exchange

exchangedb_lib.h (33366B)

---

 /*
   This file is part of TALER
   Copyright (C) 2014-2020 Taler Systems SA
 
   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 include/exchangedb_lib.h
  * @brief IO operations for the exchange's private keys
  * @author Florian Dold
  * @author Benedikt Mueller
  * @author Christian Grothoff
  */
 #ifndef TALER_EXCHANGEDB_LIB_H
 #define TALER_EXCHANGEDB_LIB_H
 
 #include <taler/taler_signatures.h>
 #include <taler/taler_bank_service.h>
 #include <taler/taler_kyclogic_lib.h>
 #include <taler/taler_util.h>
 
 
 /**
  * Detailed status for persisting an AML program result.
  */
 enum TALER_EXCHANGEDB_PersistProgramResultStatus
 {
   TALER_EXCHANGEDB_PPRS_OK = 0,
   TALER_EXCHANGEDB_PPRS_BAD_OUTCOME = 1,
 };
 
 
 /**
  * Why the aggregator decided against executing a wire transfer it had
  * already computed.  Stored in the @e deferral_reason column of the
  * append-only `aggregation_deferrals` table, which is the exchange's claim
  * to the auditor about money it is holding on to.  Values are part of the
  * replicated database format and must not be renumbered.
  */
 enum TALER_EXCHANGEDB_DeferralReason
 {
 
   /**
    * The exchange gave no reason.  Never written; this is what the auditor
    * books a pending transfer under when it finds no `aggregation_deferrals`
    * row for it at all.
    */
   TALER_EXCHANGEDB_DR_NONE = 0,
 
   /**
    * What was aggregated does not survive the wire fee and the rounding to
    * the smallest unit the wire method supports, so the exchange is waiting
    * for further deposits to the same account to make the transfer worth
    * making.
    */
   TALER_EXCHANGEDB_DR_AMOUNT_TOO_SMALL = 1,
 
   /**
    * A legitimization requirement against the recipient account is open, so
    * the exchange must not pay out yet.  The measure in question is named by
    * the @e legitimization_requirement_serial_id column.
    */
   TALER_EXCHANGEDB_DR_KYC = 2
 };
 
 
 /**
  * Information about a denomination key.
  */
 struct TALER_EXCHANGEDB_DenominationKeyInformation
 {
 
   /**
    * Signature over this struct to affirm the validity of the key.
    */
   struct TALER_MasterSignatureP signature;
 
   /**
    * Start time of the validity period for this key.
    */
   struct GNUNET_TIME_Timestamp start;
 
   /**
    * The exchange will sign fresh coins between @e start and this time.
    * @e expire_withdraw will be somewhat larger than @e start to
    * ensure a sufficiently large anonymity set, while also allowing
    * the Exchange to limit the financial damage in case of a key being
    * compromised.  Thus, exchanges with low volume are expected to have a
    * longer withdraw period (@e expire_withdraw - @e start) than exchanges
    * with high transaction volume.  The period may also differ between
    * types of coins.  A exchange may also have a few denomination keys
    * with the same value with overlapping validity periods, to address
    * issues such as clock skew.
    */
   struct GNUNET_TIME_Timestamp expire_withdraw;
 
   /**
    * Coins signed with the denomination key must be spent or refreshed
    * between @e start and this expiration time.  After this time, the
    * exchange will refuse transactions involving this key as it will
    * "drop" the table with double-spending information (shortly after)
    * this time.  Note that wallets should refresh coins significantly
    * before this time to be on the safe side.  @e expire_deposit must be
    * significantly larger than @e expire_withdraw (by months or even
    * years).
    */
   struct GNUNET_TIME_Timestamp expire_deposit;
 
   /**
    * When do signatures with this denomination key become invalid?
    * After this point, these signatures cannot be used in (legal)
    * disputes anymore, as the Exchange is then allowed to destroy its side
    * of the evidence.  @e expire_legal is expected to be significantly
    * larger than @e expire_deposit (by a year or more).
    */
   struct GNUNET_TIME_Timestamp expire_legal;
 
   /**
    * The value of the coins signed with this denomination key.
    */
   struct TALER_Amount value;
 
   /**
    * Fees for the coin.
    */
   struct TALER_DenomFeeSet fees;
 
   /**
    * Hash code of the denomination public key. (Used to avoid having
    * the variable-size RSA key in this struct.)
    */
   struct TALER_DenominationHashP denom_hash;
 
