contrib/sendmail-8.14/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 8.36 2008/02/11 23:04:16 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         unsigned short ans_cnt, ui;
 172         int status;
 173         size_t l;
 174         char host[MAXHOSTNAMELEN];
 175         DNS_REPLY_T *r;
 176         RESOURCE_RECORD_T **rr;
 177
 178         r = (DNS_REPLY_T *) sm_malloc(sizeof(*r));
 179         if (r == NULL)
 180                 return NULL;
 181         memset(r, 0, sizeof(*r));
 182
 183         p = data;
 184
 185         /* doesn't work on Crays? */
 186         memcpy(&r->dns_r_h, p, sizeof(r->dns_r_h));
 187         p += sizeof(r->dns_r_h);
 188         status = dn_expand(data, data + len, p, host, sizeof(host));
 189         if (status < 0)
 190         {
 191                 dns_free_data(r);
 192                 return NULL;
 193         }
 194         r->dns_r_q.dns_q_domain = sm_strdup(host);
 195         if (r->dns_r_q.dns_q_domain == NULL)
 196         {
 197                 dns_free_data(r);
 198                 return NULL;
 199         }
 200
 201         ans_cnt = ntohs((unsigned short) r->dns_r_h.ancount);
 202
 203         p += status;
 204         GETSHORT(r->dns_r_q.dns_q_type, p);
 205         GETSHORT(r->dns_r_q.dns_q_class, p);
 206         rr = &r->dns_r_head;
 207         ui = 0;
 208         while (p < data + len && ui < ans_cnt)
 209         {
 210                 int type, class, ttl, size, txtlen;
 211
 212                 status = dn_expand(data, data + len, p, host, sizeof(host));
 213                 if (status < 0)
 214                 {
 215                         dns_free_data(r);
 216                         return NULL;
 217                 }
 218                 ++ui;
 219                 p += status;
 220                 GETSHORT(type, p);
 221                 GETSHORT(class, p);
 222                 GETLONG(ttl, p);
 223                 GETSHORT(size, p);
 224                 if (p + size > data + len)
 225                 {
 226                         /*
 227                         **  announced size of data exceeds length of
 228                         **  data paket: someone is cheating.
 229                         */
 230
 231                         if (LogLevel > 5)
 232                                 sm_syslog(LOG_WARNING, NOQID,
 233                                           "ERROR: DNS RDLENGTH=%d > data len=%d",
 234                                           size, len - (p - data));
 235                         dns_free_data(r);
 236                         return NULL;
 237                 }
 238                 *rr = (RESOURCE_RECORD_T *) sm_malloc(sizeof(**rr));
 239                 if (*rr == NULL)
 240                 {
 241                         dns_free_data(r);
 242                         return NULL;
 243                 }
 244                 memset(*rr, 0, sizeof(**rr));
 245                 (*rr)->rr_domain = sm_strdup(host);
 246                 if ((*rr)->rr_domain == NULL)
 247                 {
 248                         dns_free_data(r);
 249                         return NULL;
 250                 }
 251                 (*rr)->rr_type = type;
 252                 (*rr)->rr_class = class;
 253                 (*rr)->rr_ttl = ttl;
 254                 (*rr)->rr_size = size;
 255                 switch (type)
 256                 {
 257                   case T_NS:
 258                   case T_CNAME:
 259                   case T_PTR:
 260                         status = dn_expand(data, data + len, p, host,
 261                                            sizeof(host));
 262                         if (status < 0)
 263                         {
 264                                 dns_free_data(r);
 265                                 return NULL;
 266                         }
 267                         (*rr)->rr_u.rr_txt = sm_strdup(host);
 268                         if ((*rr)->rr_u.rr_txt == NULL)
 269                         {
 270                                 dns_free_data(r);
 271                                 return NULL;
 272                         }
 273                         break;
 274
 275                   case T_MX:
 276                   case T_AFSDB:
 277                         status = dn_expand(data, data + len, p + 2, host,
 278                                            sizeof(host));
 279                         if (status < 0)
 280                         {
 281                                 dns_free_data(r);
 282                                 return NULL;
 283                         }
 284                         l = strlen(host) + 1;
 285                         (*rr)->rr_u.rr_mx = (MX_RECORD_T *)
 286                                 sm_malloc(sizeof(*((*rr)->rr_u.rr_mx)) + l);
 287                         if ((*rr)->rr_u.rr_mx == NULL)
 288                         {
 289                                 dns_free_data(r);
 290                                 return NULL;
 291                         }
 292                         (*rr)->rr_u.rr_mx->mx_r_preference = (p[0] << 8) | p[1];
 293                         (void) sm_strlcpy((*rr)->rr_u.rr_mx->mx_r_domain,
 294                                           host, l);
 295                         break;
 296
 297                   case T_SRV:
 298                         status = dn_expand(data, data + len, p + 6, host,
 299                                            sizeof(host));
 300                         if (status < 0)
 301                         {
 302                                 dns_free_data(r);
 303                                 return NULL;
 304                         }
 305                         l = strlen(host) + 1;
 306                         (*rr)->rr_u.rr_srv = (SRV_RECORDT_T*)
 307                                 sm_malloc(sizeof(*((*rr)->rr_u.rr_srv)) + l);
 308                         if ((*rr)->rr_u.rr_srv == NULL)
 309                         {
 310                                 dns_free_data(r);
 311                                 return NULL;
 312                         }
 313                         (*rr)->rr_u.rr_srv->srv_r_priority = (p[0] << 8) | p[1];
 314                         (*rr)->rr_u.rr_srv->srv_r_weight = (p[2] << 8) | p[3];
 315                         (*rr)->rr_u.rr_srv->srv_r_port = (p[4] << 8) | p[5];
 316                         (void) sm_strlcpy((*rr)->rr_u.rr_srv->srv_r_target,
 317                                           host, l);
 318                         break;
 319
 320                   case T_TXT:
 321
 322                         /*
 323                         **  The TXT record contains the length as
 324                         **  leading byte, hence the value is restricted
 325                         **  to 255, which is less than the maximum value
 326                         **  of RDLENGTH (size). Nevertheless, txtlen
 327                         **  must be less than size because the latter
 328                         **  specifies the length of the entire TXT
 329                         **  record.
