git.tinc-vpn.org Git - tinc/blob - src/address_cache.c

   1 /*
   2     address_cache.c -- Manage cache of recently seen addresses
   3     Copyright (C) 2018 Guus Sliepen <guus@tinc-vpn.org>
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License along
  16     with this program; if not, write to the Free Software Foundation, Inc.,
  17     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #include "system.h"
  21
  22 #include "address_cache.h"
  23 #include "conf.h"
  24 #include "names.h"
  25 #include "netutl.h"
  26 #include "xalloc.h"
  27
  28 static const unsigned int NOT_CACHED = -1;
  29
  30 // Find edges pointing to this node, and use them to build a list of unique, known addresses.
  31 static struct addrinfo *get_known_addresses(node_t *n) {
  32         struct addrinfo *ai = NULL;
  33         struct addrinfo *oai = NULL;
  34
  35         for splay_each(edge_t, e, &n->edge_tree) {
  36                 if(!e->reverse) {
  37                         continue;
  38                 }
  39
  40                 bool found = false;
  41
  42                 for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
  43                         if(!sockaddrcmp(&e->reverse->address, (sockaddr_t *)aip->ai_addr)) {
  44                                 found = true;
  45                                 break;
  46                         }
  47                 }
  48
  49                 if(found) {
  50                         continue;
  51                 }
  52
  53                 oai = ai;
  54                 ai = xzalloc(sizeof(*ai));
  55                 ai->ai_family = e->reverse->address.sa.sa_family;
  56                 ai->ai_socktype = SOCK_STREAM;
  57                 ai->ai_protocol = IPPROTO_TCP;
  58                 ai->ai_addrlen = SALEN(e->reverse->address.sa);
  59                 ai->ai_addr = xmalloc(ai->ai_addrlen);
  60                 memcpy(ai->ai_addr, &e->reverse->address, ai->ai_addrlen);
  61                 ai->ai_next = oai;
  62         }
  63
  64         return ai;
  65 }
  66
  67 static void free_known_addresses(struct addrinfo *ai) {
  68         for(struct addrinfo *aip = ai, *next; aip; aip = next) {
  69                 next = aip->ai_next;
  70                 free(aip->ai_addr);
  71                 free(aip);
  72         }
  73 }
  74
  75 static unsigned int find_cached(address_cache_t *cache, const sockaddr_t *sa) {
  76         for(unsigned int i = 0; i < cache->data.used; i++)
  77                 if(!sockaddrcmp(&cache->data.address[i], sa)) {
  78                         return i;
  79                 }
  80
  81         return NOT_CACHED;
  82 }
  83
  84 void add_recent_address(address_cache_t *cache, const sockaddr_t *sa) {
  85         // Check if it's already cached
  86         unsigned int pos = find_cached(cache, sa);
  87
  88         // It's in the first spot, so nothing to do
  89         if(pos == 0) {
  90                 return;
  91         }
  92
  93         // Shift everything, move/add the address to the first slot
  94         if(pos == NOT_CACHED) {
  95                 if(cache->data.used < MAX_CACHED_ADDRESSES) {
  96                         cache->data.used++;
  97                 }
  98
  99                 pos = cache->data.used - 1;
 100         }
 101
 102         memmove(&cache->data.address[1], &cache->data.address[0], pos * sizeof(cache->data.address[0]));
 103
 104         cache->data.address[0] = *sa;
 105
 106         // Write the cache
 107         char fname[PATH_MAX];
 108         snprintf(fname, sizeof(fname), "%s" SLASH "cache" SLASH "%s", confbase, cache->node->name);
 109         FILE *fp = fopen(fname, "wb");
 110
 111         if(fp) {
 112                 fwrite(&cache->data, sizeof(cache->data), 1, fp);
 113                 fclose(fp);
 114         }
 115 }
 116
 117 const sockaddr_t *get_recent_address(address_cache_t *cache) {
 118         // Check if there is an address in our cache of recently seen addresses
 119         if(cache->tried < cache->data.used) {
 120                 return &cache->data.address[cache->tried++];
 121         }
 122
 123         // Next, check any recently seen addresses not in our cache
 124         while(cache->tried == cache->data.used) {
 125                 if(!cache->ai) {
 126                         cache->aip = cache->ai = get_known_addresses(cache->node);
 127                 }
 128
 129                 if(cache->ai) {
 130                         if(cache->aip) {
 131                                 sockaddr_t *sa = (sockaddr_t *)cache->aip->ai_addr;
 132                                 cache->aip = cache->aip->ai_next;
 133
 134                                 if(find_cached(cache, sa) != NOT_CACHED) {
 135                                         continue;
 136                                 }
 137
 138                                 return sa;
 139                         } else {
 140                                 free_known_addresses(cache->ai);
 141                                 cache->ai = NULL;
 142                         }
