1 files changed, 988 insertions, 0 deletions

diff --git a/src/service/core/gnunet-service-core.c b/src/service/core/gnunet-service-core.c
new file mode 100644
index 000000000..e387fecc9
--- /dev/null
+++ b/src/service/core/gnunet-service-core.c
@@ -0,0 +1,988 @@
+/*
+     This file is part of GNUnet.
+     Copyright (C) 2009, 2010, 2011, 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 core/gnunet-service-core.c
+ * @brief high-level P2P messaging
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <gcrypt.h>
+#include "gnunet_util_lib.h"
+#include "gnunet-service-core.h"
+#include "gnunet-service-core_kx.h"
+#include "gnunet-service-core_sessions.h"
+#include "gnunet-service-core_typemap.h"
+#include "gnunet_constants.h"
+
+/**
+ * How many messages do we queue up at most for any client? This can
+ * cause messages to be dropped if clients do not process them fast
+ * enough!  Note that this is a soft limit; we try
+ * to keep a few larger messages above the limit.
+ */
+#define SOFT_MAX_QUEUE 128
+
+/**
+ * How many messages do we queue up at most for any client? This can
+ * cause messages to be dropped if clients do not process them fast
+ * enough!  Note that this is the hard limit.
+ */
+#define HARD_MAX_QUEUE 256
+
+
+/**
+ * Data structure for each client connected to the CORE service.
+ */
+struct GSC_Client
+{
+  /**
+   * Clients are kept in a linked list.
+   */
+  struct GSC_Client *next;
+
+  /**
+   * Clients are kept in a linked list.
+   */
+  struct GSC_Client *prev;
+
+  /**
+   * Handle for the client with the server API.
+   */
+  struct GNUNET_SERVICE_Client *client;
+
+  /**
+   * Message queue to talk to @e client.
+   */
+  struct GNUNET_MQ_Handle *mq;
+
+  /**
+   * Array of the types of messages this peer cares
+   * about (with @e tcnt entries).  Allocated as part
+   * of this client struct, do not free!
+   */
+  uint16_t *types;
+
+  /**
+   * Map of peer identities to active transmission requests of this
+   * client to the peer (of type `struct GSC_ClientActiveRequest`).
+   */
+  struct GNUNET_CONTAINER_MultiPeerMap *requests;
+
+  /**
+   * Map containing all peers that this client knows we're connected to.
+   */
+  struct GNUNET_CONTAINER_MultiPeerMap *connectmap;
+
+  /**
+   * Options for messages this client cares about,
+   * see GNUNET_CORE_OPTION_ values.
+   */
+  uint32_t options;
+
+  /**
+   * Have we gotten the #GNUNET_MESSAGE_TYPE_CORE_INIT message
+   * from this client already?
+   */
+  int got_init;
+
+  /**
+   * Number of types of incoming messages this client
+   * specifically cares about.  Size of the @e types array.
+   */
+  unsigned int tcnt;
+};
+
+
+/**
+ * Our identity.
+ */
+struct GNUNET_PeerIdentity GSC_my_identity;
+
+/**
+ * Our configuration.
+ */
+const struct GNUNET_CONFIGURATION_Handle *GSC_cfg;
+
+/**
+ * For creating statistics.
+ */
+struct GNUNET_STATISTICS_Handle *GSC_stats;
+
+/**
+ * Big "or" of all client options.
+ */
+static uint32_t all_client_options;
+
+/**
+ * Head of linked list of our clients.
+ */
+static struct GSC_Client *client_head;
+
+/**
+ * Tail of linked list of our clients.
+ */
+static struct GSC_Client *client_tail;
+
+
+/**
+ * Test if the client is interested in messages of the given type.
+ *
+ * @param type message type
+ * @param c client to test
+ * @return #GNUNET_YES if @a c is interested, #GNUNET_NO if not.
+ */
+static int
+type_match (uint16_t type, struct GSC_Client *c)
+{
+  if ((0 == c->tcnt) && (0 != c->options))
+    return GNUNET_YES; /* peer without handlers and inbound/outbond
+                                   callbacks matches ALL */
+  if (NULL == c->types)
+    return GNUNET_NO;
+  for (unsigned int i = 0; i < c->tcnt; i++)
+    if (type == c->types[i])
+      return GNUNET_YES;
+  return GNUNET_NO;
+}
+
+
+/**
+ * Check #GNUNET_MESSAGE_TYPE_CORE_INIT request.
