librpc/ndr/ndr_dns.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    manipulate dns name structures
   5
   6    Copyright (C) 2010 Kai Blin  <kai@samba.org>
   7
   8    Heavily based on nbtname.c which is:
   9
  10    Copyright (C) Andrew Tridgell 2005
  11
  12    This program is free software; you can redistribute it and/or modify
  13    it under the terms of the GNU General Public License as published by
  14    the Free Software Foundation; either version 3 of the License, or
  15    (at your option) any later version.
  16
  17    This program is distributed in the hope that it will be useful,
  18    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20    GNU General Public License for more details.
  21
  22    You should have received a copy of the GNU General Public License
  23    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  24 */
  25
  26 /*
  27   see rfc1002 for the detailed format of compressed names
  28 */
  29
  30 #include "includes.h"
  31 #include "librpc/gen_ndr/ndr_dns.h"
  32 #include "librpc/gen_ndr/ndr_misc.h"
  33 #include "system/locale.h"
  34 #include "lib/util/util_net.h"
  35
  36 /* don't allow an unlimited number of name components */
  37 #define MAX_COMPONENTS 128
  38
  39 /**
  40   print a dns string
  41 */
  42 _PUBLIC_ void ndr_print_dns_string(struct ndr_print *ndr,
  43                                    const char *name,
  44                                    const char *s)
  45 {
  46         ndr_print_string(ndr, name, s);
  47 }
  48
  49 /*
  50   pull one component of a dns_string
  51 */
  52 static enum ndr_err_code ndr_pull_component(struct ndr_pull *ndr,
  53                                             uint8_t **component,
  54                                             uint32_t *offset,
  55                                             uint32_t *max_offset)
  56 {
  57         uint8_t len;
  58         unsigned int loops = 0;
  59         while (loops < 5) {
  60                 if (*offset >= ndr->data_size) {
  61                         return ndr_pull_error(ndr, NDR_ERR_STRING,
  62                                         "BAD DNS NAME component, bad offset");
  63                 }
  64                 len = ndr->data[*offset];
  65                 if (len == 0) {
  66                         *offset += 1;
  67                         *max_offset = MAX(*max_offset, *offset);
  68                         *component = NULL;
  69                         return NDR_ERR_SUCCESS;
  70                 }
  71                 if ((len & 0xC0) == 0xC0) {
  72                         /* its a label pointer */
  73                         if (1 + *offset >= ndr->data_size) {
  74                                 return ndr_pull_error(ndr, NDR_ERR_STRING,
  75                                                 "BAD DNS NAME component, " \
  76                                                 "bad label offset");
  77                         }
  78                         *max_offset = MAX(*max_offset, *offset + 2);
  79                         *offset = ((len&0x3F)<<8) | ndr->data[1 + *offset];
  80                         *max_offset = MAX(*max_offset, *offset);
  81                         loops++;
  82                         continue;
  83                 }
  84                 if ((len & 0xC0) != 0) {
  85                         /* its a reserved length field */
  86                         return ndr_pull_error(ndr, NDR_ERR_STRING,
  87                                               "BAD DNS NAME component, " \
  88                                               "reserved length field: 0x%02x",
  89                                               (len &0xC));
  90                 }
  91                 if (*offset + len + 1 > ndr->data_size) {
  92                         return ndr_pull_error(ndr, NDR_ERR_STRING,
  93                                               "BAD DNS NAME component, "\
  94                                               "length too long");
  95                 }
  96                 *component = (uint8_t*)talloc_strndup(ndr,
  97                                 (const char *)&ndr->data[1 + *offset], len);
  98                 NDR_ERR_HAVE_NO_MEMORY(*component);
  99                 *offset += len + 1;
 100                 *max_offset = MAX(*max_offset, *offset);
 101                 return NDR_ERR_SUCCESS;
 102         }
 103
 104         /* too many pointers */
 105         return ndr_pull_error(ndr, NDR_ERR_STRING,
 106                               "BAD DNS NAME component, too many pointers");
 107 }
 108
 109 /**
 110   pull a dns_string from the wire
 111 */
 112 _PUBLIC_ enum ndr_err_code ndr_pull_dns_string(struct ndr_pull *ndr,
 113                                                int ndr_flags,
 114                                                const char **s)
 115 {
 116         uint32_t offset = ndr->offset;
 117         uint32_t max_offset = offset;
 118         unsigned num_components;
 119         char *name;
 120
 121         if (!(ndr_flags & NDR_SCALARS)) {
 122                 return NDR_ERR_SUCCESS;
 123         }
 124
 125         name = talloc_strdup(ndr->current_mem_ctx, "");
 126
 127         /* break up name into a list of components */
 128         for (num_components=0; num_components<MAX_COMPONENTS;
 129              num_components++) {
