libcli/dns/dns_hosts_file.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    read a file containing DNS names, types and IP addresses
   5
   6    Copyright (C) Andrew Tridgell 1994-1998
   7    Copyright (C) Jeremy Allison 2007
   8    Copyright (C) Andrew Bartlett 2009-2011
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  22 */
  23
  24 /* The purpose of this file is to read the file generated by the samba_dnsupdate script */
  25
  26 #include "includes.h"
  27 #include "lib/util/xfile.h"
  28 #include "lib/util/util_net.h"
  29 #include "system/filesys.h"
  30 #include "system/network.h"
  31 #include "libcli/nbt/libnbt.h"
  32 #include "libcli/dns/dns.h"
  33
  34 #ifdef strcasecmp
  35 #undef strcasecmp
  36 #endif
  37
  38 /********************************************************
  39  Start parsing the dns_hosts_file file.
  40 *********************************************************/
  41
  42 static XFILE *startdns_hosts_file(const char *fname)
  43 {
  44         XFILE *fp = x_fopen(fname,O_RDONLY, 0);
  45         if (!fp) {
  46                 DEBUG(4,("startdns_hosts_file: Can't open dns_hosts_file file %s. "
  47                         "Error was %s\n",
  48                         fname, strerror(errno)));
  49                 return NULL;
  50         }
  51         return fp;
  52 }
  53
  54 /********************************************************
  55  Parse the next line in the dns_hosts_file file.
  56 *********************************************************/
  57
  58 static bool getdns_hosts_fileent(TALLOC_CTX *ctx, XFILE *fp, char **pp_name, char **pp_name_type,
  59                           char **pp_next_name,
  60                           struct sockaddr_storage *pss, uint32_t *p_port)
  61 {
  62         char line[1024];
  63
  64         *pp_name = NULL;
  65         *pp_name_type = NULL;
  66         *pp_next_name = NULL;
  67         *p_port = 0;
  68
  69         while(!x_feof(fp) && !x_ferror(fp)) {
  70                 char *name_type = NULL;
  71                 char *name = NULL;
  72                 char *next_name = NULL;
  73                 char *ip = NULL;
  74                 char *port = NULL;
  75
  76                 const char *ptr;
  77                 int count = 0;
  78
  79                 if (!fgets_slash(line,sizeof(line),fp)) {
  80                         continue;
  81                 }
  82
  83                 if (*line == '#') {
  84                         continue;
  85                 }
  86
  87                 ptr = line;
  88
  89                 if (next_token_talloc(ctx, &ptr, &name_type, NULL))
  90                         ++count;
  91                 if (next_token_talloc(ctx, &ptr, &name, NULL))
  92                         ++count;
  93                 if (name_type && strcasecmp(name_type, "A") == 0) {
  94                         if (next_token_talloc(ctx, &ptr, &ip, NULL))
  95                                 ++count;
  96                 } else if (name_type && strcasecmp(name_type, "SRV") == 0) {
  97                         if (next_token_talloc(ctx, &ptr, &next_name, NULL))
  98                                 ++count;
  99                         if (next_token_talloc(ctx, &ptr, &port, NULL))
 100                                 ++count;
 101                 } else if (name_type && strcasecmp(name_type, "CNAME") == 0) {
 102                         if (next_token_talloc(ctx, &ptr, &next_name, NULL))
 103                                 ++count;
 104                 }
 105                 if (count <= 0)
 106                         continue;
 107
 108                 if (strcasecmp(name_type, "A") == 0) {
 109                         if (count != 3) {
 110                                 DEBUG(0,("getdns_hosts_fileent: Ill formed hosts A record [%s]\n",
 111                                          line));
 112                                 continue;
 113                         }
 114                         DEBUG(4, ("getdns_hosts_fileent: host entry: %s %s %s\n",
 115                                   name_type, name, ip));
 116                         if (!interpret_string_addr(pss, ip, AI_NUMERICHOST)) {
 117                                 DEBUG(0,("getdns_hosts_fileent: invalid address "
 118                                          "%s.\n", ip));
 119                         }
 120
 121                 } else if (strcasecmp(name_type, "SRV") == 0) {
 122                         if (count != 4) {
 123                                 DEBUG(0,("getdns_hosts_fileent: Ill formed hosts SRV record [%s]\n",
 124                                          line));
 125                                 continue;
 126                         }
 127                         *p_port = strtoul(port, NULL, 10);
 128                         if (*p_port == UINT32_MAX) {
