dns.subproj/res_send.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.1 (the "License").  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License.
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /*
  25  * ++Copyright++ 1985, 1989, 1993
  26  * -
  27  * Copyright (c) 1985, 1989, 1993
  28  *    The Regents of the University of California.  All rights reserved.
  29  *
  30  * Redistribution and use in source and binary forms, with or without
  31  * modification, are permitted provided that the following conditions
  32  * are met:
  33  * 1. Redistributions of source code must retain the above copyright
  34  *    notice, this list of conditions and the following disclaimer.
  35  * 2. Redistributions in binary form must reproduce the above copyright
  36  *    notice, this list of conditions and the following disclaimer in the
  37  *    documentation and/or other materials provided with the distribution.
  38  * 3. All advertising materials mentioning features or use of this software
  39  *    must display the following acknowledgement:
  40  *      This product includes software developed by the University of
  41  *      California, Berkeley and its contributors.
  42  * 4. Neither the name of the University nor the names of its contributors
  43  *    may be used to endorse or promote products derived from this software
  44  *    without specific prior written permission.
  45  *
  46  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  47  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  48  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  49  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  50  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  51  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  52  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  53  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  54  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  55  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  56  * SUCH DAMAGE.
  57  * -
  58  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  59  *
  60  * Permission to use, copy, modify, and distribute this software for any
  61  * purpose with or without fee is hereby granted, provided that the above
  62  * copyright notice and this permission notice appear in all copies, and that
  63  * the name of Digital Equipment Corporation not be used in advertising or
  64  * publicity pertaining to distribution of the document or software without
  65  * specific, written prior permission.
  66  *
  67  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  68  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  69  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  70  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  71  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  72  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  73  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  74  * SOFTWARE.
  75  * -
  76  * --Copyright--
  77  */
  78
  79 #if defined(LIBC_SCCS) && !defined(lint)
  80 static char sccsid[] = "@(#)res_send.c  8.1 (Berkeley) 6/4/93";
  81 static char rcsid[] = "$Id: res_send.c,v 1.6 2003/02/18 17:29:25 majka Exp $";
  82 #endif /* LIBC_SCCS and not lint */
  83
  84         /* change this to "0"
  85          * if you talk to a lot
  86          * of multi-homed SunOS
  87          * ("broken") name servers.
  88          */
  89 #define CHECK_SRVR_ADDR 1       /* XXX - should be in options.h */
  90
  91 /*
  92  * Send query to name server and wait for reply.
  93  */
  94
  95 #include <sys/param.h>
  96 #include <sys/time.h>
  97 #include <sys/socket.h>
  98 #include <sys/uio.h>
  99 #include <netinet/in.h>
 100 #include <arpa/inet.h>
 101 #include <ifaddrs.h>
 102 #include <net/if.h>
 103
 104 #include <stdio.h>
 105 #include <netdb.h>
 106 #include <errno.h>
 107
 108 #include "nameser8_compat.h"
 109 #include "resolv8_compat.h"
 110
 111 #if defined(BSD) && (BSD >= 199306)
 112 # include <stdlib.h>
 113 # include <string.h>
 114 # include <unistd.h>
 115 #else
 116 # include "portability.h"
 117 #endif
 118
 119 #if defined(USE_OPTIONS_H)
 120 # include "options.h"
 121 #endif
 122
 123 void _res_close __P((void));
 124
 125 static int s = -1;      /* socket used for communications */
 126 static int connected = 0;       /* is the socket connected */
 127 static int vc = 0;      /* is the socket a virtual ciruit? */
 128
 129 #ifndef FD_SET
 130 /* XXX - should be in portability.h */
 131 #define NFDBITS         32
 132 #define FD_SETSIZE      32
 133 #define FD_SET(n, p)    ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
