path: root/src/exchange/taler-exchange-httpd_batch-withdraw.c

/*
  This file is part of TALER
  Copyright (C) 2014-2023 Taler Systems SA

  TALER 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,
  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 Affero General Public License for more details.

  You should have received a copy of the GNU Affero General
  Public License along with TALER; see the file COPYING.  If not,
  see <http://www.gnu.org/licenses/>
*/
/**
 * @file taler-exchange-httpd_batch-withdraw.c
 * @brief Handle /reserves/$RESERVE_PUB/batch-withdraw requests
 * @author Florian Dold
 * @author Benedikt Mueller
 * @author Christian Grothoff
 */
#include "platform.h"
#include <gnunet/gnunet_util_lib.h>
#include <jansson.h>
#include "taler-exchange-httpd.h"
#include "taler_json_lib.h"
#include "taler_kyclogic_lib.h"
#include "taler_mhd_lib.h"
#include "taler-exchange-httpd_batch-withdraw.h"
#include "taler-exchange-httpd_responses.h"
#include "taler-exchange-httpd_keys.h"
#include "taler_util.h"


/**
 * Information per planchet in the batch.
 */
struct PlanchetContext
{

  /**
   * Hash of the (blinded) message to be signed by the Exchange.
   */
  struct TALER_BlindedCoinHashP h_coin_envelope;

  /**
   * Value of the coin being exchanged (matching the denomination key)
   * plus the transaction fee.  We include this in what is being
   * signed so that we can verify a reserve's remaining total balance
   * without needing to access the respective denomination key
   * information each time.
   */
  struct TALER_Amount amount_with_fee;

  /**
   * Blinded planchet.
   */
  struct TALER_BlindedPlanchet blinded_planchet;

  /**
   * Set to the resulting signed coin data to be returned to the client.
   */
  struct TALER_EXCHANGEDB_CollectableBlindcoin collectable;

};

/**
 * Context for #batch_withdraw_transaction.
 */
struct BatchWithdrawContext
{

  /**
   * Public key of the reserve.
   */
  const struct TALER_ReservePublicKeyP *reserve_pub;

  /**
   * request context
   */
  const struct TEH_RequestContext *rc;

  /**
   * KYC status of the reserve used for the operation.
   */
  struct TALER_EXCHANGEDB_KycStatus kyc;

  /**
   * Array of @e planchets_length planchets we are processing.
   */
  struct PlanchetContext *planchets;

  /**
   * Hash of the payto-URI representing the reserve
   * from which we are withdrawing.
   */
  struct TALER_PaytoHashP h_payto;

  /**
   * Current time for the DB transaction.
   */
  struct GNUNET_TIME_Timestamp now;

  /**
   * Total amount from all coins with fees.
   */
  struct TALER_Amount batch_total;

  /**
   * Length of the @e planchets array.
   */
  unsigned int planchets_length;

  /**
   * AML decision, #TALER_AML_NORMAL if we may proceed.
   */
  enum TALER_AmlDecisionState aml_decision;

};


/**
 * Function called to iterate over KYC-relevant
 * transaction amounts for a particular time range.
 * Called within a database transaction, so must
 * not start a new one.
 *
 * @param cls closure, identifies the event type and
 *        account to iterate over events for
 * @param limit maximum time-range for which events
 *        should be fetched (timestamp in the past)
 * @param cb function to call on each event found,
 *        events must be returned in reverse chronological
 *        order
 * @param cb_cls closure for @a cb
 */
static void
batch_withdraw_amount_cb (void *cls,
                          struct GNUNET_TIME_Absolute limit,
                          TALER_EXCHANGEDB_KycAmountCallback cb,
                          void *cb_cls)
{
  struct BatchWithdrawContext *wc = cls;
  enum GNUNET_DB_QueryStatus qs;

  if (GNUNET_OK !=
      cb (cb_cls,
          &wc->batch_total,
          wc->now.abs_time))
    return;
  qs = TEH_plugin->select_withdraw_amounts_for_kyc_check (
    TEH_plugin->cls,
    &wc->h_payto,
    limit,
    cb,
    cb_cls);
  GNUNET_break (qs >= 0);
}


