src/cadet/gnunet-service-cadet_dht.c

   1 /*
   2      This file is part of GNUnet.
   3      Copyright (C) 2013, 2017 GNUnet e.V.
   4
   5      GNUnet is free software: you can redistribute it and/or modify it
   6      under the terms of the GNU Affero General Public License as published
   7      by the Free Software Foundation, either version 3 of the License,
   8      or (at your option) any later version.
   9
  10      GNUnet is distributed in the hope that it will be useful, but
  11      WITHOUT ANY WARRANTY; without even the implied warranty of
  12      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13      Affero General Public License for more details.
  14
  15      You should have received a copy of the GNU Affero General Public License
  16      along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17
  18      SPDX-License-Identifier: AGPL3.0-or-later
  19 */
  20 /**
  21  * @file cadet/gnunet-service-cadet_dht.c
  22  * @brief Information we track per peer.
  23  * @author Bartlomiej Polot
  24  * @author Christian Grothoff
  25  */
  26
  27 #include "platform.h"
  28 #include "gnunet_util_lib.h"
  29 #include "gnunet_dht_service.h"
  30 #include "gnunet_statistics_service.h"
  31 #include "gnunet-service-cadet.h"
  32 #include "gnunet-service-cadet_dht.h"
  33 #include "gnunet-service-cadet_hello.h"
  34 #include "gnunet-service-cadet_peer.h"
  35 #include "gnunet-service-cadet_paths.h"
  36
  37 /**
  38  * How long do we wait before first announcing our presence to the DHT.
  39  * Used to wait for our HELLO to be available.  Note that we also get
  40  * notifications when our HELLO is ready, so this is just the maximum
  41  * we wait for the first notification.
  42  */
  43 #define STARTUP_DELAY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS, 500)
  44
  45 /**
  46  * How long do we wait after we get an updated HELLO before publishing?
  47  * Allows for the HELLO to be updated again quickly, for example in
  48  * case multiple addresses changed and we got a partial update.
  49  */
  50 #define CHANGE_DELAY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS, 100)
  51
  52
  53 #define LOG(level, ...) GNUNET_log_from (level,"cadet-dht",__VA_ARGS__)
  54
  55
  56 /**
  57  * Handle for DHT searches.
  58  */
  59 struct GCD_search_handle
  60 {
  61   /**
  62    * DHT_GET handle.
  63    */
  64   struct GNUNET_DHT_GetHandle *dhtget;
  65
  66 };
  67
  68
  69 /**
  70  * Handle to use DHT.
  71  */
  72 static struct GNUNET_DHT_Handle *dht_handle;
  73
  74 /**
  75  * How often to PUT own ID in the DHT.
  76  */
  77 static struct GNUNET_TIME_Relative id_announce_time;
  78
  79 /**
  80  * DHT replication level, see DHT API: #GNUNET_DHT_get_start(), #GNUNET_DHT_put().
  81  */
  82 static unsigned long long dht_replication_level;
  83
  84 /**
  85  * Task to periodically announce itself in the network.
  86  */
  87 static struct GNUNET_SCHEDULER_Task *announce_id_task;
  88
  89 /**
  90  * Delay for the next ID announce.
  91  */
  92 static struct GNUNET_TIME_Relative announce_delay;
  93
  94
  95 /**
  96  * Function to process paths received for a new peer addition. The recorded
  97  * paths form the initial tunnel, which can be optimized later.
  98  * Called on each result obtained for the DHT search.