   /**
    * If denomination was setup for age restriction, non-zero age mask.
    * Note that the mask is not part of the signature.
    */
   struct TALER_AgeMask age_mask;
 };
 
 
 GNUNET_NETWORK_STRUCT_BEGIN
 
 /**
  * Events signalling that a coin deposit status
  * changed.
  */
 struct TALER_EXCHANGEDB_CoinDepositEventP
 {
   /**
    * Of type #TALER_DBEVENT_EXCHANGE_DEPOSIT_STATUS_CHANGED.
    */
   struct GNUNET_DB_EventHeaderP header;
 
   /**
    * Public key of the merchant.
    */
   struct TALER_MerchantPublicKeyP merchant_pub;
 
 };
 
 /**
  * Events signalling a reserve got funding.
  */
 struct TALER_EXCHANGEDB_ReserveEventP
 {
   /**
    * Of type #TALER_DBEVENT_EXCHANGE_RESERVE_INCOMING.
    */
   struct GNUNET_DB_EventHeaderP header;
 
   /**
    * Public key of the reserve the event is about.
    */
   struct TALER_ReservePublicKeyP reserve_pub;
 };
 
 
 /**
  * Signature of events signalling a purse changed its status.
  */
 struct TALER_EXCHANGEDB_PurseEventP
 {
   /**
    * Of type #TALER_DBEVENT_EXCHANGE_PURSE_MERGED or
    * #TALER_DBEVENT_EXCHANGE_PURSE_DEPOSITED.
    */
   struct GNUNET_DB_EventHeaderP header;
 
   /**
    * Public key of the purse the event is about.
    */
   struct TALER_PurseContractPublicKeyP purse_pub;
 };
 
 
 /**
  * Signature of events signalling a KYC process was completed.
  */
 struct TALER_EXCHANGEDB_KycCompletedEventP
 {
   /**
    * Of type #TALER_DBEVENT_EXCHANGE_KYC_COMPLETED.
    */
   struct GNUNET_DB_EventHeaderP header;
 
   /**
    * Hash of payto://-URI for which the KYC state changed.
    */
   struct TALER_NormalizedPaytoHashP h_payto;
 };
 
 
 GNUNET_NETWORK_STRUCT_END
 
 /**
  * Meta data about an exchange online signing key.
  */
 struct TALER_EXCHANGEDB_SignkeyMetaData
 {
   /**
    * Start time of the validity period for this key.
    */
   struct GNUNET_TIME_Timestamp start;
 
   /**
    * The exchange will sign messages with this key between @e start and this time.
    */
   struct GNUNET_TIME_Timestamp expire_sign;
 
   /**
    * When do signatures with this sign key become invalid?
    * After this point, these signatures cannot be used in (legal)
    * disputes anymore, as the Exchange is then allowed to destroy its side
    * of the evidence.  @e expire_legal is expected to be significantly
    * larger than @e expire_sign (by a year or more).
    */
   struct GNUNET_TIME_Timestamp expire_legal;
 
 };
 
 
 /**
  * @brief All information about a denomination key (which is used to
  * sign coins into existence).
  */
 struct TALER_EXCHANGEDB_DenominationKey
 {
   /**
    * The private key of the denomination.  Will be NULL if the private
    * key is not available (this is the case after the key has expired
    * for signing coins, but is still valid for depositing coins).
    */
   struct TALER_DenominationPrivateKey denom_priv;
 
   /**
    * Decoded denomination public key (the hash of it is in
    * @e issue, but we sometimes need the full public key as well).
    */
   struct TALER_DenominationPublicKey denom_pub;
 
   /**
    * Signed public information about a denomination key.
    */
   struct TALER_EXCHANGEDB_DenominationKeyInformation issue;
 };
 
 
 /**
  * @brief A summary of a Reserve
  */
 struct TALER_EXCHANGEDB_Reserve
 {
   /**
    * The reserve's public key.  This uniquely identifies the reserve
    */
   struct TALER_ReservePublicKeyP pub;
 
   /**
    * The balance amount existing in the reserve
    */
   struct TALER_Amount balance;
 
   /**
    * The expiration date of this reserve; funds will be wired back
    * at this time.
    */
   struct GNUNET_TIME_Timestamp expiry;
 
   /**
    * The legal expiration date of this reserve; we will forget about
    * it at this time.
    */
   struct GNUNET_TIME_Timestamp gc;
 };
 
 
 /**
  * Public key to which a nonce is locked.
  */
 union TALER_EXCHANGEDB_NonceLockTargetP
 {
   /**
    * Nonce is locked to this coin key.
    */
   struct TALER_CoinSpendPublicKeyP coin;
 