/**
 * Function called on each @a amount that was found to
 * be relevant for the AML check as it was merged into
 * the reserve.
 *
 * @param cls `struct TALER_Amount *` to total up the amounts
 * @param amount encountered transaction amount
 * @param date when was the amount encountered
 * @return #GNUNET_OK to continue to iterate,
 *         #GNUNET_NO to abort iteration
 *         #GNUNET_SYSERR on internal error (also abort itaration)
 */
static enum GNUNET_GenericReturnValue
aml_amount_cb (
  void *cls,
  const struct TALER_Amount *amount,
  struct GNUNET_TIME_Absolute date)
{
  struct TALER_Amount *total = cls;

  GNUNET_assert (0 <=
                 TALER_amount_add (total,
                                   total,
                                   amount));
  return GNUNET_OK;
}


/**
 * Generates our final (successful) response.
 *
 * @param rc request context
 * @param wc operation context
 * @return MHD queue status
 */
static MHD_RESULT
generate_reply_success (const struct TEH_RequestContext *rc,
                        const struct BatchWithdrawContext *wc)
{
  json_t *sigs;

  if (! wc->kyc.ok)
  {
    /* KYC required */
    return TEH_RESPONSE_reply_kyc_required (rc->connection,
                                            &wc->h_payto,
                                            &wc->kyc);
  }
  if (TALER_AML_NORMAL != wc->aml_decision)
    return TEH_RESPONSE_reply_aml_blocked (rc->connection,
                                           wc->aml_decision);

  sigs = json_array ();
  GNUNET_assert (NULL != sigs);
  for (unsigned int i = 0; i<wc->planchets_length; i++)
  {
    struct PlanchetContext *pc = &wc->planchets[i];

    GNUNET_assert (
      0 ==
      json_array_append_new (
        sigs,
        GNUNET_JSON_PACK (
          TALER_JSON_pack_blinded_denom_sig (
            "ev_sig",
            &pc->collectable.sig))));
  }
  TEH_METRICS_batch_withdraw_num_coins += wc->planchets_length;
  return TALER_MHD_REPLY_JSON_PACK (
    rc->connection,
    MHD_HTTP_OK,
    GNUNET_JSON_pack_array_steal ("ev_sigs",
                                  sigs));
}


/**
 * Check if the @a wc is replayed and we already have an
 * answer. If so, replay the existing answer and return the
 * HTTP response.
 *
 * @param wc parsed request data
 * @param[out] mret HTTP status, set if we return true
 * @return true if the request is idempotent with an existing request
 *    false if we did not find the request in the DB and did not set @a mret
 */
static bool
check_request_idempotent (const struct BatchWithdrawContext *wc,
                          MHD_RESULT *mret)
{
  const struct TEH_RequestContext *rc = wc->rc;

  for (unsigned int i = 0; i<wc->planchets_length; i++)
  {
    struct PlanchetContext *pc = &wc->planchets[i];
    enum GNUNET_DB_QueryStatus qs;

    qs = TEH_plugin->get_withdraw_info (TEH_plugin->cls,
                                        &pc->h_coin_envelope,
                                        &pc->collectable);
    if (0 > qs)
    {
      GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
      if (GNUNET_DB_STATUS_HARD_ERROR == qs)
        *mret = TALER_MHD_reply_with_error (rc->connection,
                                            MHD_HTTP_INTERNAL_SERVER_ERROR,
                                            TALER_EC_GENERIC_DB_FETCH_FAILED,
                                            "get_withdraw_info");
      return true; /* well, kind-of */
    }
    if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
      return false;
  }
  /* generate idempotent reply */
  TEH_METRICS_num_requests[TEH_MT_REQUEST_IDEMPOTENT_BATCH_WITHDRAW]++;
  *mret = generate_reply_success (rc,
                                  wc);
  return true;
}


/**
 * Function implementing withdraw transaction.  Runs the
 * transaction logic; IF it returns a non-error code, the transaction
 * logic MUST NOT queue a MHD response.  IF it returns an hard error,
 * the transaction logic MUST queue a MHD response and set @a mhd_ret.
 * IF it returns the soft error code, the function MAY be called again
 * to retry and MUST not queue a MHD response.
 *
 * Note that "wc->collectable.sig" is set before entering this function as we
 * signed before entering the transaction.
 *
 * @param cls a `struct BatchWithdrawContext *`
 * @param connection MHD request which triggered the transaction
 * @param[out] mhd_ret set to MHD response status for @a connection,
 *             if transaction failed (!)
 * @return transaction status
 */
static enum GNUNET_DB_QueryStatus
batch_withdraw_transaction (void *cls,
                            struct MHD_Connection *connection,
                            MHD_RESULT *mhd_ret)
{
  struct BatchWithdrawContext *wc = cls;
  uint64_t ruuid;
  enum GNUNET_DB_QueryStatus qs;
  bool found = false;
  bool balance_ok = false;
  bool age_ok = false;
  uint16_t allowed_maximum_age = 0;
  struct TALER_Amount reserve_balance;
  char *kyc_required;
  struct TALER_PaytoHashP reserve_h_payto;

