/*
      This file is part of GNUnet
      Copyright (C) 2008--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 testbed/gnunet-daemon-testbed-blacklist.c
 * @brief daemon to restrict incoming connections from other peers at the
 *          transport layer of a peer
 * @author Sree Harsha Totakura <sreeharsha@totakura.in>
 */

#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_transport_service.h"
#include "gnunet_transport_manipulation_service.h"
#include "gnunet_ats_service.h"
#include "gnunet_testing_lib.h"
#include <sqlite3.h>

/**
 * Logging shorthand
 */
#define LOG(type, ...)                           \
  GNUNET_log(type, __VA_ARGS__)

/**
 * Debug logging shorthand
 */
#define DEBUG(...)                              \
  LOG(GNUNET_ERROR_TYPE_DEBUG, __VA_ARGS__)

/**
 * Log an error message at log-level 'level' that indicates
 * a failure of the command 'cmd' on file 'filename'
 * with the message given by strerror(errno).
 */
#define LOG_SQLITE(db, msg, level, cmd)                                 \
  do {                                                                  \
      GNUNET_log_from(level, "sqlite", _("`%s' failed at %s:%d with error: %s\n"), \
                      cmd, __FILE__, __LINE__, sqlite3_errmsg(db));  \
      if (msg != NULL)                                                    \
      GNUNET_asprintf (msg, _("`%s' failed at %s:%u with error: %s"), cmd, \
                       __FILE__, __LINE__, sqlite3_errmsg(db));     \
    } while (0)


/**
 * The map to store the peer identities to allow/deny
 */
static struct GNUNET_CONTAINER_MultiPeerMap *map;

/**
 * The database connection
 */
static struct sqlite3 *db;

/**
 * The blacklist handle we obtain from transport when we register ourselves for
 * access control
 */
static struct GNUNET_TRANSPORT_Blacklist *bh;

/**
 * The hostkeys file
 */
struct GNUNET_DISK_FileHandle *hostkeys_fd;

/**
 * The hostkeys map
 */
static struct GNUNET_DISK_MapHandle *hostkeys_map;

/**
 * The hostkeys data
 */
static void *hostkeys_data;

/**
 * Handle to the transport service.  This is used for setting link metrics
 */
static struct GNUNET_TRANSPORT_ManipulationHandle *transport;

/**
 * The number of hostkeys in the hostkeys array
 */
static unsigned int num_hostkeys;


/**
 * @ingroup hashmap
 * Iterator over hash map entries.
 *
 * @param cls closure
 * @param key current key code
 * @param value value in the hash map
 * @return #GNUNET_YES if we should continue to
 *         iterate,
 *         #GNUNET_NO if not.
 */
static int
iterator(void *cls, const struct GNUNET_PeerIdentity *key, void *value)
{
  GNUNET_assert(GNUNET_YES == GNUNET_CONTAINER_multipeermap_remove(map, key,
                                                                   value));
  return GNUNET_YES;
}


/**
 * Cleaup and destroy the map
 */
static void
cleanup_map()
{
  if (NULL != map)
    {
      GNUNET_assert(GNUNET_SYSERR != GNUNET_CONTAINER_multipeermap_iterate(map,
                                                                           &iterator,
                                                                           NULL));
      GNUNET_CONTAINER_multipeermap_destroy(map);
      map = NULL;
    }
}


/**
 * Function that decides if a connection is acceptable or not.
 *
 * @param cls closure
 * @param pid peer to approve or disapproave
 * @return GNUNET_OK if the connection is allowed, GNUNET_SYSERR if not
 */
static int
check_access(void *cls, const struct GNUNET_PeerIdentity * pid)
{
  int contains;

  GNUNET_assert(NULL != map);
  contains = GNUNET_CONTAINER_multipeermap_contains(map, pid);
  if (GNUNET_YES == contains)
    {
      DEBUG("Permitting `%s'\n", GNUNET_i2s(pid));
      return GNUNET_OK;
    }
  DEBUG("Not permitting `%s'\n", GNUNET_i2s(pid));
  return GNUNET_SYSERR;
}


static int
get_identity(unsigned int offset,
             struct GNUNET_PeerIdentity *id)
{
  struct GNUNET_CRYPTO_EddsaPrivateKey private_key;

  if (offset >= num_hostkeys)
    return GNUNET_SYSERR;
  GNUNET_memcpy(&private_key,
                hostkeys_data + (offset * GNUNET_TESTING_HOSTKEYFILESIZE),
                GNUNET_TESTING_HOSTKEYFILESIZE);
  GNUNET_CRYPTO_eddsa_key_get_public(&private_key,
                                     &id->public_key);
  return GNUNET_OK;
}