   /**
    * Nonce is locked to this reserve key.
    */
   struct TALER_ReservePublicKeyP reserve;
 };
 
 
 /**
  * @brief Data about a coin for a deposit operation.
  */
 struct TALER_EXCHANGEDB_CoinDepositInformation
 {
   /**
    * Information about the coin that is being deposited.
    */
   struct TALER_CoinPublicInfo coin;
 
   /**
    * ECDSA signature affirming that the customer intends
    * this coin to be deposited at the merchant identified
    * by @e h_wire in relation to the proposal data identified
    * by @e h_contract_terms.
    */
   struct TALER_CoinSpendSignatureP csig;
 
   /**
    * Fraction of the coin's remaining value to be deposited, including
    * depositing fee (if any).  The coin is identified by @e coin_pub.
    */
   struct TALER_Amount amount_with_fee;
 
 };
 
 
 /**
  * @brief Data from a batch deposit operation.
  */
 struct TALER_EXCHANGEDB_BatchDeposit
 {
 
   /**
    * Public key of the merchant.  Enables later identification
    * of the merchant in case of a need to rollback transactions.
    */
   struct TALER_MerchantPublicKeyP merchant_pub;
 
   /**
    * Signature of the merchant over the contract, of purpose
    * #TALER_SIGNATURE_MERCHANT_CONTRACT.
    */
   struct TALER_MerchantSignatureP merchant_sig;
 
   /**
    * Hash over the proposal data between merchant and customer
    * (remains unknown to the Exchange).
    */
   struct TALER_PrivateContractHashP h_contract_terms;
 
   /**
    * Hash over additional inputs by the wallet.
    */
   struct GNUNET_HashCode wallet_data_hash;
 
   /**
    * Unsalted hash over @e receiver_wire_account.
    */
   struct TALER_FullPaytoHashP wire_target_h_payto;
 
   /**
    * Salt used by the merchant to compute "h_wire".
    */
   struct TALER_WireSaltP wire_salt;
 
   /**
    * Time when this request was generated.  Used, for example, to
    * assess when (roughly) the income was achieved for tax purposes.
    * Note that the Exchange will only check that the timestamp is not "too
    * far" into the future (i.e. several days).  The fact that the
    * timestamp falls within the validity period of the coin's
    * denomination key is irrelevant for the validity of the deposit
    * request, as obviously the customer and merchant could conspire to
    * set any timestamp.  Also, the Exchange must accept very old deposit
    * requests, as the merchant might have been unable to transmit the
    * deposit request in a timely fashion (so back-dating is not
    * prevented).
    */
   struct GNUNET_TIME_Timestamp wallet_timestamp;
 
   /**
    * How much time does the merchant have to issue a refund request?
    * Zero if refunds are not allowed.  After this time, the coin
    * cannot be refunded.
    */
   struct GNUNET_TIME_Timestamp refund_deadline;
 
   /**
    * How much time does the merchant have to execute the wire transfer?
    * This time is advisory for aggregating transactions, not a hard
    * constraint (as the merchant can theoretically pick any time,
    * including one in the past).
    */
   struct GNUNET_TIME_Timestamp wire_deadline;
 
   /**
    * Row ID of the policy details; 0 if no policy applies.
    */
   uint64_t policy_details_serial_id;
 
   /**
    * Information about the receiver for executing the transaction.  URI in
    * payto://-format.
    */
   struct TALER_FullPayto receiver_wire_account;
 
   /**
    * Optional extra information to include in the wire transfer
    * subject.
    */
   const char *extra_wire_subject_metadata;
 
   /**
    * Array about the coins that are being deposited.
    */
   const struct TALER_EXCHANGEDB_CoinDepositInformation *cdis;
 
   /**
    * Length of the @e cdis array.
    */
   unsigned int num_cdis;
 
   /**
    * False if @e wallet_data_hash was provided
    */
   bool no_wallet_data_hash;
 
   /**
    * True if further processing is blocked by policy.
    */
   bool policy_blocked;
 
 };
 
 
 /**
  * @brief Data from a deposit operation.  The combination of
  * the coin's public key, the merchant's public key and the
  * transaction ID must be unique.  While a coin can (theoretically) be
  * deposited at the same merchant twice (with partial spending), the
  * merchant must either use a different public key or a different
  * transaction ID for the two transactions.  The same coin must not
  * be used twice at the same merchant for the same transaction
  * (as determined by transaction ID).
  */
 struct TALER_EXCHANGEDB_Deposit
 {
   /**
    * Information about the coin that is being deposited.
    */
   struct TALER_CoinPublicInfo coin;
 