 134 #define FD_CLR(n, p)    ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
 135 #define FD_ISSET(n, p)  ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
 136 #define FD_ZERO(p)      bzero((char *)(p), sizeof(*(p)))
 137 #endif
 138
 139 /* XXX - this should be done in portability.h */
 140 #if (defined(BSD) && (BSD >= 199103)) || defined(linux)
 141 # define CAN_RECONNECT 1
 142 #else
 143 # define CAN_RECONNECT 0
 144 #endif
 145
 146 #ifndef DEBUG
 147 #   define Dprint(cond, args) /*empty*/
 148 #   define DprintQ(cond, args, query, size) /*empty*/
 149 #   define Aerror(file, string, error, address) /*empty*/
 150 #   define Perror(file, string, error) /*empty*/
 151 #else
 152 #   define Dprint(cond, args) if (cond) {fprintf args;} else {}
 153 #   define DprintQ(cond, args, query, size) if (cond) {\
 154                         fprintf args;\
 155                         __fp_nquery(query, size, stdout);\
 156                 } else {}
 157     static void
 158     Aerror(file, string, error, address)
 159         FILE *file;
 160         char *string;
 161         int error;
 162         struct sockaddr_in address;
 163     {
 164         int save = errno;
 165
 166         if (_res.options & RES_DEBUG) {
 167                 fprintf(file, "res_send: %s ([%s].%u): %s\n",
 168                         string,
 169                         inet_ntoa(address.sin_addr),
 170                         ntohs(address.sin_port),
 171                         strerror(error));
 172         }
 173         errno = save;
 174     }
 175     static void
 176     Perror(file, string, error)
 177         FILE *file;
 178         char *string;
 179         int error;
 180     {
 181         int save = errno;
 182
 183         if (_res.options & RES_DEBUG) {
 184                 fprintf(file, "res_send: %s: %s\n",
 185                         string, strerror(error));
 186         }
 187         errno = save;
 188     }
 189 #endif
 190
 191 static res_send_qhook Qhook = NULL;
 192 static res_send_rhook Rhook = NULL;
 193
 194 void
 195 res_send_setqhook(hook)
 196         res_send_qhook hook;
 197 {
 198
 199         Qhook = hook;
 200 }
 201
 202 void
 203 res_send_setrhook(hook)
 204         res_send_rhook hook;
 205 {
 206
 207         Rhook = hook;
 208 }
 209
 210 /* int
 211  * res_isourserver(ina)
 212  *      looks up "ina" in _res.ns_addr_list[]
 213  * returns:
 214  *      0  : not found
 215  *      >0 : found
 216  * author:
 217  *      paul vixie, 29may94
 218  */
 219 int
 220 res_isourserver(inp)
 221         const struct sockaddr_in *inp;
 222 {
 223         struct sockaddr_in ina;
 224         register int ns, ret;
 225
 226         ina = *inp;
 227         ret = 0;
 228         for (ns = 0;  ns < _res.nscount;  ns++) {
 229                 register const struct sockaddr_in *srv = &_res.nsaddr_list[ns];
 230
 231                 if (srv->sin_family == ina.sin_family &&
 232                     srv->sin_port == ina.sin_port &&
 233                     (srv->sin_addr.s_addr == INADDR_ANY ||
 234                      srv->sin_addr.s_addr == ina.sin_addr.s_addr)) {
 235                         ret++;
 236                         break;
 237                 }
 238         }
 239         return (ret);
 240 }
 241
 242 /* int
 243  * res_nameinquery(name, type, class, buf, eom)
 244  *      look for (name,type,class) in the query section of packet (buf,eom)
 245  * returns:
 246  *      -1 : format error
 247  *      0  : not found
 248  *      >0 : found
 249  * author:
 250  *      paul vixie, 29may94
 251  */
 252 int
 253 res_nameinquery(name, type, class, buf, eom)
 254         const char *name;
 255         register int type, class;
 256         const u_char *buf, *eom;
 257 {
 258         register const u_char *cp = buf + HFIXEDSZ;
 259         int qdcount = ntohs(((HEADER*)buf)->qdcount);
 260
 261         while (qdcount-- > 0) {
 262                 char tname[MAXDNAME+1];
 263                 register int n, ttype, tclass;
 264
 265                 n = dn_expand(buf, eom, cp, tname, sizeof tname);
 266                 if (n < 0)
 267                         return (-1);
 268                 cp += n;
 269                 ttype = _getshort(cp); cp += INT16SZ;
 270                 tclass = _getshort(cp); cp += INT16SZ;
 271                 if (ttype == type &&
 272                     tclass == class &&
 273                     strcasecmp(tname, name) == 0)
 274                         return (1);
 275         }
 276         return (0);
 277 }
 278
 279 /* int
 280  * res_queriesmatch(buf1, eom1, buf2, eom2)
 281  *      is there a 1:1 mapping of (name,type,class)
 282  *      in (buf1,eom1) and (buf2,eom2)?
