initial import from gnunet.git

1 files changed, 1285 insertions, 0 deletions

diff --git a/src/psycstore/psycstore_api.c b/src/psycstore/psycstore_api.c
new file mode 100644
index 0000000..ab4cd0f
--- /dev/null
+++ b/src/psycstore/psycstore_api.c
@@ -0,0 +1,1285 @@
+/*
+ * This file is part of GNUnet
+ * Copyright (C) 2013 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 psycstore/psycstore_api.c
+ * @brief API to interact with the PSYCstore service
+ * @author Gabor X Toth
+ * @author Christian Grothoff
+ */
+
+#include <inttypes.h>
+
+#include "platform.h"
+#include "gnunet_util_lib.h"
+#include "gnunet_constants.h"
+#include "gnunet_protocols.h"
+#include "gnunet_psycstore_service.h"
+#include "gnunet_multicast_service.h"
+#include "psycstore.h"
+
+#define LOG(kind,...) GNUNET_log_from (kind, "psycstore-api",__VA_ARGS__)
+
+/**
+ * Handle for an operation with the PSYCstore service.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle
+{
+
+  /**
+   * Main PSYCstore handle.
+   */
+  struct GNUNET_PSYCSTORE_Handle *h;
+
+  /**
+   * Data callbacks.
+   */
+  union {
+    GNUNET_PSYCSTORE_FragmentCallback fragment_cb;
+    GNUNET_PSYCSTORE_CountersCallback counters_cb;
+    GNUNET_PSYCSTORE_StateCallback state_cb;
+  };
+
+  /**
+   * Closure for callbacks.
+   */
+  void *cls;
+
+  /**
+   * Message envelope.
+   */
+  struct GNUNET_MQ_Envelope *env;
+
+  /**
+   * Operation ID.
+   */
+  uint64_t op_id;
+};
+
+
+/**
+ * Handle for the service.
+ */
+struct GNUNET_PSYCSTORE_Handle
+{
+  /**
+   * Configuration to use.
+   */
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
+
+  /**
+   * Client connection.
+   */
+  struct GNUNET_MQ_Handle *mq;
+
+  /**
+   * Async operations.
+   */
+  struct GNUNET_OP_Handle *op;
+
+  /**
+   * Task doing exponential back-off trying to reconnect.
+   */
+  struct GNUNET_SCHEDULER_Task *reconnect_task;
+
+  /**
+   * Delay for next connect retry.
+   */
+  struct GNUNET_TIME_Relative reconnect_delay;
+
+
+  GNUNET_PSYCSTORE_FragmentCallback *fragment_cb;
+
+  GNUNET_PSYCSTORE_CountersCallback *counters_cb;
+
+  GNUNET_PSYCSTORE_StateCallback *state_cb;
+  /**
+   * Closure for callbacks.
+   */
+  void *cb_cls;
+};
+
+
+static int
+check_result_code (void *cls, const struct OperationResult *opres)
+{
+  uint16_t size = ntohs (opres->header.size);
+  const char *str = (const char *) &opres[1];
+  if ( (sizeof (*opres) < size) &&
+       ('\0' != str[size - sizeof (*opres) - 1]) )
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+
+  return GNUNET_OK;
+}
+
+
+static void
+handle_result_code (void *cls, const struct OperationResult *opres)
+{
+  struct GNUNET_PSYCSTORE_Handle *h = cls;
+  struct GNUNET_PSYCSTORE_OperationHandle *op = NULL;
+  uint16_t size = ntohs (opres->header.size);
+
+  const char *
+    str = (sizeof (*opres) < size) ? (const char *) &opres[1] : "";
+
+  if (GNUNET_YES == GNUNET_OP_result (h->op, GNUNET_ntohll (opres->op_id),
+                                      GNUNET_ntohll (opres->result_code) + INT64_MIN,
+                                      str, size - sizeof (*opres), (void **) &op))
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "handle_result_code: Received result message with OP ID: %" PRIu64 "\n",
+         GNUNET_ntohll (opres->op_id));
+    GNUNET_free (op);
+  }
+  else
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "handle_result_code: No callback registered for OP ID %" PRIu64 ".\n",
+         GNUNET_ntohll (opres->op_id));
+  }
+  h->reconnect_delay = GNUNET_TIME_UNIT_MILLISECONDS;
+}
+
+
+static void
+handle_result_counters (void *cls, const struct CountersResult *cres)
+{
+  struct GNUNET_PSYCSTORE_Handle *h = cls;
+  struct GNUNET_PSYCSTORE_OperationHandle *op = NULL;
+
+  if (GNUNET_YES == GNUNET_OP_get (h->op, GNUNET_ntohll (cres->op_id),