  wc->now = GNUNET_TIME_timestamp_get ();
  /* Do AML check: compute total merged amount and check
     against applicable AML threshold */
  {
    char *reserve_payto;

    reserve_payto = TALER_reserve_make_payto (TEH_base_url,
                                              wc->reserve_pub);
    TALER_payto_hash (reserve_payto,
                      &reserve_h_payto);
    GNUNET_free (reserve_payto);
  }
  {
    struct TALER_Amount merge_amount;
    struct TALER_Amount threshold;
    struct GNUNET_TIME_Absolute now_minus_one_month;

    now_minus_one_month
      = GNUNET_TIME_absolute_subtract (wc->now.abs_time,
                                       GNUNET_TIME_UNIT_MONTHS);
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_set_zero (TEH_currency,
                                          &merge_amount));
    qs = TEH_plugin->select_merge_amounts_for_kyc_check (TEH_plugin->cls,
                                                         &reserve_h_payto,
                                                         now_minus_one_month,
                                                         &aml_amount_cb,
                                                         &merge_amount);
    if (qs < 0)
    {
      GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
      if (GNUNET_DB_STATUS_HARD_ERROR == qs)
        *mhd_ret = TALER_MHD_reply_with_error (connection,
                                               MHD_HTTP_INTERNAL_SERVER_ERROR,
                                               TALER_EC_GENERIC_DB_FETCH_FAILED,
                                               "select_merge_amounts_for_kyc_check");
      return qs;
    }
    qs = TEH_plugin->select_aml_threshold (TEH_plugin->cls,
                                           &reserve_h_payto,
                                           &wc->aml_decision,
                                           &wc->kyc,
                                           &threshold);
    if (qs < 0)
    {
      GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
      if (GNUNET_DB_STATUS_HARD_ERROR == qs)
        *mhd_ret = TALER_MHD_reply_with_error (connection,
                                               MHD_HTTP_INTERNAL_SERVER_ERROR,
                                               TALER_EC_GENERIC_DB_FETCH_FAILED,
                                               "select_aml_threshold");
      return qs;
    }
    if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
    {
      threshold = TEH_aml_threshold; /* use default */
      wc->aml_decision = TALER_AML_NORMAL;
    }

    switch (wc->aml_decision)
    {
    case TALER_AML_NORMAL:
      if (0 >= TALER_amount_cmp (&merge_amount,
                                 &threshold))
      {
        /* merge_amount <= threshold, continue withdraw below */
        break;
      }
      wc->aml_decision = TALER_AML_PENDING;
      qs = TEH_plugin->trigger_aml_process (TEH_plugin->cls,
                                            &reserve_h_payto,
                                            &merge_amount);
      if (qs <= 0)
      {
        GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
        if (GNUNET_DB_STATUS_HARD_ERROR == qs)
          *mhd_ret = TALER_MHD_reply_with_error (connection,
                                                 MHD_HTTP_INTERNAL_SERVER_ERROR,
                                                 TALER_EC_GENERIC_DB_STORE_FAILED,
                                                 "trigger_aml_process");
        return qs;
      }
      return qs;
    case TALER_AML_PENDING:
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "AML already pending, doing nothing\n");
      return qs;
    case TALER_AML_FROZEN:
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  "Account frozen, doing nothing\n");
      return qs;
    }
  }