 129                                 DEBUG(0, ("getdns_hosts_fileent: Ill formed hosts SRV record [%s] (invalid port: %s)\n",
 130                                           line, port));
 131                                 continue;
 132                         }
 133                         DEBUG(4, ("getdns_hosts_fileent: host entry: %s %s %s %u\n",
 134                                   name_type, name, next_name, (unsigned int)*p_port));
 135                         *pp_next_name = talloc_strdup(ctx, next_name);
 136                         if (!*pp_next_name) {
 137                                 return false;
 138                         }
 139                 } else if (strcasecmp(name_type, "CNAME") == 0) {
 140                         if (count != 3) {
 141                                 DEBUG(0,("getdns_hosts_fileent: Ill formed hosts CNAME record [%s]\n",
 142                                          line));
 143                                 continue;
 144                         }
 145                         DEBUG(4, ("getdns_hosts_fileent: host entry: %s %s %s\n",
 146                                   name_type, name, next_name));
 147                         *pp_next_name = talloc_strdup(ctx, next_name);
 148                         if (!*pp_next_name) {
 149                                 return false;
 150                         }
 151                 } else {
 152                         DEBUG(0,("getdns_hosts_fileent: unknown type %s\n", name_type));
 153                         continue;
 154                 }
 155
 156                 *pp_name = talloc_strdup(ctx, name);
 157                 if (!*pp_name) {
 158                         return false;
 159                 }
 160
 161                 *pp_name_type = talloc_strdup(ctx, name_type);
 162                 if (!*pp_name_type) {
 163                         return false;
 164                 }
 165                 return true;
 166         }
 167
 168         return false;
 169 }
 170
 171 /********************************************************
 172  Finish parsing the dns_hosts_file file.
 173 *********************************************************/
 174
 175 static void enddns_hosts_file(XFILE *fp)
 176 {
 177         x_fclose(fp);
 178 }
 179
 180 /********************************************************
 181  Resolve via "dns_hosts" method.
 182 *********************************************************/
 183
 184 static NTSTATUS resolve_dns_hosts_file_as_dns_rr_recurse(const char *dns_hosts_file,
 185                                                          const char *name, bool srv_lookup,
 186                                                          int level, uint32_t port,
 187                                                          TALLOC_CTX *mem_ctx,
 188                                                          struct dns_rr_srv **return_rr,
 189                                                          int *return_count)
 190 {
 191         /*
 192          * "dns_hosts" means parse the local dns_hosts file.
 193          */
 194
 195         XFILE *fp;
 196         char *host_name = NULL;
 197         char *name_type = NULL;
 198         char *next_name = NULL;
 199         struct sockaddr_storage return_ss;
 200         uint32_t srv_port;
 201         NTSTATUS status = NT_STATUS_OBJECT_NAME_NOT_FOUND;
 202         TALLOC_CTX *ctx = NULL;
 203         TALLOC_CTX *ip_list_ctx = NULL;
 204         struct dns_rr_srv *rr = NULL;
 205
 206         *return_rr = NULL;
 207
 208         /* Don't recurse forever, even on our own flat files */
 209         if (level > 11) {
 210                 DEBUG(0, ("resolve_dns_hosts_file recursion limit reached looking up %s!\n", name));
 211                 return status;
 212         }
 213
 214         *return_count = 0;
 215
 216         DEBUG(3,("resolve_dns_hosts: (%d) "
 217                  "Attempting %s dns_hosts lookup for name %s\n",
 218                  level, srv_lookup ? "SRV" : "A", name));
 219
 220         fp = startdns_hosts_file(dns_hosts_file);
 221
 222         if ( fp == NULL )
 223                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 224
 225         ip_list_ctx = talloc_new(mem_ctx);
 226         if (!ip_list_ctx) {
 227                 enddns_hosts_file(fp);
 228                 return NT_STATUS_NO_MEMORY;
 229         }
 230
 231         ctx = talloc_new(ip_list_ctx);
 232         if (!ctx) {
 233                 talloc_free(ip_list_ctx);
 234                 enddns_hosts_file(fp);
 235                 return NT_STATUS_NO_MEMORY;
 236         }
 237
 238         while (getdns_hosts_fileent(ctx, fp, &host_name, &name_type, &next_name, &return_ss, &srv_port)) {
 239                 if (!strequal(name, host_name)) {
 240                         /* continue at the bottom of the loop */
