resolv/res_send.c

   1 /*
   2  * Copyright (c) 1985, 1989, 1993
   3  *    The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 /*
  31  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  32  *
  33  * Permission to use, copy, modify, and distribute this software for any
  34  * purpose with or without fee is hereby granted, provided that the above
  35  * copyright notice and this permission notice appear in all copies, and that
  36  * the name of Digital Equipment Corporation not be used in advertising or
  37  * publicity pertaining to distribution of the document or software without
  38  * specific, written prior permission.
  39  *
  40  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  41  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  42  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  43  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  44  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  45  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  46  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  47  * SOFTWARE.
  48  */
  49
  50 /*
  51  * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
  52  *
  53  * Permission to use, copy, modify, and distribute this software for any
  54  * purpose with or without fee is hereby granted, provided that the above
  55  * copyright notice and this permission notice appear in all copies.
  56  *
  57  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
  58  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  59  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  60  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  61  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  62  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  63  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  64  * SOFTWARE.
  65  */
  66
  67 #if defined(LIBC_SCCS) && !defined(lint)
  68 static const char sccsid[] = "@(#)res_send.c    8.1 (Berkeley) 6/4/93";
  69 static const char rcsid[] = "$BINDId: res_send.c,v 8.38 2000/03/30 20:16:51 vixie Exp $";
  70 #endif /* LIBC_SCCS and not lint */
  71
  72 /*
  73  * Send query to name server and wait for reply.
  74  */
  75
  76 #include <sys/types.h>
  77 #include <sys/param.h>
  78 #include <sys/time.h>
  79 #include <sys/socket.h>
  80 #include <sys/uio.h>
  81 #ifdef _LIBC
  82 #include <sys/poll.h>
  83 #endif
  84
  85 #include <netinet/in.h>
  86 #include <arpa/nameser.h>
  87 #include <arpa/inet.h>
  88
  89 #include <errno.h>
  90 #include <netdb.h>
  91 #include <resolv.h>
  92 #include <signal.h>
  93 #include <stdio.h>
  94 #include <stdlib.h>
  95 #include <string.h>
  96 #include <unistd.h>
  97
  98 #ifndef _LIBC
  99 #include <isc/eventlib.h>
 100 #else
 101
 102 /* From ev_streams.c.  */
 103
 104 static inline struct iovec
 105 evConsIovec(void *buf, size_t cnt) {
 106         struct iovec ret;
 107
 108         memset(&ret, 0xf5, sizeof ret);
 109         ret.iov_base = buf;
 110         ret.iov_len = cnt;
 111         return (ret);
 112 }
 113
 114 /* From ev_timers.c.  */
 115
 116 #define BILLION 1000000000
 117
 118 static inline struct timespec
 119 evTimeSpec(struct timeval tv) {
 120         struct timespec ts;
 121
 122         ts.tv_sec = tv.tv_sec;
 123         ts.tv_nsec = tv.tv_usec * 1000;
 124         return (ts);
 125 }
 126
 127 static inline struct timespec
 128 evConsTime(time_t sec, long nsec) {
 129         struct timespec x;
 130
 131         x.tv_sec = sec;
 132         x.tv_nsec = nsec;
 133         return (x);
 134 }
 135
 136 static inline struct timespec
 137 evAddTime(struct timespec addend1, struct timespec addend2) {
 138         struct timespec x;
 139
 140         x.tv_sec = addend1.tv_sec + addend2.tv_sec;
 141         x.tv_nsec = addend1.tv_nsec + addend2.tv_nsec;
 142         if (x.tv_nsec >= BILLION) {
 143                 x.tv_sec++;
 144                 x.tv_nsec -= BILLION;
 145         }
 146         return (x);
 147 }
 148
 149 static inline struct timespec
 150 evSubTime(struct timespec minuend, struct timespec subtrahend) {
 151         struct timespec x;
 152
 153         x.tv_sec = minuend.tv_sec - subtrahend.tv_sec;
 154         if (minuend.tv_nsec >= subtrahend.tv_nsec)
 155                 x.tv_nsec = minuend.tv_nsec - subtrahend.tv_nsec;
 156         else {
 157                 x.tv_nsec = BILLION - subtrahend.tv_nsec + minuend.tv_nsec;
 158                 x.tv_sec--;
 159         }
 160         return (x);
 161 }
 162
 163 static inline int
 164 evCmpTime(struct timespec a, struct timespec b) {
 165         long x = a.tv_sec - b.tv_sec;
 166
 167         if (x == 0L)
 168                 x = a.tv_nsec - b.tv_nsec;
 169         return (x < 0L ? (-1) : x > 0L ? (1) : (0));
 170 }
 171
 172 static inline struct timespec
 173 evNowTime() {
 174         struct timeval now;
 175
 176         if (gettimeofday(&now, NULL) < 0)
 177                 return (evConsTime(0, 0));
 178         return (evTimeSpec(now));
 179 }
 180
 181 #endif
 182
 183 /* Options.  Leave them on. */
 184 /* #undef DEBUG */
 185 #include "res_debug.h"
 186
 187 #define EXT(res) ((res)->_u._ext)
 188
 189 #ifndef _LIBC
 190 static const int highestFD = FD_SETSIZE - 1;
 191 #endif
 192
 193 /* Forward. */
 194
 195 static int              send_vc(res_state, const u_char *, int,
 196                                 u_char *, int, int *, int);
 197 static int              send_dg(res_state, const u_char *, int,
