package native import ( "fmt" "math" "math/big" "github.com/nspcc-dev/neo-go/pkg/core/block" "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/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 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) return l } // Metadata implements Contract interface. func (l *Ledger) Metadata() *interop.ContractMD { return &l.ContractMD } // Initialize implements Contract interface. func (l *Ledger) Initialize(ic *interop.Context) error { return nil } // OnPersist implements 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 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.Chain.CurrentBlockHash().BytesBE()) } // currentIndex implements currentIndex SC method. func (l *Ledger) currentIndex(ic *interop.Context, _ []stackitem.Item) stackitem.Item { return stackitem.Make(ic.Chain.BlockHeight()) } // getBlock implements getBlock SC method. func (l *Ledger) getBlock(ic *interop.Context, params []stackitem.Item) stackitem.Item { hash := getBlockHashFromItem(ic.Chain, params[0]) block, err := ic.Chain.GetBlock(hash) if err != nil || !isTraceableBlock(ic.Chain, block.Index) { return stackitem.Null{} } return BlockToStackItem(block) } // 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.Chain, h) { return stackitem.Null{} } return TransactionToStackItem(tx) } // 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.Chain, h) { return stackitem.Make(-1) } return stackitem.Make(h) } // getTransactionFromBlock returns transaction with the given index from the // block with height or hash specified. func (l *Ledger) getTransactionFromBlock(ic *interop.Context, params []stackitem.Item) stackitem.Item { hash := getBlockHashFromItem(ic.Chain, params[0]) index := toUint32(params[1]) block, err := ic.Chain.GetBlock(hash) if err != nil || !isTraceableBlock(ic.Chain, block.Index) { return stackitem.Null{} } if index >= uint32(len(block.Transactions)) { panic("wrong transaction index") } return TransactionToStackItem(block.Transactions[index]) } // isTraceableBlock defines whether we're able to give information about // the block with index specified. func isTraceableBlock(bc interop.Ledger, index uint32) bool { height := bc.BlockHeight() MaxTraceableBlocks := bc.GetConfig().MaxTraceableBlocks return index <= height && index+MaxTraceableBlocks > height } // getBlockHashFromItem converts given stackitem.Item to block hash using 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(bc interop.Ledger, 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) > bc.BlockHeight() { panic(fmt.Errorf("no block with index %d", index)) } return bc.GetHeaderHash(int(index)) } bytes, err := item.TryBytes() if err != nil { panic(err) } hash, err := util.Uint256DecodeBytesBE(bytes) if err != nil { panic(err) } return hash } // getTransactionAndHeight returns 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) { hashbytes, err := item.TryBytes() if err != nil { panic(err) } hash, err := util.Uint256DecodeBytesBE(hashbytes) if err != nil { panic(err) } return d.GetTransaction(hash) } // 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(new(big.Int).SetUint64(b.Nonce)), stackitem.NewBigInteger(big.NewInt(int64(b.Index))), stackitem.NewByteArray(b.NextConsensus.BytesBE()), stackitem.NewBigInteger(big.NewInt(int64(len(b.Transactions)))), }) } // 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), }) }