+ *
+ * @param cls client that sent #GNUNET_MESSAGE_TYPE_CORE_INIT
+ * @param im the `struct InitMessage`
+ * @return #GNUNET_OK if @a im is well-formed
+ */
+static int
+check_client_init (void *cls, const struct InitMessage *im)
+{
+  return GNUNET_OK;
+}
+
+
+/**
+ * Handle #GNUNET_MESSAGE_TYPE_CORE_INIT request.
+ *
+ * @param cls client that sent #GNUNET_MESSAGE_TYPE_CORE_INIT
+ * @param im the `struct InitMessage`
+ */
+static void
+handle_client_init (void *cls, const struct InitMessage *im)
+{
+  struct GSC_Client *c = cls;
+  struct GNUNET_MQ_Envelope *env;
+  struct InitReplyMessage *irm;
+  uint16_t msize;
+  const uint16_t *types;
+
+  /* check that we don't have an entry already */
+  msize = ntohs (im->header.size) - sizeof(struct InitMessage);
+  types = (const uint16_t *) &im[1];
+  c->tcnt = msize / sizeof(uint16_t);
+  c->options = ntohl (im->options);
+  c->got_init = GNUNET_YES;
+  all_client_options |= c->options;
+  c->types = GNUNET_malloc (msize);
+  GNUNET_assert (GNUNET_YES ==
+                 GNUNET_CONTAINER_multipeermap_put (
+                   c->connectmap,
+                   &GSC_my_identity,
+                   NULL,
+                   GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
+  for (unsigned int i = 0; i < c->tcnt; i++)
+    c->types[i] = ntohs (types[i]);
+  GSC_TYPEMAP_add (c->types, c->tcnt);
+  GNUNET_log (
+    GNUNET_ERROR_TYPE_DEBUG,
+    "Client connecting to core service is interested in %u message types\n",
+    (unsigned int) c->tcnt);
+  /* send init reply message */
+  env = GNUNET_MQ_msg (irm, GNUNET_MESSAGE_TYPE_CORE_INIT_REPLY);
+  irm->reserved = htonl (0);
+  irm->my_identity = GSC_my_identity;
+  GNUNET_MQ_send (c->mq, env);
+  GSC_SESSIONS_notify_client_about_sessions (c);
+  GNUNET_SERVICE_client_continue (c->client);
+}
+
+
+/**
+ * We will never be ready to transmit the given message in (disconnect
+ * or invalid request).  Frees resources associated with @a car.  We
+ * don't explicitly tell the client, it'll learn with the disconnect
+ * (or violated the protocol).
+ *
+ * @param car request that now permanently failed; the
+ *        responsibility for the handle is now returned
+ *        to CLIENTS (SESSIONS is done with it).
+ * @param drop_client #GNUNET_YES if the client violated the protocol
+ *        and we should thus drop the connection
+ */
+void
+GSC_CLIENTS_reject_request (struct GSC_ClientActiveRequest *car,
+                            int drop_client)
+{
+  GNUNET_assert (
+    GNUNET_YES ==
+    GNUNET_CONTAINER_multipeermap_remove (car->client_handle->requests,
+                                          &car->target,
+                                          car));
+  if (GNUNET_YES == drop_client)
+    GNUNET_SERVICE_client_drop (car->client_handle->client);
+  GNUNET_free (car);
+}
+
+
+/**
+ * Tell a client that we are ready to receive the message.
+ *
+ * @param car request that is now ready; the responsibility
+ *        for the handle remains shared between CLIENTS
+ *        and SESSIONS after this call.
