1 files changed, 564 insertions, 0 deletions

diff --git a/src/service/namecache/namecache_api.c b/src/service/namecache/namecache_api.c
new file mode 100644
index 000000000..fb4b0e304
--- /dev/null
+++ b/src/service/namecache/namecache_api.c
@@ -0,0 +1,564 @@
+/*
+     This file is part of GNUnet.
+     Copyright (C) 2010-2013, 2016 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 namecache/namecache_api.c
+ * @brief API to access the NAMECACHE service
+ * @author Martin Schanzenbach
+ * @author Matthias Wachs
+ * @author Christian Grothoff
+ */
+
+#include "platform.h"
+#include "gnunet_util_lib.h"
+#include "gnunet_constants.h"
+#include "gnunet_gnsrecord_lib.h"
+#include "gnunet_signatures.h"
+#include "gnunet_namecache_service.h"
+#include "namecache.h"
+
+
+#define LOG(kind, ...) GNUNET_log_from (kind, "namecache-api", __VA_ARGS__)
+
+
+/**
+ * An QueueEntry used to store information for a pending
+ * NAMECACHE record operation
+ */
+struct GNUNET_NAMECACHE_QueueEntry
+{
+  /**
+   * Kept in a DLL.
+   */
+  struct GNUNET_NAMECACHE_QueueEntry *next;
+
+  /**
+   * Kept in a DLL.
+   */
+  struct GNUNET_NAMECACHE_QueueEntry *prev;
+
+  /**
+   * Main handle to access the namecache.
+   */
+  struct GNUNET_NAMECACHE_Handle *nsh;
+
+  /**
+   * Continuation to call
+   */
+  GNUNET_NAMECACHE_ContinuationWithStatus cont;
+
+  /**
+   * Closure for @e cont.
+   */
+  void *cont_cls;
+
+  /**
+   * Function to call with the blocks we get back; or NULL.
+   */
+  GNUNET_NAMECACHE_BlockProcessor block_proc;
+
+  /**
+   * Closure for @e block_proc.
+   */
+  void *block_proc_cls;
+
+  /**
+   * The operation id this zone iteration operation has
+   */
+  uint32_t op_id;
+};
+
+
+/**
+ * Connection to the NAMECACHE service.
+ */
+struct GNUNET_NAMECACHE_Handle
+{
+  /**
+   * Configuration to use.
+   */
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
+
+  /**
+   * Message queue to service.
+   */
+  struct GNUNET_MQ_Handle *mq;
+
+  /**
+   * Currently pending transmission request (or NULL).
+   */
+  struct GNUNET_CLIENT_TransmitHandle *th;
+
+  /**
+   * Head of pending namecache queue entries
+   */
+  struct GNUNET_NAMECACHE_QueueEntry *op_head;
+
+  /**
+   * Tail of pending namecache queue entries
+   */
+  struct GNUNET_NAMECACHE_QueueEntry *op_tail;
+
+  /**
+   * Reconnect task
+   */
+  struct GNUNET_SCHEDULER_Task *reconnect_task;
+
+  /**
+   * Delay introduced before we reconnect.
+   */
+  struct GNUNET_TIME_Relative reconnect_delay;
+
+  /**
+   * Should we reconnect to service due to some serious error?
+   */
+  int reconnect;
+
+  /**
+   * The last operation id used for a NAMECACHE operation
+   */
+  uint32_t last_op_id_used;
+};
+
+
+/**
+ * Disconnect from service and then reconnect.
+ *
+ * @param h our handle
+ */
+static void
+force_reconnect (struct GNUNET_NAMECACHE_Handle *h);
+
+
+/**
+ * Find queue entry for the given @a rid.
+ *
+ * @param h handle to search
+ * @param rid request ID to look for
+ * @return NULL if not found, otherwise the queue entry (removed from the queue)
+ */
+static struct GNUNET_NAMECACHE_QueueEntry *
+find_qe (struct GNUNET_NAMECACHE_Handle *h,
+         uint32_t rid)
+{
+  struct GNUNET_NAMECACHE_QueueEntry *qe;
+
+  for (qe = h->op_head; qe != NULL; qe = qe->next)
+  {
+    if (qe->op_id == rid)
+    {
+      GNUNET_CONTAINER_DLL_remove (h->op_head,
+                                   h->op_tail,
+                                   qe);
+      return qe;
+    }
+  }
+  return NULL;
+}
+
+
+/**
+ * Handle an incoming message of type
+ * #GNUNET_MESSAGE_TYPE_NAMECACHE_LOOKUP_BLOCK_RESPONSE.
