) && !defined(USE_KQUEUE)
 152 static int              pselect(int, void *, void *, void *,
 153                                 struct timespec *,
 154                                 const sigset_t *);
 155 #endif
 156 void res_pquery(const res_state, const u_char *, int, FILE *);
 157
 158 static const int niflags = NI_NUMERICHOST | NI_NUMERICSERV;
 159
 160 /* Public. */
 161
 162 /*%
 163  *      looks up "ina" in _res.ns_addr_list[]
 164  *
 165  * returns:
 166  *\li   0  : not found
 167  *\li   >0 : found
 168  *
 169  * author:
 170  *\li   paul vixie, 29may94
 171  */
 172 int
 173 res_ourserver_p(const res_state statp, const struct sockaddr *sa) {
 174         const struct sockaddr_in *inp, *srv;
 175         const struct sockaddr_in6 *in6p, *srv6;
 176         int ns;
 177
 178         switch (sa->sa_family) {
 179         case AF_INET:
 180                 inp = (const struct sockaddr_in *)sa;
 181                 for (ns = 0;  ns < statp->nscount;  ns++) {
 182                         srv = (struct sockaddr_in *)get_nsaddr(statp, ns);
 183                         if (srv->sin_family == inp->sin_family &&
 184                             srv->sin_port == inp->sin_port &&
 185                             (srv->sin_addr.s_addr == INADDR_ANY ||
 186                              srv->sin_addr.s_addr == inp->sin_addr.s_addr))
 187                                 return (1);
 188                 }
 189                 break;
 190         case AF_INET6:
 191                 if (EXT(statp).ext == NULL)
 192                         break;
 193                 in6p = (const struct sockaddr_in6 *)sa;
 194                 for (ns = 0;  ns < statp->nscount;  ns++) {
 195                         srv6 = (struct sockaddr_in6 *)get_nsaddr(statp, ns);
 196                         if (srv6->sin6_family == in6p->sin6_family &&
 197                             srv6->sin6_port == in6p->sin6_port &&
 198 #ifdef HAVE_SIN6_SCOPE_ID
 199                             (srv6->sin6_scope_id == 0 ||
 200                              srv6->sin6_scope_id == in6p->sin6_scope_id) &&
 201 #endif
 202                             (IN6_IS_ADDR_UNSPECIFIED(&srv6->sin6_addr) ||
 203                              IN6_ARE_ADDR_EQUAL(&srv6->sin6_addr, &in6p->sin6_addr)))
 204                                 return (1);
 205                 }
 206                 break;
 207         default:
 208                 break;
 209         }
 210         return (0);
 211 }
 212
 213 /*%
 214  *      look for (name,type,class) in the query section of packet (buf,eom)
 215  *
 216  * requires:
 217  *\li   buf + HFIXEDSZ <= eom
 218  *
 219  * returns:
 220  *\li   -1 : format error
 221  *\li   0  : not found
 222  *\li   >0 : found
 223  *
 224  * author:
 225  *\li   paul vixie, 29may94
 226  */
 227 int
 228 res_nameinquery(const char *name, int type, int class,
 229                 const u_char *buf, const u_char *eom)
 230 {
 231         const u_char *cp = buf + HFIXEDSZ;
 232         int qdcount = ntohs(((const HEADER*)buf)->qdcount);
 233
 234         while (qdcount-- > 0) {
 235                 char tname[MAXDNAME+1];
 236                 int n, ttype, tclass;
 237
 238                 n = dn_expand(buf, eom, cp, tname, sizeof tname);
 239                 if (n < 0)
 240                         return (-1);
 241                 cp += n;
 242                 if (cp + 2 * INT16SZ > eom)
 243                         return (-1);
 244                 ttype = ns_get16(cp); cp += INT16SZ;
 245                 tclass = ns_get16(cp); cp += INT16SZ;
 246                 if (ttype == type && tclass == class &&
 247                     ns_samename(tname, name) == 1)
 248                         return (1);
 249         }
 250         return (0);
 251 }
 252
 253 /*%
 254  *      is there a 1:1 mapping of (name,type,class)
 255  *      in (buf1,eom1) and (buf2,eom2)?
 256  *
 257  * returns:
 258  *\li   -1 : format error
 259  *\li   0  : not a 1:1 mapping
 260  *\li   >0 : is a 1:1 mapping
 261  *
 262  * author:
 263  *\li   paul vixie, 29may94
 264  */
 265 int
 266 res_queriesmatch(const u_char *buf1, const u_char *eom1,
 267                  const u_char *buf2, const u_char *eom2)
 268 {
 269         const u_char *cp = buf1 + HFIXEDSZ;
 270         int qdcount = ntohs(((const HEADER*)buf1)->qdcount);
 271
 272         if (buf1 + HFIXEDSZ > eom1 || buf2 + HFIXEDSZ > eom2)
 273                 return (-1);
 274
 275         /*
 276          * Only header section present in replies to
 277          * dynamic update packets.
