resolv/res_send.c

   1 /*
   2  * ++Copyright++ 1985, 1989, 1993
   3  * -
   4  * Copyright (c) 1985, 1989, 1993
   5  *    The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by the University of
  18  *      California, Berkeley and its contributors.
  19  * 4. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  * -
  35  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  36  *
  37  * Permission to use, copy, modify, and distribute this software for any
  38  * purpose with or without fee is hereby granted, provided that the above
  39  * copyright notice and this permission notice appear in all copies, and that
  40  * the name of Digital Equipment Corporation not be used in advertising or
  41  * publicity pertaining to distribution of the document or software without
  42  * specific, written prior permission.
  43  *
  44  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  45  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  46  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  47  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  48  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  49  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  50  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  51  * SOFTWARE.
  52  * -
  53  * --Copyright--
  54  */
  55
  56 #if defined(LIBC_SCCS) && !defined(lint)
  57 static char sccsid[] = "@(#)res_send.c  8.1 (Berkeley) 6/4/93";
  58 static char rcsid[] = "$Id$";
  59 #endif /* LIBC_SCCS and not lint */
  60
  61         /* change this to "0"
  62          * if you talk to a lot
  63          * of multi-homed SunOS
  64          * ("broken") name servers.
  65          */
  66 #define CHECK_SRVR_ADDR 1       /* XXX - should be in options.h */
  67
  68 /*
  69  * Send query to name server and wait for reply.
  70  */
  71
  72 #include <sys/param.h>
  73 #include <sys/time.h>
  74 #include <sys/socket.h>
  75 #include <sys/uio.h>
  76 #include <netinet/in.h>
  77 #include <arpa/nameser.h>
  78 #include <arpa/inet.h>
  79
  80 #include <stdio.h>
  81 #include <netdb.h>
  82 #include <errno.h>
  83 #include <resolv.h>
  84 #if defined(BSD) && (BSD >= 199306)
  85 # include <stdlib.h>
  86 # include <string.h>
  87 # include <unistd.h>
  88 #else
  89 # include "../conf/portability.h"
  90 #endif
  91
  92 #if defined(USE_OPTIONS_H)
  93 # include <../conf/options.h>
  94 #endif
  95
  96 void _res_close __P((void));
  97
  98 static int s = -1;      /* socket used for communications */
  99 static int connected = 0;       /* is the socket connected */
 100 static int vc = 0;      /* is the socket a virtual ciruit? */
 101
 102 #ifndef FD_SET
 103 /* XXX - should be in portability.h */
 104 #define NFDBITS         32
 105 #define FD_SETSIZE      32
 106 #define FD_SET(n, p)    ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
 107 #define FD_CLR(n, p)    ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
 108 #define FD_ISSET(n, p)  ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
 109 #define FD_ZERO(p)      bzero((char *)(p), sizeof(*(p)))
 110 #endif
 111
 112 #ifndef DEBUG
 113 #   define Dprint(cond, args) /*empty*/
 114 #   define DprintQ(cond, args, query, size) /*empty*/
 115 #   define Aerror(file, string, error, address) /*empty*/
 116 #   define Perror(file, string, error) /*empty*/
 117 #else
 118 #   define Dprint(cond, args) if (cond) {fprintf args;} else {}
 119 #   define DprintQ(cond, args, query, size) if (cond) {\
 120                         fprintf args;\
 121                         __fp_nquery(query, size, stdout);\
 122                 } else {}
 123     static void
 124     Aerror(file, string, error, address)
