tinc-vpn.org Git - tinc/blob - src/subnet_parse.c

   1 /*
   2     subnet_parse.c -- handle subnet parsing
   3     Copyright (C) 2000-2012 Guus Sliepen <guus@tinc-vpn.org>,
   4                   2000-2005 Ivo Timmermans
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License along
  17     with this program; if not, write to the Free Software Foundation, Inc.,
  18     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19 */
  20
  21 #include "system.h"
  22
  23 #include "logger.h"
  24 #include "net.h"
  25 #include "netutl.h"
  26 #include "subnet.h"
  27 #include "utils.h"
  28 #include "xalloc.h"
  29
  30 /* Changing this default will affect ADD_SUBNET messages - beware of inconsistencies between versions */
  31 static const int DEFAULT_WEIGHT = 10;
  32
  33 /* Subnet mask handling */
  34
  35 int maskcmp(const void *va, const void *vb, int masklen) {
  36         int i, m, result;
  37         const char *a = va;
  38         const char *b = vb;
  39
  40         for(m = masklen, i = 0; m >= 8; m -= 8, i++) {
  41                 result = a[i] - b[i];
  42
  43                 if(result) {
  44                         return result;
  45                 }
  46         }
  47
  48         if(m)
  49                 return (a[i] & (0x100 - (1 << (8 - m)))) -
  50                        (b[i] & (0x100 - (1 << (8 - m))));
  51
  52         return 0;
  53 }
  54
  55 void mask(void *va, int masklen, int len) {
  56         int i;
  57         char *a = va;
  58
  59         i = masklen / 8;
  60         masklen %= 8;
  61
  62         if(masklen) {
  63                 a[i++] &= (0x100 - (1 << (8 - masklen)));
  64         }
  65
  66         for(; i < len; i++) {
  67                 a[i] = 0;
  68         }
  69 }
  70
  71 void maskcpy(void *va, const void *vb, int masklen, int len) {
  72         int i, m;
  73         char *a = va;
  74         const char *b = vb;
  75
  76         for(m = masklen, i = 0; m >= 8; m -= 8, i++) {
  77                 a[i] = b[i];
  78         }
  79
  80         if(m) {
  81                 a[i] = b[i] & (0x100 - (1 << (8 - m)));
  82                 i++;
  83         }
  84
  85         for(; i < len; i++) {
  86                 a[i] = 0;
  87         }
  88 }
  89
  90 bool maskcheck(const void *va, int masklen, int len) {
  91         int i;
  92         const char *a = va;
  93
  94         i = masklen / 8;
  95         masklen %= 8;
  96
  97         if(masklen && a[i++] & (0xff >> masklen)) {
  98                 return false;
  99         }
 100
 101         for(; i < len; i++)
 102                 if(a[i] != 0) {
 103                         return false;
 104                 }
 105
 106         return true;
 107 }
 108
 109 /* Subnet comparison */
 110
 111 static int subnet_compare_mac(const subnet_t *a, const subnet_t *b) {
 112         int result;
 113
 114         result = memcmp(&a->net.mac.address, &b->net.mac.address, sizeof(a->net.mac.address));
 115
 116         if(result) {
 117                 return result;
 118         }
 119
 120         result = a->weight - b->weight;
 121
 122         if(result || !a->owner || !b->owner) {
 123                 return result;
 124         }
 125
 126         return strcmp(a->owner->name, b->owner->name);
 127 }
 128
 129 static int subnet_compare_ipv4(const subnet_t *a, const subnet_t *b) {
 130         int result;
 131
 132         result = b->net.ipv4.prefixlength - a->net.ipv4.prefixlength;
 133
 134         if(result) {
 135                 return result;
 136         }
 137
 138         result = memcmp(&a->net.ipv4.address, &b->net.ipv4.address, sizeof(ipv4_t));
 139
 140         if(result) {
 141                 return result;