 143                 }
 144
 145                 cache->tried++;
 146         }
 147
 148         // Otherwise, check if there are any known Address statements
 149         if(!cache->config_tree) {
 150                 cache->config_tree = create_configuration();
 151                 read_host_config(cache->config_tree, cache->node->name, false);
 152                 cache->cfg = lookup_config(cache->config_tree, "Address");
 153         }
 154
 155         while(cache->cfg && !cache->aip) {
 156                 char *address, *port;
 157
 158                 get_config_string(cache->cfg, &address);
 159
 160                 char *space = strchr(address, ' ');
 161
 162                 if(space) {
 163                         port = xstrdup(space + 1);
 164                         *space = 0;
 165                 } else {
 166                         if(!get_config_string(lookup_config(cache->config_tree, "Port"), &port)) {
 167                                 port = xstrdup("655");
 168                         }
 169                 }
 170
 171                 if(cache->ai) {
 172                         free_known_addresses(cache->ai);
 173                 }
 174
 175                 cache->aip = cache->ai = str2addrinfo(address, port, SOCK_STREAM);
 176
 177                 if(cache->ai) {
 178                         struct addrinfo *ai = NULL;
 179
 180                         for(; cache->aip; cache->aip = cache->aip->ai_next) {
 181                                 struct addrinfo *oai = ai;
 182
 183                                 ai = xzalloc(sizeof(*ai));
 184                                 ai->ai_family = cache->aip->ai_family;
 185                                 ai->ai_socktype = cache->aip->ai_socktype;
 186                                 ai->ai_protocol = cache->aip->ai_protocol;
 187                                 ai->ai_addrlen = cache->aip->ai_addrlen;
 188                                 ai->ai_addr = xmalloc(ai->ai_addrlen);
 189                                 memcpy(ai->ai_addr, cache->aip->ai_addr, ai->ai_addrlen);
 190                                 ai->ai_next = oai;
 191                         }
 192
 193                         freeaddrinfo(cache->ai);
 194                         cache->aip = cache->ai = ai;
 195                 }
 196
 197                 free(address);
 198                 free(port);
 199
 200                 cache->cfg = lookup_config_next(cache->config_tree, cache->cfg);
 201         }
 202
 203         if(cache->ai) {
 204                 if(cache->aip) {
 205                         sockaddr_t *sa = (sockaddr_t *)cache->aip->ai_addr;
 206
 207                         cache->aip = cache->aip->ai_next;
 208                         return sa;
 209                 } else {
 210                         free_known_addresses(cache->ai);
 211                         cache->ai = NULL;
 212                 }
 213         }
 214
 215         // We're all out of addresses.
 216         exit_configuration(&cache->config_tree);
 217         return false;
 218 }
 219
 220 address_cache_t *open_address_cache(node_t *node) {
 221         address_cache_t *cache = xmalloc(sizeof(*cache));
 222         cache->node = node;
 223
 224         // Try to open an existing address cache
 225         char fname[PATH_MAX];
 226         snprintf(fname, sizeof(fname), "%s" SLASH "cache" SLASH "%s", confbase, node->name);
 227         FILE *fp = fopen(fname, "rb");
 228
 229         if(!fp || fread(&cache->data, sizeof(cache->data), 1, fp) != 1 || cache->data.version != ADDRESS_CACHE_VERSION) {
 230                 memset(&cache->data, 0, sizeof(cache->data));
 231         }
 232
 233         if(fp) {
 234                 fclose(fp);
 235         }
 236
 237         // Ensure we have a valid state
 238         cache->config_tree = NULL;
 239         cache->cfg = NULL;
 240         cache->ai = NULL;
 241         cache->aip = NULL;
 242         cache->tried = 0;
 243         cache->data.version = ADDRESS_CACHE_VERSION;
 244
 245         if(cache->data.used > MAX_CACHED_ADDRESSES) {
 246                 cache->data.used = 0;
 247         }
 248
 249         return cache;
 250 }
 251
 252 void reset_address_cache(address_cache_t *cache, const sockaddr_t *sa) {
 253         if(sa) {
 254                 add_recent_address(cache, sa);
 255         }
 256
 257         if(cache->config_tree) {
 258                 exit_configuration(&cache->config_tree);
 259         }
 260
 261         if(cache->ai) {
 262                 free_known_addresses(cache->ai);
 263         }
 264
 265         cache->config_tree = NULL;
 266         cache->cfg = NULL;
 267         cache->ai = NULL;
 268         cache->aip = NULL;
 269         cache->tried = 0;
 270 }
 271
 272 void close_address_cache(address_cache_t *cache) {
 273         if(cache->config_tree) {
 274                 exit_configuration(&cache->config_tree);
 275         }
 276
 277         if(cache->ai) {
 278                 free_known_addresses(cache->ai);
 279         }
 280
 281         free(cache);
 282 }