 125         FILE *file;
 126         char *string;
 127         int error;
 128         struct sockaddr_in address;
 129     {
 130         int save = errno;
 131
 132         if (_res.options & RES_DEBUG) {
 133                 fprintf(file, "res_send: %s ([%s].%u): %s\n",
 134                         string,
 135                         inet_ntoa(address.sin_addr),
 136                         ntohs(address.sin_port),
 137                         strerror(error));
 138         }
 139         errno = save;
 140     }
 141     static void
 142     Perror(file, string, error)
 143         FILE *file;
 144         char *string;
 145         int error;
 146     {
 147         int save = errno;
 148
 149         if (_res.options & RES_DEBUG) {
 150                 fprintf(file, "res_send: %s: %s\n",
 151                         string, strerror(error));
 152         }
 153         errno = save;
 154     }
 155 #endif
 156
 157 static res_send_qhook Qhook = NULL;
 158 static res_send_rhook Rhook = NULL;
 159
 160 void
 161 res_send_setqhook(hook)
 162         res_send_qhook hook;
 163 {
 164
 165         Qhook = hook;
 166 }
 167
 168 void
 169 res_send_setrhook(hook)
 170         res_send_rhook hook;
 171 {
 172
 173         Rhook = hook;
 174 }
 175
 176 /* int
 177  * res_isourserver(ina)
 178  *      looks up "ina" in _res.ns_addr_list[]
 179  * returns:
 180  *      0  : not found
 181  *      >0 : found
 182  * author:
 183  *      paul vixie, 29may94
 184  */
 185 int
 186 res_isourserver(inp)
 187         const struct sockaddr_in *inp;
 188 {
 189         struct sockaddr_in ina;
 190         register int ns, ret;
 191
 192         ina = *inp;
 193         ret = 0;
 194         for (ns = 0;  ns < _res.nscount;  ns++) {
 195                 register const struct sockaddr_in *srv = &_res.nsaddr_list[ns];
 196
 197                 if (srv->sin_family == ina.sin_family &&
 198                     srv->sin_port == ina.sin_port &&
 199                     (srv->sin_addr.s_addr == INADDR_ANY ||
 200                      srv->sin_addr.s_addr == ina.sin_addr.s_addr)) {
 201                         ret++;
 202                         break;
 203                 }
 204         }
 205         return (ret);
 206 }
 207
 208 /* int
 209  * res_nameinquery(name, type, class, buf, eom)
 210  *      look for (name,type,class) in the query section of packet (buf,eom)
 211  * returns:
 212  *      -1 : format error
 213  *      0  : not found
 214  *      >0 : found
 215  * author:
 216  *      paul vixie, 29may94
 217  */
 218 int
 219 res_nameinquery(name, type, class, buf, eom)
 220         const char *name;
 221         register int type, class;
 222         const u_char *buf, *eom;
 223 {
 224         register const u_char *cp = buf + HFIXEDSZ;
 225         int qdcount = ntohs(((HEADER*)buf)->qdcount);
 226
 227         while (qdcount-- > 0) {
 228                 char tname[MAXDNAME+1];
 229                 register int n, ttype, tclass;
 230
 231                 n = dn_expand(buf, eom, cp, tname, sizeof tname);
 232                 if (n < 0)
 233                         return (-1);
 234                 cp += n;
 235                 ttype = _getshort(cp); cp += INT16SZ;
 236                 tclass = _getshort(cp); cp += INT16SZ;
 237                 if (ttype == type &&
 238                     tclass == class &&
 239                     strcasecmp(tname, name) == 0)
 240                         return (1);
 241         }
 242         return (0);
 243 }
 244
 245 /* int
 246  * res_queriesmatch(buf1, eom1, buf2, eom2)
 247  *      is there a 1:1 mapping of (name,type,class)
 248  *      in (buf1,eom1) and (buf2,eom2)?