 142         }
 143
 144         result = a->weight - b->weight;
 145
 146         if(result || !a->owner || !b->owner) {
 147                 return result;
 148         }
 149
 150         return strcmp(a->owner->name, b->owner->name);
 151 }
 152
 153 static int subnet_compare_ipv6(const subnet_t *a, const subnet_t *b) {
 154         int result;
 155
 156         result = b->net.ipv6.prefixlength - a->net.ipv6.prefixlength;
 157
 158         if(result) {
 159                 return result;
 160         }
 161
 162         result = memcmp(&a->net.ipv6.address, &b->net.ipv6.address, sizeof(ipv6_t));
 163
 164         if(result) {
 165                 return result;
 166         }
 167
 168         result = a->weight - b->weight;
 169
 170         if(result || !a->owner || !b->owner) {
 171                 return result;
 172         }
 173
 174         return strcmp(a->owner->name, b->owner->name);
 175 }
 176
 177 int subnet_compare(const subnet_t *a, const subnet_t *b) {
 178         int result;
 179
 180         result = a->type - b->type;
 181
 182         if(result) {
 183                 return result;
 184         }
 185
 186         switch(a->type) {
 187         case SUBNET_MAC:
 188                 return subnet_compare_mac(a, b);
 189
 190         case SUBNET_IPV4:
 191                 return subnet_compare_ipv4(a, b);
 192
 193         case SUBNET_IPV6:
 194                 return subnet_compare_ipv6(a, b);
 195
 196         default:
 197                 logger(DEBUG_ALWAYS, LOG_ERR, "subnet_compare() was called with unknown subnet type %d, exitting!", a->type);
 198                 exit(1);
 199         }
 200
 201         return 0;
 202 }
 203
 204 /* Ascii representation of subnets */
 205
 206 bool str2net(subnet_t *subnet, const char *subnetstr) {
 207         char str[1024];
 208         strncpy(str, subnetstr, sizeof(str));
 209         str[sizeof(str) - 1] = 0;
 210         int consumed;
 211
 212         int weight = DEFAULT_WEIGHT;
 213         char *weight_separator = strchr(str, '#');
 214
 215         if(weight_separator) {
 216                 char *weight_str = weight_separator + 1;
 217
 218                 if(sscanf(weight_str, "%d%n", &weight, &consumed) < 1) {
 219                         return false;
 220                 }
 221
 222                 if(weight_str[consumed]) {
 223                         return false;
 224                 }
 225
 226                 *weight_separator = 0;
 227         }
 228
 229         int prefixlength = -1;
 230         char *prefixlength_separator = strchr(str, '/');
 231
 232         if(prefixlength_separator) {
 233                 char *prefixlength_str = prefixlength_separator + 1;
 234
 235                 if(sscanf(prefixlength_str, "%d%n", &prefixlength, &consumed) < 1) {
 236                         return false;
 237                 }
 238
 239                 if(prefixlength_str[consumed]) {
 240                         return false;
 241                 }
 242
 243                 *prefixlength_separator = 0;
 244
 245                 if(prefixlength < 0) {
 246                         return false;
 247                 }
 248         }
 249
 250         uint16_t x[8];
 251
 252         if(sscanf(str, "%hx:%hx:%hx:%hx:%hx:%hx%n", &x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &consumed) >= 6 && !str[consumed]) {
 253                 /*
 254                    Normally we should check that each part has two digits to prevent ambiguities.
 255                    However, in old tinc versions net2str() will aggressively return MAC addresses with one-digit parts,
 256                    so we have to accept them otherwise we would be unable to parse ADD_SUBNET messages.