 198                                 u_char *, int, int *, int,
 199                                 int *, int *);
 200 #ifdef DEBUG
 201 static void             Aerror(const res_state, FILE *, const char *, int,
 202                                struct sockaddr_in);
 203 static void             Perror(const res_state, FILE *, const char *, int);
 204 #endif
 205 #ifdef _LIBC
 206 static int              sock_eq(struct sockaddr_in6 *, struct sockaddr_in6 *);
 207 #else
 208 static int              sock_eq(struct sockaddr_in *, struct sockaddr_in *);
 209 #endif
 210 #ifdef NEED_PSELECT
 211 static int              pselect(int, void *, void *, void *,
 212                                 struct timespec *,
 213                                 const sigset_t *);
 214 #endif
 215
 216 /* Reachover. */
 217
 218 #ifdef _LIBC
 219 static void convaddr4to6(struct sockaddr_in6 *sa);
 220 #endif
 221 void res_pquery(const res_state, const u_char *, int, FILE *);
 222
 223 /* Public. */
 224
 225 /* int
 226  * res_isourserver(ina)
 227  *      looks up "ina" in _res.ns_addr_list[]
 228  * returns:
 229  *      0  : not found
 230  *      >0 : found
 231  * author:
 232  *      paul vixie, 29may94
 233  */
 234 int
 235 #ifdef _LIBC
 236 res_ourserver_p(const res_state statp, const struct sockaddr_in6 *inp)
 237 #else
 238 res_ourserver_p(const res_state statp, const struct sockaddr_in *inp)
 239 #endif
 240 {
 241         struct sockaddr_in ina;
 242         int ns;
 243
 244 #ifdef _LIBC
 245         if (inp->sin6_family == AF_INET) {
 246             ina = *(struct sockaddr_in *)inp;
 247
 248             for (ns = 0;  ns < MAXNS;  ns++) {
 249                 const struct sockaddr_in *srv =
 250                     (struct sockaddr_in *)EXT(statp).nsaddrs[ns];
 251
 252                 if ((srv != NULL) && (srv->sin_family == AF_INET) &&
 253                     (srv->sin_port == ina.sin_port) &&
 254                     (srv->sin_addr.s_addr == INADDR_ANY ||
 255                      srv->sin_addr.s_addr == ina.sin_addr.s_addr))
 256                     return (1);
 257             }
 258         } else if (inp->sin6_family == AF_INET6) {
 259             for (ns = 0;  ns < MAXNS;  ns++) {
 260                 const struct sockaddr_in6 *srv = EXT(statp).nsaddrs[ns];
 261                 if ((srv != NULL) && (srv->sin6_family == AF_INET6) &&
 262                     (srv->sin6_port == inp->sin6_port) &&
 263                     !(memcmp(&srv->sin6_addr, &in6addr_any,
 264                              sizeof (struct in6_addr)) &&
 265                       memcmp(&srv->sin6_addr, &inp->sin6_addr,
 266                              sizeof (struct in6_addr))))
 267                     return (1);
 268             }
 269         }
 270 #else
 271         ina = *inp;
 272         for (ns = 0; ns < statp->nscount; ns++) {
 273                 const struct sockaddr_in *srv = &statp->nsaddr_list[ns];
 274
 275                 if (srv->sin_family == ina.sin_family &&
 276                     srv->sin_port == ina.sin_port &&
 277                     (srv->sin_addr.s_addr == INADDR_ANY ||
 278                      srv->sin_addr.s_addr == ina.sin_addr.s_addr))
 279                         return (1);
 280         }
 281 #endif
 282         return (0);
 283 }
 284
 285 /* int
 286  * res_nameinquery(name, type, class, buf, eom)
 287  *      look for (name,type,class) in the query section of packet (buf,eom)
 288  * requires:
 289  *      buf + HFIXEDSZ <= eom
 290  * returns:
 291  *      -1 : format error
 292  *      0  : not found
 293  *      >0 : found
 294  * author:
 295  *      paul vixie, 29may94
 296  */
 297 int
 298 res_nameinquery(const char *name, int type, int class,
 299                 const u_char *buf, const u_char *eom)
 300 {
 301         const u_char *cp = buf + HFIXEDSZ;
 302         int qdcount = ntohs(((HEADER*)buf)->qdcount);
 303
 304         while (qdcount-- > 0) {
 305                 char tname[MAXDNAME+1];
 306                 int n, ttype, tclass;
 307
 308                 n = dn_expand(buf, eom, cp, tname, sizeof tname);
 309                 if (n < 0)
 310                         return (-1);
 311                 cp += n;
 312                 if (cp + 2 * INT16SZ > eom)
 313                         return (-1);
 314                 ttype = ns_get16(cp); cp += INT16SZ;
 315                 tclass = ns_get16(cp); cp += INT16SZ;
 316                 if (ttype == type && tclass == class &&
 317                     ns_samename(tname, name) == 1)
 318                         return (1);
 319         }
 320         return (0);
 321 }
 322
 323 /* int
 324  * res_queriesmatch(buf1, eom1, buf2, eom2)
 325  *      is there a 1:1 mapping of (name,type,class)
 326  *      in (buf1,eom1) and (buf2,eom2)?
 327  * returns:
 328  *      -1 : format error
 329  *      0  : not a 1:1 mapping
 330  *      >0 : is a 1:1 mapping
 331  * author:
 332  *      paul vixie, 29may94
 333  */
 334 int
 335 res_queriesmatch(const u_char *buf1, const u_char *eom1,
 336                  const u_char *buf2, const u_char *eom2)
 337 {
 338         const u_char *cp = buf1 + HFIXEDSZ;
 339         int qdcount = ntohs(((HEADER*)buf1)->qdcount);
 340
 341         if (buf1 + HFIXEDSZ > eom1 || buf2 + HFIXEDSZ > eom2)
 342                 return (-1);
 343
 344         /*
 345          * Only header section present in replies to
 346          * dynamic update packets.