+                                   NULL, NULL, (void **) &op))
+  {
+    GNUNET_assert (NULL != op);
+    if (NULL != op->counters_cb)
+    {
+      op->counters_cb (op->cls,
+                       ntohl (cres->result_code),
+                       GNUNET_ntohll (cres->max_fragment_id),
+                       GNUNET_ntohll (cres->max_message_id),
+                       GNUNET_ntohll (cres->max_group_generation),
+                       GNUNET_ntohll (cres->max_state_message_id));
+    }
+    GNUNET_OP_remove (h->op, GNUNET_ntohll (cres->op_id));
+    GNUNET_free (op);
+  }
+  else
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "handle_result_counters: No callback registered for OP ID %" PRIu64 ".\n",
+         GNUNET_ntohll (cres->op_id));
+  }
+  h->reconnect_delay = GNUNET_TIME_UNIT_MILLISECONDS;
+}
+
+
+static int
+check_result_fragment (void *cls, const struct FragmentResult *fres)
+{
+  uint16_t size = ntohs (fres->header.size);
+  struct GNUNET_MULTICAST_MessageHeader *mmsg =
+    (struct GNUNET_MULTICAST_MessageHeader *) &fres[1];
+  if (sizeof (*fres) + sizeof (*mmsg) < size
+      && sizeof (*fres) + ntohs (mmsg->header.size) != size)
+  {
+    LOG (GNUNET_ERROR_TYPE_ERROR,
+         "check_result_fragment: Received message with invalid length %lu bytes.\n",
+         size, sizeof (*fres));
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
+static void
+handle_result_fragment (void *cls, const struct FragmentResult *fres)
+{
+  struct GNUNET_PSYCSTORE_Handle *h = cls;
+  struct GNUNET_PSYCSTORE_OperationHandle *op = NULL;
+
+  if (GNUNET_YES == GNUNET_OP_get (h->op, GNUNET_ntohll (fres->op_id),
+                                   NULL, NULL, (void **) &op))
+  {
+    GNUNET_assert (NULL != op);
+    if (NULL != op->fragment_cb)
+      op->fragment_cb (op->cls,
+                       (struct GNUNET_MULTICAST_MessageHeader *) &fres[1],
+                       ntohl (fres->psycstore_flags));
+    //GNUNET_OP_remove (h->op, GNUNET_ntohll (fres->op_id));
+    //GNUNET_free (op);
+  }
+  else
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "handle_result_fragment: No callback registered for OP ID %" PRIu64 ".\n",
+         GNUNET_ntohll (fres->op_id));
+  }
+  h->reconnect_delay = GNUNET_TIME_UNIT_MILLISECONDS;
+}
+
+
+static int
+check_result_state (void *cls, const struct StateResult *sres)
+{
+  const char *name = (const char *) &sres[1];
+  uint16_t size = ntohs (sres->header.size);
+  uint16_t name_size = ntohs (sres->name_size);
+
+  if (name_size <= 2
+      || size - sizeof (*sres) < name_size
+      || '\0' != name[name_size - 1])
+  {
+    LOG (GNUNET_ERROR_TYPE_ERROR,
+         "check_result_state: Received state result message with invalid name.\n");
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
+static void
+handle_result_state (void *cls, const struct StateResult *sres)
+{
+  struct GNUNET_PSYCSTORE_Handle *h = cls;
+  struct GNUNET_PSYCSTORE_OperationHandle *op = NULL;
+
+  const char *name = (const char *) &sres[1];
+  uint16_t name_size = ntohs (sres->name_size);
+
+  if (GNUNET_YES == GNUNET_OP_get (h->op, GNUNET_ntohll (sres->op_id),
+                                   NULL, NULL, (void **) &op))
+  {
+    GNUNET_assert (NULL != op);
+    if (NULL != op->state_cb)
+       op->state_cb (op->cls, name, (char *) &sres[1] + name_size,
+                     ntohs (sres->header.size) - sizeof (*sres) - name_size);
+    //GNUNET_OP_remove (h->op, GNUNET_ntohll (sres->op_id));
+    //GNUNET_free (op);
+  }
+  else
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "handle_result_state: No callback registered for OP ID %" PRIu64 ".\n",
+         GNUNET_ntohll (sres->op_id));
+  }
+  h->reconnect_delay = GNUNET_TIME_UNIT_MILLISECONDS;
+}
+
+
+static void
+reconnect (void *cls);
+
+
+/**
+ * Client disconnected from service.