 283  * returns:
 284  *      -1 : format error
 285  *      0  : not a 1:1 mapping
 286  *      >0 : is a 1:1 mapping
 287  * author:
 288  *      paul vixie, 29may94
 289  */
 290 int
 291 res_queriesmatch(buf1, eom1, buf2, eom2)
 292         const u_char *buf1, *eom1;
 293         const u_char *buf2, *eom2;
 294 {
 295         register const u_char *cp = buf1 + HFIXEDSZ;
 296         int qdcount = ntohs(((HEADER*)buf1)->qdcount);
 297
 298         if (qdcount != ntohs(((HEADER*)buf2)->qdcount))
 299                 return (0);
 300         while (qdcount-- > 0) {
 301                 char tname[MAXDNAME+1];
 302                 register int n, ttype, tclass;
 303
 304                 n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
 305                 if (n < 0)
 306                         return (-1);
 307                 cp += n;
 308                 ttype = _getshort(cp);  cp += INT16SZ;
 309                 tclass = _getshort(cp); cp += INT16SZ;
 310                 if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))
 311                         return (0);
 312         }
 313         return (1);
 314 }
 315
 316 /* Returns whether a dns encoded name should be sent to multicast or not */
 317 static int dns_is_local_name(const u_int8_t *name)
 318 {
 319         const u_int8_t *d0 = NULL;              // Top-Level Domain
 320         const u_int8_t *d1 = NULL;              // Second-Level Domain
 321         const u_int8_t *d2 = NULL;              // etc.
 322         const u_int8_t *d3 = NULL;
 323
 324         if (name == NULL || *name == 0) return 0;
 325
 326         while (*name)
 327         {
 328                 d3 = d2;
 329                 d2 = d1;
 330                 d1 = d0;
 331                 d0 = name;
 332                 name += 1 + *name;
 333         }
 334
 335         // "local" domains need to be resolved with multicast
 336         // "local."
 337         if (d0[0] == 5 && strncasecmp((char *)d0+1, "local", 5) == 0) return 1;
 338
 339         // "local.arpa."
 340         if (d1 && d1[0] == 5 && strncasecmp((char *)d1+1, "local", 5) == 0 &&
 341                 d0[0] == 4 && strncasecmp((char *)d0+1, "arpa",  4) == 0) return 1;
 342
 343         // "local.int."