  /* Check if the money came from a wire transfer */
  qs = TEH_plugin->reserves_get_origin (TEH_plugin->cls,
                                        wc->reserve_pub,
                                        &wc->h_payto);
  if (qs < 0)
  {
    if (GNUNET_DB_STATUS_HARD_ERROR == qs)
      *mhd_ret = TALER_MHD_reply_with_error (connection,
                                             MHD_HTTP_INTERNAL_SERVER_ERROR,
                                             TALER_EC_GENERIC_DB_FETCH_FAILED,
                                             "reserves_get_origin");
    return qs;
  }
  /* If no results, reserve was created by merge, in which case no KYC check
     is required as the merge already did that. */
  if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs)
  {
    qs = TALER_KYCLOGIC_kyc_test_required (
      TALER_KYCLOGIC_KYC_TRIGGER_WITHDRAW,
      &wc->h_payto,
      TEH_plugin->select_satisfied_kyc_processes,
      TEH_plugin->cls,
      &batch_withdraw_amount_cb,
      wc,
      &kyc_required);
    if (qs < 0)
    {
      GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
      if (GNUNET_DB_STATUS_HARD_ERROR == qs)
        *mhd_ret = TALER_MHD_reply_with_error (connection,
                                               MHD_HTTP_INTERNAL_SERVER_ERROR,
                                               TALER_EC_GENERIC_DB_FETCH_FAILED,
                                               "kyc_test_required");
      return qs;
    }
    if (NULL != kyc_required)
    {
      /* insert KYC requirement into DB! */
      wc->kyc.ok = false;
      qs = TEH_plugin->insert_kyc_requirement_for_account (
        TEH_plugin->cls,
        kyc_required,
        &wc->h_payto,
        wc->reserve_pub,
        &wc->kyc.requirement_row);
      GNUNET_free (kyc_required);
      if (qs < 0)
      {
        GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
        if (GNUNET_DB_STATUS_HARD_ERROR == qs)
          *mhd_ret = TALER_MHD_reply_with_error (connection,
                                                 MHD_HTTP_INTERNAL_SERVER_ERROR,
                                                 TALER_EC_GENERIC_DB_STORE_FAILED,
                                                 "insert_kyc_requirement_for_account");
      }
      return qs;
    }
  }
  wc->kyc.ok = true;

  qs = TEH_plugin->do_batch_withdraw (TEH_plugin->cls,
                                      wc->now,
                                      wc->reserve_pub,
                                      &wc->batch_total,
                                      TEH_age_restriction_enabled,
                                      &found,
                                      &balance_ok,
                                      &reserve_balance,
                                      &age_ok,
                                      &allowed_maximum_age,
                                      &ruuid);
  if (0 > qs)
  {
    if (GNUNET_DB_STATUS_HARD_ERROR == qs)
    {
      GNUNET_break (0);
      *mhd_ret = TALER_MHD_reply_with_error (connection,
                                             MHD_HTTP_INTERNAL_SERVER_ERROR,
                                             TALER_EC_GENERIC_DB_FETCH_FAILED,
                                             "update_reserve_batch_withdraw");
    }
    return qs;
  }
  if (! found)
  {
    *mhd_ret = TALER_MHD_reply_with_error (connection,
                                           MHD_HTTP_NOT_FOUND,
                                           TALER_EC_EXCHANGE_GENERIC_RESERVE_UNKNOWN,
                                           NULL);
    return GNUNET_DB_STATUS_HARD_ERROR;
  }

  if (! age_ok)
  {
    /* We respond with the lowest age in the corresponding age group
     * of the required age */
    uint16_t lowest_age = TALER_get_lowest_age (
      &TEH_age_restriction_config.mask,
      allowed_maximum_age);

    TEH_plugin->rollback (TEH_plugin->cls);
    *mhd_ret = TEH_RESPONSE_reply_reserve_age_restriction_required (
      connection,
      lowest_age);
    return GNUNET_DB_STATUS_HARD_ERROR;
  }

  if (! balance_ok)
  {
    TEH_plugin->rollback (TEH_plugin->cls);
    *mhd_ret = TEH_RESPONSE_reply_reserve_insufficient_balance (
      connection,
      TALER_EC_EXCHANGE_WITHDRAW_INSUFFICIENT_FUNDS,
      &reserve_balance,
      &wc->batch_total,
      wc->reserve_pub);
    return GNUNET_DB_STATUS_HARD_ERROR;
  }

