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/time.h>
  75 #include <sys/socket.h>
  76 #include <sys/uio.h>
  77 #include <netinet/in.h>
  78 #include <arpa/nameser.h>
  79 #include <arpa/inet.h>
  80
  81 #include <stdio.h>
  82 #include <netdb.h>
  83 #include <errno.h>
  84 #include <resolv.h>
  85 #if defined(BSD) && (BSD >= 199306)
  86 # include <stdlib.h>
  87 # include <string.h>
  88 # include <unistd.h>
  89 #else
  90 # include "../conf/portability.h"
  91 #endif
  92
  93 #if defined(USE_OPTIONS_H)
  94 # include <../conf/options.h>
  95 #endif
  96
  97 static int s = -1;      /* socket used for communications */
  98 static int connected = 0;       /* is the socket connected */
  99 static int vc = 0;      /* is the socket a virtual circuit? */
 100
 101 #ifndef FD_SET
 102 /* XXX - should be in portability.h */
 103 #define NFDBITS         32
 104 #define FD_SETSIZE      32
 105 #define FD_SET(n, p)    ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
 106 #define FD_CLR(n, p)    ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
 107 #define FD_ISSET(n, p)  ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
 108 #define FD_ZERO(p)      bzero((char *)(p), sizeof(*(p)))
 109 #endif
 110
 111 /* XXX - this should be done in portability.h */
 112 #if (defined(BSD) && (BSD >= 199103)) || defined(linux)
 113 # define CAN_RECONNECT 1
 114 #else
 115 # define CAN_RECONNECT 0
 116 #endif
 117
 118 #ifndef DEBUG
 119 #   define Dprint(cond, args) /*empty*/
 120 #   define DprintQ(cond, args, query, size) /*empty*/
 121 #   define Aerror(file, string, error, address) /*empty*/
 122 #   define Perror(file, string, error) /*empty*/
 123 #else
 124 #   define Dprint(cond, args) if (cond) {fprintf args;} else {}
 125 #   define DprintQ(cond, args, query, size) if (cond) {\
 126                         fprintf args;\
 127                         __fp_nquery(query, size, stdout);\
 128                 } else {}
 129     static void
 130     Aerror(file, string, error, address)
 131         FILE *file;
 132         char *string;
 133         int error;
 134         struct sockaddr_in address;
 135     {
 136         int save = errno;
 137
 138         if (_res.options & RES_DEBUG) {
 139                 fprintf(file, "res_send: %s ([%s].%u): %s\n",
 140                         string,
 141                         inet_ntoa(address.sin_addr),
 142                         ntohs(address.sin_port),
 143                         strerror(error));
 144         }
 145         __set_errno (save);
 146     }
 147     static void
 148     Perror(file, string, error)
 149         FILE *file;
 150         char *string;
 151         int error;
 152     {
 153         int save = errno;
 154
 155         if (_res.options & RES_DEBUG) {
 156                 fprintf(file, "res_send: %s: %s\n",
 157                         string, strerror(error));
 158         }
 159         __set_errno (save);
 160     }
 161 #endif
 162
 163 static res_send_qhook Qhook = NULL;
 164 static res_send_rhook Rhook = NULL;
 165
 166 void
 167 res_send_setqhook(hook)
 168         res_send_qhook hook;
 169 {
 170
 171         Qhook = hook;
 172 }
 173
 174 void
 175 res_send_setrhook(hook)
 176         res_send_rhook hook;
 177 {
 178
 179         Rhook = hook;
 180 }
 181
 182 /* int
 183  * res_isourserver(ina)
 184  *      looks up "ina" in _res.ns_addr_list[]
 185  * returns:
 186  *      0  : not found
 187  *      >0 : found
 188  * author:
 189  *      paul vixie, 29may94
 190  */
 191 int
 192 res_isourserver(inp)
 193         const struct sockaddr_in *inp;
 194 {
 195         struct sockaddr_in ina;
 196         register int ns, ret;
 197
 198         ina = *inp;
 199         ret = 0;
 200         for (ns = 0;  ns < _res.nscount;  ns++) {
 201                 register const struct sockaddr_in *srv = &_res.nsaddr_list[ns];
 202
 203                 if (srv->sin_family == ina.sin_family &&
 204                     srv->sin_port == ina.sin_port &&
 205                     (srv->sin_addr.s_addr == INADDR_ANY ||
 206                      srv->sin_addr.s_addr == ina.sin_addr.s_addr)) {
 207                         ret++;
 208                         break;
 209                 }
 210         }
 211         return (ret);
 212 }
 213
 214 /* int
 215  * res_nameinquery(name, type, class, buf, eom)
 216  *      look for (name,type,class) in the query section of packet (buf,eom)
 217  * returns:
 218  *      -1 : format error
 219  *      0  : not found
 220  *      >0 : found
 221  * author:
 222  *      paul vixie, 29may94
 223  */
 224 int
 225 res_nameinquery(name, type, class, buf, eom)
 226         const char *name;
 227         register int type, class;
 228         const u_char *buf, *eom;
