package native import ( "errors" "fmt" "math" "math/big" "sync" "github.com/nspcc-dev/neo-go/pkg/core/dao" "github.com/nspcc-dev/neo-go/pkg/core/interop" "github.com/nspcc-dev/neo-go/pkg/core/interop/contract" "github.com/nspcc-dev/neo-go/pkg/core/interop/runtime" "github.com/nspcc-dev/neo-go/pkg/core/state" "github.com/nspcc-dev/neo-go/pkg/core/storage" "github.com/nspcc-dev/neo-go/pkg/core/transaction" "github.com/nspcc-dev/neo-go/pkg/crypto/keys" "github.com/nspcc-dev/neo-go/pkg/smartcontract" "github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest" "github.com/nspcc-dev/neo-go/pkg/util" "github.com/nspcc-dev/neo-go/pkg/vm" "github.com/nspcc-dev/neo-go/pkg/vm/stackitem" ) // Notary represents Notary native contract. type Notary struct { interop.ContractMD GAS *GAS Desig *Designate lock sync.RWMutex // isValid defies whether cached values were changed during the current // consensus iteration. If false, these values will be updated after // blockchain DAO persisting. If true, we can safely use cached values. isValid bool maxNotValidBeforeDelta uint32 } const ( notaryName = "Notary" notaryContractID = reservedContractID - 1 // NotaryVerificationPrice is the price of `verify` Notary method. NotaryVerificationPrice = 100_0000 // prefixDeposit is a prefix for storing Notary deposits. prefixDeposit = 1 defaultDepositDeltaTill = 5760 defaultMaxNotValidBeforeDelta = 140 // 20 rounds for 7 validators, a little more than half an hour ) var maxNotValidBeforeDeltaKey = []byte{10} // newNotary returns Notary native contract. func newNotary() *Notary { n := &Notary{ContractMD: *interop.NewContractMD(notaryName)} n.ContractID = notaryContractID desc := newDescriptor("onPayment", smartcontract.VoidType, manifest.NewParameter("from", smartcontract.Hash160Type), manifest.NewParameter("amount", smartcontract.IntegerType), manifest.NewParameter("data", smartcontract.AnyType)) md := newMethodAndPrice(n.onPayment, 100_0000, smartcontract.WriteStates) n.AddMethod(md, desc) desc = newDescriptor("lockDepositUntil", smartcontract.BoolType, manifest.NewParameter("address", smartcontract.Hash160Type), manifest.NewParameter("till", smartcontract.IntegerType)) md = newMethodAndPrice(n.lockDepositUntil, 100_0000, smartcontract.WriteStates) n.AddMethod(md, desc) desc = newDescriptor("withdraw", smartcontract.BoolType, manifest.NewParameter("from", smartcontract.Hash160Type), manifest.NewParameter("to", smartcontract.Hash160Type)) md = newMethodAndPrice(n.withdraw, 100_0000, smartcontract.WriteStates) n.AddMethod(md, desc) desc = newDescriptor("balanceOf", smartcontract.IntegerType, manifest.NewParameter("addr", smartcontract.Hash160Type)) md = newMethodAndPrice(n.balanceOf, 100_0000, smartcontract.ReadStates) n.AddMethod(md, desc) desc = newDescriptor("expirationOf", smartcontract.IntegerType, manifest.NewParameter("addr", smartcontract.Hash160Type)) md = newMethodAndPrice(n.expirationOf, 100_0000, smartcontract.ReadStates) n.AddMethod(md, desc) desc = newDescriptor("verify", smartcontract.BoolType, manifest.NewParameter("signature", smartcontract.SignatureType)) md = newMethodAndPrice(n.verify, 100_0000, smartcontract.ReadStates) n.AddMethod(md, desc) desc = newDescriptor("getMaxNotValidBeforeDelta", smartcontract.IntegerType) md = newMethodAndPrice(n.getMaxNotValidBeforeDelta, 100_0000, smartcontract.ReadStates) n.AddMethod(md, desc) desc = newDescriptor("setMaxNotValidBeforeDelta", smartcontract.BoolType, manifest.NewParameter("value", smartcontract.IntegerType)) md = newMethodAndPrice(n.setMaxNotValidBeforeDelta, 300_0000, smartcontract.WriteStates) n.AddMethod(md, desc) return n } // Metadata implements Contract interface. func (n *Notary) Metadata() *interop.ContractMD { return &n.ContractMD } // Initialize initializes Notary native contract and implements Contract interface. func (n *Notary) Initialize(ic *interop.Context) error { n.isValid = true n.maxNotValidBeforeDelta = defaultMaxNotValidBeforeDelta return nil } // OnPersist implements Contract interface. func (n *Notary) OnPersist(ic *interop.Context) error { var ( nFees int64 notaries keys.PublicKeys err error ) for _, tx := range ic.Block.Transactions { if tx.HasAttribute(transaction.NotaryAssistedT) { if notaries == nil { notaries, err = n.GetNotaryNodes(ic.DAO) if err != nil { return fmt.Errorf("failed to get notary nodes: %w", err) } } nKeys := tx.GetAttributes(transaction.NotaryAssistedT)[0].Value.(*transaction.NotaryAssisted).NKeys nFees += int64(nKeys) + 1 if tx.Sender() == n.Hash { payer := tx.Signers[1] balance := n.GetDepositFor(ic.DAO, payer.Account) balance.Amount.Sub(balance.Amount, big.NewInt(tx.SystemFee+tx.NetworkFee)) if balance.Amount.Sign() == 0 { err := n.removeDepositFor(ic.DAO, payer.Account) if err != nil { return fmt.Errorf("failed to remove an empty deposit for %s from storage: %w", payer.Account.StringBE(), err) } } else { err := n.putDepositFor(ic.DAO, balance, payer.Account) if err != nil { return fmt.Errorf("failed to update deposit for %s: %w", payer.Account.StringBE(), err) } } } } } if nFees == 0 { return nil } singleReward := calculateNotaryReward(nFees, len(notaries)) for _, notary := range notaries { n.GAS.mint(ic, notary.GetScriptHash(), singleReward, false) } return nil } // OnPersistEnd updates cached Policy values if they've been changed func (n *Notary) OnPersistEnd(dao dao.DAO) error { if n.isValid { return nil } n.lock.Lock() defer n.lock.Unlock() n.maxNotValidBeforeDelta = getUint32WithKey(n.ContractID, dao, maxNotValidBeforeDeltaKey, defaultMaxNotValidBeforeDelta) n.isValid = true return nil } // PostPersist implements Contract interface. func (n *Notary) PostPersist(ic *interop.Context) error { return nil } // onPayment records deposited amount as belonging to "from" address with a lock // till the specified chain's height. func (n *Notary) onPayment(ic *interop.Context, args []stackitem.Item) stackitem.Item { if h := ic.VM.GetCallingScriptHash(); h != n.GAS.Hash { panic(fmt.Errorf("only GAS can be accepted for deposit, got %s", h.StringBE())) } from := toUint160(args[0]) to := from amount := toBigInt(args[1]) data, ok := args[2].(*stackitem.Array) if !ok || len(data.Value().([]stackitem.Item)) != 2 { panic(errors.New("`data` parameter should be an array of 2 elements")) } additionalParams := data.Value().([]stackitem.Item) if !additionalParams[0].Equals(stackitem.Null{}) { to = toUint160(additionalParams[0]) } allowedChangeTill := ic.Tx.Sender() == to currentHeight := ic.Chain.BlockHeight() deposit := n.GetDepositFor(ic.DAO, to) till := toUint32(additionalParams[1]) if till < currentHeight { panic(fmt.Errorf("`till` shouldn't be less then the chain's height %d", currentHeight)) } if deposit != nil && till < deposit.Till { panic(fmt.Errorf("`till` shouldn't be less then the previous value %d", deposit.Till)) } if deposit == nil { if amount.Cmp(big.NewInt(2*transaction.NotaryServiceFeePerKey)) < 0 { panic(fmt.Errorf("first deposit can not be less then %d, got %d", 2*transaction.NotaryServiceFeePerKey, amount.Int64())) } deposit = &state.Deposit{ Amount: new(big.Int), } if !allowedChangeTill { till = currentHeight + defaultDepositDeltaTill } } else if !allowedChangeTill { // only deposit's owner is allowed to set or update `till` till = deposit.Till } deposit.Amount.Add(deposit.Amount, amount) deposit.Till = till if err := n.putDepositFor(ic.DAO, deposit, to); err != nil { panic(fmt.Errorf("failed to put deposit for %s into the storage: %w", from.StringBE(), err)) } return