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   unsigned int matching_bits;
  54 };
  55
  56
  57 /**
  58  * Create a new block group.
  59  *
  60  * @param ctx block context in which the block group is created
  61  * @param type type of the block for which we are creating the group
  62  * @param nonce random value used to seed the group creation
  63  * @param raw_data optional serialized prior state of the group, NULL if unavailable/fresh
  64  * @param raw_data_size number of bytes in @a raw_data, 0 if unavailable/fresh
  65  * @param va variable arguments specific to @a type
  66  * @return block group handle, NULL if block groups are not supported
  67  *         by this @a type of block (this is not an error)
  68  */
  69 static struct GNUNET_BLOCK_Group *
  70 block_plugin_revocation_create_group(void *cls,
  71                                      enum GNUNET_BLOCK_Type type,
  72                                      uint32_t nonce,
  73                                      const void *raw_data,
  74                                      size_t raw_data_size,
  75                                      va_list va)
  76 {
  77   unsigned int bf_size;
  78   const char *guard;
  79
  80   guard = va_arg(va, const char *);
  81   if (0 == strcmp(guard,
  82                   "seen-set-size"))
  83     bf_size = GNUNET_BLOCK_GROUP_compute_bloomfilter_size(va_arg(va, unsigned int),
  84                                                           BLOOMFILTER_K);
  85   else if (0 == strcmp(guard,
  86                        "filter-size"))
  87     bf_size = va_arg(va, unsigned int);
  88   else
  89     {
  90       GNUNET_break(0);
  91       bf_size = REVOCATION_BF_SIZE;
  92     }
  93   GNUNET_break(NULL == va_arg(va, const char *));
  94   return GNUNET_BLOCK_GROUP_bf_create(cls,
  95                                       bf_size,
  96                                       BLOOMFILTER_K,
  97                                       type,
  98                                       nonce,
  99                                       raw_data,
 100                                       raw_data_size);
 101 }
 102
 103
 104 /**
 105  * Function called to validate a reply or a request.  For
 106  * request evaluation, simply pass "NULL" for the reply_block.
 107  *
 108  * @param cls our `struct InternalContext`
 109  * @param ctx context
 110  * @param type block type
 111  * @param group block group to use
 112  * @param eo control flags
 113  * @param query original query (hash)
 114  * @param xquery extrended query data (can be NULL, depending on type)
 115  * @param xquery_size number of bytes in xquery
 116  * @param reply_block response to validate
 117  * @param reply_block_size number of bytes in reply block
 118  * @return characterization of result
 119  */
 120 static enum GNUNET_BLOCK_EvaluationResult
 121 block_plugin_revocation_evaluate(void *cls,
 122                                  struct GNUNET_BLOCK_Context *ctx,
 123                                  enum GNUNET_BLOCK_Type type,
 124                                  struct GNUNET_BLOCK_Group *group,
 125                                  enum GNUNET_BLOCK_EvaluationOptions eo,
 126                                  const struct GNUNET_HashCode *query,
 127                                  const void *xquery,
 128                                  size_t xquery_size,
 129                                  const void *reply_block,
 130                                  size_t reply_block_size)
 131 {
 132   struct InternalContext *ic = cls;
 133   struct GNUNET_HashCode chash;
 134   const struct RevokeMessage *rm = reply_block;
 135
 136   if (NULL == reply_block)
 137     return GNUNET_BLOCK_EVALUATION_REQUEST_VALID;
 138   if (reply_block_size != sizeof(*rm))
 139     {
 140       GNUNET_break_op(0);
 141       return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
 142     }
 143   if (GNUNET_YES !=
 144       GNUNET_REVOCATION_check_pow(&rm->public_key,
 145                                   rm->proof_of_work,
 146                                   ic->matching_bits))
 147     {
 148       GNUNET_break_op(0);
 149       return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
 150     }
 151   if (GNUNET_OK !=
 152       GNUNET_CRYPTO_ecdsa_verify(GNUNET_SIGNATURE_PURPOSE_REVOCATION,
 153                                  &rm->purpose,
 154                                  &rm->signature,
 155                                  &rm->public_key))
 156     {
 157       GNUNET_break_op(0);
 158       return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
 159     }
 160   GNUNET_CRYPTO_hash(&rm->public_key,
 161                      sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey),
 162                      &chash);
 163   if (GNUNET_YES ==
 164       GNUNET_BLOCK_GROUP_bf_test_and_set(group,
 165                                          &chash))
 166     return GNUNET_BLOCK_EVALUATION_OK_DUPLICATE;
 167   return GNUNET_BLOCK_EVALUATION_TYPE_NOT_SUPPORTED;
 168 }
 169
 170
 171 /**
 172  * Function called to obtain the key for a block.
 173  *
 174  * @param cls closure
 175  * @param type block type
 176  * @param block block to get the key for
 177  * @param block_size number of bytes in block
 178  * @param key set to the key (query) for the given block
 179  * @return #GNUNET_OK on success, #GNUNET_SYSERR if type not supported
 180  *         (or if extracting a key from a block of this type does not work)
 181  */
 182 static int
 183 block_plugin_revocation_get_key(void *cls,
 184                                 enum GNUNET_BLOCK_Type type,
 185                                 const void *block,
 186                                 size_t block_size,
 187                                 struct GNUNET_HashCode *key)
 188 {
 189   const struct RevokeMessage *rm = block;
 190
 191   if (block_size != sizeof(*rm))
 192     {
 193       GNUNET_break_op(0);
 194       return GNUNET_SYSERR;
 195     }
 196   GNUNET_CRYPTO_hash(&rm->public_key,
 197                      sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey),
 198                      key);
 199   return GNUNET_OK;
 200 }
 201
 202
 203 /**
 204  * Entry point for the plugin.
 205  *
 206  * @param cls the configuration to use
 207  */
 208 void *
 209 libgnunet_plugin_block_revocation_init(void *cls)
 210 {
 211   static enum GNUNET_BLOCK_Type types[] =
 212   {
 213     GNUNET_BLOCK_TYPE_REVOCATION,
 214     GNUNET_BLOCK_TYPE_ANY       /* end of list */
 215   };
 216   const struct GNUNET_CONFIGURATION_Handle *cfg = cls;
 217   struct GNUNET_BLOCK_PluginFunctions *api;
 218   struct InternalContext *ic;
 219   unsigned long long matching_bits;
 220
 221   if (GNUNET_OK !=
 222       GNUNET_CONFIGURATION_get_value_number(cfg,
 223                                             "REVOCATION",
 224                                             "WORKBITS",
 225                                             &matching_bits))
 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   api->cls = ic;
 236   return api;
 237 }
 238
 239
 240 /**
 241  * Exit point from the plugin.
 242  */
 243 void *
 244 libgnunet_plugin_block_revocation_done(void *cls)
 245 {
 246   struct GNUNET_BLOCK_PluginFunctions *api = cls;
 247   struct InternalContext *ic = api->cls;
 248
 249   GNUNET_free(ic);
 250   GNUNET_free(api);
 251   return NULL;
 252 }
 253
 254 /* end of plugin_block_revocation.c */