   /**
    * ECDSA signature affirming that the customer intends
    * this coin to be deposited at the merchant identified
    * by @e h_wire in relation to the proposal data identified
    * by @e h_contract_terms.
    */
   struct TALER_CoinSpendSignatureP csig;
 
   /**
    * Public key of the merchant.  Enables later identification
    * of the merchant in case of a need to rollback transactions.
    */
   struct TALER_MerchantPublicKeyP merchant_pub;
 
   /**
    * Hash over the proposal data between merchant and customer
    * (remains unknown to the Exchange).
    */
   struct TALER_PrivateContractHashP h_contract_terms;
 
   /**
    * Salt used by the merchant to compute "h_wire".
    */
   struct TALER_WireSaltP wire_salt;
 
   /**
    * Hash over inputs from the wallet to customize the contract.
    */
   struct GNUNET_HashCode wallet_data_hash;
 
   /**
    * Hash over the policy data for this deposit (remains unknown to the
    * Exchange).  Needed for the verification of the deposit's signature
    */
   struct TALER_ExtensionPolicyHashP h_policy;
 
   /**
    * Time when this request was generated.  Used, for example, to
    * assess when (roughly) the income was achieved for tax purposes.
    * Note that the Exchange will only check that the timestamp is not "too
    * far" into the future (i.e. several days).  The fact that the
    * timestamp falls within the validity period of the coin's
    * denomination key is irrelevant for the validity of the deposit
    * request, as obviously the customer and merchant could conspire to
    * set any timestamp.  Also, the Exchange must accept very old deposit
    * requests, as the merchant might have been unable to transmit the
    * deposit request in a timely fashion (so back-dating is not
    * prevented).
    */
   struct GNUNET_TIME_Timestamp timestamp;
 
   /**
    * How much time does the merchant have to issue a refund request?
    * Zero if refunds are not allowed.  After this time, the coin
    * cannot be refunded.
    */
   struct GNUNET_TIME_Timestamp refund_deadline;
 
   /**
    * How much time does the merchant have to execute the wire transfer?
    * This time is advisory for aggregating transactions, not a hard
    * constraint (as the merchant can theoretically pick any time,
    * including one in the past).
    */
   struct GNUNET_TIME_Timestamp wire_deadline;
 
   /**
    * Fraction of the coin's remaining value to be deposited, including
    * depositing fee (if any).  The coin is identified by @e coin_pub.
    */
   struct TALER_Amount amount_with_fee;
 
   /**
    * Depositing fee.
    */
   struct TALER_Amount deposit_fee;
 
   /**
    * Information about the receiver for executing the transaction.  URI in
    * payto://-format.
    */
   struct TALER_FullPayto receiver_wire_account;
 
   /**
    * True if @e policy_json was provided
    */
   bool has_policy;
 
   /**
    * True if @e wallet_data_hash is not in use.
    */
   bool no_wallet_data_hash;
 
 };
 
 
 /**
  * @brief Specification for coin in a melt operation.
  */
 struct TALER_EXCHANGEDB_Refresh
 {
   /**
    * Information about the coin that is being melted.
    */
   struct TALER_CoinPublicInfo coin;
 
   /**
    * Signature over the melting operation.
    */
   struct TALER_CoinSpendSignatureP coin_sig;
 
   /**
    * Refresh commitment this coin is melted into.
    */
   struct TALER_RefreshCommitmentP rc;
 
   /**
    * How much value is being melted?  This amount includes the fees,
    * so the final amount contributed to the melt is this value minus
    * the fee for melting the coin.  We include the fee 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;
 
   /**
    * Index (smaller #TALER_CNC_KAPPA) which the exchange has chosen to not
    * have revealed during cut and choose.
    */
   uint32_t noreveal_index;
 
 };
 
 
 /**
  * Information about a /purses/$PID/deposit operation.
  */
 struct TALER_EXCHANGEDB_PurseDeposit
 {
 
   /**
    * Exchange hosting the purse, NULL for this exchange.
    */
   char *exchange_base_url;
 
   /**
    * Public key of the purse.
    */
   struct TALER_PurseContractPublicKeyP purse_pub;
 
   /**
    * Contribution of the coin to the purse, including
    * deposit fee.
    */
   struct TALER_Amount amount;
 
   /**
    * Depositing fee.
    */
   struct TALER_Amount deposit_fee;
 