+ *
+ * Reconnect after backoff period.=
+ */
+static void
+disconnected (void *cls, enum GNUNET_MQ_Error error)
+{
+  struct GNUNET_PSYCSTORE_Handle *h = cls;
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Origin client disconnected (%d), re-connecting\n",
+       (int) error);
+  if (NULL != h->mq)
+  {
+    GNUNET_MQ_destroy (h->mq);
+    GNUNET_OP_destroy (h->op);
+    h->mq = NULL;
+    h->op = NULL;
+  }
+
+  h->reconnect_task = GNUNET_SCHEDULER_add_delayed (h->reconnect_delay,
+                                                    &reconnect, h);
+  h->reconnect_delay = GNUNET_TIME_STD_BACKOFF (h->reconnect_delay);
+}
+
+
+static void
+do_connect (struct GNUNET_PSYCSTORE_Handle *h)
+{
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Connecting to PSYCstore service.\n");
+
+  struct GNUNET_MQ_MessageHandler handlers[] = {
+    GNUNET_MQ_hd_var_size (result_code,
+                           GNUNET_MESSAGE_TYPE_PSYCSTORE_RESULT_CODE,
+                           struct OperationResult,
+                           h),
+    GNUNET_MQ_hd_fixed_size (result_counters,
+                             GNUNET_MESSAGE_TYPE_PSYCSTORE_RESULT_COUNTERS,
+                             struct CountersResult,
+                             h),
+    GNUNET_MQ_hd_var_size (result_fragment,
+                           GNUNET_MESSAGE_TYPE_PSYCSTORE_RESULT_FRAGMENT,
+                           struct FragmentResult,
+                           h),
+    GNUNET_MQ_hd_var_size (result_state,
+                           GNUNET_MESSAGE_TYPE_PSYCSTORE_RESULT_STATE,
+                           struct StateResult,
+                           h),
+    GNUNET_MQ_handler_end ()
+  };
+
+  h->op = GNUNET_OP_create ();
+  GNUNET_assert (NULL == h->mq);
+  h->mq = GNUNET_CLIENT_connect (h->cfg, "psycstore",
+                                 handlers, disconnected, h);
+  GNUNET_assert (NULL != h->mq);
+}
+
+
+/**
+ * Try again to connect to the PSYCstore service.
+ *
+ * @param cls Handle to the PSYCstore service.
+ */
+static void
+reconnect (void *cls)
+{
+  struct GNUNET_PSYCSTORE_Handle *h = cls;
+
+  h->reconnect_task = NULL;
+  do_connect (cls);
+}
+
+
+/**
+ * Connect to the PSYCstore service.
+ *
+ * @param cfg The configuration to use
+ * @return Handle to use
+ */
+struct GNUNET_PSYCSTORE_Handle *
+GNUNET_PSYCSTORE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg)
+{
+  struct GNUNET_PSYCSTORE_Handle *h
+    = GNUNET_new (struct GNUNET_PSYCSTORE_Handle);
+  h->cfg = cfg;
+  h->reconnect_delay = GNUNET_TIME_UNIT_MILLISECONDS;
+  do_connect (h);
+  return h;
+}
+
+
+/**
+ * Disconnect from PSYCstore service
+ *
+ * @param h Handle to destroy
+ */
+void
+GNUNET_PSYCSTORE_disconnect (struct GNUNET_PSYCSTORE_Handle *h)
+{
+  GNUNET_assert (NULL != h);
+  if (h->reconnect_task != NULL)
+  {
+    GNUNET_SCHEDULER_cancel (h->reconnect_task);
+    h->reconnect_task = NULL;
+  }
+  if (NULL != h->mq)
+  {
+    // FIXME: free data structures for pending operations
+    GNUNET_MQ_destroy (h->mq);
+    h->mq = NULL;
+  }
+  GNUNET_free (h);
+}
+
+
+/**
+ * Message sent notification.
+ *
+ * Remove invalidated envelope pointer.
+ */
+static void
+message_sent (void *cls)
+{
+  struct GNUNET_PSYCSTORE_OperationHandle *op = cls;
+  op->env = NULL;
+}
+
+
+/**
+ * Create a new operation.