 257                 */
 258                 if(prefixlength >= 0) {
 259                         return false;
 260                 }
 261
 262                 subnet->type = SUBNET_MAC;
 263                 subnet->weight = weight;
 264
 265                 for(int i = 0; i < 6; i++) {
 266                         subnet->net.mac.address.x[i] = x[i];
 267                 }
 268
 269                 return true;
 270         }
 271
 272         if(sscanf(str, "%hu.%hu.%hu.%hu%n", &x[0], &x[1], &x[2], &x[3], &consumed) >= 4 && !str[consumed]) {
 273                 if(prefixlength == -1) {
 274                         prefixlength = 32;
 275                 }
 276
 277                 if(prefixlength > 32) {
 278                         return false;
 279                 }
 280
 281                 subnet->type = SUBNET_IPV4;
 282                 subnet->net.ipv4.prefixlength = prefixlength;
 283                 subnet->weight = weight;
 284
 285                 for(int i = 0; i < 4; i++) {
 286                         if(x[i] > 255) {
 287                                 return false;
 288                         }
 289
 290                         subnet->net.ipv4.address.x[i] = x[i];
 291                 }
 292
 293                 return true;
 294         }
 295
 296         /* IPv6 */
 297
 298         char *last_colon = strrchr(str, ':');
 299
 300         if(last_colon && sscanf(last_colon, ":%hu.%hu.%hu.%hu%n", &x[0], &x[1], &x[2], &x[3], &consumed) >= 4 && !last_colon[consumed]) {
 301                 /* Dotted quad suffix notation, convert to standard IPv6 notation */
 302                 for(int i = 0; i < 4; i++)
 303                         if(x[i] > 255) {
 304                                 return false;
 305                         }
 306
 307                 snprintf(last_colon, sizeof(str) - (last_colon - str), ":%02x%02x:%02x%02x", x[0], x[1], x[2], x[3]);
 308         }
 309
 310         char *double_colon = strstr(str, "::");
 311
 312         if(double_colon) {
 313                 /* Figure out how many zero groups we need to expand */
 314                 int zero_group_count = 8;
 315
 316                 for(const char *cur = str; *cur; cur++)
 317                         if(*cur != ':') {
 318                                 zero_group_count--;
 319
 320                                 while(cur[1] && cur[1] != ':') {
 321                                         cur++;
 322                                 }
 323                         }
 324
 325                 if(zero_group_count < 1) {
 326                         return false;
 327                 }
 328
 329                 /* Split the double colon in the middle to make room for zero groups */
 330                 double_colon++;
 331                 memmove(double_colon + (zero_group_count * 2 - 1), double_colon, strlen(double_colon) + 1);
 332
 333                 /* Write zero groups in the resulting gap, overwriting the second colon */
 334                 for(int i = 0; i < zero_group_count; i++) {
 335                         memcpy(&double_colon[i * 2], "0:", 2);
 336                 }
 337
 338                 /* Remove any leading or trailing colons */
 339                 if(str[0] == ':') {
 340                         memmove(&str[0], &str[1], strlen(&str[1]) + 1);
 341                 }
 342
 343                 if(str[strlen(str) - 1] == ':') {
 344                         str[strlen(str) - 1] = 0;
 345                 }
 346         }
 347
 348         if(sscanf(str, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx%n",
 349                         &x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &x[6], &x[7], &consumed) >= 8 && !str[consumed]) {
 350                 if(prefixlength == -1) {
 351                         prefixlength = 128;
 352                 }
 353
 354                 if(prefixlength > 128) {
 355                         return false;
 356                 }
 357
 358                 subnet->type = SUBNET_IPV6;
 359                 subnet->net.ipv6.prefixlength = prefixlength;
 360                 subnet->weight = weight;
 361
 362                 for(int i = 0; i < 8; i++) {
 363                         subnet->net.ipv6.address.x[i] = htons(x[i]);
 364                 }
 365
 366                 return true;
 367         }
 368
 369         return false;
 370 }
 371
 372 bool net2str(char *netstr, int len, const subnet_t *subnet) {
 373         if(!netstr || !subnet) {
 374                 logger(DEBUG_ALWAYS, LOG_ERR, "net2str() was called with netstr=%p, subnet=%p!", (void *)netstr, (void *)subnet);
 375                 return false;
 376         }
 377
 378         int result;
 379         int prefixlength = -1;