 130                 uint8_t *component = NULL;
 131                 NDR_CHECK(ndr_pull_component(ndr, &component, &offset,
 132                                              &max_offset));
 133                 if (component == NULL) break;
 134                 if (num_components > 0) {
 135                         name = talloc_asprintf_append_buffer(name, ".%s",
 136                                                              component);
 137                 } else {
 138                         name = talloc_asprintf_append_buffer(name, "%s",
 139                                                              component);
 140                 }
 141                 NDR_ERR_HAVE_NO_MEMORY(name);
 142         }
 143         if (num_components == MAX_COMPONENTS) {
 144                 return ndr_pull_error(ndr, NDR_ERR_STRING,
 145                                       "BAD DNS NAME too many components");
 146         }
 147
 148         (*s) = name;
 149         ndr->offset = max_offset;
 150
 151         return NDR_ERR_SUCCESS;
 152 }
 153
 154 /**
 155   push a dns string to the wire
 156 */
 157 _PUBLIC_ enum ndr_err_code ndr_push_dns_string(struct ndr_push *ndr,
 158                                                int ndr_flags,
 159                                                const char *s)
 160 {
 161         if (!(ndr_flags & NDR_SCALARS)) {
 162                 return NDR_ERR_SUCCESS;
 163         }
 164
 165         while (s && *s) {
 166                 enum ndr_err_code ndr_err;
 167                 char *compname;
 168                 size_t complen;
 169                 uint32_t offset;
 170
 171                 /* see if we have pushed the remaing string allready,
 172                  * if so we use a label pointer to this string
 173                  */
 174                 ndr_err = ndr_token_retrieve_cmp_fn(&ndr->dns_string_list, s,
 175                                                     &offset,
 176                                                     (comparison_fn_t)strcmp,
 177                                                     false);
 178                 if (NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 179                         uint8_t b[2];
 180
 181                         if (offset > 0x3FFF) {
 182                                 return ndr_push_error(ndr, NDR_ERR_STRING,
 183                                                       "offset for dns string " \
 184                                                       "label pointer " \
 185                                                       "%u[%08X] > 0x00003FFF",
 186                                                       offset, offset);
 187                         }
 188
 189                         b[0] = 0xC0 | (offset>>8);
 190                         b[1] = (offset & 0xFF);
 191
 192                         return ndr_push_bytes(ndr, b, 2);
 193                 }
 194
 195                 complen = strcspn(s, ".");
 196
 197                 /* we need to make sure the length fits into 6 bytes */
 198                 if (complen > 0x3F) {
 199                         return ndr_push_error(ndr, NDR_ERR_STRING,
 200                                               "component length %u[%08X] > " \
 201                                               "0x0000003F",
 202                                               (unsigned)complen,
 203                                               (unsigned)complen);
 204                 }
 205
 206                 compname = talloc_asprintf(ndr, "%c%*.*s",
 207                                                 (unsigned char)complen,
 208                                                 (unsigned char)complen,
 209                                                 (unsigned char)complen, s);
 210                 NDR_ERR_HAVE_NO_MEMORY(compname);
 211
 212                 /* remember the current componemt + the rest of the string
 213                  * so it can be reused later
 214                  */
 215                 NDR_CHECK(ndr_token_store(ndr, &ndr->dns_string_list, s,
 216                                           ndr->offset));
 217
 218                 /* push just this component into the blob */
 219                 NDR_CHECK(ndr_push_bytes(ndr, (const uint8_t *)compname,
 220                                          complen+1));
 221                 talloc_free(compname);
 222
 223                 s += complen;
 224                 if (*s == '.') s++;
 225         }
 226
 227         /* if we reach the end of the string and have pushed the last component
 228          * without using a label pointer, we need to terminate the string
 229          */
 230         return ndr_push_bytes(ndr, (const uint8_t *)"", 1);
 231 }
 232
 233 _PUBLIC_ enum ndr_err_code ndr_push_dns_res_rec(struct ndr_push *ndr,
 234                                                 int ndr_flags,
 235                                                 const struct dns_res_rec *r)
 236 {
 237         uint32_t _flags_save_STRUCT = ndr->flags;
 238         uint32_t _saved_offset1, _saved_offset2;
 239         uint16_t length;
 240         ndr_set_flags(&ndr->flags, LIBNDR_PRINT_ARRAY_HEX |
 241                                    LIBNDR_FLAG_NOALIGN);
 242         if (ndr_flags & NDR_SCALARS) {
 243                 NDR_CHECK(ndr_push_align(ndr, 4));
