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interface.go
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// This code is available on the terms of the project LICENSE.md file,
// also available online at https://blueoakcouncil.org/license/1.0.0.
package asset
import (
"context"
"time"
"decred.org/dcrdex/dex"
)
// CoinNotFoundError is returned when a coin cannot be found, either because it
// has been spent or it never existed. This error may be returned from
// AuditContract, Refund or Redeem as those methods expect the provided coin to
// exist and be unspent.
const (
CoinNotFoundError = dex.ErrorKind("coin not found")
ErrRequestTimeout = dex.ErrorKind("request timeout")
ErrConnectionDown = dex.ErrorKind("wallet not connected")
)
// WalletInfo is auxiliary information about an ExchangeWallet.
type WalletInfo struct {
// Name is the display name for the currency, e.g. "Decred"
Name string `json:"name"`
// Units is the unit used for the smallest (integer) denomination of the
// currency, in plural form e.g. atoms, Satoshis.
Units string `json:"units"`
// Version is the Wallet's version number, which is used to signal when
// major changes are made to internal details such as coin ID encoding and
// contract structure that must be common to a server's.
Version uint32
// DefaultConfigPath is the default file path that the Wallet uses for its
// configuration file.
DefaultConfigPath string `json:"configpath"`
// ConfigOpts is a slice of expected Wallet config options, with the display
// name, config key (for parsing the option from a config file/text) and
// description for each option. This can be used to request config info from
// users e.g. via dynamically generated GUI forms.
ConfigOpts []*ConfigOption `json:"configopts"`
}
// ConfigOption is a wallet configuration option.
type ConfigOption struct {
Key string `json:"key"`
DisplayName string `json:"displayname"`
Description string `json:"description"`
DefaultValue interface{} `json:"default"`
NoEcho bool `json:"noecho"`
IsBoolean bool `json:"isboolean"`
}
// WalletConfig is the configuration settings for the wallet. WalletConfig
// is passed to the wallet constructor.
type WalletConfig struct {
// Settings is the key-value store of wallet connection parameters. The
// Settings are supplied by the user according the the WalletInfo's
// ConfigOpts.
Settings map[string]string
// TipChange is a function that will be called when the blockchain
// monitoring loop detects a new block. If the error supplied is nil, the
// client should check the confirmations on any negotiating swaps to see if
// action is needed. If the error is non-nil, the wallet monitoring loop
// encountered an error while retrieving tip information. This function
// should not be blocking, and Wallet implementations should not rely on any
// specific side effect of the function call.
TipChange func(error)
}
// Wallet is a common interface to be implemented by cryptocurrency wallet
// software.
type Wallet interface {
// It should be assumed that once disconnected, subsequent Connect calls
// will fail, requiring a new Wallet instance.
dex.Connector
// Info returns a set of basic information about the wallet.
Info() *WalletInfo
// Balance should return the balance of the wallet, categorized by
// available, immature, and locked. Balance takes a list of minimum
// confirmations for which to calculate maturity, and returns a list of
// corresponding *Balance.
Balance() (*Balance, error)
// FundOrder selects coins for use in an order. The coins will be locked,
// and will not be returned in subsequent calls to FundOrder or calculated
// in calls to Available, unless they are unlocked with ReturnCoins. The
// returned []dex.Bytes contains the redeem scripts for the selected coins.
// Equal number of coins and redeemed scripts must be returned. A nil or
// empty dex.Bytes should be appended to the redeem scripts collection for
// coins with no redeem script.
FundOrder(*Order) (coins Coins, redeemScripts []dex.Bytes, err error)
// MaxOrder generates information about the maximum order size and
// associated fees that the wallet can support for the specified DEX. The
// fees are an estimate based on current network conditions, and will be <=
// the fees associated with the Asset.MaxFeeRate. For quote assets, lotSize
// will be an estimate based on current market conditions. lotSize should
// not be zero.
MaxOrder(lotSize, feeSuggestion uint64, nfo *dex.Asset) (*SwapEstimate, error)
// PreSwap gets a pre-swap estimate for the specified order size.