 241                 } else if (srv_lookup) {
 242                         if (strcasecmp(name_type, "SRV") == 0) {
 243                                 NTSTATUS status_recurse;
 244                                 struct dns_rr_srv *tmp_rr;
 245                                 int tmp_count = 0;
 246                                 /* we only accept one host name per SRV entry */
 247                                 status_recurse
 248                                         = resolve_dns_hosts_file_as_dns_rr_recurse(dns_hosts_file, next_name,
 249                                                                                      false,
 250                                                                                      level + 1, srv_port,
 251                                                                                      ip_list_ctx, &tmp_rr,
 252                                                                                      &tmp_count);
 253                                 if (NT_STATUS_EQUAL(status_recurse, NT_STATUS_OBJECT_NAME_NOT_FOUND)) {
 254                                         /* Don't fail on a dangling SRV record */
 255                                 } else if (!NT_STATUS_IS_OK(status_recurse)) {
 256                                         enddns_hosts_file(fp);
 257                                         talloc_free(ip_list_ctx);
 258                                         return status_recurse;
 259                                 } else if (tmp_count != 1) {
 260                                         status = NT_STATUS_OBJECT_NAME_NOT_FOUND;
 261                                 } else {
 262                                         status = status_recurse;
 263                                         rr = talloc_realloc(ip_list_ctx, rr, struct dns_rr_srv, (*return_count) + 1);
 264                                         if (!rr) {
 265                                                 enddns_hosts_file(fp);
 266                                                 return NT_STATUS_NO_MEMORY;
 267                                         }
 268                                         talloc_steal(rr, tmp_rr);
 269                                         rr[*return_count] = *tmp_rr;
 270                                         *return_count = (*return_count) + 1;
 271                                 }
 272                         }
 273                 } else if (strcasecmp(name_type, "CNAME") == 0) {
 274                         /* we only accept one host name per CNAME */
 275                         enddns_hosts_file(fp);
 276                         status = resolve_dns_hosts_file_as_dns_rr_recurse(dns_hosts_file, next_name, false,
 277                                                                           level + 1, port,
 278                                                                           mem_ctx, return_rr, return_count);
 279                         talloc_free(ip_list_ctx);
 280                         return status;
 281                 } else if (strcasecmp(name_type, "A") == 0) {
 282                         if (*return_count == 0) {
 283                                 /* We are happy to keep looking for other possible A record matches */
 284                                 rr = talloc_zero(ip_list_ctx,
 285                                                   struct dns_rr_srv);
 286
 287                                 if (rr == NULL) {
 288                                         TALLOC_FREE(ctx);
 289                                         enddns_hosts_file(fp);
 290                                         DEBUG(3,("resolve_dns_hosts: talloc_realloc fail !\n"));
 291                                         return NT_STATUS_NO_MEMORY;
 292                                 }
 293
 294                                 rr->hostname = talloc_strdup(rr, host_name);
 295
 296                                 if (rr->hostname == NULL) {
 297                                         TALLOC_FREE(ctx);
 298                                         enddns_hosts_file(fp);
 299                                         DEBUG(3,("resolve_dns_hosts: talloc_realloc fail !\n"));
 300                                         return NT_STATUS_NO_MEMORY;
 301                                 }
 302                                 rr->port = port;
 303
 304                                 *return_count = 1;
 305                         }
 306
 307                         /* Set the specified port (possibly from a SRV lookup) into the structure we return */
 308                         set_sockaddr_port((struct sockaddr *)&return_ss, port);
 309
 310                         /* We are happy to keep looking for other possible A record matches */
 311                         rr->ss_s = talloc_realloc(rr, rr->ss_s,
 312                                                   struct sockaddr_storage,