+ */
+static struct GNUNET_PSYCSTORE_OperationHandle *
+op_create (struct GNUNET_PSYCSTORE_Handle *h,
+           struct GNUNET_OP_Handle *hop,
+           GNUNET_PSYCSTORE_ResultCallback result_cb,
+           void *cls)
+{
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = GNUNET_malloc (sizeof (*op));
+  op->h = h;
+  op->op_id = GNUNET_OP_add (hop,
+                             (GNUNET_ResultCallback) result_cb,
+                             cls, op);
+  return op;
+}
+
+
+/**
+ * Send a message associated with an operation.
+ *
+ * @param h
+ *        PSYCstore handle.
+ * @param op
+ *        Operation handle.
+ * @param env
+ *        Message envelope to send.
+ * @param[out] op_id
+ *        Operation ID to write in network byte order. NULL if not needed.
+ *
+ * @return Operation handle.
+ *
+ */
+static struct GNUNET_PSYCSTORE_OperationHandle *
+op_send (struct GNUNET_PSYCSTORE_Handle *h,
+         struct GNUNET_PSYCSTORE_OperationHandle *op,
+         struct GNUNET_MQ_Envelope *env,
+         uint64_t *op_id)
+{
+  op->env = env;
+  if (NULL != op_id)
+    *op_id = GNUNET_htonll (op->op_id);
+
+  GNUNET_MQ_notify_sent (env, message_sent, op);
+  GNUNET_MQ_send (h->mq, env);
+  return op;
+}
+
+
+/**
+ * Cancel a PSYCstore operation. Note that the operation MAY still
+ * be executed; this merely cancels the continuation; if the request
+ * was already transmitted, the service may still choose to complete
+ * the operation.
+ *
+ * @param op Operation to cancel.
+ *
+ * @return #GNUNET_YES if message was not sent yet and got discarded,
+ *         #GNUNET_NO  if it was already sent, and only the callbacks got cancelled.
+ */
+int
+GNUNET_PSYCSTORE_operation_cancel (struct GNUNET_PSYCSTORE_OperationHandle *op)
+{
+  struct GNUNET_PSYCSTORE_Handle *h = op->h;
+  int ret = GNUNET_NO;
+
+  if (NULL != op->env)
+  {
+    GNUNET_MQ_send_cancel (op->env);
+    ret = GNUNET_YES;
+  }
+
+  GNUNET_OP_remove (h->op, op->op_id);
+  GNUNET_free (op);
+
+  return ret;
+}
+
+
+/**
+ * Store join/leave events for a PSYC channel in order to be able to answer
+ * membership test queries later.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel where the event happened.
+ * @param slave_key
+ *        Public key of joining/leaving slave.
+ * @param did_join
+ *        #GNUNET_YES on join, #GNUNET_NO on part.
+ * @param announced_at
+ *        ID of the message that announced the membership change.
+ * @param effective_since
+ *        Message ID this membership change is in effect since.
+ *        For joins it is <= announced_at, for parts it is always 0.
+ * @param group_generation
+ *        In case of a part, the last group generation the slave has access to.
+ *        It has relevance when a larger message have fragments with different
+ *        group generations.
+ * @param result_cb
+ *        Callback to call with the result of the storage operation.
+ * @param cls
+ *        Closure for the callback.
+ *
+ * @return Operation handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_membership_store (struct GNUNET_PSYCSTORE_Handle *h,
+                                   const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                                   const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
+                                   int did_join,
+                                   uint64_t announced_at,
+                                   uint64_t effective_since,
+                                   uint64_t group_generation,
+                                   GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                   void *cls)
+{
+  GNUNET_assert (NULL != h);
+  GNUNET_assert (NULL != channel_key);
+  GNUNET_assert (NULL != slave_key);
+  GNUNET_assert (GNUNET_YES == did_join || GNUNET_NO == did_join);
+  GNUNET_assert (did_join
+                 ? effective_since <= announced_at
+                 : effective_since == 0);
+
+  struct MembershipStoreRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_MEMBERSHIP_STORE);
+  req->channel_key = *channel_key;
+  req->slave_key = *slave_key;
+  req->did_join = did_join;
+  req->announced_at = GNUNET_htonll (announced_at);
+  req->effective_since = GNUNET_htonll (effective_since);
+  req->group_generation = GNUNET_htonll (group_generation);
+
+  return
+    op_send (h, op_create (h, h->op, result_cb, cls),
+             env, &req->op_id);
+}
+
+
+/**
+ * Test if a member was admitted to the channel at the given message ID.