 347          */
 348         if ((((HEADER *)buf1)->opcode == ns_o_update) &&
 349             (((HEADER *)buf2)->opcode == ns_o_update))
 350                 return (1);
 351
 352         if (qdcount != ntohs(((HEADER*)buf2)->qdcount))
 353                 return (0);
 354         while (qdcount-- > 0) {
 355                 char tname[MAXDNAME+1];
 356                 int n, ttype, tclass;
 357
 358                 n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
 359                 if (n < 0)
 360                         return (-1);
 361                 cp += n;
 362                 if (cp + 2 * INT16SZ > eom1)
 363                         return (-1);
 364                 ttype = ns_get16(cp);   cp += INT16SZ;
 365                 tclass = ns_get16(cp); cp += INT16SZ;
 366                 if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))
 367                         return (0);
 368         }
 369         return (1);
 370 }
 371
 372 int
 373 res_nsend(res_state statp,
 374           const u_char *buf, int buflen, u_char *ans, int anssiz)
 375 {
 376         int gotsomewhere, terrno, try, v_circuit, resplen, ns, n;
 377
 378         if (statp->nscount == 0) {
 379                 __set_errno (ESRCH);
 380                 return (-1);
 381         }
 382         if (anssiz < HFIXEDSZ) {
 383                 __set_errno (EINVAL);
 384                 return (-1);
 385         }
 386         DprintQ((statp->options & RES_DEBUG) || (statp->pfcode & RES_PRF_QUERY),
 387                 (stdout, ";; res_send()\n"), buf, buflen);
 388         v_circuit = (statp->options & RES_USEVC) || buflen > PACKETSZ;
 389         gotsomewhere = 0;
 390         terrno = ETIMEDOUT;
 391
 392         /*
 393          * If the ns_addr_list in the resolver context has changed, then
 394          * invalidate our cached copy and the associated timing data.
 395          */
 396         if (EXT(statp).nscount != 0) {
 397                 int needclose = 0;
 398
 399                 if (EXT(statp).nscount != statp->nscount)
 400                         needclose++;
 401                 else
 402                         for (ns = 0; ns < statp->nscount; ns++)
 403 #ifdef _LIBC
 404                                 if (!sock_eq((struct sockaddr_in6 *)
 405                                              &statp->nsaddr_list[ns],
 406                                              EXT(statp).nsaddrs[ns]))
 407 #else
 408                                 if (!sock_eq(&statp->nsaddr_list[ns],
 409                                              &EXT(statp).nsaddrs[ns]))
 410 #endif
 411                                 {
 412                                         needclose++;
 413                                         break;
 414                                 }
 415                 if (needclose)
 416                         res_nclose(statp);
 417         }
 418
 419         /*
 420          * Maybe initialize our private copy of the ns_addr_list.
 421          */
 422         if (EXT(statp).nscount == 0) {
 423 #ifdef _LIBC
 424                 n = 0;
 425 #endif
 426                 for (ns = 0; ns < statp->nscount; ns++) {
 427 #ifdef _LIBC
 428                         /* find a hole */
 429                         while ((n < MAXNS) &&
 430                             (EXT(statp).nsaddrs[n] != NULL) &&
 431                             (EXT(statp).nsaddrs[n]->sin6_family == AF_INET6) &&
 432                             !IN6_IS_ADDR_V4MAPPED(
 433                                 &EXT(statp).nsaddrs[n]->sin6_addr))
 434                                 n++;
 435                         if (n == MAXNS)
 436                                 break;
 437
 438                         if (EXT(statp).nsaddrs[n] == NULL)
 439                                 EXT(statp).nsaddrs[n] =
 440                                     malloc(sizeof (struct sockaddr_in6));
 441                         if (EXT(statp).nsaddrs[n] != NULL) {
 442                                 memcpy(EXT(statp).nsaddrs[n],
 443                                        &statp->nsaddr_list[ns],
 444                                        sizeof (struct sockaddr_in));
 445                                 EXT(statp).nstimes[n] = RES_MAXTIME;
 446                                 EXT(statp).nssocks[n] = -1;
 447                                 n++;
 448                         }
 449 #else
 450                         EXT(statp).nsaddrs[ns] = statp->nsaddr_list[ns];
 451                         EXT(statp).nstimes[ns] = RES_MAXTIME;
 452                         EXT(statp).nssocks[ns] = -1;
 453 #endif
 454                 }
 455                 EXT(statp).nscount = statp->nscount;
 456 #ifdef _LIBC
 457                 /* If holes left, free memory and set to NULL */
 458                 while (n < MAXNS) {
 459                         if ((EXT(statp).nsaddrs[n] != NULL) &&
 460                             ((EXT(statp).nsaddrs[n]->sin6_family != AF_INET6)
 461                             || IN6_IS_ADDR_V4MAPPED(
 462                                    &EXT(statp).nsaddrs[n]->sin6_addr))) {
 463                                 free(EXT(statp).nsaddrs[n]);
 464                                 EXT(statp).nsaddrs[n] = NULL;
 465                         }
 466                         n++;
 467                 }
 468 #endif
 469         }
 470
 471         /*
 472          * Some resolvers want to even out the load on their nameservers.