+ */
+void
+GSC_CLIENTS_solicit_request (struct GSC_ClientActiveRequest *car)
+{
+  struct GSC_Client *c;
+  struct GNUNET_MQ_Envelope *env;
+  struct SendMessageReady *smr;
+  struct GNUNET_TIME_Relative delay;
+  struct GNUNET_TIME_Relative left;
+
+  c = car->client_handle;
+  if (GNUNET_YES !=
+      GNUNET_CONTAINER_multipeermap_contains (c->connectmap, &car->target))
+  {
+    /* connection has gone down since, drop request */
+    GNUNET_assert (0 !=
+                   GNUNET_memcmp (&car->target,
+                                  &GSC_my_identity));
+    GSC_SESSIONS_dequeue_request (car);
+    GSC_CLIENTS_reject_request (car, GNUNET_NO);
+    return;
+  }
+  delay = GNUNET_TIME_absolute_get_duration (car->received_time);
+  left = GNUNET_TIME_absolute_get_duration (car->deadline);
+  if (delay.rel_value_us > GNUNET_CONSTANTS_LATENCY_WARN.rel_value_us)
+    GNUNET_log (
+      GNUNET_ERROR_TYPE_WARNING,
+      "Client waited %s for permission to transmit to `%s'%s (priority %u)\n",
+      GNUNET_STRINGS_relative_time_to_string (delay, GNUNET_YES),
+      GNUNET_i2s (&car->target),
+      (0 == left.rel_value_us) ? " (past deadline)" : "",
+      car->priority);
+  env = GNUNET_MQ_msg (smr, GNUNET_MESSAGE_TYPE_CORE_SEND_READY);
+  smr->size = htons (car->msize);
+  smr->smr_id = car->smr_id;
+  smr->peer = car->target;
+  GNUNET_MQ_send (c->mq, env);
+}
+
+
+/**
+ * Handle #GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST message.
+ *
+ * @param cls client that sent a #GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST
+ * @param req the `struct SendMessageRequest`
+ */
+static void
+handle_client_send_request (void *cls, const struct SendMessageRequest *req)
+{
+  struct GSC_Client *c = cls;
+  struct GSC_ClientActiveRequest *car;
+  int is_loopback;
+
+  if (NULL == c->requests)
+    c->requests = GNUNET_CONTAINER_multipeermap_create (16, GNUNET_NO);
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Client asked for transmission to `%s'\n",
+              GNUNET_i2s (&req->peer));
+  is_loopback = (0 == GNUNET_memcmp (&req->peer,
+                                     &GSC_my_identity));
+  if ((! is_loopback) &&
+      (GNUNET_YES !=
+       GNUNET_CONTAINER_multipeermap_contains (c->connectmap, &req->peer)))
+  {
+    /* neighbour must have disconnected since request was issued,
+     * ignore (client will realize it once it processes the
+     * disconnect notification) */
+    GNUNET_STATISTICS_update (GSC_stats,
+                              gettext_noop (
+                                "# send requests dropped (disconnected)"),
+                              1,
+                              GNUNET_NO);
+    GNUNET_SERVICE_client_continue (c->client);
+    return;
+  }
+
+  car = GNUNET_CONTAINER_multipeermap_get (c->requests, &req->peer);
+  if (NULL == car)
+  {
+    /* create new entry */
+    car = GNUNET_new (struct GSC_ClientActiveRequest);
+    GNUNET_assert (GNUNET_OK ==
+                   GNUNET_CONTAINER_multipeermap_put (
+                     c->requests,
+                     &req->peer,
+                     car,
+                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST));
+    car->client_handle = c;
+  }
+  else
+  {
+    /* dequeue and recycle memory from pending request, there can only
+       be at most one per client and peer */
+    GNUNET_STATISTICS_update (GSC_stats,
+                              gettext_noop (
+                                "# dequeuing CAR (duplicate request)"),
+                              1,
+                              GNUNET_NO);
+    GSC_SESSIONS_dequeue_request (car);
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Transmission request to `%s' was a duplicate!\n",
+                GNUNET_i2s (&req->peer));
+  }
+  car->target = req->peer;
+  car->received_time = GNUNET_TIME_absolute_get ();
+  car->deadline = GNUNET_TIME_absolute_ntoh (req->deadline);
+  car->priority = (enum GNUNET_MQ_PriorityPreferences) ntohl (req->priority);
+  car->msize = ntohs (req->size);
+  car->smr_id = req->smr_id;
+  car->was_solicited = GNUNET_NO;
+  GNUNET_SERVICE_client_continue (c->client);
+  if (is_loopback)
+  {
+    /* loopback, satisfy immediately */
+    GSC_CLIENTS_solicit_request (car);
+    return;
+  }
+  GSC_SESSIONS_queue_request (car);
+}
+
+
+/**
+ * Closure for the #client_tokenizer_callback().
+ */
+struct TokenizerContext
+{
+  /**
+   * Active request handle for the message.
+   */
+  struct GSC_ClientActiveRequest *car;
+
+  /**
+   * How important is this message.