 278          */
 279         if ((((const HEADER *)buf1)->opcode == ns_o_update) &&
 280             (((const HEADER *)buf2)->opcode == ns_o_update))
 281                 return (1);
 282
 283         if (qdcount != ntohs(((const HEADER*)buf2)->qdcount))
 284                 return (0);
 285         while (qdcount-- > 0) {
 286                 char tname[MAXDNAME+1];
 287                 int n, ttype, tclass;
 288
 289                 n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
 290                 if (n < 0)
 291                         return (-1);
 292                 cp += n;
 293                 if (cp + 2 * INT16SZ > eom1)
 294                         return (-1);
 295                 ttype = ns_get16(cp);   cp += INT16SZ;
 296                 tclass = ns_get16(cp); cp += INT16SZ;
 297                 if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))
 298                         return (0);
 299         }
 300         return (1);
 301 }
 302
 303 int
 304 res_nsend(res_state statp,
 305           const u_char *buf, int buflen, u_char *ans, int anssiz)
 306 {
 307         int gotsomewhere, terrno, tries, v_circuit, resplen, ns, n;
 308 #ifdef USE_KQUEUE
 309         int kq;
 310 #endif
 311         char abuf[NI_MAXHOST];
 312
 313         /* No name servers or res_init() failure */
 314         if (statp->nscount == 0 || EXT(statp).ext == NULL) {
 315                 errno = ESRCH;
 316                 return (-1);
 317         }
 318         if (anssiz < HFIXEDSZ) {
 319                 errno = EINVAL;
 320                 return (-1);
 321         }
 322         DprintQ((statp->options & RES_DEBUG) || (statp->pfcode & RES_PRF_QUERY),
 323                 (stdout, ";; res_send()\n"), buf, buflen);
 324         v_circuit = (statp->options & RES_USEVC) || buflen > PACKETSZ;
 325         gotsomewhere = 0;
 326         terrno = ETIMEDOUT;
 327
 328 #ifdef USE_KQUEUE
 329         if ((kq = kqueue()) < 0) {
 330                 Perror(statp, stderr, "kqueue", errno);
 331                 return (-1);
 332         }
 333 #endif
 334
 335         /*
 336          * If the ns_addr_list in the resolver context has changed, then
 337          * invalidate our cached copy and the associated timing data.
 338          */
 339         if (EXT(statp).nscount != 0) {
 340                 int needclose = 0;
 341                 struct sockaddr_storage peer;
 342                 ISC_SOCKLEN_T peerlen;
 343
 344                 if (EXT(statp).nscount != statp->nscount)
 345                         needclose++;
 346                 else
 347                         for (ns = 0; ns < statp->nscount; ns++) {
 348                                 if (statp->nsaddr_list[ns].sin_family &&
 349                                     !sock_eq((struct sockaddr *)&statp->nsaddr_list[ns],
 350                                              (struct sockaddr *)&EXT(statp).ext->nsaddrs[ns])) {
 351                                         needclose++;
 352                                         break;
 353                                 }
 354
 355                                 if (EXT(statp).nssocks[ns] == -1)
 356                                         continue;
 357                                 peerlen = sizeof(peer);
 358 #ifndef _LIBC
 359                                 if (getsockname(EXT(statp).nssocks[ns],
 360 #else
 361                                 if (_getsockname(EXT(statp).nssocks[ns],
 362 #endif
 363                                     (struct sockaddr *)&peer, &peerlen) < 0) {
 364                                         needclose++;
 365                                         break;
 366                                 }
 367                                 if (!sock_eq((struct sockaddr *)&peer,
 368                                     get_nsaddr(statp, ns))) {
 369                                         needclose++;
 370                                         break;
 371                                 }
 372                         }
 373                 if (needclose) {
 374                         res_nclose(statp);
 375                         EXT(statp).nscount = 0;
 376                 }
 377         }
 378
 379         /*
 380          * Maybe initialize our private copy of the ns_addr_list.
 381          */
 382         if (EXT(statp).nscount == 0) {
 383                 for (ns = 0; ns < statp->nscount; ns++) {
 384                         EXT(statp).nstimes[ns] = RES_MAXTIME;
 385                         EXT(statp).nssocks[ns] = -1;
 386                         if (!statp->nsaddr_list[ns].sin_family)
 387                                 continue;
 388                         EXT(statp).ext->nsaddrs[ns].sin =
 389                                  statp->nsaddr_list[ns];
 390                 }
 391                 EXT(statp).nscount = statp->nscount;
 392         }
 393
 394         /*
 395          * Some resolvers want to even out the load on their nameservers.
 396          * Note that RES_BLAST overrides RES_ROTATE.
 397          */
 398         if ((statp->options & RES_ROTATE) != 0U &&
 399             (statp->options & RES_BLAST) == 0U) {
 400                 union res_sockaddr_union inu;
 401                 struct sockaddr_in ina;
 402                 int lastns = statp->nscount - 1;
 403                 int fd;
 404                 u_int16_t nstime;
 405
 406                 if (EXT(statp).ext != NULL)
 407                         inu = EXT(statp).ext->nsaddrs[0];
 408                 ina = statp->nsaddr_list[0];
 409                 fd = EXT(statp).nssocks[0];
 410                 nstime = EXT(statp).nstimes[0];
 411                 for (ns = 0; ns < lastns; ns++) {
 412                         if (EXT(statp).ext != NULL)
 413                                 EXT(statp).ext->nsaddrs[ns] =
 414                                         EXT(statp).ext->nsaddrs[ns + 1];
 415                         statp->nsaddr_list[ns] = statp->nsaddr_list[ns + 1];
 416                         EXT(statp).nssocks[ns] = EXT(statp).nssocks[ns + 1];
 417                         EXT(statp).nstimes[ns] = EXT(statp).nstimes[ns + 1];
 418                 }
 419                 if (EXT(statp).ext != NULL)
 420                         EXT(statp).ext->nsaddrs[lastns] = inu;
 421                 statp->nsaddr_list[lastns] = ina;
 422                 EXT(statp).nssocks[lastns] = fd;
 423                 EXT(statp).nstimes[lastns] = nstime;
 424         }
 425
 426         /*
 427          * Send request, RETRY times, or until successful.