 473          * Note that RES_BLAST overrides RES_ROTATE.
 474          */
 475         if ((statp->options & RES_ROTATE) != 0 &&
 476             (statp->options & RES_BLAST) == 0) {
 477 #ifdef _LIBC
 478                 struct sockaddr_in6 *ina;
 479                 int lastns = statp->nscount + EXT(statp).nscount6 - 1;
 480
 481                 ina = EXT(statp).nsaddrs[0];
 482                 for (ns = 0; ns < lastns; ns++)
 483                         EXT(statp).nsaddrs[ns] = EXT(statp).nsaddrs[ns + 1];
 484                 EXT(statp).nsaddrs[lastns] = ina;
 485 #else
 486                 struct sockaddr_in ina;
 487                 int lastns = statp->nscount - 1;
 488
 489                 ina = statp->nsaddr_list[0];
 490                 for (ns = 0; ns < lastns; ns++)
 491                         statp->nsaddr_list[ns] = statp->nsaddr_list[ns + 1];
 492                 statp->nsaddr_list[lastns] = ina;
 493 #endif
 494         }
 495
 496         /*
 497          * Send request, RETRY times, or until successful.
 498          */
 499         for (try = 0; try < statp->retry; try++) {
 500 #ifdef _LIBC
 501             for (ns = 0; ns < MAXNS; ns++)
 502 #else
 503             for (ns = 0; ns < statp->nscount; ns++)
 504 #endif
 505             {
 506 #ifdef _LIBC
 507                 struct sockaddr_in6 *nsap = EXT(statp).nsaddrs[ns];
 508
 509                 if (nsap == NULL)
 510                         goto next_ns;
 511 #else
 512                 struct sockaddr_in *nsap = &statp->nsaddr_list[ns];
 513 #endif
 514  same_ns:
 515                 if (statp->qhook) {
 516                         int done = 0, loops = 0;
 517
 518                         do {
 519                                 res_sendhookact act;
 520
 521 #ifdef _LIBC
 522                                 act = (*statp->qhook)((struct sockaddr_in **)
 523                                                       &nsap, &buf, &buflen,
 524                                                       ans, anssiz, &resplen);
 525 #else
 526                                 act = (*statp->qhook)(&nsap, &buf, &buflen,
 527                                                       ans, anssiz, &resplen);
 528 #endif
 529                                 switch (act) {
 530                                 case res_goahead:
 531                                         done = 1;
 532                                         break;
 533                                 case res_nextns:
 534                                         res_nclose(statp);
 535                                         goto next_ns;
 536                                 case res_done:
 537                                         return (resplen);
 538                                 case res_modified:
 539                                         /* give the hook another try */
 540                                         if (++loops < 42) /*doug adams*/
 541                                                 break;
 542                                         /*FALLTHROUGH*/
 543                                 case res_error:
 544                                         /*FALLTHROUGH*/
 545                                 default:
 546                                         return (-1);
 547                                 }
 548                         } while (!done);
 549                 }
 550
 551                 Dprint(statp->options & RES_DEBUG,
 552                        (stdout, ";; Querying server (# %d) address = %s\n",
 553                         ns + 1, inet_ntoa(nsap->sin_addr)));
 554
 555                 if (v_circuit) {
 556                         /* Use VC; at most one attempt per server. */
 557                         try = statp->retry;
 558                         n = send_vc(statp, buf, buflen, ans, anssiz, &terrno,
 559                                     ns);
 560                         if (n < 0)
 561                                 return (-1);
 562                         if (n == 0)
 563                                 goto next_ns;
 564                         resplen = n;
 565                 } else {
 566                         /* Use datagrams. */
 567                         n = send_dg(statp, buf, buflen, ans, anssiz, &terrno,
 568                                     ns, &v_circuit, &gotsomewhere);
 569                         if (n < 0)
 570                                 return (-1);
 571                         if (n == 0)
 572                                 goto next_ns;
 573                         if (v_circuit)
 574                                 goto same_ns;
 575                         resplen = n;
 576                 }
 577
 578                 Dprint((statp->options & RES_DEBUG) ||
 579                        ((statp->pfcode & RES_PRF_REPLY) &&
 580                         (statp->pfcode & RES_PRF_HEAD1)),
 581                        (stdout, ";; got answer:\n"));
 582
 583                 DprintQ((statp->options & RES_DEBUG) ||
 584                         (statp->pfcode & RES_PRF_REPLY),
 585                         (stdout, ""),
 586                         ans, (resplen > anssiz) ? anssiz : resplen);
 587
 588                 /*
 589                  * If we have temporarily opened a virtual circuit,
 590                  * or if we haven't been asked to keep a socket open,
 591                  * close the socket.
