transport_api_core.c

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/*
     This file is part of GNUnet.
     Copyright (C) 2009-2013, 2016, 2018 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
 */
 
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_constants.h"
#include "gnunet_arm_service.h"
#include "gnunet_protocols.h"
#include "gnunet_transport_core_service.h"
#include "transport.h"
 
#define LOG(kind, ...) GNUNET_log_from (kind, "transport-api-core", __VA_ARGS__)
 
#define STARTING_NEIGHBOURS_SIZE 16
 
#define SEND_WINDOW_SIZE 4
 
 
struct Neighbour
{
  struct GNUNET_PeerIdentity id;
 
  struct GNUNET_TRANSPORT_CoreHandle *h;
 
  struct GNUNET_MQ_Handle *mq;
 
  struct GNUNET_MQ_Envelope *env;
 
  void *handlers_cls;
 
  unsigned int ready_window;
 
  int16_t awaiting_done;
 
  uint16_t env_size;
};
 
 
struct GNUNET_TRANSPORT_CoreHandle
{
  void *cls;
 
  struct GNUNET_MQ_MessageHandler *handlers;
 
  GNUNET_TRANSPORT_NotifyConnect nc_cb;
 
  GNUNET_TRANSPORT_NotifyDisconnect nd_cb;
 
  struct GNUNET_MQ_Handle *mq;
 
  const struct GNUNET_CONFIGURATION_Handle *cfg;
 
  struct GNUNET_CONTAINER_MultiPeerMap *neighbours;
 
  struct GNUNET_PeerIdentity self;
 
  struct GNUNET_SCHEDULER_Task *reconnect_task;
 
  struct GNUNET_TIME_Relative reconnect_delay;
 
  struct GNUNET_TIME_Absolute restarted_at;
 
  int check_self;
};
 
 
static void
disconnect_and_schedule_reconnect (struct GNUNET_TRANSPORT_CoreHandle *h);
 
 
static struct Neighbour *
neighbour_find (struct GNUNET_TRANSPORT_CoreHandle *h,
                const struct GNUNET_PeerIdentity *peer)
{
  return GNUNET_CONTAINER_multipeermap_get (h->neighbours, peer);
}
 
 
static int
neighbour_delete (void *cls, const struct GNUNET_PeerIdentity *key, void *value)
{
  struct GNUNET_TRANSPORT_CoreHandle *handle = cls;
  struct Neighbour *n = value;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Dropping entry for neighbour `%s'.\n",
       GNUNET_i2s (key));
  if (NULL != handle->nd_cb)
    handle->nd_cb (handle->cls, &n->id, n->handlers_cls);
  if (NULL != n->env)
  {
    GNUNET_MQ_send_cancel (n->env);
    n->env = NULL;
  }
  GNUNET_MQ_destroy (n->mq);
  GNUNET_assert (NULL == n->mq);
  GNUNET_assert (
    GNUNET_YES ==
    GNUNET_CONTAINER_multipeermap_remove (handle->neighbours, key, n));
  GNUNET_free (n);
  return GNUNET_YES;
}
 
 
static void
mq_error_handler (void *cls, enum GNUNET_MQ_Error error)
{
  struct GNUNET_TRANSPORT_CoreHandle *h = cls;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Error %u received from transport service, disconnecting temporarily.\n",
       error);
  disconnect_and_schedule_reconnect (h);
}
 
 
static void
notify_send_done (void *cls)
{
  struct Neighbour *n = cls;
 
  n->awaiting_done = GNUNET_NO;
  n->env = NULL;
  if (0 < n->ready_window)
    GNUNET_MQ_impl_send_continue (n->mq);
}
 
 
static void
do_send (struct Neighbour *n)
{
  GNUNET_assert (0 < n->ready_window);
  GNUNET_assert (NULL != n->env);
  n->ready_window--;
  n->awaiting_done = GNUNET_YES;
  GNUNET_MQ_notify_sent (n->env, &notify_send_done, n);
  GNUNET_MQ_send (n->h->mq, n->env);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Passed message of type %u for neighbour `%s' to TRANSPORT. ready_window %u\n",
       ntohs (GNUNET_MQ_env_get_msg (n->env)->type),
       GNUNET_i2s (&n->id),
       n->ready_window);
}
 
 
static void
mq_send_impl (struct GNUNET_MQ_Handle *mq,
              const struct GNUNET_MessageHeader *msg,
              void *impl_state)
{
  struct Neighbour *n = impl_state;
  struct OutboundMessage *obm;
  uint16_t msize;
 
  msize = ntohs (msg->size);
  if (msize >= GNUNET_MAX_MESSAGE_SIZE - sizeof(*obm))
  {
    GNUNET_break (0);
    GNUNET_MQ_impl_send_continue (mq);
    return;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "CORE requested transmission of message of type %u to neighbour `%s'.\n",
       ntohs (msg->type),
       GNUNET_i2s (&n->id));
 
