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/*
This file is part of GNUnet
Copyright (C) 2013, 2017 GNUnet e.V.
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., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
/**
* @file dns/plugin_block_dns.c
* @brief block plugin for advertising a DNS exit service
* @author Christian Grothoff
*
* Note that this plugin might more belong with EXIT and PT
* as those two are using this type of block. Still, this
* might be a natural enough place for people to find the code...
*/
#include "platform.h"
#include "gnunet_block_plugin.h"
#include "block_dns.h"
#include "gnunet_signatures.h"
#include "gnunet_block_group_lib.h"
/**
* Number of bits we set per entry in the bloomfilter.
* Do not change!
*/
#define BLOOMFILTER_K 16
/**
* Create a new block group.
*
* @param ctx block context in which the block group is created
* @param type type of the block for which we are creating the group
* @param nonce random value used to seed the group creation
* @param raw_data optional serialized prior state of the group, NULL if unavailable/fresh
* @param raw_data_size number of bytes in @a raw_data, 0 if unavailable/fresh
* @param va variable arguments specific to @a type
* @return block group handle, NULL if block groups are not supported
* by this @a type of block (this is not an error)
*/
static struct GNUNET_BLOCK_Group *
block_plugin_dns_create_group (void *cls,
enum GNUNET_BLOCK_Type type,
uint32_t nonce,
const void *raw_data,
size_t raw_data_size,
va_list va)
{
unsigned int bf_size;
const char *guard;
guard = va_arg (va, const char *);
if (0 == strcmp (guard,
"seen-set-size"))
bf_size = GNUNET_BLOCK_GROUP_compute_bloomfilter_size (va_arg (va, unsigned int),
BLOOMFILTER_K);
else if (0 == strcmp (guard,
"filter-size"))
bf_size = va_arg (va, unsigned int);
else
{
GNUNET_break (0);
bf_size = 8;
}
GNUNET_break (NULL == va_arg (va, const char *));
return GNUNET_BLOCK_GROUP_bf_create (cls,
bf_size,
BLOOMFILTER_K,
type,
nonce,
raw_data,
raw_data_size);
}
/**
* Function called to validate a reply or a request. For
* request evaluation, simply pass "NULL" for the reply_block.
*
* @param cls closure
* @param ctx block context
* @param type block type
* @param bg group to evaluate against
* @param eo control flags
* @param query original query (hash)
* @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
*/
static enum GNUNET_BLOCK_EvaluationResult
block_plugin_dns_evaluate (void *cls,
struct GNUNET_BLOCK_Context *ctx,
enum GNUNET_BLOCK_Type type,
struct GNUNET_BLOCK_Group *bg,
enum GNUNET_BLOCK_EvaluationOptions eo,
const struct GNUNET_HashCode * query,
const void *xquery,
size_t xquery_size,
const void *reply_block,
size_t reply_block_size)
{
const struct GNUNET_DNS_Advertisement *ad;
struct GNUNET_HashCode phash;
switch (type)
{
case GNUNET_BLOCK_TYPE_DNS:
if (0 != xquery_size)
return GNUNET_BLOCK_EVALUATION_REQUEST_INVALID;
if (NULL == reply_block)
return GNUNET_BLOCK_EVALUATION_REQUEST_VALID;
if (sizeof (struct GNUNET_DNS_Advertisement) != reply_block_size)
{
GNUNET_break_op (0);
return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
}
ad = reply_block;
if (ntohl (ad->purpose.size) !=
sizeof (struct GNUNET_DNS_Advertisement) -
sizeof (struct GNUNET_CRYPTO_EddsaSignature))
{
GNUNET_break_op (0);
return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
}
if (0 ==
GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh
(ad->expiration_time)).rel_value_us)
{
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"DNS advertisement has expired\n");
return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
}
if (GNUNET_OK !=
GNUNET_CRYPTO_eddsa_verify (GNUNET_SIGNATURE_PURPOSE_DNS_RECORD,
&ad->purpose,
&ad->signature,
&ad->peer.public_key))
{
GNUNET_break_op (0);
return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
}
GNUNET_CRYPTO_hash (reply_block,
reply_block_size,
&phash);
if (GNUNET_YES ==
GNUNET_BLOCK_GROUP_bf_test_and_set (bg,
&phash))
return GNUNET_BLOCK_EVALUATION_OK_DUPLICATE;
return GNUNET_BLOCK_EVALUATION_OK_MORE;
default:
return GNUNET_BLOCK_EVALUATION_TYPE_NOT_SUPPORTED;
}
}
/**
* Function called to obtain the key for a block.
*
* @param cls closure
* @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)
*/
static int
block_plugin_dns_get_key (void *cls,
enum GNUNET_BLOCK_Type type,
const void *block,
size_t block_size,
struct GNUNET_HashCode *key)
{
/* we cannot extract a key from a block of this type */
return GNUNET_SYSERR;
}
/**
* Entry point for the plugin.
*/
void *
libgnunet_plugin_block_dns_init (void *cls)
{
static enum GNUNET_BLOCK_Type types[] =
{
GNUNET_BLOCK_TYPE_DNS,
GNUNET_BLOCK_TYPE_ANY /* end of list */
};
struct GNUNET_BLOCK_PluginFunctions *api;
api = GNUNET_new (struct GNUNET_BLOCK_PluginFunctions);
api->evaluate = &block_plugin_dns_evaluate;
api->get_key = &block_plugin_dns_get_key;
api->create_group = &block_plugin_dns_create_group;
api->types = types;
return api;
}
/**
* Exit point from the plugin.
*/
void *
libgnunet_plugin_block_dns_done (void *cls)
{
struct GNUNET_BLOCK_PluginFunctions *api = cls;
GNUNET_free (api);
return NULL;
}
/* end of plugin_block_dns.c */
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