   /**
    * Signature by the coin affirming the deposit.
    */
   struct TALER_CoinSpendSignatureP coin_sig;
 
   /**
    * Public key of the coin.
    */
   struct TALER_CoinSpendPublicKeyP coin_pub;
 
   /**
    * Hash of the age commitment used to sign the coin, if age restriction was
    * applicable to the denomination.  May be all zeroes if no age restriction
    * applies.
    */
   struct TALER_AgeCommitmentHashP h_age_commitment;
 
   /**
    * Set to true if @e h_age_commitment is not available.
    */
   bool no_age_commitment;
 
 };
 
 
 /**
  * Information about a melt operation since vDOLDPLUS of the protocol.
  * This also includes the information for the reveal phase.
  */
 struct TALER_EXCHANGEDB_Refresh_vDOLDPLUS
 {
   /**
    * Information about the coin that is being melted.
    */
   struct TALER_CoinPublicInfo coin;
 
   /**
    * Signature over the melting operation.
    */
   struct TALER_CoinSpendSignatureP coin_sig;
 
   /**
    * Refresh commitment this coin is melted into.
    */
   struct TALER_RefreshCommitmentP rc;
 
   /**
    * True if the client has successfully performed the reveal part
    * of the refresh protocol, after the melt.
    */
   bool is_revealed;
 
   /**
    * @since vDOLDPLUS
    * Mark if we have a v27 Refresh object.
    * That is, the @a refresh_seed refers to the vDOLDPLUS master_refresh_seed
    * from the original request, AND the client has provided transfer public keys,
    * see below, @a transfer_public_keys
    */
   bool is_v27_refresh;
 
   /**
    * Public seed from which the refresh nonces (v27) or transfer secrets (vDOLDPLUS)
    * per coin candidate were derived from.
    */
   struct TALER_PublicRefreshMasterSeedP refresh_seed;
 
   /**
    * How much value is being melted?  This amount includes the fees,
    * so the final amount contributed to the melt is this value minus
    * the fee for melting the coin.  We include the fee 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;
 
   /**
    * Number of coins to be refreshed into
    */
   size_t num_coins;
 
   /**
    * The running hash over all  kappa * @a num_coins blinded coin envelopes, provided by
    * the client.
    */
   struct TALER_HashBlindedPlanchetsP planchets_h;
 
   /**
    * The running hash over all chosen (noreveal_index) @a num_coins blinded coin envelopes.
    */
   struct TALER_HashBlindedPlanchetsP selected_h;
 
   /**
    * Array of @a num_coins denomination signatures of the blinded coins.
    */
   struct TALER_BlindedDenominationSignature *denom_sigs;
 
   /**
    * If @a is_v27_refresh is false, the client performed a vDOLDPLUS refresh,
    * and has provided @a num_coins * kappa transfer public keys.
    * This is the chosen (at index @a noreveal_index) array of @a num_coins transfer public keys.
    */
   struct TALER_TransferPublicKeyP *transfer_pubs;
 
   /**
    * Array of @a num_coins serial id's of the denominations.
    * If @e coin.no_age_commitment is false, the denominations
    * MUST support age restriction.
    */
   uint64_t *denom_serials;
 
   /**
    * Index (smaller #TALER_CNC_KAPPA) which the exchange chose to not
    * to be revealed during cut and choose.
    */
   uint32_t noreveal_index;
 
   /**
    * True, if the client has successfully performed the reveal step
    */
   bool revealed;
 
   /**
    * If true, no @e blinding_seed is set and @e num_cs_r_values is 0.
    */
   bool no_blinding_seed;
 
   /**
    * If @e no_blinding_seed is false, the blinding seed for the nonces needed for
    * blind CS signatures.
    */
   struct TALER_BlindingMasterSeedP blinding_seed;
 
   /**
    * Number of elements in @e cs_r_values.
    */
   size_t num_cs_r_values;
 
   /**
    * Array @e num_cs_r_values of public R-values for CS that were generated from the
    * @e blinding_seed, a coin's index and the denomination's private key during the
    * the /melt request, to ensure idempotency in case of expiration of a denomination.
    * NULL if @e num_cs_r_values is 0.
    */
   struct GNUNET_CRYPTO_CSPublicRPairP *cs_r_values;
 
   /**
    * If @e num_cs_r_values is not 0, the bitvector of choices for the pairs
    * in @e cs_r_values that was made by the exchange.  The vector is in NBO
    * and the lowest bit represents the choice for the pair at index 0 into @e cs_r_values;
    */
   uint64_t cs_r_choices;
 