 428          */
 429         for (tries = 0; tries < statp->retry; tries++) {
 430             for (ns = 0; ns < statp->nscount; ns++) {
 431                 struct sockaddr *nsap;
 432                 int nsaplen;
 433                 nsap = get_nsaddr(statp, ns);
 434                 nsaplen = get_salen(nsap);
 435                 statp->_flags &= ~RES_F_LASTMASK;
 436                 statp->_flags |= (ns << RES_F_LASTSHIFT);
 437  same_ns:
 438                 if (statp->qhook) {
 439                         int done = 0, loops = 0;
 440
 441                         do {
 442                                 res_sendhookact act;
 443
 444                                 act = (*statp->qhook)(&nsap, &buf, &buflen,
 445                                                       ans, anssiz, &resplen);
 446                                 switch (act) {
 447                                 case res_goahead:
 448                                         done = 1;
 449                                         break;
 450                                 case res_nextns:
 451                                         res_nclose(statp);
 452                                         goto next_ns;
 453                                 case res_done:
 454 #ifdef USE_KQUEUE
 455                                         _close(kq);
 456 #endif
 457                                         return (resplen);
 458                                 case res_modified:
 459                                         /* give the hook another try */
 460                                         if (++loops < 42) /*doug adams*/
 461                                                 break;
 462                                         /*FALLTHROUGH*/
 463                                 case res_error:
 464                                         /*FALLTHROUGH*/
 465                                 default:
 466                                         goto fail;
 467                                 }
 468                         } while (!done);
 469                 }
 470
 471                 Dprint(((statp->options & RES_DEBUG) &&
 472                         getnameinfo(nsap, nsaplen, abuf, sizeof(abuf),
 473                                     NULL, 0, niflags) == 0),
 474                        (stdout, ";; Querying server (# %d) address = %s\n",
 475                         ns + 1, abuf));
 476
 477
 478                 if (v_circuit) {
 479                         /* Use VC; at most one attempt per server. */
 480                         tries = statp->retry;
 481                         n = send_vc(statp, buf, buflen, ans, anssiz, &terrno,
 482                                     ns);
 483                         if (n < 0)
 484                                 goto fail;
 485                         if (n == 0)
 486                                 goto next_ns;
 487                         resplen = n;
 488                 } else {
 489                         /* Use datagrams. */
 490                         n = send_dg(statp,
 491 #ifdef USE_KQUEUE
 492                                 kq,
 493 #endif
 494                                 buf, buflen, ans, anssiz, &terrno,
 495                                 ns, tries, &v_circuit, &gotsomewhere);
 496                         if (n < 0)
 497                                 goto fail;
 498                         if (n == 0)
 499                                 goto next_ns;
 500                         if (v_circuit)
 501                                 goto same_ns;
 502                         resplen = n;
 503                 }
 504
 505                 Dprint((statp->options & RES_DEBUG) ||
 506                        ((statp->pfcode & RES_PRF_REPLY) &&
 507                         (statp->pfcode & RES_PRF_HEAD1)),
 508                        (stdout, ";; got answer:\n"));
 509
 510                 DprintQ((statp->options & RES_DEBUG) ||
 511                         (statp->pfcode & RES_PRF_REPLY),
 512                         (stdout, "%s", ""),
 513                         ans, (resplen > anssiz) ? anssiz : resplen);
 514
 515                 /*
 516                  * If we have temporarily opened a virtual circuit,
 517                  * or if we haven't been asked to keep a socket open,
 518                  * close the socket.