+ *
+ * @param cls the `struct GNUNET_NAMECACHE_Handle`
+ * @param msg the message we received
+ */
+static int
+check_lookup_block_response (void *cls,
+                             const struct LookupBlockResponseMessage *msg)
+{
+  /* any length will do, format validation is in handler */
+  return GNUNET_OK;
+}
+
+
+/**
+ * Handle an incoming message of type
+ * #GNUNET_MESSAGE_TYPE_NAMECACHE_LOOKUP_BLOCK_RESPONSE.
+ *
+ * @param cls the `struct GNUNET_NAMECACHE_Handle`
+ * @param msg the message we received
+ */
+static void
+handle_lookup_block_response (void *cls,
+                              const struct LookupBlockResponseMessage *msg)
+{
+  struct GNUNET_NAMECACHE_Handle *h = cls;
+  size_t size;
+  struct GNUNET_NAMECACHE_QueueEntry *qe;
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received LOOKUP_BLOCK_RESPONSE\n");
+  qe = find_qe (h,
+                ntohl (msg->gns_header.r_id));
+  if (NULL == qe)
+    return;
+  if (0 == GNUNET_TIME_absolute_ntoh (msg->expire).abs_value_us)
+  {
+    /* no match found */
+    if (NULL != qe->block_proc)
+      qe->block_proc (qe->block_proc_cls,
+                      NULL);
+    GNUNET_free (qe);
+    return;
+  }
+  size = ntohs (msg->gns_header.header.size)
+         - sizeof(struct LookupBlockResponseMessage);
+  {
+    char buf[size] GNUNET_ALIGN;
+    struct GNUNET_GNSRECORD_Block *block;
+
+    memset (buf, 0, size);
+    block = (struct GNUNET_GNSRECORD_Block *) buf;
+    GNUNET_memcpy (block,
+                   &msg[1],
+                   size);
+    if (GNUNET_OK !=
+        GNUNET_GNSRECORD_block_verify (block))
+    {
+      GNUNET_break (0);
+      if (NULL != qe->block_proc)
+        qe->block_proc (qe->block_proc_cls,
+                        NULL);
+      force_reconnect (h);
+    }
+    else
+    {
+      if (NULL != qe->block_proc)
+        qe->block_proc (qe->block_proc_cls,
+                        block);
+    }
+  }
+  GNUNET_free (qe);
+}
+
+
+/**
+ * Handle an incoming message of type
+ * #GNUNET_MESSAGE_TYPE_NAMECACHE_BLOCK_CACHE_RESPONSE
+ *
+ * @param cls the `struct GNUNET_NAMECACHE_Handle`
+ * @param msg the message we received
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on error and we did NOT notify the client
+ */
+static void
+handle_block_cache_response (void *cls,
+                             const struct BlockCacheResponseMessage *msg)
+{
+  struct GNUNET_NAMECACHE_Handle *h = cls;
+  struct GNUNET_NAMECACHE_QueueEntry *qe;
+  int res;
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received BLOCK_CACHE_RESPONSE\n");
+  qe = find_qe (h,
+                ntohl (msg->gns_header.r_id));
+  if (NULL == qe)
+    return;
+  res = ntohl (msg->op_result);
+  /* TODO: add actual error message from namecache to response... */
+  if (NULL != qe->cont)
+    qe->cont (qe->cont_cls,
+              res,
+              (GNUNET_OK == res)
+              ? NULL
+              : _ ("Namecache failed to cache block"));
+  GNUNET_free (qe);
+}
+
+
+/**
+ * Generic error handler, called with the appropriate error code and
+ * the same closure specified at the creation of the message queue.
+ * Not every message queue implementation supports an error handler.
+ *
+ * @param cls closure with the `struct GNUNET_NAMECACHE_Handle *`
+ * @param error error code
+ */
+static void
+mq_error_handler (void *cls,
+                  enum GNUNET_MQ_Error error)
+{
+  struct GNUNET_NAMECACHE_Handle *h = cls;
+
+  force_reconnect (h);
+}
+
+
+/**
+ * Reconnect to namecache service.
