neo-go/pkg/core/interop_system.go

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package core
import (
"crypto/elliptic"
"errors"
"fmt"
"math"
"math/big"
"github.com/nspcc-dev/neo-go/pkg/core/block"
"github.com/nspcc-dev/neo-go/pkg/core/blockchainer"
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"github.com/nspcc-dev/neo-go/pkg/core/dao"
"github.com/nspcc-dev/neo-go/pkg/core/interop"
"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/keys"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/vm"
"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
)
const (
// MaxStorageKeyLen is the maximum length of a key for storage items.
MaxStorageKeyLen = 64
// MaxStorageValueLen is the maximum length of a value for storage items.
// It is set to be the maximum value for uint16.
MaxStorageValueLen = 65535
)
// StorageContext contains storing id and read/write flag, it's used as
// a context for storage manipulation functions.
type StorageContext struct {
ID int32
ReadOnly bool
}
// StorageFlag represents storage flag which denotes whether the stored value is
// a constant.
type StorageFlag byte
const (
// None is a storage flag for non-constant items.
None StorageFlag = 0
// Constant is a storage flag for constant items.
Constant StorageFlag = 0x01
)
// getBlockHashFromElement converts given vm.Element to block hash using given
// Blockchainer if needed. Interop functions accept both block numbers and
// block hashes as parameters, thus this function is needed.
func getBlockHashFromElement(bc blockchainer.Blockchainer, element *vm.Element) (util.Uint256, error) {
var hash util.Uint256
hashbytes := element.Bytes()
if len(hashbytes) <= 5 {
hashint := element.BigInt().Int64()
if hashint < 0 || hashint > math.MaxUint32 {
return hash, errors.New("bad block index")
}
hash = bc.GetHeaderHash(int(hashint))
} else {
return util.Uint256DecodeBytesBE(hashbytes)
}
return hash, nil
}
// blockToStackItem converts block.Block to stackitem.Item
func blockToStackItem(b *block.Block) stackitem.Item {
return stackitem.NewArray([]stackitem.Item{
stackitem.NewByteArray(b.Hash().BytesBE()),
stackitem.NewBigInteger(big.NewInt(int64(b.Version))),
stackitem.NewByteArray(b.PrevHash.BytesBE()),
stackitem.NewByteArray(b.MerkleRoot.BytesBE()),
stackitem.NewBigInteger(big.NewInt(int64(b.Timestamp))),
stackitem.NewBigInteger(big.NewInt(int64(b.Index))),
stackitem.NewByteArray(b.NextConsensus.BytesBE()),
stackitem.NewBigInteger(big.NewInt(int64(len(b.Transactions)))),
})
}
// bcGetBlock returns current block.
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func bcGetBlock(ic *interop.Context) error {
hash, err := getBlockHashFromElement(ic.Chain, ic.VM.Estack().Pop())
if err != nil {
return err
}
block, err := ic.Chain.GetBlock(hash)
if err != nil || !isTraceableBlock(ic, block.Index) {
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ic.VM.Estack().PushVal(stackitem.Null{})
} else {
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ic.VM.Estack().PushVal(blockToStackItem(block))
}
return nil
}
// bcGetHeight returns blockchain height.
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func bcGetHeight(ic *interop.Context) error {
ic.VM.Estack().PushVal(ic.Chain.BlockHeight())
return nil
}
// getTransactionAndHeight gets parameter from the vm evaluation stack and
// returns transaction and its height if it's present in the blockchain.
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func getTransactionAndHeight(cd *dao.Cached, v *vm.VM) (*transaction.Transaction, uint32, error) {
hashbytes := v.Estack().Pop().Bytes()
hash, err := util.Uint256DecodeBytesBE(hashbytes)
if err != nil {
return nil, 0, err
}
return cd.GetTransaction(hash)
}
// isTraceableBlock defines whether we're able to give information about
// the block with index specified.
func isTraceableBlock(ic *interop.Context, index uint32) bool {
height := ic.Chain.BlockHeight()
MaxTraceableBlocks := ic.Chain.GetConfig().MaxTraceableBlocks
return index <= height && index+MaxTraceableBlocks > height
}
// transactionToStackItem converts transaction.Transaction to stackitem.Item
func transactionToStackItem(t *transaction.Transaction) stackitem.Item {
return stackitem.NewArray([]stackitem.Item{
stackitem.NewByteArray(t.Hash().BytesBE()),
stackitem.NewBigInteger(big.NewInt(int64(t.Version))),
stackitem.NewBigInteger(big.NewInt(int64(t.Nonce))),
stackitem.NewByteArray(t.Sender().BytesBE()),
stackitem.NewBigInteger(big.NewInt(int64(t.SystemFee))),
stackitem.NewBigInteger(big.NewInt(int64(t.NetworkFee))),
stackitem.NewBigInteger(big.NewInt(int64(t.ValidUntilBlock))),
stackitem.NewByteArray(t.Script),
})
}
// bcGetTransaction returns transaction.
