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/types.h>
  73 #include <sys/param.h>
  74 #include <sys/poll.h>
  75 #include <sys/time.h>
  76 #include <sys/socket.h>
  77 #include <sys/uio.h>
  78 #include <netinet/in.h>
  79 #include <arpa/nameser.h>
  80 #include <arpa/inet.h>
  81
  82 #include <stdio.h>
  83 #include <netdb.h>
  84 #include <errno.h>
  85 #include <resolv.h>
  86 #if defined(BSD) && (BSD >= 199306)
  87 # include <stdlib.h>
  88 # include <string.h>
  89 # include <unistd.h>
  90 #else
  91 # include "../conf/portability.h"
  92 #endif
  93
  94 #if defined(USE_OPTIONS_H)
  95 # include <../conf/options.h>
  96 #endif
  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 circuit? */
 101
 102 /* XXX - this should be done in portability.h */
 103 #if (defined(BSD) && (BSD >= 199103)) || defined(linux)
 104 # define CAN_RECONNECT 1
 105 #else
 106 # define CAN_RECONNECT 0
 107 #endif
 108
 109 #ifndef DEBUG
 110 #   define Dprint(cond, args) /*empty*/
 111 #   define DprintQ(cond, args, query, size) /*empty*/
 112 #   define Aerror(file, string, error, address) /*empty*/
 113 #   define Perror(file, string, error) /*empty*/
 114 #else
 115 #   define Dprint(cond, args) if (cond) {fprintf args;} else {}
 116 #   define DprintQ(cond, args, query, size) if (cond) {\
 117                         fprintf args;\
 118                         __fp_nquery(query, size, stdout);\
 119                 } else {}
 120     static void
 121     Aerror(file, string, error, address)
 122         FILE *file;
 123         char *string;
 124         int error;
 125         struct sockaddr_in address;
 126     {
 127         int save = errno;
 128
 129         if (_res.options & RES_DEBUG) {
 130                 fprintf(file, "res_send: %s ([%s].%u): %s\n",
 131                         string,
 132                         inet_ntoa(address.sin_addr),
 133                         ntohs(address.sin_port),
 134                         strerror(error));
 135         }
 136         __set_errno (save);
 137     }
 138     static void
 139     Perror(file, string, error)
 140         FILE *file;
 141         char *string;
 142         int error;
 143     {
 144         int save = errno;
 145
 146         if (_res.options & RES_DEBUG) {
 147                 fprintf(file, "res_send: %s: %s\n",
 148                         string, strerror(error));
 149         }
 150         __set_errno (save);
 151     }
 152 #endif
 153
 154 static res_send_qhook Qhook = NULL;
 155 static res_send_rhook Rhook = NULL;
 156
 157 void
 158 res_send_setqhook(hook)
 159         res_send_qhook hook;
 160 {
 161
 162         Qhook = hook;
 163 }
 164
 165 void
 166 res_send_setrhook(hook)
 167         res_send_rhook hook;
 168 {
 169
 170         Rhook = hook;
 171 }
 172
 173 /* int
 174  * res_isourserver(ina)
 175  *      looks up "ina" in _res.ns_addr_list[]
 176  * returns:
 177  *      0  : not found
 178  *      >0 : found
 179  * author:
 180  *      paul vixie, 29may94
 181  */
 182 int
 183 res_isourserver(inp)
 184         const struct sockaddr_in *inp;
 185 {
 186         struct sockaddr_in ina;
 187         register int ns, ret;
 188
 189         ina = *inp;
 190         ret = 0;
 191         for (ns = 0;  ns < _res.nscount;  ns++) {
 192                 register const struct sockaddr_in *srv = &_res.nsaddr_list[ns];
 193
 194                 if (srv->sin_family == ina.sin_family &&
 195                     srv->sin_port == ina.sin_port &&
 196                     (srv->sin_addr.s_addr == INADDR_ANY ||
 197                      srv->sin_addr.s_addr == ina.sin_addr.s_addr)) {
 198                         ret++;
 199                         break;
 200                 }
 201         }
 202         return (ret);
 203 }
 204
 205 /* int
 206  * res_nameinquery(name, type, class, buf, eom)
 207  *      look for (name,type,class) in the query section of packet (buf,eom)
 208  * requires:
 209  *      buf + HFIXESDZ <= eom
 210  * returns:
 211  *      -1 : format error
 212  *      0  : not found
 213  *      >0 : found
 214  * author:
 215  *      paul vixie, 29may94
 216  */
 217 int
 218 res_nameinquery(name, type, class, buf, eom)
 219         const char *name;
 220         register int type, class;
 221         const u_char *buf, *eom;
 222 {
 223         register const u_char *cp = buf + HFIXEDSZ;
 224         int qdcount = ntohs(((HEADER*)buf)->qdcount);
 225
 226         while (qdcount-- > 0) {
 227                 char tname[MAXDNAME+1];
 228                 register int n, ttype, tclass;
 229
 230                 n = dn_expand(buf, eom, cp, tname, sizeof tname);