  /* Add information about each planchet in the batch */
  for (unsigned int i = 0; i<wc->planchets_length; i++)
  {
    struct PlanchetContext *pc = &wc->planchets[i];
    const struct TALER_BlindedPlanchet *bp = &pc->blinded_planchet;
    const union GNUNET_CRYPTO_BlindSessionNonce *nonce = NULL;
    bool denom_unknown = true;
    bool conflict = true;
    bool nonce_reuse = true;

    switch (bp->blinded_message->cipher)
    {
    case GNUNET_CRYPTO_BSA_INVALID:
      break;
    case GNUNET_CRYPTO_BSA_RSA:
      break;
    case GNUNET_CRYPTO_BSA_CS:
      nonce = (const union GNUNET_CRYPTO_BlindSessionNonce *)
              &bp->blinded_message->details.cs_blinded_message.nonce;
      break;
    }
    qs = TEH_plugin->do_batch_withdraw_insert (TEH_plugin->cls,
                                               nonce,
                                               &pc->collectable,
                                               wc->now,
                                               ruuid,
                                               &denom_unknown,
                                               &conflict,
                                               &nonce_reuse);
    if (0 > qs)
    {
      if (GNUNET_DB_STATUS_HARD_ERROR == qs)
        *mhd_ret = TALER_MHD_reply_with_error (connection,
                                               MHD_HTTP_INTERNAL_SERVER_ERROR,
                                               TALER_EC_GENERIC_DB_FETCH_FAILED,
                                               "do_batch_withdraw_insert");
      return qs;
    }
    if (denom_unknown)
    {
      GNUNET_break (0);
      *mhd_ret = TALER_MHD_reply_with_error (connection,
                                             MHD_HTTP_INTERNAL_SERVER_ERROR,
                                             TALER_EC_GENERIC_DB_INVARIANT_FAILURE,
                                             NULL);
      return GNUNET_DB_STATUS_HARD_ERROR;
    }
    if ( (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs) ||
         (conflict) )
    {
      if (! check_request_idempotent (wc,
                                      mhd_ret))
      {
        /* We do not support *some* of the coins of the request being
           idempotent while others being fresh. */
        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                    "Idempotent coin in batch, not allowed. Aborting.\n");
        *mhd_ret = TALER_MHD_reply_with_error (connection,
                                               MHD_HTTP_CONFLICT,
                                               TALER_EC_EXCHANGE_WITHDRAW_BATCH_IDEMPOTENT_PLANCHET,
                                               NULL);
      }
      return GNUNET_DB_STATUS_HARD_ERROR;
    }
    if (nonce_reuse)
    {
      GNUNET_break_op (0);
      *mhd_ret = TALER_MHD_reply_with_error (connection,
                                             MHD_HTTP_BAD_REQUEST,
                                             TALER_EC_EXCHANGE_WITHDRAW_NONCE_REUSE,
                                             NULL);
      return GNUNET_DB_STATUS_HARD_ERROR;
    }
  }
  TEH_METRICS_num_success[TEH_MT_SUCCESS_BATCH_WITHDRAW]++;
  return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT;
}


/**
 * The request was parsed successfully. Prepare
 * our side for the main DB transaction.
 *
 * @param rc request details
 * @param wc storage for request processing
 * @return MHD result for the @a rc
 */
static MHD_RESULT
prepare_transaction (const struct TEH_RequestContext *rc,
                     struct BatchWithdrawContext *wc)
{
  struct TEH_CoinSignData csds[wc->planchets_length];
  struct TALER_BlindedDenominationSignature bss[wc->planchets_length];

  for (unsigned int i = 0; i<wc->planchets_length; i++)
  {
    struct PlanchetContext *pc = &wc->planchets[i];

    csds[i].h_denom_pub = &pc->collectable.denom_pub_hash;
    csds[i].bp = &pc->blinded_planchet;
  }
  {
    enum TALER_ErrorCode ec;

    ec = TEH_keys_denomination_batch_sign (
      wc->planchets_length,
      csds,
      false,
      bss);
    if (TALER_EC_NONE != ec)
    {
      GNUNET_break (0);
      return TALER_MHD_reply_with_ec (rc->connection,
                                      ec,
                                      NULL);
    }
  }
  for (unsigned int i = 0; i<wc->planchets_length; i++)
  {
    struct PlanchetContext *pc = &wc->planchets[i];

    pc->collectable.sig = bss[i];
  }

  /* run transaction */
  {
    MHD_RESULT mhd_ret;

    if (GNUNET_OK !=
        TEH_DB_run_transaction (rc->connection,
                                "run batch withdraw",
                                TEH_MT_REQUEST_WITHDRAW,
                                &mhd_ret,
                                &batch_withdraw_transaction,
                                wc))
    {
      return mhd_ret;
    }
  }
  /* return final positive response */
  return generate_reply_success (rc,
                                 wc);
}


