frostfs-contract/balance/balance_contract.go

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package balance
import (
"git.frostfs.info/TrueCloudLab/frostfs-contract/common"
"github.com/nspcc-dev/neo-go/pkg/interop"
"github.com/nspcc-dev/neo-go/pkg/interop/iterator"
"github.com/nspcc-dev/neo-go/pkg/interop/native/management"
"github.com/nspcc-dev/neo-go/pkg/interop/native/std"
"github.com/nspcc-dev/neo-go/pkg/interop/runtime"
"github.com/nspcc-dev/neo-go/pkg/interop/storage"
)
type (
// Token holds all token info.
Token struct {
// Ticker symbol
Symbol string
// Amount of decimals
Decimals int
// Storage key for circulation value
CirculationKey string
}
// Account structure stores metadata of each FrostFS balance account.
Account struct {
// Active balance
Balance int
// Until valid for lock accounts
Until int
// Parent field used in lock accounts, used to return assets back if
// account wasn't burnt.
Parent []byte
}
// account is a stored view of Account with fixed int size
account struct {
Balance []byte
Until []byte
Parent []byte
}
)
const (
symbol = "FROSTFS"
decimals = 12
circulation = "MainnetGAS"
netmapContractKey = "netmapScriptHash"
containerContractKey = "containerScriptHash"
)
var token Token
func createToken() Token {
return Token{
Symbol: symbol,
Decimals: decimals,
CirculationKey: circulation,
}
}
func init() {
token = createToken()
}
func _deploy(data interface{}, isUpdate bool) {
ctx := storage.GetContext()
if isUpdate {
args := data.([]interface{})
common.CheckVersion(args[len(args)-1].(int))
return
}
args := data.(struct {
addrNetmap interop.Hash160
addrContainer interop.Hash160
})
if len(args.addrNetmap) != interop.Hash160Len || len(args.addrContainer) != interop.Hash160Len {
panic("incorrect length of contract script hash")
}
storage.Put(ctx, netmapContractKey, args.addrNetmap)
storage.Put(ctx, containerContractKey, args.addrContainer)
runtime.Log("balance contract initialized")
}
// Update method updates contract source code and manifest. It can be invoked
// only by committee.
func Update(script []byte, manifest []byte, data interface{}) {
if !common.HasUpdateAccess() {
panic("only committee can update contract")
}
management.UpdateWithData(script, manifest, common.AppendVersion(data))
runtime.Log("balance contract updated")
}
// Symbol is a NEP-17 standard method that returns FROSTFS token symbol.
func Symbol() string {
return token.Symbol
}
// Decimals is a NEP-17 standard method that returns precision of FrostFS
// balances.
func Decimals() int {
return token.Decimals
}
// TotalSupply is a NEP-17 standard method that returns total amount of main
// chain GAS in FrostFS network.
func TotalSupply() int {
ctx := storage.GetReadOnlyContext()
return token.getSupply(ctx)
}
// BalanceOf is a NEP-17 standard method that returns FrostFS balance of the specified
// account.
func BalanceOf(account interop.Hash160) int {
ctx := storage.GetReadOnlyContext()
return token.balanceOf(ctx, account)
}
// Transfer is a NEP-17 standard method that transfers FrostFS balance from one
// account to another. It can be invoked only by the account owner.
//
// It produces Transfer and TransferX notifications. TransferX notification
// will have empty details field.
func Transfer(from, to interop.Hash160, amount int, data interface{}) bool {
ctx := storage.GetContext()
return token.transfer(ctx, from, to, amount, false, nil)
}
// TransferX is a method for FrostFS balance to be transferred from one account to
// another. It can be invoked by the account owner or by Alphabet nodes.
//
// It produces Transfer and TransferX notifications.
//
// TransferX method expands Transfer method by having extra details argument.
// TransferX method also allows to transfer assets by Alphabet nodes of the
// Inner Ring with multisignature.
func TransferX(from, to interop.Hash160, amount int, details []byte) {
ctx := storage.GetContext()
common.CheckAlphabetWitness()
result := token.transfer(ctx, from, to, amount, true, details)
if !result {
panic("can't transfer assets")
}
runtime.Log("successfully transferred assets")
}
// Lock is a method that transfers assets from a user account to the lock account
// related to the user. It can be invoked only by Alphabet nodes of the Inner Ring.
//
// It produces Lock, Transfer and TransferX notifications.
//
// Lock method is invoked by Alphabet nodes of the Inner Ring when they process
// Withdraw notification from FrostFS contract. This should transfer assets
// to a new lock account that won't be used for anything beside Unlock and Burn.
func Lock(txDetails []byte, from, to interop.Hash160, amount, until int) {
ctx := storage.GetContext()
common.CheckAlphabetWitness()
details := common.LockTransferDetails(txDetails)
lockAccount := Account{
Balance: 0,
Until: until,
Parent: from,
}
setAccount(ctx, to, lockAccount)
result := token.transfer(ctx, from, to, amount, true, details)
if !result {
// consider using `return false` to remove votes
panic("can't lock funds")
}
runtime.Log("created lock account")
runtime.Notify("Lock", txDetails, from, to, amount, until)
}
// NewEpoch is a method that checks timeout on lock accounts and returns assets
// if lock is not available anymore. It can be invoked only by NewEpoch method
// of Netmap contract.
