resolv/res_mkquery.c

   1 /* Creation of DNS query packets.
   2    Copyright (C) 1995-2018 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 /*
  20  * Copyright (c) 1985, 1993
  21  *    The Regents of the University of California.  All rights reserved.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the above copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 4. Neither the name of the University nor the names of its contributors
  32  *    may be used to endorse or promote products derived from this software
  33  *    without specific prior written permission.
  34  *
  35  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  36  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  37  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  38  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  39  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  40  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  41  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  42  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  43  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  44  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  45  * SUCH DAMAGE.
  46  */
  47
  48 /*
  49  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  50  *
  51  * Permission to use, copy, modify, and distribute this software for any
  52  * purpose with or without fee is hereby granted, provided that the above
  53  * copyright notice and this permission notice appear in all copies, and that
  54  * the name of Digital Equipment Corporation not be used in advertising or
  55  * publicity pertaining to distribution of the document or software without
  56  * specific, written prior permission.
  57  *
  58  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  59  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  60  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  61  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  62  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  63  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  64  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  65  * SOFTWARE.
  66  */
  67
  68 /*
  69  * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
  70  *
  71  * Permission to use, copy, modify, and distribute this software for any
  72  * purpose with or without fee is hereby granted, provided that the above
  73  * copyright notice and this permission notice appear in all copies.
  74  *
  75  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
  76  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  77  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  78  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  79  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  80  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  81  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  82  * SOFTWARE.
  83  */
  84
  85 #include <sys/types.h>
  86 #include <sys/param.h>
  87 #include <netinet/in.h>
  88 #include <arpa/nameser.h>
  89 #include <netdb.h>
  90 #include <resolv/resolv-internal.h>
  91 #include <resolv/resolv_context.h>
  92 #include <string.h>
  93 #include <sys/time.h>
  94 #include <shlib-compat.h>
  95
  96 #include <hp-timing.h>
  97 #include <stdint.h>
  98 #if HP_TIMING_AVAIL
  99 # define RANDOM_BITS(Var) { uint64_t v64; HP_TIMING_NOW (v64); Var = v64; }
 100 #endif
 101
 102 int
 103 __res_context_mkquery (struct resolv_context *ctx, int op, const char *dname,
 104                        int class, int type, const unsigned char *data,
 105                        unsigned char *buf, int buflen)
 106 {
 107   HEADER *hp;
 108   unsigned char *cp;
 109   int n;
 110   unsigned char *dnptrs[20], **dpp, **lastdnptr;
 111
 112   if (class < 0 || class > 65535 || type < 0 || type > 65535)
 113     return -1;
 114
 115   /* Initialize header fields.  */
 116   if ((buf == NULL) || (buflen < HFIXEDSZ))
 117     return -1;
 118   memset (buf, 0, HFIXEDSZ);
 119   hp = (HEADER *) buf;
 120   /* We randomize the IDs every time.  The old code just incremented
 121      by one after the initial randomization which still predictable if
 122      the application does multiple requests.  */
 123   int randombits;
 124 #ifdef RANDOM_BITS
 125   RANDOM_BITS (randombits);
 126 #else
 127   struct timeval tv;
 128   __gettimeofday (&tv, NULL);
 129   randombits = (tv.tv_sec << 8) ^ tv.tv_usec;
 130 #endif
 131
 132   hp->id = randombits;
 133   hp->opcode = op;
 134   hp->rd = (ctx->resp->options & RES_RECURSE) != 0;
 135   hp->rcode = NOERROR;
 136   cp = buf + HFIXEDSZ;
 137   buflen -= HFIXEDSZ;
 138   dpp = dnptrs;
 139   *dpp++ = buf;
 140   *dpp++ = NULL;
 141   lastdnptr = dnptrs + sizeof dnptrs / sizeof dnptrs[0];
 142
 143   /* Perform opcode specific processing.  */
 144   switch (op)
 145     {
 146     case NS_NOTIFY_OP:
 147       if ((buflen -= QFIXEDSZ + (data == NULL ? 0 : RRFIXEDSZ)) < 0)
 148         return -1;
 149       goto compose;
 150
 151     case QUERY:
 152       if ((buflen -= QFIXEDSZ) < 0)
 153         return -1;
 154     compose:
 155       n = ns_name_compress (dname, cp, buflen,
 156                             (const unsigned char **) dnptrs,
 157                             (const unsigned char **) lastdnptr);
 158       if (n < 0)
 159         return -1;
 160       cp += n;
 161       buflen -= n;
 162       NS_PUT16 (type, cp);
 163       NS_PUT16 (class, cp);
 164       hp->qdcount = htons (1);
 165       if (op == QUERY || data == NULL)
 166         break;
 167
 168       /* Make an additional record for completion domain.  */
 169       n = ns_name_compress ((char *)data, cp, buflen,
 170                             (const unsigned char **) dnptrs,
 171                             (const unsigned char **) lastdnptr);
 172       if (__glibc_unlikely (n < 0))
 173         return -1;
 174       cp += n;
 175       buflen -= n;
 176       NS_PUT16 (T_NULL, cp);
 177       NS_PUT16 (class, cp);
 178       NS_PUT32 (0, cp);
 179       NS_PUT16 (0, cp);
 180       hp->arcount = htons (1);
 181       break;
 182
 183     default:
 184       return -1;
 185     }
 186   return cp - buf;
 187 }
 188
 189 /* Common part of res_nmkquery and res_mkquery.  */
 190 static int
 191 context_mkquery_common (struct resolv_context *ctx,
 192                         int op, const char *dname, int class, int type,
 193                         const unsigned char *data,
 194                         unsigned char *buf, int buflen)
 195 {
 196   if (ctx == NULL)
 197     return -1;
 198   int result = __res_context_mkquery
 199     (ctx, op, dname, class, type, data, buf, buflen);
 200   if (result >= 2)
 201     memcpy (&ctx->resp->id, buf, 2);
 202   __resolv_context_put (ctx);
 203   return result;
 204 }
 205
 206 /* Form all types of queries.  Returns the size of the result or -1 on
 207    error.