 313                                                   rr->num_ips + 1);
 314
 315                         if (rr->ss_s == NULL) {
 316                                 TALLOC_FREE(ctx);
 317                                 enddns_hosts_file(fp);
 318                                 DEBUG(3,("resolve_dns_hosts: talloc_realloc fail !\n"));
 319                                 return NT_STATUS_NO_MEMORY;
 320                         }
 321
 322                         rr->ss_s[rr->num_ips] = return_ss;
 323                         rr->num_ips += 1;
 324
 325                         /* we found something */
 326                         status = NT_STATUS_OK;
 327                 }
 328
 329                 TALLOC_FREE(ctx);
 330                 ctx = talloc_new(mem_ctx);
 331                 if (!ctx) {
 332                         enddns_hosts_file(fp);
 333                         return NT_STATUS_NO_MEMORY;
 334                 }
 335         }
 336
 337         *return_rr = talloc_steal(mem_ctx, rr);
 338         TALLOC_FREE(ip_list_ctx);
 339         enddns_hosts_file(fp);
 340         return status;
 341 }
 342
 343 /********************************************************
 344  Resolve via "dns_hosts_file" method, returning a list of sockaddr_storage values
 345 *********************************************************/
 346
 347 NTSTATUS resolve_dns_hosts_file_as_sockaddr(const char *dns_hosts_file,
 348                                             const char *name, bool srv_lookup,
 349                                             TALLOC_CTX *mem_ctx,
 350                                             struct sockaddr_storage **return_iplist,
 351                                             int *return_count)
 352 {
 353         NTSTATUS status;
 354         struct dns_rr_srv *dns_rr = NULL;
 355         int i, j, rr_count = 0;
 356
 357         *return_iplist = NULL;
 358         *return_count = 0;
 359
 360         status = resolve_dns_hosts_file_as_dns_rr_recurse(dns_hosts_file, name, srv_lookup,
 361                                                           0, 0,
 362                                                           mem_ctx, &dns_rr, &rr_count);
 363         if (!NT_STATUS_IS_OK(status)) {
 364                 DEBUG(3,("resolve_dns_hosts (sockaddr): "
 365                          "failed to obtain %s result records for for name %s: %s\n",
 366                          srv_lookup ? "SRV" : "A", name, nt_errstr(status)));
 367                 return status;
 368         }
 369
 370         for (i=0; i < rr_count; i++) {
 371                 *return_iplist = talloc_realloc(mem_ctx, *return_iplist, struct sockaddr_storage, *return_count + dns_rr[i].num_ips);
 372                 if (!*return_iplist) {
 373                         return NT_STATUS_NO_MEMORY;
 374                 }
 375                 for (j=0; j < dns_rr[i].num_ips; j++) {
 376                         (*return_iplist)[*return_count] = dns_rr[i].ss_s[j];
 377                         *return_count = *return_count + 1;
 378                 }
 379         }
 380         DEBUG(3,("resolve_dns_hosts (sockaddr): "
 381                 "Found %d results for for name %s\n",
 382                  *return_count, name));
 383
 384         return NT_STATUS_OK;
 385 }
 386
 387 /********************************************************
 388  Resolve via "dns_hosts_file" method, returning struct dns_rr_srv
 389 *********************************************************/
 390
 391 NTSTATUS resolve_dns_hosts_file_as_dns_rr(const char *dns_hosts_file,
 392                                             const char *name, bool srv_lookup,
 393                                             TALLOC_CTX *mem_ctx,
 394                                             struct dns_rr_srv **return_rr,
 395                                             int *return_count)
 396 {
 397         NTSTATUS status;
 398         *return_rr = NULL;
 399         *return_count = 0;
 400
 401         status = resolve_dns_hosts_file_as_dns_rr_recurse(dns_hosts_file, name, srv_lookup,
 402                                                           0, 0,
 403                                                           mem_ctx, return_rr, return_count);
 404
 405         if (NT_STATUS_IS_OK(status)) {
 406                 DEBUG(3,("resolve_dns_hosts (dns_rr): "
 407                          "Found %d %s result records for for name %s\n",
 408                          *return_count, srv_lookup ? "SRV" : "A", name));
 409         } else {
 410                 DEBUG(3,("resolve_dns_hosts (dns_rr): "
 411                          "failed to obtain %s result records for for name %s: %s\n",
 412                          srv_lookup ? "SRV" : "A", name, nt_errstr(status)));
 413         }
 414         return status;
 415 }