exchange/src/auditor/taler-auditor.c

/*
  This file is part of TALER
  Copyright (C) 2016, 2017 Inria

  TALER is free software; you can redistribute it and/or modify it under the
  terms of the GNU General Public License as published by the Free Software
  Foundation; either version 3, or (at your option) any later version.

  TALER 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 General Public License for more details.

  You should have received a copy of the GNU General Public License along with
  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
*/
/**
 * @file auditor/taler-auditor.c
 * @brief audits an exchange database.
 * @author Christian Grothoff
 *
 * NOTE:
 * - This auditor does not verify that 'reserves_in' actually matches
 *   the wire transfers from the bank. This needs to be checked separately!
 * - Similarly, we do not check that the outgoing wire transfers match those
 *   given in the aggregation_tracking table. This needs to be checked separately!
 *
 * TODO:
 * - modify auditordb to allow multiple last serial IDs per table in progress tracking
 * - implement coin/denomination audit
 * - implement merchant deposit audit
 *   - see if we need more tables there
 * - write reporting logic to output nice report beyond GNUNET_log()
 *
 * EXTERNAL:
 * - add tool to pay-back expired reserves (#4956), and support here
 * - add tool to verify 'reserves_in' from wire transfer inspection
 * - add tool to trigger computation of historic revenues
 *   (move balances from 'current' revenue/profits to 'historic' tables)
 */
#include "platform.h"
#include <gnunet/gnunet_util_lib.h>
#include "taler_auditordb_plugin.h"
#include "taler_exchangedb_plugin.h"
#include "taler_signatures.h"


/**
 * Return value from main().
 */
static int global_ret;

/**
 * Handle to access the exchange's database.
 */
static struct TALER_EXCHANGEDB_Plugin *edb;

/**
 * Our session with the #edb.
 */
static struct TALER_EXCHANGEDB_Session *esession;

/**
 * Handle to access the auditor's database.
 */
static struct TALER_AUDITORDB_Plugin *adb;

/**
 * Our session with the #adb.
 */
static struct TALER_AUDITORDB_Session *asession;

/**
 * Master public key of the exchange to audit.
 */
static struct TALER_MasterPublicKeyP master_pub;

/**
 * Last reserve_in serial ID seen.
 */
static struct TALER_AUDITORDB_ProgressPoint pp;


/* ***************************** Report logic **************************** */

/**
 * Report a (serious) inconsistency in the exchange's database.
 *
 * @param table affected table
 * @param rowid affected row, UINT64_MAX if row is missing
 * @param diagnostic message explaining the problem
 */
static void
report_row_inconsistency (const char *table,
                          uint64_t rowid,
                          const char *diagnostic)
{
  // TODO: implement proper reporting logic writing to file.
  GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
              "Database inconsistency detected in table %s at row %llu: %s\n",
              table,
              (unsigned long long) rowid,
              diagnostic);
}


/**
 * Report a minor inconsistency in the exchange's database (i.e. something
 * relating to timestamps that should have no financial implications).
 *
 * @param table affected table
 * @param rowid affected row, UINT64_MAX if row is missing
 * @param diagnostic message explaining the problem
 */
static void
report_row_minor_inconsistency (const char *table,
                                uint64_t rowid,
                                const char *diagnostic)
{
  // TODO: implement proper reporting logic writing to file.
  GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
              "Minor inconsistency detected in table %s at row %llu: %s\n",
              table,
              (unsigned long long) rowid,
              diagnostic);
}


/**
 * Report a global inconsistency with respect to a reserve.
 *
 * @param reserve_pub the affected reserve
 * @param expected expected amount
 * @param observed observed amount
 * @param diagnostic message explaining what @a expected and @a observed refer to
 */
static void
report_reserve_inconsistency (const struct TALER_ReservePublicKeyP *reserve_pub,
                              const struct TALER_Amount *expected,
                              const struct TALER_Amount *observed,
                              const char *diagnostic)
{
  // TODO: implement proper reporting logic writing to file, include amounts.
  GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
              "Reserve inconsistency detected affecting reserve %s: %s\n",
              TALER_B2S (reserve_pub),
              diagnostic);
}


