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                 if(result)
  43                         return result;
  44         }
  45
  46         if(m)
  47                 return (a[i] & (0x100 - (1 << (8 - m)))) -
  48                         (b[i] & (0x100 - (1 << (8 - m))));
  49
  50         return 0;
  51 }
  52
  53 void mask(void *va, int masklen, int len) {
  54         int i;
  55         char *a = va;
  56
  57         i = masklen / 8;
  58         masklen %= 8;
  59
  60         if(masklen)
  61                 a[i++] &= (0x100 - (1 << (8 - masklen)));
  62
  63         for(; i < len; i++)
  64                 a[i] = 0;
  65 }
  66
  67 void maskcpy(void *va, const void *vb, int masklen, int len) {
  68         int i, m;
  69         char *a = va;
  70         const char *b = vb;
  71
  72         for(m = masklen, i = 0; m >= 8; m -= 8, i++)
  73                 a[i] = b[i];
  74
  75         if(m) {
  76                 a[i] = b[i] & (0x100 - (1 << (8 - m)));
  77                 i++;
  78         }
  79
  80         for(; i < len; i++)
  81                 a[i] = 0;
  82 }
  83
  84 bool maskcheck(const void *va, int masklen, int len) {
  85         int i;
  86         const char *a = va;
  87
  88         i = masklen / 8;
  89         masklen %= 8;
  90
  91         if(masklen && a[i++] & (0xff >> masklen))
  92                 return false;
  93
  94         for(; i < len; i++)
  95                 if(a[i] != 0)
  96                         return false;
  97
  98         return true;
  99 }
 100
 101 /* Subnet comparison */
 102
 103 static int subnet_compare_mac(const subnet_t *a, const subnet_t *b) {
 104         int result;
 105
 106         result = memcmp(&a->net.mac.address, &b->net.mac.address, sizeof a->net.mac.address);
 107
 108         if(result)
 109                 return result;
 110
 111         result = a->weight - b->weight;
 112
 113         if(result || !a->owner || !b->owner)
 114                 return result;
 115
 116         return strcmp(a->owner->name, b->owner->name);
 117 }
 118
 119 static int subnet_compare_ipv4(const subnet_t *a, const subnet_t *b) {
 120         int result;
 121
 122         result = b->net.ipv4.prefixlength - a->net.ipv4.prefixlength;
 123
 124         if(result)
 125                 return result;
 126
 127         result = memcmp(&a->net.ipv4.address, &b->net.ipv4.address, sizeof(ipv4_t));
 128
 129         if(result)
 130                 return result;
 131
 132         result = a->weight - b->weight;
 133
 134         if(result || !a->owner || !b->owner)
 135                 return result;
 136
 137         return strcmp(a->owner->name, b->owner->name);
 138 }
 139
 140 static int subnet_compare_ipv6(const subnet_t *a, const subnet_t *b) {
 141         int result;
 142
 143         result = b->net.ipv6.prefixlength - a->net.ipv6.prefixlength;
 144
 145         if(result)
 146                 return result;
 147
 148         result = memcmp(&a->net.ipv6.address, &b->net.ipv6.address, sizeof(ipv6_t));
 149
 150         if(result)
 151                 return result;
 152
 153         result = a->weight - b->weight;
 154
 155         if(result || !a->owner || !b->owner)
 156                 return result;
 157
 158         return strcmp(a->owner->name, b->owner->name);
 159 }
 160
 161 int subnet_compare(const subnet_t *a, const subnet_t *b) {
 162         int result;
 163
 164         result = a->type - b->type;
 165
 166         if(result)
 167                 return result;
 168
 169         switch (a->type) {
 170         case SUBNET_MAC:
 171                 return subnet_compare_mac(a, b);
 172         case SUBNET_IPV4:
 173                 return subnet_compare_ipv4(a, b);
 174         case SUBNET_IPV6:
 175                 return subnet_compare_ipv6(a, b);
 176         default:
 177                 logger(DEBUG_ALWAYS, LOG_ERR, "subnet_compare() was called with unknown subnet type %d, exitting!", a->type);
 178                 exit(1);
 179         }
 180
 181         return 0;
 182 }
 183
 184 /* Ascii representation of subnets */
 185
 186 bool str2net(subnet_t *subnet, const char *subnetstr) {
 187         char str[1024];
 188         strncpy(str, subnetstr, sizeof(str));
 189         str[sizeof str - 1] = 0;
 190         int consumed;
 191
 192         int weight = DEFAULT_WEIGHT;
 193         char *weight_separator = strchr(str, '#');
 194         if (weight_separator) {
 195                 char *weight_str = weight_separator + 1;
 196                 if (sscanf(weight_str, "%d%n", &weight, &consumed) < 1)
 197                         return false;
 198                 if (weight_str[consumed])
 199                         return false;
 200                 *weight_separator = 0;
 201         }
 202
 203         int prefixlength = -1;
 204         char *prefixlength_separator = strchr(str, '/');
 205         if (prefixlength_separator) {
 206                 char* prefixlength_str = prefixlength_separator + 1;
 207                 if (sscanf(prefixlength_str, "%d%n", &prefixlength, &consumed) < 1)
 208                         return false;
 209                 if (prefixlength_str[consumed])
 210                         return false;
 211                 *prefixlength_separator = 0;
 212
 213                 if (prefixlength < 0)
 214                         return false;
 215         }
 216
 217         uint16_t x[8];