 592                  */
 593                 if ((v_circuit && (statp->options & RES_USEVC) == 0) ||
 594                     (statp->options & RES_STAYOPEN) == 0) {
 595                         res_nclose(statp);
 596                 }
 597                 if (statp->rhook) {
 598                         int done = 0, loops = 0;
 599
 600                         do {
 601                                 res_sendhookact act;
 602
 603 #ifdef _LIBC
 604                                 act = (*statp->rhook)((struct sockaddr_in *)
 605                                                       nsap, buf, buflen,
 606                                                       ans, anssiz, &resplen);
 607 #else
 608                                 act = (*statp->rhook)(nsap, buf, buflen,
 609                                                       ans, anssiz, &resplen);
 610 #endif
 611                                 switch (act) {
 612                                 case res_goahead:
 613                                 case res_done:
 614                                         done = 1;
 615                                         break;
 616                                 case res_nextns:
 617                                         res_nclose(statp);
 618                                         goto next_ns;
 619                                 case res_modified:
 620                                         /* give the hook another try */
 621                                         if (++loops < 42) /*doug adams*/
 622                                                 break;
 623                                         /*FALLTHROUGH*/
 624                                 case res_error:
 625                                         /*FALLTHROUGH*/
 626                                 default:
 627                                         return (-1);
 628                                 }
 629                         } while (!done);
 630
 631                 }
 632                 return (resplen);
 633  next_ns: ;
 634            } /*foreach ns*/
 635         } /*foreach retry*/
 636         res_nclose(statp);
 637         if (!v_circuit) {
 638                 if (!gotsomewhere)
 639                         __set_errno (ECONNREFUSED);     /* no nameservers found */
 640                 else
 641                         __set_errno (ETIMEDOUT);        /* no answer obtained */
 642         } else
 643                 __set_errno (terrno);
 644         return (-1);
 645 }
 646
 647 /* Private */
 648
 649 static int
 650 send_vc(res_state statp,
 651         const u_char *buf, int buflen, u_char *ans, int anssiz,
 652         int *terrno, int ns)
 653 {
 654         const HEADER *hp = (HEADER *) buf;
 655         HEADER *anhp = (HEADER *) ans;
 656 #ifdef _LIBC
 657         struct sockaddr_in6 *nsap = EXT(statp).nsaddrs[ns];
 658 #else
 659         struct sockaddr_in *nsap = &statp->nsaddr_list[ns];
 660 #endif
 661         int truncating, connreset, resplen, n;
 662         struct iovec iov[2];
 663         u_short len;
 664         u_char *cp;
 665
 666         connreset = 0;
 667  same_ns:
 668         truncating = 0;
 669
 670         /* Are we still talking to whom we want to talk to? */
 671         if (statp->_vcsock >= 0 && (statp->_flags & RES_F_VC) != 0) {
 672 #ifdef _LIBC
 673                 struct sockaddr_in6 peer;
 674 #else
 675                 struct sockaddr_in peer;
 676 #endif
 677                 int size = sizeof peer;
 678
 679                 if (getpeername(statp->_vcsock,
 680                                 (struct sockaddr *)&peer, &size) < 0 ||
 681                     !sock_eq(&peer, nsap)) {
 682                         res_nclose(statp);
 683                         statp->_flags &= ~RES_F_VC;
 684                 }
 685         }
 686
 687         if (statp->_vcsock < 0 || (statp->_flags & RES_F_VC) == 0) {
 688                 if (statp->_vcsock >= 0)
 689                         res_nclose(statp);
 690
 691 #ifdef _LIBC
 692                 statp->_vcsock = socket(nsap->sin6_family, SOCK_STREAM, 0);
 693 #else
 694                 statp->_vcsock = socket(PF_INET, SOCK_STREAM, 0);
 695                 if (statp->_vcsock > highestFD) {
 696                         res_nclose(statp);
 697                         __set_errno (ENOTSOCK);
 698                 }
 699 #endif
 700                 if (statp->_vcsock < 0) {
 701                         *terrno = errno;
 702                         Perror(statp, stderr, "socket(vc)", errno);
 703                         return (-1);
 704                 }
 705                 __set_errno (0);
 706                 if (connect(statp->_vcsock, (struct sockaddr *)nsap,
 707                             sizeof *nsap) < 0) {
 708                         *terrno = errno;
 709                         Aerror(statp, stderr, "connect/vc", errno, *nsap);
 710                         res_nclose(statp);
 711                         return (0);
 712                 }
 713                 statp->_flags |= RES_F_VC;
 714         }
 715
 716         /*
 717          * Send length & message
 718          */
 719         putshort((u_short)buflen, (u_char*)&len);
 720         iov[0] = evConsIovec(&len, INT16SZ);
 721         iov[1] = evConsIovec((void*)buf, buflen);
 722         if (writev(statp->_vcsock, iov, 2) != (INT16SZ + buflen)) {
 723                 *terrno = errno;
 724                 Perror(statp, stderr, "write failed", errno);
 725                 res_nclose(statp);
 726                 return (0);
 727         }
 728         /*
 729          * Receive length & response
 730          */
 731  read_len:
 732         cp = ans;
 733         len = INT16SZ;
 734         while ((n = read(statp->_vcsock, (char *)cp, (int)len)) > 0) {
 735                 cp += n;
 736                 if ((len -= n) <= 0)
 737                         break;
 738         }
 739         if (n <= 0) {
 740                 *terrno = errno;
 741                 Perror(statp, stderr, "read failed", errno);
 742                 res_nclose(statp);
 743                 /*
 744                  * A long running process might get its TCP
 745                  * connection reset if the remote server was
 746                  * restarted.  Requery the server instead of
 747                  * trying a new one.  When there is only one
 748                  * server, this means that a query might work
 749                  * instead of failing.  We only allow one reset
 750                  * per query to prevent looping.
 751                  */
 752                 if (*terrno == ECONNRESET && !connreset) {
 753                         connreset = 1;
 754                         res_nclose(statp);
 755                         goto same_ns;
 756                 }
 757                 res_nclose(statp);
 758                 return (0);
 759         }
 760         resplen = ns_get16(ans);
 761         if (resplen > anssiz) {
 762                 Dprint(statp->options & RES_DEBUG,
 763                        (stdout, ";; response truncated\n")
 764                        );
 765                 truncating = 1;
 766                 len = anssiz;
 767         } else
 768                 len = resplen;
 769         if (len < HFIXEDSZ) {
 770                 /*
 771                  * Undersized message.