/**
 * Continue processing the request @a rc by parsing the
 * @a planchets and then running the transaction.
 *
 * @param rc request details
 * @param wc storage for request processing
 * @param planchets array of planchets to parse
 * @return MHD result for the @a rc
 */
static MHD_RESULT
parse_planchets (const struct TEH_RequestContext *rc,
                 struct BatchWithdrawContext *wc,
                 const json_t *planchets)
{
  struct TEH_KeyStateHandle *ksh;
  MHD_RESULT mret;

  for (unsigned int i = 0; i<wc->planchets_length; i++)
  {
    struct PlanchetContext *pc = &wc->planchets[i];
    struct GNUNET_JSON_Specification ispec[] = {
      GNUNET_JSON_spec_fixed_auto ("reserve_sig",
                                   &pc->collectable.reserve_sig),
      GNUNET_JSON_spec_fixed_auto ("denom_pub_hash",
                                   &pc->collectable.denom_pub_hash),
      TALER_JSON_spec_blinded_planchet ("coin_ev",
                                        &pc->blinded_planchet),
      GNUNET_JSON_spec_end ()
    };

    {
      enum GNUNET_GenericReturnValue res;

      res = TALER_MHD_parse_json_data (rc->connection,
                                       json_array_get (planchets,
                                                       i),
                                       ispec);
      if (GNUNET_OK != res)
        return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
    }
    pc->collectable.reserve_pub = *wc->reserve_pub;
    for (unsigned int k = 0; k<i; k++)
    {
      const struct PlanchetContext *kpc = &wc->planchets[k];

      if (0 ==
          TALER_blinded_planchet_cmp (&kpc->blinded_planchet,
                                      &pc->blinded_planchet))
      {
        GNUNET_break_op (0);
        return TALER_MHD_reply_with_error (rc->connection,
                                           MHD_HTTP_BAD_REQUEST,
                                           TALER_EC_GENERIC_PARAMETER_MALFORMED,
                                           "duplicate planchet");
      }
    }
  }

  ksh = TEH_keys_get_state ();
  if (NULL == ksh)
  {
    if (! check_request_idempotent (wc,
                                    &mret))
    {
      return TALER_MHD_reply_with_error (rc->connection,
                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                                         TALER_EC_EXCHANGE_GENERIC_KEYS_MISSING,
                                         NULL);
    }
    return mret;
  }
  for (unsigned int i = 0; i<wc->planchets_length; i++)
  {
    struct PlanchetContext *pc = &wc->planchets[i];
    struct TEH_DenominationKey *dk;

    dk = TEH_keys_denomination_by_hash_from_state (
      ksh,
      &pc->collectable.denom_pub_hash,
      NULL,
      NULL);

    if (NULL == dk)
    {
      if (! check_request_idempotent (wc,
                                      &mret))
      {
        return TEH_RESPONSE_reply_unknown_denom_pub_hash (
          rc->connection,
          &pc->collectable.denom_pub_hash);
      }
      return mret;
    }
    if (GNUNET_TIME_absolute_is_past (dk->meta.expire_withdraw.abs_time))
    {
      /* This denomination is past the expiration time for withdraws */
      if (! check_request_idempotent (wc,
                                      &mret))
      {
        return TEH_RESPONSE_reply_expired_denom_pub_hash (
          rc->connection,
          &pc->collectable.denom_pub_hash,
          TALER_EC_EXCHANGE_GENERIC_DENOMINATION_EXPIRED,
          "WITHDRAW");
      }
      return mret;
    }
    if (GNUNET_TIME_absolute_is_future (dk->meta.start.abs_time))
    {
      /* This denomination is not yet valid, no need to check
         for idempotency! */
      return TEH_RESPONSE_reply_expired_denom_pub_hash (
        rc->connection,
        &pc->collectable.denom_pub_hash,
        TALER_EC_EXCHANGE_GENERIC_DENOMINATION_VALIDITY_IN_FUTURE,
        "WITHDRAW");
    }
    if (dk->recoup_possible)
    {
      /* This denomination has been revoked */
      if (! check_request_idempotent (wc,
                                      &mret))
      {
        return TEH_RESPONSE_reply_expired_denom_pub_hash (
          rc->connection,
          &pc->collectable.denom_pub_hash,
          TALER_EC_EXCHANGE_GENERIC_DENOMINATION_REVOKED,
          "WITHDRAW");
      }
      return mret;
    }
    if (dk->denom_pub.bsign_pub_key->cipher !=
        pc->blinded_planchet.blinded_message->cipher)
    {
      /* denomination cipher and blinded planchet cipher not the same */
      GNUNET_break_op (0);
      return TALER_MHD_reply_with_error (rc->connection,
                                         MHD_HTTP_BAD_REQUEST,
                                         TALER_EC_EXCHANGE_GENERIC_CIPHER_MISMATCH,
                                         NULL);
    }
    if (0 >
        TALER_amount_add (&pc->collectable.amount_with_fee,
                          &dk->meta.value,
                          &dk->meta.fees.withdraw))
    {
      GNUNET_break (0);
      return TALER_MHD_reply_with_error (rc->connection,
                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                                         TALER_EC_EXCHANGE_WITHDRAW_AMOUNT_FEE_OVERFLOW,
                                         NULL);
    }
    if (0 >
        TALER_amount_add (&wc->batch_total,
                          &wc->batch_total,
                          &pc->collectable.amount_with_fee))
    {
      GNUNET_break (0);
      return TALER_MHD_reply_with_error (rc->connection,
                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                                         TALER_EC_EXCHANGE_WITHDRAW_AMOUNT_FEE_OVERFLOW,
                                         NULL);
    }