//
// It produces Transfer and TransferX notifications.
func NewEpoch(epochNum int) {
ctx := storage.GetContext()
common.CheckAlphabetWitness()
it := storage.Find(ctx, []byte{}, storage.KeysOnly)
for iterator.Next(it) {
addr := iterator.Value(it).(interop.Hash160) // it MUST BE `storage.KeysOnly`
if len(addr) != interop.Hash160Len {
continue
}
acc := getAccount(ctx, addr)
if acc.Until == 0 {
continue
}
if epochNum >= acc.Until {
details := common.UnlockTransferDetails(epochNum)
// return assets back to the parent
token.transfer(ctx, addr, acc.Parent, acc.Balance, true, details)
}
}
}
// Mint is a method that transfers assets to a user account from an empty account.
// It can be invoked only by Alphabet nodes of the Inner Ring.
//
// It produces Mint, Transfer and TransferX notifications.
//
// Mint method is invoked by Alphabet nodes of the Inner Ring when they process
// Deposit notification from FrostFS contract. Before that, Alphabet nodes should
// synchronize precision of mainchain GAS contract and Balance contract.
// Mint increases total supply of NEP-17 compatible FrostFS token.
func Mint(to interop.Hash160, amount int, txDetails []byte) {
ctx := storage.GetContext()
common.CheckAlphabetWitness()
details := common.MintTransferDetails(txDetails)
ok := token.transfer(ctx, nil, to, amount, true, details)
if !ok {
panic("can't transfer assets")
}
supply := token.getSupply(ctx)
supply = supply + amount
storage.Put(ctx, token.CirculationKey, supply)
runtime.Log("assets were minted")
runtime.Notify("Mint", to, amount)
}
// Burn is a method that transfers assets from a user account to an empty account.
// It can be invoked only by Alphabet nodes of the Inner Ring.
//
// It produces Burn, Transfer and TransferX notifications.
//
// Burn method is invoked by Alphabet nodes of the Inner Ring when they process
// Cheque notification from FrostFS contract. It means that locked assets have been
// transferred to the user in the mainchain, therefore the lock account should be destroyed.
// Before that, Alphabet nodes should synchronize precision of mainchain GAS
// contract and Balance contract. Burn decreases total supply of NEP-17
// compatible FrostFS token.
func Burn(from interop.Hash160, amount int, txDetails []byte) {
ctx := storage.GetContext()
common.CheckAlphabetWitness()
details := common.BurnTransferDetails(txDetails)
ok := token.transfer(ctx, from, nil, amount, true, details)
if !ok {
panic("can't transfer assets")
}
supply := token.getSupply(ctx)
if supply < amount {
panic("negative supply after burn")
}
supply = supply - amount
storage.Put(ctx, token.CirculationKey, supply)
runtime.Log("assets were burned")
runtime.Notify("Burn", from, amount)
}
// Version returns the version of the contract.
func Version() int {
return common.Version
}
// getSupply gets the token totalSupply value from VM storage.
func (t Token) getSupply(ctx storage.Context) int {
supply := storage.Get(ctx, t.CirculationKey)
if supply != nil {
return supply.(int)
}
return 0
}
// BalanceOf gets the token balance of a specific address.
func (t Token) balanceOf(ctx storage.Context, holder interop.Hash160) int {
acc := getAccount(ctx, holder)
return acc.Balance
}
func (t Token) transfer(ctx storage.Context, from, to interop.Hash160, amount int, innerRing bool, details []byte) bool {
amountFrom, ok := t.canTransfer(ctx, from, to, amount, innerRing)
if !ok {
return false
}
if len(from) == 20 {
if amountFrom.Balance == amount {
storage.Delete(ctx, from)
} else {
amountFrom.Balance = amountFrom.Balance - amount // neo-go#953
setAccount(ctx, from, amountFrom)
}
}
if len(to) == 20 {
amountTo := getAccount(ctx, to)
amountTo.Balance = amountTo.Balance + amount // neo-go#953
setAccount(ctx, to, amountTo)
}
runtime.Notify("Transfer", from, to, amount)
runtime.Notify("TransferX", from, to, amount, details)
return true
}
// canTransfer returns the amount it can transfer.
func (t Token) canTransfer(ctx storage.Context, from, to interop.Hash160, amount int, innerRing bool) (Account, bool) {
emptyAcc := Account{}
if !innerRing {
if len(to) != interop.Hash160Len || !isUsableAddress(from) {
runtime.Log("bad script hashes")
return emptyAcc, false
}
} else if len(from) == 0 {
return emptyAcc, true
}
amountFrom := getAccount(ctx, from)
if amountFrom.Balance < amount {
runtime.Log("not enough assets")
return emptyAcc, false
}
// return amountFrom value back to transfer, reduces extra Get
return amountFrom, true
}
// isUsableAddress checks if the sender is either a correct NEO address or SC address.
func isUsableAddress(addr interop.Hash160) bool {
if len(addr) == 20 {
if runtime.CheckWitness(addr) {
return true
}
// Check if a smart contract is calling script hash
callingScriptHash := runtime.GetCallingScriptHash()
if common.BytesEqual(callingScriptHash, addr) {
return true
}
}
return false
}
func getAccount(ctx storage.Context, key interface{}) Account {
data := storage.Get(ctx, key)
if data != nil {
acc := std.Deserialize(data.([]byte)).(account)
return Account{
Balance: common.FromFixedWidth64(acc.Balance),
Until: common.FromFixedWidth64(acc.Until),
Parent: acc.Parent,
}
}
return Account{}
}
func setAccount(ctx storage.Context, key interface{}, acc Account) {
common.SetSerialized(ctx, key, account{
Balance: common.ToFixedWidth64(acc.Balance),
Until: common.ToFixedWidth64(acc.Until),
Parent: acc.Parent,
})
}