/**
 * Report the final result on the reserve balances of the exchange.
 * The reserve must have @a total_balance in its escrow account just
 * to cover outstanding reserve funds (outstanding coins are on top).
 * The reserve has made @a total_fee_balance in profit from withdrawal
 * operations alone.
 *
 * Note that this is for the "ongoing" reporting period.  Historic
 * revenue (as stored via the "insert_historic_reserve_revenue")
 * is not included in the @a total_fee_balance.
 *
 * @param total_balance how much money (in total) is left in all of the
 *        reserves (that has not been withdrawn)
 * @param total_fee_balance how much money (in total) did the reserve
 *        make from withdrawal fees
 */
static void
report_reserve_balance (const struct TALER_Amount *total_balance,
                        const struct TALER_Amount *total_fee_balance)
{
  char *balance;
  char *fees;

  balance = TALER_amount_to_string (total_balance);
  fees = TALER_amount_to_string (total_fee_balance);
  // TODO: implement proper reporting logic writing to file.
  GNUNET_log (GNUNET_ERROR_TYPE_MESSAGE,
              "Total escrow balance to be held for reserves: %s\n",
              balance);
  GNUNET_log (GNUNET_ERROR_TYPE_MESSAGE,
              "Total profits made from reserves: %s\n",
              fees);
  GNUNET_free (fees);
  GNUNET_free (balance);
}


/* ************************* Transaction-global state ************************ */

/**
 * Results about denominations, cached per-transaction.
 */
static struct GNUNET_CONTAINER_MultiHashMap *denominations;


/**
 * Obtain information about a @a denom_pub.
 *
 * @param denom_pub key to look up
 * @param[out] set to the hash of @a denom_pub, may be NULL
 * @param[out] dki set to detailed information about @a denom_pub, NULL if not found, must
 *                 NOT be freed by caller
 * @return #GNUNET_OK on success, #GNUNET_NO for not found, #GNUNET_SYSERR for DB error
 */
static int
get_denomination_info (const struct TALER_DenominationPublicKey *denom_pub,
                       const struct TALER_EXCHANGEDB_DenominationKeyInformationP **dki,
                       struct GNUNET_HashCode *dh)
{
  struct GNUNET_HashCode hc;
  struct TALER_EXCHANGEDB_DenominationKeyInformationP *dkip;
  int ret;

  if (NULL == dh)
    dh = &hc;
  GNUNET_CRYPTO_rsa_public_key_hash (denom_pub->rsa_public_key,
                                     dh);
  dkip = GNUNET_CONTAINER_multihashmap_get (denominations,
                                            dh);
  if (NULL != dkip)
    {
      /* cache hit */
      *dki = dkip;
      return GNUNET_OK;
    }
  dkip = GNUNET_new (struct TALER_EXCHANGEDB_DenominationKeyInformationP);
  ret = edb->get_denomination_info (edb->cls,
                                    esession,
                                    denom_pub,
                                    dkip);
  if (GNUNET_OK != ret)
  {
    GNUNET_free (dkip);
    GNUNET_break (GNUNET_NO == ret);
    *dki = NULL;
    return ret;
  }
  *dki = dkip;
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CONTAINER_multihashmap_put (denominations,
                                                    dh,
                                                    dkip,
                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  return GNUNET_OK;
}


/**
 * Free denomination key information.
 *
 * @param cls NULL
 * @param key unused
 * @param value the `struct TALER_EXCHANGEDB_DenominationKeyInformationP *` to free
 * @return #GNUNET_OK (continue to iterate)
 */
static int
free_dk_info (void *cls,
              const struct GNUNET_HashCode *key,
              void *value)
{
  struct TALER_EXCHANGEDB_DenominationKeyInformationP *dki = value;

  GNUNET_free (dki);
  return GNUNET_OK;
}


/**
 * Purge transaction global state cache, the transaction is
 * done and we do not want to have the state cross over to
 * the next transaction.
 */
static void
clear_transaction_state_cache ()
{
  if (NULL == denominations)
    return;
  GNUNET_CONTAINER_multihashmap_iterate (denominations,
                                         &free_dk_info,
                                         NULL);
  GNUNET_CONTAINER_multihashmap_destroy (denominations);
  denominations = NULL;
}


/* ***************************** Analyze reserves ************************ */
/* This logic checks the reserves_in, reserves_out and reserves-tables */

/**
 * Summary data we keep per reserve.
 */
struct ReserveSummary
{
  /**
   * Public key of the reserve.
   * Always set when the struct is first initialized.
   */
  struct TALER_ReservePublicKeyP reserve_pub;

  /**
   * Sum of all incoming transfers during this transaction.
   * Updated only in #handle_reserve_in().
   */
  struct TALER_Amount total_in;

  /**
   * Sum of all outgoing transfers during this transaction (includes fees).
   * Updated only in #handle_reserve_out().
   */
  struct TALER_Amount total_out;

  /**
   * Sum of withdraw fees encountered during this transaction.
   */
  struct TALER_Amount total_fee;

  /**
   * Previous balance of the reserve as remembered by the auditor.
   * (updated based on @e total_in and @e total_out at the end).
   */
  struct TALER_Amount a_balance;

  /**
   * Previous withdraw fee balance of the reserve, as remembered by the auditor.
   * (updated based on @e total_fee at the end).
   */
  struct TALER_Amount a_withdraw_fee_balance;