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func bcGetTransaction(ic *interop.Context) error {
tx, h, err := getTransactionAndHeight(ic.DAO, ic.VM)
if err != nil || !isTraceableBlock(ic, h) {
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ic.VM.Estack().PushVal(stackitem.Null{})
return nil
}
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ic.VM.Estack().PushVal(transactionToStackItem(tx))
return nil
}
// bcGetTransactionFromBlock returns transaction with the given index from the
// block with height or hash specified.
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func bcGetTransactionFromBlock(ic *interop.Context) error {
hash, err := getBlockHashFromElement(ic.Chain, ic.VM.Estack().Pop())
if err != nil {
return err
}
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index := ic.VM.Estack().Pop().BigInt().Int64()
block, err := ic.DAO.GetBlock(hash)
if err != nil || !isTraceableBlock(ic, block.Index) {
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ic.VM.Estack().PushVal(stackitem.Null{})
return nil
}
if index < 0 || index >= int64(len(block.Transactions)) {
return errors.New("wrong transaction index")
}
tx := block.Transactions[index]
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ic.VM.Estack().PushVal(tx.Hash().BytesBE())
return nil
}
// bcGetTransactionHeight returns transaction height.
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func bcGetTransactionHeight(ic *interop.Context) error {
_, h, err := getTransactionAndHeight(ic.DAO, ic.VM)
if err != nil || !isTraceableBlock(ic, h) {
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ic.VM.Estack().PushVal(-1)
return nil
}
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ic.VM.Estack().PushVal(h)
return nil
}
// engineGetScriptContainer returns transaction or block that contains the script
// being run.
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func engineGetScriptContainer(ic *interop.Context) error {
var item stackitem.Item
switch t := ic.Container.(type) {
case *transaction.Transaction:
item = transactionToStackItem(t)
case *block.Block:
item = blockToStackItem(t)
default:
return errors.New("unknown script container")
}
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ic.VM.Estack().PushVal(item)
return nil
}
// storageDelete deletes stored key-value pair.
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func storageDelete(ic *interop.Context) error {
stcInterface := ic.VM.Estack().Pop().Value()
stc, ok := stcInterface.(*StorageContext)
if !ok {
return fmt.Errorf("%T is not a StorageContext", stcInterface)
}
if stc.ReadOnly {
return errors.New("StorageContext is read only")
}
ic.VM.AddGas(ic.Chain.GetPolicer().GetStoragePrice())
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key := ic.VM.Estack().Pop().Bytes()
si := ic.DAO.GetStorageItem(stc.ID, key)
if si != nil && si.IsConst {
return errors.New("storage item is constant")
}
return ic.DAO.DeleteStorageItem(stc.ID, key)
}
// storageGet returns stored key-value pair.
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func storageGet(ic *interop.Context) error {
stcInterface := ic.VM.Estack().Pop().Value()
stc, ok := stcInterface.(*StorageContext)
if !ok {
return fmt.Errorf("%T is not a StorageContext", stcInterface)
}
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key := ic.VM.Estack().Pop().Bytes()
si := ic.DAO.GetStorageItem(stc.ID, key)
if si != nil && si.Value != nil {
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ic.VM.Estack().PushVal(si.Value)
} else {
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ic.VM.Estack().PushVal(stackitem.Null{})
}
return nil
}
// storageGetContext returns storage context (scripthash).
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func storageGetContext(ic *interop.Context) error {
return storageGetContextInternal(ic, false)
}
// storageGetReadOnlyContext returns read-only context (scripthash).
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func storageGetReadOnlyContext(ic *interop.Context) error {
return storageGetContextInternal(ic, true)
}
// storageGetContextInternal is internal version of storageGetContext and
// storageGetReadOnlyContext which allows to specify ReadOnly context flag.