 231                 if (n < 0)
 232                         return (-1);
 233                 cp += n;
 234                 if (cp + 2 * INT16SZ > eom)
 235                         return (-1);
 236                 ttype = _getshort(cp); cp += INT16SZ;
 237                 tclass = _getshort(cp); cp += INT16SZ;
 238                 if (ttype == type &&
 239                     tclass == class &&
 240                     strcasecmp(tname, name) == 0)
 241                         return (1);
 242         }
 243         return (0);
 244 }
 245
 246 /* int
 247  * res_queriesmatch(buf1, eom1, buf2, eom2)
 248  *      is there a 1:1 mapping of (name,type,class)
 249  *      in (buf1,eom1) and (buf2,eom2)?
 250  * returns:
 251  *      -1 : format error
 252  *      0  : not a 1:1 mapping
 253  *      >0 : is a 1:1 mapping
 254  * author:
 255  *      paul vixie, 29may94
 256  */
 257 int
 258 res_queriesmatch(buf1, eom1, buf2, eom2)
 259         const u_char *buf1, *eom1;
 260         const u_char *buf2, *eom2;
 261 {
 262         register const u_char *cp = buf1 + HFIXEDSZ;
 263         int qdcount = ntohs(((HEADER*)buf1)->qdcount);
 264
 265         if (buf1 + HFIXEDSZ > eom1 || buf2 + HFIXEDSZ > eom2)
 266                 return (-1);
 267
 268         if (qdcount != ntohs(((HEADER*)buf2)->qdcount))
 269                 return (0);
 270         while (qdcount-- > 0) {
 271                 char tname[MAXDNAME+1];
 272                 register int n, ttype, tclass;
 273
 274                 n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
 275                 if (n < 0)
 276                         return (-1);
 277                 cp += n;
 278                 if (cp + 2 * INT16SZ > eom1)
 279                         return (-1);
 280                 ttype = _getshort(cp);  cp += INT16SZ;
 281                 tclass = _getshort(cp); cp += INT16SZ;
 282                 if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))
 283                         return (0);
 284         }
 285         return (1);
 286 }
 287
 288 int
 289 res_send(buf, buflen, ans, anssiz)
 290         const u_char *buf;
 291         int buflen;
 292         u_char *ans;
 293         int anssiz;
 294 {
 295         HEADER *hp = (HEADER *) buf;
 296         HEADER *anhp = (HEADER *) ans;
 297         int gotsomewhere, connreset, terrno, try, v_circuit, resplen, ns;
 298         register int n;
 299         u_int badns;    /* XXX NSMAX can't exceed #/bits in this var */
 300
 301         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 302                 /* errno should have been set by res_init() in this case. */
 303                 return (-1);
 304         }
 305         if (anssiz < HFIXEDSZ) {
 306                 __set_errno (EINVAL);
 307                 return (-1);
 308         }
 309         DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_QUERY),
 310                 (stdout, ";; res_send()\n"), buf, buflen);
 311         v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
 312         gotsomewhere = 0;
 313         connreset = 0;
 314         terrno = ETIMEDOUT;
 315         badns = 0;
 316
 317         /*
 318          * Send request, RETRY times, or until successful
 319          */
 320         for (try = 0; try < _res.retry; try++) {
 321             for (ns = 0; ns < _res.nscount; ns++) {
 322                 struct sockaddr_in *nsap = &_res.nsaddr_list[ns];
 323     same_ns:
 324                 if (badns & (1 << ns)) {
 325                         res_close();
 326                         goto next_ns;
 327                 }
 328
 329                 if (Qhook) {
 330                         int done = 0, loops = 0;
 331
 332                         do {
 333                                 res_sendhookact act;
 334
 335                                 act = (*Qhook)(&nsap, &buf, &buflen,
 336                                                ans, anssiz, &resplen);
 337                                 switch (act) {
 338                                 case res_goahead:
 339                                         done = 1;
 340                                         break;
 341                                 case res_nextns:
 342                                         res_close();
 343                                         goto next_ns;
 344                                 case res_done:
 345                                         return (resplen);
 346                                 case res_modified:
 347                                         /* give the hook another try */