 249  * returns:
 250  *      -1 : format error
 251  *      0  : not a 1:1 mapping
 252  *      >0 : is a 1:1 mapping
 253  * author:
 254  *      paul vixie, 29may94
 255  */
 256 int
 257 res_queriesmatch(buf1, eom1, buf2, eom2)
 258         const u_char *buf1, *eom1;
 259         const u_char *buf2, *eom2;
 260 {
 261         register const u_char *cp = buf1 + HFIXEDSZ;
 262         int qdcount = ntohs(((HEADER*)buf1)->qdcount);
 263
 264         if (qdcount != ntohs(((HEADER*)buf2)->qdcount))
 265                 return (0);
 266         while (qdcount-- > 0) {
 267                 char tname[MAXDNAME+1];
 268                 register int n, ttype, tclass;
 269
 270                 n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
 271                 if (n < 0)
 272                         return (-1);
 273                 cp += n;
 274                 ttype = _getshort(cp);  cp += INT16SZ;
 275                 tclass = _getshort(cp); cp += INT16SZ;
 276                 if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))
 277                         return (0);
 278         }
 279         return (1);
 280 }
 281
 282 int
 283 res_send(buf, buflen, ans, anssiz)
 284         const u_char *buf;
 285         int buflen;
 286         u_char *ans;
 287         int anssiz;
 288 {
 289         HEADER *hp = (HEADER *) buf;
 290         HEADER *anhp = (HEADER *) ans;
 291         int gotsomewhere, connreset, terrno, try, v_circuit, resplen, ns;
 292         register int n;
 293         u_int badns;    /* XXX NSMAX can't exceed #/bits in this var */
 294
 295         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 296                 /* errno should have been set by res_init() in this case. */
 297                 return (-1);
 298         }
 299         DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_QUERY),
 300                 (stdout, ";; res_send()\n"), buf, buflen);
 301         v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
 302         gotsomewhere = 0;
 303         connreset = 0;
 304         terrno = ETIMEDOUT;
 305         badns = 0;
 306
 307         /*
 308          * Send request, RETRY times, or until successful
 309          */
 310         for (try = 0; try < _res.retry; try++) {
 311             for (ns = 0; ns < _res.nscount; ns++) {
 312                 struct sockaddr_in *nsap = &_res.nsaddr_list[ns];
 313     same_ns:
 314                 if (badns & (1 << ns)) {
 315                         _res_close();
 316                         goto next_ns;
 317                 }
 318
 319                 if (Qhook) {
 320                         int done = 0, loops = 0;
 321
 322                         do {
 323                                 res_sendhookact act;
 324
 325                                 act = (*Qhook)(&nsap, &buf, &buflen,
 326                                                ans, anssiz, &resplen);
 327                                 switch (act) {
 328                                 case res_goahead:
 329                                         done = 1;
 330                                         break;
 331                                 case res_nextns:
 332                                         _res_close();
 333                                         goto next_ns;
 334                                 case res_done:
 335                                         return (resplen);
 336                                 case res_modified:
 337                                         /* give the hook another try */
 338                                         if (++loops < 42) /*doug adams*/
 339                                                 break;
 340                                         /*FALLTHROUGH*/
 341                                 case res_error:
 342                                         /*FALLTHROUGH*/
 343                                 default:
 344                                         return (-1);
 345                                 }
 346                         } while (!done);
 347                 }
 348
 349                 Dprint(_res.options & RES_DEBUG,
 350                        (stdout, ";; Querying server (# %d) address = %s\n",
 351                         ns + 1, inet_ntoa(nsap->sin_addr)));
 352
 353                 if (v_circuit) {
 354                         int truncated;
 355                         struct iovec iov[2];
 356                         u_short len;
 357                         u_char *cp;
 358
 359                         /*
 360                          * Use virtual circuit;
 361                          * at most one attempt per server.
 362                          */
 363                         try = _res.retry;
 364                         truncated = 0;
 365                         if ((s < 0) || (!vc)) {
 366                                 if (s >= 0)
 367                                         _res_close();
 368
 369                                 s = socket(PF_INET, SOCK_STREAM, 0);
 370                                 if (s < 0) {
 371                                         terrno = errno;
 372                                         Perror(stderr, "socket(vc)", errno);
 373                                         return (-1);
 374                                 }
 375                                 errno = 0;
 376                                 if (connect(s, (struct sockaddr *)nsap,
 377                                             sizeof(struct sockaddr)) < 0) {
 378                                         terrno = errno;
 379                                         Aerror(stderr, "connect/vc",
 380                                                errno, *nsap);
 381                                         badns |= (1 << ns);
 382                                         _res_close();
 383                                         goto next_ns;
 384                                 }
 385                                 vc = 1;
 386                         }
 387                         /*
 388                          * Send length & message
 389                          */
 390                         putshort((u_short)buflen, (u_char*)&len);
 391                         iov[0].iov_base = (caddr_t)&len;
 392                         iov[0].iov_len = INT16SZ;
 393                         iov[1].iov_base = (caddr_t)buf;
 394                         iov[1].iov_len = buflen;
 395                         if (writev(s, iov, 2) != (INT16SZ + buflen)) {
 396                                 terrno = errno;
 397                                 Perror(stderr, "write failed", errno);
 398                                 badns |= (1 << ns);
 399                                 _res_close();
 400                                 goto next_ns;
 401                         }
 402                         /*
 403                          * Receive length & response
 404                          */
 405                         cp = ans;
 406                         len = INT16SZ;
 407                         while ((n = read(s, (char *)cp, (int)len)) > 0) {
 408                                 cp += n;
 409                                 if ((len -= n) <= 0)
 410                                         break;
 411                         }
 412                         if (n <= 0) {
 413                                 terrno = errno;
 414                                 Perror(stderr, "read failed", errno);
 415                                 _res_close();
 416                                 /*
 417                                  * A long running process might get its TCP
 418                                  * connection reset if the remote server was
 419                                  * restarted.  Requery the server instead of
 420                                  * trying a new one.  When there is only one
 421                                  * server, this means that a query might work
 422                                  * instead of failing.  We only allow one reset
 423                                  * per query to prevent looping.