 344         if (d1 && d1[0] == 5 && strncasecmp((char *)d1+1, "local", 5) == 0 &&
 345                 d0[0] == 3 && strncasecmp((char *)d0+1, "int",   3) == 0) return 1;
 346
 347         // The network 169.254/16 is defined to be link-local,
 348         // so lookups in 254.169.in-addr.arpa. also need to be resolved with local multicast
 349         if (d3 && d3[0] == 3 && strncasecmp((char *)d3+1, "254",     3) == 0 &&
 350                 d2 && d2[0] == 3 && strncasecmp((char *)d2+1, "169",     3) == 0 &&
 351                 d1 && d1[0] == 7 && strncasecmp((char *)d1+1, "in-addr", 7) == 0 &&
 352                 d0[0] == 4 && strncasecmp((char *)d0+1, "arpa",    4) == 0) return 1;
 353
 354         return 0;
 355 }
 356
 357 #define DNS_LOCAL_DOMAIN_SERVICE_PORT   5353
 358 #define DNS_HEADER_SIZE 12
 359
 360 static const struct sockaddr_in mDNS_addr =
 361 {
 362         sizeof(mDNS_addr),
 363         AF_INET,
 364         htons(DNS_LOCAL_DOMAIN_SERVICE_PORT),
 365         {htonl(0xE00000FB)}     /* 224.0.0.251 */
 366 };
 367
 368 int
 369 res_send(buf, buflen, ans, anssiz)
 370         const u_char *buf;
 371         int buflen;
 372         u_char *ans;
 373         int anssiz;
 374 {
 375         HEADER *hp = (HEADER *) buf;
 376         HEADER *anhp = (HEADER *) ans;
 377         int gotsomewhere, connreset, terrno, try, v_circuit, resplen, ns;
 378         register int n;
 379         u_int badns;    /* XXX NSMAX can't exceed #/bits in this var */
 380         int multicast;
 381
 382         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 383                 /* errno should have been set by res_init() in this case. */
 384                 return (-1);
 385         }
 386         DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_QUERY),
 387                 (stdout, ";; res_send()\n"), buf, buflen);
 388         v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
 389         gotsomewhere = 0;
 390         connreset = 0;
 391         terrno = ETIMEDOUT;
 392         badns = 0;
 393
 394         if (dns_is_local_name((u_int8_t*)(buf + DNS_HEADER_SIZE))) {
 395                 multicast = 1;
 396                 v_circuit = 0;
 397         } else {
 398                 multicast = 0;
 399         }
 400
 401
 402         /*
 403          * Send request, RETRY times, or until successful
 404          */
 405         for (try = 0; try < _res.retry; try++) {
 406             for (ns = 0; (multicast == 0 && ns < _res.nscount) ||
 407                         (multicast == 1 && ns < 1) ; ns++) {
 408                 struct sockaddr_in *nsap;
 409                 if (multicast == 0)
 410                         nsap = &_res.nsaddr_list[ns];
 411                 else
 412                         nsap = (struct sockaddr_in*)&mDNS_addr; /* const cast */
 413     same_ns:
 414                 if (badns & (1 << ns)) {
 415                         _res_close();
 416                         goto next_ns;
 417                 }
 418
 419                 if (Qhook) {
 420                         int done = 0, loops = 0;
 421
 422                         do {
 423                                 res_sendhookact act;
 424
 425                                 act = (*Qhook)(&nsap, &buf, &buflen,
 426                                                ans, anssiz, &resplen);
 427                                 switch (act) {
 428                                 case res_goahead:
 429                                         done = 1;
 430                                         break;
 431                                 case res_nextns:
 432                                         _res_close();
 433                                         goto next_ns;
 434                                 case res_done:
 435                                         return (resplen);
 436                                 case res_modified:
 437                                         /* give the hook another try */
 438                                         if (++loops < 42) /*doug adams*/
 439                                                 break;
 440                                         /*FALLTHROUGH*/
 441                                 case res_error:
 442                                         /*FALLTHROUGH*/
 443                                 default:
 444                                         return (-1);
 445                                 }
 446                         } while (!done);
 447                 }
 448
 449                 Dprint(_res.options & RES_DEBUG,
 450                        (stdout, ";; Querying server (# %d) address = %s\n",
 451                         ns + 1, inet_ntoa(nsap->sin_addr)));
 452
 453                 if (v_circuit) {
 454                         int truncated;
 455                         struct iovec iov[2];
 456                         u_short len;
 457                         u_char *cp;
 458
 459                         /*
 460                          * Use virtual circuit;
 461                          * at most one attempt per server.
