neoneo-go/pkg/core/native/contract.go

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2020-03-19 15:52:37 +00:00
package native
import (
"fmt"
"github.com/nspcc-dev/neo-go/pkg/core/interop"
"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"
"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/emit"
"github.com/pkg/errors"
)
// Method is a signature for a native method.
type Method = func(ic *interop.Context, args []vm.StackItem) vm.StackItem
// MethodAndPrice is a native-contract method descriptor.
type MethodAndPrice struct {
Func Method
Price int64
RequiredFlags smartcontract.CallFlag
}
// Contract is an interface for all native contracts.
type Contract interface {
Metadata() *ContractMD
OnPersist(*interop.Context) error
}
// ContractMD represents native contract instance.
type ContractMD struct {
Manifest manifest.Manifest
ServiceName string
ServiceID uint32
Script []byte
Hash util.Uint160
Methods map[string]MethodAndPrice
}
// Contracts is a set of registered native contracts.
type Contracts struct {
Contracts []Contract
}
// NewContractMD returns Contract with the specified list of methods.
func NewContractMD(name string) *ContractMD {
c := &ContractMD{
ServiceName: name,
ServiceID: vm.InteropNameToID([]byte(name)),
Methods: make(map[string]MethodAndPrice),
}
w := io.NewBufBinWriter()
emit.Syscall(w.BinWriter, c.ServiceName)
c.Script = w.Bytes()
c.Hash = hash.Hash160(c.Script)
c.Manifest = *manifest.DefaultManifest(c.Hash)
return c
}
// ByHash returns native contract with the specified hash.
func (cs *Contracts) ByHash(h util.Uint160) Contract {
for _, ctr := range cs.Contracts {
if ctr.Metadata().Hash.Equals(h) {
return ctr
}
}
return nil
}
// ByID returns native contract with the specified id.
func (cs *Contracts) ByID(id uint32) Contract {
for _, ctr := range cs.Contracts {
if ctr.Metadata().ServiceID == id {
return ctr
}
}
return nil
}
// AddMethod adds new method to a native contract.
func (c *ContractMD) AddMethod(md *MethodAndPrice, desc *manifest.Method, safe bool) {
c.Manifest.ABI.Methods = append(c.Manifest.ABI.Methods, *desc)
c.Methods[desc.Name] = *md
if safe {
c.Manifest.SafeMethods.Add(desc.Name)
}
}
// 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,
})
}
// NewContracts returns new empty set of native contracts.
func NewContracts() *Contracts {
return &Contracts{
Contracts: []Contract{},
}
}
// Add adds new native contracts to the list.
func (cs *Contracts) Add(c Contract) {
cs.Contracts = append(cs.Contracts, c)
}
// GetNativeInterop returns an interop getter for a given set of contracts.
func (cs *Contracts) GetNativeInterop(ic *interop.Context) func(uint32) *vm.InteropFuncPrice {
return func(id uint32) *vm.InteropFuncPrice {
if c := cs.ByID(id); c != nil {
return &vm.InteropFuncPrice{
Func: getNativeInterop(ic, c),
Price: 0, // TODO price func
}
}
return nil
}
}
// getNativeInterop returns native contract interop.
func getNativeInterop(ic *interop.Context, c Contract) func(v *vm.VM) error {
return func(v *vm.VM) error {
h := v.GetContextScriptHash(0)
if !h.Equals(c.Metadata().Hash) {
return errors.New("invalid hash")
}
name := string(v.Estack().Pop().Bytes())
args := v.Estack().Pop().Array()
m, ok := c.Metadata().Methods[name]
if !ok {
return fmt.Errorf("method %s not found", name)
}
result := m.Func(ic, args)
v.Estack().PushVal(result)
return nil
}
}