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

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package native
import (
"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/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 blockchainer.Blockchainer, 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
// Blockchainer 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 blockchainer.Blockchainer, item stackitem.Item) util.Uint256 {
bigindex, err := item.TryInteger()
if err == nil && bigindex.IsInt64() {
index := bigindex.Int64()
if index < 0 || 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(cd *dao.Cached, 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 cd.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(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),
})
}