 348                                         if (++loops < 42) /*doug adams*/
 349                                                 break;
 350                                         /*FALLTHROUGH*/
 351                                 case res_error:
 352                                         /*FALLTHROUGH*/
 353                                 default:
 354                                         return (-1);
 355                                 }
 356                         } while (!done);
 357                 }
 358
 359                 Dprint(_res.options & RES_DEBUG,
 360                        (stdout, ";; Querying server (# %d) address = %s\n",
 361                         ns + 1, inet_ntoa(nsap->sin_addr)));
 362
 363                 if (v_circuit) {
 364                         int truncated;
 365                         struct iovec iov[2];
 366                         u_short len;
 367                         u_char *cp;
 368
 369                         /*
 370                          * Use virtual circuit;
 371                          * at most one attempt per server.
 372                          */
 373                         try = _res.retry;
 374                         truncated = 0;
 375                         if ((s < 0) || (!vc)) {
 376                                 if (s >= 0)
 377                                         res_close();
 378
 379                                 s = socket(PF_INET, SOCK_STREAM, 0);
 380                                 if (s < 0) {
 381                                         terrno = errno;
 382                                         Perror(stderr, "socket(vc)", errno);
 383                                         return (-1);
 384                                 }
 385                                 __set_errno (0);
 386                                 if (connect(s, (struct sockaddr *)nsap,
 387                                             sizeof(struct sockaddr)) < 0) {
 388                                         terrno = errno;
 389                                         Aerror(stderr, "connect/vc",
 390                                                errno, *nsap);
 391                                         badns |= (1 << ns);
 392                                         res_close();
 393                                         goto next_ns;
 394                                 }
 395                                 vc = 1;
 396                         }
 397                         /*
 398                          * Send length & message
 399                          */
 400                         putshort((u_short)buflen, (u_char*)&len);
 401                         iov[0].iov_base = (caddr_t)&len;
 402                         iov[0].iov_len = INT16SZ;
 403                         iov[1].iov_base = (caddr_t)buf;
 404                         iov[1].iov_len = buflen;
 405                         if (writev(s, iov, 2) != (INT16SZ + buflen)) {
 406                                 terrno = errno;
 407                                 Perror(stderr, "write failed", errno);
 408                                 badns |= (1 << ns);
 409                                 res_close();
 410                                 goto next_ns;
 411                         }
 412                         /*
 413                          * Receive length & response
 414                          */
 415 read_len:
 416                         cp = ans;
 417                         len = INT16SZ;
 418                         while ((n = read(s, (char *)cp, (int)len)) > 0) {
 419                                 cp += n;
 420                                 if ((len -= n) <= 0)
 421                                         break;
 422                         }
 423                         if (n <= 0) {
 424                                 terrno = errno;
 425                                 Perror(stderr, "read failed", errno);
 426                                 res_close();
 427                                 /*
 428                                  * A long running process might get its TCP
 429                                  * connection reset if the remote server was
 430                                  * restarted.  Requery the server instead of
 431                                  * trying a new one.  When there is only one
 432                                  * server, this means that a query might work
 433                                  * instead of failing.  We only allow one reset
 434                                  * per query to prevent looping.