 424                                  */
 425                                 if (terrno == ECONNRESET && !connreset) {
 426                                         connreset = 1;
 427                                         _res_close();
 428                                         goto same_ns;
 429                                 }
 430                                 _res_close();
 431                                 goto next_ns;
 432                         }
 433                         resplen = _getshort(ans);
 434                         if (resplen > anssiz) {
 435                                 Dprint(_res.options & RES_DEBUG,
 436                                        (stdout, ";; response truncated\n")
 437                                        );
 438                                 truncated = 1;
 439                                 len = anssiz;
 440                         } else
 441                                 len = resplen;
 442                         cp = ans;
 443                         while (len != 0 &&
 444                                (n = read(s, (char *)cp, (int)len)) > 0) {
 445                                 cp += n;
 446                                 len -= n;
 447                         }
 448                         if (n <= 0) {
 449                                 terrno = errno;
 450                                 Perror(stderr, "read(vc)", errno);
 451                                 _res_close();
 452                                 goto next_ns;
 453                         }
 454                         if (truncated) {
 455                                 /*
 456                                  * Flush rest of answer
 457                                  * so connection stays in synch.
 458                                  */
 459                                 anhp->tc = 1;
 460                                 len = resplen - anssiz;
 461                                 while (len != 0) {
 462                                         char junk[PACKETSZ];
 463
 464                                         n = (len > sizeof(junk)
 465                                              ? sizeof(junk)
 466                                              : len);
 467                                         if ((n = read(s, junk, n)) > 0)
 468                                                 len -= n;
 469                                         else
 470                                                 break;
 471                                 }
 472                         }
 473                 } else {
 474                         /*
 475                          * Use datagrams.
 476                          */
 477                         struct timeval timeout;
 478                         fd_set dsmask;
 479                         struct sockaddr_in from;
 480                         int fromlen;
 481
 482                         if ((s < 0) || vc) {
 483                                 if (vc)
 484                                         _res_close();
 485                                 s = socket(PF_INET, SOCK_DGRAM, 0);
 486                                 if (s < 0) {
 487 #if !defined(BSD) || (BSD < 199103)
 488  bad_dg_sock:
 489 #endif
 490                                         terrno = errno;
 491                                         Perror(stderr, "socket(dg)", errno);
 492                                         return (-1);
 493                                 }
 494                                 connected = 0;
 495                         }
 496                         /*
 497                          * On a 4.3BSD+ machine (client and server,
 498                          * actually), sending to a nameserver datagram
 499                          * port with no nameserver will cause an
 500                          * ICMP port unreachable message to be returned.
 501                          * If our datagram socket is "connected" to the
 502                          * server, we get an ECONNREFUSED error on the next
 503                          * socket operation, and select returns if the
 504                          * error message is received.  We can thus detect
 505                          * the absence of a nameserver without timing out.
 506                          * If we have sent queries to at least two servers,
 507                          * however, we don't want to remain connected,
 508                          * as we wish to receive answers from the first
 509                          * server to respond.
 510                          */
 511                         if (_res.nscount == 1 || (try == 0 && ns == 0)) {
 512                                 /*
 513                                  * Connect only if we are sure we won't
 514                                  * receive a response from another server.
 515                                  */
 516                                 if (!connected) {
 517                                         if (connect(s, (struct sockaddr *)nsap,
 518                                                     sizeof(struct sockaddr)
 519                                                     ) < 0) {
 520                                                 Aerror(stderr,
 521                                                        "connect(dg)",
 522                                                        errno, *nsap);
 523                                                 badns |= (1 << ns);
 524                                                 _res_close();
 525                                                 goto next_ns;
 526                                         }
 527                                         connected = 1;
 528                                 }
 529                                 if (send(s, (char*)buf, buflen, 0) != buflen) {
 530                                         Perror(stderr, "send", errno);
 531                                         badns |= (1 << ns);
 532                                         _res_close();
 533                                         goto next_ns;
 534                                 }
 535                         } else {
 536                                 /*
 537                                  * Disconnect if we want to listen
 538                                  * for responses from more than one server.