+   */
+  enum GNUNET_MQ_PriorityPreferences priority;
+};
+
+
+/**
+ * Functions with this signature are called whenever a complete
+ * message is received by the tokenizer.  Used by
+ * #handle_client_send() for dispatching messages from clients to
+ * either the SESSION subsystem or other CLIENT (for loopback).
+ *
+ * @param cls reservation request (`struct TokenizerContext`)
+ * @param message the actual message
+ * @return #GNUNET_OK on success,
+ *    #GNUNET_NO to stop further processing (no error)
+ *    #GNUNET_SYSERR to stop further processing with error
+ */
+static int
+tokenized_cb (void *cls, const struct GNUNET_MessageHeader *message)
+{
+  struct TokenizerContext *tc = cls;
+  struct GSC_ClientActiveRequest *car = tc->car;
+  char buf[92];
+
+  GNUNET_snprintf (buf,
+                   sizeof(buf),
+                   gettext_noop ("# bytes of messages of type %u received"),
+                   (unsigned int) ntohs (message->type));
+  GNUNET_STATISTICS_update (GSC_stats, buf, ntohs (message->size), GNUNET_NO);
+  if (0 == GNUNET_memcmp (&car->target,
+                          &GSC_my_identity))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Delivering message of type %u to myself\n",
+                ntohs (message->type));
+    GSC_CLIENTS_deliver_message (&GSC_my_identity,
+                                 message,
+                                 ntohs (message->size),
+                                 GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND);
+    GSC_CLIENTS_deliver_message (&GSC_my_identity,
+                                 message,
+                                 sizeof(struct GNUNET_MessageHeader),
+                                 GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND);
+    GSC_CLIENTS_deliver_message (&GSC_my_identity,
+                                 message,
+                                 ntohs (message->size),
+                                 GNUNET_CORE_OPTION_SEND_FULL_INBOUND);
+    GSC_CLIENTS_deliver_message (&GSC_my_identity,
+                                 message,
+                                 sizeof(struct GNUNET_MessageHeader),
+                                 GNUNET_CORE_OPTION_SEND_HDR_INBOUND);
+  }
+  else
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Delivering message of type %u and size %u to %s\n",
+                ntohs (message->type),
+                ntohs (message->size),
+                GNUNET_i2s (&car->target));
+    GSC_CLIENTS_deliver_message (&car->target,
+                                 message,
+                                 ntohs (message->size),
+                                 GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND);
+    GSC_CLIENTS_deliver_message (&car->target,
+                                 message,
+                                 sizeof(struct GNUNET_MessageHeader),
+                                 GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND);
+    GSC_SESSIONS_transmit (car, message, tc->priority);
+  }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Check #GNUNET_MESSAGE_TYPE_CORE_SEND request.
+ *
+ * @param cls the `struct GSC_Client`
+ * @param sm the `struct SendMessage`
+ * @return #GNUNET_OK if @a sm is well-formed
+ */
+static int
+check_client_send (void *cls, const struct SendMessage *sm)
+{
+  return GNUNET_OK;
+}
+
+
+/**
+ * Handle #GNUNET_MESSAGE_TYPE_CORE_SEND request.
+ *
+ * @param cls the `struct GSC_Client`
+ * @param sm the `struct SendMessage`
+ */
+static void
+handle_client_send (void *cls, const struct SendMessage *sm)
+{
+  struct GSC_Client *c = cls;
+  struct TokenizerContext tc;
+  uint16_t msize;
+  struct GNUNET_TIME_Relative delay;
+  struct GNUNET_MessageStreamTokenizer *mst;
+
+  msize = ntohs (sm->header.size) - sizeof(struct SendMessage);
+  tc.car = GNUNET_CONTAINER_multipeermap_get (c->requests, &sm->peer);
+  if (NULL == tc.car)
+  {
+    /* Must have been that we first approved the request, then got disconnected
+     * (which triggered removal of the 'car') and now the client gives us a message
+     * just *before* the client learns about the disconnect.  Theoretically, we
+     * might also now be *again* connected.  So this can happen (but should be
+     * rare).  If it does happen, the message is discarded. */GNUNET_STATISTICS_update (GSC_stats,