 229 {
 230         register const u_char *cp = buf + HFIXEDSZ;
 231         int qdcount = ntohs(((HEADER*)buf)->qdcount);
 232
 233         while (qdcount-- > 0) {
 234                 char tname[MAXDNAME+1];
 235                 register int n, ttype, tclass;
 236
 237                 n = dn_expand(buf, eom, cp, tname, sizeof tname);
 238                 if (n < 0)
 239                         return (-1);
 240                 cp += n;
 241                 ttype = _getshort(cp); cp += INT16SZ;
 242                 tclass = _getshort(cp); cp += INT16SZ;
 243                 if (ttype == type &&
 244                     tclass == class &&
 245                     strcasecmp(tname, name) == 0)
 246                         return (1);
 247         }
 248         return (0);
 249 }
 250
 251 /* int
 252  * res_queriesmatch(buf1, eom1, buf2, eom2)
 253  *      is there a 1:1 mapping of (name,type,class)
 254  *      in (buf1,eom1) and (buf2,eom2)?
 255  * returns:
 256  *      -1 : format error
 257  *      0  : not a 1:1 mapping
 258  *      >0 : is a 1:1 mapping
 259  * author:
 260  *      paul vixie, 29may94
 261  */
 262 int
 263 res_queriesmatch(buf1, eom1, buf2, eom2)
 264         const u_char *buf1, *eom1;
 265         const u_char *buf2, *eom2;
 266 {
 267         register const u_char *cp = buf1 + HFIXEDSZ;
 268         int qdcount = ntohs(((HEADER*)buf1)->qdcount);
 269
 270         if (qdcount != ntohs(((HEADER*)buf2)->qdcount))
 271                 return (0);
 272         while (qdcount-- > 0) {
 273                 char tname[MAXDNAME+1];
 274                 register int n, ttype, tclass;
 275
 276                 n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
 277                 if (n < 0)
 278                         return (-1);
 279                 cp += n;
 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         DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_QUERY),
 306                 (stdout, ";; res_send()\n"), buf, buflen);
 307         v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
 308         gotsomewhere = 0;
 309         connreset = 0;
 310         terrno = ETIMEDOUT;
 311         badns = 0;
 312
 313         /*
 314          * Send request, RETRY times, or until successful
 315          */
 316         for (try = 0; try < _res.retry; try++) {
 317             for (ns = 0; ns < _res.nscount; ns++) {
 318                 struct sockaddr_in *nsap = &_res.nsaddr_list[ns];
 319     same_ns:
 320                 if (badns & (1 << ns)) {
 321                         res_close();
 322                         goto next_ns;
 323                 }
 324
 325                 if (Qhook) {
 326                         int done = 0, loops = 0;
 327
 328                         do {
 329                                 res_sendhookact act;
 330
 331                                 act = (*Qhook)(&nsap, &buf, &buflen,
 332                                                ans, anssiz, &resplen);
 333                                 switch (act) {
 334                                 case res_goahead:
 335                                         done = 1;
 336                                         break;
 337                                 case res_nextns:
 338                                         res_close();
 339                                         goto next_ns;
 340                                 case res_done:
 341                                         return (resplen);
 342                                 case res_modified:
 343                                         /* give the hook another try */
 344                                         if (++loops < 42) /*doug adams*/
 345                                                 break;
 346                                         /*FALLTHROUGH*/
 347                                 case res_error:
 348                                         /*FALLTHROUGH*/
 349                                 default:
 350                                         return (-1);
 351                                 }
 352                         } while (!done);
 353                 }
 354
 355                 Dprint(_res.options & RES_DEBUG,
 356                        (stdout, ";; Querying server (# %d) address = %s\n",
 357                         ns + 1, inet_ntoa(nsap->sin_addr)));
 358
 359                 if (v_circuit) {
 360                         int truncated;
 361                         struct iovec iov[2];
 362                         u_short len;
 363                         u_char *cp;
 364
 365                         /*
 366                          * Use virtual circuit;
 367                          * at most one attempt per server.
