/*
This file is part of TALER
Copyright (C) 2014-2017 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
*/
/**
* @file include/taler_exchange_service.h
* @brief C interface of libtalerexchange, a C library to use exchange's HTTP API
* @author Sree Harsha Totakura
* @author Christian Grothoff
*/
#ifndef _TALER_EXCHANGE_SERVICE_H
#define _TALER_EXCHANGE_SERVICE_H
#include
#include "taler_util.h"
#include "taler_error_codes.h"
#include
/* ********************* /keys *********************** */
/**
* List of possible options to be passed to
* #TALER_EXCHANGE_connect().
*/
enum TALER_EXCHANGE_Option
{
/**
* Terminator (end of option list).
*/
TALER_EXCHANGE_OPTION_END = 0
};
/**
* @brief Exchange's signature key
*/
struct TALER_EXCHANGE_SigningPublicKey
{
/**
* The signing public key
*/
struct TALER_ExchangePublicKeyP key;
/**
* Validity start time
*/
struct GNUNET_TIME_Absolute valid_from;
/**
* Validity expiration time
*/
struct GNUNET_TIME_Absolute valid_until;
};
/**
* @brief Public information about a exchange's denomination key
*/
struct TALER_EXCHANGE_DenomPublicKey
{
/**
* The public key
*/
struct TALER_DenominationPublicKey key;
/**
* The hash of the public key.
*/
struct GNUNET_HashCode h_key;
/**
* Timestamp indicating when the denomination key becomes valid
*/
struct GNUNET_TIME_Absolute valid_from;
/**
* Timestamp indicating when the denomination key can’t be used anymore to
* withdraw new coins.
*/
struct GNUNET_TIME_Absolute withdraw_valid_until;
/**
* Timestamp indicating when coins of this denomination become invalid.
*/
struct GNUNET_TIME_Absolute 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_Absolute expire_legal;
/**
* The value of this denomination
*/
struct TALER_Amount value;
/**
* The applicable fee for withdrawing a coin of this denomination
*/
struct TALER_Amount fee_withdraw;
/**
* The applicable fee to spend a coin of this denomination
*/
struct TALER_Amount fee_deposit;
/**
* The applicable fee to melt/refresh a coin of this denomination
*/
struct TALER_Amount fee_refresh;
/**
* The applicable fee to refund a coin of this denomination
*/
struct TALER_Amount fee_refund;
};
/**
* @brief Information we get from the exchange about auditors.
*/
struct TALER_EXCHANGE_AuditorInformation
{
/**
* Public key of the auditing institution. Wallets and merchants
* are expected to be configured with a set of public keys of
* auditors that they deem acceptable. These public keys are
* the roots of the Taler PKI.
*/
struct TALER_AuditorPublicKeyP auditor_pub;
/**
* URL of the auditing institution. Signed by the auditor's public
* key, this URL is a place where applications can direct users for
* additional information about the auditor. In the future, there
* should also be an auditor API for automated submission about
* claims of misbehaving exchange providers.
*/
char *auditor_url;
/**
* Number of denomination keys audited by this auditor.
*/
unsigned int num_denom_keys;
/**
* Array of length @a num_denom_keys with the denomination
* keys audited by this auditor. Note that the array
* elements point to the same locations as the entries
* in the key's main `denom_keys` array.
*/
const struct TALER_EXCHANGE_DenomPublicKey **denom_keys;
};
/**
* @brief Information about keys from the exchange.
*/
struct TALER_EXCHANGE_Keys
{
/**
* Long-term offline signing key of the exchange.
*/
struct TALER_MasterPublicKeyP master_pub;
/**
* Array of the exchange's online signing keys.
*/
struct TALER_EXCHANGE_SigningPublicKey *sign_keys;
/**
* Array of the exchange's denomination keys.
*/
struct TALER_EXCHANGE_DenomPublicKey *denom_keys;
/**
* Array of the keys of the auditors of the exchange.
*/
struct TALER_EXCHANGE_AuditorInformation *auditors;
/**
* Supported Taler protocol version by the exchange.
* String in the format current:revision:age using the
* semantics of GNU libtool. See
* https://www.gnu.org/software/libtool/manual/html_node/Versioning.html#Versioning
*/
char *version;
/**
* Timestamp indicating the /keys generation.
*/
struct GNUNET_TIME_Absolute list_issue_date;
/**
* Timestamp indicating the creation time of the last
* denomination key in /keys.
* Used to fetch /keys incrementally.
*/
struct GNUNET_TIME_Absolute last_denom_issue_date;
/**
* Length of the @e sign_keys array (number of valid entries).
*/
unsigned int num_sign_keys;
/**
* Length of the @e denom_keys array.
*/
unsigned int num_denom_keys;
/**
* Length of the @e auditors array.
*/
unsigned int num_auditors;
/**
* Actual length of the @e auditors array (size of allocation).
*/
unsigned int auditors_size;
/**
* Actual length of the @e denom_keys array (size of allocation).
*/
unsigned int denom_keys_size;
};
/**
* How compatible are the protocol version of the exchange and this
* client? The bits (1,2,4) can be used to test if the exchange's
* version is incompatible, older or newer respectively.
*/
enum TALER_EXCHANGE_VersionCompatibility
{
/**
* The exchange runs exactly the same protocol version.
*/
TALER_EXCHANGE_VC_MATCH = 0,
/**
* The exchange is too old or too new to be compatible with this
* implementation (bit)
*/
TALER_EXCHANGE_VC_INCOMPATIBLE = 1,
/**
* The exchange is older than this implementation (bit)
*/
TALER_EXCHANGE_VC_OLDER = 2,
/**
* The exchange is too old to be compatible with
* this implementation.
*/
TALER_EXCHANGE_VC_INCOMPATIBLE_OUTDATED
= TALER_EXCHANGE_VC_INCOMPATIBLE
| TALER_EXCHANGE_VC_OLDER,
/**
* The exchange is more recent than this implementation (bit).
*/
TALER_EXCHANGE_VC_NEWER = 4,
/**
* The exchange is too recent for this implementation.