  /**
   * Previous reserve expiration data, as remembered by the auditor.
   * (updated on-the-fly in #handle_reserve_in()).
   */
  struct GNUNET_TIME_Absolute a_expiration_date;

  /**
   * Previous last processed reserve_in serial ID, as remembered by the auditor.
   * (updated on-the-fly in #handle_reserve_in()).
   */
  uint64_t a_last_reserve_in_serial_id;

  /**
   * Previous last processed reserve_out serial ID, as remembered by the auditor.
   * (updated on-the-fly in #handle_reserve_out()).
   */
  uint64_t a_last_reserve_out_serial_id;

  /**
   * Did we have a previous reserve info?  Used to decide between
   * UPDATE and INSERT later.  Initialized in
   * #load_auditor_reserve_summary() together with the a-* values
   * (if available).
   */
  int had_ri;

};


/**
 * Load the auditor's remembered state about the reserve into @a rs.
 * The "total_in" and "total_out" amounts of @a rs must already be
 * initialized (so we can determine the currency).
 *
 * @param[in|out] rs reserve summary to (fully) initialize
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on DB errors
 */
static int
load_auditor_reserve_summary (struct ReserveSummary *rs)
{
  int ret;
  uint64_t rowid;

  ret = adb->get_reserve_info (adb->cls,
                               asession,
                               &rs->reserve_pub,
                               &master_pub,
                               &rowid,
                               &rs->a_balance,
                               &rs->a_withdraw_fee_balance,
                               &rs->a_expiration_date,
                               &rs->a_last_reserve_in_serial_id,
                               &rs->a_last_reserve_out_serial_id);
  if (GNUNET_SYSERR == ret)
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  if (GNUNET_NO == ret)
  {
    rs->had_ri = GNUNET_NO;
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_get_zero (rs->total_in.currency,
                                          &rs->a_balance));
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_get_zero (rs->total_in.currency,
                                          &rs->a_withdraw_fee_balance));
    return GNUNET_OK;
  }
  rs->had_ri = GNUNET_YES;
  if ( (GNUNET_YES !=
        TALER_amount_cmp_currency (&rs->a_balance,
                                   &rs->a_withdraw_fee_balance)) ||
       (GNUNET_YES !=
        TALER_amount_cmp_currency (&rs->total_in,
                                   &rs->a_balance)) )
  {
    report_row_inconsistency ("auditor-reserve-info",
                              rowid,
                              "currencies for reserve differ");
    /* TODO: find a sane way to continue... */
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Closure to the various callbacks we make while checking a reserve.
 */
struct ReserveContext
{
  /**
   * Map from hash of reserve's public key to a `struct ReserveSummary`.
   */
  struct GNUNET_CONTAINER_MultiHashMap *reserves;

  /**
   * Total balance in all reserves (updated).
   */
  struct TALER_Amount total_balance;

  /**
   * Total withdraw fees gotten in all reserves (updated).
   */
  struct TALER_Amount total_fee_balance;

};


/**
 * Function called with details about incoming wire transfers.
 *
 * @param cls our `struct ReserveContext`
 * @param rowid unique serial ID for the refresh session in our DB
 * @param reserve_pub public key of the reserve (also the WTID)
 * @param credit amount that was received
 * @param sender_account_details information about the sender's bank account
 * @param transfer_details information that uniquely identifies the wire transfer
 * @param execution_date when did we receive the funds
 * @return #GNUNET_OK to continue to iterate, #GNUNET_SYSERR to stop
 */
static int
handle_reserve_in (void *cls,
                   uint64_t rowid,
                   const struct TALER_ReservePublicKeyP *reserve_pub,
                   const struct TALER_Amount *credit,
                   const json_t *sender_account_details,
                   const json_t *transfer_details,
                   struct GNUNET_TIME_Absolute execution_date)
{
  struct ReserveContext *rc = cls;
  struct GNUNET_HashCode key;
  struct ReserveSummary *rs;
  struct GNUNET_TIME_Absolute expiry;