 772                  */
 773                 Dprint(statp->options & RES_DEBUG,
 774                        (stdout, ";; undersized: %d\n", len));
 775                 *terrno = EMSGSIZE;
 776                 res_nclose(statp);
 777                 return (0);
 778         }
 779         cp = ans;
 780         while (len != 0 && (n = read(statp->_vcsock, (char *)cp, (int)len)) > 0){
 781                 cp += n;
 782                 len -= n;
 783         }
 784         if (n <= 0) {
 785                 *terrno = errno;
 786                 Perror(statp, stderr, "read(vc)", errno);
 787                 res_nclose(statp);
 788                 return (0);
 789         }
 790         if (truncating) {
 791                 /*
 792                  * Flush rest of answer so connection stays in synch.
 793                  */
 794                 anhp->tc = 1;
 795                 len = resplen - anssiz;
 796                 while (len != 0) {
 797                         char junk[PACKETSZ];
 798
 799                         n = read(statp->_vcsock, junk,
 800                                  (len > sizeof junk) ? sizeof junk : len);
 801                         if (n > 0)
 802                                 len -= n;
 803                         else
 804                                 break;
 805                 }
 806         }
 807         /*
 808          * If the calling applicating has bailed out of
 809          * a previous call and failed to arrange to have
 810          * the circuit closed or the server has got
 811          * itself confused, then drop the packet and
 812          * wait for the correct one.
 813          */
 814         if (hp->id != anhp->id) {
 815                 DprintQ((statp->options & RES_DEBUG) ||
 816                         (statp->pfcode & RES_PRF_REPLY),
 817                         (stdout, ";; old answer (unexpected):\n"),
 818                         ans, (resplen > anssiz) ? anssiz: resplen);
 819                 goto read_len;
 820         }
 821
 822         /*
 823          * All is well, or the error is fatal.  Signal that the
 824          * next nameserver ought not be tried.
 825          */
 826         return (resplen);
 827 }
 828
 829 static int
 830 send_dg(res_state statp,
 831         const u_char *buf, int buflen, u_char *ans, int anssiz,
 832         int *terrno, int ns, int *v_circuit, int *gotsomewhere)
 833 {
 834         const HEADER *hp = (HEADER *) buf;
 835         HEADER *anhp = (HEADER *) ans;
 836 #ifdef _LIBC
 837         struct sockaddr_in6 *nsap = EXT(statp).nsaddrs[ns];
 838 #else
 839         const struct sockaddr_in *nsap = &statp->nsaddr_list[ns];
 840 #endif
 841         struct timespec now, timeout, finish;
 842 #ifdef _LIBC
 843         struct pollfd pfd[1];
 844         int ptimeout;
 845         struct sockaddr_in6 from;
 846         static int socket_pf = 0;
 847 #else
 848         fd_set dsmask;
 849         struct sockaddr_in from;
 850 #endif
 851         int fromlen, resplen, seconds, n, s;
 852
 853         if (EXT(statp).nssocks[ns] == -1) {
 854 #ifdef _LIBC
 855                 /* only try IPv6 if IPv6 NS and if not failed before */
 856                 if ((EXT(statp).nscount6 > 0) && (socket_pf != PF_INET)) {
 857                         EXT(statp).nssocks[ns] =
 858                             socket(PF_INET6, SOCK_DGRAM, 0);
 859                         socket_pf = EXT(statp).nssocks[ns] < 0 ? PF_INET
 860                                                                : PF_INET6;
 861                 }
 862                 if (EXT(statp).nssocks[ns] < 0)
 863                         EXT(statp).nssocks[ns] = socket(PF_INET, SOCK_DGRAM, 0);
 864 #else
 865                 EXT(statp).nssocks[ns] = socket(PF_INET, SOCK_DGRAM, 0);
 866                 if (EXT(statp).nssocks[ns] > highestFD) {
 867                         res_nclose(statp);
 868                         __set_errno (ENOTSOCK);
 869                 }
 870 #endif
 871                 if (EXT(statp).nssocks[ns] < 0) {
 872                         *terrno = errno;
 873                         Perror(statp, stderr, "socket(dg)", errno);
 874                         return (-1);
 875                 }
 876 #ifndef CANNOT_CONNECT_DGRAM
 877 #ifdef _LIBC
 878                 /* If IPv6 socket and nsap is IPv4, make it IPv4-mapped */
 879                 if ((socket_pf == PF_INET6) && (nsap->sin6_family == AF_INET))
 880                         convaddr4to6(nsap);
 881 #endif
 882                 /*
 883                  * On a 4.3BSD+ machine (client and server,
 884                  * actually), sending to a nameserver datagram
 885                  * port with no nameserver will cause an
 886                  * ICMP port unreachable message to be returned.
 887                  * If our datagram socket is "connected" to the
 888                  * server, we get an ECONNREFUSED error on the next
 889                  * socket operation, and select returns if the
 890                  * error message is received.  We can thus detect
 891                  * the absence of a nameserver without timing out.
