package native import ( "fmt" "math" "math/big" "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/native/nativenames" "github.com/nspcc-dev/neo-go/pkg/core/transaction" "github.com/nspcc-dev/neo-go/pkg/smartcontract" "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/util" "github.com/nspcc-dev/neo-go/pkg/vm" "github.com/nspcc-dev/neo-go/pkg/vm/stackitem" ) // Ledger provides an interface to blocks/transactions storage for smart // contracts. It's not a part of the proper chain's state, so it's just a // proxy between regular Blockchain/DAO interface and smart contracts. type Ledger struct { interop.ContractMD } const ledgerContractID = -4 // newLedger creates a new Ledger native contract. func newLedger() *Ledger { var l = &Ledger{ ContractMD: *interop.NewContractMD(nativenames.Ledger, ledgerContractID), } defer l.UpdateHash() desc := newDescriptor("currentHash", smartcontract.Hash256Type) md := newMethodAndPrice(l.currentHash, 1<<15, callflag.ReadStates) l.AddMethod(md, desc) desc = newDescriptor("currentIndex", smartcontract.IntegerType) md = newMethodAndPrice(l.currentIndex, 1<<15, callflag.ReadStates) l.AddMethod(md, desc) desc = newDescriptor("getBlock", smartcontract.ArrayType, manifest.NewParameter("indexOrHash", smartcontract.ByteArrayType)) md = newMethodAndPrice(l.getBlock, 1<<15, callflag.ReadStates) l.AddMethod(md, desc) desc = newDescriptor("getTransaction", smartcontract.ArrayType, manifest.NewParameter("hash", smartcontract.Hash256Type)) md = newMethodAndPrice(l.getTransaction, 1<<15, callflag.ReadStates) l.AddMethod(md, desc) desc = newDescriptor("getTransactionHeight", smartcontract.IntegerType, manifest.NewParameter("hash", smartcontract.Hash256Type)) md = newMethodAndPrice(l.getTransactionHeight, 1<<15, callflag.ReadStates) l.AddMethod(md, desc) desc = newDescriptor("getTransactionFromBlock", smartcontract.ArrayType, manifest.NewParameter("blockIndexOrHash", smartcontract.ByteArrayType), manifest.NewParameter("txIndex", smartcontract.IntegerType)) md = newMethodAndPrice(l.getTransactionFromBlock, 1<<16, callflag.ReadStates) l.AddMethod(md, desc) desc = newDescriptor("getTransactionSigners", smartcontract.ArrayType, manifest.NewParameter("hash", smartcontract.Hash256Type)) md = newMethodAndPrice(l.getTransactionSigners, 1<<15, callflag.ReadStates) l.AddMethod(md, desc) desc = newDescriptor("getTransactionVMState", smartcontract.IntegerType, manifest.NewParameter("hash", smartcontract.Hash256Type)) md = newMethodAndPrice(l.getTransactionVMState, 1<<15, callflag.ReadStates) l.AddMethod(md, desc) return l } // Metadata implements the Contract interface. func (l *Ledger) Metadata() *interop.ContractMD { return &l.ContractMD } // Initialize implements the Contract interface. func (l *Ledger) Initialize(ic *interop.Context) error { return nil } // OnPersist implements the Contract interface. func (l *Ledger) OnPersist(ic *interop.Context) error { // Actual block/tx processing is done in Blockchain.storeBlock(). // Even though C# node add them to storage here, they're not // accessible to smart contracts (see isTraceableBlock()), thus // the end effect is the same. return nil } // PostPersist implements the Contract interface. func (l *Ledger) PostPersist(ic *interop.Context) error { return nil // Actual block/tx processing is done in Blockchain.storeBlock(). } // currentHash implements currentHash SC method. func (l *Ledger) currentHash(ic *interop.Context, _ []stackitem.Item) stackitem.Item { return stackitem.Make(ic.CurrentBlockHash().BytesBE()) } // currentIndex implements currentIndex SC method. func (l *Ledger) currentIndex(ic *interop.Context, _ []stackitem.Item) stackitem.Item { return stackitem.Make(ic.BlockHeight()) } // getBlock implements getBlock SC method. func (l *Ledger) getBlock(ic *interop.Context, params []stackitem.Item) stackitem.Item { hash := getBlockHashFromItem(ic, params[0]) block, err := ic.GetBlock(hash) if err != nil || !isTraceableBlock(ic, block.Index) { return stackitem.Null{} } return block.ToStackItem() } // getTransaction returns transaction to the SC. func (l *Ledger) getTransaction(ic *interop.Context, params []stackitem.Item) stackitem.Item { tx, h, err := getTransactionAndHeight(ic.DAO, params[0]) if err != nil || !isTraceableBlock(ic, h) { return