  99  *
 100  * @param cls closure
 101  * @param exp when will this value expire
 102  * @param key key of the result
 103  * @param get_path path of the get request
 104  * @param get_path_length lenght of @a get_path
 105  * @param put_path path of the put request
 106  * @param put_path_length length of the @a put_path
 107  * @param type type of the result
 108  * @param size number of bytes in data
 109  * @param data pointer to the result data
 110  */
 111 static void
 112 dht_get_id_handler (void *cls, struct GNUNET_TIME_Absolute exp,
 113                     const struct GNUNET_HashCode *key,
 114                     const struct GNUNET_PeerIdentity *get_path,
 115                     unsigned int get_path_length,
 116                     const struct GNUNET_PeerIdentity *put_path,
 117                     unsigned int put_path_length,
 118                     enum GNUNET_BLOCK_Type type,
 119                     size_t size,
 120                     const void *data)
 121 {
 122   const struct GNUNET_HELLO_Message *hello = data;
 123   struct CadetPeer *peer;
 124
 125   GCPP_try_path_from_dht (get_path,
 126                           get_path_length,
 127                           put_path,
 128                           put_path_length);
 129   if ( (size >= sizeof (struct GNUNET_HELLO_Message)) &&
 130        (ntohs (hello->header.size) == size) &&
 131        (size == GNUNET_HELLO_size (hello)) )
 132   {
 133     peer = GCP_get (&put_path[0],
 134                     GNUNET_YES);
 135     LOG (GNUNET_ERROR_TYPE_DEBUG,
 136          "Got HELLO for %s\n",
 137          GCP_2s (peer));
 138     GCP_set_hello (peer,
 139                    hello);
 140   }
 141 }
 142
 143
 144 /**
 145  * Periodically announce self id in the DHT
 146  *
 147  * @param cls closure
 148  */
 149 static void
 150 announce_id (void *cls)
 151 {
 152   struct GNUNET_HashCode phash;
 153   const struct GNUNET_HELLO_Message *hello;
 154   size_t size;
 155   struct GNUNET_TIME_Absolute expiration;
 156   struct GNUNET_TIME_Relative next_put;
 157
 158   hello = GCH_get_mine ();
 159   size = (NULL != hello) ? GNUNET_HELLO_size (hello) : 0;
 160   if (0 == size)
 161   {
 162     expiration = GNUNET_TIME_absolute_add (GNUNET_TIME_absolute_get (),
 163                                            announce_delay);
 164     announce_delay = GNUNET_TIME_STD_BACKOFF (announce_delay);
 165   }
 166   else
 167   {
 168     expiration = GNUNET_HELLO_get_last_expiration (hello);
 169     announce_delay = GNUNET_TIME_UNIT_SECONDS;
 170   }
 171
 172   /* Call again in id_announce_time, unless HELLO expires first,
 173    * but wait at least 1s. */
 174   next_put
 175     = GNUNET_TIME_absolute_get_remaining (expiration);
 176   next_put
 177     = GNUNET_TIME_relative_min (next_put,
 178                                 id_announce_time);
 179   next_put
 180     = GNUNET_TIME_relative_max (next_put,
 181                                 GNUNET_TIME_UNIT_SECONDS);
 182   announce_id_task
 183     = GNUNET_SCHEDULER_add_delayed (next_put,
 184                                     &announce_id,
 185                                     cls);
 186   GNUNET_STATISTICS_update (stats,
 187                             "# DHT announce",
 188                             1,
 189                             GNUNET_NO);
 190   memset (&phash,
 191           0,
 192           sizeof (phash));
 193   GNUNET_memcpy (&phash,
 194                  &my_full_id,
 195                  sizeof (my_full_id));
 196   LOG (GNUNET_ERROR_TYPE_DEBUG,
 197        "Announcing my HELLO (%u bytes) in the DHT\n",
 198        size);
 199   GNUNET_DHT_put (dht_handle,   /* DHT handle */
 200                   &phash,       /* Key to use */
 201                   dht_replication_level,     /* Replication level */
 202                   GNUNET_DHT_RO_RECORD_ROUTE
 203                   | GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE,    /* DHT options */
 204                   GNUNET_BLOCK_TYPE_DHT_HELLO,       /* Block type */
 205                   size,  /* Size of the data */
 206                   (const char *) hello, /* Data itself */
 207                   expiration,  /* Data expiration */
 208                   NULL,         /* Continuation */
 209                   NULL);        /* Continuation closure */
 210 }
 211
 212
 213 /**
 214  * Function called by the HELLO subsystem whenever OUR hello
 215  * changes. Re-triggers the DHT PUT immediately.
 216  */
 217 void
 218 GCD_hello_update ()
 219 {
 220   if (NULL == announce_id_task)
 221     return; /* too early */
 222   GNUNET_SCHEDULER_cancel (announce_id_task);
 223   announce_id_task
 224     = GNUNET_SCHEDULER_add_delayed (CHANGE_DELAY,
 225                                     &announce_id,
 226                                     NULL);
 227 }
 228
 229
 230 /**
 231  * Initialize the DHT subsystem.