*/
TALER_EXCHANGE_VC_INCOMPATIBLE_NEWER
= TALER_EXCHANGE_VC_INCOMPATIBLE
| TALER_EXCHANGE_VC_NEWER,
/**
* We could not even parse the version data.
*/
TALER_EXCHANGE_VC_PROTOCOL_ERROR = 8
};
/**
* Function called with information about who is auditing
* a particular exchange and what key the exchange is using.
*
* @param cls closure
* @param keys information about the various keys used
* by the exchange, NULL if /keys failed
* @param compat protocol compatibility information
*/
typedef void
(*TALER_EXCHANGE_CertificationCallback) (void *cls,
const struct TALER_EXCHANGE_Keys *keys,
enum TALER_EXCHANGE_VersionCompatibility compat);
/**
* @brief Handle to the exchange. This is where we interact with
* a particular exchange and keep the per-exchange information.
*/
struct TALER_EXCHANGE_Handle;
/**
* Initialise a connection to the exchange. Will connect to the
* exchange and obtain information about the exchange's master public
* key and the exchange's auditor. The respective information will
* be passed to the @a cert_cb once available, and all future
* interactions with the exchange will be checked to be signed
* (where appropriate) by the respective master key.
*
* @param ctx the context
* @param url HTTP base URL for the exchange
* @param cert_cb function to call with the exchange's certification information,
* possibly called repeatedly if the information changes
* @param cert_cb_cls closure for @a cert_cb
* @param ... list of additional arguments, terminated by #TALER_EXCHANGE_OPTION_END.
* @return the exchange handle; NULL upon error
*/
struct TALER_EXCHANGE_Handle *
TALER_EXCHANGE_connect (struct GNUNET_CURL_Context *ctx,
const char *url,
TALER_EXCHANGE_CertificationCallback cert_cb,
void *cert_cb_cls,
...);
/**
* Disconnect from the exchange.
*
* @param exchange the exchange handle
*/
void
TALER_EXCHANGE_disconnect (struct TALER_EXCHANGE_Handle *exchange);
/**
* Obtain the keys from the exchange.
*
* @param exchange the exchange handle
* @return the exchange's key set
*/
const struct TALER_EXCHANGE_Keys *
TALER_EXCHANGE_get_keys (struct TALER_EXCHANGE_Handle *exchange);
/**
* Check if our current response for /keys is valid, and if
* not, trigger /keys download.
*
* @param exchange exchange to check keys for
* @param force_download #GNUNET_YES to force download even if /keys is still valid
* @return until when the response is current, 0 if we are re-downloading
*/
struct GNUNET_TIME_Absolute
TALER_EXCHANGE_check_keys_current (struct TALER_EXCHANGE_Handle *exchange,
int force_download);
/**
* Obtain the keys from the exchange in the raw JSON format.
*
* @param exchange the exchange handle
* @return the exchange's keys in raw JSON
*/
json_t *
TALER_EXCHANGE_get_keys_raw (struct TALER_EXCHANGE_Handle *exchange);
/**
* Test if the given @a pub is a the current signing key from the exchange
* according to @a keys.
*
* @param keys the exchange's key set
* @param pub claimed current online signing key for the exchange
* @return #GNUNET_OK if @a pub is (according to /keys) a current signing key
*/
int
TALER_EXCHANGE_test_signing_key (const struct TALER_EXCHANGE_Keys *keys,
const struct TALER_ExchangePublicKeyP *pub);
/**
* Obtain the denomination key details from the exchange.
*
* @param keys the exchange's key set
* @param pk public key of the denomination to lookup
* @return details about the given denomination key, NULL if the key is not
* found
*/
const struct TALER_EXCHANGE_DenomPublicKey *
TALER_EXCHANGE_get_denomination_key (const struct TALER_EXCHANGE_Keys *keys,
const struct TALER_DenominationPublicKey *pk);
/**
* Obtain the denomination key details from the exchange.
*
* @param keys the exchange's key set
* @param hc hash of the public key of the denomination to lookup
* @return details about the given denomination key
*/
const struct TALER_EXCHANGE_DenomPublicKey *
TALER_EXCHANGE_get_denomination_key_by_hash (const struct TALER_EXCHANGE_Keys *keys,
const struct GNUNET_HashCode *hc);
/* ********************* /wire *********************** */
/**
* Sorted list of fees to be paid for aggregate wire transfers.
*/
struct TALER_EXCHANGE_WireAggregateFees
{
/**
* This is a linked list.
*/
struct TALER_EXCHANGE_WireAggregateFees *next;
/**
* Fee to be paid whenever the exchange wires funds to the merchant.
*/
struct TALER_Amount wire_fee;
/**
* Fee to be paid when the exchange closes a reserve and wires funds
* back to a customer.
*/
struct TALER_Amount closing_fee;
/**
* Time when this fee goes into effect (inclusive)
*/
struct GNUNET_TIME_Absolute start_date;
/**
* Time when this fee stops being in effect (exclusive).
*/
struct GNUNET_TIME_Absolute end_date;
/**
* Signature affirming the above fee structure.
*/
struct TALER_MasterSignatureP master_sig;
};
/**
* Function called with information about the wire fees
* for each wire method.
*
* @param cls closure
* @param wire_method name of the wire method (i.e. "sepa")
* @param fees fee structure for this method
*/
typedef void
(*TALER_EXCHANGE_WireFeeCallback)(void *cls,
const char *wire_method,
const struct TALER_EXCHANGE_WireAggregateFees *fees);
/**
* Obtain information about wire fees encoded in @a obj
* by wire method.
*
* @param master_pub public key to use to verify signatures, NULL to not verify
* @param obj wire information as encoded in the #TALER_EXCHANGE_WireResultCallback
* @param cb callback to invoke for the fees
* @param cb_cls closure for @a cb
* @return #GNUNET_OK in success, #GNUNET_SYSERR if @a obj is ill-formed
*/
int
TALER_EXCHANGE_wire_get_fees (const struct TALER_MasterPublicKeyP *master_pub,
const json_t *obj,
TALER_EXCHANGE_WireFeeCallback cb,
void *cb_cls);
/**
* @brief A Wire format inquiry handle
*/
struct TALER_EXCHANGE_WireHandle;
/**
* Callbacks of this type are used to serve the result of submitting a
* wire format inquiry request to a exchange.