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func storageGetContextInternal(ic *interop.Context, isReadOnly bool) error {
contract, err := ic.GetContract(ic.VM.GetCurrentScriptHash())
if err != nil {
return err
}
sc := &StorageContext{
ID: contract.ID,
ReadOnly: isReadOnly,
}
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ic.VM.Estack().PushVal(stackitem.NewInterop(sc))
return nil
}
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func putWithContextAndFlags(ic *interop.Context, stc *StorageContext, key []byte, value []byte, isConst bool) error {
if len(key) > MaxStorageKeyLen {
return errors.New("key is too big")
}
if len(value) > MaxStorageValueLen {
return errors.New("value is too big")
}
if stc.ReadOnly {
return errors.New("StorageContext is read only")
}
si := ic.DAO.GetStorageItem(stc.ID, key)
if si != nil && si.IsConst {
return errors.New("storage item exists and is read-only")
}
sizeInc := 1
if si == nil {
si = &state.StorageItem{}
sizeInc = len(key) + len(value)
} else if len(value) != 0 {
if len(value) <= len(si.Value) {
sizeInc = (len(value)-1)/4 + 1
} else {
sizeInc = (len(si.Value)-1)/4 + 1 + len(value) - len(si.Value)
}
}
if !ic.VM.AddGas(int64(sizeInc) * ic.Chain.GetPolicer().GetStoragePrice()) {
return errGasLimitExceeded
}
si.Value = value
si.IsConst = isConst
return ic.DAO.PutStorageItem(stc.ID, key, si)
}
// storagePutInternal is a unified implementation of storagePut and storagePutEx.
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func storagePutInternal(ic *interop.Context, getFlag bool) error {
stcInterface := ic.VM.Estack().Pop().Value()
stc, ok := stcInterface.(*StorageContext)
if !ok {
return fmt.Errorf("%T is not a StorageContext", stcInterface)
}
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key := ic.VM.Estack().Pop().Bytes()
value := ic.VM.Estack().Pop().Bytes()
var flag int
if getFlag {
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flag = int(ic.VM.Estack().Pop().BigInt().Int64())
}
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return putWithContextAndFlags(ic, stc, key, value, int(Constant)&flag != 0)
}
// storagePut puts key-value pair into the storage.
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func storagePut(ic *interop.Context) error {
return storagePutInternal(ic, false)
}
// storagePutEx puts key-value pair with given flags into the storage.
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func storagePutEx(ic *interop.Context) error {
return storagePutInternal(ic, true)
}
// storageContextAsReadOnly sets given context to read-only mode.
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func storageContextAsReadOnly(ic *interop.Context) error {
stcInterface := ic.VM.Estack().Pop().Value()
stc, ok := stcInterface.(*StorageContext)
if !ok {
return fmt.Errorf("%T is not a StorageContext", stcInterface)
}
if !stc.ReadOnly {
stx := &StorageContext{
ID: stc.ID,
ReadOnly: true,
}
stc = stx
}
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ic.VM.Estack().PushVal(stackitem.NewInterop(stc))
return nil
}
// contractIsStandard checks if contract is standard (sig or multisig) contract.
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func contractIsStandard(ic *interop.Context) error {
h := ic.VM.Estack().Pop().Bytes()
u, err := util.Uint160DecodeBytesBE(h)
if err != nil {
return err
}
var result bool
cs, _ := ic.GetContract(u)
if cs != nil {
result = vm.IsStandardContract(cs.Script)
} else {
if tx, ok := ic.Container.(*transaction.Transaction); ok {
for _, witness := range tx.Scripts {
if witness.ScriptHash() == u {
result = vm.IsStandardContract(witness.VerificationScript)
break
}
}
}
}
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ic.VM.Estack().PushVal(result)
return nil
}
// contractCreateStandardAccount calculates contract scripthash for a given public key.
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func contractCreateStandardAccount(ic *interop.Context) error {
h := ic.VM.Estack().Pop().Bytes()
p, err := keys.NewPublicKeyFromBytes(h, elliptic.P256())
if err != nil {
return err
}
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ic.VM.Estack().PushVal(p.GetScriptHash().BytesBE())
return nil
}
// contractGetCallFlags returns current context calling flags.
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func contractGetCallFlags(ic *interop.Context) error {
ic.VM.Estack().PushVal(ic.VM.Context().GetCallFlags())
return nil
}