 218         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]) {
 219                 /*
 220                    Normally we should check that each part has two digits to prevent ambiguities.
 221                    However, in old tinc versions net2str() will agressively return MAC addresses with one-digit parts,
 222                    so we have to accept them otherwise we would be unable to parse ADD_SUBNET messages.
 223                 */
 224                 if (prefixlength >= 0)
 225                         return false;
 226
 227                 subnet->type = SUBNET_MAC;
 228                 subnet->weight = weight;
 229                 for(int i = 0; i < 6; i++)
 230                         subnet->net.mac.address.x[i] = x[i];
 231                 return true;
 232         }
 233
 234         if (sscanf(str, "%hu.%hu.%hu.%hu%n", &x[0], &x[1], &x[2], &x[3], &consumed) >= 4 && !str[consumed]) {
 235                 if (prefixlength == -1)
 236                         prefixlength = 32;
 237                 if (prefixlength > 32)
 238                         return false;
 239
 240                 subnet->type = SUBNET_IPV4;
 241                 subnet->net.ipv4.prefixlength = prefixlength;
 242                 subnet->weight = weight;
 243                 for(int i = 0; i < 4; i++) {
 244                         if (x[i] > 255)
 245                                 return false;
 246                         subnet->net.ipv4.address.x[i] = x[i];
 247                 }
 248                 return true;
 249         }
 250
 251         /* IPv6 */
 252
 253         char* last_colon = strrchr(str, ':');
 254         if (last_colon && sscanf(last_colon, ":%hu.%hu.%hu.%hu%n", &x[0], &x[1], &x[2], &x[3], &consumed) >= 4 && !last_colon[consumed]) {
 255                 /* Dotted quad suffix notation, convert to standard IPv6 notation */
 256                 for (int i = 0; i < 4; i++)
 257                         if (x[i] > 255)
 258                                 return false;
 259                 snprintf(last_colon, sizeof str - (last_colon - str), ":%02x%02x:%02x%02x", x[0], x[1], x[2], x[3]);
 260         }
 261
 262         char* double_colon = strstr(str, "::");
 263         if (double_colon) {
 264                 /* Figure out how many zero groups we need to expand */
 265                 int zero_group_count = 8;
 266                 for (const char* cur = str; *cur; cur++)
 267                         if (*cur != ':') {
 268                                 zero_group_count--;
 269                                 while(cur[1] && cur[1] != ':')
 270                                         cur++;
 271                         }
 272                 if (zero_group_count < 1)
 273                         return false;
 274
 275                 /* Split the double colon in the middle to make room for zero groups */
 276                 double_colon++;
 277                 memmove(double_colon + (zero_group_count * 2 - 1), double_colon, strlen(double_colon) + 1);
 278
 279                 /* Write zero groups in the resulting gap, overwriting the second colon */
 280                 for (int i = 0; i < zero_group_count; i++)
 281                         memcpy(&double_colon[i * 2], "0:", 2);
 282
 283                 /* Remove any leading or trailing colons */
 284                 if (str[0] == ':')
 285                         memmove(&str[0], &str[1], strlen(&str[1]) + 1);
 286                 if (str[strlen(str) - 1] == ':')
 287                         str[strlen(str) - 1] = 0;
 288         }
 289
 290         if (sscanf(str, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx%n",
 291                 &x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &x[6], &x[7], &consumed) >= 8 && !str[consumed]) {
 292                 if (prefixlength == -1)
 293                         prefixlength = 128;
 294                 if (prefixlength > 128)
 295                         return false;
 296
 297                 subnet->type = SUBNET_IPV6;
 298                 subnet->net.ipv6.prefixlength = prefixlength;
 299                 subnet->weight = weight;
 300                 for(int i = 0; i < 8; i++)
 301                         subnet->net.ipv6.address.x[i] = htons(x[i]);
 302                 return true;
 303         }
 304
 305         return false;
 306 }
 307
 308 bool net2str(char *netstr, int len, const subnet_t *subnet) {
 309         if(!netstr || !subnet) {
 310                 logger(DEBUG_ALWAYS, LOG_ERR, "net2str() was called with netstr=%p, subnet=%p!", netstr, subnet);
 311                 return false;
 312         }
 313
 314         int result;
 315         int prefixlength = -1;
 316         switch (subnet->type) {
 317                 case SUBNET_MAC:
 318                         result = snprintf(netstr, len, "%02x:%02x:%02x:%02x:%02x:%02x",
 319                                          subnet->net.mac.address.x[0],