*
* If the request fails to generate a valid response from the
* exchange, @a http_status will also be zero.
*
* @param cls closure
* @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful request;
* 0 if the exchange's reply is bogus (fails to follow the protocol)
* @param ec taler-specific error code, #TALER_EC_NONE on success
* @param obj the received JSON reply, if successful this should be the wire
* format details as provided by /wire, or NULL if the
* reply was not in JSON format.
*/
typedef void
(*TALER_EXCHANGE_WireResultCallback) (void *cls,
unsigned int http_status,
enum TALER_ErrorCode ec,
const json_t *obj);
/**
* Obtain information about a exchange's wire instructions. A
* exchange may provide wire instructions for creating a reserve. The
* wire instructions also indicate which wire formats merchants may
* use with the exchange. This API is typically used by a wallet for
* wiring funds, and possibly by a merchant to determine supported
* wire formats.
*
* Note that while we return the (main) response verbatim to the
* caller for further processing, we do already verify that the
* response is well-formed (i.e. that signatures included in the
* response are all valid). If the exchange's reply is not
* well-formed, we return an HTTP status code of zero to @a cb.
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param wire_cb the callback to call when a reply for this request is available
* @param wire_cb_cls closure for the above callback
* @return a handle for this request
*/
struct TALER_EXCHANGE_WireHandle *
TALER_EXCHANGE_wire (struct TALER_EXCHANGE_Handle *exchange,
TALER_EXCHANGE_WireResultCallback wire_cb,
void *wire_cb_cls);
/**
* Cancel a wire information request. This function cannot be used
* on a request handle if a response is already served for it.
*
* @param wh the wire information request handle
*/
void
TALER_EXCHANGE_wire_cancel (struct TALER_EXCHANGE_WireHandle *wh);
/* ********************* /deposit *********************** */
/**
* @brief A Deposit Handle
*/
struct TALER_EXCHANGE_DepositHandle;
/**
* Callbacks of this type are used to serve the result of submitting a
* deposit permission request to a exchange.
*
* @param cls closure
* @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful deposit;
* 0 if the exchange's reply is bogus (fails to follow the protocol)
* @param sign_key exchange key used to sign @a obj, or NULL
* @param obj the received JSON reply, should be kept as proof (and, in case of errors,
* be forwarded to the customer)
*/
typedef void
(*TALER_EXCHANGE_DepositResultCallback) (void *cls,
unsigned int http_status,
enum TALER_ErrorCode ec,
const struct TALER_ExchangePublicKeyP *sign_key,
const json_t *obj);
/**
* Submit a deposit permission to the exchange and get the exchange's
* response. This API is typically used by a merchant. Note that
* while we return the response verbatim to the caller for further
* processing, we do already verify that the response is well-formed
* (i.e. that signatures included in the response are all valid). If
* the exchange's reply is not well-formed, we return an HTTP status code
* of zero to @a cb.
*
* We also verify that the @a coin_sig is valid for this deposit
* request, and that the @a ub_sig is a valid signature for @a
* coin_pub. Also, the @a exchange must be ready to operate (i.e. have
* finished processing the /keys reply). If either check fails, we do
* NOT initiate the transaction with the exchange and instead return NULL.
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param amount the amount to be deposited
* @param wire_deadline execution date, until which the merchant would like the exchange to settle the balance (advisory, the exchange cannot be
* forced to settle in the past or upon very short notice, but of course a well-behaved exchange will limit aggregation based on the advice received)
* @param wire_details the merchant’s account details, in a format supported by the exchange
* @param h_contract_terms hash of the contact of the merchant with the customer (further details are never disclosed to the exchange)
* @param coin_pub coin’s public key
* @param denom_pub denomination key with which the coin is signed
* @param denom_sig exchange’s unblinded signature of the coin
* @param timestamp timestamp when the contract was finalized, must match approximately the current time of the exchange
* @param merchant_pub the public key of the merchant (used to identify the merchant for refund requests)
* @param refund_deadline date until which the merchant can issue a refund to the customer via the exchange (can be zero if refunds are not allowed); must not be after the @a wire_deadline
* @param coin_sig the signature made with purpose #TALER_SIGNATURE_WALLET_COIN_DEPOSIT made by the customer with the coin’s private key.
* @param cb the callback to call when a reply for this request is available
* @param cb_cls closure for the above callback
* @return a handle for this request; NULL if the inputs are invalid (i.e.
* signatures fail to verify). In this case, the callback is not called.
*/
struct TALER_EXCHANGE_DepositHandle *
TALER_EXCHANGE_deposit (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_Amount *amount,
struct GNUNET_TIME_Absolute wire_deadline,
json_t *wire_details,
const struct GNUNET_HashCode *h_contract_terms,
const struct TALER_CoinSpendPublicKeyP *coin_pub,
const struct TALER_DenominationSignature *denom_sig,
const struct TALER_DenominationPublicKey *denom_pub,
struct GNUNET_TIME_Absolute timestamp,
const struct TALER_MerchantPublicKeyP *merchant_pub,
struct GNUNET_TIME_Absolute refund_deadline,
const struct TALER_CoinSpendSignatureP *coin_sig,
TALER_EXCHANGE_DepositResultCallback cb,
void *cb_cls);
/**
* Cancel a deposit permission request. This function cannot be used
* on a request handle if a response is already served for it.
*
* @param deposit the deposit permission request handle
*/
void
TALER_EXCHANGE_deposit_cancel (struct TALER_EXCHANGE_DepositHandle *deposit);
/* ********************* /refund *********************** */
/**
* @brief A Refund Handle
*/
struct TALER_EXCHANGE_RefundHandle;
/**
* Callbacks of this type are used to serve the result of submitting a
* refund request to an exchange.