  GNUNET_assert (rowid >= pp.last_reserve_in_serial_id); /* should be monotonically increasing */
  pp.last_reserve_in_serial_id = rowid + 1;
  GNUNET_CRYPTO_hash (reserve_pub,
                      sizeof (*reserve_pub),
                      &key);
  rs = GNUNET_CONTAINER_multihashmap_get (rc->reserves,
                                          &key);
  if (NULL == rs)
  {
    rs = GNUNET_new (struct ReserveSummary);
    rs->reserve_pub = *reserve_pub;
    rs->total_in = *credit;
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_get_zero (credit->currency,
                                          &rs->total_out));
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_get_zero (credit->currency,
                                          &rs->total_fee));
    if (GNUNET_OK !=
        load_auditor_reserve_summary (rs))
    {
      GNUNET_break (0);
      GNUNET_free (rs);
      return GNUNET_SYSERR;
    }
    GNUNET_assert (GNUNET_OK ==
                   GNUNET_CONTAINER_multihashmap_put (rc->reserves,
                                                      &key,
                                                      rs,
                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  }
  else
  {
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_add (&rs->total_in,
                                     &rs->total_in,
                                     credit));
  }
  GNUNET_assert (rowid >= rs->a_last_reserve_in_serial_id);
  rs->a_last_reserve_in_serial_id = rowid + 1;
  expiry = GNUNET_TIME_absolute_add (execution_date,
                                     TALER_IDLE_RESERVE_EXPIRATION_TIME);
  rs->a_expiration_date = GNUNET_TIME_absolute_max (rs->a_expiration_date,
                                                    expiry);
  return GNUNET_OK;
}


/**
 * Function called with details about withdraw operations.
 *
 * @param cls our `struct ReserveContext`
 * @param rowid unique serial ID for the refresh session in our DB
 * @param h_blind_ev blinded hash of the coin's public key
 * @param denom_pub public denomination key of the deposited coin
 * @param denom_sig signature over the deposited coin
 * @param reserve_pub public key of the reserve
 * @param reserve_sig signature over the withdraw operation
 * @param execution_date when did the wallet withdraw the coin
 * @param amount_with_fee amount that was withdrawn
 * @return #GNUNET_OK to continue to iterate, #GNUNET_SYSERR to stop
 */
static int
handle_reserve_out (void *cls,
                    uint64_t rowid,
                    const struct GNUNET_HashCode *h_blind_ev,
                    const struct TALER_DenominationPublicKey *denom_pub,
                    const struct TALER_DenominationSignature *denom_sig,
                    const struct TALER_ReservePublicKeyP *reserve_pub,
                    const struct TALER_ReserveSignatureP *reserve_sig,
                    struct GNUNET_TIME_Absolute execution_date,
                    const struct TALER_Amount *amount_with_fee)
{
  struct ReserveContext *rc = cls;
  struct TALER_WithdrawRequestPS wsrd;
  struct GNUNET_HashCode key;
  struct ReserveSummary *rs;
  const struct TALER_EXCHANGEDB_DenominationKeyInformationP *dki;
  struct TALER_Amount withdraw_fee;
  struct GNUNET_TIME_Absolute valid_start;
  struct GNUNET_TIME_Absolute expire_withdraw;
  int ret;

  /* should be monotonically increasing */
  GNUNET_assert (rowid >= pp.last_reserve_out_serial_id);
  pp.last_reserve_out_serial_id = rowid + 1;

  /* lookup denomination pub data (make sure denom_pub is valid, establish fees) */
  ret = get_denomination_info (denom_pub,
                               &dki,
                               &wsrd.h_denomination_pub);
  if (GNUNET_SYSERR == ret)
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  if (GNUNET_NO == ret)
  {
    report_row_inconsistency ("reserve_out",
                              rowid,
                              "denomination key not found (foreign key constraint violated)");
    return GNUNET_OK;
  }

  /* check that execution date is within withdraw range for denom_pub  */
  valid_start = GNUNET_TIME_absolute_ntoh (dki->properties.start);
  expire_withdraw = GNUNET_TIME_absolute_ntoh (dki->properties.expire_withdraw);
  if ( (valid_start.abs_value_us > execution_date.abs_value_us) ||
       (expire_withdraw.abs_value_us < execution_date.abs_value_us) )
  {
    report_row_minor_inconsistency ("reserve_out",
                                    rowid,
                                    "denomination key not valid at time of withdrawal");
  }

  /* check reserve_sig */
  wsrd.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_RESERVE_WITHDRAW);
  wsrd.purpose.size = htonl (sizeof (wsrd));
  TALER_amount_hton (&wsrd.amount_with_fee,
                     amount_with_fee);
  wsrd.withdraw_fee = dki->properties.fee_withdraw;
  wsrd.h_coin_envelope = *h_blind_ev;
  if (GNUNET_OK !=
      GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_WALLET_RESERVE_WITHDRAW,
                                  &wsrd.purpose,
                                  &reserve_sig->eddsa_signature,
                                  &reserve_pub->eddsa_pub))
  {
    report_row_inconsistency ("reserve_out",
                              rowid,
                              "invalid signature for reserve withdrawal");
    return GNUNET_OK;
  }