  GNUNET_assert (NULL == n->env);
  n->env =
    GNUNET_MQ_msg_nested_mh (obm, GNUNET_MESSAGE_TYPE_TRANSPORT_SEND, msg);
  n->env_size = ntohs (msg->size);
  {
    struct GNUNET_MQ_Envelope *env;
    enum GNUNET_MQ_PriorityPreferences prio;
 
    env = GNUNET_MQ_get_current_envelope (mq);
    prio = GNUNET_MQ_env_get_options (env);
    obm->priority = htonl ((uint32_t) prio);
  }
  obm->peer = n->id;
  if (0 == n->ready_window)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Flow control delays transmission to CORE until we see SEND_OK.\n");
    return;   /* can't send yet, need to wait for SEND_OK */
  }
  do_send (n);
}
 
 
static void
mq_destroy_impl (struct GNUNET_MQ_Handle *mq, void *impl_state)
{
  struct Neighbour *n = impl_state;
 
  GNUNET_assert (mq == n->mq);
  n->mq = NULL;
}
 
 
static void
mq_cancel_impl (struct GNUNET_MQ_Handle *mq, void *impl_state)
{
  struct Neighbour *n = impl_state;
 
  n->ready_window++;
  if (GNUNET_YES == n->awaiting_done)
  {
    GNUNET_MQ_send_cancel (n->env);
    n->env = NULL;
    n->awaiting_done = GNUNET_NO;
  }
  else
  {
    GNUNET_assert (0 == n->ready_window);
    n->env = NULL;
  }
}
 
 
static void
peer_mq_error_handler (void *cls, enum GNUNET_MQ_Error error)
{
  struct Neighbour *n = cls;
 
  if (GNUNET_MQ_ERROR_MALFORMED == error)
    GNUNET_break_op (0);
  // TODO Look into bug #7887
 
  GNUNET_TRANSPORT_core_receive_continue (n->h, &n->id);
}
 
 
static void
handle_connect (void *cls, const struct ConnectInfoMessage *cim)
{
  struct GNUNET_TRANSPORT_CoreHandle *h = cls;
  struct Neighbour *n;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Receiving CONNECT message for `%s'\n",
       GNUNET_i2s (&cim->id));
  n = neighbour_find (h, &cim->id);
  if (NULL != n)
  {
    GNUNET_break (0);
    disconnect_and_schedule_reconnect (h);
    return;
  }
  n = GNUNET_new (struct Neighbour);
  n->id = cim->id;
  n->h = h;
  n->ready_window = SEND_WINDOW_SIZE;
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CONTAINER_multipeermap_put (
                   h->neighbours,
                   &n->id,
                   n,
                   GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
 
  n->mq = GNUNET_MQ_queue_for_callbacks (&mq_send_impl,
                                         &mq_destroy_impl,
                                         &mq_cancel_impl,
                                         n,
                                         h->handlers,
                                         &peer_mq_error_handler,
                                         n);
  if (NULL != h->nc_cb)
  {
    n->handlers_cls = h->nc_cb (h->cls, &n->id, n->mq);
    GNUNET_MQ_set_handlers_closure (n->mq, n->handlers_cls);
  }
}
 
 
static void
handle_disconnect (void *cls, const struct DisconnectInfoMessage *dim)
{
  struct GNUNET_TRANSPORT_CoreHandle *h = cls;
  struct Neighbour *n;
 
  GNUNET_break (ntohl (dim->reserved) == 0);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Receiving DISCONNECT message for `%s'.\n",
       GNUNET_i2s (&dim->peer));
  n = neighbour_find (h, &dim->peer);
  if (NULL == n)
  {
    GNUNET_break (0);
    disconnect_and_schedule_reconnect (h);
    return;
  }
  GNUNET_assert (GNUNET_YES == neighbour_delete (h, &dim->peer, n));
}
 
 
static void
handle_send_ok (void *cls, const struct SendOkMessage *okm)
{
  struct GNUNET_TRANSPORT_CoreHandle *h = cls;
  struct Neighbour *n;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Receiving SEND_OK message for transmission to %s\n",
       GNUNET_i2s (&okm->peer));
 
  n = neighbour_find (h, &okm->peer);
 