 519                  */
 520                 if ((v_circuit && (statp->options & RES_USEVC) == 0U) ||
 521                     (statp->options & RES_STAYOPEN) == 0U) {
 522                         res_nclose(statp);
 523                 }
 524                 if (statp->rhook) {
 525                         int done = 0, loops = 0;
 526
 527                         do {
 528                                 res_sendhookact act;
 529
 530                                 act = (*statp->rhook)(nsap, buf, buflen,
 531                                                       ans, anssiz, &resplen);
 532                                 switch (act) {
 533                                 case res_goahead:
 534                                 case res_done:
 535                                         done = 1;
 536                                         break;
 537                                 case res_nextns:
 538                                         res_nclose(statp);
 539                                         goto next_ns;
 540                                 case res_modified:
 541                                         /* give the hook another try */
 542                                         if (++loops < 42) /*doug adams*/
 543                                                 break;
 544                                         /*FALLTHROUGH*/
 545                                 case res_error:
 546                                         /*FALLTHROUGH*/
 547                                 default:
 548                                         goto fail;
 549                                 }
 550                         } while (!done);
 551
 552                 }
 553 #ifdef USE_KQUEUE
 554                 _close(kq);
 555 #endif
 556                 return (resplen);
 557  next_ns: ;
 558            } /*foreach ns*/
 559         } /*foreach retry*/
 560         res_nclose(statp);
 561 #ifdef USE_KQUEUE
 562         _close(kq);
 563 #endif
 564         if (!v_circuit) {
 565                 if (!gotsomewhere)
 566                         errno = ECONNREFUSED;   /*%< no nameservers found */
 567                 else
 568                         errno = ETIMEDOUT;      /*%< no answer obtained */
 569         } else
 570                 errno = terrno;
 571         return (-1);
 572  fail:
 573         res_nclose(statp);
 574         return (-1);
 575 }
 576
 577 /* Private */
 578
 579 static int
 580 get_salen(const struct sockaddr *sa)
 581 {
 582
 583 #ifdef HAVE_SA_LEN
 584         /* There are people do not set sa_len.  Be forgiving to them. */
 585         if (sa->sa_len)
 586                 return (sa->sa_len);
 587 #endif
 588
 589         if (sa->sa_family == AF_INET)
 590                 return (sizeof(struct sockaddr_in));
 591         else if (sa->sa_family == AF_INET6)
 592                 return (sizeof(struct sockaddr_in6));
 593         else
 594                 return (0);     /*%< unknown, die on connect */
 595 }
 596
 597 /*%
 598  * pick appropriate nsaddr_list for use.  see res_init() for initialization.
 599  */
 600 static struct sockaddr *
 601 get_nsaddr(res_state statp, size_t n)
 602 {
 603
 604         if (!statp->nsaddr_list[n].sin_family && EXT(statp).ext) {
 605                 /*
 606                  * - EXT(statp).ext->nsaddrs[n] holds an address that is larger
 607                  *   than struct sockaddr, and
 608                  * - user code did not update statp->nsaddr_list[n].
 609                  */
 610                 return (struct sockaddr *)(void *)&EXT(statp).ext->nsaddrs[n];
 611         } else {
 612                 /*
 613                  * - user code updated statp->nsaddr_list[n], or
 614                  * - statp->nsaddr_list[n] has the same content as
 615                  *   EXT(statp).ext->nsaddrs[n].
 616                  */
 617                 return (struct sockaddr *)(void *)&statp->nsaddr_list[n];
 618         }
 619 }
 620
 621 static int
 622 send_vc(res_state statp,
 623         const u_char *buf, int buflen, u_char *ans, int anssiz,
 624         int *terrno, int ns)
 625 {
 626         const HEADER *hp = (const HEADER *) buf;
 627         HEADER *anhp = (HEADER *) ans;
 628         struct sockaddr *nsap;
 629         int nsaplen;
 630         int truncating, connreset, resplen, n;
 631         struct iovec iov[2];
 632         u_short len;
 633         u_char *cp;
 634         void *tmp;
 635 #ifdef SO_NOSIGPIPE
 636         int on = 1;
 637 #endif
 638
 639         nsap = get_nsaddr(statp, ns);
 640         nsaplen = get_salen(nsap);
 641
 642         connreset = 0;
 643  same_ns:
 644         truncating = 0;
 645
 646         /* Are we still talking to whom we want to talk to? */
 647         if (statp->_vcsock >= 0 && (statp->_flags & RES_F_VC) != 0) {
 648                 struct sockaddr_storage peer;
 649                 ISC_SOCKLEN_T size = sizeof peer;
 650 #ifndef _LIBC
 651                 if (getpeername(statp->_vcsock,
 652 #else
 653                 if (_getpeername(statp->_vcsock,
 654 #endif
 655                                 (struct sockaddr *)&peer, &size) < 0 ||
 656                     !sock_eq((struct sockaddr *)&peer, nsap)) {
 657                         res_nclose(statp);
 658                         statp->_flags &= ~RES_F_VC;
 659                 }
 660         }
 661
 662         if (statp->_vcsock < 0 || (statp->_flags & RES_F_VC) == 0) {
 663                 if (statp->_vcsock >= 0)
 664                         res_nclose(statp);
 665 #ifndef _LIBC
 666                 statp->_vcsock = socket(nsap->sa_family, SOCK_STREAM, 0);
 667 #else
 668                 statp->_vcsock = _socket(nsap->sa_family, SOCK_STREAM, 0);
 669 #endif
 670 #if !defined(USE_POLL) && !defined(USE_KQUEUE)
 671                 if (statp->_vcsock > highestFD) {
 672                         res_nclose(statp);
 673                         errno = ENOTSOCK;
 674                 }
 675 #endif
 676                 if (statp->_vcsock < 0) {
 677                         switch (errno) {
 678                         case EPROTONOSUPPORT:
 679 #ifdef EPFNOSUPPORT
 680                         case EPFNOSUPPORT:
 681 #endif
 682                         case EAFNOSUPPORT:
 683                                 Perror(statp, stderr, "socket(vc)", errno);
 684                                 return (0);
 685                         default:
 686                                 *terrno = errno;
 687                                 Perror(statp, stderr, "socket(vc)", errno);
 688                                 return (-1);
 689                         }
 690                 }
 691 #ifdef SO_NOSIGPIPE
 692                 /*
 693                  * Disable generation of SIGPIPE when writing to a closed
 694                  * socket.  Write should return -1 and set errno to EPIPE
 695                  * instead.