    TALER_coin_ev_hash (&pc->blinded_planchet,
                        &pc->collectable.denom_pub_hash,
                        &pc->collectable.h_coin_envelope);

    TEH_METRICS_num_verifications[TEH_MT_SIGNATURE_EDDSA]++;
    if (GNUNET_OK !=
        TALER_wallet_withdraw_verify (&pc->collectable.denom_pub_hash,
                                      &pc->collectable.amount_with_fee,
                                      &pc->collectable.h_coin_envelope,
                                      &pc->collectable.reserve_pub,
                                      &pc->collectable.reserve_sig))
    {
      GNUNET_break_op (0);
      return TALER_MHD_reply_with_error (rc->connection,
                                         MHD_HTTP_FORBIDDEN,
                                         TALER_EC_EXCHANGE_WITHDRAW_RESERVE_SIGNATURE_INVALID,
                                         NULL);
    }
  }
  /* everything parsed */
  return prepare_transaction (rc,
                              wc);
}


MHD_RESULT
TEH_handler_batch_withdraw (struct TEH_RequestContext *rc,
                            const struct TALER_ReservePublicKeyP *reserve_pub,
                            const json_t *root)
{
  struct BatchWithdrawContext wc = {
    .reserve_pub = reserve_pub,
    .rc = rc
  };
  const json_t *planchets;
  struct GNUNET_JSON_Specification spec[] = {
    GNUNET_JSON_spec_array_const ("planchets",
                                  &planchets),
    GNUNET_JSON_spec_end ()
  };

  GNUNET_assert (GNUNET_OK ==
                 TALER_amount_set_zero (TEH_currency,
                                        &wc.batch_total));
  {
    enum GNUNET_GenericReturnValue res;

    res = TALER_MHD_parse_json_data (rc->connection,
                                     root,
                                     spec);
    if (GNUNET_OK != res)
      return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
  }
  wc.planchets_length = json_array_size (planchets);
  if (0 == wc.planchets_length)
  {
    GNUNET_break_op (0);
    return TALER_MHD_reply_with_error (rc->connection,
                                       MHD_HTTP_BAD_REQUEST,
                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
                                       "planchets");
  }
  if (wc.planchets_length > TALER_MAX_FRESH_COINS)
  {
    GNUNET_break_op (0);
    return TALER_MHD_reply_with_error (rc->connection,
                                       MHD_HTTP_BAD_REQUEST,
                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
                                       "too many planchets");
  }
  {
    struct PlanchetContext splanchets[wc.planchets_length];
    MHD_RESULT ret;

    memset (splanchets,
            0,
            sizeof (splanchets));
    wc.planchets = splanchets;
    ret = parse_planchets (rc,
                           &wc,
                           planchets);
    /* Clean up */
    for (unsigned int i = 0; i<wc.planchets_length; i++)
    {
      struct PlanchetContext *pc = &wc.planchets[i];

      TALER_blinded_planchet_free (&pc->blinded_planchet);
      TALER_blinded_denom_sig_free (&pc->collectable.sig);
    }
    return ret;
  }
}


/* end of taler-exchange-httpd_batch-withdraw.c */