src/revocation/plugin_block_revocation.c

   1 /*
   2      This file is part of GNUnet
   3      Copyright (C) 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 /**
  22  * @file block/plugin_block_revocation.c
  23  * @brief revocation for a block plugin
  24  * @author Christian Grothoff
  25  */
  26
  27 #include "platform.h"
  28 #include "gnunet_signatures.h"
  29 #include "gnunet_block_plugin.h"
  30 #include "gnunet_block_group_lib.h"
  31 #include "revocation.h"
  32 #include "gnunet_revocation_service.h"
  33
  34 #define DEBUG_REVOCATION GNUNET_EXTRA_LOGGING
  35
  36 /**
  37  * Number of bits we set per entry in the bloomfilter.
  38  * Do not change!
  39  */
  40 #define BLOOMFILTER_K 16
  41
  42
  43 /**
  44  * How big is the BF we use for DHT blocks?
  45  */
  46 #define REVOCATION_BF_SIZE 8
  47
  48
  49 /**
  50  * Context used inside the plugin.
  51  */
  52 struct InternalContext
  53 {
  54   unsigned int matching_bits;
  55   struct GNUNET_TIME_Relative epoch_duration;
  56 };
  57
  58
  59 /**
  60  * Create a new block group.
  61  *
  62  * @param ctx block context in which the block group is created
  63  * @param type type of the block for which we are creating the group
  64  * @param nonce random value used to seed the group creation
  65  * @param raw_data optional serialized prior state of the group, NULL if unavailable/fresh
  66  * @param raw_data_size number of bytes in @a raw_data, 0 if unavailable/fresh
  67  * @param va variable arguments specific to @a type
  68  * @return block group handle, NULL if block groups are not supported
  69  *         by this @a type of block (this is not an error)
  70  */
  71 static struct GNUNET_BLOCK_Group *
  72 block_plugin_revocation_create_group (void *cls,
  73                                       enum GNUNET_BLOCK_Type type,
  74                                       uint32_t nonce,
  75                                       const void *raw_data,
  76                                       size_t raw_data_size,
  77                                       va_list va)
  78 {
  79   unsigned int bf_size;
  80   const char *guard;
  81
  82   guard = va_arg (va, const char *);
  83   if (0 == strcmp (guard,
  84                    "seen-set-size"))
  85     bf_size = GNUNET_BLOCK_GROUP_compute_bloomfilter_size (va_arg (va, unsigned
  86                                                                    int),
  87                                                            BLOOMFILTER_K);
  88   else if (0 == strcmp (guard,
  89                         "filter-size"))
  90     bf_size = va_arg (va, unsigned int);
  91   else
  92   {
  93     GNUNET_break (0);
  94     bf_size = REVOCATION_BF_SIZE;
  95   }
  96   GNUNET_break (NULL == va_arg (va, const char *));
  97   return GNUNET_BLOCK_GROUP_bf_create (cls,
  98                                        bf_size,
  99                                        BLOOMFILTER_K,
 100                                        type,
 101                                        nonce,
 102                                        raw_data,
 103                                        raw_data_size);
 104 }
 105
 106
 107 /**
 108  * Function called to validate a reply or a request.  For
 109  * request evaluation, simply pass "NULL" for the reply_block.
 110  *
 111  * @param cls our `struct InternalContext`
 112  * @param ctx context
 113  * @param type block type
 114  * @param group block group to use
 115  * @param eo control flags
 116  * @param query original query (hash)
 117  * @param xquery extrended query data (can be NULL, depending on type)
 118  * @param xquery_size number of bytes in xquery
 119  * @param reply_block response to validate
 120  * @param reply_block_size number of bytes in reply block
 121  * @return characterization of result
 122  */
 123 static enum GNUNET_BLOCK_EvaluationResult
 124 block_plugin_revocation_evaluate (void *cls,
 125                                   struct GNUNET_BLOCK_Context *ctx,
 126                                   enum GNUNET_BLOCK_Type type,
 127                                   struct GNUNET_BLOCK_Group *group,
 128                                   enum GNUNET_BLOCK_EvaluationOptions eo,
 129                                   const struct GNUNET_HashCode *query,
 130                                   const void *xquery,
 131                                   size_t xquery_size,
 132                                   const void *reply_block,
 133                                   size_t reply_block_size)
 134 {
 135   struct InternalContext *ic = cls;
 136   struct GNUNET_HashCode chash;
 137   const struct RevokeMessage *rm = reply_block;
 138
 139   if (NULL == reply_block)
 140     return GNUNET_BLOCK_EVALUATION_REQUEST_VALID;
 141   if (reply_block_size != sizeof(*rm))
 142   {
 143     GNUNET_break_op (0);
 144     return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
 145   }
 146   if (0 >=
 147       GNUNET_REVOCATION_check_pow (&rm->proof_of_work,
 148                                    ic->matching_bits,
 149                                    ic->epoch_duration))
 150   {
 151     GNUNET_break_op (0);
 152     return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
 153   }
 154   GNUNET_CRYPTO_hash (&rm->proof_of_work.key,
 155                       sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey),
 156                       &chash);
 157   if (GNUNET_YES ==
 158       GNUNET_BLOCK_GROUP_bf_test_and_set (group,
 159                                           &chash))
 160     return GNUNET_BLOCK_EVALUATION_OK_DUPLICATE;
 161   return GNUNET_BLOCK_EVALUATION_TYPE_NOT_SUPPORTED;
 162 }
 163
 164
 165 /**
 166  * Function called to obtain the key for a block.