 696                  *
 697                  * Push on even if setsockopt(SO_NOSIGPIPE) fails.
 698                  */
 699                 (void)_setsockopt(statp->_vcsock, SOL_SOCKET, SO_NOSIGPIPE, &on,
 700                                  sizeof(on));
 701 #endif
 702                 errno = 0;
 703 #ifndef _LIBC
 704                 if (connect(statp->_vcsock, nsap, nsaplen) < 0) {
 705 #else
 706                 if (_connect(statp->_vcsock, nsap, nsaplen) < 0) {
 707 #endif
 708                         *terrno = errno;
 709                         Aerror(statp, stderr, "connect/vc", errno, nsap,
 710                             nsaplen);
 711                         res_nclose(statp);
 712                         return (0);
 713                 }
 714                 statp->_flags |= RES_F_VC;
 715         }
 716
 717         /*
 718          * Send length & message
 719          */
 720         ns_put16((u_short)buflen, (u_char*)&len);
 721         iov[0] = evConsIovec(&len, INT16SZ);
 722         DE_CONST(buf, tmp);
 723         iov[1] = evConsIovec(tmp, buflen);
 724 #ifndef _LIBC
 725         if (writev(statp->_vcsock, iov, 2) != (INT16SZ + buflen)) {
 726 #else
 727         if (_writev(statp->_vcsock, iov, 2) != (INT16SZ + buflen)) {
 728 #endif
 729                 *terrno = errno;
 730                 Perror(statp, stderr, "write failed", errno);
 731                 res_nclose(statp);
 732                 return (0);
 733         }
 734         /*
 735          * Receive length & response
 736          */
 737  read_len:
 738         cp = ans;
 739         len = INT16SZ;
 740 #ifndef _LIBC
 741         while ((n = read(statp->_vcsock, (char *)cp, (int)len)) > 0) {
 742 #else
 743         while ((n = _read(statp->_vcsock, (char *)cp, (int)len)) > 0) {
 744 #endif
 745                 cp += n;
 746                 if ((len -= n) == 0)
 747                         break;
 748         }
 749         if (n <= 0) {
 750                 *terrno = errno;
 751                 Perror(statp, stderr, "read failed", errno);
 752                 res_nclose(statp);
 753                 /*
 754                  * A long running process might get its TCP
 755                  * connection reset if the remote server was
 756                  * restarted.  Requery the server instead of
 757                  * trying a new one.  When there is only one
 758                  * server, this means that a query might work
 759                  * instead of failing.  We only allow one reset
 760                  * per query to prevent looping.
 761                  */
 762                 if (*terrno == ECONNRESET && !connreset) {
 763                         connreset = 1;
 764                         res_nclose(statp);
 765                         goto same_ns;
 766                 }
 767                 res_nclose(statp);
 768                 return (0);
 769         }
 770         resplen = ns_get16(ans);
 771         if (resplen > anssiz) {
 772                 Dprint(statp->options & RES_DEBUG,
 773                        (stdout, ";; response truncated\n")
 774                        );
 775                 truncating = 1;
 776                 len = anssiz;
 777         } else
 778                 len = resplen;
 779         if (len < HFIXEDSZ) {
 780                 /*
 781                  * Undersized message.
 782                  */
 783                 Dprint(statp->options & RES_DEBUG,
 784                        (stdout, ";; undersized: %d\n", len));
 785                 *terrno = EMSGSIZE;
 786                 res_nclose(statp);
 787                 return (0);
 788         }
 789         cp = ans;
 790 #ifndef _LIBC
 791         while (len != 0 && (n = read(statp->_vcsock, (char *)cp, (int)len)) > 0){
 792 #else
 793         while (len != 0 && (n = _read(statp->_vcsock, (char *)cp, (int)len)) > 0){
 794 #endif
 795                 cp += n;
 796                 len -= n;
 797         }
 798         if (n <= 0) {
 799                 *terrno = errno;
 800                 Perror(statp, stderr, "read(vc)", errno);
 801                 res_nclose(statp);
 802                 return (0);
 803         }
 804         if (truncating) {
 805                 /*
 806                  * Flush rest of answer so connection stays in synch.
 807                  */
 808                 anhp->tc = 1;
 809                 len = resplen - anssiz;
 810                 while (len != 0) {
 811                         char junk[PACKETSZ];
 812
 813 #ifndef _LIBC
 814                         n = read(statp->_vcsock, junk,
 815 #else
 816                         n = _read(statp->_vcsock, junk,
 817 #endif
 818                                  (len > sizeof junk) ? sizeof junk : len);
 819                         if (n > 0)
 820                                 len -= n;
 821                         else
 822                                 break;
 823                 }
 824         }
 825         /*
 826          * If the calling applicating has bailed out of
 827          * a previous call and failed to arrange to have
 828          * the circuit closed or the server has got
 829          * itself confused, then drop the packet and
 830          * wait for the correct one.
 831          */
 832         if (hp->id != anhp->id) {
 833                 DprintQ((statp->options & RES_DEBUG) ||
 834                         (statp->pfcode & RES_PRF_REPLY),
 835                         (stdout, ";; old answer (unexpected):\n"),
 836                         ans, (resplen > anssiz) ? anssiz: resplen);
 837                 goto read_len;
 838         }
 839
 840         /*
 841          * All is well, or the error is fatal.  Signal that the
 842          * next nameserver ought not be tried.
