package native import ( "encoding/binary" "fmt" "math/big" "sort" "sync" "github.com/nspcc-dev/neo-go/pkg/core/block" "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/runtime" "github.com/nspcc-dev/neo-go/pkg/core/state" "github.com/nspcc-dev/neo-go/pkg/core/transaction" "github.com/nspcc-dev/neo-go/pkg/network/payload" "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/stackitem" ) const ( policyName = "Policy" policyContractID = -3 defaultMaxBlockSize = 1024 * 256 defaultMaxTransactionsPerBlock = 512 defaultFeePerByte = 1000 defaultMaxVerificationGas = 50000000 defaultMaxBlockSystemFee = 9000 * GASFactor // minBlockSystemFee is the minimum allowed system fee per block. minBlockSystemFee = 4007600 // maxFeePerByte is the maximum allowed fee per byte value. maxFeePerByte = 100_000_000 // blockedAccountPrefix is a prefix used to store blocked account. blockedAccountPrefix = 15 ) var ( // maxTransactionsPerBlockKey is a key used to store the maximum number of // transactions allowed in block. maxTransactionsPerBlockKey = []byte{23} // feePerByteKey is a key used to store the minimum fee per byte for // transaction. feePerByteKey = []byte{10} // maxBlockSizeKey is a key used to store the maximum block size value. maxBlockSizeKey = []byte{12} // maxBlockSystemFeeKey is a key used to store the maximum block system fee value. maxBlockSystemFeeKey = []byte{17} ) // Policy represents Policy native contract. type Policy struct { interop.ContractMD 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 maxTransactionsPerBlock uint32 maxBlockSize uint32 feePerByte int64 maxBlockSystemFee int64 maxVerificationGas int64 blockedAccounts []util.Uint160 } var _ interop.Contract = (*Policy)(nil) // newPolicy returns Policy native contract. func newPolicy() *Policy { p := &Policy{ContractMD: *interop.NewContractMD(policyName)} p.ContractID = policyContractID desc := newDescriptor("getMaxTransactionsPerBlock", smartcontract.IntegerType) md := newMethodAndPrice(p.getMaxTransactionsPerBlock, 1000000, smartcontract.AllowStates) p.AddMethod(md, desc, true) desc = newDescriptor("getMaxBlockSize", smartcontract.IntegerType) md = newMethodAndPrice(p.getMaxBlockSize, 1000000, smartcontract.AllowStates) p.AddMethod(md, desc, true) desc = newDescriptor("getFeePerByte", smartcontract.IntegerType) md = newMethodAndPrice(p.getFeePerByte, 1000000, smartcontract.AllowStates) p.AddMethod(md, desc, true) desc = newDescriptor("isBlocked", smartcontract.BoolType, manifest.NewParameter("account", smartcontract.Hash160Type)) md = newMethodAndPrice(p.isBlocked, 1000000, smartcontract.AllowStates) p.AddMethod(md, desc, true) desc = newDescriptor("getMaxBlockSystemFee", smartcontract.IntegerType) md = newMethodAndPrice(p.getMaxBlockSystemFee, 1000000, smartcontract.AllowStates) p.AddMethod(md, desc, true) desc = newDescriptor("setMaxBlockSize", smartcontract.BoolType, manifest.NewParameter("value", smartcontract.IntegerType)) md = newMethodAndPrice(p.setMaxBlockSize, 3000000, smartcontract.AllowModifyStates) p.AddMethod(md, desc, false) desc = newDescriptor("setMaxTransactionsPerBlock", smartcontract.BoolType, manifest.NewParameter("value", smartcontract.IntegerType)) md = newMethodAndPrice(p.setMaxTransactionsPerBlock, 3000000, smartcontract.AllowModifyStates) p.AddMethod(md, desc, false) desc = newDescriptor("setFeePerByte", smartcontract.BoolType, manifest.NewParameter("value", smartcontract.IntegerType)) md = newMethodAndPrice(p.setFeePerByte, 3000000, smartcontract.AllowModifyStates) p.AddMethod(md, desc, false) desc = newDescriptor("setMaxBlockSystemFee", smartcontract.BoolType, manifest.NewParameter("value", smartcontract.IntegerType)) md = newMethodAndPrice(p.setMaxBlockSystemFee, 3000000, smartcontract.AllowModifyStates) p.AddMethod(md, desc, false) desc = newDescriptor("blockAccount", smartcontract.BoolType, manifest.NewParameter("account", smartcontract.Hash160Type)) md = newMethodAndPrice(p.blockAccount, 3000000, smartcontract.AllowModifyStates) p.AddMethod(md, desc, false) desc = newDescriptor("unblockAccount", smartcontract.BoolType, manifest.NewParameter("account", smartcontract.Hash160Type)) md = newMethodAndPrice(p.unblockAccount, 3000000, smartcontract.AllowModifyStates) p.AddMethod(md, desc, false) desc = newDescriptor("name", smartcontract.StringType) md = newMethodAndPrice(nameMethod(policyName), 0, smartcontract.NoneFlag) p.AddMethod(md, desc, true) desc = newDescriptor("onPersist", smartcontract.VoidType) md = newMethodAndPrice(getOnPersistWrapper(p.OnPersist), 0, smartcontract.AllowModifyStates) p.AddMethod(md, desc, false) desc = newDescriptor("postPersist", smartcontract.VoidType) md = newMethodAndPrice(getOnPersistWrapper(postPersistBase), 0, smartcontract.AllowModifyStates) p.AddMethod(md, desc, false) return p } // Metadata implements Contract interface. func (p *Policy) Metadata() *interop.ContractMD { return &p.ContractMD } // Initialize initializes Policy native contract and implements Contract interface. func (p *Policy) Initialize(ic *interop.Context) error { p.isValid = true p.maxTransactionsPerBlock = defaultMaxTransactionsPerBlock p.maxBlockSize = defaultMaxBlockSize p.feePerByte = defaultFeePerByte p.maxBlockSystemFee = defaultMaxBlockSystemFee p.maxVerificationGas = defaultMaxVerificationGas p.blockedAccounts = make([]util.Uint160, 0) return nil } // OnPersist implements Contract interface. func (p *Policy) OnPersist(ic *interop.Context) error { return nil } // OnPersistEnd updates cached Policy values if they've been changed func (p *Policy) OnPersistEnd(dao dao.DAO) error { if p.isValid { return nil } p.lock.Lock() defer p.lock.Unlock() p.maxTransactionsPerBlock = p.getUint32WithKey(dao, maxTransactionsPerBlockKey, defaultMaxTransactionsPerBlock) p.maxBlockSize = p.getUint32WithKey(dao, maxBlockSizeKey, defaultMaxBlockSize) p.feePerByte = p.getInt64WithKey(dao, feePerByteKey, defaultFeePerByte) p.maxBlockSystemFee = p.getInt64WithKey(dao, maxBlockSystemFeeKey, defaultMaxBlockSystemFee) p.maxVerificationGas = defaultMaxVerificationGas p.blockedAccounts = make([]util.Uint160, 0) siMap, err := dao.GetStorageItemsWithPrefix(p.ContractID, []byte{blockedAccountPrefix}) if err != nil { return fmt.Errorf("failed to get blocked accounts from storage: %w", err) } for key := range siMap { hash, err := util.Uint160DecodeBytesBE([]byte(key)) if err != nil { return fmt.Errorf("failed to decode blocked account hash: %w", err) } p.blockedAccounts = append(p.blockedAccounts, hash) } sort.Slice(p.blockedAccounts, func(i, j int) bool { return p.blockedAccounts[i].Less(p.blockedAccounts[j]) }) p.isValid = true return nil } // getMaxTransactionsPerBlock is Policy contract method and returns the upper // limit of transactions per block. func (p *Policy) getMaxTransactionsPerBlock(ic *interop.Context, _ []stackitem.Item) stackitem.Item { return stackitem.NewBigInteger(big.NewInt(int64(p.GetMaxTransactionsPerBlockInternal(ic.DAO)))) } // GetMaxTransactionsPerBlockInternal returns the upper limit of transactions per // block. func (p *Policy) GetMaxTransactionsPerBlockInternal(dao dao.DAO) uint32 { p.lock.RLock() defer p.lock.RUnlock() if p.isValid { return p.maxTransactionsPerBlock } return p.getUint32WithKey(dao, maxTransactionsPerBlockKey, defaultMaxTransactionsPerBlock) } // getMaxBlockSize is Policy contract method and returns maximum block size. func (p *Policy) getMaxBlockSize(ic *interop.Context, _ []stackitem.Item) stackitem.Item { return stackitem.NewBigInteger(big.NewInt(int64(p.GetMaxBlockSizeInternal(ic.DAO)))) } // GetMaxBlockSizeInternal returns maximum block size. func (p *Policy) GetMaxBlockSizeInternal(dao dao.DAO) uint32 { p.lock.RLock() defer p.lock.RUnlock() if p.isValid { return p.maxBlockSize } return p.getUint32WithKey(dao, maxBlockSizeKey, defaultMaxBlockSize) } // getFeePerByte