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

   1 /*
   2     subnet_parse.c -- handle subnet parsing
   3     Copyright (C) 2000-2021 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 "subnet.h"
  26
  27 /* Changing this default will affect ADD_SUBNET messages - beware of inconsistencies between versions */
  28 static const int DEFAULT_WEIGHT = 10;
  29
  30 /* Subnet mask handling */
  31
  32 int maskcmp(const void *va, const void *vb, int masklen) {
  33         int i, m, result;
  34         const char *a = va;
  35         const char *b = vb;
  36
  37         for(m = masklen, i = 0; m >= 8; m -= 8, i++) {
  38                 result = a[i] - b[i];
  39
  40                 if(result) {
  41                         return result;
  42                 }
  43         }
  44
  45         if(m)
  46                 return (a[i] & (0x100 - (1 << (8 - m)))) -
  47                        (b[i] & (0x100 - (1 << (8 - m))));
  48
  49         return 0;
  50 }
  51
  52 void mask(void *va, int masklen, int len) {
  53         int i;
  54         char *a = va;
  55
  56         i = masklen / 8;
  57         masklen %= 8;
  58
  59         if(masklen) {
  60                 a[i++] &= (0x100 - (1 << (8 - masklen)));
  61         }
  62
  63         for(; i < len; i++) {
  64                 a[i] = 0;
  65         }
  66 }
  67
  68 void maskcpy(void *va, const void *vb, int masklen, int len) {
  69         int i, m;
  70         char *a = va;
  71         const char *b = vb;
  72
  73         for(m = masklen, i = 0; m >= 8; m -= 8, i++) {
  74                 a[i] = b[i];
  75         }
  76
  77         if(m) {
  78                 a[i] = b[i] & (0x100 - (1 << (8 - m)));
  79                 i++;
  80         }
  81
  82         for(; i < len; i++) {
  83                 a[i] = 0;
  84         }
  85 }
  86
  87 bool subnetcheck(const subnet_t subnet) {
  88         if(((subnet.type == SUBNET_IPV4)
  89                         && !maskcheck(&subnet.net.ipv4.address, subnet.net.ipv4.prefixlength, sizeof(subnet.net.ipv4.address)))
  90                         || ((subnet.type == SUBNET_IPV6)
  91                             && !maskcheck(&subnet.net.ipv6.address, subnet.net.ipv6.prefixlength, sizeof(subnet.net.ipv6.address)))) {
  92                 return false;
  93         }
  94
  95         return true;
  96 }
  97
  98 bool maskcheck(const void *va, int masklen, int len) {
  99         int i;
 100         const char *a = va;
 101
 102         i = masklen / 8;
 103         masklen %= 8;
 104
 105         if(masklen && a[i++] & (0xff >> masklen)) {
 106                 return false;
 107         }
 108
 109         for(; i < len; i++)
 110                 if(a[i] != 0) {
 111                         return false;
 112                 }
 113
 114         return true;
 115 }
 116
 117 /* Subnet comparison */
 118
 119 static int subnet_compare_mac(const subnet_t *a, const subnet_t *b) {
 120         int result;
 121
 122         result = memcmp(&a->net.mac.address, &b->net.mac.address, sizeof(a->net.mac.address));
 123
 124         if(result) {
 125                 return result;
 126         }
 127
 128         result = a->weight - b->weight;
 129
 130         if(result || !a->owner || !b->owner) {
 131                 return result;
 132         }
 133
 134         return strcmp(a->owner->name, b->owner->name);
 135 }
 136
 137 static int subnet_compare_ipv4(const subnet_t *a, const subnet_t *b) {
 138         int result;
 139
 140         result = b->net.ipv4.prefixlength - a->net.ipv4.prefixlength;
 141
 142         if(result) {
 143                 return result;
 144         }
 145
 146         result = memcmp(&a->net.ipv4.address, &b->net.ipv4.address, sizeof(ipv4_t));
 147
 148         if(result) {
 149                 return result;
 150         }
 151
 152         result = a->weight - b->weight;
 153
 154         if(result || !a->owner || !b->owner) {
 155                 return result;
 156         }
 157
 158         return strcmp(a->owner->name, b->owner->name);
 159 }
 160
 161 static int subnet_compare_ipv6(const subnet_t *a, const subnet_t *b) {
 162         int result;
 163
 164         result = b->net.ipv6.prefixlength - a->net.ipv6.prefixlength;
 165
 166         if(result) {
 167                 return result;
 168         }
 169
 170         result = memcmp(&a->net.ipv6.address, &b->net.ipv6.address, sizeof(ipv6_t));
 171
 172         if(result) {
 173                 return result;
 174         }
 175
 176         result = a->weight - b->weight;
 177
 178         if(result || !a->owner || !b->owner) {
 179                 return result;
 180         }
 181
 182         return strcmp(a->owner->name, b->owner->name);
 183 }
 184
 185 int subnet_compare(const subnet_t *a, const subnet_t *b) {
 186         int result = (int)a->type - (int)b->type;
 187
 188         if(result) {
 189                 return result;
 190         }
 191
 192         switch(a->type) {
 193         case SUBNET_MAC:
 194                 return subnet_compare_mac(a, b);
 195
 196         case SUBNET_IPV4:
 197                 return subnet_compare_ipv4(a, b);
 198
 199         case SUBNET_IPV6:
 200                 return subnet_compare_ipv6(a, b);
 201
 202         default:
 203                 logger(DEBUG_ALWAYS, LOG_ERR, "subnet_compare() was called with unknown subnet type %d, exitting!", a->type);
 204                 exit(1);
 205         }
 206
 207         return 0;
 208 }
 209
 210 /* Ascii representation of subnets */
 211
 212 bool str2net(subnet_t *subnet, const char *subnetstr) {
 213         char str[64];