 244                 NDR_CHECK(ndr_push_dns_string(ndr, NDR_SCALARS, r->name));
 245                 NDR_CHECK(ndr_push_dns_qtype(ndr, NDR_SCALARS, r->rr_type));
 246                 NDR_CHECK(ndr_push_dns_qclass(ndr, NDR_SCALARS, r->rr_class));
 247                 NDR_CHECK(ndr_push_uint32(ndr, NDR_SCALARS, r->ttl));
 248                 _saved_offset1 = ndr->offset;
 249                 NDR_CHECK(ndr_push_uint16(ndr, NDR_SCALARS, 0));
 250                 if (r->length > 0) {
 251                         NDR_CHECK(ndr_push_set_switch_value(ndr, &r->rdata,
 252                                                             r->rr_type));
 253                         NDR_CHECK(ndr_push_dns_rdata(ndr, NDR_SCALARS,
 254                                                      &r->rdata));
 255                         if (r->unexpected.length > 0) {
 256                                 return ndr_push_error(ndr,
 257                                                       NDR_ERR_LENGTH,
 258                                                       "Invalid...Unexpected " \
 259                                                       "blob length is too " \
 260                                                       "large");
 261                         }
 262                 }
 263                 if (r->unexpected.length > UINT16_MAX) {
 264                         return ndr_push_error(ndr, NDR_ERR_LENGTH,
 265                                               "Unexpected blob length "\
 266                                               "is too large");
 267                 }
 268
 269                 NDR_CHECK(ndr_push_bytes(ndr, r->unexpected.data,
 270                                          r->unexpected.length));
 271                 NDR_CHECK(ndr_push_trailer_align(ndr, 4));
 272                 length = ndr->offset - (_saved_offset1 + 2);
 273                 _saved_offset2 = ndr->offset;
 274                 ndr->offset = _saved_offset1;
 275                 NDR_CHECK(ndr_push_uint16(ndr, NDR_SCALARS, length));
 276                 ndr->offset = _saved_offset2;
 277         }
 278         if (ndr_flags & NDR_BUFFERS) {
 279                 NDR_CHECK(ndr_push_dns_rdata(ndr, NDR_BUFFERS,
 280                                              &r->rdata));
 281         }
 282         ndr->flags = _flags_save_STRUCT;
 283         return NDR_ERR_SUCCESS;
 284 }
 285
 286 _PUBLIC_ enum ndr_err_code ndr_pull_dns_res_rec(struct ndr_pull *ndr,
 287                                                 int ndr_flags,
 288                                                 struct dns_res_rec *r)
 289 {
 290         uint32_t _flags_save_STRUCT = ndr->flags;
 291         uint32_t _saved_offset1;
 292         uint32_t pad, length;
 293
 294         ndr_set_flags(&ndr->flags, LIBNDR_PRINT_ARRAY_HEX |
 295                                    LIBNDR_FLAG_NOALIGN);
 296         if (ndr_flags & NDR_SCALARS) {
 297                 NDR_CHECK(ndr_pull_align(ndr, 4));
 298                 NDR_CHECK(ndr_pull_dns_string(ndr, NDR_SCALARS, &r->name));
 299                 NDR_CHECK(ndr_pull_dns_qtype(ndr, NDR_SCALARS, &r->rr_type));
 300                 NDR_CHECK(ndr_pull_dns_qclass(ndr, NDR_SCALARS, &r->rr_class));
 301                 NDR_CHECK(ndr_pull_uint32(ndr, NDR_SCALARS, &r->ttl));
 302                 NDR_CHECK(ndr_pull_uint16(ndr, NDR_SCALARS, &r->length));
 303                 _saved_offset1 = ndr->offset;
 304                 if (r->length > 0) {
 305                         NDR_CHECK(ndr_pull_set_switch_value(ndr, &r->rdata,
 306                                                             r->rr_type));
 307                         NDR_CHECK(ndr_pull_dns_rdata(ndr, NDR_SCALARS,
 308                                                      &r->rdata));
 309                 } else {
 310                         ZERO_STRUCT(r->rdata);
 311                 }
 312                 length = ndr->offset - _saved_offset1;
 313                 if (length > r->length) {
 314                         return ndr_pull_error(ndr, NDR_ERR_LENGTH, "TODO");
 315                 }
 316
 317                 r->unexpected = data_blob_null;
 318                 pad = r->length - length;
 319                 if (pad > 0) {
 320                         NDR_PULL_NEED_BYTES(ndr, pad);
 321                         r->unexpected = data_blob_talloc(ndr->current_mem_ctx,
 322                                                          ndr->data +
 323                                                          ndr->offset,
 324                                                          pad);
 325                         if (r->unexpected.data == NULL) {
 326                                 return ndr_pull_error(ndr,
 327                                                       NDR_ERR_ALLOC,
 328                                                       "Failed to allocate a " \
 329                                                       "data blob");
 330                         }
 331                         ndr->offset += pad;
 332                 }
 333
 334
 335                 NDR_CHECK(ndr_pull_trailer_align(ndr, 4));
 336         }
 337         if (ndr_flags & NDR_BUFFERS) {
 338                 NDR_CHECK(ndr_pull_dns_rdata(ndr, NDR_BUFFERS, &r->rdata));
 339         }
 340         ndr->flags = _flags_save_STRUCT;
 341         return NDR_ERR_SUCCESS;
 342 }