namecache_api.c

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/*
     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
 */

#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_crypto_lib.h"
#include "gnunet_constants.h"
#include "gnunet_dnsparser_lib.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__)


struct GNUNET_NAMECACHE_QueueEntry {
  struct GNUNET_NAMECACHE_QueueEntry *next;

  struct GNUNET_NAMECACHE_QueueEntry *prev;

  struct GNUNET_NAMECACHE_Handle *nsh;

  GNUNET_NAMECACHE_ContinuationWithStatus cont;

  void *cont_cls;

  GNUNET_NAMECACHE_BlockProcessor block_proc;

  void *block_proc_cls;

  uint32_t op_id;
};


struct GNUNET_NAMECACHE_Handle {
  const struct GNUNET_CONFIGURATION_Handle *cfg;

  struct GNUNET_MQ_Handle *mq;

  struct GNUNET_CLIENT_TransmitHandle *th;

  struct GNUNET_NAMECACHE_QueueEntry *op_head;

  struct GNUNET_NAMECACHE_QueueEntry *op_tail;

  struct GNUNET_SCHEDULER_Task *reconnect_task;

  struct GNUNET_TIME_Relative reconnect_delay;

  int reconnect;

  uint32_t last_op_id_used;
};


static void
force_reconnect(struct GNUNET_NAMECACHE_Handle *h);


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;
}


static int
check_lookup_block_response(void *cls,
                            const struct LookupBlockResponseMessage *msg)
{
  /* any length will do, format validation is in handler */
  return GNUNET_OK;
}


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 + sizeof(struct GNUNET_GNSRECORD_Block)] GNUNET_ALIGN;
    struct GNUNET_GNSRECORD_Block *block;

    block = (struct GNUNET_GNSRECORD_Block *)buf;
    block->signature = msg->signature;
    block->derived_key = msg->derived_key;
    block->purpose.purpose = htonl(GNUNET_SIGNATURE_PURPOSE_GNS_RECORD_SIGN);
    block->purpose.size = htonl(size +
                                sizeof(struct GNUNET_TIME_AbsoluteNBO) +
                                sizeof(struct GNUNET_CRYPTO_EccSignaturePurpose));
    block->expiration_time = msg->expire;
    GNUNET_memcpy(&block[1],
                  &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);
}


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);
}


static void
mq_error_handler(void *cls,
                 enum GNUNET_MQ_Error error)
{
  struct GNUNET_NAMECACHE_Handle *h = cls;

  force_reconnect(h);
}


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);
}


static void
reconnect_task(void *cls)
{
  struct GNUNET_NAMECACHE_Handle *h = cls;

  h->reconnect_task = NULL;
  reconnect(h);
}


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);
}


static uint32_t
get_op_id(struct GNUNET_NAMECACHE_Handle *h)
{
  return h->last_op_id_used++;
}


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;
}


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);
}


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 = ntohl(block->purpose.size);
  GNUNET_assert(blen > (sizeof(struct GNUNET_TIME_AbsoluteNBO) +
                        sizeof(struct GNUNET_CRYPTO_EccSignaturePurpose)));
  blen -= (sizeof(struct GNUNET_TIME_AbsoluteNBO) +
           sizeof(struct GNUNET_CRYPTO_EccSignaturePurpose));
  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);
  msg->expire = block->expiration_time;
  msg->signature = block->signature;
  msg->derived_key = block->derived_key;
  GNUNET_memcpy(&msg[1],
                &block[1],
                blen);
  GNUNET_MQ_send(h->mq,
                 env);
  return qe;
}


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;
}


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 */