  GNUNET_CRYPTO_hash (reserve_pub,
                      sizeof (*reserve_pub),
                      &key);
  rs = GNUNET_CONTAINER_multihashmap_get (rc->reserves,
                                          &key);
  if (NULL == rs)
  {
    rs = GNUNET_new (struct ReserveSummary);
    rs->reserve_pub = *reserve_pub;
    rs->total_out = *amount_with_fee;
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_get_zero (amount_with_fee->currency,
                                          &rs->total_in));
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_get_zero (amount_with_fee->currency,
                                          &rs->total_fee));
    if (GNUNET_OK !=
        load_auditor_reserve_summary (rs))
    {
      GNUNET_break (0);
      GNUNET_free (rs);
      return GNUNET_SYSERR;
    }
    GNUNET_assert (GNUNET_OK ==
                   GNUNET_CONTAINER_multihashmap_put (rc->reserves,
                                                      &key,
                                                      rs,
                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  }
  else
  {
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_add (&rs->total_out,
                                     &rs->total_out,
                                     amount_with_fee));
  }
  GNUNET_assert (rowid >= rs->a_last_reserve_out_serial_id);
  rs->a_last_reserve_out_serial_id = rowid + 1;

  TALER_amount_ntoh (&withdraw_fee,
                     &dki->properties.fee_withdraw);
  GNUNET_assert (GNUNET_OK ==
                 TALER_amount_add (&rs->total_fee,
                                   &rs->total_fee,
                                   &withdraw_fee));

  return GNUNET_OK;
}


/**
 * Check that the reserve summary matches what the exchange database
 * thinks about the reserve, and update our own state of the reserve.
 *
 * Remove all reserves that we are happy with from the DB.
 *
 * @param cls our `struct ReserveContext`
 * @param key hash of the reserve public key
 * @param value a `struct ReserveSummary`
 * @return #GNUNET_OK to process more entries
 */
static int
verify_reserve_balance (void *cls,
                        const struct GNUNET_HashCode *key,
                        void *value)
{
  struct ReserveContext *rc = cls;
  struct ReserveSummary *rs = value;
  struct TALER_EXCHANGEDB_Reserve reserve;
  struct TALER_Amount balance;
  int ret;

  ret = GNUNET_OK;
  reserve.pub = rs->reserve_pub;
  if (GNUNET_OK !=
      edb->reserve_get (edb->cls,
                        esession,
                        &reserve))
  {
    char *diag;

    GNUNET_asprintf (&diag,
                     "Failed to find summary for reserve `%s'\n",
                     TALER_B2S (&rs->reserve_pub));
    report_row_inconsistency ("reserve-summary",
                              UINT64_MAX,
                              diag);
    GNUNET_free (diag);
    return GNUNET_OK;
  }

  if (GNUNET_OK !=
      TALER_amount_add (&balance,
                        &rs->total_in,
                        &rs->a_balance))
  {
    report_reserve_inconsistency (&rs->reserve_pub,
                                  &rs->total_in,
                                  &rs->a_balance,
                                  "could not add old balance to new balance");
    goto cleanup;
  }

  if (GNUNET_SYSERR ==
      TALER_amount_subtract (&balance,
                             &balance,
                             &rs->total_out))
  {
    report_reserve_inconsistency (&rs->reserve_pub,
                                  &rs->total_in,
                                  &rs->total_out,
                                  "available balance insufficient to cover transfers");
    goto cleanup;
  }
  if (0 != TALER_amount_cmp (&balance,
                             &reserve.balance))
  {
    report_reserve_inconsistency (&rs->reserve_pub,
                                  &balance,
                                  &reserve.balance,
                                  "computed balance does not match stored balance");
    goto cleanup;
  }

  if (0 == GNUNET_TIME_absolute_get_remaining (rs->a_expiration_date).rel_value_us)
  {
    /* TODO: handle case where reserve is expired! (#4956) */
    /* NOTE: we may or may not have seen the wire-back transfer at this time,
       as the expiration may have just now happened.
       (That is, after we add the table structures and the logic to track
       such transfers...) */
  }

  if ( (0ULL == balance.value) &&
       (0U == balance.fraction) )
  {
    /* TODO: balance is zero, drop reserve details (and then do not update/insert) */
    if (rs->had_ri)
    {
      ret = adb->del_reserve_info (adb->cls,
                                   asession,
                                   &rs->reserve_pub,
                                   &master_pub);
      if (GNUNET_SYSERR == ret)
      {
        GNUNET_break (0);
        goto cleanup;
      }
      if (GNUNET_NO == ret)
      {
        GNUNET_break (0);
        ret = GNUNET_SYSERR;
        goto cleanup;
      }
    }
    ret = GNUNET_OK;
    goto cleanup;
  }

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Reserve balance `%s' OK\n",
              TALER_B2S (&rs->reserve_pub));