 435                                  */
 436                                 if (terrno == ECONNRESET && !connreset) {
 437                                         connreset = 1;
 438                                         res_close();
 439                                         goto same_ns;
 440                                 }
 441                                 res_close();
 442                                 goto next_ns;
 443                         }
 444                         resplen = _getshort(ans);
 445                         if (resplen > anssiz) {
 446                                 Dprint(_res.options & RES_DEBUG,
 447                                        (stdout, ";; response truncated\n")
 448                                        );
 449                                 truncated = 1;
 450                                 len = anssiz;
 451                         } else
 452                                 len = resplen;
 453                         if (len < HFIXEDSZ) {
 454                                 /*
 455                                  * Undersized message.
 456                                  */
 457                                 Dprint(_res.options & RES_DEBUG,
 458                                        (stdout, ";; undersized: %d\n", len));
 459                                 terrno = EMSGSIZE;
 460                                 badns |= (1 << ns);
 461                                 res_close();
 462                                 goto next_ns;
 463                         }
 464                         cp = ans;
 465                         while (len != 0 &&
 466                                (n = read(s, (char *)cp, (int)len)) > 0) {
 467                                 cp += n;
 468                                 len -= n;
 469                         }
 470                         if (n <= 0) {
 471                                 terrno = errno;
 472                                 Perror(stderr, "read(vc)", errno);
 473                                 res_close();
 474                                 goto next_ns;
 475                         }
 476                         if (truncated) {
 477                                 /*
 478                                  * Flush rest of answer
 479                                  * so connection stays in synch.
 480                                  */
 481                                 anhp->tc = 1;
 482                                 len = resplen - anssiz;
 483                                 while (len != 0) {
 484                                         char junk[PACKETSZ];
 485
 486                                         n = ((size_t) len > sizeof(junk)
 487                                              ? sizeof(junk)
 488                                              : len);
 489                                         if ((n = read(s, junk, n)) > 0)
 490                                                 len -= n;
 491                                         else
 492                                                 break;
 493                                 }
 494                         }
 495                         /*
 496                          * The calling applicating has bailed out of
 497                          * a previous call and failed to arrange to have
 498                          * the circuit closed or the server has got
 499                          * itself confused. Anyway drop the packet and
 500                          * wait for the correct one.
 501                          */
 502                         if (hp->id != anhp->id) {
 503                                 DprintQ((_res.options & RES_DEBUG) ||
 504                                         (_res.pfcode & RES_PRF_REPLY),
 505                                         (stdout, ";; old answer (unexpected):\n"),
 506                                         ans, (resplen>anssiz)?anssiz:resplen);
 507                                 goto read_len;
 508                         }
 509                 } else {
 510                         /*
 511                          * Use datagrams.
 512                          */
 513                         int timeout;
 514                         struct pollfd pfd[1];
 515                         struct sockaddr_in from;
 516                         socklen_t fromlen;
 517
 518                         if ((s < 0) || vc) {
 519                                 if (vc)
 520                                         res_close();
 521                                 s = socket(PF_INET, SOCK_DGRAM, 0);
 522                                 if (s < 0) {
 523 #if !CAN_RECONNECT
 524  bad_dg_sock:
 525 #endif
 526                                         terrno = errno;
 527                                         Perror(stderr, "socket(dg)", errno);
 528                                         return (-1);
 529                                 }
 530                                 connected = 0;
 531                         }
 532                         /*
 533                          * On a 4.3BSD+ machine (client and server,
 534                          * actually), sending to a nameserver datagram
 535                          * port with no nameserver will cause an
 536                          * ICMP port unreachable message to be returned.