+                              gettext_noop (
+                                "# messages discarded (session disconnected)"),
+                              1,
+                              GNUNET_NO);
+    GNUNET_SERVICE_client_continue (c->client);
+    return;
+  }
+  delay = GNUNET_TIME_absolute_get_duration (tc.car->received_time);
+  tc.priority = (enum GNUNET_MQ_PriorityPreferences) ntohl (sm->priority);
+  if (delay.rel_value_us > GNUNET_CONSTANTS_LATENCY_WARN.rel_value_us)
+    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                "Client waited %s for transmission of %u bytes to `%s'\n",
+                GNUNET_STRINGS_relative_time_to_string (delay, GNUNET_YES),
+                msize,
+                GNUNET_i2s (&sm->peer));
+  else
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Client waited %s for transmission of %u bytes to `%s'\n",
+                GNUNET_STRINGS_relative_time_to_string (delay, GNUNET_YES),
+                msize,
+                GNUNET_i2s (&sm->peer));
+
+  GNUNET_assert (
+    GNUNET_YES ==
+    GNUNET_CONTAINER_multipeermap_remove (c->requests, &sm->peer, tc.car));
+  mst = GNUNET_MST_create (&tokenized_cb, &tc);
+  GNUNET_MST_from_buffer (mst,
+                          (const char *) &sm[1],
+                          msize,
+                          GNUNET_YES,
+                          GNUNET_NO);
+  GNUNET_MST_destroy (mst);
+  GSC_SESSIONS_dequeue_request (tc.car);
+  GNUNET_free (tc.car);
+  GNUNET_SERVICE_client_continue (c->client);
+}
+
+
+/**
+ * Free client request records.
+ *
+ * @param cls NULL
+ * @param key identity of peer for which this is an active request
+ * @param value the `struct GSC_ClientActiveRequest` to free
+ * @return #GNUNET_YES (continue iteration)
+ */
+static int
+destroy_active_client_request (void *cls,
+                               const struct GNUNET_PeerIdentity *key,
+                               void *value)
+{
+  struct GSC_ClientActiveRequest *car = value;
+
+  GNUNET_assert (
+    GNUNET_YES ==
+    GNUNET_CONTAINER_multipeermap_remove (car->client_handle->requests,
+                                          &car->target,
+                                          car));
+  GSC_SESSIONS_dequeue_request (car);
+  GNUNET_free (car);
+  return GNUNET_YES;
+}
+
+
+/**
+ * A client connected, set up.
+ *
+ * @param cls closure
+ * @param client identification of the client
+ * @param mq message queue to talk to @a client
+ * @return our client handle
+ */
+static void *
+client_connect_cb (void *cls,
+                   struct GNUNET_SERVICE_Client *client,
+                   struct GNUNET_MQ_Handle *mq)
+{
+  struct GSC_Client *c;
+
+  c = GNUNET_new (struct GSC_Client);
+  c->client = client;
+  c->mq = mq;
+  c->connectmap = GNUNET_CONTAINER_multipeermap_create (16, GNUNET_NO);
+  GNUNET_CONTAINER_DLL_insert (client_head, client_tail, c);
+  return c;
+}
+
+
+/**
+ * A client disconnected, clean up.
+ *
+ * @param cls closure
+ * @param client identification of the client
+ * @param app_ctx our `struct GST_Client` for @a client
+ */
+static void
+client_disconnect_cb (void *cls,
+                      struct GNUNET_SERVICE_Client *client,
+                      void *app_ctx)
+{
+  struct GSC_Client *c = app_ctx;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Client %p has disconnected from core service.\n",
+              client);
+  GNUNET_CONTAINER_DLL_remove (client_head, client_tail, c);
+  if (NULL != c->requests)
+  {
+    GNUNET_CONTAINER_multipeermap_iterate (c->requests,
+                                           &destroy_active_client_request,
+                                           NULL);
+    GNUNET_CONTAINER_multipeermap_destroy (c->requests);
+  }
+  GNUNET_CONTAINER_multipeermap_destroy (c->connectmap);
+  c->connectmap = NULL;
+  if (NULL != c->types)
+  {
+    GSC_TYPEMAP_remove (c->types, c->tcnt);
+    GNUNET_free (c->types);
+  }
+  GNUNET_free (c);
+
+  /* recalculate 'all_client_options' */
+  all_client_options = 0;
+  for (c = client_head; NULL != c; c = c->next)
+    all_client_options |= c->options;
+}
+
+
+/**
+ * Notify a particular client about a change to existing connection to
+ * one of our neighbours (check if the client is interested).  Called
+ * from #GSC_SESSIONS_notify_client_about_sessions().
