contrib/sendmail-8.13.4/sendmail/sm_resolve.c

   1 /*
   2  * Copyright (c) 2000-2004 Sendmail, Inc. and its suppliers.
   3  *      All rights reserved.
   4  *
   5  * By using this file, you agree to the terms and conditions set
   6  * forth in the LICENSE file which can be found at the top level of
   7  * the sendmail distribution.
   8  *
   9  */
  10
  11 /*
  12  * Copyright (c) 1995, 1996, 1997, 1998, 1999 Kungliga Tekniska Högskolan
  13  * (Royal Institute of Technology, Stockholm, Sweden).
  14  * All rights reserved.
  15  *
  16  * Redistribution and use in source and binary forms, with or without
  17  * modification, are permitted provided that the following conditions
  18  * are met:
  19  *
  20  * 1. Redistributions of source code must retain the above copyright
  21  *    notice, this list of conditions and the following disclaimer.
  22  *
  23  * 2. Redistributions in binary form must reproduce the above copyright
  24  *    notice, this list of conditions and the following disclaimer in the
  25  *    documentation and/or other materials provided with the distribution.
  26  *
  27  * 3. Neither the name of the Institute nor the names of its contributors
  28  *    may be used to endorse or promote products derived from this software
  29  *    without specific prior written permission.
  30  *
  31  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  32  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  33  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  34  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  35  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  39  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  40  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  41  * SUCH DAMAGE.
  42  */
  43
  44 #include <sendmail.h>
  45 #if DNSMAP
  46 # if NAMED_BIND
  47 #  include "sm_resolve.h"
  48
  49 SM_RCSID("$Id: sm_resolve.c,v 8.33 2004/08/04 21:17:57 ca Exp $")
  50
  51 static struct stot
  52 {
  53         const char      *st_name;
  54         int             st_type;
  55 } stot[] =
  56 {
  57 #  if NETINET
  58         {       "A",            T_A             },
  59 #  endif /* NETINET */
  60 #  if NETINET6
  61         {       "AAAA",         T_AAAA          },
  62 #  endif /* NETINET6 */
  63         {       "NS",           T_NS            },
  64         {       "CNAME",        T_CNAME         },
  65         {       "PTR",          T_PTR           },
  66         {       "MX",           T_MX            },
  67         {       "TXT",          T_TXT           },
  68         {       "AFSDB",        T_AFSDB         },
  69         {       "SRV",          T_SRV           },
  70         {       NULL,           0               }
  71 };
  72
  73 static DNS_REPLY_T *parse_dns_reply __P((unsigned char *, int));
  74
  75 /*
  76 **  DNS_STRING_TO_TYPE -- convert resource record name into type
  77 **
  78 **      Parameters:
  79 **              name -- name of resource record type
  80 **
  81 **      Returns:
  82 **              type if succeeded.
  83 **              -1 otherwise.
  84 */
  85
  86 int
  87 dns_string_to_type(name)
  88         const char *name;
  89 {
  90         struct stot *p = stot;
  91
  92         for (p = stot; p->st_name != NULL; p++)
  93                 if (sm_strcasecmp(name, p->st_name) == 0)
  94                         return p->st_type;
  95         return -1;
  96 }
  97
  98 /*
  99 **  DNS_TYPE_TO_STRING -- convert resource record type into name
 100 **
 101 **      Parameters:
 102 **              type -- resource record type
 103 **
 104 **      Returns:
 105 **              name if succeeded.
 106 **              NULL otherwise.
 107 */
 108
 109 const char *
 110 dns_type_to_string(type)
 111         int type;
 112 {
 113         struct stot *p = stot;
 114
 115         for (p = stot; p->st_name != NULL; p++)
 116                 if (type == p->st_type)
 117                         return p->st_name;
 118         return NULL;
 119 }
 120
 121 /*
 122 **  DNS_FREE_DATA -- free all components of a DNS_REPLY_T
 123 **
 124 **      Parameters:
 125 **              r -- pointer to DNS_REPLY_T
 126 **
 127 **      Returns:
 128 **              none.
