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" "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. 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) { ic.VM.Estack().PushVal(stackitem.Null{}) } else { ic.VM.Estack().PushVal(blockToStackItem(block)) } return nil } // bcGetHeight returns blockchain height. 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. 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. func bcGetTransaction(ic *interop.Context) error { tx, h, err := getTransactionAndHeight(ic.DAO, ic.VM) if err != nil || !isTraceableBlock(ic, h) { ic.VM.Estack().PushVal(stackitem.Null{}) return nil } ic.VM.Estack().PushVal(transactionToStackItem(tx)) return nil } // bcGetTransactionFromBlock returns transaction with the given index from the // block with height or hash specified. func bcGetTransactionFromBlock(ic *interop.Context) error { hash, err := getBlockHashFromElement(ic.Chain, ic.VM.Estack().Pop()) if err != nil { return err } index := ic.VM.Estack().Pop().BigInt().Int64() block, err := ic.DAO.GetBlock(hash) if err != nil || !isTraceableBlock(ic, block.Index) { 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] ic.VM.Estack().PushVal(tx.Hash().BytesBE()) return nil } // bcGetTransactionHeight returns transaction height. func bcGetTransactionHeight(ic *interop.Context) error { _, h, err := getTransactionAndHeight(ic.DAO, ic.VM) if err != nil || !isTraceableBlock(ic, h) { ic.VM.Estack().PushVal(-1) return nil } ic.VM.Estack().PushVal(h) return nil } // engineGetScriptContainer returns transaction or block that contains the script // being run. 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") } ic.VM.Estack().PushVal(item) return nil } // storageDelete deletes stored key-value pair. 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()) 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. 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) } key := ic.VM.Estack().Pop().Bytes() si := ic.DAO.GetStorageItem(stc.ID, key) if si != nil && si.Value != nil { ic.VM.Estack().PushVal(si.Value) } else { ic.VM.Estack().PushVal(stackitem.Null{}) } return nil } // storageGetContext returns storage context (scripthash). func storageGetContext(ic *interop.Context) error { return storageGetContextInternal(ic, false) } // storageGetReadOnlyContext returns read-only context (scripthash). 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. 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, } ic.VM.Estack().PushVal(stackitem.NewInterop(sc)) return nil } 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. 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) } key := ic.VM.Estack().Pop().Bytes() value := ic.VM.Estack().Pop().Bytes() var flag int if getFlag { flag = int(ic.VM.Estack().Pop().BigInt().Int64()) } return putWithContextAndFlags(ic, stc, key, value, int(Constant)&flag != 0) } // storagePut puts key-value pair into the storage. func storagePut(ic *interop.Context) error { return storagePutInternal(ic, false) } // storagePutEx puts key-value pair with given flags into the storage. func storagePutEx(ic *interop.Context) error { return storagePutInternal(ic, true) } // storageContextAsReadOnly sets given context to read-only mode. 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 } ic.VM.Estack().PushVal(stackitem.NewInterop(stc)) return nil } // contractIsStandard checks if contract is standard (sig or multisig) contract. 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 } } } } ic.VM.Estack().PushVal(result) return nil } // contractCreateStandardAccount calculates contract scripthash for a given public key. func contractCreateStandardAccount(ic *interop.Context) error { h := ic.VM.Estack().Pop().Bytes() p, err := keys.NewPublicKeyFromBytes(h, elliptic.P256()) if err != nil { return err } ic.VM.Estack().PushVal(p.GetScriptHash().BytesBE()) return nil } // contractGetCallFlags returns current context calling flags. func contractGetCallFlags(ic *interop.Context) error { ic.VM.Estack().PushVal(ic.VM.Context().GetCallFlags()) return nil }