 232  *
 233  * @param c Configuration.
 234  */
 235 void
 236 GCD_init (const struct GNUNET_CONFIGURATION_Handle *c)
 237 {
 238   if (GNUNET_OK !=
 239       GNUNET_CONFIGURATION_get_value_number (c,
 240                                              "CADET",
 241                                              "DHT_REPLICATION_LEVEL",
 242                                              &dht_replication_level))
 243   {
 244     GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_WARNING,
 245                                "CADET",
 246                                "DHT_REPLICATION_LEVEL",
 247                                "USING DEFAULT");
 248     dht_replication_level = 3;
 249   }
 250
 251   if (GNUNET_OK !=
 252       GNUNET_CONFIGURATION_get_value_time (c,
 253                                            "CADET",
 254                                            "ID_ANNOUNCE_TIME",
 255                                            &id_announce_time))
 256   {
 257     GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_ERROR,
 258                                "CADET",
 259                                "ID_ANNOUNCE_TIME",
 260                                "MISSING");
 261     GNUNET_SCHEDULER_shutdown ();
 262     return;
 263   }
 264
 265   dht_handle = GNUNET_DHT_connect (c,
 266                                    64);
 267   GNUNET_break (NULL != dht_handle);
 268   announce_delay = GNUNET_TIME_UNIT_SECONDS;
 269   announce_id_task = GNUNET_SCHEDULER_add_delayed (STARTUP_DELAY,
 270                                                    &announce_id,
 271                                                    NULL);
 272 }
 273
 274
 275 /**
 276  * Shut down the DHT subsystem.
 277  */
 278 void
 279 GCD_shutdown (void)
 280 {
 281   if (NULL != dht_handle)
 282   {
 283     GNUNET_DHT_disconnect (dht_handle);
 284     dht_handle = NULL;
 285   }
 286   if (NULL != announce_id_task)
 287   {
 288     GNUNET_SCHEDULER_cancel (announce_id_task);
 289     announce_id_task = NULL;
 290   }
 291 }
 292
 293
 294 /**
 295  * Search DHT for paths to @a peeR_id
 296  *
 297  * @param peer_id peer to search for
 298  * @return handle to abort search
 299  */
 300 struct GCD_search_handle *
 301 GCD_search (const struct GNUNET_PeerIdentity *peer_id)
 302 {
 303   struct GNUNET_HashCode phash;
 304   struct GCD_search_handle *h;
 305
 306   GNUNET_STATISTICS_update (stats,
 307                             "# DHT search",
 308                             1,
 309                             GNUNET_NO);
 310   memset (&phash,
 311           0,
 312           sizeof (phash));
 313   GNUNET_memcpy (&phash,
 314                  peer_id,
 315                  sizeof (*peer_id));
 316
 317   h = GNUNET_new (struct GCD_search_handle);
 318   h->dhtget = GNUNET_DHT_get_start (dht_handle,    /* handle */
 319                                     GNUNET_BLOCK_TYPE_DHT_HELLO, /* type */
 320                                     &phash,     /* key to search */
 321                                     dht_replication_level, /* replication level */
 322                                     GNUNET_DHT_RO_RECORD_ROUTE |
 323                                     GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE,
 324                                     NULL,       /* xquery */
 325                                     0,     /* xquery bits */
 326                                     &dht_get_id_handler,
 327                                     h);
 328   LOG (GNUNET_ERROR_TYPE_DEBUG,
 329        "Starting DHT GET for peer %s (%p)\n",
 330        GNUNET_i2s (peer_id),
 331        h);
 332   return h;
 333 }
 334
 335
 336 /**
 337  * Stop DHT search started with #GCD_search().
 338  *
 339  * @param h handle to search to stop
 340  */
 341 void
 342 GCD_search_stop (struct GCD_search_handle *h)
 343 {
 344   LOG (GNUNET_ERROR_TYPE_DEBUG,
 345        "Stopping DHT GET %p\n",
 346        h);
 347   GNUNET_DHT_get_stop (h->dhtget);
 348   GNUNET_free (h);
 349 }
 350
 351 /* end of gnunet-service-cadet_dht.c */