+ *
+ * @param client client to notify
+ * @param neighbour identity of the neighbour that changed status
+ * @param tmap_old previous type map for the neighbour, NULL for connect
+ * @param tmap_new updated type map for the neighbour, NULL for disconnect
+ */
+void
+GSC_CLIENTS_notify_client_about_neighbour (
+  struct GSC_Client *client,
+  const struct GNUNET_PeerIdentity *neighbour,
+  const struct GSC_TypeMap *tmap_old,
+  const struct GSC_TypeMap *tmap_new)
+{
+  struct GNUNET_MQ_Envelope *env;
+  int old_match;
+  int new_match;
+
+  if (GNUNET_YES != client->got_init)
+    return;
+  old_match = GSC_TYPEMAP_test_match (tmap_old, client->types, client->tcnt);
+  new_match = GSC_TYPEMAP_test_match (tmap_new, client->types, client->tcnt);
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Notifying client about neighbour %s (%d/%d)\n",
+              GNUNET_i2s (neighbour),
+              old_match,
+              new_match);
+  if (old_match == new_match)
+  {
+    GNUNET_assert (
+      old_match ==
+      GNUNET_CONTAINER_multipeermap_contains (client->connectmap, neighbour));
+    return;   /* no change */
+  }
+  if (GNUNET_NO == old_match)
+  {
+    struct ConnectNotifyMessage *cnm;
+
+    /* send connect */
+    GNUNET_assert (
+      GNUNET_NO ==
+      GNUNET_CONTAINER_multipeermap_contains (client->connectmap, neighbour));
+    GNUNET_assert (GNUNET_YES ==
+                   GNUNET_CONTAINER_multipeermap_put (
+                     client->connectmap,
+                     neighbour,
+                     NULL,
+                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
+    env = GNUNET_MQ_msg (cnm, GNUNET_MESSAGE_TYPE_CORE_NOTIFY_CONNECT);
+    cnm->reserved = htonl (0);
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Sending NOTIFY_CONNECT message about peer %s to client.\n",
+                GNUNET_i2s (neighbour));
+    cnm->peer = *neighbour;
+    GNUNET_MQ_send (client->mq, env);
+  }
+  else
+  {
+    struct DisconnectNotifyMessage *dcm;
+
+    /* send disconnect */
+    GNUNET_assert (
+      GNUNET_YES ==
+      GNUNET_CONTAINER_multipeermap_contains (client->connectmap, neighbour));
+    GNUNET_assert (GNUNET_YES ==
+                   GNUNET_CONTAINER_multipeermap_remove (client->connectmap,
+                                                         neighbour,
+                                                         NULL));
+    env = GNUNET_MQ_msg (dcm, GNUNET_MESSAGE_TYPE_CORE_NOTIFY_DISCONNECT);
+    dcm->reserved = htonl (0);
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Sending NOTIFY_DISCONNECT message about peer %s to client.\n",
+                GNUNET_i2s (neighbour));
+    dcm->peer = *neighbour;
+    GNUNET_MQ_send (client->mq, env);
+  }
+}
+
+
+/**
+ * Notify all clients about a change to existing session.
+ * Called from SESSIONS whenever there is a change in sessions
+ * or types processed by the respective peer.
+ *
+ * @param neighbour identity of the neighbour that changed status
+ * @param tmap_old previous type map for the neighbour, NULL for connect
+ * @param tmap_new updated type map for the neighbour, NULL for disconnect
+ */
+void
+GSC_CLIENTS_notify_clients_about_neighbour (
+  const struct GNUNET_PeerIdentity *neighbour,
+  const struct GSC_TypeMap *tmap_old,
+  const struct GSC_TypeMap *tmap_new)
+{
+  struct GSC_Client *c;
+
+  for (c = client_head; NULL != c; c = c->next)
+    GSC_CLIENTS_notify_client_about_neighbour (c,
+                                               neighbour,
+                                               tmap_old,
+                                               tmap_new);
+}
+
+
+/**
+ * Deliver P2P message to interested clients.  Caller must have checked
+ * that the sending peer actually lists the given message type as one
+ * of its types.