 537                          * If our datagram socket is "connected" to the
 538                          * server, we get an ECONNREFUSED error on the next
 539                          * socket operation, and select returns if the
 540                          * error message is received.  We can thus detect
 541                          * the absence of a nameserver without timing out.
 542                          * If we have sent queries to at least two servers,
 543                          * however, we don't want to remain connected,
 544                          * as we wish to receive answers from the first
 545                          * server to respond.
 546                          */
 547                         if (_res.nscount == 1 || (try == 0 && ns == 0)) {
 548                                 /*
 549                                  * Connect only if we are sure we won't
 550                                  * receive a response from another server.
 551                                  */
 552                                 if (!connected) {
 553                                         if (connect(s, (struct sockaddr *)nsap,
 554                                                     sizeof(struct sockaddr)
 555                                                     ) < 0) {
 556                                                 Aerror(stderr,
 557                                                        "connect(dg)",
 558                                                        errno, *nsap);
 559                                                 badns |= (1 << ns);
 560                                                 res_close();
 561                                                 goto next_ns;
 562                                         }
 563                                         connected = 1;
 564                                 }
 565                                 if (send(s, (char*)buf, buflen, 0) != buflen) {
 566                                         Perror(stderr, "send", errno);
 567                                         badns |= (1 << ns);
 568                                         res_close();
 569                                         goto next_ns;
 570                                 }
 571                         } else {
 572                                 /*
 573                                  * Disconnect if we want to listen
 574                                  * for responses from more than one server.
 575                                  */
 576                                 if (connected) {
 577 #if CAN_RECONNECT
 578                                         struct sockaddr_in no_addr;
 579
 580                                         no_addr.sin_family = AF_INET;
 581                                         no_addr.sin_addr.s_addr = INADDR_ANY;
 582                                         no_addr.sin_port = 0;
 583                                         (void) connect(s,
 584                                                        (struct sockaddr *)
 585                                                         &no_addr,
 586                                                        sizeof(no_addr));
 587 #else
 588                                         int s1 = socket(PF_INET, SOCK_DGRAM,0);
 589                                         if (s1 < 0)
 590                                                 goto bad_dg_sock;
 591                                         (void) dup2(s1, s);
 592                                         (void) close(s1);
 593                                         Dprint(_res.options & RES_DEBUG,
 594                                                (stdout, ";; new DG socket\n"))
 595 #endif
 596                                         connected = 0;
 597                                         __set_errno (0);
 598                                 }
 599                                 if (sendto(s, (char*)buf, buflen, 0,
 600                                            (struct sockaddr *)nsap,
 601                                            sizeof(struct sockaddr))
 602                                     != buflen) {
 603                                         Aerror(stderr, "sendto", errno, *nsap);
 604                                         badns |= (1 << ns);
 605                                         res_close();
 606                                         goto next_ns;
 607                                 }
 608                         }
 609
 610                         /*
 611                          * Wait for reply
 612                          */
 613                         timeout = (_res.retrans << try) * 1000;
 614                         if (try > 0)
 615                                 timeout /= _res.nscount;
 616                         if (timeout <= 0)
 617                                 timeout = 1000;
 618     wait:
 619                         if (s < 0 || s >= FD_SETSIZE) {
 620                                 Perror(stderr, "s out-of-bounds", EMFILE);
 621                                 res_close();
 622                                 goto next_ns;
 623                         }
 624                         pfd[0].fd = s;
 625                         pfd[0].events = POLLIN;
 626                         n = __poll(pfd, 1, timeout);
 627                         if (n < 0) {
 628                                 if (errno == EINTR)
 629                                         goto wait;
 630                                 Perror(stderr, "poll", errno);
 631                                 res_close();
 632                                 goto next_ns;
 633                         }
 634                         if (n == 0) {
 635                                 /*
 636                                  * timeout
 637                                  */
 638                                 Dprint(_res.options & RES_DEBUG,
 639                                        (stdout, ";; timeout\n"));
 640                                 gotsomewhere = 1;
 641                                 res_close();
 642                                 goto next_ns;
 643                         }
 644                         __set_errno (0);
 645                         fromlen = sizeof(struct sockaddr_in);
 646                         resplen = recvfrom(s, (char*)ans, anssiz, 0,
 647                                            (struct sockaddr *)&from, &fromlen);
 648                         if (resplen <= 0) {
 649                                 Perror(stderr, "recvfrom", errno);
 650                                 res_close();
 651                                 goto next_ns;
 652                         }
 653                         gotsomewhere = 1;
 654                         if (resplen < HFIXEDSZ) {
 655                                 /*
 656                                  * Undersized message.