  if (NULL == n)
  {
    /* A SEND_OK returns one unit of *this peer's* send window, and that
       window lives in the `struct Neighbour' we just failed to find.  So a
       SEND_OK for a peer we already dropped has nothing left to credit and
       nothing left to break: it is a message that was in flight when the
       DISCONNECT overtook it, which is ordinary and not the service
       misbehaving.
       It used to reconnect here, which threw away every *other* neighbour
       too and forced a fresh key exchange with all of them -- turning one
       raced link teardown into a full-mesh outage.  Ignore it instead. */
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Discarding SEND_OK for `%s', not connected (anymore)\n",
         GNUNET_i2s (&okm->peer));
    return;
  }
 
  if ((GNUNET_NO == n->awaiting_done) &&
      (NULL != n->env) &&
      (0 == n->ready_window))
  {
    n->ready_window++;
    do_send (n);
    return;
  }
  else if ((GNUNET_NO == n->awaiting_done) &&
           (0 == n->ready_window))
  {
    n->ready_window++;
    GNUNET_MQ_impl_send_continue (n->mq);
    return;
  }
  n->ready_window++;
}
 
 
static int
check_recv (void *cls, const struct InboundMessage *im)
{
  const struct GNUNET_MessageHeader *imm;
  uint16_t size;
 
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "check_recv\n");
  size = ntohs (im->header.size) - sizeof(*im);
  if (size < sizeof(struct GNUNET_MessageHeader))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  imm = (const struct GNUNET_MessageHeader *) &im[1];
  if (ntohs (imm->size) != size)
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}
 
 
static void
handle_recv (void *cls, const struct InboundMessage *im)
{
  struct GNUNET_TRANSPORT_CoreHandle *h = cls;
  const struct GNUNET_MessageHeader *imm =
    (const struct GNUNET_MessageHeader *) &im[1];
  struct Neighbour *n;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Received message of type %u with %u bytes from `%s'.\n",
       (unsigned int) ntohs (imm->type),
       (unsigned int) ntohs (imm->size),
       GNUNET_i2s (&im->peer));
  n = neighbour_find (h, &im->peer);
  if (NULL == n)
  {
    GNUNET_break (0);
    disconnect_and_schedule_reconnect (h);
    return;
  }
  GNUNET_MQ_inject_message (n->mq, imm);
}
 
 
static void
reconnect (void *cls)
{
  struct GNUNET_TRANSPORT_CoreHandle *h = cls;
  struct GNUNET_MQ_MessageHandler handlers[] =
  { GNUNET_MQ_hd_fixed_size (connect,
                             GNUNET_MESSAGE_TYPE_TRANSPORT_CONNECT,
                             struct ConnectInfoMessage,
                             h),
    GNUNET_MQ_hd_fixed_size (disconnect,
                             GNUNET_MESSAGE_TYPE_TRANSPORT_DISCONNECT,
                             struct DisconnectInfoMessage,
                             h),
    GNUNET_MQ_hd_fixed_size (send_ok,
                             GNUNET_MESSAGE_TYPE_TRANSPORT_SEND_OK,
                             struct SendOkMessage,
                             h),
    GNUNET_MQ_hd_var_size (recv,
                           GNUNET_MESSAGE_TYPE_TRANSPORT_RECV,
                           struct InboundMessage,
                           h),
    GNUNET_MQ_handler_end () };
  struct GNUNET_MQ_Envelope *env;
  struct StartMessage *s;
  uint32_t options;
 
  h->reconnect_task = NULL;
  LOG (GNUNET_ERROR_TYPE_DEBUG, "Connecting to transport service.\n");
  GNUNET_assert (NULL == h->mq);
  h->mq =
    GNUNET_CLIENT_connect (h->cfg, "transport", handlers, &mq_error_handler, h);
  h->restarted_at = GNUNET_TIME_absolute_get ();
  if (NULL == h->mq)
    return;
  env = GNUNET_MQ_msg (s, GNUNET_MESSAGE_TYPE_TRANSPORT_START);
  options = 0;
  if (h->check_self)
    options |= 1;
  if (NULL != h->handlers)
    options |= 2;
  s->options = htonl (options);
  s->self = h->self;
  GNUNET_MQ_send (h->mq, env);
}
 
 
static void
disconnect (struct GNUNET_TRANSPORT_CoreHandle *h)
{
  GNUNET_CONTAINER_multipeermap_iterate (h->neighbours, &neighbour_delete, h);
  if (NULL != h->mq)
  {
    GNUNET_MQ_destroy (h->mq);
    h->mq = NULL;
  }
}
 