+ *
+ * This is useful when relaying and replaying messages to check if a particular
+ * slave has access to the message fragment with a given group generation.  It
+ * is also used when handling join requests to determine whether the slave is
+ * currently admitted to the channel.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param slave_key
+ *        Public key of slave whose membership to check.
+ * @param message_id
+ *        Message ID for which to do the membership test.
+ * @param group_generation
+ *        Group generation of the fragment of the message to test.
+ *        It has relevance if the message consists of multiple fragments with
+ *        different group generations.
+ * @param result_cb
+ *        Callback to call with the test result.
+ * @param cls
+ *        Closure for the callback.
+ *
+ * @return Operation handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_membership_test (struct GNUNET_PSYCSTORE_Handle *h,
+                                  const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                                  const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
+                                  uint64_t message_id,
+                                  uint64_t group_generation,
+                                  GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                  void *cls)
+{
+  struct MembershipTestRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_MEMBERSHIP_TEST);
+  req->channel_key = *channel_key;
+  req->slave_key = *slave_key;
+  req->message_id = GNUNET_htonll (message_id);
+  req->group_generation = GNUNET_htonll (group_generation);
+
+  return
+    op_send (h, op_create (h, h->op, result_cb, cls),
+             env, &req->op_id);
+}
+
+
+/**
+ * Store a message fragment sent to a channel.
+ *
+ * @param h Handle for the PSYCstore.
+ * @param channel_key The channel the message belongs to.
+ * @param message Message to store.
+ * @param psycstore_flags Flags indicating whether the PSYC message contains
+ *        state modifiers.
+ * @param result_cb Callback to call with the result of the operation.
+ * @param cls Closure for the callback.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_fragment_store (struct GNUNET_PSYCSTORE_Handle *h,
+                                 const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                                 const struct GNUNET_MULTICAST_MessageHeader *msg,
+                                 enum GNUNET_PSYCSTORE_MessageFlags psycstore_flags,
+                                 GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                 void *cls)
+{
+  uint16_t size = ntohs (msg->header.size);
+  struct FragmentStoreRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg_extra (req, size,
+                               GNUNET_MESSAGE_TYPE_PSYCSTORE_FRAGMENT_STORE);
+  req->channel_key = *channel_key;
+  req->psycstore_flags = htonl (psycstore_flags);
+  GNUNET_memcpy (&req[1], msg, size);
+
+  return
+    op_send (h, op_create (h, h->op, result_cb, cls),
+             env, &req->op_id);
+}
+
+
+/**
+ * Retrieve message fragments by fragment ID range.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param slave_key
+ *        The slave requesting the fragment.  If not NULL, a membership test is
+ *        performed first and the fragment is only returned if the slave has
+ *        access to it.
+ * @param first_fragment_id
+ *        First fragment ID to retrieve.
+ *        Use 0 to get the latest message fragment.
+ * @param last_fragment_id
+ *        Last consecutive fragment ID to retrieve.
+ *        Use 0 to get the latest message fragment.
+ * @param fragment_limit
+ *        Maximum number of fragments to retrieve.
+ * @param fragment_cb
+ *        Callback to call with the retrieved fragments.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_fragment_get (struct GNUNET_PSYCSTORE_Handle *h,
+                               const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                               const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
+                               uint64_t first_fragment_id,
+                               uint64_t last_fragment_id,
+                               GNUNET_PSYCSTORE_FragmentCallback fragment_cb,
+                               GNUNET_PSYCSTORE_ResultCallback result_cb,
+                               void *cls)
+{
+  struct FragmentGetRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_FRAGMENT_GET);
+  req->channel_key = *channel_key;
+  req->first_fragment_id = GNUNET_htonll (first_fragment_id);
+  req->last_fragment_id = GNUNET_htonll (last_fragment_id);
+  if (NULL != slave_key)
+  {
+    req->slave_key = *slave_key;
+    req->do_membership_test = GNUNET_YES;
+  }
+
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->fragment_cb = fragment_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
+}
+
+
+/**
+ * Retrieve latest message fragments.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param slave_key
+ *        The slave requesting the fragment.  If not NULL, a membership test is
+ *        performed first and the fragment is only returned if the slave has
+ *        access to it.
+ * @param first_fragment_id
+ *        First fragment ID to retrieve.
+ *        Use 0 to get the latest message fragment.
+ * @param last_fragment_id
+ *        Last consecutive fragment ID to retrieve.
+ *        Use 0 to get the latest message fragment.
+ * @param fragment_limit
+ *        Maximum number of fragments to retrieve.