 368                          */
 369                         try = _res.retry;
 370                         truncated = 0;
 371                         if ((s < 0) || (!vc)) {
 372                                 if (s >= 0)
 373                                         res_close();
 374
 375                                 s = socket(PF_INET, SOCK_STREAM, 0);
 376                                 if (s < 0) {
 377                                         terrno = errno;
 378                                         Perror(stderr, "socket(vc)", errno);
 379                                         return (-1);
 380                                 }
 381                                 __set_errno (0);
 382                                 if (connect(s, (struct sockaddr *)nsap,
 383                                             sizeof(struct sockaddr)) < 0) {
 384                                         terrno = errno;
 385                                         Aerror(stderr, "connect/vc",
 386                                                errno, *nsap);
 387                                         badns |= (1 << ns);
 388                                         res_close();
 389                                         goto next_ns;
 390                                 }
 391                                 vc = 1;
 392                         }
 393                         /*
 394                          * Send length & message
 395                          */
 396                         putshort((u_short)buflen, (u_char*)&len);
 397                         iov[0].iov_base = (caddr_t)&len;
 398                         iov[0].iov_len = INT16SZ;
 399                         iov[1].iov_base = (caddr_t)buf;
 400                         iov[1].iov_len = buflen;
 401                         if (writev(s, iov, 2) != (INT16SZ + buflen)) {
 402                                 terrno = errno;
 403                                 Perror(stderr, "write failed", errno);
 404                                 badns |= (1 << ns);
 405                                 res_close();
 406                                 goto next_ns;
 407                         }
 408                         /*
 409                          * Receive length & response
 410                          */
 411 read_len:
 412                         cp = ans;
 413                         len = INT16SZ;
 414                         while ((n = read(s, (char *)cp, (int)len)) > 0) {
 415                                 cp += n;
 416                                 if ((len -= n) <= 0)
 417                                         break;
 418                         }
 419                         if (n <= 0) {
 420                                 terrno = errno;
 421                                 Perror(stderr, "read failed", errno);
 422                                 res_close();
 423                                 /*
 424                                  * A long running process might get its TCP
 425                                  * connection reset if the remote server was
 426                                  * restarted.  Requery the server instead of
 427                                  * trying a new one.  When there is only one
 428                                  * server, this means that a query might work
 429                                  * instead of failing.  We only allow one reset
 430                                  * per query to prevent looping.
 431                                  */
 432                                 if (terrno == ECONNRESET && !connreset) {
 433                                         connreset = 1;
 434                                         res_close();
 435                                         goto same_ns;
 436                                 }
 437                                 res_close();
 438                                 goto next_ns;
 439                         }
 440                         resplen = _getshort(ans);
 441                         if (resplen > anssiz) {
 442                                 Dprint(_res.options & RES_DEBUG,
 443                                        (stdout, ";; response truncated\n")
 444                                        );
 445                                 truncated = 1;
 446                                 len = anssiz;
 447                         } else
 448                                 len = resplen;
 449                         cp = ans;
 450                         while (len != 0 &&
 451                                (n = read(s, (char *)cp, (int)len)) > 0) {
 452                                 cp += n;
 453                                 len -= n;
 454                         }
 455                         if (n <= 0) {
 456                                 terrno = errno;
 457                                 Perror(stderr, "read(vc)", errno);
 458                                 res_close();
 459                                 goto next_ns;
 460                         }
 461                         if (truncated) {
 462                                 /*
 463                                  * Flush rest of answer
 464                                  * so connection stays in synch.