/**
 * Whilelist entry
 */
struct WhiteListRow {
  /**
   * Next ptr
   */
  struct WhiteListRow *next;

  /**
   * The offset where to find the hostkey for the peer
   */
  unsigned int id;

  /**
   * Latency to be assigned to the link
   */
  int latency;
};


/**
 * Function to load keys
 */
static int
load_keys(const struct GNUNET_CONFIGURATION_Handle *c)
{
  char *data_dir;
  char *idfile;
  uint64_t fsize;

  data_dir = NULL;
  idfile = NULL;
  fsize = 0;
  data_dir = GNUNET_OS_installation_get_path(GNUNET_OS_IPK_DATADIR);
  GNUNET_asprintf(&idfile, "%s/testing_hostkeys.ecc", data_dir);
  GNUNET_free(data_dir);
  data_dir = NULL;
  if (GNUNET_OK !=
      GNUNET_DISK_file_size(idfile, &fsize, GNUNET_YES, GNUNET_YES))
    {
      GNUNET_free(idfile);
      return GNUNET_SYSERR;
    }
  if (0 != (fsize % GNUNET_TESTING_HOSTKEYFILESIZE))
    {
      LOG(GNUNET_ERROR_TYPE_ERROR,
          _("Incorrect hostkey file format: %s\n"), idfile);
      GNUNET_free(idfile);
      return GNUNET_SYSERR;
    }
  hostkeys_fd = GNUNET_DISK_file_open(idfile, GNUNET_DISK_OPEN_READ,
                                      GNUNET_DISK_PERM_NONE);
  if (NULL == hostkeys_fd)
    {
      GNUNET_log_strerror_file(GNUNET_ERROR_TYPE_ERROR, "open", idfile);
      GNUNET_free(idfile);
      return GNUNET_SYSERR;
    }
  GNUNET_free(idfile);
  idfile = NULL;
  hostkeys_data = GNUNET_DISK_file_map(hostkeys_fd,
                                       &hostkeys_map,
                                       GNUNET_DISK_MAP_TYPE_READ,
                                       fsize);
  if (NULL == hostkeys_data)
    {
      GNUNET_log_strerror(GNUNET_ERROR_TYPE_ERROR, "mmap");
      return GNUNET_SYSERR;
    }
  num_hostkeys = fsize / GNUNET_TESTING_HOSTKEYFILESIZE;
  return GNUNET_OK;
}


/**
 * Function to unload keys
 */
static void
unload_keys()
{
  if (NULL != hostkeys_map)
    {
      GNUNET_assert(NULL != hostkeys_data);
      GNUNET_DISK_file_unmap(hostkeys_map);
      hostkeys_map = NULL;
      hostkeys_data = NULL;
    }
  if (NULL != hostkeys_fd)
    {
      GNUNET_DISK_file_close(hostkeys_fd);
      hostkeys_fd = NULL;
    }
}


/**
 * Shutdown task to cleanup our resources and exit.
 *
 * @param cls NULL
 */
static void
do_shutdown(void *cls)
{
  if (NULL != transport)
    {
      GNUNET_TRANSPORT_manipulation_disconnect(transport);
      transport = NULL;
    }
  cleanup_map();
  unload_keys();
  if (NULL != bh)
    GNUNET_TRANSPORT_blacklist_cancel(bh);
}


/**
 * Function to read whitelist rows from the database
 *
 * @param db the database connection
 * @param pid the identity of this peer
 * @param wl_rows where to store the retrieved whitelist rows
 * @return GNUNET_SYSERR upon error OR the number of rows retrieved
 */
static int
db_read_whitelist(struct sqlite3 *db, int pid, struct WhiteListRow **wl_rows)
{
  static const char *query_wl = "SELECT oid, latency FROM whitelist WHERE (id == ?);";
  struct sqlite3_stmt *stmt_wl;
  struct WhiteListRow *lr;
  int nrows;
  int ret;

  if (SQLITE_OK != (ret = sqlite3_prepare_v2(db, query_wl, -1, &stmt_wl, NULL)))
    {
      LOG_SQLITE(db, NULL, GNUNET_ERROR_TYPE_ERROR, "sqlite3_prepare_v2");
      return GNUNET_SYSERR;
    }
  if (SQLITE_OK != (ret = sqlite3_bind_int(stmt_wl, 1, pid)))
    {
      LOG_SQLITE(db, NULL, GNUNET_ERROR_TYPE_ERROR, "sqlite3_bind_int");
      sqlite3_finalize(stmt_wl);
      return GNUNET_SYSERR;
    }
  nrows = 0;
  do
    {
      ret = sqlite3_step(stmt_wl);
      if (SQLITE_ROW != ret)
        break;
      nrows++;
      lr = GNUNET_new(struct WhiteListRow);
      lr->id = sqlite3_column_int(stmt_wl, 0);
      lr->latency = sqlite3_column_int(stmt_wl, 1);
      lr->next = *wl_rows;
      *wl_rows = lr;
    }
  while (1);
  sqlite3_finalize(stmt_wl);
  return nrows;
}


