package types
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import (
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"bytes"
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"errors"
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"fmt"
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"github.com/tendermint/tendermint/crypto/merkle"
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"github.com/tendermint/tendermint/crypto/tmhash"
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tmbytes "github.com/tendermint/tendermint/libs/bytes"
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)
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// Tx is an arbitrary byte array.
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// NOTE: Tx has no types at this level, so when wire encoded it's just length-prefixed.
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// Might we want types here ?
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type Tx []byte
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// Hash computes the TMHASH hash of the wire encoded transaction.
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func (tx Tx) Hash() []byte {
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return tmhash.Sum(tx)
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}
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// String returns the hex-encoded transaction as a string.
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func (tx Tx) String() string {
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return fmt.Sprintf("Tx{%X}", []byte(tx))
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}
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// Txs is a slice of Tx.
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type Txs []Tx
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// Hash returns the Merkle root hash of the transaction hashes.
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// i.e. the leaves of the tree are the hashes of the txs.
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func (txs Txs) Hash() []byte {
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// These allocations will be removed once Txs is switched to [][]byte,
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// ref #2603. This is because golang does not allow type casting slices without unsafe
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txBzs := make([][]byte, len(txs))
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for i := 0; i < len(txs); i++ {
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txBzs[i] = txs[i].Hash()
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}
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return merkle.HashFromByteSlices(txBzs)
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}
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// Index returns the index of this transaction in the list, or -1 if not found
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func (txs Txs) Index(tx Tx) int {
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for i := range txs {
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if bytes.Equal(txs[i], tx) {
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return i
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}
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}
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return -1
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}
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// IndexByHash returns the index of this transaction hash in the list, or -1 if not found
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func (txs Txs) IndexByHash(hash []byte) int {
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for i := range txs {
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if bytes.Equal(txs[i].Hash(), hash) {
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return i
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}
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}
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return -1
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}
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// Proof returns a simple merkle proof for this node.
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// Panics if i < 0 or i >= len(txs)
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// TODO: optimize this!
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func (txs Txs) Proof(i int) TxProof {
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l := len(txs)
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bzs := make([][]byte, l)
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for i := 0; i < l; i++ {
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bzs[i] = txs[i].Hash()
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}
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root, proofs := merkle.ProofsFromByteSlices(bzs)
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return TxProof{
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RootHash: root,
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Data: txs[i],
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Proof: *proofs[i],
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}
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}
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// TxProof represents a Merkle proof of the presence of a transaction in the Merkle tree.
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type TxProof struct {
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RootHash tmbytes.HexBytes `json:"root_hash"`
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Data Tx `json:"data"`
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Proof merkle.Proof `json:"proof"`
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}
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// Leaf returns the hash(tx), which is the leaf in the merkle tree which this proof refers to.
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func (tp TxProof) Leaf() []byte {
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return tp.Data.Hash()
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}
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// Validate verifies the proof. It returns nil if the RootHash matches the dataHash argument,
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// and if the proof is internally consistent. Otherwise, it returns a sensible error.
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func (tp TxProof) Validate(dataHash []byte) error {
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if !bytes.Equal(dataHash, tp.RootHash) {
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return errors.New("proof matches different data hash")
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}
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if tp.Proof.Index < 0 {
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return errors.New("proof index cannot be negative")
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}
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if tp.Proof.Total <= 0 {
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return errors.New("proof total must be positive")
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}
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valid := tp.Proof.Verify(tp.RootHash, tp.Leaf())
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if valid != nil {
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return errors.New("proof is not internally consistent")
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}
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return nil
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}
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