 465                                  */
 466                                 anhp->tc = 1;
 467                                 len = resplen - anssiz;
 468                                 while (len != 0) {
 469                                         char junk[PACKETSZ];
 470
 471                                         n = ((size_t) len > sizeof(junk)
 472                                              ? sizeof(junk)
 473                                              : len);
 474                                         if ((n = read(s, junk, n)) > 0)
 475                                                 len -= n;
 476                                         else
 477                                                 break;
 478                                 }
 479                         }
 480                         /*
 481                          * The calling applicating has bailed out of
 482                          * a previous call and failed to arrange to have
 483                          * the circuit closed or the server has got
 484                          * itself confused. Anyway drop the packet and
 485                          * wait for the correct one.
 486                          */
 487                         if (hp->id != anhp->id) {
 488                                 DprintQ((_res.options & RES_DEBUG) ||
 489                                         (_res.pfcode & RES_PRF_REPLY),
 490                                         (stdout, ";; old answer (unexpected):\n"),
 491                                         ans, (resplen>anssiz)?anssiz:resplen);
 492                                 goto read_len;
 493                         }
 494                 } else {
 495                         /*
 496                          * Use datagrams.
 497                          */
 498                         struct timeval timeout;
 499                         fd_set dsmask;
 500                         struct sockaddr_in from;
 501                         size_t fromlen;
 502
 503                         if ((s < 0) || vc) {
 504                                 if (vc)
 505                                         res_close();
 506                                 s = socket(PF_INET, SOCK_DGRAM, 0);
 507                                 if (s < 0) {
 508 #if !CAN_RECONNECT
 509  bad_dg_sock:
 510 #endif
 511                                         terrno = errno;
 512                                         Perror(stderr, "socket(dg)", errno);
 513                                         return (-1);
 514                                 }
 515                                 connected = 0;
 516                         }
 517                         /*
 518                          * On a 4.3BSD+ machine (client and server,
 519                          * actually), sending to a nameserver datagram
 520                          * port with no nameserver will cause an
 521                          * ICMP port unreachable message to be returned.
 522                          * If our datagram socket is "connected" to the
 523                          * server, we get an ECONNREFUSED error on the next
 524                          * socket operation, and select returns if the
 525                          * error message is received.  We can thus detect
 526                          * the absence of a nameserver without timing out.
 527                          * If we have sent queries to at least two servers,
 528                          * however, we don't want to remain connected,
 529                          * as we wish to receive answers from the first
 530                          * server to respond.
 531                          */
 532                         if (_res.nscount == 1 || (try == 0 && ns == 0)) {
 533                                 /*
 534                                  * Connect only if we are sure we won't
 535                                  * receive a response from another server.
 536                                  */
 537                                 if (!connected) {
 538                                         if (connect(s, (struct sockaddr *)nsap,
 539                                                     sizeof(struct sockaddr)
 540                                                     ) < 0) {
 541                                                 Aerror(stderr,
 542                                                        "connect(dg)",
 543                                                        errno, *nsap);
 544                                                 badns |= (1 << ns);
 545                                                 res_close();
 546                                                 goto next_ns;
 547                                         }
 548                                         connected = 1;
 549                                 }
 550                                 if (send(s, (char*)buf, buflen, 0) != buflen) {
 551                                         Perror(stderr, "send", errno);
 552                                         badns |= (1 << ns);
 553                                         res_close();
 554                                         goto next_ns;
 555                                 }
 556                         } else {
 557                                 /*
 558                                  * Disconnect if we want to listen
 559                                  * for responses from more than one server.