  /* Add withdraw fees we encountered to totals */
  if (GNUNET_YES !=
      TALER_amount_add (&rs->a_withdraw_fee_balance,
                        &rs->a_withdraw_fee_balance,
                        &rs->total_fee))
  {
    GNUNET_break (0);
    ret = GNUNET_SYSERR;
    goto cleanup;
  }
  if (rs->had_ri)
    ret = adb->update_reserve_info (adb->cls,
                                    asession,
                                    &rs->reserve_pub,
                                    &master_pub,
                                    &balance,
                                    &rs->a_withdraw_fee_balance,
                                    rs->a_expiration_date,
                                    rs->a_last_reserve_in_serial_id,
                                    rs->a_last_reserve_out_serial_id);
  else
    ret = adb->insert_reserve_info (adb->cls,
                                    asession,
                                    &rs->reserve_pub,
                                    &master_pub,
                                    &balance,
                                    &rs->a_withdraw_fee_balance,
                                    rs->a_expiration_date,
                                    rs->a_last_reserve_in_serial_id,
                                    rs->a_last_reserve_out_serial_id);

  if ( (GNUNET_YES !=
        TALER_amount_add (&rc->total_balance,
                          &rc->total_balance,
                          &rs->total_in)) ||
       (GNUNET_SYSERR ==
        TALER_amount_subtract (&rc->total_balance,
                               &rc->total_balance,
                               &rs->total_out)) ||
       (GNUNET_YES !=
        TALER_amount_add (&rc->total_fee_balance,
                          &rc->total_fee_balance,
                          &rs->total_fee)) )
  {
    GNUNET_break (0);
    ret = GNUNET_SYSERR;
    goto cleanup;
  }


 cleanup:
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multihashmap_remove (rc->reserves,
                                                       key,
                                                       rs));
  GNUNET_free (rs);
  return ret;
}


/**
 * Analyze reserves for being well-formed.
 *
 * @param cls NULL
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on invariant violation
 */
static int
analyze_reserves (void *cls)
{
  struct ReserveContext rc;
  int ret;

  ret = adb->get_reserve_summary (adb->cls,
                                  asession,
                                  &master_pub,
                                  &rc.total_balance,
                                  &rc.total_fee_balance);
  if (GNUNET_SYSERR == ret)
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }

  rc.reserves = GNUNET_CONTAINER_multihashmap_create (512,
                                                      GNUNET_NO);

  if (GNUNET_OK !=
      edb->select_reserves_in_above_serial_id (edb->cls,
                                               esession,
                                               pp.last_reserve_in_serial_id,
                                               &handle_reserve_in,
                                               &rc))
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  if (GNUNET_OK !=
      edb->select_reserves_out_above_serial_id (edb->cls,
                                                esession,
                                                pp.last_reserve_out_serial_id,
                                                &handle_reserve_out,
                                                &rc))
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  /* TODO: iterate over table for reserve expiration refunds! (#4956) */

  GNUNET_CONTAINER_multihashmap_iterate (rc.reserves,
                                         &verify_reserve_balance,
                                         &rc);
  GNUNET_break (0 ==
                GNUNET_CONTAINER_multihashmap_size (rc.reserves));
  GNUNET_CONTAINER_multihashmap_destroy (rc.reserves);


  if (GNUNET_NO == ret)
  {
    ret = adb->insert_reserve_summary (adb->cls,
                                       asession,
                                       &master_pub,
                                       &rc.total_balance,
                                       &rc.total_fee_balance);
  }
  else
  {
    ret = adb->update_reserve_summary (adb->cls,
                                       asession,
                                       &master_pub,
                                       &rc.total_balance,
                                       &rc.total_fee_balance);
  }
  report_reserve_balance (&rc.total_balance,
                          &rc.total_fee_balance);
  return GNUNET_OK;
}


/* ************************* Analyze coins ******************** */
/* This logic checks that the exchange did the right thing for each
   coin, checking deposits, refunds, refresh* and known_coins
   tables */

/* TODO! */
/**
 * Summary data we keep per coin.
 */
struct CoinSummary
{
  /**
   * Denomination of the coin with fee structure.
   */
  struct TALER_EXCHANGEDB_DenominationKeyInformationP *dki;

  /**
   * Public key of the coin.
   */
  struct TALER_CoinSpendPublicKeyP coin_pub;

  /**
   * Total value lost of the coin (deposits, refreshs and fees minus refunds).
   * Must be smaller than the coin's total (origional) value.
   */
  struct TALER_Amount spent;

};


/**
 * Summary data we keep per denomination.
 */
struct DenominationSummary
{
  /**
   * Total value of coins issued with this denomination key.
   */
  struct TALER_Amount denom_balance;

  /**
   * Total amount of deposit fees made.
   */
  struct TALER_Amount deposit_fee_balance;

  /**
   * Total amount of melt fees made.
   */
  struct TALER_Amount melt_fee_balance;

  /**
   * Total amount of refund fees made.
   */
  struct TALER_Amount refund_fee_balance;

  /**
   * Up to which point have we processed reserves_out?
   */
  uint64_t last_reserve_out_serial_id;

