package interop import ( "context" "encoding/binary" "errors" "fmt" "sort" "strings" "github.com/nspcc-dev/neo-go/pkg/config" "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/interopnames" "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/crypto/hash" "github.com/nspcc-dev/neo-go/pkg/io" "github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag" "github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest" "github.com/nspcc-dev/neo-go/pkg/smartcontract/nef" "github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger" "github.com/nspcc-dev/neo-go/pkg/util" "github.com/nspcc-dev/neo-go/pkg/vm" "github.com/nspcc-dev/neo-go/pkg/vm/emit" "github.com/nspcc-dev/neo-go/pkg/vm/opcode" "github.com/nspcc-dev/neo-go/pkg/vm/stackitem" "go.uber.org/zap" ) const ( // DefaultBaseExecFee specifies default multiplier for opcode and syscall prices. DefaultBaseExecFee = 30 ) // Ledger is the interface to Blockchain required for Context functionality. type Ledger interface { BlockHeight() uint32 CurrentBlockHash() util.Uint256 GetBlock(hash util.Uint256) (*block.Block, error) GetConfig() config.ProtocolConfiguration GetHeaderHash(int) util.Uint256 } // Context represents context in which interops are executed. type Context struct { Chain Ledger Container hash.Hashable Network uint32 Natives []Contract Trigger trigger.Type Block *block.Block NonceData [16]byte Tx *transaction.Transaction DAO *dao.Simple Notifications []state.NotificationEvent Log *zap.Logger VM *vm.VM Functions []Function Invocations map[util.Uint160]int cancelFuncs []context.CancelFunc getContract func(*dao.Simple, util.Uint160) (*state.Contract, error) baseExecFee int64 baseStorageFee int64 signers []transaction.Signer } // NewContext returns new interop context. func NewContext(trigger trigger.Type, bc Ledger, d *dao.Simple, baseExecFee, baseStorageFee int64, getContract func(*dao.Simple, util.Uint160) (*state.Contract, error), natives []Contract, block *block.Block, tx *transaction.Transaction, log *zap.Logger) *Context { dao := d.GetPrivate() return &Context{ Chain: bc, Network: uint32(bc.GetConfig().Magic), Natives: natives, Trigger: trigger, Block: block, Tx: tx, DAO: dao, Log: log, Invocations: make(map[util.Uint160]int), getContract: getContract, baseExecFee: baseExecFee, baseStorageFee: baseStorageFee, } } // InitNonceData initializes nonce to be used in `GetRandom` calculations. func (ic *Context) InitNonceData() { if tx, ok := ic.Container.(*transaction.Transaction); ok { copy(ic.NonceData[:], tx.Hash().BytesBE()) } if ic.Block != nil { nonce := ic.Block.Nonce nonce ^= binary.LittleEndian.Uint64(ic.NonceData[:]) binary.LittleEndian.PutUint64(ic.NonceData[:], nonce) } } // UseSigners allows overriding signers used in this context. func (ic *Context) UseSigners(s []transaction.Signer) { ic.signers = s } // Signers returns signers witnessing current execution context. func (ic *Context) Signers() []transaction.Signer { if ic.signers != nil { return ic.signers } if ic.Tx != nil { return ic.Tx.Signers } return nil } // Function binds function name, id with the function itself and price, // it's supposed to be inited once for all interopContexts, so it doesn't use // vm.InteropFuncPrice directly. type Function struct { ID uint32 Name string Func func(*Context) error // ParamCount is a number of function parameters. ParamCount int Price int64 // RequiredFlags is a set of flags which must be set during script invocations. // Default value is NoneFlag i.e. no flags are required. RequiredFlags callflag.CallFlag } // Method is a signature for a native method. type Method = func(ic *Context, args []stackitem.Item) stackitem.Item // MethodAndPrice is a native-contract method descriptor. type MethodAndPrice struct { Func Method MD *manifest.Method CPUFee int64 StorageFee int64 SyscallOffset int RequiredFlags callflag.CallFlag } // Contract is an interface for all native contracts. type Contract interface { Initialize(*Context) error Metadata() *ContractMD OnPersist(*Context) error PostPersist(*Context) error } // ContractMD represents native contract instance. type ContractMD struct { state.NativeContract Name string Methods []MethodAndPrice } // NewContractMD returns Contract with the specified list of methods. func NewContractMD(name string, id int32) *ContractMD { c := &ContractMD{Name: name} c.ID = id // NEF is now stored in contract state and affects state dump. // Therefore values are taken from C# node. c.NEF.Header.Compiler = "neo-core-v3.0" c.NEF.Header.Magic = nef.Magic c.NEF.Tokens = []nef.MethodToken{} // avoid `nil` result during JSON marshalling c.Hash = state.CreateContractHash(util.Uint160{}, 0, c.Name) c.Manifest = *manifest.DefaultManifest(name) return c } // UpdateHash creates native contract script and