libcli/nbt/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.
   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
  32 /********************************************************
  33  Start parsing the dns_hosts_file file.
  34 *********************************************************/
  35
  36 static XFILE *startdns_hosts_file(const char *fname)
  37 {
  38         XFILE *fp = x_fopen(fname,O_RDONLY, 0);
  39         if (!fp) {
  40                 DEBUG(4,("startdns_hosts_file: Can't open dns_hosts_file file %s. "
  41                         "Error was %s\n",
  42                         fname, strerror(errno)));
  43                 return NULL;
  44         }
  45         return fp;
  46 }
  47
  48 /********************************************************
  49  Parse the next line in the dns_hosts_file file.
  50 *********************************************************/
  51
  52 static bool getdns_hosts_fileent(TALLOC_CTX *ctx, XFILE *fp, char **pp_name, char **pp_name_type,
  53                           char **pp_next_name,
  54                           struct sockaddr_storage *pss, uint32_t *p_port)
  55 {
  56         char line[1024];
  57
  58         *pp_name = NULL;
  59         *pp_name_type = NULL;
  60         *pp_next_name = NULL;
  61         *p_port = 0;
  62
  63         while(!x_feof(fp) && !x_ferror(fp)) {
  64                 char *name_type = NULL;
  65                 char *name = NULL;
  66                 char *next_name = NULL;
  67                 char *ip = NULL;
  68                 char *port = NULL;
  69
  70                 const char *ptr;
  71                 int count = 0;
  72
  73                 if (!fgets_slash(line,sizeof(line),fp)) {
  74                         continue;
  75                 }
  76
  77                 if (*line == '#') {
  78                         continue;
  79                 }
  80
  81                 ptr = line;
  82
  83                 if (next_token_talloc(ctx, &ptr, &name_type, NULL))
  84                         ++count;
  85                 if (next_token_talloc(ctx, &ptr, &name, NULL))
  86                         ++count;
  87                 if (strcasecmp(name_type, "A") == 0) {
  88                         if (next_token_talloc(ctx, &ptr, &ip, NULL))
  89                                 ++count;
  90                 } else if (strcasecmp(name_type, "SRV") == 0) {
  91                         if (next_token_talloc(ctx, &ptr, &next_name, NULL))
  92                                 ++count;
  93                         if (next_token_talloc(ctx, &ptr, &port, NULL))
  94                                 ++count;
  95                 } else if (strcasecmp(name_type, "CNAME") == 0) {
  96                         if (next_token_talloc(ctx, &ptr, &next_name, NULL))
  97                                 ++count;
  98                 }
  99                 if (count <= 0)
 100                         continue;
 101
 102                 if (strcasecmp(name_type, "A") == 0) {
 103                         if (count != 3) {
 104                                 DEBUG(0,("getdns_hosts_fileent: Ill formed hosts A record [%s]\n",
 105                                          line));
 106                                 continue;
 107                         }
 108                         DEBUG(4, ("getdns_hosts_fileent: host entry: %s %s %s\n",
 109                                   name_type, name, ip));
 110                         if (!interpret_string_addr(pss, ip, AI_NUMERICHOST)) {
 111                                 DEBUG(0,("getdns_hosts_fileent: invalid address "
 112                                          "%s.\n", ip));
 113                         }
 114
 115                 } else if (strcasecmp(name_type, "SRV") == 0) {
 116                         if (count != 4) {
 117                                 DEBUG(0,("getdns_hosts_fileent: Ill formed hosts SRV record [%s]\n",
 118                                          line));
 119                                 continue;
 120                         }
 121                         *p_port = strtoul(port, NULL, 10);
 122                         if (*p_port == UINT32_MAX) {
 123                                 DEBUG(0, ("getdns_hosts_fileent: Ill formed hosts SRV record [%s] (invalid port: %s)\n",
 124                                           line, port));
 125                                 continue;
 126                         }
 127                         DEBUG(4, ("getdns_hosts_fileent: host entry: %s %s %s %u\n",
 128                                   name_type, name, next_name, (unsigned int)*p_port));
 129                         *pp_next_name = talloc_strdup(ctx, next_name);
 130                         if (!*pp_next_name) {
 131                                 return false;
 132                         }
 133                 } else if (strcasecmp(name_type, "CNAME") == 0) {
 134                         if (count != 3) {
 135                                 DEBUG(0,("getdns_hosts_fileent: Ill formed hosts CNAME record [%s]\n",
 136                                          line));
 137                                 continue;
 138                         }
 139                         DEBUG(4, ("getdns_hosts_fileent: host entry: %s %s %s\n",
 140                                   name_type, name, next_name));
 141                         *pp_next_name = talloc_strdup(ctx, next_name);
 142                         if (!*pp_next_name) {
 143                                 return false;
 144                         }
 145                 } else {
 146                         DEBUG(0,("getdns_hosts_fileent: unknown type %s\n", name_type));
 147                         continue;
 148                 }
 149
 150                 *pp_name = talloc_strdup(ctx, name);
 151                 if (!*pp_name) {
 152                         return false;
 153                 }
 154
 155                 *pp_name_type = talloc_strdup(ctx, name_type);
 156                 if (!*pp_name_type) {
 157                         return false;
 158                 }
 159                 return true;
 160         }
 161
 162         return false;
 163 }
 164
 165 /********************************************************
 166  Finish parsing the dns_hosts_file file.
 167 *********************************************************/
 168
 169 static void enddns_hosts_file(XFILE *fp)
 170 {
 171         x_fclose(fp);
 172 }
 173
 174 /********************************************************
 175  Resolve via "dns_hosts" method.
 176 *********************************************************/
 177
 178 static NTSTATUS resolve_dns_hosts_file_as_sockaddr_recurse(const char *dns_hosts_file,
 179                                                            const char *name, bool srv_lookup,
 180                                                            int level, uint32_t port,
 181                                                            TALLOC_CTX *mem_ctx,
 182                                                            struct sockaddr_storage **return_iplist,
 183                                                            int *return_count)
 184 {
 185         /*
 186          * "dns_hosts" means parse the local dns_hosts file.