*
* @param cls closure
* @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful deposit;
* 0 if the exchange's reply is bogus (fails to follow the protocol)
* @param ec taler-specific error code, #TALER_EC_NONE on success
* @param sign_key exchange key used to sign @a obj, or NULL
* @param obj the received JSON reply, should be kept as proof (and, in particular,
* be forwarded to the customer)
*/
typedef void
(*TALER_EXCHANGE_RefundResultCallback) (void *cls,
unsigned int http_status,
enum TALER_ErrorCode ec,
const struct TALER_ExchangePublicKeyP *sign_key,
const json_t *obj);
/**
* Submit a refund request to the exchange and get the exchange's
* response. This API is used by a merchant. Note that
* while we return the response verbatim to the caller for further
* processing, we do already verify that the response is well-formed
* (i.e. that signatures included in the response are all valid). If
* the exchange's reply is not well-formed, we return an HTTP status code
* of zero to @a cb.
*
* The @a exchange must be ready to operate (i.e. have
* finished processing the /keys reply). If this check fails, we do
* NOT initiate the transaction with the exchange and instead return NULL.
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param amount the amount to be refunded; must be larger than the refund fee
* (as that fee is still being subtracted), and smaller than the amount
* (with deposit fee) of the original deposit contribution of this coin
* @param refund_fee fee applicable to this coin for the refund
* @param h_contract_terms hash of the contact of the merchant with the customer that is being refunded
* @param coin_pub coin’s public key of the coin from the original deposit operation
* @param rtransaction_id transaction id for the transaction between merchant and customer (of refunding operation);
* this is needed as we may first do a partial refund and later a full refund. If both
* refunds are also over the same amount, we need the @a rtransaction_id to make the disjoint
* refund requests different (as requests are idempotent and otherwise the 2nd refund might not work).
* @param merchant_priv the private key of the merchant, used to generate signature for refund request
* @param cb the callback to call when a reply for this request is available
* @param cb_cls closure for the above callback
* @return a handle for this request; NULL if the inputs are invalid (i.e.
* signatures fail to verify). In this case, the callback is not called.
*/
struct TALER_EXCHANGE_RefundHandle *
TALER_EXCHANGE_refund (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_Amount *amount,
const struct TALER_Amount *refund_fee,
const struct GNUNET_HashCode *h_contract_terms,
const struct TALER_CoinSpendPublicKeyP *coin_pub,
uint64_t rtransaction_id,
const struct TALER_MerchantPrivateKeyP *merchant_priv,
TALER_EXCHANGE_RefundResultCallback cb,
void *cb_cls);
/**
* Submit a refund request to the exchange and get the exchange's
* response. This API is used by a merchant. Note that
* while we return the response verbatim to the caller for further
* processing, we do already verify that the response is well-formed
* (i.e. that signatures included in the response are all valid). If
* the exchange's reply is not well-formed, we return an HTTP status code
* of zero to @a cb.
*
* The @a exchange must be ready to operate (i.e. have
* finished processing the /keys reply). If this check fails, we do
* NOT initiate the transaction with the exchange and instead return NULL.
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param amount the amount to be refunded; must be larger than the refund fee
* (as that fee is still being subtracted), and smaller than the amount
* (with deposit fee) of the original deposit contribution of this coin
* @param refund_fee fee applicable to this coin for the refund
* @param h_contract_terms hash of the contact of the merchant with the customer that is being refunded
* @param coin_pub coin’s public key of the coin from the original deposit operation
* @param rtransaction_id transaction id for the transaction between merchant and customer (of refunding operation);
* this is needed as we may first do a partial refund and later a full refund. If both
* refunds are also over the same amount, we need the @a rtransaction_id to make the disjoint
* refund requests different (as requests are idempotent and otherwise the 2nd refund might not work).
* @param merchant_pub public key of the merchant
* @param merchant_sig signature affirming the refund from the merchant
* @param cb the callback to call when a reply for this request is available
* @param cb_cls closure for the above callback
* @return a handle for this request; NULL if the inputs are invalid (i.e.
* signatures fail to verify). In this case, the callback is not called.
*/
struct TALER_EXCHANGE_RefundHandle *
TALER_EXCHANGE_refund2 (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_Amount *amount,
const struct TALER_Amount *refund_fee,
const struct GNUNET_HashCode *h_contract_terms,
const struct TALER_CoinSpendPublicKeyP *coin_pub,
uint64_t rtransaction_id,
const struct TALER_MerchantPublicKeyP *merchant_pub,
const struct TALER_MerchantSignatureP *merchant_sig,
TALER_EXCHANGE_RefundResultCallback cb,
void *cb_cls);
/**
* Cancel a refund permission request. This function cannot be used
* on a request handle if a response is already served for it. If
* this function is called, the refund may or may not have happened.
* However, it is fine to try to refund the coin a second time.
*
* @param refund the refund request handle
*/
void
TALER_EXCHANGE_refund_cancel (struct TALER_EXCHANGE_RefundHandle *refund);
/* ********************* /reserve/status *********************** */
/**
* @brief A /reserve/status Handle
*/
struct TALER_EXCHANGE_ReserveStatusHandle;
/**
* Ways how a reserve's balance may change.
*/
enum TALER_EXCHANGE_ReserveTransactionType {
/**
* Deposit into the reserve.
*/
TALER_EXCHANGE_RTT_DEPOSIT,
/**
* Withdrawal from the reserve.
*/
TALER_EXCHANGE_RTT_WITHDRAWAL,
/**
* /payback operation.
*/
TALER_EXCHANGE_RTT_PAYBACK,
/**
* Reserve closed operation.
*/
TALER_EXCHANGE_RTT_CLOSE
};
/**
* @brief Entry in the reserve's transaction history.
*/
struct TALER_EXCHANGE_ReserveHistory
{
/**
* Type of the transaction.
*/
enum TALER_EXCHANGE_ReserveTransactionType type;
/**
* Amount transferred (in or out).
*/
struct TALER_Amount amount;
/**
* Details depending on @e type.
*/
union {
/**
* Information about a deposit that filled this reserve.
* @e type is #TALER_EXCHANGE_RTT_DEPOSIT.
*/
struct {
/**
* Sender account information for the incoming transfer.
*/
json_t *sender_account_details;
/**
* Information that uniquely identifies the wire transfer.
*/
void *wire_reference;
/**
* When did the wire transfer happen?
*/
struct GNUNET_TIME_Absolute timestamp;
/**
* Number of bytes stored in @e wire_reference.
*/
size_t wire_reference_size;
} in_details;
/**
* Signature authorizing the withdrawal for outgoing transaction.