/**
 * Main function that will be run.
 *
 * @param cls closure
 * @param args remaining command-line arguments
 * @param cfgfile name of the configuration file used (for saving, can be NULL!)
 * @param c configuration
 */
static void
run(void *cls, char *const *args, const char *cfgfile,
    const struct GNUNET_CONFIGURATION_Handle *c)
{
  char *dbfile;
  struct WhiteListRow *wl_head;
  struct WhiteListRow *wl_entry;
  struct GNUNET_PeerIdentity identity;
  struct GNUNET_ATS_Properties prop;
  struct GNUNET_TIME_Relative delay;
  unsigned long long pid;
  unsigned int nrows;
  int ret;

  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_number(c, "TESTBED",
                                            "PEERID", &pid))
    {
      GNUNET_break(0);
      return;
    }
  if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_filename(c, "TESTBED-UNDERLAY",
                                                           "DBFILE",
                                                           &dbfile))
    {
      GNUNET_break(0);
      return;
    }
  if (SQLITE_OK != (ret = sqlite3_open_v2(dbfile, &db, SQLITE_OPEN_READONLY, NULL)))
    {
      if (NULL != db)
        {
          LOG_SQLITE(db, NULL, GNUNET_ERROR_TYPE_ERROR, "sqlite_open_v2");
          GNUNET_break(SQLITE_OK == sqlite3_close(db));
        }
      else
        LOG(GNUNET_ERROR_TYPE_ERROR, "Cannot open sqlite file %s\n", dbfile);
      GNUNET_free(dbfile);
      return;
    }
  DEBUG("Opened database %s\n", dbfile);
  GNUNET_free(dbfile);
  dbfile = NULL;
  wl_head = NULL;
  if (GNUNET_OK != load_keys(c))
    goto close_db;

  transport = GNUNET_TRANSPORT_manipulation_connect(c);
  if (NULL == transport)
    {
      GNUNET_break(0);
      return;
    }
  /* read and process whitelist */
  nrows = 0;
  wl_head = NULL;
  nrows = db_read_whitelist(db, pid, &wl_head);
  if ((GNUNET_SYSERR == nrows) || (0 == nrows))
    {
      GNUNET_TRANSPORT_manipulation_disconnect(transport);
      goto close_db;
    }
  map = GNUNET_CONTAINER_multipeermap_create(nrows, GNUNET_NO);
  while (NULL != (wl_entry = wl_head))
    {
      wl_head = wl_entry->next;
      delay.rel_value_us = wl_entry->latency;
      memset(&prop, 0, sizeof(prop));
      GNUNET_assert(GNUNET_OK == get_identity(wl_entry->id, &identity));
      GNUNET_break(GNUNET_OK ==
                   GNUNET_CONTAINER_multipeermap_put(map, &identity, &identity,
                                                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST));
      DEBUG("Setting %u ms latency to peer `%s'\n",
            wl_entry->latency,
            GNUNET_i2s(&identity));
      GNUNET_TRANSPORT_manipulation_set(transport,
                                        &identity,
                                        &prop,
                                        delay,
                                        delay);
      GNUNET_free(wl_entry);
    }
  bh = GNUNET_TRANSPORT_blacklist(c, &check_access, NULL);
  GNUNET_SCHEDULER_add_shutdown(&do_shutdown, NULL);

close_db:
  GNUNET_break(SQLITE_OK == sqlite3_close(db));
}


/**
 * The main function.
 *
 * @param argc number of arguments from the command line
 * @param argv command line arguments
 * @return 0 ok, 1 on error
 */
int
main(int argc, char *const *argv)
{
  static const struct GNUNET_GETOPT_CommandLineOption options[] = {
    GNUNET_GETOPT_OPTION_END
  };
  int ret;

  if (GNUNET_OK != GNUNET_STRINGS_get_utf8_args(argc, argv, &argc, &argv))
    return 2;
#ifdef SQLITE_CONFIG_MMAP_SIZE
  (void)sqlite3_config(SQLITE_CONFIG_MMAP_SIZE, 512000, 256000000);
#endif
  ret =
    (GNUNET_OK ==
     GNUNET_PROGRAM_run(argc, argv, "testbed-underlay",
                        _
                          ("Daemon to restrict underlay network in testbed deployments"),
                        options, &run, NULL)) ? 0 : 1;
  GNUNET_free((void*)argv);
  return ret;
}