 320                                          subnet->net.mac.address.x[1],
 321                                          subnet->net.mac.address.x[2],
 322                                          subnet->net.mac.address.x[3],
 323                                          subnet->net.mac.address.x[4],
 324                                          subnet->net.mac.address.x[5]);
 325                         netstr += result;
 326                         len -= result;
 327                         break;
 328
 329                 case SUBNET_IPV4:
 330                         result = snprintf(netstr, len, "%u.%u.%u.%u",
 331                                          subnet->net.ipv4.address.x[0],
 332                                          subnet->net.ipv4.address.x[1],
 333                                          subnet->net.ipv4.address.x[2],
 334                                          subnet->net.ipv4.address.x[3]);
 335                         netstr += result;
 336                         len -= result;
 337                         prefixlength = subnet->net.ipv4.prefixlength;
 338                         if (prefixlength == 32)
 339                                 prefixlength = -1;
 340                         break;
 341
 342                 case SUBNET_IPV6: {
 343                         /* Find the longest sequence of consecutive zeroes */
 344                         int max_zero_length = 0;
 345                         int max_zero_length_index = 0;
 346                         int current_zero_length = 0;
 347                         int current_zero_length_index = 0;
 348                         for (int i = 0; i < 8; i++) {
 349                                 if (subnet->net.ipv6.address.x[i] != 0)
 350                                         current_zero_length = 0;
 351                                 else {
 352                                         if (current_zero_length == 0)
 353                                                 current_zero_length_index = i;
 354                                         current_zero_length++;
 355                                         if (current_zero_length > max_zero_length) {
 356                                                 max_zero_length = current_zero_length;
 357                                                 max_zero_length_index = current_zero_length_index;
 358                                         }
 359                                 }
 360                         }
 361
 362                         /* Print the address */
 363                         for (int i = 0; i < 8;) {
 364                                 if (max_zero_length > 1 && max_zero_length_index == i) {
 365                                         /* Shorten the representation as per RFC 5952 */
 366                                         const char* const FORMATS[] = { "%.1s", "%.2s", "%.3s" };
 367                                         const char* const* format = &FORMATS[0];
 368                                         if (i == 0)
 369                                                 format++;
 370                                         if (i + max_zero_length == 8)
 371                                                 format++;
 372                                         result = snprintf(netstr, len, *format, ":::");
 373                                         i += max_zero_length;
 374                                 } else {
 375                                         result = snprintf(netstr, len, "%hx:", ntohs(subnet->net.ipv6.address.x[i]));
 376                                         i++;
 377                                 }
 378                                 netstr += result;
 379                                 len -= result;
 380                         }
 381
 382                         /* Remove the trailing colon */
 383                         netstr--;
 384                         len++;
 385                         *netstr = 0;
 386
 387                         prefixlength = subnet->net.ipv6.prefixlength;
 388                         if (prefixlength == 128)
 389                                 prefixlength = -1;
 390                         break;
 391                 }
 392
 393                 default:
 394                         logger(DEBUG_ALWAYS, LOG_ERR, "net2str() was called with unknown subnet type %d, exiting!", subnet->type);
 395                         exit(1);
 396         }
 397
 398         if (prefixlength >= 0) {
 399                 result = snprintf(netstr, len, "/%d", prefixlength);
 400                 netstr += result;
 401                 len -= result;
 402         }
 403
 404         if (subnet->weight != DEFAULT_WEIGHT) {
 405                 snprintf(netstr, len, "#%d", subnet->weight);
 406                 netstr += result;
 407                 len -= result;
 408         }
 409
 410         return true;
 411 }