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

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package interop
import (
"errors"
"fmt"
"sort"
"strings"
"github.com/nspcc-dev/neo-go/pkg/core/block"
"github.com/nspcc-dev/neo-go/pkg/core/blockchainer"
"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
)
// Context represents context in which interops are executed.
type Context struct {
Chain blockchainer.Blockchainer
Container hash.Hashable
Network uint32
Natives []Contract
Trigger trigger.Type
Block *block.Block
Tx *transaction.Transaction
DAO *dao.Cached
Notifications []state.NotificationEvent
Log *zap.Logger
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VM *vm.VM
Functions [][]Function
getContract func(dao.DAO, util.Uint160) (*state.Contract, error)
}
// NewContext returns new interop context.
func NewContext(trigger trigger.Type, bc blockchainer.Blockchainer, d dao.DAO,
getContract func(dao.DAO, util.Uint160) (*state.Contract, error), natives []Contract,
block *block.Block, tx *transaction.Transaction, log *zap.Logger) *Context {
dao := dao.NewCached(d)
nes := make([]state.NotificationEvent, 0)
return &Context{
Chain: bc,
Network: uint32(bc.GetConfig().Magic),
Natives: natives,
Trigger: trigger,
Block: block,
Tx: tx,
DAO: dao,
Notifications: nes,
Log: log,
// Functions is a slice of slices of interops sorted by ID.
Functions: [][]Function{},
getContract: getContract,
}
}
// 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
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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 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.
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c.NEF.Header.Compiler = "neo-core-v3.0"
c.NEF.Header.Magic = nef.Magic
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
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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
}
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,
})
}
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// 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 {
for _, slice := range ic.Functions {
n := sort.Search(len(slice), func(i int) bool {
return slice[i].ID >= id
})
if n < len(slice) && slice[n].ID == id {
return &slice[n]
}
}
return nil
}
// BaseExecFee represents factor to multiply syscall prices with.
func (ic *Context) BaseExecFee() int64 {
if ic.Chain == nil || (ic.Block != nil && ic.Block.Index == 0) {
return DefaultBaseExecFee
}
return ic.Chain.GetPolicer().GetBaseExecFee()
}
// 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)
}
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// 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
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ic.VM = v
return v
}