1 files changed, 290 insertions, 0 deletions

diff --git a/src/plugin/dns/plugin_block_dns.c b/src/plugin/dns/plugin_block_dns.c
new file mode 100644
index 000000000..1bbd7f750
--- /dev/null
+++ b/src/plugin/dns/plugin_block_dns.c
@@ -0,0 +1,290 @@
+/*
+     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 Affero General Public License as published
+     by the Free Software Foundation, either version 3 of the License,
+     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
+     Affero General Public License for more details.
+
+     You should have received a copy of the GNU Affero General Public License
+     along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+     SPDX-License-Identifier: AGPL3.0-or-later
+ */
+
+/**
+ * @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 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,
+                               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,
+                                       raw_data,
+                                       raw_data_size);
+}
+
+
+/**
+ * Function called to validate a query.
+ *
+ * @param cls closure
+ * @param type block type
+ * @param query original query (hash)
+ * @param xquery extrended query data (can be NULL, depending on type)
+ * @param xquery_size number of bytes in @a xquery
+ * @return #GNUNET_OK if the query is fine, #GNUNET_NO if not
+ */
+static enum GNUNET_GenericReturnValue
+block_plugin_dns_check_query (void *cls,
+                              enum GNUNET_BLOCK_Type type,
+                              const struct GNUNET_HashCode *query,
+                              const void *xquery,
+                              size_t xquery_size)
+{
+  switch (type)
+  {
+  case GNUNET_BLOCK_TYPE_DNS:
+    if (0 != xquery_size)
+    {
+      GNUNET_break_op (0);
+      return GNUNET_NO;
+    }
+    return GNUNET_OK;
+  default:
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+}
+
+
+/**
+ * Function called to validate a block for storage.
+ *
+ * @param cls closure
+ * @param type block type
+ * @param block block data to validate
+ * @param block_size number of bytes in @a block
+ * @return #GNUNET_OK if the block is fine, #GNUNET_NO if not
+ */
+static enum GNUNET_GenericReturnValue
+block_plugin_dns_check_block (void *cls,
+                              enum GNUNET_BLOCK_Type type,
+                              const void *block,
+                              size_t block_size)
+{
+  const struct GNUNET_DNS_Advertisement *ad;
+
+  switch (type)
+  {
+  case GNUNET_BLOCK_TYPE_DNS:
+    if (sizeof(struct GNUNET_DNS_Advertisement) != block_size)
+    {
+      GNUNET_break_op (0);
+      return GNUNET_NO;
+    }
+    ad = block;
+
+    if (ntohl (ad->purpose.size) !=
+        sizeof(struct GNUNET_DNS_Advertisement)
+        - sizeof(struct GNUNET_CRYPTO_EddsaSignature))
+    {
+      GNUNET_break_op (0);
+      return GNUNET_NO;
+    }
+    if (GNUNET_TIME_absolute_is_past (
+          GNUNET_TIME_absolute_ntoh (ad->expiration_time)))
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  "DNS advertisement has expired\n");
+      return GNUNET_NO;
+    }
+    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_NO;
+    }
+    return GNUNET_OK;
+  default:
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+}
+
+
+/**
+ * Function called to validate a reply to a request.  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 GetKeyFunction and the
+ * BlockEvaluationFunction.
+ *
+ * @param cls closure
+ * @param type block type
+ * @param group which block group to use for evaluation
+ * @param query original query (hash)
+ * @param xquery extrended 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_ReplyEvaluationResult
+block_plugin_dns_check_reply (
+  void *cls,
+  enum GNUNET_BLOCK_Type type,
+  struct GNUNET_BLOCK_Group *group,
+  const struct GNUNET_HashCode *query,
+  const void *xquery,
+  size_t xquery_size,
+  const void *reply_block,
+  size_t reply_block_size)
+{
+  struct GNUNET_HashCode phash;
+
+  switch (type)
+  {
+  case GNUNET_BLOCK_TYPE_DNS:
+    GNUNET_CRYPTO_hash (reply_block,
+                        reply_block_size,
+                        &phash);
+    if (GNUNET_YES ==
+        GNUNET_BLOCK_GROUP_bf_test_and_set (group,
+                                            &phash))
+      return GNUNET_BLOCK_REPLY_OK_DUPLICATE;
+    return GNUNET_BLOCK_REPLY_OK_MORE;
+  default:
+    GNUNET_break (0);
+    return GNUNET_BLOCK_REPLY_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 enum GNUNET_GenericReturnValue
+block_plugin_dns_get_key (void *cls,
+                          enum GNUNET_BLOCK_Type type,
+                          const void *block,
+                          size_t block_size,
+                          struct GNUNET_HashCode *key)
+{
+  if (GNUNET_BLOCK_TYPE_DNS != type)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_NO;
+}
+
+
+/**
+ * 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->get_key = &block_plugin_dns_get_key;
+  api->check_query = &block_plugin_dns_check_query;
+  api->check_block = &block_plugin_dns_check_block;
+  api->check_reply = &block_plugin_dns_check_reply;
+  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 */