 462                          */
 463                         try = _res.retry;
 464                         truncated = 0;
 465                         if ((s < 0) || (!vc)) {
 466                                 if (s >= 0)
 467                                         _res_close();
 468
 469                                 s = socket(PF_INET, SOCK_STREAM, 0);
 470                                 if (s < 0) {
 471                                         terrno = errno;
 472                                         Perror(stderr, "socket(vc)", errno);
 473                                         return (-1);
 474                                 }
 475                                 errno = 0;
 476                                 if (connect(s, (struct sockaddr *)nsap,
 477                                             sizeof(struct sockaddr)) < 0) {
 478                                         terrno = errno;
 479                                         Aerror(stderr, "connect/vc",
 480                                                errno, *nsap);
 481                                         badns |= (1 << ns);
 482                                         _res_close();
 483                                         goto next_ns;
 484                                 }
 485                                 vc = 1;
 486                         }
 487                         /*
 488                          * Send length & message
 489                          */
 490                         putshort((u_short)buflen, (u_char*)&len);
 491                         iov[0].iov_base = (caddr_t)&len;
 492                         iov[0].iov_len = INT16SZ;
 493                         iov[1].iov_base = (caddr_t)buf;
 494                         iov[1].iov_len = buflen;
 495                         if (writev(s, iov, 2) != (INT16SZ + buflen)) {
 496                                 terrno = errno;
 497                                 Perror(stderr, "write failed", errno);
 498                                 badns |= (1 << ns);
 499                                 _res_close();
 500                                 goto next_ns;
 501                         }
 502                         /*
 503                          * Receive length & response
 504                          */
 505                         cp = ans;
 506                         len = INT16SZ;
 507                         while ((n = read(s, (char *)cp, (int)len)) > 0) {
 508                                 cp += n;
 509                                 if ((len -= n) <= 0)
 510                                         break;
 511                         }
 512                         if (n <= 0) {
 513                                 terrno = errno;
 514                                 Perror(stderr, "read failed", errno);
 515                                 _res_close();
 516                                 /*
 517                                  * A long running process might get its TCP
 518                                  * connection reset if the remote server was
 519                                  * restarted.  Requery the server instead of
 520                                  * trying a new one.  When there is only one
 521                                  * server, this means that a query might work
 522                                  * instead of failing.  We only allow one reset
 523                                  * per query to prevent looping.
 524                                  */
 525                                 if (terrno == ECONNRESET && !connreset) {
 526                                         connreset = 1;
 527                                         _res_close();
 528                                         goto same_ns;
 529                                 }
 530                                 _res_close();
 531                                 goto next_ns;
 532                         }
 533                         resplen = _getshort(ans);
 534                         if (resplen > anssiz) {
 535                                 Dprint(_res.options & RES_DEBUG,
 536                                        (stdout, ";; response truncated\n")
 537                                        );
 538                                 truncated = 1;
 539                                 len = anssiz;
 540                         } else
 541                                 len = resplen;
 542                         cp = ans;
 543                         while (len != 0 &&
 544                                (n = read(s, (char *)cp, (int)len)) > 0) {
 545                                 cp += n;
 546                                 len -= n;
 547                         }
 548                         if (n <= 0) {
 549                                 terrno = errno;
 550                                 Perror(stderr, "read(vc)", errno);
 551                                 _res_close();
 552                                 goto next_ns;
 553                         }
 554                         if (truncated) {
 555                                 /*
 556                                  * Flush rest of answer
 557                                  * so connection stays in synch.
 558                                  */
 559                                 anhp->tc = 1;
 560                                 len = resplen - anssiz;
 561                                 while (len != 0) {
 562                                         char junk[PACKETSZ];
 563
 564                                         n = (len > sizeof(junk)
 565                                              ? sizeof(junk)
 566                                              : len);
 567                                         if ((n = read(s, junk, n)) > 0)
 568                                                 len -= n;
 569                                         else
 570                                                 break;
 571                                 }
 572                         }
 573                 } else {
 574                         /*
 575                          * Use datagrams.
 576                          */
 577                         struct timeval timeout;
 578                         fd_set dsmask;
 579                         struct sockaddr_in from;
 580                         unsigned int fromlen;
 581
 582                         if ((s < 0) || vc) {
 583                                 if (vc)
 584                                         _res_close();
 585                                 s = socket(PF_INET, SOCK_DGRAM, 0);
 586                                 if (s < 0) {
 587 #if !CAN_RECONNECT
 588  bad_dg_sock:
 589 #endif
 590                                         terrno = errno;
 591                                         Perror(stderr, "socket(dg)", errno);
 592                                         return (-1);
 593                                 }
 594                                 connected = 0;
 595                         }
 596                         /*
 597                          * On a 4.3BSD+ machine (client and server,
 598                          * actually), sending to a nameserver datagram
 599                          * port with no nameserver will cause an
 600                          * ICMP port unreachable message to be returned.