 539                                  */
 540                                 if (connected) {
 541 #if defined(BSD) && (BSD >= 199103)
 542                                         struct sockaddr_in no_addr;
 543
 544                                         no_addr.sin_family = AF_INET;
 545                                         no_addr.sin_addr.s_addr = INADDR_ANY;
 546                                         no_addr.sin_port = 0;
 547                                         (void) connect(s,
 548                                                        (struct sockaddr *)
 549                                                         &no_addr,
 550                                                        sizeof(no_addr));
 551 #else
 552                                         int s1 = socket(PF_INET, SOCK_DGRAM,0);
 553                                         if (s1 < 0)
 554                                                 goto bad_dg_sock;
 555                                         (void) dup2(s1, s);
 556                                         (void) close(s1);
 557                                         Dprint(_res.options & RES_DEBUG,
 558                                                (stdout, ";; new DG socket\n"))
 559 #endif
 560                                         connected = 0;
 561                                         errno = 0;
 562                                 }
 563                                 if (sendto(s, (char*)buf, buflen, 0,
 564                                            (struct sockaddr *)nsap,
 565                                            sizeof(struct sockaddr))
 566                                     != buflen) {
 567                                         Aerror(stderr, "sendto", errno, *nsap);
 568                                         badns |= (1 << ns);
 569                                         _res_close();
 570                                         goto next_ns;
 571                                 }
 572                         }
 573
 574                         /*
 575                          * Wait for reply
 576                          */
 577                         timeout.tv_sec = (_res.retrans << try);
 578                         if (try > 0)
 579                                 timeout.tv_sec /= _res.nscount;
 580                         if ((long) timeout.tv_sec <= 0)
 581                                 timeout.tv_sec = 1;
 582                         timeout.tv_usec = 0;
 583     wait:
 584                         FD_ZERO(&dsmask);
 585                         FD_SET(s, &dsmask);
 586                         n = select(s+1, &dsmask, (fd_set *)NULL,
 587                                    (fd_set *)NULL, &timeout);
 588                         if (n < 0) {
 589                                 Perror(stderr, "select", errno);
 590                                 _res_close();
 591                                 goto next_ns;
 592                         }
 593                         if (n == 0) {
 594                                 /*
 595                                  * timeout
 596                                  */
 597                                 Dprint(_res.options & RES_DEBUG,
 598                                        (stdout, ";; timeout\n"));
 599                                 gotsomewhere = 1;
 600                                 _res_close();
 601                                 goto next_ns;
 602                         }
 603                         errno = 0;
 604                         fromlen = sizeof(struct sockaddr_in);
 605                         resplen = recvfrom(s, (char*)ans, anssiz, 0,
 606                                            (struct sockaddr *)&from, &fromlen);
 607                         if (resplen <= 0) {
 608                                 Perror(stderr, "recvfrom", errno);
 609                                 _res_close();
 610                                 goto next_ns;
 611                         }
 612                         gotsomewhere = 1;
 613                         if (hp->id != anhp->id) {
 614                                 /*
 615                                  * response from old query, ignore it.
 616                                  * XXX - potential security hazard could
 617                                  *       be detected here.
 618                                  */
 619                                 DprintQ((_res.options & RES_DEBUG) ||
 620                                         (_res.pfcode & RES_PRF_REPLY),
 621                                         (stdout, ";; old answer:\n"),
 622                                         ans, resplen);
 623                                 goto wait;
 624                         }
 625 #if CHECK_SRVR_ADDR
 626                         if (!(_res.options & RES_INSECURE1) &&
 627                             !res_isourserver(&from)) {
 628                                 /*
 629                                  * response from wrong server? ignore it.
 630                                  * XXX - potential security hazard could
 631                                  *       be detected here.