 892                  */
 893                 if (connect(EXT(statp).nssocks[ns], (struct sockaddr *)nsap,
 894                             sizeof *nsap) < 0) {
 895                         Aerror(statp, stderr, "connect(dg)", errno, *nsap);
 896                         res_nclose(statp);
 897                         return (0);
 898                 }
 899 #endif /* !CANNOT_CONNECT_DGRAM */
 900                 Dprint(statp->options & RES_DEBUG,
 901                        (stdout, ";; new DG socket\n"))
 902         }
 903         s = EXT(statp).nssocks[ns];
 904 #ifndef CANNOT_CONNECT_DGRAM
 905         if (send(s, (char*)buf, buflen, 0) != buflen) {
 906                 Perror(statp, stderr, "send", errno);
 907                 res_nclose(statp);
 908                 return (0);
 909         }
 910 #else /* !CANNOT_CONNECT_DGRAM */
 911 #ifdef _LIBC
 912         /* If IPv6 socket and nsap is IPv4, make it IPv4-mapped */
 913         if ((socket_pf == PF_INET6) && (nsap->sin6_family == AF_INET))
 914                 convaddr4to6(nsap);
 915 #endif
 916         if (sendto(s, (char*)buf, buflen, 0,
 917                    (struct sockaddr *)nsap, sizeof *nsap) != buflen)
 918         {
 919                 Aerror(statp, stderr, "sendto", errno, *nsap);
 920                 res_nclose(statp);
 921                 return (0);
 922         }
 923 #endif /* !CANNOT_CONNECT_DGRAM */
 924
 925         /*
 926          * Wait for reply.
 927          */
 928         seconds = (statp->retrans << ns);
 929         if (ns > 0)
 930                 seconds /= statp->nscount;
 931         if (seconds <= 0)
 932                 seconds = 1;
 933         now = evNowTime();
 934         timeout = evConsTime(seconds, 0);
 935         finish = evAddTime(now, timeout);
 936  wait:
 937 #ifdef _LIBC
 938         /* Convert struct timespec in milliseconds.  */
 939         ptimeout = timeout.tv_sec * 1000 + timeout.tv_nsec / 1000000;
 940
 941         pfd[0].fd = s;
 942         pfd[0].events = POLLIN;
 943         n = __poll (pfd, 1, ptimeout);
 944 #else
 945         FD_ZERO(&dsmask);
 946         FD_SET(s, &dsmask);
 947         n = pselect(s + 1, &dsmask, NULL, NULL, &timeout, NULL);
 948 #endif
 949         if (n == 0) {
 950                 Dprint(statp->options & RES_DEBUG, (stdout, ";; timeout\n"));
 951                 *gotsomewhere = 1;
 952                 return (0);
 953         }
 954         if (n < 0) {
 955                 if (errno == EINTR) {
 956                         now = evNowTime();
 957                         if (evCmpTime(finish, now) > 0) {
 958                                 timeout = evSubTime(finish, now);
 959                                 goto wait;
 960                         }
 961                 }
 962                 Perror(statp, stderr, "select", errno);
 963                 res_nclose(statp);
 964                 return (0);
 965         }
 966         __set_errno (0);
 967 #ifdef _LIBC
 968         fromlen = sizeof(struct sockaddr_in6);
 969 #else
 970         fromlen = sizeof(struct sockaddr_in);
 971 #endif
 972         resplen = recvfrom(s, (char*)ans, anssiz,0,
 973                            (struct sockaddr *)&from, &fromlen);
 974         if (resplen <= 0) {
 975                 Perror(statp, stderr, "recvfrom", errno);
 976                 res_nclose(statp);
 977                 return (0);
 978         }
 979         *gotsomewhere = 1;
 980         if (resplen < HFIXEDSZ) {
 981                 /*
 982                  * Undersized message.
 983                  */
 984                 Dprint(statp->options & RES_DEBUG,
 985                        (stdout, ";; undersized: %d\n",
 986                         resplen));
 987                 *terrno = EMSGSIZE;
 988                 res_nclose(statp);
 989                 return (0);
 990         }
 991         if (hp->id != anhp->id) {
 992                 /*
 993                  * response from old query, ignore it.
 994                  * XXX - potential security hazard could
 995                  *       be detected here.
 996                  */
 997                 DprintQ((statp->options & RES_DEBUG) ||
 998                         (statp->pfcode & RES_PRF_REPLY),
 999                         (stdout, ";; old answer:\n"),
1000                         ans, (resplen > anssiz) ? anssiz : resplen);
1001                 goto wait;
1002         }
1003         if (!(statp->options & RES_INSECURE1) &&
1004             !res_ourserver_p(statp, &from)) {
1005                 /*
1006                  * response from wrong server? ignore it.
1007                  * XXX - potential security hazard could
1008                  *       be detected here.
1009                  */
1010                 DprintQ((statp->options & RES_DEBUG) ||
1011                         (statp->pfcode & RES_PRF_REPLY),
1012                         (stdout, ";; not our server:\n"),
1013                         ans, (resplen > anssiz) ? anssiz : resplen);
1014                 goto wait;
1015         }
1016         if (!(statp->options & RES_INSECURE2) &&
1017             !res_queriesmatch(buf, buf + buflen,
1018                               ans, ans + anssiz)) {
1019                 /*
1020                  * response contains wrong query? ignore it.
1021                  * XXX - potential security hazard could
1022                  *       be detected here.