 601                          * If our datagram socket is "connected" to the
 602                          * server, we get an ECONNREFUSED error on the next
 603                          * socket operation, and select returns if the
 604                          * error message is received.  We can thus detect
 605                          * the absence of a nameserver without timing out.
 606                          * If we have sent queries to at least two servers,
 607                          * however, we don't want to remain connected,
 608                          * as we wish to receive answers from the first
 609                          * server to respond.
 610                          */
 611                         if ((_res.nscount == 1 || (try == 0 && ns == 0)) && multicast == 0) {
 612                                 /*
 613                                  * Connect only if we are sure we won't
 614                                  * receive a response from another server.
 615                                  */
 616                                 if (!connected) {
 617                                         if (connect(s, (struct sockaddr *)nsap,
 618                                                     sizeof(struct sockaddr)
 619                                                     ) < 0) {
 620                                                 Aerror(stderr,
 621                                                        "connect(dg)",
 622                                                        errno, *nsap);
 623                                                 badns |= (1 << ns);
 624                                                 _res_close();
 625                                                 goto next_ns;
 626                                         }
 627                                         connected = 1;
 628                                 }
 629                                 if (send(s, (char*)buf, buflen, 0) != buflen) {
 630                                         Perror(stderr, "send", errno);
 631                                         badns |= (1 << ns);
 632                                         _res_close();
 633                                         goto next_ns;
 634                                 }
 635                         } else {
 636                                 /*
 637                                  * Disconnect if we want to listen
 638                                  * for responses from more than one server.
 639                                  */
 640                                 if (connected) {
 641 #if CAN_RECONNECT
 642                                         struct sockaddr_in no_addr;
 643
 644                                         no_addr.sin_family = AF_INET;
 645                                         no_addr.sin_addr.s_addr = INADDR_ANY;
 646                                         no_addr.sin_port = 0;
 647                                         (void) connect(s,
 648                                                        (struct sockaddr *)
 649                                                         &no_addr,
 650                                                        sizeof(no_addr));
 651 #else
 652                                         int s1 = socket(PF_INET, SOCK_DGRAM,0);
 653                                         if (s1 < 0)
 654                                                 goto bad_dg_sock;
 655                                         (void) dup2(s1, s);
 656                                         (void) close(s1);
 657                                         Dprint(_res.options & RES_DEBUG,
 658                                                (stdout, ";; new DG socket\n"))
 659 #endif
 660                                         connected = 0;
 661                                         errno = 0;
 662                                 }
 663
 664                                 if (multicast) {
 665                                         struct ifaddrs* addrs;
 666                                         struct ifaddrs* curAddr;
 667                                         const int twofivefive = 255;
 668
 669                                         // multicast packets with TTL 255
 670                                         if(setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL, &twofivefive, sizeof(twofivefive))) {
 671                                                 Perror(stderr, "setsocketopt - IP_MULTICAST_TTL", errno);
 672                                                 _res_close();
 673                                                 return (0);
 674                                         }
 675
 676                                         if (getifaddrs(&addrs) != 0)
 677                                         {
 678                                                 Perror(stderr, "getifaddrs", errno);
 679                                                 _res_close();
 680                                                 return (0);
 681                                         }
 682
 683                                         /* multicast should send request on all multicast capable interfaces */
 684                                         for (curAddr = addrs; curAddr != NULL; curAddr = curAddr->ifa_next) {
 685                                                 if ((curAddr->ifa_addr->sa_family) == AF_INET &&
 686                                                         (curAddr->ifa_flags & IFF_MULTICAST) != 0 &&
 687                                                         (curAddr->ifa_flags & IFF_POINTOPOINT) == 0) {
 688                                                         struct in_addr* if_ip_addr = &((struct sockaddr_in*)curAddr->ifa_addr)->sin_addr;
 689
 690                                                         if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF,
 691                                                                 if_ip_addr, sizeof(*if_ip_addr)) != 0) {