updates hash. func (c *ContractMD) UpdateHash() { w := io.NewBufBinWriter() for i := range c.Methods { offset := w.Len() c.Methods[i].MD.Offset = offset c.Manifest.ABI.Methods[i].Offset = offset emit.Int(w.BinWriter, 0) c.Methods[i].SyscallOffset = w.Len() emit.Syscall(w.BinWriter, interopnames.SystemContractCallNative) emit.Opcodes(w.BinWriter, opcode.RET) } if w.Err != nil { panic(fmt.Errorf("can't create native contract script: %w", w.Err)) } c.NEF.Script = w.Bytes() c.NEF.Checksum = c.NEF.CalculateChecksum() } // AddMethod adds new method to a native contract. func (c *ContractMD) AddMethod(md *MethodAndPrice, desc *manifest.Method) { md.MD = desc desc.Safe = md.RequiredFlags&(callflag.All^callflag.ReadOnly) == 0 index := sort.Search(len(c.Manifest.ABI.Methods), func(i int) bool { md := c.Manifest.ABI.Methods[i] if md.Name != desc.Name { return md.Name >= desc.Name } return len(md.Parameters) > len(desc.Parameters) }) c.Manifest.ABI.Methods = append(c.Manifest.ABI.Methods, manifest.Method{}) copy(c.Manifest.ABI.Methods[index+1:], c.Manifest.ABI.Methods[index:]) c.Manifest.ABI.Methods[index] = *desc // Cache follows the same order. c.Methods = append(c.Methods, MethodAndPrice{}) copy(c.Methods[index+1:], c.Methods[index:]) c.Methods[index] = *md } // GetMethodByOffset returns with the provided offset. // Offset is offset of `System.Contract.CallNative` syscall. func (c *ContractMD) GetMethodByOffset(offset int) (MethodAndPrice, bool) { for k := range c.Methods { if c.Methods[k].SyscallOffset == offset { return c.Methods[k], true } } return MethodAndPrice{}, false } // GetMethod returns method `name` with specified number of parameters. func (c *ContractMD) GetMethod(name string, paramCount int) (MethodAndPrice, bool) { index := sort.Search(len(c.Methods), func(i int) bool { md := c.Methods[i] res := strings.Compare(name, md.MD.Name) switch res { case -1, 1: return res == -1 default: return paramCount <= len(md.MD.Parameters) } }) if index < len(c.Methods) { md := c.Methods[index] if md.MD.Name == name && (paramCount == -1 || len(md.MD.Parameters) == paramCount) { return md, true } } return MethodAndPrice{}, false } // AddEvent adds new event to a native contract. func (c *ContractMD) AddEvent(name string, ps ...manifest.Parameter) { c.Manifest.ABI.Events = append(c.Manifest.ABI.Events, manifest.Event{ Name: name, Parameters: ps, }) } // IsActive returns true iff the contract was deployed by the specified height. func (c *ContractMD) IsActive(height uint32) bool { history := c.UpdateHistory return len(history) != 0 && history[0] <= height } // Sort sorts interop functions by id. func Sort(fs []Function) { sort.Slice(fs, func(i, j int) bool { return fs[i].ID < fs[j].ID }) } // GetContract returns contract by its hash in current interop context. func (ic *Context) GetContract(hash util.Uint160) (*state.Contract, error) { return ic.getContract(ic.DAO, hash) } // GetFunction returns metadata for interop with the specified id. func (ic *Context) GetFunction(id uint32) *Function { n := sort.Search(len(ic.Functions), func(i int) bool { return ic.Functions[i].ID >= id }) if n < len(ic.Functions) && ic.Functions[n].ID == id { return &ic.Functions[n] } return nil } // BaseExecFee represents factor to multiply syscall prices with. func (ic *Context) BaseExecFee() int64 { return ic.baseExecFee } // BaseStorageFee represents price for storing one byte of data in the contract storage. func (ic *Context) BaseStorageFee() int64 { return ic.baseStorageFee } // SyscallHandler handles syscall with id. func (ic *Context) SyscallHandler(_ *vm.VM, id uint32) error { f := ic.GetFunction(id) if f == nil { return errors.New("syscall not found") } cf := ic.VM.Context().GetCallFlags() if !cf.Has(f.RequiredFlags) { return fmt.Errorf("missing call flags: %05b vs %05b", cf, f.RequiredFlags) } if !ic.VM.AddGas(f.Price * ic.BaseExecFee()) { return errors.New("insufficient amount of gas") } return f.Func(ic) } // SpawnVM spawns new VM with the specified gas limit and set context.VM field. func (ic *Context) SpawnVM() *vm.VM { v := vm.NewWithTrigger(ic.Trigger) v.GasLimit = -1 v.SyscallHandler = ic.SyscallHandler ic.VM = v return v } // RegisterCancelFunc adds given function to the list of functions to be called after VM // finishes script execution. func (ic *Context) RegisterCancelFunc(f context.CancelFunc) { if f != nil { ic.cancelFuncs = append(ic.cancelFuncs, f) } } // Finalize calls all registered cancel functions to release the occupied resources. func (ic *Context) Finalize() { for _, f := range ic.cancelFuncs { f() } ic.cancelFuncs = nil } // Exec executes loaded VM script and calls registered finalizers to release the occupied resources. func (ic *Context) Exec() error { defer ic.Finalize() return ic.VM.Run() }