 560                                  */
 561                                 if (connected) {
 562 #if CAN_RECONNECT
 563                                         struct sockaddr_in no_addr;
 564
 565                                         no_addr.sin_family = AF_INET;
 566                                         no_addr.sin_addr.s_addr = INADDR_ANY;
 567                                         no_addr.sin_port = 0;
 568                                         (void) connect(s,
 569                                                        (struct sockaddr *)
 570                                                         &no_addr,
 571                                                        sizeof(no_addr));
 572 #else
 573                                         int s1 = socket(PF_INET, SOCK_DGRAM,0);
 574                                         if (s1 < 0)
 575                                                 goto bad_dg_sock;
 576                                         (void) dup2(s1, s);
 577                                         (void) close(s1);
 578                                         Dprint(_res.options & RES_DEBUG,
 579                                                (stdout, ";; new DG socket\n"))
 580 #endif
 581                                         connected = 0;
 582                                         __set_errno (0);
 583                                 }
 584                                 if (sendto(s, (char*)buf, buflen, 0,
 585                                            (struct sockaddr *)nsap,
 586                                            sizeof(struct sockaddr))
 587                                     != buflen) {
 588                                         Aerror(stderr, "sendto", errno, *nsap);
 589                                         badns |= (1 << ns);
 590                                         res_close();
 591                                         goto next_ns;
 592                                 }
 593                         }
 594
 595                         /*
 596                          * Wait for reply
 597                          */
 598                         timeout.tv_sec = (_res.retrans << try);
 599                         if (try > 0)
 600                                 timeout.tv_sec /= _res.nscount;
 601                         if ((long) timeout.tv_sec <= 0)
 602                                 timeout.tv_sec = 1;
 603                         timeout.tv_usec = 0;
 604                         if (s+1 > FD_SETSIZE) {
 605                                 Perror(stderr, "s+1 > FD_SETSIZE", EMFILE);
 606                                 res_close();
 607                                 goto next_ns;
 608                         }
 609     wait:
 610                         FD_ZERO(&dsmask);
 611                         FD_SET(s, &dsmask);
 612                         n = select(s+1, &dsmask, (fd_set *)NULL,
 613                                    (fd_set *)NULL, &timeout);
 614                         if (n < 0) {
 615                                 if (errno == EINTR)
 616                                         goto wait;
 617                                 Perror(stderr, "select", errno);
 618                                 res_close();
 619                                 goto next_ns;
 620                         }
 621                         if (n == 0) {
 622                                 /*
 623                                  * timeout
 624                                  */
 625                                 Dprint(_res.options & RES_DEBUG,
 626                                        (stdout, ";; timeout\n"));
 627                                 gotsomewhere = 1;
 628                                 res_close();
 629                                 goto next_ns;
 630                         }
 631                         __set_errno (0);
 632                         fromlen = sizeof(struct sockaddr_in);
 633                         resplen = recvfrom(s, (char*)ans, anssiz, 0,
 634                                            (struct sockaddr *)&from, &fromlen);
 635                         if (resplen <= 0) {
 636                                 Perror(stderr, "recvfrom", errno);
 637                                 res_close();
 638                                 goto next_ns;
 639                         }
 640                         gotsomewhere = 1;
 641                         if (hp->id != anhp->id) {
 642                                 /*
 643                                  * response from old query, ignore it.
 644                                  * XXX - potential security hazard could
 645                                  *       be detected here.
 646                                  */
 647                                 DprintQ((_res.options & RES_DEBUG) ||
 648                                         (_res.pfcode & RES_PRF_REPLY),
 649                                         (stdout, ";; old answer:\n"),
 650                                         ans, (resplen>anssiz)?anssiz:resplen);
 651                                 goto wait;
 652                         }
 653 #if CHECK_SRVR_ADDR
 654                         if (!(_res.options & RES_INSECURE1) &&
 655                             !res_isourserver(&from)) {
 656                                 /*
 657                                  * response from wrong server? ignore it.
 658                                  * XXX - potential security hazard could
 659                                  *       be detected here.
 660                                  */
 661                                 DprintQ((_res.options & RES_DEBUG) ||
 662                                         (_res.pfcode & RES_PRF_REPLY),
 663                                         (stdout, ";; not our server:\n"),
 664                                         ans, (resplen>anssiz)?anssiz:resplen);
 665                                 goto wait;
 666                         }
 667 #endif
 668                         if (!(_res.options & RES_INSECURE2) &&
 669                             !res_queriesmatch(buf, buf + buflen,
 670                                               ans, ans + anssiz)) {
 671                                 /*
 672                                  * response contains wrong query? ignore it.
 673                                  * XXX - potential security hazard could
 674                                  *       be detected here.
 675                                  */
 676                                 DprintQ((_res.options & RES_DEBUG) ||
 677                                         (_res.pfcode & RES_PRF_REPLY),
 678                                         (stdout, ";; wrong query name:\n"),
 679                                         ans, (resplen>anssiz)?anssiz:resplen);
 680                                 goto wait;
 681                         }
 682                         if (anhp->rcode == SERVFAIL ||
 683                             anhp->rcode == NOTIMP ||
 684                             anhp->rcode == REFUSED) {
 685                                 DprintQ(_res.options & RES_DEBUG,
 686                                         (stdout, "server rejected query:\n"),
 687                                         ans, (resplen>anssiz)?anssiz:resplen);
 688                                 badns |= (1 << ns);
 689                                 res_close();
 690                                 /* don't retry if called from dig */
 691                                 if (!_res.pfcode)
 692                                         goto next_ns;
 693                         }
 694                         if (!(_res.options & RES_IGNTC) && anhp->tc) {
 695                                 /*
 696                                  * get rest of answer;
 697                                  * use TCP with same server.