1023                  */
1024                 DprintQ((statp->options & RES_DEBUG) ||
1025                         (statp->pfcode & RES_PRF_REPLY),
1026                         (stdout, ";; wrong query name:\n"),
1027                         ans, (resplen > anssiz) ? anssiz : resplen);
1028                 goto wait;
1029         }
1030         if (anhp->rcode == SERVFAIL ||
1031             anhp->rcode == NOTIMP ||
1032             anhp->rcode == REFUSED) {
1033                 DprintQ(statp->options & RES_DEBUG,
1034                         (stdout, "server rejected query:\n"),
1035                         ans, (resplen > anssiz) ? anssiz : resplen);
1036                 res_nclose(statp);
1037                 /* don't retry if called from dig */
1038                 if (!statp->pfcode)
1039                         return (0);
1040         }
1041         if (!(statp->options & RES_IGNTC) && anhp->tc) {
1042                 /*
1043                  * To get the rest of answer,
1044                  * use TCP with same server.
1045                  */
1046                 Dprint(statp->options & RES_DEBUG,
1047                        (stdout, ";; truncated answer\n"));
1048                 *v_circuit = 1;
1049                 res_nclose(statp);
1050                 return (1);
1051         }
1052         /*
1053          * All is well, or the error is fatal.  Signal that the
1054          * next nameserver ought not be tried.
1055          */
1056         return (resplen);
1057 }
1058
1059 #ifdef DEBUG
1060 static void
1061 Aerror(const res_state statp, FILE *file, const char *string, int error,
1062        struct sockaddr_in address)
1063 {
1064         int save = errno;
1065
1066         if ((statp->options & RES_DEBUG) != 0) {
1067                 char tmp[sizeof "255.255.255.255"];
1068
1069                 fprintf(file, "res_send: %s ([%s].%u): %s\n",
1070                         string,
1071                         inet_ntop(address.sin_family, &address.sin_addr,
1072                                   tmp, sizeof tmp),
1073                         ntohs(address.sin_port),
1074                         strerror(error));
1075         }
1076         __set_errno (save);
1077 }
1078
1079 static void
1080 Perror(const res_state statp, FILE *file, const char *string, int error) {
1081         int save = errno;
1082
1083         if ((statp->options & RES_DEBUG) != 0)
1084                 fprintf(file, "res_send: %s: %s\n",
1085                         string, strerror(error));
1086         __set_errno (save);
1087 }
1088 #endif
1089
1090 static int
1091 #ifdef _LIBC
1092 sock_eq(struct sockaddr_in6 *a1, struct sockaddr_in6 *a2) {
1093         if (a1->sin6_family == a2->sin6_family) {
1094                 if (a1->sin6_family == AF_INET)
1095                         return ((((struct sockaddr_in *)a1)->sin_port ==
1096                                  ((struct sockaddr_in *)a2)->sin_port) &&
1097                                 (((struct sockaddr_in *)a1)->sin_addr.s_addr ==
1098                                  ((struct sockaddr_in *)a2)->sin_addr.s_addr));
1099                 else
1100                         return ((a1->sin6_port == a2->sin6_port) &&
1101                                 !memcmp(&a1->sin6_addr, &a2->sin6_addr,
1102                                         sizeof (struct in6_addr)));
1103         }
1104         if (a1->sin6_family == AF_INET) {
1105                 struct sockaddr_in6 *sap = a1;
1106                 a1 = a2;
1107                 a2 = sap;
1108         } /* assumes that AF_INET and AF_INET6 are the only possibilities */
1109         return ((a1->sin6_port == ((struct sockaddr_in *)a2)->sin_port) &&
1110                 IN6_IS_ADDR_V4MAPPED(&a1->sin6_addr) &&
1111                 (a1->sin6_addr.s6_addr32[3] ==
1112                  ((struct sockaddr_in *)a2)->sin_addr.s_addr));
1113 }
1114 #else
1115 sock_eq(struct sockaddr_in *a1, struct sockaddr_in *a2) {
1116         return ((a1->sin_family == a2->sin_family) &&
1117                 (a1->sin_port == a2->sin_port) &&
1118                 (a1->sin_addr.s_addr == a2->sin_addr.s_addr));
1119 }
1120 #endif
1121
1122 #ifdef _LIBC
1123 /*
1124  * Converts IPv4 family, address and port to
1125  * IPv6 family, IPv4-mapped IPv6 address and port.
1126  */
1127 static void
1128 convaddr4to6(struct sockaddr_in6 *sa)
1129 {
1130     const struct sockaddr_in sa4 = *(struct sockaddr_in *)sa;
1131
1132     sa->sin6_family = AF_INET6;
1133     sa->sin6_port = sa4.sin_port;
1134     sa->sin6_addr.s6_addr32[0] = 0;
1135     sa->sin6_addr.s6_addr32[1] = 0;
1136     sa->sin6_addr.s6_addr32[2] = htonl(0xFFFF);
1137     sa->sin6_addr.s6_addr32[3] = sa4.sin_addr.s_addr;
1138 }
1139 #endif
1140
1141 #ifdef NEED_PSELECT
1142 /* XXX needs to move to the porting library. */
1143 static int
1144 pselect(int nfds, void *rfds, void *wfds, void *efds,
1145         struct timespec *tsp, const sigset_t *sigmask)
1146 {
1147         struct timeval tv, *tvp;
1148         sigset_t sigs;
1149         int n;
1150
1151         if (tsp) {
1152                 tvp = &tv;
1153                 tv = evTimeVal(*tsp);
1154         } else
1155                 tvp = NULL;
1156         if (sigmask)
1157                 sigprocmask(SIG_SETMASK, sigmask, &sigs);
1158         n = select(nfds, rfds, wfds, efds, tvp);
1159         if (sigmask)
1160                 sigprocmask(SIG_SETMASK, &sigs, NULL);
1161         if (tsp)
1162                 *tsp = evTimeSpec(tv);
1163         return (n);
1164 }
1165 #endif