+ *
+ * @param sender peer who sent us the message
+ * @param msg the message
+ * @param msize number of bytes to transmit
+ * @param options options for checking which clients should
+ *        receive the message
+ */
+void
+GSC_CLIENTS_deliver_message (const struct GNUNET_PeerIdentity *sender,
+                             const struct GNUNET_MessageHeader *msg,
+                             uint16_t msize,
+                             uint32_t options)
+{
+  size_t size = msize + sizeof(struct NotifyTrafficMessage);
+
+  if (size >= GNUNET_MAX_MESSAGE_SIZE)
+  {
+    GNUNET_break (0);
+    return;
+  }
+  if (! ((0 != (all_client_options & options)) ||
+         (0 != (options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND))))
+    return; /* no client cares about this message notification */
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Core service passes message from `%s' of type %u to client.\n",
+              GNUNET_i2s (sender),
+              (unsigned int) ntohs (msg->type));
+  GSC_SESSIONS_add_to_typemap (sender, ntohs (msg->type));
+
+  for (struct GSC_Client *c = client_head; NULL != c; c = c->next)
+  {
+    struct GNUNET_MQ_Envelope *env;
+    struct NotifyTrafficMessage *ntm;
+    uint16_t mtype;
+    unsigned int qlen;
+    int tm;
+
+    tm = type_match (ntohs (msg->type), c);
+    if (! ((0 != (c->options & options)) ||
+           ((0 != (options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND)) &&
+            (GNUNET_YES == tm))))
+      continue;   /* neither options nor type match permit the message */
+    if ((0 != (options & GNUNET_CORE_OPTION_SEND_HDR_INBOUND)) &&
+        ((0 != (c->options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND)) ||
+         (GNUNET_YES == tm)))
+      continue;
+    if ((0 != (options & GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND)) &&
+        (0 != (c->options & GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND)))
+      continue;
+
+    /* Drop messages if:
+       1) We are above the hard limit, or
+       2) We are above the soft limit, and a coin toss limited
+          to the message size (giving larger messages a
+          proportionally higher chance of being queued) falls
+          below the threshold. The threshold is based on where
+          we are between the soft and the hard limit, scaled
+          to match the range of message sizes we usually encounter
+          (i.e. up to 32k); so a 64k message has a 50% chance of
+          being kept if we are just barely below the hard max,
+          and a 99% chance of being kept if we are at the soft max.
+       The reason is to make it more likely to drop control traffic
+       (ACK, queries) which may be cumulative or highly redundant,
+       and cheap to drop than data traffic.  */qlen = GNUNET_MQ_get_length (c->mq);
+    if ((qlen >= HARD_MAX_QUEUE) ||
+        ((qlen > SOFT_MAX_QUEUE) &&
+         ((GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
+                                     ntohs (msg->size))) <
+          (qlen - SOFT_MAX_QUEUE) * 0x8000
+          / (HARD_MAX_QUEUE - SOFT_MAX_QUEUE))))
+    {
+      char buf[1024];
+
+      GNUNET_log (
+        GNUNET_ERROR_TYPE_INFO | GNUNET_ERROR_TYPE_BULK,
+        "Dropping decrypted message of type %u as client is too busy (queue full)\n",
+        (unsigned int) ntohs (msg->type));
+      GNUNET_snprintf (buf,
+                       sizeof(buf),
+                       gettext_noop (
+                         "# messages of type %u discarded (client busy)"),
+                       (unsigned int) ntohs (msg->type));
+      GNUNET_STATISTICS_update (GSC_stats, buf, 1, GNUNET_NO);
+      continue;
+    }
+
+    GNUNET_log (
+      GNUNET_ERROR_TYPE_DEBUG,
+      "Sending %u message with %u bytes to client interested in messages of type %u.\n",
+      options,
+      ntohs (msg->size),
+      (unsigned int) ntohs (msg->type));
+
+    if (0 != (options & (GNUNET_CORE_OPTION_SEND_FULL_INBOUND
+                         | GNUNET_CORE_OPTION_SEND_HDR_INBOUND)))
+      mtype = GNUNET_MESSAGE_TYPE_CORE_NOTIFY_INBOUND;
+    else
+      mtype = GNUNET_MESSAGE_TYPE_CORE_NOTIFY_OUTBOUND;
+    env = GNUNET_MQ_msg_extra (ntm, msize, mtype);
+    ntm->peer = *sender;
+    GNUNET_memcpy (&ntm[1], msg, msize);
+
+    GNUNET_assert (
+      (0 == (c->options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND)) ||
+      (GNUNET_YES != tm) ||
+      (GNUNET_YES ==
+       GNUNET_CONTAINER_multipeermap_contains (c->connectmap, sender)));
+    GNUNET_MQ_send (c->mq, env);
+  }
+}
+
+
+/**
+ * Last task run during shutdown.  Disconnects us from
+ * the transport.