 692                                                                 freeifaddrs(addrs);
 693                                                                 Perror(stderr, "setsocketopt - IP_MULTICAST_IF", errno);
 694                                                                 _res_close();
 695                                                                 return (0);
 696                                                         }
 697
 698                                                         if (sendto(s, (char*)buf, buflen, 0,
 699                                                                    (struct sockaddr *)nsap, sizeof *nsap) != buflen)
 700                                                         {
 701                                                                 freeifaddrs(addrs);
 702                                                                 Aerror(stderr, "sendto", errno, *nsap);
 703                                                                 _res_close();
 704                                                                 return (0);
 705                                                         }
 706                                                 }
 707                                         }
 708
 709                                         freeifaddrs(addrs);
 710                                 } else {
 711                                         if (sendto(s, (char*)buf, buflen, 0,
 712                                                    (struct sockaddr *)nsap,
 713                                                    sizeof(struct sockaddr))
 714                                                 != buflen) {
 715                                                 Aerror(stderr, "sendto", errno, *nsap);
 716                                                 badns |= (1 << ns);
 717                                                 _res_close();
 718                                                 goto next_ns;
 719                                         }
 720                                 }
 721                         }
 722
 723                         /*
 724                          * Wait for reply
 725                          */
 726                         timeout.tv_sec = (_res.retrans << try);
 727                         if (try > 0)
 728                                 timeout.tv_sec /= _res.nscount;
 729                         if ((long) timeout.tv_sec <= 0 || multicast)
 730                                 timeout.tv_sec = 1;
 731                         timeout.tv_usec = 0;
 732     wait:
 733                         FD_ZERO(&dsmask);
 734                         FD_SET(s, &dsmask);
 735                         n = select(s+1, &dsmask, (fd_set *)NULL,
 736                                    (fd_set *)NULL, &timeout);
 737                         if (n < 0) {
 738                                 Perror(stderr, "select", errno);
 739                                 _res_close();
 740                                 goto next_ns;
 741                         }
 742                         if (n == 0) {
 743                                 /*
 744                                  * timeout
 745                                  */
 746                                 Dprint(_res.options & RES_DEBUG,
 747                                        (stdout, ";; timeout\n"));
 748                                 gotsomewhere = 1;
 749                                 _res_close();
 750                                 goto next_ns;
 751                         }
 752                         errno = 0;
 753                         fromlen = sizeof(struct sockaddr_in);
 754                         resplen = recvfrom(s, (char*)ans, anssiz, 0,
 755                                            (struct sockaddr *)&from, &fromlen);
 756                         if (resplen <= 0) {
 757                                 Perror(stderr, "recvfrom", errno);
 758                                 _res_close();
 759                                 goto next_ns;
 760                         }
 761                         gotsomewhere = 1;
 762                         if (hp->id != anhp->id) {
 763                                 /*
 764                                  * response from old query, ignore it.
 765                                  * XXX - potential security hazard could
 766                                  *       be detected here.
 767                                  */
 768                                 DprintQ((_res.options & RES_DEBUG) ||
 769                                         (_res.pfcode & RES_PRF_REPLY),
 770                                         (stdout, ";; old answer:\n"),
 771                                         ans, resplen);
 772                                 goto wait;
 773                         }
 774 #if CHECK_SRVR_ADDR
 775                         if (!(_res.options & RES_INSECURE1) &&
 776                             multicast == 0 && !res_isourserver(&from)) {
 777                                 /*
 778                                  * response from wrong server? ignore it.
 779                                  * XXX - potential security hazard could
 780                                  *       be detected here.
 781                                  */
 782                                 DprintQ((_res.options & RES_DEBUG) ||
 783                                         (_res.pfcode & RES_PRF_REPLY),
 784                                         (stdout, ";; not our server:\n"),
 785                                         ans, resplen);
 786                                 goto wait;
 787                         }
 788 #endif
 789                         if (!(_res.options & RES_INSECURE2) &&
 790                             !res_queriesmatch(buf, buf + buflen,
 791                                               ans, ans + anssiz)) {
 792                                 /*
 793                                  * response contains wrong query? ignore it.