 
static void
disconnect_and_schedule_reconnect (struct GNUNET_TRANSPORT_CoreHandle *h)
{
  GNUNET_assert (NULL == h->reconnect_task);
  disconnect (h);
  {
    /* Reduce delay based on runtime of the connection,
       so that there is a cool-down if a connection is up
       for a while. */
    struct GNUNET_TIME_Relative runtime;
    unsigned int minutes;
 
    runtime = GNUNET_TIME_absolute_get_duration (h->restarted_at);
    minutes = runtime.rel_value_us / GNUNET_TIME_UNIT_MINUTES.rel_value_us;
    if (minutes > 31)
      h->reconnect_delay = GNUNET_TIME_UNIT_ZERO;
    else
      h->reconnect_delay.rel_value_us >>= minutes;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Scheduling task to reconnect to transport service in %s.\n",
       GNUNET_STRINGS_relative_time_to_string (h->reconnect_delay, GNUNET_YES));
  h->reconnect_task =
    GNUNET_SCHEDULER_add_delayed (h->reconnect_delay, &reconnect, h);
  h->reconnect_delay = GNUNET_TIME_STD_BACKOFF (h->reconnect_delay);
}
 
 
struct GNUNET_MQ_Handle *
GNUNET_TRANSPORT_core_get_mq (struct GNUNET_TRANSPORT_CoreHandle *handle,
                              const struct GNUNET_PeerIdentity *peer)
{
  struct Neighbour *n;
 
  n = neighbour_find (handle, peer);
  if (NULL == n)
    return NULL;
  return n->mq;
}
 
 
void
GNUNET_TRANSPORT_core_receive_continue (struct GNUNET_TRANSPORT_CoreHandle *ch,
                                        const struct GNUNET_PeerIdentity *pid)
{
  struct GNUNET_MQ_Envelope *env;
  struct RecvOkMessage *rok;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Message for %s finished CORE processing, sending RECV_OK.\n",
       GNUNET_i2s (pid));
  if (NULL == ch->mq)
    return;
  env = GNUNET_MQ_msg (rok, GNUNET_MESSAGE_TYPE_TRANSPORT_RECV_OK);
  rok->increase_window_delta = htonl (1);
  rok->peer = *pid;
  GNUNET_MQ_send (ch->mq, env);
}
 
 
struct GNUNET_TRANSPORT_CoreHandle *
GNUNET_TRANSPORT_core_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
                               const struct GNUNET_PeerIdentity *self, // XXX
                               const struct GNUNET_MQ_MessageHandler *handlers,
                               void *cls,
                               GNUNET_TRANSPORT_NotifyConnect nc,
                               GNUNET_TRANSPORT_NotifyDisconnect nd)
{
  struct GNUNET_TRANSPORT_CoreHandle *h;
  unsigned int i;
 
  h = GNUNET_new (struct GNUNET_TRANSPORT_CoreHandle);
  if (NULL != self)
  {
    h->self = *self;
    h->check_self = GNUNET_YES;
  }
  h->cfg = cfg;
  h->cls = cls;
  h->nc_cb = nc;
  h->nd_cb = nd;
  h->reconnect_delay = GNUNET_TIME_UNIT_ZERO;
  if (NULL != handlers)
  {
    for (i = 0; NULL != handlers[i].cb; i++)
      ;
    h->handlers = GNUNET_new_array (i + 1, struct GNUNET_MQ_MessageHandler);
    GNUNET_memcpy (h->handlers,
                   handlers,
                   i * sizeof(struct GNUNET_MQ_MessageHandler));
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG, "Connecting to transport service\n");
  reconnect (h);
  if (NULL == h->mq)
  {
    GNUNET_free (h->handlers);
    GNUNET_free (h);
    return NULL;
  }
  h->neighbours =
    GNUNET_CONTAINER_multipeermap_create (STARTING_NEIGHBOURS_SIZE, GNUNET_YES);
  return h;
}
 
 
void
GNUNET_TRANSPORT_core_disconnect (struct GNUNET_TRANSPORT_CoreHandle *handle)
{
  LOG (GNUNET_ERROR_TYPE_DEBUG, "Transport disconnect called!\n");
  /* this disconnects all neighbours... */
  disconnect (handle);
  /* and now we stop trying to connect again... */
  if (NULL != handle->reconnect_task)
  {
    GNUNET_SCHEDULER_cancel (handle->reconnect_task);
    handle->reconnect_task = NULL;
  }
  GNUNET_CONTAINER_multipeermap_destroy (handle->neighbours);
  handle->neighbours = NULL;
  GNUNET_free (handle->handlers);
  handle->handlers = NULL;
  GNUNET_free (handle);
}
 
 
/* end of transport_api_core.c */