 129 */
 130
 131 void
 132 dns_free_data(r)
 133         DNS_REPLY_T *r;
 134 {
 135         RESOURCE_RECORD_T *rr;
 136
 137         if (r->dns_r_q.dns_q_domain != NULL)
 138                 sm_free(r->dns_r_q.dns_q_domain);
 139         for (rr = r->dns_r_head; rr != NULL; )
 140         {
 141                 RESOURCE_RECORD_T *tmp = rr;
 142
 143                 if (rr->rr_domain != NULL)
 144                         sm_free(rr->rr_domain);
 145                 if (rr->rr_u.rr_data != NULL)
 146                         sm_free(rr->rr_u.rr_data);
 147                 rr = rr->rr_next;
 148                 sm_free(tmp);
 149         }
 150         sm_free(r);
 151 }
 152
 153 /*
 154 **  PARSE_DNS_REPLY -- parse DNS reply data.
 155 **
 156 **      Parameters:
 157 **              data -- pointer to dns data
 158 **              len -- len of data
 159 **
 160 **      Returns:
 161 **              pointer to DNS_REPLY_T if succeeded.
 162 **              NULL otherwise.
 163 */
 164
 165 static DNS_REPLY_T *
 166 parse_dns_reply(data, len)
 167         unsigned char *data;
 168         int len;
 169 {
 170         unsigned char *p;
 171         int status;
 172         size_t l;
 173         char host[MAXHOSTNAMELEN];
 174         DNS_REPLY_T *r;
 175         RESOURCE_RECORD_T **rr;
 176
 177         r = (DNS_REPLY_T *) sm_malloc(sizeof(*r));
 178         if (r == NULL)
 179                 return NULL;
 180         memset(r, 0, sizeof(*r));
 181
 182         p = data;
 183
 184         /* doesn't work on Crays? */
 185         memcpy(&r->dns_r_h, p, sizeof(r->dns_r_h));
 186         p += sizeof(r->dns_r_h);
 187         status = dn_expand(data, data + len, p, host, sizeof host);
 188         if (status < 0)
 189         {
 190                 dns_free_data(r);
 191                 return NULL;
 192         }
 193         r->dns_r_q.dns_q_domain = sm_strdup(host);
 194         if (r->dns_r_q.dns_q_domain == NULL)
 195         {
 196                 dns_free_data(r);
 197                 return NULL;
 198         }
 199         p += status;
 200         GETSHORT(r->dns_r_q.dns_q_type, p);
 201         GETSHORT(r->dns_r_q.dns_q_class, p);
 202         rr = &r->dns_r_head;
 203         while (p < data + len)
 204         {
 205                 int type, class, ttl, size, txtlen;
 206
 207                 status = dn_expand(data, data + len, p, host, sizeof host);
 208                 if (status < 0)
 209                 {
 210                         dns_free_data(r);
 211                         return NULL;
 212                 }
 213                 p += status;
 214                 GETSHORT(type, p);
 215                 GETSHORT(class, p);
 216                 GETLONG(ttl, p);
 217                 GETSHORT(size, p);
 218                 if (p + size > data + len)
 219                 {
 220                         /*
 221                         **  announced size of data exceeds length of
 222                         **  data paket: someone is cheating.