 794                                  * XXX - potential security hazard could
 795                                  *       be detected here.
 796                                  */
 797                                 DprintQ((_res.options & RES_DEBUG) ||
 798                                         (_res.pfcode & RES_PRF_REPLY),
 799                                         (stdout, ";; wrong query name:\n"),
 800                                         ans, resplen);
 801                                 goto wait;
 802                         }
 803                         if (anhp->rcode == SERVFAIL ||
 804                             anhp->rcode == NOTIMP ||
 805                             anhp->rcode == REFUSED) {
 806                                 DprintQ(_res.options & RES_DEBUG,
 807                                         (stdout, "server rejected query:\n"),
 808                                         ans, resplen);
 809                                 badns |= (1 << ns);
 810                                 _res_close();
 811                                 /* don't retry if called from dig */
 812                                 if (!_res.pfcode)
 813                                         goto next_ns;
 814                         }
 815                         if (!(_res.options & RES_IGNTC) && anhp->tc) {
 816                                 /*
 817                                  * get rest of answer;
 818                                  * use TCP with same server.
 819                                  */
 820                                 Dprint(_res.options & RES_DEBUG,
 821                                        (stdout, ";; truncated answer\n"));
 822                                 v_circuit = 1;
 823                                 _res_close();
 824                                 goto same_ns;
 825                         }
 826                 } /*if vc/dg*/
 827                 DprintQ((_res.options & RES_DEBUG) ||
 828                         (_res.pfcode & RES_PRF_REPLY),
 829                         (stdout, ";; got answer:\n"),
 830                         ans, resplen);
 831                 /*
 832                  * If using virtual circuits, we assume that the first server
 833                  * is preferred over the rest (i.e. it is on the local
 834                  * machine) and only keep that one open.
 835                  * If we have temporarily opened a virtual circuit,
 836                  * or if we haven't been asked to keep a socket open,
 837                  * close the socket.
 838                  */
 839                 if ((v_circuit && (!(_res.options & RES_USEVC) || ns != 0)) ||
 840                     !(_res.options & RES_STAYOPEN)) {
 841                         _res_close();
 842                 }
 843                 if (Rhook) {
 844                         int done = 0, loops = 0;
 845
 846                         do {
 847                                 res_sendhookact act;
 848
 849                                 act = (*Rhook)(nsap, buf, buflen,
 850                                                ans, anssiz, &resplen);
 851                                 switch (act) {
 852                                 case res_goahead:
 853                                 case res_done:
 854                                         done = 1;
 855                                         break;
 856                                 case res_nextns:
 857                                         _res_close();
 858                                         goto next_ns;
 859                                 case res_modified:
 860                                         /* give the hook another try */
 861                                         if (++loops < 42) /*doug adams*/
 862                                                 break;
 863                                         /*FALLTHROUGH*/
 864                                 case res_error:
 865                                         /*FALLTHROUGH*/
 866                                 default:
 867                                         return (-1);
 868                                 }
 869                         } while (!done);
 870
 871                 }
 872                 return (resplen);
 873     next_ns: ;
 874            } /*foreach ns*/
 875         } /*foreach retry*/
 876         _res_close();
 877         if (!v_circuit)
 878                 if (!gotsomewhere)
 879                         errno = ECONNREFUSED;   /* no nameservers found */
 880                 else
 881                         errno = ETIMEDOUT;      /* no answer obtained */
 882         else
 883                 errno = terrno;
 884         return (-1);
 885 }
 886
 887 /*
 888  * This routine is for closing the socket if a virtual circuit is used and
 889  * the program wants to close it.  This provides support for endhostent()
 890  * which expects to close the socket.
 891  *
 892  * This routine is not expected to be user visible.
 893  */
 894 void
 895 _res_close()
 896 {
 897         if (s >= 0) {
 898                 (void) close(s);
 899                 s = -1;
 900                 connected = 0;
 901                 vc = 0;
 902         }
 903 }