   /**
    * [out]-Array of @a num_coins hashes of the public keys of the denominations
    * identified by @e denom_serials.  This field is set when calling
    * get_refresh
    */
   struct TALER_DenominationHashP *denom_pub_hashes;
 };
 
 
 /**
  * Generic KYC status for some operation.
  */
 struct TALER_EXCHANGEDB_KycStatus
 {
 
   /**
    * Account public key that is currently associated
    * with the account. Only set if @e have_account_pub
    * is true.
    */
   union TALER_AccountPublicKeyP account_pub;
 
   /**
    * Number that identifies the KYC requirement the operation
    * was about.
    */
   uint64_t requirement_row;
 
   /**
    * True if @e account_pub is set.
    */
   bool have_account_pub;
 
   /**
    * True if the KYC status is "satisfied".
    */
   bool ok;
 
 };
 
 
 /**
  * Function called with details about incoming wire transfers.
  *
  * @param cls closure
  * @param rowid unique serial ID for the refresh session in our DB
  * @param reserve_pub public key of the reserve (also the wire subject)
  * @param credit amount that was received
  * @param sender_account_details information about the sender's bank account, in payto://-format
  * @param wire_reference unique identifier for the wire transfer
  * @param execution_date when did we receive the funds
  * @return #GNUNET_OK to continue to iterate, #GNUNET_SYSERR to stop
  */
 #ifndef TALER_EXCHANGEDB_RESERVE_IN_RESULT_CLOSURE
 #define TALER_EXCHANGEDB_RESERVE_IN_RESULT_CLOSURE void
 #endif
 typedef enum GNUNET_GenericReturnValue
 (*TALER_EXCHANGEDB_ReserveInCallback)(
   TALER_EXCHANGEDB_RESERVE_IN_RESULT_CLOSURE *cls,
   uint64_t rowid,
   const struct TALER_ReservePublicKeyP *reserve_pub,
   const struct TALER_Amount *credit,
   const struct TALER_FullPayto sender_account_details,
   uint64_t wire_reference,
   struct GNUNET_TIME_Timestamp execution_date);
 
 
 /**
  * Function called with the results of the lookup of the
  * wire transfer data of the exchange.
  *
  * @param cls closure
  * @param rowid identifier of the respective row in the database
  * @param date timestamp of the wire transfer (roughly)
  * @param wtid wire transfer subject
  * @param payto_uri details of the receiver, URI in payto://-format
  * @param amount amount that was wired
  * @return #GNUNET_OK to continue, #GNUNET_SYSERR to stop iteration
  */
 #ifndef TALER_EXCHANGEDB_WIRE_TRANSFER_OUT_RESULT_CLOSURE
 #define TALER_EXCHANGEDB_WIRE_TRANSFER_OUT_RESULT_CLOSURE void
 #endif
 typedef enum GNUNET_GenericReturnValue
 (*TALER_EXCHANGEDB_WireTransferOutCallback)(
   TALER_EXCHANGEDB_WIRE_TRANSFER_OUT_RESULT_CLOSURE *cls,
   uint64_t rowid,
   struct GNUNET_TIME_Timestamp date,
   const struct TALER_WireTransferIdentifierRawP *wtid,
   const struct TALER_FullPayto payto_uri,
   const struct TALER_Amount *amount);
 
 
 /**
  * Function called with details about expired reserves.
  *
  * @param cls closure
  * @param reserve_pub public key of the reserve
  * @param left amount left in the reserve
  * @param account_details information about the reserve's bank account, in payto://-format
  * @param expiration_date when did the reserve expire
  * @param close_request_row row that caused the reserve
  *        to be closed, 0 if it expired without request
  * @return #GNUNET_OK on success,
  *         #GNUNET_NO to retry
  *         #GNUNET_SYSERR on hard failures (exit)
  */
 #ifndef TALER_EXCHANGEDB_RESERVE_EXPIRED_RESULT_CLOSURE
 #define TALER_EXCHANGEDB_RESERVE_EXPIRED_RESULT_CLOSURE void
 #endif
 typedef enum GNUNET_GenericReturnValue
 (*TALER_EXCHANGEDB_ReserveExpiredCallback)(
   TALER_EXCHANGEDB_RESERVE_EXPIRED_RESULT_CLOSURE *cls,
   const struct TALER_ReservePublicKeyP *reserve_pub,
   const struct TALER_Amount *left,
   const struct TALER_FullPayto account_details,
   struct GNUNET_TIME_Timestamp expiration_date,
   uint64_t close_request_row);
 