* @e type is #TALER_EXCHANGE_RTT_WITHDRAWAL.
*/
json_t *out_authorization_sig;
/**
* Information provided if the reserve was filled via /payback.
* @e type is #TALER_EXCHANGE_RTT_PAYBACK.
*/
struct {
/**
* Public key of the coin that was paid back.
*/
struct TALER_CoinSpendPublicKeyP coin_pub;
/**
* Signature of the coin of type
* #TALER_SIGNATURE_EXCHANGE_CONFIRM_PAYBACK.
*/
struct TALER_ExchangeSignatureP exchange_sig;
/**
* Public key of the exchange that was used for @e exchange_sig.
*/
struct TALER_ExchangePublicKeyP exchange_pub;
/**
* When did the /payback operation happen?
*/
struct GNUNET_TIME_Absolute timestamp;
} payback_details;
/**
* Information about a close operation of the reserve.
* @e type is #TALER_EXCHANGE_RTT_CLOSE.
*/
struct {
/**
* Receiver account information for the outgoing wire transfer.
*/
json_t *receiver_account_details;
/**
* Wire transfer details for the outgoing wire transfer.
*/
struct TALER_WireTransferIdentifierRawP wtid;
/**
* Signature of the coin of type
* #TALER_SIGNATURE_EXCHANGE_RESERVE_CLOSED.
*/
struct TALER_ExchangeSignatureP exchange_sig;
/**
* Public key of the exchange that was used for @e exchange_sig.
*/
struct TALER_ExchangePublicKeyP exchange_pub;
/**
* When did the wire transfer happen?
*/
struct GNUNET_TIME_Absolute timestamp;
} close_details;
} details;
};
/**
* Callbacks of this type are used to serve the result of submitting a
* reserve status request to a exchange.
*
* @param cls closure
* @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful status request
* 0 if the exchange's reply is bogus (fails to follow the protocol)
* @param ec taler-specific error code, #TALER_EC_NONE on success
* @param[in] json original response in JSON format (useful only for diagnostics)
* @param balance current balance in the reserve, NULL on error
* @param history_length number of entries in the transaction history, 0 on error
* @param history detailed transaction history, NULL on error
*/
typedef void
(*TALER_EXCHANGE_ReserveStatusResultCallback) (void *cls,
unsigned int http_status,
enum TALER_ErrorCode ec,
const json_t *json,
const struct TALER_Amount *balance,
unsigned int history_length,
const struct TALER_EXCHANGE_ReserveHistory *history);
/**
* Submit a request to obtain the transaction history of a reserve
* from the exchange. Note that while we return the full response to the
* caller for further processing, we do already verify that the
* response is well-formed (i.e. that signatures included in the
* response are all valid and add up to the balance). If the exchange's
* reply is not well-formed, we return an HTTP status code of zero to
* @a cb.
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param reserve_pub public key of the reserve to inspect
* @param cb the callback to call when a reply for this request is available
* @param cb_cls closure for the above callback
* @return a handle for this request; NULL if the inputs are invalid (i.e.
* signatures fail to verify). In this case, the callback is not called.
*/
struct TALER_EXCHANGE_ReserveStatusHandle *
TALER_EXCHANGE_reserve_status (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_ReservePublicKeyP *reserve_pub,
TALER_EXCHANGE_ReserveStatusResultCallback cb,
void *cb_cls);
/**
* Cancel a reserve status request. This function cannot be used
* on a request handle if a response is already served for it.
*
* @param rsh the reserve status request handle
*/
void
TALER_EXCHANGE_reserve_status_cancel (struct TALER_EXCHANGE_ReserveStatusHandle *rsh);
/* ********************* /reserve/withdraw *********************** */
/**
* @brief A /reserve/withdraw Handle
*/
struct TALER_EXCHANGE_ReserveWithdrawHandle;
/**
* Callbacks of this type are used to serve the result of submitting a
* withdraw request to a exchange.
*
* @param cls closure
* @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful status request
* 0 if the exchange's reply is bogus (fails to follow the protocol)
* @param ec taler-specific error code, #TALER_EC_NONE on success
* @param sig signature over the coin, NULL on error
* @param full_response full response from the exchange (for logging, in case of errors)
*/
typedef void
(*TALER_EXCHANGE_ReserveWithdrawResultCallback) (void *cls,
unsigned int http_status,
enum TALER_ErrorCode ec,
const struct TALER_DenominationSignature *sig,
const json_t *full_response);
/**
* Withdraw a coin from the exchange using a /reserve/withdraw
* request. This API is typically used by a wallet to withdraw from a
* reserve.
*
* Note that to ensure that no money is lost in case of hardware
* failures, the caller must have committed (most of) the arguments to
* disk before calling, and be ready to repeat the request with the
* same arguments in case of failures.
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param pk kind of coin to create
* @param reserve_priv private key of the reserve to withdraw from
* @param ps secrets of the planchet
* caller must have committed this value to disk before the call (with @a pk)
* @param res_cb the callback to call when the final result for this request is available
* @param res_cb_cls closure for @a res_cb
* @return NULL
* if the inputs are invalid (i.e. denomination key not with this exchange).
* In this case, the callback is not called.
*/
struct TALER_EXCHANGE_ReserveWithdrawHandle *
TALER_EXCHANGE_reserve_withdraw (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_EXCHANGE_DenomPublicKey *pk,
const struct TALER_ReservePrivateKeyP *reserve_priv,
const struct TALER_PlanchetSecretsP *ps,
TALER_EXCHANGE_ReserveWithdrawResultCallback res_cb,
void *res_cb_cls);
/**
* Withdraw a coin from the exchange using a /reserve/withdraw
* request. This API is typically used by a wallet to withdraw a tip
* where the reserve's signature was created by the merchant already.
*
* Note that to ensure that no money is lost in case of hardware
* failures, the caller must have committed (most of) the arguments to
* disk before calling, and be ready to repeat the request with the
* same arguments in case of failures.