PreSwap(*PreSwapForm) (*PreSwap, error)
// PreRedeem gets a pre-redeem estimate for the specified order size.
PreRedeem(*PreRedeemForm) (*PreRedeem, error)
// ReturnCoins unlocks coins. This would be necessary in the case of a
// canceled order.
ReturnCoins(Coins) error
// FundingCoins gets funding coins for the coin IDs. The coins are locked.
// This method might be called to reinitialize an order from data stored
// externally. This method will only return funding coins, e.g. unspent
// transaction outputs.
FundingCoins([]dex.Bytes) (Coins, error)
// Swap sends the swaps in a single transaction. The Receipts returned can
// be used to refund a failed transaction. The Input coins are unlocked where
// necessary to ensure accurate balance reporting in cases where the wallet
// includes spent coins as part of the locked balance just because they were
// previously locked.
Swap(*Swaps) (receipts []Receipt, changeCoin Coin, feesPaid uint64, err error)
// Redeem sends the redemption transaction, which may contain more than one
// redemption. The input coin IDs and the output Coin are returned.
Redeem(redeems *RedeemForm) (ins []dex.Bytes, out Coin, feesPaid uint64, err error)
// SignMessage signs the coin ID with the private key associated with the
// specified Coin. A slice of pubkeys required to spend the Coin and a
// signature for each pubkey are returned.
SignMessage(Coin, dex.Bytes) (pubkeys, sigs []dex.Bytes, err error)
// AuditContract retrieves information about a swap contract on the
// blockchain. This would be used to verify the counter-party's contract
// during a swap. If the coin cannot be found for the coin ID, the
// ExchangeWallet should return CoinNotFoundError. This enables the client
// to properly handle network latency.
AuditContract(coinID, contract, txData dex.Bytes) (*AuditInfo, error)
// LocktimeExpired returns true if the specified contract's locktime has
// expired, making it possible to issue a Refund. The contract expiry time
// is also returned, but reaching this time does not necessarily mean the
// contract can be refunded since assets have different rules to satisfy the
// lock. For example, in Bitcoin the median of the last 11 blocks must be
// past the expiry time, not the current time.
LocktimeExpired(contract dex.Bytes) (bool, time.Time, error)
// FindRedemption watches for the input that spends the specified contract
// coin, and returns the spending input and the contract's secret key when
// it finds a spender.
// For typical blockchains, every input of every block tx (starting at the
// contract block) will need to be scanned until a spending input is found.
//
// FindRedemption is necessary to deal with the case of a maker redeeming but
// not forwarding their redemption information. The DEX does not monitor for
// this case. While it will result in the counter-party being penalized, the
// input still needs to be found so the swap can be completed.
//
// NOTE: This could potentially be a long and expensive operation if performed
// long after the swap is broadcast; might be better executed from a goroutine.
FindRedemption(ctx context.Context, coinID dex.Bytes) (redemptionCoin, secret dex.Bytes, err error)
// Refund refunds a contract. This can only be used after the time lock has
// expired AND if the contract has not been redeemed/refunded.
// NOTE: The contract cannot be retrieved from the unspent coin info as the
// wallet does not store it, even though it was known when the init transaction
// was created. The client should store this information for persistence across
// sessions.
Refund(coinID, contract dex.Bytes) (dex.Bytes, error)
// Address returns an address for the exchange wallet.
Address() (string, error)
// OwnsAddress indicates if an address belongs to the wallet.
OwnsAddress(address string) (bool, error)
// Unlock unlocks the exchange wallet.
Unlock(pw string) error
// Lock locks the exchange wallet.
Lock() error
// Locked will be true if the wallet is currently locked.
Locked() bool
// PayFee sends the dex registration fee. Transaction fees are in addition to
// the registration fee, and the fee rate is taken from the DEX configuration.
PayFee(address string, feeAmt uint64) (Coin, error)
// Confirmations gets the number of confirmations for the specified coin ID.
// If the coin is not unspent, and is not known to this wallet,
// Confirmations may return an error. The value of spent should be ignored
// if err is non-nil, but Wallet implementations should return spent = false
// anyway.