+ * @param fragment_cb
+ *        Callback to call with the retrieved fragments.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_fragment_get_latest (struct GNUNET_PSYCSTORE_Handle *h,
+                                      const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                                      const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
+                                      uint64_t fragment_limit,
+                                      GNUNET_PSYCSTORE_FragmentCallback fragment_cb,
+                                      GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                      void *cls)
+{
+  struct FragmentGetRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_FRAGMENT_GET);
+  req->channel_key = *channel_key;
+  req->fragment_limit = GNUNET_ntohll (fragment_limit);
+  if (NULL != slave_key)
+  {
+    req->slave_key = *slave_key;
+    req->do_membership_test = GNUNET_YES;
+  }
+
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->fragment_cb = fragment_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
+}
+
+
+/**
+ * Retrieve all fragments of messages in a message ID range.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param slave_key
+ *        The slave requesting the message.
+ *        If not NULL, a membership test is performed first
+ *        and the message is only returned if the slave has access to it.
+ * @param first_message_id
+ *        First message ID to retrieve.
+ * @param last_message_id
+ *        Last consecutive message ID to retrieve.
+ * @param fragment_limit
+ *        Maximum number of fragments to retrieve.
+ * @param method_prefix
+ *        Retrieve only messages with a matching method prefix.
+ * @todo Implement method_prefix query.
+ * @param fragment_cb
+ *        Callback to call with the retrieved fragments.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_message_get (struct GNUNET_PSYCSTORE_Handle *h,
+                              const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                              const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
+                              uint64_t first_message_id,
+                              uint64_t last_message_id,
+                              uint64_t fragment_limit,
+                              const char *method_prefix,
+                              GNUNET_PSYCSTORE_FragmentCallback fragment_cb,
+                              GNUNET_PSYCSTORE_ResultCallback result_cb,
+                              void *cls)
+{
+  struct MessageGetRequest *req;
+  if (NULL == method_prefix)
+    method_prefix = "";
+  uint16_t method_size = strnlen (method_prefix,
+                                  GNUNET_MAX_MESSAGE_SIZE
+                                  - sizeof (*req)) + 1;
+
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg_extra (req, method_size,
+                               GNUNET_MESSAGE_TYPE_PSYCSTORE_MESSAGE_GET);
+  req->channel_key = *channel_key;
+  req->first_message_id = GNUNET_htonll (first_message_id);
+  req->last_message_id = GNUNET_htonll (last_message_id);
+  req->fragment_limit = GNUNET_htonll (fragment_limit);
+  if (NULL != slave_key)
+  {
+    req->slave_key = *slave_key;
+    req->do_membership_test = GNUNET_YES;
+  }
+  GNUNET_memcpy (&req[1], method_prefix, method_size);
+  ((char *) &req[1])[method_size - 1] = '\0';
+
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->fragment_cb = fragment_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
+}
+
+
+/**
+ * Retrieve all fragments of the latest messages.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param slave_key
+ *        The slave requesting the message.
+ *        If not NULL, a membership test is performed first
+ *        and the message is only returned if the slave has access to it.
+ * @param message_limit
+ *        Maximum number of messages to retrieve.
+ * @param method_prefix
+ *        Retrieve only messages with a matching method prefix.
+ * @todo Implement method_prefix query.
+ * @param fragment_cb
+ *        Callback to call with the retrieved fragments.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_message_get_latest (struct GNUNET_PSYCSTORE_Handle *h,
+                                     const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                                     const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
+                                     uint64_t message_limit,
+                                     const char *method_prefix,
+                                     GNUNET_PSYCSTORE_FragmentCallback fragment_cb,
+                                     GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                     void *cls)
+{
+  struct MessageGetRequest *req;
+
+  if (NULL == method_prefix)
+    method_prefix = "";
+  uint16_t method_size = strnlen (method_prefix,
+                                  GNUNET_MAX_MESSAGE_SIZE
+                                  - sizeof (*req)) + 1;
+  GNUNET_assert ('\0' == method_prefix[method_size - 1]);
+
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg_extra (req, method_size,
+                               GNUNET_MESSAGE_TYPE_PSYCSTORE_MESSAGE_GET);
+  req->channel_key = *channel_key;
+  req->message_limit = GNUNET_ntohll (message_limit);
+  if (NULL != slave_key)
+  {
+    req->slave_key = *slave_key;
+    req->do_membership_test = GNUNET_YES;
+  }
+  GNUNET_memcpy (&req[1], method_prefix, method_size);
+
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->fragment_cb = fragment_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
+}
+
+
+/**
+ * Retrieve a fragment of message specified by its message ID and fragment
+ * offset.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param slave_key
+ *        The slave requesting the message fragment.  If not NULL, a membership
+ *        test is performed first and the message fragment is only returned
+ *        if the slave has access to it.