 
 /**
  * Callback that is given AML-relevant transfer data.
  *
  * @param cls closure
  * @param row_id current row in AML status table
  * @param payto_uri account involved with the wire transfer
  * @param execution_time when was the transfer made
  * @param amount wire amount of the transfer
  */
 #ifndef TALER_EXCHANGEDB_AML_TRANSFER_RESULT_CLOSURE
 #define TALER_EXCHANGEDB_AML_TRANSFER_RESULT_CLOSURE void
 #endif
 typedef void
 (*TALER_EXCHANGEDB_AmlTransferCallback)(
   TALER_EXCHANGEDB_AML_TRANSFER_RESULT_CLOSURE *cls,
   uint64_t row_id,
   const char *payto_uri,
   struct GNUNET_TIME_Absolute execution_time,
   const struct TALER_Amount *amount);
 
 
 /**
  * Initialize the database connection.
  *
  * @param cfg configuration to use
  * @return NULL on failure
  */
 struct TALER_EXCHANGEDB_PostgresContext *
 TALER_EXCHANGEDB_connect (
   const struct GNUNET_CONFIGURATION_Handle *cfg);
 
 
 /**
  * Initialize the database connection for administration.
  * Disables the check that the database schema is current.
  *
  * @param cfg configuration to use
  * @return NULL on failure
  */
 struct TALER_EXCHANGEDB_PostgresContext *
 TALER_EXCHANGEDB_connect_admin (
   const struct GNUNET_CONFIGURATION_Handle *cfg);
 
 
 /**
  * Shutdown the database connection.
  *
  * @param[in] pg connection to drop
  */
 void
 TALER_EXCHANGEDB_disconnect (struct TALER_EXCHANGEDB_PostgresContext *pg);
 
 
 /**
  * Meta data about a denomination public key.
  * If this is changed, you must also adjust
  * taler-exchange-httpd-post-management-keys.c::denomination_meta_cmp().
  */
 struct TALER_EXCHANGEDB_DenominationKeyMetaData
 {
   /**
    * Serial of the denomination key as in the DB.
    * Can be used calls to stored procedures in order to spare
    * additional lookups.
    */
   uint64_t serial;
 
   /**
    * Start time of the validity period for this key.
    */
   struct GNUNET_TIME_Timestamp start;
 
   /**
    * The exchange will sign fresh coins between @e start and this time.
    * @e expire_withdraw will be somewhat larger than @e start to
    * ensure a sufficiently large anonymity set, while also allowing
    * the Exchange to limit the financial damage in case of a key being
    * compromised.  Thus, exchanges with low volume are expected to have a
    * longer withdraw period (@e expire_withdraw - @e start) than exchanges
    * with high transaction volume.  The period may also differ between
    * types of coins.  A exchange may also have a few denomination keys
    * with the same value with overlapping validity periods, to address
    * issues such as clock skew.
    */
   struct GNUNET_TIME_Timestamp expire_withdraw;
 
   /**
    * Coins signed with the denomination key must be spent or refreshed
    * between @e start and this expiration time.  After this time, the
    * exchange will refuse transactions involving this key as it will
    * "drop" the table with double-spending information (shortly after)
    * this time.  Note that wallets should refresh coins significantly
    * before this time to be on the safe side.  @e expire_deposit must be
    * significantly larger than @e expire_withdraw (by months or even
    * years).
    */
   struct GNUNET_TIME_Timestamp expire_deposit;
 
   /**
    * When do signatures with this denomination key become invalid?
    * After this point, these signatures cannot be used in (legal)
    * disputes anymore, as the Exchange is then allowed to destroy its side
    * of the evidence.  @e expire_legal is expected to be significantly
    * larger than @e expire_deposit (by a year or more).
    */
   struct GNUNET_TIME_Timestamp expire_legal;
 
   /**
    * The value of the coins signed with this denomination key.
    */
   struct TALER_Amount value;
 
   /**
    * The fees the exchange charges for operations with
    * coins of this denomination.
    */
   struct TALER_DenomFeeSet fees;
 
   /**
    * Age restriction for the denomination. (can be zero). If not zero, the bits
    * set in the mask mark the edges at the beginning of a next age group.  F.e.
    * for the age groups
    *     0-7, 8-9, 10-11, 12-14, 14-15, 16-17, 18-21, 21-*
    * the following bits are set:
    *
    *   31     24        16        8         0
    *   |      |         |         |         |
    *   oooooooo  oo1oo1o1  o1o1o1o1  ooooooo1
    *
    * A value of 0 means that the denomination does not support the extension for
    * age-restriction.
    */
   struct TALER_AgeMask age_mask;
 };
 