 632                                  */
 633                                 DprintQ((_res.options & RES_DEBUG) ||
 634                                         (_res.pfcode & RES_PRF_REPLY),
 635                                         (stdout, ";; not our server:\n"),
 636                                         ans, resplen);
 637                                 goto wait;
 638                         }
 639 #endif
 640                         if (!(_res.options & RES_INSECURE2) &&
 641                             !res_queriesmatch(buf, buf + buflen,
 642                                               ans, ans + anssiz)) {
 643                                 /*
 644                                  * response contains wrong query? ignore it.
 645                                  * XXX - potential security hazard could
 646                                  *       be detected here.
 647                                  */
 648                                 DprintQ((_res.options & RES_DEBUG) ||
 649                                         (_res.pfcode & RES_PRF_REPLY),
 650                                         (stdout, ";; wrong query name:\n"),
 651                                         ans, resplen);
 652                                 goto wait;
 653                         }
 654                         if (anhp->rcode == SERVFAIL ||
 655                             anhp->rcode == NOTIMP ||
 656                             anhp->rcode == REFUSED) {
 657                                 DprintQ(_res.options & RES_DEBUG,
 658                                         (stdout, "server rejected query:\n"),
 659                                         ans, resplen);
 660                                 badns |= (1 << ns);
 661                                 _res_close();
 662                                 /* don't retry if called from dig */
 663                                 if (!_res.pfcode)
 664                                         goto next_ns;
 665                         }
 666                         if (!(_res.options & RES_IGNTC) && anhp->tc) {
 667                                 /*
 668                                  * get rest of answer;
 669                                  * use TCP with same server.
 670                                  */
 671                                 Dprint(_res.options & RES_DEBUG,
 672                                        (stdout, ";; truncated answer\n"));
 673                                 v_circuit = 1;
 674                                 _res_close();
 675                                 goto same_ns;
 676                         }
 677                 } /*if vc/dg*/
 678                 DprintQ((_res.options & RES_DEBUG) ||
 679                         (_res.pfcode & RES_PRF_REPLY),
 680                         (stdout, ";; got answer:\n"),
 681                         ans, resplen);
 682                 /*
 683                  * If using virtual circuits, we assume that the first server
 684                  * is preferred over the rest (i.e. it is on the local
 685                  * machine) and only keep that one open.
 686                  * If we have temporarily opened a virtual circuit,
 687                  * or if we haven't been asked to keep a socket open,
 688                  * close the socket.
 689                  */
 690                 if ((v_circuit && (!(_res.options & RES_USEVC) || ns != 0)) ||
 691                     !(_res.options & RES_STAYOPEN)) {
 692                         _res_close();
 693                 }
 694                 if (Rhook) {
 695                         int done = 0, loops = 0;
 696
 697                         do {
 698                                 res_sendhookact act;
 699
 700                                 act = (*Rhook)(nsap, buf, buflen,
 701                                                ans, anssiz, &resplen);
 702                                 switch (act) {
 703                                 case res_goahead:
 704                                 case res_done:
 705                                         done = 1;
 706                                         break;
 707                                 case res_nextns:
 708                                         _res_close();
 709                                         goto next_ns;
 710                                 case res_modified:
 711                                         /* give the hook another try */
 712                                         if (++loops < 42) /*doug adams*/
 713                                                 break;
 714                                         /*FALLTHROUGH*/
 715                                 case res_error:
 716                                         /*FALLTHROUGH*/
 717                                 default:
 718                                         return (-1);
 719                                 }
 720                         } while (!done);
 721
 722                 }
 723                 return (resplen);
 724     next_ns: ;
 725            } /*foreach ns*/
 726         } /*foreach retry*/
 727         _res_close();
 728         if (!v_circuit)
 729                 if (!gotsomewhere)
 730                         errno = ECONNREFUSED;   /* no nameservers found */
 731                 else
 732                         errno = ETIMEDOUT;      /* no answer obtained */
 733         else
 734                 errno = terrno;
 735         return (-1);
 736 }
 737
 738 /*
 739  * This routine is for closing the socket if a virtual circuit is used and
 740  * the program wants to close it.  This provides support for endhostent()
 741  * which expects to close the socket.
 742  *
 743  * This routine is not expected to be user visible.
 744  */
 745 void
 746 _res_close()
 747 {
 748         if (s >= 0) {
 749                 (void) close(s);
 750                 s = -1;
 751                 connected = 0;
 752                 vc = 0;
 753         }
 754 }