 843          */
 844         return (resplen);
 845 }
 846
 847 static int
 848 send_dg(res_state statp,
 849 #ifdef USE_KQUEUE
 850         int kq,
 851 #endif
 852         const u_char *buf, int buflen, u_char *ans,
 853         int anssiz, int *terrno, int ns, int tries, int *v_circuit,
 854         int *gotsomewhere)
 855 {
 856         const HEADER *hp = (const HEADER *) buf;
 857         HEADER *anhp = (HEADER *) ans;
 858         const struct sockaddr *nsap;
 859         int nsaplen;
 860         struct timespec now, timeout, finish;
 861         struct sockaddr_storage from;
 862         ISC_SOCKLEN_T fromlen;
 863         int resplen, seconds, n, s;
 864 #ifdef USE_KQUEUE
 865         struct kevent kv;
 866 #else
 867 #ifdef USE_POLL
 868         int     polltimeout;
 869         struct pollfd   pollfd;
 870 #else
 871         fd_set dsmask;
 872 #endif
 873 #endif
 874
 875         nsap = get_nsaddr(statp, ns);
 876         nsaplen = get_salen(nsap);
 877         if (EXT(statp).nssocks[ns] == -1) {
 878 #ifndef _LIBC
 879                 EXT(statp).nssocks[ns] = socket(nsap->sa_family, SOCK_DGRAM, 0);
 880 #else
 881                 EXT(statp).nssocks[ns] = _socket(nsap->sa_family, SOCK_DGRAM, 0);
 882 #endif
 883 #if !defined(USE_POLL) && !defined(USE_KQUEUE)
 884                 if (EXT(statp).nssocks[ns] > highestFD) {
 885                         res_nclose(statp);
 886                         errno = ENOTSOCK;
 887                 }
 888 #endif
 889                 if (EXT(statp).nssocks[ns] < 0) {
 890                         switch (errno) {
 891                         case EPROTONOSUPPORT:
 892 #ifdef EPFNOSUPPORT
 893                         case EPFNOSUPPORT:
 894 #endif
 895                         case EAFNOSUPPORT:
 896                                 Perror(statp, stderr, "socket(dg)", errno);
 897                                 return (0);
 898                         default:
 899                                 *terrno = errno;
 900                                 Perror(statp, stderr, "socket(dg)", errno);
 901                                 return (-1);
 902                         }
 903                 }
 904 #ifndef CANNOT_CONNECT_DGRAM
 905                 /*
 906                  * On a 4.3BSD+ machine (client and server,
 907                  * actually), sending to a nameserver datagram
 908                  * port with no nameserver will cause an
 909                  * ICMP port unreachable message to be returned.
 910                  * If our datagram socket is "connected" to the
 911                  * server, we get an ECONNREFUSED error on the next
 912                  * socket operation, and select returns if the
 913                  * error message is received.  We can thus detect
 914                  * the absence of a nameserver without timing out.
 915                  *
 916                  *
 917                  * When the option "insecure1" is specified, we'd
 918                  * rather expect to see responses from an "unknown"
 919                  * address.  In order to let the kernel accept such
 920                  * responses, do not connect the socket here.
 921                  * XXX: or do we need an explicit option to disable
 922                  * connecting?
 923                  */
 924                 if (!(statp->options & RES_INSECURE1) &&
 925 #ifndef _LIBC
 926                         connect(EXT(statp).nssocks[ns], nsap, nsaplen) < 0) {
 927 #else
 928                         _connect(EXT(statp).nssocks[ns], nsap, nsaplen) < 0) {
 929 #endif
 930                         Aerror(statp, stderr, "connect(dg)", errno, nsap,
 931                             nsaplen);
 932                         res_nclose(statp);
 933                         return (0);
 934                 }
 935 #endif /* !CANNOT_CONNECT_DGRAM */
 936                 Dprint(statp->options & RES_DEBUG,
 937                        (stdout, ";; new DG socket\n"))
 938         }
 939         s = EXT(statp).nssocks[ns];
 940 #ifndef CANNOT_CONNECT_DGRAM
 941                 if (statp->options & RES_INSECURE1) {
 942 #ifndef _LIBC
 943                 if (sendto(s,
 944 #else
 945                 if (_sendto(s,
 946 #endif
 947                 (const char*)buf, buflen, 0, nsap, nsaplen) != buflen) {
 948                         Aerror(statp, stderr, "sendto", errno, nsap, nsaplen);
 949                         res_nclose(statp);
 950                         return (0);
 951                 }
 952         } else if (send(s, (const char*)buf, buflen, 0) != buflen) {
 953                 Perror(statp, stderr, "send", errno);
 954                 res_nclose(statp);
 955                 return (0);
 956         }
 957 #else /* !CANNOT_CONNECT_DGRAM */
 958 #ifndef _LIBC
 959         if (sendto(s, (const char*)buf, buflen, 0, nsap, nsaplen) != buflen)
 960 #else
 961         if (_sendto(s, (const char*)buf, buflen, 0, nsap, nsaplen) != buflen)
 962 #endif
 963         {
 964                 Aerror(statp, stderr, "sendto", errno, nsap, nsaplen);
 965                 res_nclose(statp);
 966                 return (0);
 967         }
 968 #endif /* !CANNOT_CONNECT_DGRAM */
 969
 970         /*
 971          * Wait for reply.