 208
 209    STATP points to an initialized resolver state.  OP is the opcode of
 210    the query.  DNAME is the domain.  CLASS and TYPE are the DNS query
 211    class and type.  DATA can be NULL; otherwise, it is a pointer to a
 212    domain name which is included in the generated packet (if op ==
 213    NS_NOTIFY_OP).  BUF must point to the out buffer of BUFLEN bytes.
 214
 215    DATALEN and NEWRR_IN are currently ignored.  */
 216 int
 217 res_nmkquery (res_state statp, int op, const char *dname,
 218               int class, int type,
 219               const unsigned char *data, int datalen,
 220               const unsigned char *newrr_in,
 221               unsigned char *buf, int buflen)
 222 {
 223   return context_mkquery_common
 224     (__resolv_context_get_override (statp),
 225      op, dname, class, type, data, buf, buflen);
 226 }
 227
 228 int
 229 res_mkquery (int op, const char *dname, int class, int type,
 230              const unsigned char *data, int datalen,
 231              const unsigned char *newrr_in,
 232              unsigned char *buf, int buflen)
 233 {
 234   return context_mkquery_common
 235     (__resolv_context_get_preinit (),
 236      op, dname, class, type, data, buf, buflen);
 237 }
 238
 239 /* Create an OPT resource record.  Return the length of the final
 240    packet, or -1 on error.
 241
 242    STATP must be an initialized resolver state.  N0 is the current
 243    number of bytes of the packet (already written to BUF by the
 244    aller).  BUF is the packet being constructed.  The array it
 245    pointers to must be BUFLEN bytes long.  ANSLEN is the advertised
 246    EDNS buffer size (to be included in the OPT resource record).  */
 247 int
 248 __res_nopt (struct resolv_context *ctx,
 249             int n0, unsigned char *buf, int buflen, int anslen)
 250 {
 251   uint16_t flags = 0;
 252   HEADER *hp = (HEADER *) buf;
 253   unsigned char *cp = buf + n0;
 254   unsigned char *ep = buf + buflen;
 255
 256   if ((ep - cp) < 1 + RRFIXEDSZ)
 257     return -1;
 258
 259   /* Add the root label.  */
 260   *cp++ = 0;
 261
 262   NS_PUT16 (T_OPT, cp);         /* Record type.  */
 263
 264   /* Lowering the advertised buffer size based on the actual
 265      answer buffer size is desirable because the server will
 266      minimize the reply to fit into the UDP packet (and A
 267      non-minimal response might not fit the buffer).
 268
 269      The RESOLV_EDNS_BUFFER_SIZE limit could still result in TCP
 270      fallback and a non-minimal response which has to be
 271      hard-truncated in the stub resolver, but this is price to
 272      pay for avoiding fragmentation.  (This issue does not
 273      affect the nss_dns functions because they use the stub
 274      resolver in such a way that it allocates a properly sized
 275      response buffer.)  */
 276   {
 277     uint16_t buffer_size;
 278     if (anslen < 512)
 279       buffer_size = 512;
 280     else if (anslen > RESOLV_EDNS_BUFFER_SIZE)
 281       buffer_size = RESOLV_EDNS_BUFFER_SIZE;
 282     else
 283       buffer_size = anslen;
 284     NS_PUT16 (buffer_size, cp);
 285   }
 286
 287   *cp++ = NOERROR;              /* Extended RCODE.  */
 288   *cp++ = 0;                    /* EDNS version.  */
 289
 290   if (ctx->resp->options & RES_USE_DNSSEC)
 291     flags |= NS_OPT_DNSSEC_OK;
 292
 293   NS_PUT16 (flags, cp);
 294   NS_PUT16 (0, cp);       /* RDATA length (no options are preent).  */
 295   hp->arcount = htons (ntohs (hp->arcount) + 1);
 296
 297   return cp - buf;
 298 }
 299
 300 #if SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_2)
 301 # undef res_mkquery
 302 weak_alias (__res_mkquery, res_mkquery);
 303 #endif