 330                         */
 331
 332                         txtlen = *p;
 333                         if (txtlen >= size)
 334                         {
 335                                 if (LogLevel > 5)
 336                                         sm_syslog(LOG_WARNING, NOQID,
 337                                                   "ERROR: DNS TXT record size=%d <= text len=%d",
 338                                                   size, txtlen);
 339                                 dns_free_data(r);
 340                                 return NULL;
 341                         }
 342                         (*rr)->rr_u.rr_txt = (char *) sm_malloc(txtlen + 1);
 343                         if ((*rr)->rr_u.rr_txt == NULL)
 344                         {
 345                                 dns_free_data(r);
 346                                 return NULL;
 347                         }
 348                         (void) sm_strlcpy((*rr)->rr_u.rr_txt, (char*) p + 1,
 349                                           txtlen + 1);
 350                         break;
 351
 352                   default:
 353                         (*rr)->rr_u.rr_data = (unsigned char*) sm_malloc(size);
 354                         if ((*rr)->rr_u.rr_data == NULL)
 355                         {
 356                                 dns_free_data(r);
 357                                 return NULL;
 358                         }
 359                         (void) memcpy((*rr)->rr_u.rr_data, p, size);
 360                         break;
 361                 }
 362                 p += size;
 363                 rr = &(*rr)->rr_next;
 364         }
 365         *rr = NULL;
 366         return r;
 367 }
 368
 369 /*
 370 **  DNS_LOOKUP_INT -- perform dns map lookup (internal helper routine)
 371 **
 372 **      Parameters:
 373 **              domain -- name to lookup
 374 **              rr_class -- resource record class
 375 **              rr_type -- resource record type
 376 **              retrans -- retransmission timeout
 377 **              retry -- number of retries
 378 **
 379 **      Returns:
 380 **              result of lookup if succeeded.
 381 **              NULL otherwise.
 382 */
 383
 384 DNS_REPLY_T *
 385 dns_lookup_int(domain, rr_class, rr_type, retrans, retry)
 386         const char *domain;
 387         int rr_class;
 388         int rr_type;
 389         time_t retrans;
 390         int retry;
 391 {
 392         int len;
 393         unsigned long old_options = 0;
 394         time_t save_retrans = 0;
 395         int save_retry = 0;
 396         DNS_REPLY_T *r = NULL;
 397         unsigned char reply[1024];
 398
 399         if (tTd(8, 16))
 400         {
 401                 old_options = _res.options;
 402                 _res.options |= RES_DEBUG;
 403                 sm_dprintf("dns_lookup(%s, %d, %s)\n", domain,
 404                            rr_class, dns_type_to_string(rr_type));
 405         }
 406         if (retrans > 0)
 407         {
 408                 save_retrans = _res.retrans;
 409                 _res.retrans = retrans;
 410         }
 411         if (retry > 0)
 412         {
 413                 save_retry = _res.retry;
 414                 _res.retry = retry;
 415         }
 416         errno = 0;
 417         SM_SET_H_ERRNO(0);
 418         len = res_search(domain, rr_class, rr_type, reply, sizeof(reply));
 419         if (tTd(8, 16))
 420         {
 421                 _res.options = old_options;
 422                 sm_dprintf("dns_lookup(%s, %d, %s) --> %d\n",
 423                            domain, rr_class, dns_type_to_string(rr_type), len);
 424         }
 425         if (len >= 0)
 426                 r = parse_dns_reply(reply, len);
 427         if (retrans > 0)
 428                 _res.retrans = save_retrans;
 429         if (retry > 0)
 430                 _res.retry = save_retry;
 431         return r;
 432 }
 433
 434 #  if 0
 435 DNS_REPLY_T *
 436 dns_lookup(domain, type_name, retrans, retry)
 437         const char *domain;
 438         const char *type_name;
 439         time_t retrans;
 440         int retry;
 441 {
 442         int type;
 443
 444         type = dns_string_to_type(type_name);
 445         if (type == -1)
 446         {
 447                 if (tTd(8, 16))
 448                         sm_dprintf("dns_lookup: unknown resource type: `%s'\n",
 449                                 type_name);
 450                 return NULL;
 451         }
 452         return dns_lookup_int(domain, C_IN, type, retrans, retry);
 453 }
 454 #  endif /* 0 */
 455 # endif /* NAMED_BIND */
 456 #endif /* DNSMAP */