 972          */
 973         seconds = (statp->retrans << tries);
 974         if (ns > 0)
 975                 seconds /= statp->nscount;
 976         if (seconds <= 0)
 977                 seconds = 1;
 978         now = evNowTime();
 979         timeout = evConsTime(seconds, 0);
 980         finish = evAddTime(now, timeout);
 981         goto nonow;
 982  wait:
 983         now = evNowTime();
 984  nonow:
 985 #ifndef USE_POLL
 986         if (evCmpTime(finish, now) > 0)
 987                 timeout = evSubTime(finish, now);
 988         else
 989                 timeout = evConsTime(0, 0);
 990 #ifdef USE_KQUEUE
 991         EV_SET(&kv, s, EVFILT_READ, EV_ADD | EV_ONESHOT, 0, 0, 0);
 992         n = _kevent(kq, &kv, 1, &kv, 1, &timeout);
 993 #else
 994         FD_ZERO(&dsmask);
 995         FD_SET(s, &dsmask);
 996         n = pselect(s + 1, &dsmask, NULL, NULL, &timeout, NULL);
 997 #endif
 998 #else
 999         timeout = evSubTime(finish, now);
1000         if (timeout.tv_sec < 0)
1001                 timeout = evConsTime(0, 0);
1002         polltimeout = 1000*timeout.tv_sec +
1003                 timeout.tv_nsec/1000000;
1004         pollfd.fd = s;
1005         pollfd.events = POLLRDNORM;
1006         n = poll(&pollfd, 1, polltimeout);
1007 #endif /* USE_POLL */
1008
1009         if (n == 0) {
1010                 Dprint(statp->options & RES_DEBUG, (stdout, ";; timeout\n"));
1011                 *gotsomewhere = 1;
1012                 return (0);
1013         }
1014         if (n < 0) {
1015                 if (errno == EINTR)
1016                         goto wait;
1017 #ifdef USE_KQUEUE
1018                 Perror(statp, stderr, "kevent", errno);
1019 #else
1020 #ifndef USE_POLL
1021                 Perror(statp, stderr, "select", errno);
1022 #else
1023                 Perror(statp, stderr, "poll", errno);
1024 #endif /* USE_POLL */
1025 #endif
1026                 res_nclose(statp);
1027                 return (0);
1028         }
1029 #ifdef USE_KQUEUE
1030         if (kv.ident != s)
1031                 goto wait;
1032 #endif
1033         errno = 0;
1034         fromlen = sizeof(from);
1035 #ifndef _LIBC
1036         resplen = recvfrom(s, (char*)ans, anssiz,0,
1037 #else
1038         resplen = _recvfrom(s, (char*)ans, anssiz,0,
1039 #endif
1040                            (struct sockaddr *)&from, &fromlen);
1041         if (resplen <= 0) {
1042                 Perror(statp, stderr, "recvfrom", errno);
1043                 res_nclose(statp);
1044                 return (0);
1045         }
1046         *gotsomewhere = 1;
1047         if (resplen < HFIXEDSZ) {
1048                 /*
1049                  * Undersized message.
1050                  */
1051                 Dprint(statp->options & RES_DEBUG,
1052                        (stdout, ";; undersized: %d\n",
1053                         resplen));
1054                 *terrno = EMSGSIZE;
1055                 res_nclose(statp);
1056                 return (0);
1057         }
1058         if (hp->id != anhp->id) {
1059                 /*
1060                  * response from old query, ignore it.
1061                  * XXX - potential security hazard could
1062                  *       be detected here.
1063                  */
1064                 DprintQ((statp->options & RES_DEBUG) ||
1065                         (statp->pfcode & RES_PRF_REPLY),
1066                         (stdout, ";; old answer:\n"),
1067                         ans, (resplen > anssiz) ? anssiz : resplen);
1068                 goto wait;
1069         }
1070         if (!(statp->options & RES_INSECURE1) &&
1071             !res_ourserver_p(statp, (struct sockaddr *)&from)) {
1072                 /*
1073                  * response from wrong server? ignore it.
1074                  * XXX - potential security hazard could
1075                  *       be detected here.
1076                  */
1077                 DprintQ((statp->options & RES_DEBUG) ||
1078                         (statp->pfcode & RES_PRF_REPLY),
1079                         (stdout, ";; not our server:\n"),
1080                         ans, (resplen > anssiz) ? anssiz : resplen);
1081                 goto wait;
1082         }
1083 #ifdef RES_USE_EDNS0
1084         if (anhp->rcode == FORMERR && (statp->options & RES_USE_EDNS0) != 0U) {
1085                 /*
1086                  * Do not retry if the server do not understand EDNS0.
1087                  * The case has to be captured here, as FORMERR packet do not
1088                  * carry query section, hence res_queriesmatch() returns 0.
1089                  */
1090                 DprintQ(statp->options & RES_DEBUG,
1091                         (stdout, "server rejected query with EDNS0:\n"),
1092                         ans, (resplen > anssiz) ? anssiz : resplen);
1093                 /* record the error */
1094                 statp->_flags |= RES_F_EDNS0ERR;
1095                 res_nclose(statp);
1096                 return (0);
1097         }
1098 #endif
1099         if (!(statp->options & RES_INSECURE2) &&
1100             !res_queriesmatch(buf, buf + buflen,
1101                               ans, ans + anssiz)) {
1102                 /*
1103                  * response contains wrong query? ignore it.
