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- /*
- This file is part of GNUnet.
- (C) 2010 Christian Grothoff (and other contributing authors)
- GNUnet is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published
- by the Free Software Foundation; either version 3, or (at your
- option) any later version.
- GNUnet is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with GNUnet; see the file COPYING. If not, write to the
- Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, USA.
- */
- /**
- * @file block/block.c
- * @brief library for data block manipulation
- * @author Christian Grothoff
- */
- #include "platform.h"
- #include "gnunet_util_lib.h"
- #include "gnunet_constants.h"
- #include "gnunet_signatures.h"
- #include "gnunet_block_lib.h"
- #include "gnunet_block_plugin.h"
- /**
- * Handle for a plugin.
- */
- struct Plugin
- {
- /**
- * Name of the shared library.
- */
- char *library_name;
- /**
- * Plugin API.
- */
- struct GNUNET_BLOCK_PluginFunctions *api;
- };
- /**
- * Handle to an initialized block library.
- */
- struct GNUNET_BLOCK_Context
- {
- /**
- * Array of our plugins.
- */
- struct Plugin **plugins;
- /**
- * Size of the 'plugins' array.
- */
- unsigned int num_plugins;
- /**
- * Our configuration.
- */
- const struct GNUNET_CONFIGURATION_Handle *cfg;
- };
- /**
- * Mingle hash with the mingle_number to produce different bits.
- *
- * @param in original hash code
- * @param mingle_number number for hash permutation
- * @param hc where to store the result.
- */
- void
- GNUNET_BLOCK_mingle_hash (const struct GNUNET_HashCode *in,
- uint32_t mingle_number,
- struct GNUNET_HashCode *hc)
- {
- struct GNUNET_HashCode m;
- GNUNET_CRYPTO_hash (&mingle_number, sizeof (uint32_t), &m);
- GNUNET_CRYPTO_hash_xor (&m, in, hc);
- }
- /**
- * Add a plugin to the list managed by the block library.
- *
- * @param cls the block context
- * @param library_name name of the plugin
- * @param lib_ret the plugin API
- */
- static void
- add_plugin (void *cls,
- const char *library_name,
- void *lib_ret)
- {
- struct GNUNET_BLOCK_Context *ctx = cls;
- struct GNUNET_BLOCK_PluginFunctions *api = lib_ret;
- struct Plugin *plugin;
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "Loading block plugin `%s'\n",
- library_name);
- plugin = GNUNET_new (struct Plugin);
- plugin->api = api;
- plugin->library_name = GNUNET_strdup (library_name);
- GNUNET_array_append (ctx->plugins, ctx->num_plugins, plugin);
- }
- /**
- * Create a block context. Loads the block plugins.
- *
- * @param cfg configuration to use
- * @return NULL on error
- */
- struct GNUNET_BLOCK_Context *
- GNUNET_BLOCK_context_create (const struct GNUNET_CONFIGURATION_Handle *cfg)
- {
- struct GNUNET_BLOCK_Context *ctx;
- ctx = GNUNET_new (struct GNUNET_BLOCK_Context);
- ctx->cfg = cfg;
- GNUNET_PLUGIN_load_all ("libgnunet_plugin_block_", NULL, &add_plugin, ctx);
- return ctx;
- }
- /**
- * Destroy the block context.
- *
- * @param ctx context to destroy
- */
- void
- GNUNET_BLOCK_context_destroy (struct GNUNET_BLOCK_Context *ctx)
- {
- unsigned int i;
- struct Plugin *plugin;
- for (i = 0; i < ctx->num_plugins; i++)
- {
- plugin = ctx->plugins[i];
- GNUNET_break (NULL ==
- GNUNET_PLUGIN_unload (plugin->library_name, plugin->api));
- GNUNET_free (plugin->library_name);
- GNUNET_free (plugin);
- }
- GNUNET_free (ctx->plugins);
- GNUNET_free (ctx);
- }
- /**
- * Find a plugin for the given type.
- *
- * @param ctx context to search
- * @param type type to look for
- * @return NULL if no matching plugin exists
- */
- static struct GNUNET_BLOCK_PluginFunctions *
- find_plugin (struct GNUNET_BLOCK_Context *ctx,
- enum GNUNET_BLOCK_Type type)
- {
- struct Plugin *plugin;
- unsigned int i;
- unsigned int j;
- for (i = 0; i < ctx->num_plugins; i++)
- {
- plugin = ctx->plugins[i];
- j = 0;
- while (0 != (plugin->api->types[j]))
- {
- if (type == plugin->api->types[j])
- return plugin->api;
- j++;
- }
- }
- return NULL;
- }
- /**
- * Function called to validate a reply or a request. For
- * request evaluation, simply pass "NULL" for the reply_block.