Confirmations(ctx context.Context, id dex.Bytes) (confs uint32, spent bool, err error)
// Withdraw withdraws funds to the specified address. Fees are subtracted from
// the value.
Withdraw(address string, value uint64) (Coin, error)
// ValidateSecret checks that the secret hashes to the secret hash.
ValidateSecret(secret, secretHash []byte) bool
// SyncStatus is information about the blockchain sync status.
SyncStatus() (synced bool, progress float32, err error)
}
// Balance is categorized information about a wallet's balance.
type Balance struct {
// Available is the balance that is available for trading immediately.
Available uint64 `json:"available"`
// Immature is the balance that is not ready, but will be after some
// confirmations.
Immature uint64 `json:"immature"`
// Locked is the total amount locked in the wallet which includes but
// is not limited to funds locked for swap but not actually swapped yet.
Locked uint64 `json:"locked"`
}
// Coin is some amount of spendable asset. Coin provides the information needed
// to locate the unspent value on the blockchain.
type Coin interface {
// ID is a unique identifier for this coin.
ID() dex.Bytes
// String is a string representation of the coin.
String() string
// Value is the available quantity, in atoms/satoshi.
Value() uint64
}
// Coins a collection of coins as returned by Fund.
type Coins []Coin
// Receipt holds information about a sent swap contract.
type Receipt interface {
// Expiration is the time lock expiration.
Expiration() time.Time
// Coin is the contract's coin.
Coin() Coin
// Contract is the contract script.
Contract() dex.Bytes
// String provides a human-readable representation of the contract's Coin.
String() string
}
// AuditInfo is audit information about a swap contract needed to audit the
// contract.
type AuditInfo struct {
// Recipient is the string-encoded recipient address.
Recipient string
// Expiration is the unix timestamp of the contract time lock expiration.
Expiration time.Time
// Coin is the coin that contains the contract.
Coin Coin
// Contract is the contract script.
Contract dex.Bytes
// SecretHash is the contract's secret hash.
SecretHash dex.Bytes
}
// INPUT TYPES
// The types below will be used by the client as inputs for the methods exposed
// by the wallet.
// Swaps is the details needed to broadcast a swap contract(s).
type Swaps struct {
// Inputs are the Coins being spent.
Inputs Coins
// Contract is the contract data.
Contracts []*Contract
// FeeRate is the required fee rate in atoms/byte.
FeeRate uint64
// LockChange can be set to true if the change should be locked for
// subsequent matches.
LockChange bool
}
// Contract is a swap contract.
type Contract struct {
// Address is the receiving address.
Address string
// Value is the amount being traded.
Value uint64
// SecretHash is the hash of the secret key.
SecretHash dex.Bytes
// LockTime is the contract lock time.
LockTime uint64
}
// Redemption is a redemption transaction that spends a counter-party's swap
// contract.
type Redemption struct {
// Spends is the AuditInfo for the swap output being spent.
Spends *AuditInfo
// Secret is the secret key needed to satisfy the swap contract.
Secret dex.Bytes
}
// RedeemForm is a group of Redemptions. The struct will be
// expanded in in-progress work to accommodate order-time options.
type RedeemForm struct {
Redemptions []*Redemption
// FeeSuggestion is a suggested fee from the server. For redemptions, the
// suggestion is provided as a convenience for wallets without full
// chain backing which cannot get an estimate otherwise. Since this is the
// redemption, there is no obligation on the client to use the fee
// suggestion in any way, but obviously fees that are too low may result in
// the redemption getting stuck in mempool.
FeeSuggestion uint64
}
// Order is order details needed for FundOrder.
type Order struct {
// Value is the amount required to satisfy the order. The Value does not
// include fees. Fees will be calculated internally based on the number of
// possible swaps (MaxSwapCount) and the exchange's configuration
// (DEXConfig).
