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

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package native
import (
"fmt"
"github.com/nspcc-dev/neo-go/pkg/core/interop"
"github.com/nspcc-dev/neo-go/pkg/io"
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"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"
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"github.com/pkg/errors"
)
// Contracts is a set of registered native contracts.
type Contracts struct {
NEO *NEO
GAS *GAS
Policy *Policy
Contracts []interop.Contract
// persistScript is vm script which executes "onPersist" method of every native contract.
persistScript []byte
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}
// ByHash returns native contract with the specified hash.
func (cs *Contracts) ByHash(h util.Uint160) interop.Contract {
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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) interop.Contract {
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for _, ctr := range cs.Contracts {
if ctr.Metadata().ServiceID == id {
return ctr
}
}
return nil
}
// NewContracts returns new set of native contracts with new GAS, NEO and Policy
// contracts.
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func NewContracts() *Contracts {
cs := new(Contracts)
gas := NewGAS()
neo := NewNEO()
neo.GAS = gas
gas.NEO = neo
cs.GAS = gas
cs.Contracts = append(cs.Contracts, gas)
cs.NEO = neo
cs.Contracts = append(cs.Contracts, neo)
policy := newPolicy()
cs.Policy = policy
cs.Contracts = append(cs.Contracts, policy)
return cs
}
// GetPersistScript returns VM script calling "onPersist" method of every native contract.
func (cs *Contracts) GetPersistScript() []byte {
if cs.persistScript != nil {
return cs.persistScript
}
w := io.NewBufBinWriter()
for i := range cs.Contracts {
md := cs.Contracts[i].Metadata()
emit.Int(w.BinWriter, 0)
emit.Opcode(w.BinWriter, opcode.NEWARRAY)
emit.String(w.BinWriter, "onPersist")
emit.AppCall(w.BinWriter, md.Hash)
}
cs.persistScript = w.Bytes()
return cs.persistScript
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}
// 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),
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}
}
return nil
}
}
// getNativeInterop returns native contract interop.
func getNativeInterop(ic *interop.Context, c interop.Contract) func(v *vm.VM) error {
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return func(v *vm.VM) error {
h := v.GetCurrentScriptHash()
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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)
}
if !v.Context().GetCallFlags().Has(m.RequiredFlags) {
return errors.New("missing call flags")
}
if !v.AddGas(m.Price) {
return errors.New("gas limit exceeded")
}
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result := m.Func(ic, args)
v.Estack().PushVal(result)
return nil
}
}