+ *
+ * @param h the handle to the NAMECACHE service
+ */
+static void
+reconnect (struct GNUNET_NAMECACHE_Handle *h)
+{
+  struct GNUNET_MQ_MessageHandler handlers[] = {
+    GNUNET_MQ_hd_var_size (lookup_block_response,
+                           GNUNET_MESSAGE_TYPE_NAMECACHE_LOOKUP_BLOCK_RESPONSE,
+                           struct LookupBlockResponseMessage,
+                           h),
+    GNUNET_MQ_hd_fixed_size (block_cache_response,
+                             GNUNET_MESSAGE_TYPE_NAMECACHE_BLOCK_CACHE_RESPONSE,
+                             struct BlockCacheResponseMessage,
+                             h),
+    GNUNET_MQ_handler_end ()
+  };
+
+  GNUNET_assert (NULL == h->mq);
+  h->mq = GNUNET_CLIENT_connect (h->cfg,
+                                 "namecache",
+                                 handlers,
+                                 &mq_error_handler,
+                                 h);
+}
+
+
+/**
+ * Re-establish the connection to the service.
+ *
+ * @param cls handle to use to re-connect.
+ */
+static void
+reconnect_task (void *cls)
+{
+  struct GNUNET_NAMECACHE_Handle *h = cls;
+
+  h->reconnect_task = NULL;
+  reconnect (h);
+}
+
+
+/**
+ * Disconnect from service and then reconnect.
+ *
+ * @param h our handle
+ */
+static void
+force_reconnect (struct GNUNET_NAMECACHE_Handle *h)
+{
+  struct GNUNET_NAMECACHE_QueueEntry *qe;
+
+  h->reconnect = GNUNET_NO;
+  GNUNET_MQ_destroy (h->mq);
+  h->mq = NULL;
+  while (NULL != (qe = h->op_head))
+  {
+    GNUNET_CONTAINER_DLL_remove (h->op_head,
+                                 h->op_tail,
+                                 qe);
+    if (NULL != qe->cont)
+      qe->cont (qe->cont_cls,
+                GNUNET_SYSERR,
+                _ ("Error communicating with namecache service"));
+    GNUNET_free (qe);
+  }
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Reconnecting to namecache\n");
+  h->reconnect_delay = GNUNET_TIME_STD_BACKOFF (h->reconnect_delay);
+  h->reconnect_task = GNUNET_SCHEDULER_add_delayed (h->reconnect_delay,
+                                                    &reconnect_task,
+                                                    h);
+}
+
+
+/**
+ * Get a fresh operation id to distinguish between namecache requests
+ *
+ * @param h the namecache handle
+ * @return next operation id to use
+ */
+static uint32_t
+get_op_id (struct GNUNET_NAMECACHE_Handle *h)
+{
+  return h->last_op_id_used++;
+}
+
+
+/**
+ * Initialize the connection with the NAMECACHE service.
+ *
+ * @param cfg configuration to use
+ * @return handle to the GNS service, or NULL on error
+ */
+struct GNUNET_NAMECACHE_Handle *
+GNUNET_NAMECACHE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg)
+{
+  struct GNUNET_NAMECACHE_Handle *h;
+
+  h = GNUNET_new (struct GNUNET_NAMECACHE_Handle);
+  h->cfg = cfg;
+  reconnect (h);
+  if (NULL == h->mq)
+  {
+    GNUNET_free (h);
+    return NULL;
+  }
+  return h;
+}
+
+
+/**
+ * Disconnect from the namecache service (and free associated
+ * resources).
+ *
+ * @param h handle to the namecache
+ */
+void
+GNUNET_NAMECACHE_disconnect (struct GNUNET_NAMECACHE_Handle *h)
+{
+  struct GNUNET_NAMECACHE_QueueEntry *q;
+
+  GNUNET_break (NULL == h->op_head);
+  while (NULL != (q = h->op_head))
+  {
+    GNUNET_CONTAINER_DLL_remove (h->op_head,
+                                 h->op_tail,
+                                 q);
+    GNUNET_free (q);
+  }
+  if (NULL != h->mq)
+  {
+    GNUNET_MQ_destroy (h->mq);
+    h->mq = NULL;
+  }
+  if (NULL != h->reconnect_task)
+  {
+    GNUNET_SCHEDULER_cancel (h->reconnect_task);
+    h->reconnect_task = NULL;
+  }
+  GNUNET_free (h);
+}
+
+
+/**
+ * Store an item in the namecache.  If the item is already present,
+ * it is replaced with the new record.