 187          */
 188
 189         XFILE *fp;
 190         char *host_name = NULL;
 191         char *name_type = NULL;
 192         char *next_name = NULL;
 193         struct sockaddr_storage return_ss;
 194         uint32_t srv_port;
 195         NTSTATUS status = NT_STATUS_OBJECT_NAME_NOT_FOUND;
 196         TALLOC_CTX *ctx = NULL;
 197         TALLOC_CTX *ip_list_ctx = NULL;
 198
 199         /* Don't recurse forever, even on our own flat files */
 200         if (level > 11) {
 201
 202         }
 203
 204         *return_iplist = NULL;
 205         *return_count = 0;
 206
 207         DEBUG(3,("resolve_dns_hosts: "
 208                 "Attempting dns_hosts lookup for name %s\n",
 209                 name));
 210
 211         fp = startdns_hosts_file(dns_hosts_file);
 212
 213         if ( fp == NULL )
 214                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 215
 216         ip_list_ctx = talloc_new(mem_ctx);
 217         if (!ip_list_ctx) {
 218                 enddns_hosts_file(fp);
 219                 return NT_STATUS_NO_MEMORY;
 220         }
 221
 222         ctx = talloc_new(ip_list_ctx);
 223         if (!ctx) {
 224                 talloc_free(ip_list_ctx);
 225                 enddns_hosts_file(fp);
 226                 return NT_STATUS_NO_MEMORY;
 227         }
 228
 229         while (getdns_hosts_fileent(ctx, fp, &host_name, &name_type, &next_name, &return_ss, &srv_port)) {
 230                 if (!strequal(name, host_name)) {
 231                         TALLOC_FREE(ctx);
 232                         ctx = talloc_new(mem_ctx);
 233                         if (!ctx) {
 234                                 enddns_hosts_file(fp);
 235                                 return NT_STATUS_NO_MEMORY;
 236                         }
 237
 238                         continue;
 239                 }
 240
 241                 if (srv_lookup) {
 242                         if (strcasecmp(name_type, "SRV") == 0) {
 243                                 /* we only accept one host name per SRV entry */
 244                                 enddns_hosts_file(fp);
 245                                 status = resolve_dns_hosts_file_as_sockaddr_recurse(dns_hosts_file, next_name,
 246                                                                                     false,
 247                                                                                     level + 1, srv_port,
 248                                                                                     mem_ctx, return_iplist,
 249                                                                                     return_count);
 250                                 talloc_free(ip_list_ctx);
 251                                 return status;
 252                         } else {
 253                                 continue;
 254                         }
 255                 } else if (strcasecmp(name_type, "CNAME") == 0) {
 256                         /* we only accept one host name per CNAME */
 257                         enddns_hosts_file(fp);
 258                         status = resolve_dns_hosts_file_as_sockaddr_recurse(dns_hosts_file, next_name, false,
 259                                                                             level + 1, port,
 260                                                                             mem_ctx, return_iplist, return_count);
 261                         talloc_free(ip_list_ctx);
 262                         return status;
 263                 } else if (strcasecmp(name_type, "A") == 0) {
 264                         /* Set the specified port (possibly from a SRV lookup) into the structure we return */
 265                         set_sockaddr_port((struct sockaddr *)&return_ss, port);
 266
 267                         /* We are happy to keep looking for other possible A record matches */
 268                         *return_iplist = talloc_realloc(ip_list_ctx, (*return_iplist),
 269                                                         struct sockaddr_storage,
 270                                                         (*return_count)+1);
 271
 272                         if ((*return_iplist) == NULL) {
 273                                 TALLOC_FREE(ctx);
 274                                 enddns_hosts_file(fp);
 275                                 DEBUG(3,("resolve_dns_hosts: talloc_realloc fail !\n"));
 276                                 return NT_STATUS_NO_MEMORY;
 277                         }
 278
 279                         (*return_iplist)[*return_count] = return_ss;
 280                         *return_count += 1;
 281
 282                         /* we found something */
 283                         status = NT_STATUS_OK;
 284                 }
 285         }
 286
 287         talloc_steal(mem_ctx, *return_iplist);
 288         TALLOC_FREE(ip_list_ctx);
 289         enddns_hosts_file(fp);
 290         return status;
 291 }
 292
 293 /********************************************************
 294  Resolve via "dns_hosts" method.
 295 *********************************************************/
 296
 297 NTSTATUS resolve_dns_hosts_file_as_sockaddr(const char *dns_hosts_file,
 298                                             const char *name, bool srv_lookup,
 299                                             TALLOC_CTX *mem_ctx,
 300                                             struct sockaddr_storage **return_iplist,
 301                                             int *return_count)
 302 {
 303         return resolve_dns_hosts_file_as_sockaddr_recurse(dns_hosts_file, name, srv_lookup,
 304                                                           0, 0,
 305                                                           mem_ctx, return_iplist, return_count);
 306 }