- * Note that it is assumed that the reply has already been
- * matched to the key (and signatures checked) as it would
- * be done with the "get_key" function.
- *
- * @param ctx block contxt
- * @param type block type
- * @param query original query (hash)
- * @param bf pointer to bloom filter associated with query; possibly updated (!)
- * @param bf_mutator mutation value for @a bf
- * @param xquery extended query data (can be NULL, depending on type)
- * @param xquery_size number of bytes in @a xquery
- * @param reply_block response to validate
- * @param reply_block_size number of bytes in @a reply_block
- * @return characterization of result
- */
- enum GNUNET_BLOCK_EvaluationResult
- GNUNET_BLOCK_evaluate (struct GNUNET_BLOCK_Context *ctx,
- enum GNUNET_BLOCK_Type type,
- const struct GNUNET_HashCode * query,
- struct GNUNET_CONTAINER_BloomFilter **bf,
- int32_t bf_mutator, const void *xquery,
- size_t xquery_size, const void *reply_block,
- size_t reply_block_size)
- {
- struct GNUNET_BLOCK_PluginFunctions *plugin = find_plugin (ctx, type);
- if (plugin == NULL)
- return GNUNET_BLOCK_EVALUATION_TYPE_NOT_SUPPORTED;
- return plugin->evaluate (plugin->cls, type, query, bf, bf_mutator, xquery,
- xquery_size, reply_block, reply_block_size);
- }
- /**
- * Function called to obtain the key for a block.
- *
- * @param ctx block context
- * @param type block type
- * @param block block to get the key for
- * @param block_size number of bytes in @a block
- * @param key set to the key (query) for the given block
- * @return #GNUNET_OK on success, #GNUNET_SYSERR if type not supported
- * (or if extracting a key from a block of this type does not work)
- */
- int
- GNUNET_BLOCK_get_key (struct GNUNET_BLOCK_Context *ctx,
- enum GNUNET_BLOCK_Type type, const void *block,
- size_t block_size, struct GNUNET_HashCode * key)
- {
- struct GNUNET_BLOCK_PluginFunctions *plugin = find_plugin (ctx, type);
- if (plugin == NULL)
- return GNUNET_BLOCK_EVALUATION_TYPE_NOT_SUPPORTED;
- return plugin->get_key (plugin->cls, type, block, block_size, key);
- }
- /**
- * How many bytes should a bloomfilter be if we have already seen
- * entry_count responses? Note that GNUNET_CONSTANTS_BLOOMFILTER_K gives us the number
- * of bits set per entry. Furthermore, we should not re-size the
- * filter too often (to keep it cheap).
- *
- * Since other peers will also add entries but not resize the filter,
- * we should generally pick a slightly larger size than what the
- * strict math would suggest.
- *
- * @param entry_count expected number of entries in the Bloom filter
- * @return must be a power of two and smaller or equal to 2^15.
- */
- static size_t
- compute_bloomfilter_size (unsigned int entry_count)
- {
- size_t size;
- unsigned int ideal = (entry_count * GNUNET_CONSTANTS_BLOOMFILTER_K) / 4;
- uint16_t max = 1 << 15;
- if (entry_count > max)
- return max;
- size = 8;
- while ((size < max) && (size < ideal))
- size *= 2;
- if (size > max)
- return max;
- return size;
- }
- /**
- * Construct a bloom filter that would filter out the given
- * results.
- *
- * @param bf_mutator mutation value to use
- * @param seen_results results already seen
- * @param seen_results_count number of entries in @a seen_results
- * @return NULL if seen_results_count is 0, otherwise a BF
- * that would match the given results.
- */
- struct GNUNET_CONTAINER_BloomFilter *
- GNUNET_BLOCK_construct_bloomfilter (int32_t bf_mutator,
- const struct GNUNET_HashCode * seen_results,
- unsigned int seen_results_count)
- {
- struct GNUNET_CONTAINER_BloomFilter *bf;
- struct GNUNET_HashCode mhash;
- unsigned int i;
- size_t nsize;
- nsize = compute_bloomfilter_size (seen_results_count);
- bf = GNUNET_CONTAINER_bloomfilter_init (NULL, nsize,
- GNUNET_CONSTANTS_BLOOMFILTER_K);
- for (i = 0; i < seen_results_count; i++)
- {
- GNUNET_BLOCK_mingle_hash (&seen_results[i], bf_mutator, &mhash);
- GNUNET_CONTAINER_bloomfilter_add (bf, &mhash);
- }
- return bf;
- }
- /* end of block.c */
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