 223                         */
 224
 225                         if (LogLevel > 5)
 226                                 sm_syslog(LOG_WARNING, NOQID,
 227                                           "ERROR: DNS RDLENGTH=%d > data len=%d",
 228                                           size, len - (p - data));
 229                         dns_free_data(r);
 230                         return NULL;
 231                 }
 232                 *rr = (RESOURCE_RECORD_T *) sm_malloc(sizeof(**rr));
 233                 if (*rr == NULL)
 234                 {
 235                         dns_free_data(r);
 236                         return NULL;
 237                 }
 238                 memset(*rr, 0, sizeof(**rr));
 239                 (*rr)->rr_domain = sm_strdup(host);
 240                 if ((*rr)->rr_domain == NULL)
 241                 {
 242                         dns_free_data(r);
 243                         return NULL;
 244                 }
 245                 (*rr)->rr_type = type;
 246                 (*rr)->rr_class = class;
 247                 (*rr)->rr_ttl = ttl;
 248                 (*rr)->rr_size = size;
 249                 switch (type)
 250                 {
 251                   case T_NS:
 252                   case T_CNAME:
 253                   case T_PTR:
 254                         status = dn_expand(data, data + len, p, host,
 255                                            sizeof host);
 256                         if (status < 0)
 257                         {
 258                                 dns_free_data(r);
 259                                 return NULL;
 260                         }
 261                         (*rr)->rr_u.rr_txt = sm_strdup(host);
 262                         if ((*rr)->rr_u.rr_txt == NULL)
 263                         {
 264                                 dns_free_data(r);
 265                                 return NULL;
 266                         }
 267                         break;
 268
 269                   case T_MX:
 270                   case T_AFSDB:
 271                         status = dn_expand(data, data + len, p + 2, host,
 272                                            sizeof host);
 273                         if (status < 0)
 274                         {
 275                                 dns_free_data(r);
 276                                 return NULL;
 277                         }
 278                         l = strlen(host) + 1;
 279                         (*rr)->rr_u.rr_mx = (MX_RECORD_T *)
 280                                 sm_malloc(sizeof(*((*rr)->rr_u.rr_mx)) + l);
 281                         if ((*rr)->rr_u.rr_mx == NULL)
 282                         {
 283                                 dns_free_data(r);
 284                                 return NULL;
 285                         }
 286                         (*rr)->rr_u.rr_mx->mx_r_preference = (p[0] << 8) | p[1];
 287                         (void) sm_strlcpy((*rr)->rr_u.rr_mx->mx_r_domain,
 288                                           host, l);
 289                         break;
 290
 291                   case T_SRV:
 292                         status = dn_expand(data, data + len, p + 6, host,
 293                                            sizeof host);
 294                         if (status < 0)
 295                         {
 296                                 dns_free_data(r);
 297                                 return NULL;
 298                         }
 299                         l = strlen(host) + 1;
 300                         (*rr)->rr_u.rr_srv = (SRV_RECORDT_T*)
 301                                 sm_malloc(sizeof(*((*rr)->rr_u.rr_srv)) + l);
 302                         if ((*rr)->rr_u.rr_srv == NULL)
 303                         {
 304                                 dns_free_data(r);
 305                                 return NULL;
 306                         }
 307                         (*rr)->rr_u.rr_srv->srv_r_priority = (p[0] << 8) | p[1];
 308                         (*rr)->rr_u.rr_srv->srv_r_weight = (p[2] << 8) | p[3];
 309                         (*rr)->rr_u.rr_srv->srv_r_port = (p[4] << 8) | p[5];
 310                         (void) sm_strlcpy((*rr)->rr_u.rr_srv->srv_r_target,
 311                                           host, l);
 312                         break;
 313
 314                   case T_TXT:
 315
 316                         /*
 317                         **  The TXT record contains the length as
 318                         **  leading byte, hence the value is restricted
 319                         **  to 255, which is less than the maximum value
 320                         **  of RDLENGTH (size). Nevertheless, txtlen
 321                         **  must be less than size because the latter
 322                         **  specifies the length of the entire TXT
 323                         **  record.