 214         strncpy(str, subnetstr, sizeof(str));
 215         str[sizeof(str) - 1] = 0;
 216         int consumed;
 217
 218         int weight = DEFAULT_WEIGHT;
 219         char *weight_separator = strchr(str, '#');
 220
 221         if(weight_separator) {
 222                 char *weight_str = weight_separator + 1;
 223
 224                 if(sscanf(weight_str, "%d%n", &weight, &consumed) < 1) {
 225                         return false;
 226                 }
 227
 228                 if(weight_str[consumed]) {
 229                         return false;
 230                 }
 231
 232                 *weight_separator = 0;
 233         }
 234
 235         int prefixlength = -1;
 236         char *prefixlength_separator = strchr(str, '/');
 237
 238         if(prefixlength_separator) {
 239                 char *prefixlength_str = prefixlength_separator + 1;
 240
 241                 if(sscanf(prefixlength_str, "%d%n", &prefixlength, &consumed) < 1) {
 242                         return false;
 243                 }
 244
 245                 if(prefixlength_str[consumed]) {
 246                         return false;
 247                 }
 248
 249                 *prefixlength_separator = 0;
 250
 251                 if(prefixlength < 0) {
 252                         return false;
 253                 }
 254         }
 255
 256         uint16_t x[8];
 257
 258         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]) {
 259                 /*
 260                    Normally we should check that each part has two digits to prevent ambiguities.
 261                    However, in old tinc versions net2str() will aggressively return MAC addresses with one-digit parts,
 262                    so we have to accept them otherwise we would be unable to parse ADD_SUBNET messages.
 263                 */
 264                 if(prefixlength >= 0) {
 265                         return false;
 266                 }
 267
 268                 subnet->type = SUBNET_MAC;
 269                 subnet->weight = weight;
 270
 271                 for(int i = 0; i < 6; i++) {
 272                         subnet->net.mac.address.x[i] = x[i];
 273                 }
 274
 275                 return true;
 276         }
 277
 278         if(inet_pton(AF_INET, str, &subnet->net.ipv4.address)) {
 279                 if(prefixlength == -1) {
 280                         prefixlength = 32;
 281                 }
 282
 283                 if(prefixlength > 32) {
 284                         return false;
 285                 }
 286
 287                 subnet->type = SUBNET_IPV4;
 288                 subnet->net.ipv4.prefixlength = prefixlength;
 289                 subnet->weight = weight;
 290
 291                 return true;
 292         }
 293
 294         if(inet_pton(AF_INET6, str, &subnet->net.ipv6.address)) {
 295                 if(prefixlength == -1) {
 296                         prefixlength = 128;
 297                 }
 298
 299                 if(prefixlength > 128) {
 300                         return false;
 301                 }
 302
 303                 subnet->type = SUBNET_IPV6;
 304                 subnet->net.ipv6.prefixlength = prefixlength;
 305                 subnet->weight = weight;
 306
 307                 return true;
 308         }
 309
 310         return false;
 311 }
 312
 313 bool net2str(char *netstr, int len, const subnet_t *subnet) {
 314         if(!netstr || !subnet) {
 315                 logger(DEBUG_ALWAYS, LOG_ERR, "net2str() was called with netstr=%p, subnet=%p!", (void *)netstr, (void *)subnet);
 316                 return false;
 317         }
 318
 319         int result;
 320         int prefixlength = -1;
 321
 322         switch(subnet->type) {
 323         case SUBNET_MAC:
 324                 snprintf(netstr, len, "%02x:%02x:%02x:%02x:%02x:%02x",
 325                          subnet->net.mac.address.x[0],
 326                          subnet->net.mac.address.x[1],
 327                          subnet->net.mac.address.x[2],
 328                          subnet->net.mac.address.x[3],
 329                          subnet->net.mac.address.x[4],
 330                          subnet->net.mac.address.x[5]);
 331                 break;
 332
 333         case SUBNET_IPV4:
 334                 inet_ntop(AF_INET, &subnet->net.ipv4.address, netstr, len);
 335                 prefixlength = subnet->net.ipv4.prefixlength;
 336
 337                 if(prefixlength == 32) {
 338                         prefixlength = -1;
 339                 }
 340
 341                 break;
 342
 343         case SUBNET_IPV6: {
 344                 inet_ntop(AF_INET6, &subnet->net.ipv6.address, netstr, len);
 345                 prefixlength = subnet->net.ipv6.prefixlength;
 346
 347                 if(prefixlength == 128) {
 348                         prefixlength = -1;
 349                 }
 350
 351                 break;
 352         }
 353
 354         default:
 355                 logger(DEBUG_ALWAYS, LOG_ERR, "net2str() was called with unknown subnet type %d, exiting!", subnet->type);
 356                 exit(1);
 357         }
 358
 359         size_t used = strlen(netstr);
 360         netstr += used;
 361         len -= used;
 362
 363         if(prefixlength >= 0) {
 364                 result = snprintf(netstr, len, "/%d", prefixlength);
 365                 netstr += result;
 366                 len -= result;
 367         }
 368
 369         if(subnet->weight != DEFAULT_WEIGHT) {
 370                 snprintf(netstr, len, "#%d", subnet->weight);
 371         }
 372
 373         return true;
 374 }