stackitem.Null{} } // lockDepositUntil updates the chain's height until which deposit is locked. func (n *Notary) lockDepositUntil(ic *interop.Context, args []stackitem.Item) stackitem.Item { addr := toUint160(args[0]) ok, err := runtime.CheckHashedWitness(ic, addr) if err != nil { panic(fmt.Errorf("failed to check witness for %s: %w", addr.StringBE(), err)) } if !ok { return stackitem.NewBool(false) } till := toUint32(args[1]) if till < ic.Chain.BlockHeight() { return stackitem.NewBool(false) } deposit := n.GetDepositFor(ic.DAO, addr) if deposit == nil { return stackitem.NewBool(false) } if till < deposit.Till { return stackitem.NewBool(false) } deposit.Till = till err = n.putDepositFor(ic.DAO, deposit, addr) if err != nil { panic(fmt.Errorf("failed to put deposit for %s into the storage: %w", addr.StringBE(), err)) } return stackitem.NewBool(true) } // withdraw sends all deposited GAS for "from" address to "to" address. func (n *Notary) withdraw(ic *interop.Context, args []stackitem.Item) stackitem.Item { from := toUint160(args[0]) ok, err := runtime.CheckHashedWitness(ic, from) if err != nil { panic(fmt.Errorf("failed to check witness for %s: %w", from.StringBE(), err)) } if !ok { return stackitem.NewBool(false) } to := from if !args[1].Equals(stackitem.Null{}) { to = toUint160(args[1]) } deposit := n.GetDepositFor(ic.DAO, from) if deposit == nil { return stackitem.NewBool(false) } if ic.Chain.BlockHeight() < deposit.Till { return stackitem.NewBool(false) } cs, err := ic.GetContract(n.GAS.Hash) if err != nil { panic(fmt.Errorf("failed to get GAS contract state: %w", err)) } transferArgs := []stackitem.Item{stackitem.NewByteArray(n.Hash.BytesBE()), stackitem.NewByteArray(to.BytesBE()), stackitem.NewBigInteger(deposit.Amount), stackitem.Null{}} err = contract.CallFromNative(ic, n.Hash, cs, "transfer", transferArgs, vm.EnsureNotEmpty) if err != nil { panic(fmt.Errorf("failed to transfer GAS from Notary account: %w", err)) } if !ic.VM.Estack().Pop().Bool() { panic("failed to transfer GAS from Notary account: `transfer` returned false") } if err := n.removeDepositFor(ic.DAO, from); err != nil { panic(fmt.Errorf("failed to remove withdrawn deposit for %s from the storage: %w", from.StringBE(), err)) } return stackitem.NewBool(true) } // balanceOf returns deposited GAS amount for specified address. func (n *Notary) balanceOf(ic *interop.Context, args []stackitem.Item) stackitem.Item { acc := toUint160(args[0]) return stackitem.NewBigInteger(n.BalanceOf(ic.DAO, acc)) } // BalanceOf is an internal representation of `balanceOf` Notary method. func (n *Notary) BalanceOf(dao dao.DAO, acc util.Uint160) *big.Int { deposit := n.GetDepositFor(dao, acc) if deposit == nil { return big.NewInt(0) } return deposit.Amount } // expirationOf Returns deposit lock height for specified address. func (n *Notary) expirationOf(ic *interop.Context, args []stackitem.Item) stackitem.Item { acc := toUint160(args[0]) return stackitem.Make(n.ExpirationOf(ic.DAO, acc)) } // ExpirationOf is an internal representation of `expirationOf` Notary method. func (n *Notary) ExpirationOf(dao dao.DAO, acc util.Uint160) uint32 { deposit := n.GetDepositFor(dao, acc) if deposit == nil { return 0 } return deposit.Till } // verify checks whether the transaction was signed by one of the notaries. func (n *Notary) verify(ic *interop.Context, args []stackitem.Item) stackitem.Item { sig, err := args[0].TryBytes() if err != nil { panic(fmt.Errorf("failed to get signature bytes: %w", err)) } tx := ic.Tx if len(tx.GetAttributes(transaction.NotaryAssistedT)) == 0 { return stackitem.NewBool(false) } for _, signer := range tx.Signers { if signer.Account == n.Hash { if signer.Scopes != transaction.None { return