+ *
+ * @param h handle to the namecache
+ * @param block block to store
+ * @param cont continuation to call when done
+ * @param cont_cls closure for @a cont
+ * @return handle to abort the request, NULL on error
+ */
+struct GNUNET_NAMECACHE_QueueEntry *
+GNUNET_NAMECACHE_block_cache (struct GNUNET_NAMECACHE_Handle *h,
+                              const struct GNUNET_GNSRECORD_Block *block,
+                              GNUNET_NAMECACHE_ContinuationWithStatus cont,
+                              void *cont_cls)
+{
+  struct GNUNET_NAMECACHE_QueueEntry *qe;
+  struct BlockCacheMessage *msg;
+  struct GNUNET_MQ_Envelope *env;
+  uint32_t rid;
+  size_t blen;
+
+  if (NULL == h->mq)
+    return NULL;
+  blen = GNUNET_GNSRECORD_block_get_size (block);
+  rid = get_op_id (h);
+  qe = GNUNET_new (struct GNUNET_NAMECACHE_QueueEntry);
+  qe->nsh = h;
+  qe->cont = cont;
+  qe->cont_cls = cont_cls;
+  qe->op_id = rid;
+  GNUNET_CONTAINER_DLL_insert_tail (h->op_head,
+                                    h->op_tail,
+                                    qe);
+  /* send msg */
+  env = GNUNET_MQ_msg_extra (msg,
+                             blen,
+                             GNUNET_MESSAGE_TYPE_NAMECACHE_BLOCK_CACHE);
+  msg->gns_header.r_id = htonl (rid);
+  GNUNET_memcpy (&msg[1],
+                 block,
+                 blen);
+  GNUNET_MQ_send (h->mq,
+                  env);
+  return qe;
+}
+
+
+/**
+ * Get a result for a particular key from the namecache.  The processor
+ * will only be called once.
+ *
+ * @param h handle to the namecache
+ * @param derived_hash hash of zone key combined with name to lookup
+ * @param proc function to call on the matching block, or with
+ *        NULL if there is no matching block
+ * @param proc_cls closure for @a proc
+ * @return a handle that can be used to cancel, NULL on error
+ */
+struct GNUNET_NAMECACHE_QueueEntry *
+GNUNET_NAMECACHE_lookup_block (struct GNUNET_NAMECACHE_Handle *h,
+                               const struct GNUNET_HashCode *derived_hash,
+                               GNUNET_NAMECACHE_BlockProcessor proc,
+                               void *proc_cls)
+{
+  struct GNUNET_NAMECACHE_QueueEntry *qe;
+  struct LookupBlockMessage *msg;
+  struct GNUNET_MQ_Envelope *env;
+  uint32_t rid;
+
+  if (NULL == h->mq)
+    return NULL;
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Looking for block under %s\n",
+       GNUNET_h2s (derived_hash));
+  rid = get_op_id (h);
+  qe = GNUNET_new (struct GNUNET_NAMECACHE_QueueEntry);
+  qe->nsh = h;
+  qe->block_proc = proc;
+  qe->block_proc_cls = proc_cls;
+  qe->op_id = rid;
+  GNUNET_CONTAINER_DLL_insert_tail (h->op_head,
+                                    h->op_tail,
+                                    qe);
+  env = GNUNET_MQ_msg (msg,
+                       GNUNET_MESSAGE_TYPE_NAMECACHE_LOOKUP_BLOCK);
+  msg->gns_header.r_id = htonl (rid);
+  msg->query = *derived_hash;
+  GNUNET_MQ_send (h->mq,
+                  env);
+  return qe;
+}
+
+
+/**
+ * Cancel a namecache operation.  The final callback from the
+ * operation must not have been done yet.
+ *
+ * @param qe operation to cancel
+ */
+void
+GNUNET_NAMECACHE_cancel (struct GNUNET_NAMECACHE_QueueEntry *qe)
+{
+  struct GNUNET_NAMECACHE_Handle *h = qe->nsh;
+
+  GNUNET_CONTAINER_DLL_remove (h->op_head,
+                               h->op_tail,
+                               qe);
+  GNUNET_free (qe);
+}
+
+
+/* end of namecache_api.c */