 167  *
 168  * @param cls closure
 169  * @param type block type
 170  * @param block block to get the key for
 171  * @param block_size number of bytes in block
 172  * @param key set to the key (query) for the given block
 173  * @return #GNUNET_OK on success, #GNUNET_SYSERR if type not supported
 174  *         (or if extracting a key from a block of this type does not work)
 175  */
 176 static int
 177 block_plugin_revocation_get_key (void *cls,
 178                                  enum GNUNET_BLOCK_Type type,
 179                                  const void *block,
 180                                  size_t block_size,
 181                                  struct GNUNET_HashCode *key)
 182 {
 183   const struct RevokeMessage *rm = block;
 184
 185   if (block_size != sizeof(*rm))
 186   {
 187     GNUNET_break_op (0);
 188     return GNUNET_SYSERR;
 189   }
 190   GNUNET_CRYPTO_hash (&rm->proof_of_work.key,
 191                       sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey),
 192                       key);
 193   return GNUNET_OK;
 194 }
 195
 196
 197 /**
 198  * Entry point for the plugin.
 199  *
 200  * @param cls the configuration to use
 201  */
 202 void *
 203 libgnunet_plugin_block_revocation_init (void *cls)
 204 {
 205   static enum GNUNET_BLOCK_Type types[] = {
 206     GNUNET_BLOCK_TYPE_REVOCATION,
 207     GNUNET_BLOCK_TYPE_ANY       /* end of list */
 208   };
 209   const struct GNUNET_CONFIGURATION_Handle *cfg = cls;
 210   struct GNUNET_BLOCK_PluginFunctions *api;
 211   struct InternalContext *ic;
 212   unsigned long long matching_bits;
 213   struct GNUNET_TIME_Relative epoch_duration;
 214
 215   if (GNUNET_OK !=
 216       GNUNET_CONFIGURATION_get_value_number (cfg,
 217                                              "REVOCATION",
 218                                              "WORKBITS",
 219                                              &matching_bits))
 220     return NULL;
 221   if (GNUNET_OK !=
 222       GNUNET_CONFIGURATION_get_value_time (cfg,
 223                                            "REVOCATION",
 224                                            "EPOCH_DURATION",
 225                                            &epoch_duration))
 226     return NULL;
 227
 228   api = GNUNET_new (struct GNUNET_BLOCK_PluginFunctions);
 229   api->evaluate = &block_plugin_revocation_evaluate;
 230   api->get_key = &block_plugin_revocation_get_key;
 231   api->create_group = &block_plugin_revocation_create_group;
 232   api->types = types;
 233   ic = GNUNET_new (struct InternalContext);
 234   ic->matching_bits = (unsigned int) matching_bits;
 235   ic->epoch_duration = epoch_duration;
 236   api->cls = ic;
 237   return api;
 238 }
 239
 240
 241 /**
 242  * Exit point from the plugin.
 243  */
 244 void *
 245 libgnunet_plugin_block_revocation_done (void *cls)
 246 {
 247   struct GNUNET_BLOCK_PluginFunctions *api = cls;
 248   struct InternalContext *ic = api->cls;
 249
 250   GNUNET_free (ic);
 251   GNUNET_free (api);
 252   return NULL;
 253 }
 254
 255
 256 /* end of plugin_block_revocation.c */