+ *
+ * @param cls NULL, unused
+ */
+static void
+shutdown_task (void *cls)
+{
+  struct GSC_Client *c;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Core service shutting down.\n");
+  while (NULL != (c = client_head))
+    GNUNET_SERVICE_client_drop (c->client);
+  GSC_SESSIONS_done ();
+  GSC_KX_done ();
+  GSC_TYPEMAP_done ();
+  if (NULL != GSC_stats)
+  {
+    GNUNET_STATISTICS_destroy (GSC_stats, GNUNET_NO);
+    GSC_stats = NULL;
+  }
+  GSC_cfg = NULL;
+}
+
+
+/**
+ * Handle #GNUNET_MESSAGE_TYPE_CORE_MONITOR_PEERS request.  For this
+ * request type, the client does not have to have transmitted an INIT
+ * request.  All current peers are returned, regardless of which
+ * message types they accept.
+ *
+ * @param cls client sending the iteration request
+ * @param message iteration request message
+ */
+static void
+handle_client_monitor_peers (void *cls,
+                             const struct GNUNET_MessageHeader *message)
+{
+  struct GSC_Client *c = cls;
+
+  GNUNET_SERVICE_client_continue (c->client);
+  GSC_KX_handle_client_monitor_peers (c->mq);
+}
+
+
+/**
+ * Initiate core service.
+ *
+ * @param cls closure
+ * @param c configuration to use
+ * @param service the initialized service
+ */
+static void
+run (void *cls,
+     const struct GNUNET_CONFIGURATION_Handle *c,
+     struct GNUNET_SERVICE_Handle *service)
+{
+  struct GNUNET_CRYPTO_EddsaPrivateKey pk;
+  char *keyfile;
+
+  GSC_cfg = c;
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_filename (GSC_cfg,
+                                               "PEER",
+                                               "PRIVATE_KEY",
+                                               &keyfile))
+  {
+    GNUNET_log (
+      GNUNET_ERROR_TYPE_ERROR,
+      _ ("Core service is lacking HOSTKEY configuration setting.  Exiting.\n"));
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  }
+  GSC_stats = GNUNET_STATISTICS_create ("core", GSC_cfg);
+  GNUNET_SCHEDULER_add_shutdown (&shutdown_task, NULL);
+  GNUNET_SERVICE_suspend (service);
+  GSC_TYPEMAP_init ();
+  if (GNUNET_SYSERR ==
+      GNUNET_CRYPTO_eddsa_key_from_file (keyfile,
+                                         GNUNET_YES,
+                                         &pk))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Failed to setup peer's private key\n");
+    GNUNET_SCHEDULER_shutdown ();
+    GNUNET_free (keyfile);
+    return;
+  }
+  GNUNET_free (keyfile);
+  if (GNUNET_OK != GSC_KX_init (&pk))
+  {
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  }
+  GSC_SESSIONS_init ();
+  GNUNET_SERVICE_resume (service);
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              _ ("Core service of `%s' ready.\n"),
+              GNUNET_i2s (&GSC_my_identity));
+}
+
+
+/**
+ * Define "main" method using service macro.
+ */
+GNUNET_SERVICE_MAIN (
+  "core",
+  GNUNET_SERVICE_OPTION_NONE,
+  &run,
+  &client_connect_cb,
+  &client_disconnect_cb,
+  NULL,
+  GNUNET_MQ_hd_var_size (client_init,
+                         GNUNET_MESSAGE_TYPE_CORE_INIT,
+                         struct InitMessage,
+                         NULL),
+  GNUNET_MQ_hd_fixed_size (client_monitor_peers,
+                           GNUNET_MESSAGE_TYPE_CORE_MONITOR_PEERS,
+                           struct GNUNET_MessageHeader,
+                           NULL),
+  GNUNET_MQ_hd_fixed_size (client_send_request,
+                           GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST,
+                           struct SendMessageRequest,
+                           NULL),
+  GNUNET_MQ_hd_var_size (client_send,
+                         GNUNET_MESSAGE_TYPE_CORE_SEND,
+                         struct SendMessage,
+                         NULL),
+  GNUNET_MQ_handler_end ());
+
+
+/* end of gnunet-service-core.c */