1104                  * XXX - potential security hazard could
1105                  *       be detected here.
1106                  */
1107                 DprintQ((statp->options & RES_DEBUG) ||
1108                         (statp->pfcode & RES_PRF_REPLY),
1109                         (stdout, ";; wrong query name:\n"),
1110                         ans, (resplen > anssiz) ? anssiz : resplen);
1111                 goto wait;
1112         }
1113         if (anhp->rcode == SERVFAIL ||
1114             anhp->rcode == NOTIMP ||
1115             anhp->rcode == REFUSED) {
1116                 DprintQ(statp->options & RES_DEBUG,
1117                         (stdout, "server rejected query:\n"),
1118                         ans, (resplen > anssiz) ? anssiz : resplen);
1119                 res_nclose(statp);
1120                 /* don't retry if called from dig */
1121                 if (!statp->pfcode)
1122                         return (0);
1123         }
1124         if (!(statp->options & RES_IGNTC) && anhp->tc) {
1125                 /*
1126                  * To get the rest of answer,
1127                  * use TCP with same server.
1128                  */
1129                 Dprint(statp->options & RES_DEBUG,
1130                        (stdout, ";; truncated answer\n"));
1131                 *v_circuit = 1;
1132                 res_nclose(statp);
1133                 return (1);
1134         }
1135         /*
1136          * All is well, or the error is fatal.  Signal that the
1137          * next nameserver ought not be tried.
1138          */
1139         return (resplen);
1140 }
1141
1142 static void
1143 Aerror(const res_state statp, FILE *file, const char *string, int error,
1144        const struct sockaddr *address, int alen)
1145 {
1146         int save = errno;
1147         char hbuf[NI_MAXHOST];
1148         char sbuf[NI_MAXSERV];
1149
1150         alen = alen;
1151
1152         if ((statp->options & RES_DEBUG) != 0U) {
1153                 if (getnameinfo(address, alen, hbuf, sizeof(hbuf),
1154                     sbuf, sizeof(sbuf), niflags)) {
1155                         strncpy(hbuf, "?", sizeof(hbuf) - 1);
1156                         hbuf[sizeof(hbuf) - 1] = '\0';
1157                         strncpy(sbuf, "?", sizeof(sbuf) - 1);
1158                         sbuf[sizeof(sbuf) - 1] = '\0';
1159                 }
1160                 fprintf(file, "res_send: %s ([%s].%s): %s\n",
1161                         string, hbuf, sbuf, strerror(error));
1162         }
1163         errno = save;
1164 }
1165
1166 static void
1167 Perror(const res_state statp, FILE *file, const char *string, int error) {
1168         int save = errno;
1169
1170         if ((statp->options & RES_DEBUG) != 0U)
1171                 fprintf(file, "res_send: %s: %s\n",
1172                         string, strerror(error));
1173         errno = save;
1174 }
1175
1176 static int
1177 sock_eq(struct sockaddr *a, struct sockaddr *b) {
1178         struct sockaddr_in *a4, *b4;
1179         struct sockaddr_in6 *a6, *b6;
1180
1181         if (a->sa_family != b->sa_family)
1182                 return 0;
1183         switch (a->sa_family) {
1184         case AF_INET:
1185                 a4 = (struct sockaddr_in *)a;
1186                 b4 = (struct sockaddr_in *)b;
1187                 return a4->sin_port == b4->sin_port &&
1188                     a4->sin_addr.s_addr == b4->sin_addr.s_addr;
1189         case AF_INET6:
1190                 a6 = (struct sockaddr_in6 *)a;
1191                 b6 = (struct sockaddr_in6 *)b;
1192                 return a6->sin6_port == b6->sin6_port &&
1193 #ifdef HAVE_SIN6_SCOPE_ID
1194                     a6->sin6_scope_id == b6->sin6_scope_id &&
1195 #endif
1196                     IN6_ARE_ADDR_EQUAL(&a6->sin6_addr, &b6->sin6_addr);
1197         default:
1198                 return 0;
1199         }
1200 }
1201
1202 #if defined(NEED_PSELECT) && !defined(USE_POLL) && !defined(USE_KQUEUE)
1203 /* XXX needs to move to the porting library. */
1204 static int
1205 pselect(int nfds, void *rfds, void *wfds, void *efds,
1206         struct timespec *tsp, const sigset_t *sigmask)
1207 {
1208         struct timeval tv, *tvp;
1209         sigset_t sigs;
1210         int n;
1211
1212         if (tsp) {
1213                 tvp = &tv;
1214                 tv = evTimeVal(*tsp);
1215         } else
1216                 tvp = NULL;
1217         if (sigmask)
1218                 sigprocmask(SIG_SETMASK, sigmask, &sigs);
1219         n = select(nfds, rfds, wfds, efds, tvp);
1220         if (sigmask)
1221                 sigprocmask(SIG_SETMASK, &sigs, NULL);
1222         if (tsp)
1223                 *tsp = evTimeSpec(tv);
1224         return (n);
1225 }
1226 #endif