 657                                  */
 658                                 Dprint(_res.options & RES_DEBUG,
 659                                        (stdout, ";; undersized: %d\n",
 660                                         resplen));
 661                                 terrno = EMSGSIZE;
 662                                 badns |= (1 << ns);
 663                                 res_close();
 664                                 goto next_ns;
 665                         }
 666                         if (hp->id != anhp->id) {
 667                                 /*
 668                                  * response from old query, ignore it.
 669                                  * XXX - potential security hazard could
 670                                  *       be detected here.
 671                                  */
 672                                 DprintQ((_res.options & RES_DEBUG) ||
 673                                         (_res.pfcode & RES_PRF_REPLY),
 674                                         (stdout, ";; old answer:\n"),
 675                                         ans, (resplen>anssiz)?anssiz:resplen);
 676                                 goto wait;
 677                         }
 678 #if CHECK_SRVR_ADDR
 679                         if (!(_res.options & RES_INSECURE1) &&
 680                             !res_isourserver(&from)) {
 681                                 /*
 682                                  * response from wrong server? ignore it.
 683                                  * XXX - potential security hazard could
 684                                  *       be detected here.
 685                                  */
 686                                 DprintQ((_res.options & RES_DEBUG) ||
 687                                         (_res.pfcode & RES_PRF_REPLY),
 688                                         (stdout, ";; not our server:\n"),
 689                                         ans, (resplen>anssiz)?anssiz:resplen);
 690                                 goto wait;
 691                         }
 692 #endif
 693                         if (!(_res.options & RES_INSECURE2) &&
 694                             !res_queriesmatch(buf, buf + buflen,
 695                                               ans, ans + anssiz)) {
 696                                 /*
 697                                  * response contains wrong query? ignore it.
 698                                  * XXX - potential security hazard could
 699                                  *       be detected here.
 700                                  */
 701                                 DprintQ((_res.options & RES_DEBUG) ||
 702                                         (_res.pfcode & RES_PRF_REPLY),
 703                                         (stdout, ";; wrong query name:\n"),
 704                                         ans, (resplen>anssiz)?anssiz:resplen);
 705                                 goto wait;
 706                         }
 707                         if (anhp->rcode == SERVFAIL ||
 708                             anhp->rcode == NOTIMP ||
 709                             anhp->rcode == REFUSED) {
 710                                 DprintQ(_res.options & RES_DEBUG,
 711                                         (stdout, "server rejected query:\n"),
 712                                         ans, (resplen>anssiz)?anssiz:resplen);
 713                                 badns |= (1 << ns);
 714                                 res_close();
 715                                 /* don't retry if called from dig */
 716                                 if (!_res.pfcode)
 717                                         goto next_ns;
 718                         }
 719                         if (!(_res.options & RES_IGNTC) && anhp->tc) {
 720                                 /*
 721                                  * get rest of answer;
 722                                  * use TCP with same server.