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param pk kind of coin to create
* @param reserve_sig signature from the reserve authorizing the withdrawal
* @param reserve_pub public key of the reserve to withdraw from
* @param ps secrets of the planchet
* caller must have committed this value to disk before the call (with @a pk)
* @param res_cb the callback to call when the final result for this request is available
* @param res_cb_cls closure for @a res_cb
* @return NULL
* if the inputs are invalid (i.e. denomination key not with this exchange).
* In this case, the callback is not called.
*/
struct TALER_EXCHANGE_ReserveWithdrawHandle *
TALER_EXCHANGE_reserve_withdraw2 (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_EXCHANGE_DenomPublicKey *pk,
const struct TALER_ReserveSignatureP *reserve_sig,
const struct TALER_ReservePublicKeyP *reserve_pub,
const struct TALER_PlanchetSecretsP *ps,
TALER_EXCHANGE_ReserveWithdrawResultCallback res_cb,
void *res_cb_cls);
/**
* Cancel a withdraw status request. This function cannot be used
* on a request handle if a response is already served for it.
*
* @param sign the withdraw sign request handle
*/
void
TALER_EXCHANGE_reserve_withdraw_cancel (struct TALER_EXCHANGE_ReserveWithdrawHandle *sign);
/* ********************* /refresh/melt+reveal ***************************** */
/**
* Melt (partially spent) coins to obtain fresh coins that are
* unlinkable to the original coin(s). Note that melting more
* than one coin in a single request will make those coins linkable,
* so the safest operation only melts one coin at a time.
*
* This API is typically used by a wallet. Note that to ensure that
* no money is lost in case of hardware failures, is operation does
* not actually initiate the request. Instead, it generates a buffer
* which the caller must store before proceeding with the actual call
* to #TALER_EXCHANGE_refresh_melt() that will generate the request.
*
* This function does verify that the given request data is internally
* consistent. However, the @a melts_sig is only verified if @a
* check_sig is set to #GNUNET_YES, as this may be relatively
* expensive and should be redundant.
*
* Aside from some non-trivial cryptographic operations that might
* take a bit of CPU time to complete, this function returns
* its result immediately and does not start any asynchronous
* processing. This function is also thread-safe.
*
* @param melt_priv private keys of the coin to melt
* @param melt_amount amount specifying how much
* the coin will contribute to the melt (including fee)
* @param melt_sig signatures affirming the
* validity of the public keys corresponding to the
* @a melt_priv private key
* @param melt_pk denomination key information
* record corresponding to the @a melt_sig
* validity of the keys
* @param check_sig verify the validity of the signatures of @a melt_sig
* @param fresh_pks_len length of the @a pks array
* @param fresh_pks array of @a pks_len denominations of fresh coins to create
* @param[out] res_size set to the size of the return value, or 0 on error
* @return NULL
* if the inputs are invalid (i.e. denomination key not with this exchange).
* Otherwise, pointer to a buffer of @a res_size to store persistently
* before proceeding to #TALER_EXCHANGE_refresh_melt().
* Non-null results should be freed using GNUNET_free().
*/
char *
TALER_EXCHANGE_refresh_prepare (const struct TALER_CoinSpendPrivateKeyP *melt_priv,
const struct TALER_Amount *melt_amount,
const struct TALER_DenominationSignature *melt_sig,
const struct TALER_EXCHANGE_DenomPublicKey *melt_pk,
int check_sig,
unsigned int fresh_pks_len,
const struct TALER_EXCHANGE_DenomPublicKey *fresh_pks,
size_t *res_size);
/* ********************* /refresh/melt ***************************** */
/**
* @brief A /refresh/melt Handle
*/
struct TALER_EXCHANGE_RefreshMeltHandle;
/**
* Callbacks of this type are used to notify the application about the
* result of the /refresh/melt stage. If successful, the @a noreveal_index
* should be committed to disk prior to proceeding #TALER_EXCHANGE_refresh_reveal().
*
* @param cls closure
* @param http_status HTTP response code, never #MHD_HTTP_OK (200) as for successful intermediate response this callback is skipped.
* 0 if the exchange's reply is bogus (fails to follow the protocol)
* @param ec taler-specific error code, #TALER_EC_NONE on success
* @param noreveal_index choice by the exchange in the cut-and-choose protocol,
* UINT32_MAX on error
* @param sign_key exchange key used to sign @a full_response, or NULL
* @param full_response full response from the exchange (for logging, in case of errors)
*/
typedef void
(*TALER_EXCHANGE_RefreshMeltCallback) (void *cls,
unsigned int http_status,
enum TALER_ErrorCode ec,
uint32_t noreveal_index,
const struct TALER_ExchangePublicKeyP *sign_key,
const json_t *full_response);
/**
* Submit a refresh melt request to the exchange and get the exchange's
* response.
*
* This API is typically used by a wallet. Note that to ensure that
* no money is lost in case of hardware failures, the provided
* argument should have been constructed using
* #TALER_EXCHANGE_refresh_prepare and committed to persistent storage
* prior to calling this function.
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param refresh_data_length size of the @a refresh_data (returned
* in the `res_size` argument from #TALER_EXCHANGE_refresh_prepare())
* @param refresh_data the refresh data as returned from
#TALER_EXCHANGE_refresh_prepare())
* @param melt_cb the callback to call with the result
* @param melt_cb_cls closure for @a melt_cb
* @return a handle for this request; NULL if the argument was invalid.
* In this case, neither callback will be called.
*/
struct TALER_EXCHANGE_RefreshMeltHandle *
TALER_EXCHANGE_refresh_melt (struct TALER_EXCHANGE_Handle *exchange,
size_t refresh_data_length,
const char *refresh_data,
TALER_EXCHANGE_RefreshMeltCallback melt_cb,
void *melt_cb_cls);
/**
* Cancel a refresh melt request. This function cannot be used
* on a request handle if the callback was already invoked.
*
* @param rmh the refresh handle
*/
void
TALER_EXCHANGE_refresh_melt_cancel (struct TALER_EXCHANGE_RefreshMeltHandle *rmh);
/* ********************* /refresh/reveal ***************************** */
/**
* Callbacks of this type are used to return the final result of
* submitting a refresh request to a exchange. If the operation was
* successful, this function returns the signatures over the coins
* that were remelted. The @a coin_privs and @a sigs arrays give the
* coins in the same order (and should have the same length) in which
* the original request specified the respective denomination keys.