+ * @param message_id
+ *        Message ID to retrieve.  Use 0 to get the latest message.
+ * @param fragment_offset
+ *        Offset of the fragment to retrieve.
+ * @param fragment_cb
+ *        Callback to call with the retrieved fragments.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_message_get_fragment (struct GNUNET_PSYCSTORE_Handle *h,
+                                       const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                                       const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
+                                       uint64_t message_id,
+                                       uint64_t fragment_offset,
+                                       GNUNET_PSYCSTORE_FragmentCallback fragment_cb,
+                                       GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                       void *cls)
+{
+  struct MessageGetFragmentRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_MESSAGE_GET_FRAGMENT);
+
+  req->channel_key = *channel_key;
+  req->message_id = GNUNET_htonll (message_id);
+  req->fragment_offset = GNUNET_htonll (fragment_offset);
+  if (NULL != slave_key)
+  {
+    req->slave_key = *slave_key;
+    req->do_membership_test = GNUNET_YES;
+  }
+
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->fragment_cb = fragment_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
+}
+
+
+/**
+ * Retrieve latest values of counters for a channel master.
+ *
+ * The current value of counters are needed when a channel master is restarted,
+ * so that it can continue incrementing the counters from their last value.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        Public key that identifies the channel.
+ * @param ccb
+ *        Callback to call with the result.
+ * @param ccb_cls
+ *        Closure for the @a ccb callback.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_counters_get (struct GNUNET_PSYCSTORE_Handle *h,
+                               struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                               GNUNET_PSYCSTORE_CountersCallback counters_cb,
+                               void *cls)
+{
+  struct OperationRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_COUNTERS_GET);
+  req->channel_key = *channel_key;
+
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, NULL, NULL);
+  op->counters_cb = counters_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
+}
+
+
+/**
+ * Apply modifiers of a message to the current channel state.
+ *
+ * An error is returned if there are missing messages containing state
+ * operations before the current one.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param message_id
+ *        ID of the message that contains the @a modifiers.
+ * @param state_delta
+ *        Value of the _state_delta PSYC header variable of the message.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for @a result_cb.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_state_modify (struct GNUNET_PSYCSTORE_Handle *h,
+                               const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                               uint64_t message_id,
+                               uint64_t state_delta,
+                               GNUNET_PSYCSTORE_ResultCallback result_cb,
+                               void *cls)
+{
+  struct StateModifyRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_MODIFY);
+  req->channel_key = *channel_key;
+  req->message_id = GNUNET_htonll (message_id);
+  req->state_delta = GNUNET_htonll (state_delta);
+
+  return op_send (h, op_create (h, h->op, result_cb, cls),
+                  env, &req->op_id);
+}
+
+
+struct StateSyncClosure
+{
+  GNUNET_PSYCSTORE_ResultCallback result_cb;
+  void *cls;
+  uint8_t last;
+};
+
+
+static void
+state_sync_result (void *cls, int64_t result,
+                   const char *err_msg, uint16_t err_msg_size)
+{
+  struct StateSyncClosure *ssc = cls;
+  if (GNUNET_OK != result || ssc->last)
+    ssc->result_cb (ssc->cls, result, err_msg, err_msg_size);
+  GNUNET_free (ssc);
+}
+
+
+/**
+ * Store synchronized state.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param max_state_message_id
+ *        ID of the last stateful message before @a state_hash_message_id.
+ * @param state_hash_message_id
+ *        ID of the message that contains the state_hash PSYC header variable.
+ * @param modifier_count
+ *        Number of elements in the @a modifiers array.