 723                                  */
 724                                 Dprint(_res.options & RES_DEBUG,
 725                                        (stdout, ";; truncated answer\n"));
 726                                 v_circuit = 1;
 727                                 res_close();
 728                                 goto same_ns;
 729                         }
 730                 } /*if vc/dg*/
 731                 Dprint((_res.options & RES_DEBUG) ||
 732                        ((_res.pfcode & RES_PRF_REPLY) &&
 733                         (_res.pfcode & RES_PRF_HEAD1)),
 734                        (stdout, ";; got answer:\n"));
 735                 DprintQ((_res.options & RES_DEBUG) ||
 736                         (_res.pfcode & RES_PRF_REPLY),
 737                         (stdout, ""),
 738                         ans, (resplen>anssiz)?anssiz:resplen);
 739                 /*
 740                  * If using virtual circuits, we assume that the first server
 741                  * is preferred over the rest (i.e. it is on the local
 742                  * machine) and only keep that one open.
 743                  * If we have temporarily opened a virtual circuit,
 744                  * or if we haven't been asked to keep a socket open,
 745                  * close the socket.
 746                  */
 747                 if ((v_circuit && (!(_res.options & RES_USEVC) || ns != 0)) ||
 748                     !(_res.options & RES_STAYOPEN)) {
 749                         res_close();
 750                 }
 751                 if (Rhook) {
 752                         int done = 0, loops = 0;
 753
 754                         do {
 755                                 res_sendhookact act;
 756
 757                                 act = (*Rhook)(nsap, buf, buflen,
 758                                                ans, anssiz, &resplen);
 759                                 switch (act) {
 760                                 case res_goahead:
 761                                 case res_done:
 762                                         done = 1;
 763                                         break;
 764                                 case res_nextns:
 765                                         res_close();
 766                                         goto next_ns;
 767                                 case res_modified:
 768                                         /* give the hook another try */
 769                                         if (++loops < 42) /*doug adams*/
 770                                                 break;
 771                                         /*FALLTHROUGH*/
 772                                 case res_error:
 773                                         /*FALLTHROUGH*/
 774                                 default:
 775                                         return (-1);
 776                                 }
 777                         } while (!done);
 778
 779                 }
 780                 return (resplen);
 781     next_ns: ;
 782            } /*foreach ns*/
 783         } /*foreach retry*/
 784         res_close();
 785         if (!v_circuit)
 786                 if (!gotsomewhere)
 787                         __set_errno (ECONNREFUSED); /* no nameservers found */
 788                 else
 789                         __set_errno (ETIMEDOUT);    /* no answer obtained */
 790         else
 791                 __set_errno (terrno);
 792         return (-1);
 793 }
 794
 795 /*
 796  * This routine is for closing the socket if a virtual circuit is used and
 797  * the program wants to close it.  This provides support for endhostent()
 798  * which expects to close the socket.
 799  *
 800  * This routine is not expected to be user visible.
 801  */
 802 void
 803 res_close()
 804 {
 805         if (s >= 0) {
 806                 (void) close(s);
 807                 s = -1;
 808                 connected = 0;
 809                 vc = 0;
 810         }
 811 }
 812
 813 #ifdef ultrix
 814 /* ultrix 4.0 had some icky packaging in its libc.a.  alias for it here.
 815  * there is more gunk of this kind over in res_debug.c.
 816  */
 817
 818 void
 819 _res_close()
 820 {
 821         res_close();
 822 }
 823
 824 #undef res_send
 825 int
 826 res_send(buf, buflen, ans, anssiz)
 827         const u_char *buf;
 828         int buflen;
 829         u_char *ans;
 830         int anssiz;
 831 {
 832         return (__res_send(buf, buflen, ans, anssiz));
 833 }
 834 #endif /* Ultrix 4.0 hackery */