 698                                  */
 699                                 Dprint(_res.options & RES_DEBUG,
 700                                        (stdout, ";; truncated answer\n"));
 701                                 v_circuit = 1;
 702                                 res_close();
 703                                 goto same_ns;
 704                         }
 705                 } /*if vc/dg*/
 706                 Dprint((_res.options & RES_DEBUG) ||
 707                        ((_res.pfcode & RES_PRF_REPLY) &&
 708                         (_res.pfcode & RES_PRF_HEAD1)),
 709                        (stdout, ";; got answer:\n"));
 710                 DprintQ((_res.options & RES_DEBUG) ||
 711                         (_res.pfcode & RES_PRF_REPLY),
 712                         (stdout, ""),
 713                         ans, (resplen>anssiz)?anssiz:resplen);
 714                 /*
 715                  * If using virtual circuits, we assume that the first server
 716                  * is preferred over the rest (i.e. it is on the local
 717                  * machine) and only keep that one open.
 718                  * If we have temporarily opened a virtual circuit,
 719                  * or if we haven't been asked to keep a socket open,
 720                  * close the socket.
 721                  */
 722                 if ((v_circuit && (!(_res.options & RES_USEVC) || ns != 0)) ||
 723                     !(_res.options & RES_STAYOPEN)) {
 724                         res_close();
 725                 }
 726                 if (Rhook) {
 727                         int done = 0, loops = 0;
 728
 729                         do {
 730                                 res_sendhookact act;
 731
 732                                 act = (*Rhook)(nsap, buf, buflen,
 733                                                ans, anssiz, &resplen);
 734                                 switch (act) {
 735                                 case res_goahead:
 736                                 case res_done:
 737                                         done = 1;
 738                                         break;
 739                                 case res_nextns:
 740                                         res_close();
 741                                         goto next_ns;
 742                                 case res_modified:
 743                                         /* give the hook another try */
 744                                         if (++loops < 42) /*doug adams*/
 745                                                 break;
 746                                         /*FALLTHROUGH*/
 747                                 case res_error:
 748                                         /*FALLTHROUGH*/
 749                                 default:
 750                                         return (-1);
 751                                 }
 752                         } while (!done);
 753
 754                 }
 755                 return (resplen);
 756     next_ns: ;
 757            } /*foreach ns*/
 758         } /*foreach retry*/
 759         res_close();
 760         if (!v_circuit)
 761                 if (!gotsomewhere)
 762                         __set_errno (ECONNREFUSED); /* no nameservers found */
 763                 else
 764                         __set_errno (ETIMEDOUT);    /* no answer obtained */
 765         else
 766                 __set_errno (terrno);
 767         return (-1);
 768 }
 769
 770 /*
 771  * This routine is for closing the socket if a virtual circuit is used and
 772  * the program wants to close it.  This provides support for endhostent()
 773  * which expects to close the socket.
 774  *
 775  * This routine is not expected to be user visible.
 776  */
 777 void
 778 res_close()
 779 {
 780         if (s >= 0) {
 781                 (void) close(s);
 782                 s = -1;
 783                 connected = 0;
 784                 vc = 0;
 785         }
 786 }
 787
 788 #ifdef ultrix
 789 /* ultrix 4.0 had some icky packaging in its libc.a.  alias for it here.
 790  * there is more gunk of this kind over in res_debug.c.
 791  */
 792
 793 void
 794 _res_close()
 795 {
 796         res_close();
 797 }
 798
 799 #undef res_send
 800 int
 801 res_send(buf, buflen, ans, anssiz)
 802         const u_char *buf;
 803         int buflen;
 804         u_char *ans;
 805         int anssiz;
 806 {
 807         return (__res_send(buf, buflen, ans, anssiz));
 808 }
 809 #endif /* Ultrix 4.0 hackery */