stackitem.Null{} } return tx.ToStackItem() } // getTransactionHeight returns transaction height to the SC. func (l *Ledger) getTransactionHeight(ic *interop.Context, params []stackitem.Item) stackitem.Item { _, h, err := getTransactionAndHeight(ic.DAO, params[0]) if err != nil || !isTraceableBlock(ic, h) { return stackitem.Make(-1) } return stackitem.Make(h) } // getTransactionFromBlock returns a transaction with the given index from the // block with the height or hash specified. func (l *Ledger) getTransactionFromBlock(ic *interop.Context, params []stackitem.Item) stackitem.Item { hash := getBlockHashFromItem(ic, params[0]) index := toUint32(params[1]) block, err := ic.GetBlock(hash) if err != nil || !isTraceableBlock(ic, block.Index) { return stackitem.Null{} } if index >= uint32(len(block.Transactions)) { panic("wrong transaction index") } return block.Transactions[index].ToStackItem() } // getTransactionSigners returns transaction signers to the SC. func (l *Ledger) getTransactionSigners(ic *interop.Context, params []stackitem.Item) stackitem.Item { tx, h, err := getTransactionAndHeight(ic.DAO, params[0]) if err != nil || !isTraceableBlock(ic, h) { return stackitem.Null{} } return SignersToStackItem(tx.Signers) } // getTransactionVMState returns VM state got after transaction invocation. func (l *Ledger) getTransactionVMState(ic *interop.Context, params []stackitem.Item) stackitem.Item { hash, err := getUint256FromItem(params[0]) if err != nil { panic(err) } h, _, aer, err := ic.DAO.GetTxExecResult(hash) if err != nil || !isTraceableBlock(ic, h) { return stackitem.Make(vm.NoneState) } return stackitem.Make(aer.VMState) } // isTraceableBlock defines whether we're able to give information about // the block with the index specified. func isTraceableBlock(ic *interop.Context, index uint32) bool { height := ic.BlockHeight() MaxTraceableBlocks := ic.Chain.GetConfig().MaxTraceableBlocks return index <= height && index+MaxTraceableBlocks > height } // getBlockHashFromItem converts the given stackitem.Item to a block hash using the given // Ledger if needed. Interop functions accept both block numbers and // block hashes as parameters, thus this function is needed. It's supposed to // be called within VM context, so it panics if anything goes wrong. func getBlockHashFromItem(ic *interop.Context, item stackitem.Item) util.Uint256 { bigindex, err := item.TryInteger() if err == nil && bigindex.IsUint64() { index := bigindex.Uint64() if index > math.MaxUint32 { panic("bad block index") } if uint32(index) > ic.BlockHeight() { panic(fmt.Errorf("no block with index %d", index)) } return ic.Chain.GetHeaderHash(int(index)) } hash, err := getUint256FromItem(item) if err != nil { panic(err) } return hash } func getUint256FromItem(item stackitem.Item) (util.Uint256, error) { hashbytes, err := item.TryBytes() if err != nil { return util.Uint256{}, fmt.Errorf("failed to get hash bytes: %w", err) } hash, err := util.Uint256DecodeBytesBE(hashbytes) if err != nil { return util.Uint256{}, fmt.Errorf("failed to decode hash: %w", err) } return hash, nil } // getTransactionAndHeight returns a transaction and its height if it's present // on the chain. It panics if anything goes wrong. func getTransactionAndHeight(d *dao.Simple, item stackitem.Item) (*transaction.Transaction, uint32, error) { hash, err := getUint256FromItem(item) if err != nil { panic(err) } return d.GetTransaction(hash) } // SignersToStackItem converts transaction.Signers to stackitem.Item. func SignersToStackItem(signers []transaction.Signer) stackitem.Item { res := make([]stackitem.Item, len(signers)) for i, s := range signers { contracts := make([]stackitem.Item, len(s.AllowedContracts)) for j, c := range s.AllowedContracts { contracts[j] = stackitem.NewByteArray(c.BytesBE()) } groups := make([]stackitem.Item, len(s.AllowedGroups)) for j, g := range s.AllowedGroups { groups[j] = stackitem.NewByteArray(g.Bytes()) } rules := make([]stackitem.Item, len(s.Rules)) for j, r := range s.Rules { rules[j] = r.ToStackItem() } res[i] = stackitem.NewArray([]stackitem.Item{ stackitem.NewByteArray(s.Account.BytesBE()), stackitem.NewBigInteger(big.NewInt(int64(s.Scopes))), stackitem.NewArray(contracts), stackitem.NewArray(groups), stackitem.NewArray(rules), }) } return stackitem.NewArray(res) }