neo-go/pkg/core/interop/context.go

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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/storage"
"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 the 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
Hardforks map[string]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
loadToken func(ic *Context, id int32) error
GetRandomCounter uint32
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,
loadTokenFunc func(ic *Context, id int32) error,
block *block.Block, tx *transaction.Transaction, log *zap.Logger) *Context {
dao := d.GetPrivate()
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cfg := bc.GetConfig()
return &Context{
Chain: bc,
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Network: uint32(cfg.Magic),
Hardforks: cfg.Hardforks,
Natives: natives,
Trigger: trigger,
Block: block,
Tx: tx,
DAO: dao,
Log: log,
Invocations: make(map[util.Uint160]int),
getContract: getContract,
baseExecFee: baseExecFee,
baseStorageFee: baseStorageFee,
loadToken: loadTokenFunc,
}
}
// 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 the 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 the 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
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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
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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 a 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 the contract state and affects state dump.
// Therefore, values are taken from C# node.
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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 a 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 a 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
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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
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}
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 method 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 the 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 a new event to the 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 if the contract was deployed by the specified height.
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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 a contract by its hash in the 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
}
// LoadToken wraps externally provided load-token loading function providing it with context,
// this function can then be easily used by VM.
func (ic *Context) LoadToken(id int32) error {
return ic.loadToken(ic, id)
}
// SyscallHandler handles syscall with id.
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func (ic *Context) SyscallHandler(_ *vm.VM, id uint32) error {
f := ic.GetFunction(id)
if f == nil {
return errors.New("syscall not found")
}
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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")
}
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return f.Func(ic)
}
// SpawnVM spawns a new VM with the specified gas limit and set context.VM field.
func (ic *Context) SpawnVM() *vm.VM {
v := vm.NewWithTrigger(ic.Trigger)
ic.initVM(v)
return v
}
func (ic *Context) initVM(v *vm.VM) {
v.LoadToken = ic.LoadToken
v.GasLimit = -1
v.SyscallHandler = ic.SyscallHandler
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v.SetPriceGetter(ic.GetPrice)
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ic.VM = v
}
// ReuseVM resets given VM and allows to reuse it in the current context.
func (ic *Context) ReuseVM(v *vm.VM) {
v.Reset(ic.Trigger)
ic.initVM(v)
}
// RegisterCancelFunc adds the given function to the list of functions to be called after the 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()
}
// BlockHeight returns current block height got from Context's block if it's set.
func (ic *Context) BlockHeight() uint32 {
if ic.Block != nil {
return ic.Block.Index - 1 // Persisting block is not yet stored.
}
return ic.Chain.BlockHeight()
}
// CurrentBlockHash returns current block hash got from Context's block if it's set.
func (ic *Context) CurrentBlockHash() util.Uint256 {
if ic.Block != nil {
return ic.Chain.GetHeaderHash(int(ic.Block.Index - 1)) // Persisting block is not yet stored.
}
return ic.Chain.CurrentBlockHash()
}
// GetBlock returns block if it exists and available at the current Context's height.
func (ic *Context) GetBlock(hash util.Uint256) (*block.Block, error) {
block, err := ic.Chain.GetBlock(hash)
if err != nil {
return nil, err
}
if block.Index > ic.BlockHeight() {
return nil, storage.ErrKeyNotFound
}
return block, nil
}
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// IsHardforkEnabled tells whether specified hard-fork enabled at the current context height.
func (ic *Context) IsHardforkEnabled(hf config.Hardfork) bool {
height, ok := ic.Hardforks[hf.String()]
if ok {
return ic.BlockHeight() >= height
}
return len(ic.Hardforks) == 0 // Enable each hard-fork by default.
}
// AddNotification creates notification event and appends it to the notification list.
func (ic *Context) AddNotification(hash util.Uint160, name string, item *stackitem.Array) {
ic.Notifications = append(ic.Notifications, state.NotificationEvent{
ScriptHash: hash,
Name: name,
Item: item,
})
}