  /**
   * Up to which point have we processed deposits?
   */
  uint64_t last_deposit_serial_id;

  /**
   * Up to which point have we processed melts?
   */
  uint64_t last_melt_serial_id;

  /**
   * Up to which point have we processed refunds?
   */
  uint64_t last_refund_serial_id;
};


/**
 * Closure for callbacks during #analyze_coins().
 */
struct CoinContext
{

  /**
   * Map for tracking information about coins.
   */
  struct GNUNET_CONTAINER_MultiHashMap *coins;

  /**
   * Map for tracking information about denominations.
   */
  struct GNUNET_CONTAINER_MultiHashMap *denominations;

};


/**
 * Analyze the exchange's processing of coins.
 *
 * @param cls closure
 * @param int #GNUNET_OK on success, #GNUNET_SYSERR on hard errors
 */
static int
analyze_coins (void *cls)
{
  struct CoinContext cc;

  cc.coins = GNUNET_CONTAINER_multihashmap_create (1024,
                                                   GNUNET_YES);
  cc.denominations = GNUNET_CONTAINER_multihashmap_create (256,
                                                           GNUNET_YES);


  GNUNET_CONTAINER_multihashmap_destroy (cc.denominations);
  GNUNET_CONTAINER_multihashmap_destroy (cc.coins);

  return GNUNET_OK;
}


/* ************************* Analyze merchants ******************** */
/* This logic checks that the aggregator did the right thing
   paying each merchant what they were due (and on time). */


/**
 * Summary data we keep per merchant.
 */
struct MerchantSummary
{

  /**
   * Which account were we supposed to pay?
   */
  struct GNUNET_HashCode h_wire;

  /**
   * Total due to be paid to @e h_wire.
   */
  struct TALER_Amount total_due;

  /**
   * Total paid to @e h_wire.
   */
  struct TALER_Amount total_paid;

  /**
   * Total wire fees charged.
   */
  struct TALER_Amount total_fees;

  /**
   * Last (expired) refund deadline of all the transactions totaled
   * up in @e due.
   */
  struct GNUNET_TIME_Absolute last_refund_deadline;

};


/**
 * Closure for callbacks during #analyze_merchants().
 */
struct MerchantContext
{

  /**
   * Map for tracking information about merchants.
   */
  struct GNUNET_CONTAINER_MultiHashMap *merchants;

};


/**
 * Analyze the exchange aggregator's payment processing.
 *
 * @param cls closure
 * @param int #GNUNET_OK on success, #GNUNET_SYSERR on hard errors
 */
static int
analyze_merchants (void *cls)
{
  struct MerchantContext mc;

  mc.merchants = GNUNET_CONTAINER_multihashmap_create (1024,
                                                       GNUNET_YES);

  // TODO

  GNUNET_CONTAINER_multihashmap_destroy (mc.merchants);
  return GNUNET_OK;
}


/* *************************** General transaction logic ****************** */

/**
 * Type of an analysis function.  Each analysis function runs in
 * its own transaction scope and must thus be internally consistent.
 *
 * @param cls closure
 * @param int #GNUNET_OK on success, #GNUNET_SYSERR on hard errors
 */
typedef int
(*Analysis)(void *cls);


/**
 * Perform the given @a analysis incrementally, checkpointing our
 * progress in the auditor DB.
 *
 * @param analysis analysis to run
 * @param analysis_cls closure for @a analysis
 * @return #GNUNET_OK if @a analysis succeessfully committed,
 *         #GNUNET_SYSERR on hard errors
 */
static int
incremental_processing (Analysis analysis,
                        void *analysis_cls)
{
  int ret;

  ret = adb->get_auditor_progress (adb->cls,
                                   asession,
                                   &master_pub,
                                   &pp);
  if (GNUNET_SYSERR == ret)
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  if (GNUNET_NO == ret)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_MESSAGE,
                  _("First analysis using this auditor, starting audit from scratch\n"));
    }
  else
    {
      GNUNET_log (GNUNET_ERROR_TYPE_MESSAGE,
                  _("Resuming audit at %llu/%llu/%llu/%llu/%llu/%llu\n\n"),
                  (unsigned long long) pp.last_reserve_in_serial_id,
                  (unsigned long long) pp.last_reserve_out_serial_id,
                  (unsigned long long) pp.last_deposit_serial_id,
                  (unsigned long long) pp.last_melt_serial_id,
                  (unsigned long long) pp.last_refund_serial_id,
                  (unsigned long long) pp.last_prewire_serial_id);
    }
  ret = analysis (analysis_cls);
  if (GNUNET_OK != ret)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Analysis phase failed, not recording progress\n");
      return GNUNET_SYSERR;
    }
  ret = adb->update_auditor_progress (adb->cls,
                                      asession,
                                      &master_pub,
                                      &pp);
  if (GNUNET_OK != ret)
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  GNUNET_log (GNUNET_ERROR_TYPE_MESSAGE,
              _("Resuming audit at %llu/%llu/%llu/%llu/%llu/%llu\n\n"),
              (unsigned long long) pp.last_reserve_in_serial_id,
              (unsigned long long) pp.last_reserve_out_serial_id,
              (unsigned long long) pp.last_deposit_serial_id,
              (unsigned long long) pp.last_melt_serial_id,
              (unsigned long long) pp.last_refund_serial_id,
              (unsigned long long) pp.last_prewire_serial_id);
  return GNUNET_OK;
}