 324                         */
 325
 326                         txtlen = *p;
 327                         if (txtlen >= size)
 328                         {
 329                                 if (LogLevel > 5)
 330                                         sm_syslog(LOG_WARNING, NOQID,
 331                                                   "ERROR: DNS TXT record size=%d <= text len=%d",
 332                                                   size, txtlen);
 333                                 dns_free_data(r);
 334                                 return NULL;
 335                         }
 336                         (*rr)->rr_u.rr_txt = (char *) sm_malloc(txtlen + 1);
 337                         if ((*rr)->rr_u.rr_txt == NULL)
 338                         {
 339                                 dns_free_data(r);
 340                                 return NULL;
 341                         }
 342                         (void) sm_strlcpy((*rr)->rr_u.rr_txt, (char*) p + 1,
 343                                           txtlen + 1);
 344                         break;
 345
 346                   default:
 347                         (*rr)->rr_u.rr_data = (unsigned char*) sm_malloc(size);
 348                         if ((*rr)->rr_u.rr_data == NULL)
 349                         {
 350                                 dns_free_data(r);
 351                                 return NULL;
 352                         }
 353                         (void) memcpy((*rr)->rr_u.rr_data, p, size);
 354                         break;
 355                 }
 356                 p += size;
 357                 rr = &(*rr)->rr_next;
 358         }
 359         *rr = NULL;
 360         return r;
 361 }
 362
 363 /*
 364 **  DNS_LOOKUP_INT -- perform dns map lookup (internal helper routine)
 365 **
 366 **      Parameters:
 367 **              domain -- name to lookup
 368 **              rr_class -- resource record class
 369 **              rr_type -- resource record type
 370 **              retrans -- retransmission timeout
 371 **              retry -- number of retries
 372 **
 373 **      Returns:
 374 **              result of lookup if succeeded.
 375 **              NULL otherwise.
 376 */
 377
 378 DNS_REPLY_T *
 379 dns_lookup_int(domain, rr_class, rr_type, retrans, retry)
 380         const char *domain;
 381         int rr_class;
 382         int rr_type;
 383         time_t retrans;
 384         int retry;
 385 {
 386         int len;
 387         unsigned long old_options = 0;
 388         time_t save_retrans = 0;
 389         int save_retry = 0;
 390         DNS_REPLY_T *r = NULL;
 391         unsigned char reply[1024];
 392
 393         if (tTd(8, 16))
 394         {
 395                 old_options = _res.options;
 396                 _res.options |= RES_DEBUG;
 397                 sm_dprintf("dns_lookup(%s, %d, %s)\n", domain,
 398                            rr_class, dns_type_to_string(rr_type));
 399         }
 400         if (retrans > 0)
 401         {
 402                 save_retrans = _res.retrans;
 403                 _res.retrans = retrans;
 404         }
 405         if (retry > 0)
 406         {
 407                 save_retry = _res.retry;
 408                 _res.retry = retry;
 409         }
 410         errno = 0;
 411         SM_SET_H_ERRNO(0);
 412         len = res_search(domain, rr_class, rr_type, reply, sizeof reply);
 413         if (tTd(8, 16))
 414         {
 415                 _res.options = old_options;
 416                 sm_dprintf("dns_lookup(%s, %d, %s) --> %d\n",
 417                            domain, rr_class, dns_type_to_string(rr_type), len);
 418         }
 419         if (len >= 0)
 420                 r = parse_dns_reply(reply, len);
 421         if (retrans > 0)
 422                 _res.retrans = save_retrans;
 423         if (retry > 0)
 424                 _res.retry = save_retry;
 425         return r;
 426 }
 427
 428 #  if 0
 429 DNS_REPLY_T *
 430 dns_lookup(domain, type_name, retrans, retry)
 431         const char *domain;
 432         const char *type_name;
 433         time_t retrans;
 434         int retry;
 435 {
 436         int type;
 437
 438         type = dns_string_to_type(type_name);
 439         if (type == -1)
 440         {
 441                 if (tTd(8, 16))
 442                         sm_dprintf("dns_lookup: unknown resource type: `%s'\n",
 443                                 type_name);
 444                 return NULL;
 445         }
 446         return dns_lookup_int(domain, C_IN, type, retrans, retry);
 447 }
 448 #  endif /* 0 */
 449 # endif /* NAMED_BIND */
 450 #endif /* DNSMAP */