*
* @param cls closure
* @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful status request
* 0 if the exchange's reply is bogus (fails to follow the protocol)
* @param ec taler-specific error code, #TALER_EC_NONE on success
* @param num_coins number of fresh coins created, length of the @a sigs and @a coin_privs arrays, 0 if the operation failed
* @param coin_privs array of @a num_coins private keys for the coins that were created, NULL on error
* @param sigs array of signature over @a num_coins coins, NULL on error
* @param full_response full response from the exchange (for logging, in case of errors)
*/
typedef void
(*TALER_EXCHANGE_RefreshRevealCallback) (void *cls,
unsigned int http_status,
enum TALER_ErrorCode ec,
unsigned int num_coins,
const struct TALER_CoinSpendPrivateKeyP *coin_privs,
const struct TALER_DenominationSignature *sigs,
const json_t *full_response);
/**
* @brief A /refresh/reveal Handle
*/
struct TALER_EXCHANGE_RefreshRevealHandle;
/**
* Submit a /refresh/reval request to the exchange and get the exchange's
* response.
*
* This API is typically used by a wallet. Note that to ensure that
* no money is lost in case of hardware failures, the provided
* arguments should have been committed to persistent storage
* prior to calling this function.
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param refresh_data_length size of the @a refresh_data (returned
* in the `res_size` argument from #TALER_EXCHANGE_refresh_prepare())
* @param refresh_data the refresh data as returned from
#TALER_EXCHANGE_refresh_prepare())
* @param noreveal_index response from the exchange to the
* #TALER_EXCHANGE_refresh_melt() invocation
* @param reveal_cb the callback to call with the final result of the
* refresh operation
* @param reveal_cb_cls closure for the above callback
* @return a handle for this request; NULL if the argument was invalid.
* In this case, neither callback will be called.
*/
struct TALER_EXCHANGE_RefreshRevealHandle *
TALER_EXCHANGE_refresh_reveal (struct TALER_EXCHANGE_Handle *exchange,
size_t refresh_data_length,
const char *refresh_data,
uint32_t noreveal_index,
TALER_EXCHANGE_RefreshRevealCallback reveal_cb,
void *reveal_cb_cls);
/**
* Cancel a refresh reveal request. This function cannot be used
* on a request handle if the callback was already invoked.
*
* @param rrh the refresh reval handle
*/
void
TALER_EXCHANGE_refresh_reveal_cancel (struct TALER_EXCHANGE_RefreshRevealHandle *rrh);
/* ********************* /refresh/link ***************************** */
/**
* @brief A /refresh/link Handle
*/
struct TALER_EXCHANGE_RefreshLinkHandle;
/**
* Callbacks of this type are used to return the final result of
* submitting a /refresh/link request to a exchange. If the operation was
* successful, this function returns the signatures over the coins
* that were created when the original coin was melted.
*
* @param cls closure
* @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful status request
* 0 if the exchange's reply is bogus (fails to follow the protocol)
* @param ec taler-specific error code, #TALER_EC_NONE on success
* @param num_coins number of fresh coins created, length of the @a sigs and @a coin_privs arrays, 0 if the operation failed
* @param coin_privs array of @a num_coins private keys for the coins that were created, NULL on error
* @param sigs array of signature over @a num_coins coins, NULL on error
* @param pubs array of public keys for the @a sigs, NULL on error
* @param full_response full response from the exchange (for logging, in case of errors)
*/
typedef void
(*TALER_EXCHANGE_RefreshLinkCallback) (void *cls,
unsigned int http_status,
enum TALER_ErrorCode ec,
unsigned int num_coins,
const struct TALER_CoinSpendPrivateKeyP *coin_privs,
const struct TALER_DenominationSignature *sigs,
const struct TALER_DenominationPublicKey *pubs,
const json_t *full_response);
/**
* Submit a refresh link request to the exchange and get the
* exchange's response.
*
* This API is typically not used by anyone, it is more a threat
* against those trying to receive a funds transfer by abusing the
* /refresh protocol.
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param coin_priv private key to request link data for
* @param link_cb the callback to call with the useful result of the
* refresh operation the @a coin_priv was involved in (if any)
* @param link_cb_cls closure for @a link_cb
* @return a handle for this request
*/
struct TALER_EXCHANGE_RefreshLinkHandle *
TALER_EXCHANGE_refresh_link (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_CoinSpendPrivateKeyP *coin_priv,
TALER_EXCHANGE_RefreshLinkCallback link_cb,
void *link_cb_cls);
/**
* Cancel a refresh link request. This function cannot be used
* on a request handle if the callback was already invoked.
*
* @param rlh the refresh link handle
*/
void
TALER_EXCHANGE_refresh_link_cancel (struct TALER_EXCHANGE_RefreshLinkHandle *rlh);
/* ********************* /track/transfer *********************** */
/**
* @brief A /track/transfer Handle
*/
struct TALER_EXCHANGE_TrackTransferHandle;
/**
* Function called with detailed wire transfer data, including all
* of the coin transactions that were combined into the wire transfer.
*
* @param cls closure
* @param http_status HTTP status code we got, 0 on exchange protocol violation
* @param ec taler-specific error code, #TALER_EC_NONE on success
* @param sign_key exchange key used to sign @a json, or NULL
* @param json original json reply (may include signatures, those have then been
* validated already)
* @param h_wire hash of the wire transfer address the transfer went to, or NULL on error
* @param execution_time time when the exchange claims to have performed the wire transfer
* @param total_amount total amount of the wire transfer, or NULL if the exchange could
* not provide any @a wtid (set only if @a http_status is #MHD_HTTP_OK)
* @param wire_fee wire fee that was charged by the exchange
* @param details_length length of the @a details array
* @param details array with details about the combined transactions
*/
typedef void
(*TALER_EXCHANGE_TrackTransferCallback)(void *cls,
unsigned int http_status,
enum TALER_ErrorCode ec,
const struct TALER_ExchangePublicKeyP *sign_key,
const json_t *json,
const struct GNUNET_HashCode *h_wire,
struct GNUNET_TIME_Absolute execution_time,
const struct TALER_Amount *total_amount,
const struct TALER_Amount *wire_fee,
unsigned int details_length,
const struct TALER_TrackTransferDetails *details);
/**
* Query the exchange about which transactions were combined
* to create a wire transfer.