/**
 * Perform the given @a analysis within a transaction scope.
 * Commit on success.
 *
 * @param analysis analysis to run
 * @param analysis_cls closure for @a analysis
 * @return #GNUNET_OK if @a analysis succeessfully committed,
 *         #GNUNET_NO if we had an error on commit (retry may help)
 *         #GNUNET_SYSERR on hard errors
 */
static int
transact (Analysis analysis,
          void *analysis_cls)
{
  int ret;

  ret = adb->start (adb->cls,
                    asession);
  if (GNUNET_OK != ret)
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  ret = edb->start (edb->cls,
                    esession);
  if (GNUNET_OK != ret)
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  ret = incremental_processing (analysis,
                                analysis_cls);
  if (GNUNET_OK == ret)
    {
      ret = edb->commit (edb->cls,
                         esession);
      if (GNUNET_OK != ret)
        {
          GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                      "Exchange DB commit failed, rolling back transaction\n");
          adb->rollback (adb->cls,
                         asession);
        }
      else
        {
          ret = adb->commit (adb->cls,
                             asession);
          if (GNUNET_OK != ret)
            {
              GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                          "Auditor DB commit failed!\n");
            }
        }
    }
  else
    {
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Processing failed, rolling back transaction\n");
      adb->rollback (adb->cls,
                     asession);
      edb->rollback (edb->cls,
                     esession);
    }
  clear_transaction_state_cache ();
  return ret;
}


/**
 * Initialize DB sessions and run the analysis.
 */
static void
setup_sessions_and_run ()
{
  esession = edb->get_session (edb->cls);
  if (NULL == esession)
  {
    fprintf (stderr,
             "Failed to initialize exchange session.\n");
    global_ret = 1;
    return;
  }
  asession = adb->get_session (adb->cls);
  if (NULL == asession)
  {
    fprintf (stderr,
             "Failed to initialize auditor session.\n");
    global_ret = 1;
    return;
  }

  transact (&analyze_reserves,
            NULL);
  transact (&analyze_coins,
            NULL);
  transact (&analyze_merchants,
            NULL);
}


/**
 * 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 cfg configuration
 */
static void
run (void *cls,
     char *const *args,
     const char *cfgfile,
     const struct GNUNET_CONFIGURATION_Handle *cfg)
{
  if (NULL ==
      (edb = TALER_EXCHANGEDB_plugin_load (cfg)))
  {
    fprintf (stderr,
             "Failed to initialize exchange database plugin.\n");
    global_ret = 1;
    return;
  }
  if (NULL ==
      (adb = TALER_AUDITORDB_plugin_load (cfg)))
  {
    fprintf (stderr,
             "Failed to initialize auditor database plugin.\n");
    global_ret = 1;
    TALER_EXCHANGEDB_plugin_unload (edb);
    return;
  }
  setup_sessions_and_run ();
  TALER_AUDITORDB_plugin_unload (adb);
  TALER_EXCHANGEDB_plugin_unload (edb);
}


/**
 * The main function of the database initialization tool.
 * Used to initialize the Taler Exchange's database.
 *
 * @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)
{
  const struct GNUNET_GETOPT_CommandLineOption options[] = {
    GNUNET_GETOPT_OPTION_MANDATORY
    (GNUNET_GETOPT_OPTION_SET_BASE32_AUTO ('m',
                                           "exchange-key",
                                           "KEY",
                                           "public key of the exchange (Crockford base32 encoded)",
                                           &master_pub)),
    GNUNET_GETOPT_OPTION_END
  };

  /* force linker to link against libtalerutil; if we do
     not do this, the linker may "optimize" libtalerutil
     away and skip #TALER_OS_init(), which we do need */
  (void) TALER_project_data_default ();
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_log_setup ("taler-auditor",
                                   "INFO",
                                   NULL));
  if (GNUNET_OK !=
      GNUNET_PROGRAM_run (argc,
			  argv,
                          "taler-auditor",
			  "Audit Taler exchange database",
			  options,
			  &run,
			  NULL))
    return 1;
  return global_ret;
}


/* end of taler-auditor.c */