 
 /**
  * Information about an account from the configuration.
  */
 struct TALER_EXCHANGEDB_AccountInfo
 {
   /**
    * Authentication data. Only parsed if
    * #TALER_EXCHANGEDB_ALO_AUTHDATA was set.
    */
   const struct TALER_BANK_AuthenticationData *auth;
 
   /**
    * Section in the configuration file that specifies the
    * account. Must start with "exchange-account-".
    */
   const char *section_name;
 
   /**
    * Name of the wire method used by this account.
    */
   const char *method;
 
   /**
    * Full payto://-URI of the account. Do not free(), aliased
    * with the underlying `struct WireAccount`.
    */
   struct TALER_FullPayto payto_uri;
 
   /**
    * true if this account is enabled to be debited
    * by the taler-exchange-aggregator.
    */
   bool debit_enabled;
 
   /**
    * true if this account is enabled to be credited by wallets
    * and needs to be watched by the taler-exchange-wirewatch.
    * Also, the account will only be included in /wire if credit
    * is enabled.
    */
   bool credit_enabled;
 };
 
 
 /**
  * Function called with information about a wire account.
  *
  * @param cls closure
  * @param ai account information
  */
 #ifndef TALER_EXCHANGEDB_ACCOUNT_RESULT_CLOSURE
 #define TALER_EXCHANGEDB_ACCOUNT_RESULT_CLOSURE void
 #endif
 typedef void
 (*TALER_EXCHANGEDB_AccountCallback)(
   TALER_EXCHANGEDB_ACCOUNT_RESULT_CLOSURE *cls,
   const struct TALER_EXCHANGEDB_AccountInfo *ai);
 
 
 /**
  * Return information about all accounts that
  * were loaded by #TALER_EXCHANGEDB_load_accounts().
  *
  * @param cb callback to invoke
  * @param cb_cls closure for @a cb
  */
 void
 TALER_EXCHANGEDB_find_accounts (TALER_EXCHANGEDB_AccountCallback cb,
                                 TALER_EXCHANGEDB_ACCOUNT_RESULT_CLOSURE *cb_cls)
 ;
 
 
 /**
  * Find the wire plugin for the given payto:// URL.
  * Only useful after the accounts have been loaded
  * using #TALER_EXCHANGEDB_load_accounts().
  *
  * @param method wire method we need an account for
  * @return NULL on error
  */
 const struct TALER_EXCHANGEDB_AccountInfo *
 TALER_EXCHANGEDB_find_account_by_method (const char *method);
 
 
 /**
  * Find the wire plugin for the given payto:// URL
  * Only useful after the accounts have been loaded
  * using #TALER_EXCHANGEDB_load_accounts().
  *
  * @param url wire address we need an account for
  * @return NULL on error
  */
 const struct TALER_EXCHANGEDB_AccountInfo *
 TALER_EXCHANGEDB_find_account_by_payto_uri (
   const struct TALER_FullPayto url);
 
 
 /**
  * Options for #TALER_EXCHANGEDB_load_accounts()
  */
 enum TALER_EXCHANGEDB_AccountLoaderOptions
 {
   TALER_EXCHANGEDB_ALO_NONE = 0,
 
   /**
    * Load accounts enabled for DEBITs.
    */
   TALER_EXCHANGEDB_ALO_DEBIT = 1,
 
   /**
    * Load accounts enabled for CREDITs.
    */
   TALER_EXCHANGEDB_ALO_CREDIT = 2,
 
   /**
    * Load authentication data from the
    * "taler-accountcredentials-" section
    * to access the account at the bank.
    */
   TALER_EXCHANGEDB_ALO_AUTHDATA = 4
 };
 
 
 /**
  * Load account information op the exchange from @a cfg.
  *
  * @param cfg configuration to load from
  * @param options loader options
  * @return #GNUNET_OK on success, #GNUNET_NO if no accounts are configured
  */
 enum GNUNET_GenericReturnValue
 TALER_EXCHANGEDB_load_accounts (
   const struct GNUNET_CONFIGURATION_Handle *cfg,
   enum TALER_EXCHANGEDB_AccountLoaderOptions options);
 
 
 /**
  * Free resources allocated by
  * #TALER_EXCHANGEDB_load_accounts().
  */
 void
 TALER_EXCHANGEDB_unload_accounts (void);
 
 
 #endif