*
* @param exchange exchange to query
* @param wtid raw wire transfer identifier to get information about
* @param cb callback to call
* @param cb_cls closure for @a cb
* @return handle to cancel operation
*/
struct TALER_EXCHANGE_TrackTransferHandle *
TALER_EXCHANGE_track_transfer (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_WireTransferIdentifierRawP *wtid,
TALER_EXCHANGE_TrackTransferCallback cb,
void *cb_cls);
/**
* Cancel wire deposits request. This function cannot be used on a request
* handle if a response is already served for it.
*
* @param wdh the wire deposits request handle
*/
void
TALER_EXCHANGE_track_transfer_cancel (struct TALER_EXCHANGE_TrackTransferHandle *wdh);
/* ********************* /track/transaction *********************** */
/**
* @brief A /track/transaction Handle
*/
struct TALER_EXCHANGE_TrackTransactionHandle;
/**
* Function called with detailed wire transfer data.
*
* @param cls closure
* @param http_status HTTP status code we got, 0 on exchange protocol violation
* @param ec taler-specific error code, #TALER_EC_NONE on success
* @param sign_key exchange key used to sign @a json, or NULL
* @param json original json reply (may include signatures, those have then been
* validated already)
* @param wtid wire transfer identifier used by the exchange, NULL if exchange did not
* yet execute the transaction
* @param execution_time actual or planned execution time for the wire transfer
* @param coin_contribution contribution to the @a total_amount of the deposited coin (may be NULL)
*/
typedef void
(*TALER_EXCHANGE_TrackTransactionCallback)(void *cls,
unsigned int http_status,
enum TALER_ErrorCode ec,
const struct TALER_ExchangePublicKeyP *sign_key,
const json_t *json,
const struct TALER_WireTransferIdentifierRawP *wtid,
struct GNUNET_TIME_Absolute execution_time,
const struct TALER_Amount *coin_contribution);
/**
* Obtain the wire transfer details for a given transaction.
*
* @param exchange the exchange to query
* @param merchant_priv the merchant's private key
* @param h_wire hash of merchant's wire transfer details
* @param h_contract_terms hash of the proposal data
* @param coin_pub public key of the coin
* @param cb function to call with the result
* @param cb_cls closure for @a cb
* @return handle to abort request
*/
struct TALER_EXCHANGE_TrackTransactionHandle *
TALER_EXCHANGE_track_transaction (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_MerchantPrivateKeyP *merchant_priv,
const struct GNUNET_HashCode *h_wire,
const struct GNUNET_HashCode *h_contract_terms,
const struct TALER_CoinSpendPublicKeyP *coin_pub,
TALER_EXCHANGE_TrackTransactionCallback cb,
void *cb_cls);
/**
* Cancel deposit wtid request. This function cannot be used on a request
* handle if a response is already served for it.
*
* @param dwh the wire deposits request handle
*/
void
TALER_EXCHANGE_track_transaction_cancel (struct TALER_EXCHANGE_TrackTransactionHandle *dwh);
/**
* Convenience function. Verifies a coin's transaction history as
* returned by the exchange.
*
* @param currency expected currency for the coin
* @param coin_pub public key of the coin
* @param history history of the coin in json encoding
* @param[out] total how much of the coin has been spent according to @a history
* @return #GNUNET_OK if @a history is valid, #GNUNET_SYSERR if not
*/
int
TALER_EXCHANGE_verify_coin_history (const char *currency,
const struct TALER_CoinSpendPublicKeyP *coin_pub,
json_t *history,
struct TALER_Amount *total);
/* ********************* /payback *********************** */
/**
* @brief A /payback Handle
*/
struct TALER_EXCHANGE_PaybackHandle;
/**
* Callbacks of this type are used to return the final result of
* submitting a refresh request to a exchange. If the operation was
* successful, this function returns the signatures over the coins
* that were remelted. The @a coin_privs and @a sigs arrays give the
* coins in the same order (and should have the same length) in which
* the original request specified the respective denomination keys.
*
* @param cls closure
* @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful status request
* 0 if the exchange's reply is bogus (fails to follow the protocol)
* @param ec taler-specific error code, #TALER_EC_NONE on success
* @param amount amount the exchange will wire back for this coin,
* on error the total balance remaining, or NULL
* @param timestamp what time did the exchange receive the /payback request
* @param reserve_pub public key of the reserve receiving the payback
* @param full_response full response from the exchange (for logging, in case of errors)
*/
typedef void
(*TALER_EXCHANGE_PaybackResultCallback) (void *cls,
unsigned int http_status,
enum TALER_ErrorCode ec,
const struct TALER_Amount *amount,
struct GNUNET_TIME_Absolute timestamp,
const struct TALER_ReservePublicKeyP *reserve_pub,
const json_t *full_response);
/**
* Ask the exchange to pay back a coin due to the exchange triggering
* the emergency payback protocol for a given denomination. The value
* of the coin will be refunded to the original customer (without fees).
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param pk kind of coin to pay back
* @param denom_sig signature over the coin by the exchange using @a pk
* @param ps secret internals of the original planchet
* @param payback_cb the callback to call when the final result for this request is available
* @param payback_cb_cls closure for @a payback_cb
* @return NULL
* if the inputs are invalid (i.e. denomination key not with this exchange).
* In this case, the callback is not called.
*/
struct TALER_EXCHANGE_PaybackHandle *
TALER_EXCHANGE_payback (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_EXCHANGE_DenomPublicKey *pk,
const struct TALER_DenominationSignature *denom_sig,
const struct TALER_PlanchetSecretsP *ps,
TALER_EXCHANGE_PaybackResultCallback payback_cb,
void *payback_cb_cls);
/**
* Cancel a payback request. This function cannot be used on a
* request handle if the callback was already invoked.
*
* @param ph the payback handle
*/
void
TALER_EXCHANGE_payback_cancel (struct TALER_EXCHANGE_PaybackHandle *ph);
#endif /* _TALER_EXCHANGE_SERVICE_H */