is Policy contract method and returns required transaction's fee // per byte. func (p *Policy) getFeePerByte(ic *interop.Context, _ []stackitem.Item) stackitem.Item { return stackitem.NewBigInteger(big.NewInt(p.GetFeePerByteInternal(ic.DAO))) } // GetFeePerByteInternal returns required transaction's fee per byte. func (p *Policy) GetFeePerByteInternal(dao dao.DAO) int64 { p.lock.RLock() defer p.lock.RUnlock() if p.isValid { return p.feePerByte } return p.getInt64WithKey(dao, feePerByteKey, defaultFeePerByte) } // GetMaxVerificationGas returns maximum gas allowed to be burned during verificaion. func (p *Policy) GetMaxVerificationGas(_ dao.DAO) int64 { if p.isValid { return p.maxVerificationGas } return defaultMaxVerificationGas } // getMaxBlockSystemFee is Policy contract method and returns the maximum overall // system fee per block. func (p *Policy) getMaxBlockSystemFee(ic *interop.Context, _ []stackitem.Item) stackitem.Item { return stackitem.NewBigInteger(big.NewInt(p.GetMaxBlockSystemFeeInternal(ic.DAO))) } // GetMaxBlockSystemFeeInternal the maximum overall system fee per block. func (p *Policy) GetMaxBlockSystemFeeInternal(dao dao.DAO) int64 { p.lock.RLock() defer p.lock.RUnlock() if p.isValid { return p.maxBlockSystemFee } return p.getInt64WithKey(dao, maxBlockSystemFeeKey, defaultMaxBlockSystemFee) } // isBlocked is Policy contract method and checks whether provided account is blocked. func (p *Policy) isBlocked(ic *interop.Context, args []stackitem.Item) stackitem.Item { hash := toUint160(args[0]) return stackitem.NewBool(p.IsBlockedInternal(ic.DAO, hash)) } // IsBlockedInternal checks whether provided account is blocked func (p *Policy) IsBlockedInternal(dao dao.DAO, hash util.Uint160) bool { p.lock.RLock() defer p.lock.RUnlock() if p.isValid { length := len(p.blockedAccounts) i := sort.Search(length, func(i int) bool { return !p.blockedAccounts[i].Less(hash) }) if length != 0 && i != length && p.blockedAccounts[i].Equals(hash) { return true } return false } key := append([]byte{blockedAccountPrefix}, hash.BytesBE()...) return dao.GetStorageItem(p.ContractID, key) != nil } // setMaxTransactionsPerBlock is Policy contract method and sets the upper limit // of transactions per block. func (p *Policy) setMaxTransactionsPerBlock(ic *interop.Context, args []stackitem.Item) stackitem.Item { value := uint32(toBigInt(args[0]).Int64()) if value > block.MaxTransactionsPerBlock { panic(fmt.Errorf("MaxTransactionsPerBlock cannot exceed the maximum allowed transactions per block = %d", block.MaxTransactionsPerBlock)) } ok, err := p.checkValidators(ic) if err != nil { panic(err) } if !ok { return stackitem.NewBool(false) } p.lock.Lock() defer p.lock.Unlock() err = p.setUint32WithKey(ic.DAO, maxTransactionsPerBlockKey, value) if err != nil { panic(err) } p.isValid = false return stackitem.NewBool(true) } // setMaxBlockSize is Policy contract method and sets maximum block size. func (p *Policy) setMaxBlockSize(ic *interop.Context, args []stackitem.Item) stackitem.Item { value := uint32(toBigInt(args[0]).Int64()) if value > payload.MaxSize { panic(fmt.Errorf("MaxBlockSize cannot be more than the maximum payload size = %d", payload.MaxSize)) } ok, err := p.checkValidators(ic) if err != nil { panic(err) } if !ok { return stackitem.NewBool(false) } p.lock.Lock() defer p.lock.Unlock() err = p.setUint32WithKey(ic.DAO, maxBlockSizeKey, value) if err != nil { panic(err) } p.isValid = false return stackitem.NewBool(true) } // setFeePerByte is Policy contract method and sets transaction's fee per byte. func (p *Policy) setFeePerByte(ic *interop.Context, args []stackitem.Item) stackitem.Item { value := toBigInt(args[0]).Int64() if value < 0 || value > maxFeePerByte { panic(fmt.Errorf("FeePerByte shouldn't be negative or greater than %d", maxFeePerByte)) } ok, err := p.checkValidators(ic) if err != nil { panic(err) } if !ok { return stackitem.NewBool(false) } p.lock.Lock() defer p.lock.Unlock() err = p.setInt64WithKey(ic.DAO, feePerByteKey, value) if err != nil { panic(err) } p.isValid = false return stackitem.NewBool(true) } // setMaxBlockSystemFee is Policy contract method and sets the maximum system fee per block. func (p *Policy) setMaxBlockSystemFee(ic *interop.Context, args []stackitem.Item) stackitem.Item { value := toBigInt(args[0]).Int64() if value <= minBlockSystemFee { panic(fmt.Errorf("MaxBlockSystemFee cannot be less then %d", minBlockSystemFee)) } ok, err := p.checkValidators(ic) if err != nil { panic(err) } if !ok { return stackitem.NewBool(false) } p.lock.Lock() defer p.lock.Unlock() err = p.setInt64WithKey(ic.DAO, maxBlockSystemFeeKey, value) if err != nil { panic(err) } p.isValid = false return stackitem.NewBool(true) } // blockAccount is Policy contract method and adds given account hash to the list // of blocked accounts. func (p *Policy) blockAccount(ic *interop.Context, args []stackitem.Item) stackitem.Item { ok, err := p.checkValidators(ic) if err != nil { panic(err) } if !ok { return stackitem.NewBool(false) } hash := toUint160(args[0]) if p.IsBlockedInternal(ic.DAO, hash) { return stackitem.NewBool(false) } key := append([]byte{blockedAccountPrefix}, hash.BytesBE()...) p.lock.Lock() defer p.lock.Unlock() err = ic.DAO.PutStorageItem(p.ContractID, key, &state.StorageItem{ Value: []byte{0x01}, }) if err != nil { panic(err) } p.isValid = false return stackitem.NewBool(true) } // unblockAccount is Policy contract method and removes given account hash from // the list of blocked accounts. func (p *Policy) unblockAccount(ic *interop.Context, args []stackitem.Item) stackitem.Item { ok, err := p.checkValidators(ic) if err != nil { panic(err) } if !ok { return stackitem.NewBool(false) } hash := toUint160(args[0]) if !p.IsBlockedInternal(ic.DAO, hash) { return stackitem.NewBool(false) } key := append([]byte{blockedAccountPrefix}, hash.BytesBE()...) p.lock.Lock() defer p.lock.Unlock() err = ic.DAO.DeleteStorageItem(p.ContractID, key) if err != nil { panic(err) } p.isValid = false return stackitem.NewBool(true) } func (p *Policy) getUint32WithKey(dao dao.DAO, key []byte, defaultValue uint32) uint32 { si := dao.GetStorageItem(p.ContractID, key) if si == nil { return defaultValue } return binary.LittleEndian.Uint32(si.Value) } func (p *Policy) setUint32WithKey(dao dao.DAO, key []byte, value uint32) error { si := &state.StorageItem{ Value: make([]byte, 4), } binary.LittleEndian.PutUint32(si.Value, value) return dao.PutStorageItem(p.ContractID, key, si) } func (p *Policy) getInt64WithKey(dao dao.DAO, key []byte, defaultValue int64) int64 { si := dao.GetStorageItem(p.ContractID, key) if si == nil { return defaultValue } return int64(binary.LittleEndian.Uint64(si.Value)) } func (p *Policy) setInt64WithKey(dao dao.DAO, key []byte, value int64) error { si := &state.StorageItem{ Value: make([]byte, 8), } binary.LittleEndian.PutUint64(si.Value, uint64(value)) return dao.PutStorageItem(p.ContractID, key, si) } func (p *Policy) checkValidators(ic *interop.Context) (bool, error) { prevBlock, err := ic.Chain.GetBlock(ic.Block.PrevHash) if err != nil { return false, err } return runtime.CheckHashedWitness(ic, prevBlock.NextConsensus) } // CheckPolicy checks whether transaction conforms to current policy restrictions // like not being signed by blocked account or not exceeding block-level system // fee limit. func (p *Policy) CheckPolicy(d dao.DAO, tx *transaction.Transaction) error { for _, signer := range tx.Signers { if p.IsBlockedInternal(d, signer.Account) { return fmt.Errorf("account %s is blocked", signer.Account.StringLE()) } } maxBlockSystemFee := p.GetMaxBlockSystemFeeInternal(d) if maxBlockSystemFee < tx.SystemFee { return fmt.Errorf("transaction's fee can't exceed maximum block system fee %d", maxBlockSystemFee) } return nil }