stackitem.NewBool(false) } } } if tx.Sender() == n.Hash { if len(tx.Signers) != 2 { return stackitem.NewBool(false) } payer := tx.Signers[1].Account balance := n.GetDepositFor(ic.DAO, payer) if balance == nil || balance.Amount.Cmp(big.NewInt(tx.NetworkFee+tx.SystemFee)) < 0 { return stackitem.NewBool(false) } } notaries, err := n.GetNotaryNodes(ic.DAO) if err != nil { panic(fmt.Errorf("failed to get notary nodes: %w", err)) } hash := tx.GetSignedHash().BytesBE() var verified bool for _, n := range notaries { if n.Verify(sig, hash) { verified = true break } } return stackitem.NewBool(verified) } // GetNotaryNodes returns public keys of notary nodes. func (n *Notary) GetNotaryNodes(d dao.DAO) (keys.PublicKeys, error) { nodes, _, err := n.Desig.GetDesignatedByRole(d, RoleP2PNotary, math.MaxUint32) return nodes, err } // getMaxNotValidBeforeDelta is Notary contract method and returns the maximum NotValidBefore delta. func (n *Notary) getMaxNotValidBeforeDelta(ic *interop.Context, _ []stackitem.Item) stackitem.Item { return stackitem.NewBigInteger(big.NewInt(int64(n.GetMaxNotValidBeforeDelta(ic.DAO)))) } // GetMaxNotValidBeforeDelta is an internal representation of Notary getMaxNotValidBeforeDelta method. func (n *Notary) GetMaxNotValidBeforeDelta(dao dao.DAO) uint32 { n.lock.RLock() defer n.lock.RUnlock() if n.isValid { return n.maxNotValidBeforeDelta } return getUint32WithKey(n.ContractID, dao, maxNotValidBeforeDeltaKey, defaultMaxNotValidBeforeDelta) } // setMaxNotValidBeforeDelta is Notary contract method and sets the maximum NotValidBefore delta. func (n *Notary) setMaxNotValidBeforeDelta(ic *interop.Context, args []stackitem.Item) stackitem.Item { value := toUint32(args[0]) if value > transaction.MaxValidUntilBlockIncrement/2 || value < uint32(ic.Chain.GetConfig().ValidatorsCount) { panic(fmt.Errorf("MaxNotValidBeforeDelta cannot be more than %d or less than %d", transaction.MaxValidUntilBlockIncrement/2, ic.Chain.GetConfig().ValidatorsCount)) } ok, err := checkValidators(ic) if err != nil { panic(fmt.Errorf("failed to check committee signature: %w", err)) } if !ok { return stackitem.NewBool(false) } n.lock.Lock() defer n.lock.Unlock() err = setUint32WithKey(n.ContractID, ic.DAO, maxNotValidBeforeDeltaKey, value) if err != nil { panic(fmt.Errorf("failed to put value into the storage: %w", err)) } n.isValid = false return stackitem.NewBool(true) } // GetDepositFor returns state.Deposit for the account specified. It returns nil in case if // deposit is not found in storage and panics in case of any other error. func (n *Notary) GetDepositFor(dao dao.DAO, acc util.Uint160) *state.Deposit { key := append([]byte{prefixDeposit}, acc.BytesBE()...) deposit := new(state.Deposit) err := getSerializableFromDAO(n.ContractID, dao, key, deposit) if err == nil { return deposit } if err == storage.ErrKeyNotFound { return nil } panic(fmt.Errorf("failed to get deposit for %s from storage: %w", acc.StringBE(), err)) } // putDepositFor puts deposit on the balance of the specified account in the storage. func (n *Notary) putDepositFor(dao dao.DAO, deposit *state.Deposit, acc util.Uint160) error { key := append([]byte{prefixDeposit}, acc.BytesBE()...) return putSerializableToDAO(n.ContractID, dao, key, deposit) } // removeDepositFor removes deposit from the storage. func (n *Notary) removeDepositFor(dao dao.DAO, acc util.Uint160) error { key := append([]byte{prefixDeposit}, acc.BytesBE()...) return dao.DeleteStorageItem(n.ContractID, key) } // calculateNotaryReward calculates the reward for a single notary node based on FEE's count and Notary nodes count. func calculateNotaryReward(nFees int64, notariesCount int) *big.Int { return big.NewInt(nFees * transaction.NotaryServiceFeePerKey / int64(notariesCount)) }