+ * @param modifiers
+ *        Full state to store.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callback.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_state_sync (struct GNUNET_PSYCSTORE_Handle *h,
+                             const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                             uint64_t max_state_message_id,
+                             uint64_t state_hash_message_id,
+                             size_t modifier_count,
+                             const struct GNUNET_PSYC_Modifier *modifiers,
+                             GNUNET_PSYCSTORE_ResultCallback result_cb,
+                             void *cls)
+{
+  struct GNUNET_PSYCSTORE_OperationHandle *op = NULL;
+  size_t i;
+
+  for (i = 0; i < modifier_count; i++) {
+    struct StateSyncRequest *req;
+    uint16_t name_size = strlen (modifiers[i].name) + 1;
+
+    struct GNUNET_MQ_Envelope *
+      env = GNUNET_MQ_msg_extra (req,
+                                 sizeof (*req) + name_size + modifiers[i].value_size,
+                                 GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_SYNC);
+
+    req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_SYNC);
+    req->header.size = htons (sizeof (*req) + name_size
+                              + modifiers[i].value_size);
+    req->channel_key = *channel_key;
+    req->max_state_message_id = GNUNET_htonll (max_state_message_id);
+    req->state_hash_message_id = GNUNET_htonll (state_hash_message_id);
+    req->name_size = htons (name_size);
+    req->flags
+      = (0 == i)
+      ? STATE_OP_FIRST
+      : (modifier_count - 1 == i)
+      ? STATE_OP_LAST
+      : 0;
+
+    GNUNET_memcpy (&req[1], modifiers[i].name, name_size);
+    GNUNET_memcpy ((char *) &req[1] + name_size, modifiers[i].value, modifiers[i].value_size);
+
+    struct StateSyncClosure *ssc = GNUNET_malloc (sizeof (*ssc));
+    ssc->last = (req->flags & STATE_OP_LAST);
+    ssc->result_cb = result_cb;
+    ssc->cls = cls;
+
+    op_send (h, op_create (h, h->op, state_sync_result, ssc),
+             env, &req->op_id);
+  }
+  // FIXME: only one operation is returned,
+  //        add pointers to other operations and make all cancellable.
+  return op;
+}
+
+
+/**
+ * Reset the state of a channel.
+ *
+ * Delete all state variables stored for the given channel.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callback.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_state_reset (struct GNUNET_PSYCSTORE_Handle *h,
+                              const struct GNUNET_CRYPTO_EddsaPublicKey
+                              *channel_key,
+                              GNUNET_PSYCSTORE_ResultCallback result_cb,
+                              void *cls)
+{
+  struct OperationRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_RESET);
+  req->channel_key = *channel_key;
+
+  return
+    op_send (h, op_create (h, h->op, result_cb, cls),
+             env, &req->op_id);
+}
+
+
+/**
+ * Update signed values of state variables in the state store.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param message_id
+ *        Message ID that contained the state @a hash.
+ * @param hash
+ *        Hash of the serialized full state.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callback.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_state_hash_update (struct GNUNET_PSYCSTORE_Handle *h,
+                                    const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                                    uint64_t message_id,
+                                    const struct GNUNET_HashCode *hash,
+                                    GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                    void *cls)
+{
+  struct StateHashUpdateRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_HASH_UPDATE);
+  req->channel_key = *channel_key;
+  req->hash = *hash;
+
+  return
+    op_send (h, op_create (h, h->op, result_cb, cls),
+             env, &req->op_id);
+}
+
+
+/**
+ * Retrieve the best matching state variable.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param name
+ *        Name of variable to match, the returned variable might be less specific.
+ * @param state_cb
+ *        Callback to return the matching state variable.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_state_get (struct GNUNET_PSYCSTORE_Handle *h,
+                            const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                            const char *name,
+                            GNUNET_PSYCSTORE_StateCallback state_cb,
+                            GNUNET_PSYCSTORE_ResultCallback result_cb,
+                            void *cls)
+{
+  size_t name_size = strlen (name) + 1;
+  struct OperationRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg_extra (req, name_size,
+                               GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_GET);
+  req->channel_key = *channel_key;
+  GNUNET_memcpy (&req[1], name, name_size);
+
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->state_cb = state_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
+}
+
+
+/**
+ * Retrieve all state variables for a channel with the given prefix.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param name_prefix
+ *        Prefix of state variable names to match.
+ * @param state_cb
+ *        Callback to return matching state variables.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_state_get_prefix (struct GNUNET_PSYCSTORE_Handle *h,
+                                   const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                                   const char *name_prefix,
+                                   GNUNET_PSYCSTORE_StateCallback state_cb,
+                                   GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                   void *cls)
+{
+  size_t name_size = strlen (name_prefix) + 1;
+  struct OperationRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg_extra (req, name_size,
+                               GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_GET_PREFIX);
+  req->channel_key = *channel_key;
+  GNUNET_memcpy (&req[1], name_prefix, name_size);
+
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->state_cb = state_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
+}
+
+/* end of psycstore_api.c */