 380
 381         switch(subnet->type) {
 382         case SUBNET_MAC:
 383                 result = snprintf(netstr, len, "%02x:%02x:%02x:%02x:%02x:%02x",
 384                                   subnet->net.mac.address.x[0],
 385                                   subnet->net.mac.address.x[1],
 386                                   subnet->net.mac.address.x[2],
 387                                   subnet->net.mac.address.x[3],
 388                                   subnet->net.mac.address.x[4],
 389                                   subnet->net.mac.address.x[5]);
 390                 netstr += result;
 391                 len -= result;
 392                 break;
 393
 394         case SUBNET_IPV4:
 395                 result = snprintf(netstr, len, "%u.%u.%u.%u",
 396                                   subnet->net.ipv4.address.x[0],
 397                                   subnet->net.ipv4.address.x[1],
 398                                   subnet->net.ipv4.address.x[2],
 399                                   subnet->net.ipv4.address.x[3]);
 400                 netstr += result;
 401                 len -= result;
 402                 prefixlength = subnet->net.ipv4.prefixlength;
 403
 404                 if(prefixlength == 32) {
 405                         prefixlength = -1;
 406                 }
 407
 408                 break;
 409
 410         case SUBNET_IPV6: {
 411                 /* Find the longest sequence of consecutive zeroes */
 412                 int max_zero_length = 0;
 413                 int max_zero_length_index = 0;
 414                 int current_zero_length = 0;
 415                 int current_zero_length_index = 0;
 416
 417                 for(int i = 0; i < 8; i++) {
 418                         if(subnet->net.ipv6.address.x[i] != 0) {
 419                                 current_zero_length = 0;
 420                         } else {
 421                                 if(current_zero_length == 0) {
 422                                         current_zero_length_index = i;
 423                                 }
 424
 425                                 current_zero_length++;
 426
 427                                 if(current_zero_length > max_zero_length) {
 428                                         max_zero_length = current_zero_length;
 429                                         max_zero_length_index = current_zero_length_index;
 430                                 }
 431                         }
 432                 }
 433
 434                 /* Print the address */
 435                 for(int i = 0; i < 8;) {
 436                         if(max_zero_length > 1 && max_zero_length_index == i) {
 437                                 /* Shorten the representation as per RFC 5952 */
 438                                 const char *const FORMATS[] = { "%.1s", "%.2s", "%.3s" };
 439                                 const char *const *format = &FORMATS[0];
 440
 441                                 if(i == 0) {
 442                                         format++;
 443                                 }
 444
 445                                 if(i + max_zero_length == 8) {
 446                                         format++;
 447                                 }
 448
 449                                 result = snprintf(netstr, len, *format, ":::");
 450                                 i += max_zero_length;
 451                         } else {
 452                                 result = snprintf(netstr, len, "%x:", ntohs(subnet->net.ipv6.address.x[i]));
 453                                 i++;
 454                         }
 455
 456                         netstr += result;
 457                         len -= result;
 458                 }
 459
 460                 /* Remove the trailing colon */
 461                 netstr--;
 462                 len++;
 463                 *netstr = 0;
 464
 465                 prefixlength = subnet->net.ipv6.prefixlength;
 466
 467                 if(prefixlength == 128) {
 468                         prefixlength = -1;
 469                 }
 470
 471                 break;
 472         }
 473
 474         default:
 475                 logger(DEBUG_ALWAYS, LOG_ERR, "net2str() was called with unknown subnet type %d, exiting!", subnet->type);
 476                 exit(1);
 477         }
 478
 479         if(prefixlength >= 0) {
 480                 result = snprintf(netstr, len, "/%d", prefixlength);
 481                 netstr += result;
 482                 len -= result;
 483         }
 484
 485         if(subnet->weight != DEFAULT_WEIGHT) {
 486                 snprintf(netstr, len, "#%d", subnet->weight);
 487         }
 488
 489         return true;
 490 }