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);
  71         }
  72 }
  73
  74 static unsigned int find_cached(address_cache_t *cache, const sockaddr_t *sa) {
  75         for(unsigned int i = 0; i < cache->data.used; i++)
  76                 if(!sockaddrcmp(&cache->data.address[i], sa)) {
  77                         return i;
  78                 }
  79
  80         return NOT_CACHED;
  81 }
  82
  83 void add_recent_address(address_cache_t *cache, const sockaddr_t *sa) {
  84         // Check if it's already cached
  85         unsigned int pos = find_cached(cache, sa);
  86
  87         // It's in the first spot, so nothing to do
  88         if(pos == 0) {
  89                 return;
  90         }
  91
  92         // Shift everything, move/add the address to the first slot
  93         if(pos == NOT_CACHED) {
  94                 if(cache->data.used < MAX_CACHED_ADDRESSES) {
  95                         cache->data.used++;
  96                 }
  97
  98                 pos = cache->data.used - 1;
  99         }
 100
 101         memmove(&cache->data.address[1], &cache->data.address[0], pos * sizeof(cache->data.address[0]));
 102
 103         cache->data.address[0] = *sa;
 104
 105         // Write the cache
 106         char fname[PATH_MAX];
 107         snprintf(fname, sizeof(fname), "%s" SLASH "cache" SLASH "%s", confbase, cache->node->name);
 108         FILE *fp = fopen(fname, "wb");
 109
 110         if(fp) {
 111                 fprintf(stderr, "Writing cache to %s\n", fname);
 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
 133                                 if(find_cached(cache, sa) != NOT_CACHED) {
 134                                         continue;
 135                                 }
 136
 137                                 cache->aip = cache->aip->ai_next;
 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                 init_configuration(&cache->config_tree);
 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->ai) {
 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                 cache->aip = cache->ai = str2addrinfo(address, port, SOCK_STREAM);
 172
 173                 if(cache->ai) {
 174                         struct addrinfo *ai = NULL;
 175
 176                         for(; cache->aip; cache->aip = cache->aip->ai_next) {
 177                                 struct addrinfo *oai = ai;
 178
 179                                 ai = xzalloc(sizeof(*ai));
 180                                 ai->ai_family = cache->aip->ai_family;
 181                                 ai->ai_socktype = cache->aip->ai_socktype;
 182                                 ai->ai_protocol = cache->aip->ai_protocol;
 183                                 ai->ai_addrlen = cache->aip->ai_addrlen;
 184                                 ai->ai_addr = xmalloc(ai->ai_addrlen);
 185                                 memcpy(ai->ai_addr, cache->aip->ai_addr, ai->ai_addrlen);
 186                                 ai->ai_next = oai;
 187                         }
 188
 189                         freeaddrinfo(cache->ai);
 190                         cache->aip = cache->ai = ai;
 191                 }
 192
 193                 free(address);
 194                 free(port);
 195
 196                 cache->cfg = lookup_config_next(cache->config_tree, cache->cfg);
 197         }
 198
 199         if(cache->ai) {
 200                 if(cache->aip) {
 201                         sockaddr_t *sa = (sockaddr_t *)cache->aip->ai_addr;
 202
 203                         cache->aip = cache->aip->ai_next;
 204                         return sa;
 205                 } else {
 206                         free_known_addresses(cache->ai);
 207                         cache->ai = NULL;
 208                 }
 209         }
 210
 211         // We're all out of addresses.
 212         exit_configuration(&cache->config_tree);
 213         return false;
 214 }
 215
 216 address_cache_t *open_address_cache(node_t *node) {
 217         address_cache_t *cache = xmalloc(sizeof(*cache));
 218         cache->node = node;
 219
 220         // Try to open an existing address cache
 221         char fname[PATH_MAX];
 222         snprintf(fname, sizeof(fname), "%s" SLASH "cache" SLASH "%s", confbase, node->name);
 223         FILE *fp = fopen(fname, "rb");
 224
 225         if(!fp || fread(&cache->data, sizeof(cache->data), 1, fp) != 1 || cache->data.version != ADDRESS_CACHE_VERSION) {
 226                 memset(&cache->data, 0, sizeof(cache->data));
 227         }
 228
 229         if(fp) {
 230                 fclose(fp);
 231         }
 232
 233         // Ensure we have a valid state
 234         cache->config_tree = NULL;
 235         cache->cfg = NULL;
 236         cache->ai = NULL;
 237         cache->aip = NULL;
 238         cache->tried = 0;
 239         cache->data.version = ADDRESS_CACHE_VERSION;
 240
 241         if(cache->data.used > MAX_CACHED_ADDRESSES) {
 242                 cache->data.used = 0;
 243         }
 244
 245         return cache;
 246 }
 247
 248 void reset_address_cache(address_cache_t *cache, const sockaddr_t *sa) {
 249         if(sa) {
 250                 add_recent_address(cache, sa);
 251         }
 252
 253         if(cache->config_tree) {
 254                 exit_configuration(&cache->config_tree);
 255         }
 256
 257         if(cache->ai) {
 258                 free_known_addresses(cache->ai);
 259         }
 260
 261         cache->config_tree = NULL;
 262         cache->cfg = NULL;
 263         cache->ai = NULL;
 264         cache->aip = NULL;
 265         cache->tried = 0;
 266 }
 267
 268 void close_address_cache(address_cache_t *cache) {
 269         if(cache->config_tree) {
 270                 exit_configuration(&cache->config_tree);
 271         }
 272
 273         if(cache->ai) {
 274                 free_known_addresses(cache->ai);
 275         }
 276
 277         free(cache);
 278 }