Value uint64
// MaxSwapCount is the number of lots in the order, which is also the
// maximum number of transaction that an order could potentially generate
// in a worst-case scenario of all 1-lot matches. Note that if requesting
// funding for the quote asset's wallet, the number of lots will not be
// Value / DEXConfig.LotSize, because an order is quantified in the base
// asset, so lots is always (order quantity) / (base asset lot size).
MaxSwapCount uint64 // uint64 for compatibility with quantity and lot size.
// DEXConfig holds values specific to and provided by a particular server.
// Info about fee rates and swap transaction sizes is used internally to
// calculate the funding required to cover fees.
DEXConfig *dex.Asset
// Immediate should be set to true if this is for an order that is not a
// standing order, likely a market order or a limit order with immediate
// time-in-force.
Immediate bool
// FeeSuggestion is a suggested fee from the server. If a split transaction
// is used, the fee rate used should be at least the suggested fee, else
// zero-conf coins might be rejected.
FeeSuggestion uint64
}
// SwapEstimate is an estimate of the fees and locked amounts associated with
// an order.
type SwapEstimate struct {
// Lots is the number of lots in the order.
Lots uint64 `json:"lots"`
// Value is the total value of the order.
Value uint64 `json:"value"`
// MaxFees is the maximum possible fees that can be assessed for the order's
// swaps.
MaxFees uint64 `json:"maxFees"`
// RealisticWorstCase is an estimation of the fees that might be assessed in
// a worst-case scenario of 1 tx per 1 lot match, but at the prevailing fee
// rate estimate.
RealisticWorstCase uint64 `json:"realisticWorstCase"`
// RealisticBestCase is an estimation of the fees that might be assessed in
// a best-case scenario of 1 tx and 1 output for the entire order.
RealisticBestCase uint64 `json:"realisticBestCase"`
// Locked is the amount that will be locked if this order is
// subsequently placed.
Locked uint64 `json:"locked"`
}
// RedeemEstimate is an estimate of the range of fees that might realistically
// be assessed to the redemption transaction.
type RedeemEstimate struct {
// RealisticBestCase is the best-case scenario fees of a single transaction
// with a match covering the entire order, at the prevailing fee rate.
RealisticBestCase uint64 `json:"realisticBestCase"`
// RealisticWorstCase is the worst-case scenario fees of all 1-lot matches,
// each with their own call to Redeem.
RealisticWorstCase uint64 `json:"realisticWorstCase"`
}
// PreSwapForm can be used to get a swap fees estimate.
type PreSwapForm struct {
// LotSize is the lot size for the calculation. For quote assets, LotSize
// should be based on either the user's limit order rate, or some measure
// of the current market rate.
LotSize uint64
// Lots is the number of lots in the order.
Lots uint64
// AssetConfig is the dex's asset configuration info.
AssetConfig *dex.Asset
// Immediate should be set to true if this is for an order that is not a
// standing order, likely a market order or a limit order with immediate
// time-in-force.
Immediate bool
// FeeSuggestion is a suggested fee from the server. If a split transaction
// is used, the fee rate used should be at least the suggested fee, else
// zero-conf coins might be rejected.
FeeSuggestion uint64
}
// SwapOption is an OrderEstimate and it's associated ConfigOption.
type SwapOption struct {
ConfigOption
// Estimate is the OrderEstimate for an order with the specified
// option values.
Estimate *SwapEstimate
}
// PreSwap is a SwapEstimate returned from Wallet.PreSwap. The struct will be
// expanded in in-progress work to accommodate order-time options.
type PreSwap struct {
Estimate *SwapEstimate `json:"estimate"`
}
// PreRedeemForm can be used to get a redemption estimate.
type PreRedeemForm struct {
// LotSize is the lot size for the calculation. For quote assets, LotSize
// should be based on either the user's limit order rate, or some measure
// of the current market rate.
LotSize uint64
// Lots is the number of lots in the order.
Lots uint64
// FeeSuggestion is a suggested fee from the server.
FeeSuggestion uint64
}
// PreRedeem is an estimate of the fees for redemption. The struct will be
// expanded in in-progress work to accommodate order-time options.
type PreRedeem struct {
Estimate *RedeemEstimate `json:"estimate"`
}