ipld-eth-server/pkg/eth/ipld_retriever.go

// VulcanizeDB
// Copyright © 2019 Vulcanize

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.

// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package eth

import (
	"fmt"

	"github.com/ethereum/go-ethereum/statediff/trie_helpers"
	sdtypes "github.com/ethereum/go-ethereum/statediff/types"
	"github.com/jmoiron/sqlx"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/rlp"
	"github.com/lib/pq"
)

const (
	// node type removed value.
	// https://github.com/vulcanize/go-ethereum/blob/271f4d01e7e2767ffd8e0cd469bf545be96f2a84/statediff/indexer/helpers.go#L34
	removedNode = 3

	RetrieveHeadersByHashesPgStr = `SELECT cid, data
								FROM eth.header_cids
									INNER JOIN public.blocks ON (header_cids.mh_key = blocks.key)
								WHERE block_hash = ANY($1::VARCHAR(66)[])`
	RetrieveHeadersByBlockNumberPgStr = `SELECT cid, data
								FROM eth.header_cids
									INNER JOIN public.blocks ON (header_cids.mh_key = blocks.key)
								WHERE block_number = $1`
	RetrieveHeaderByHashPgStr = `SELECT cid, data
								FROM eth.header_cids
									INNER JOIN public.blocks ON (header_cids.mh_key = blocks.key)
								WHERE block_hash = $1`
	RetrieveUnclesByHashesPgStr = `SELECT cid, data
								FROM eth.uncle_cids
									INNER JOIN public.blocks ON (uncle_cids.mh_key = blocks.key)
								WHERE block_hash = ANY($1::VARCHAR(66)[])`
	RetrieveUnclesByBlockHashPgStr = `SELECT uncle_cids.cid, data
										FROM eth.uncle_cids
											INNER JOIN eth.header_cids ON (uncle_cids.header_id = header_cids.block_hash)
											INNER JOIN public.blocks ON (uncle_cids.mh_key = blocks.key)
										WHERE block_hash = $1`
	RetrieveUnclesByBlockNumberPgStr = `SELECT uncle_cids.cid, data
										FROM eth.uncle_cids
											INNER JOIN eth.header_cids ON (uncle_cids.header_id = header_cids.block_hash)
											INNER JOIN public.blocks ON (uncle_cids.mh_key = blocks.key)
										WHERE block_number = $1`
	RetrieveUncleByHashPgStr = `SELECT cid, data
								FROM eth.uncle_cids
									INNER JOIN public.blocks ON (uncle_cids.mh_key = blocks.key)
								WHERE block_hash = $1`
	RetrieveTransactionsByHashesPgStr = `SELECT cid, data
									FROM eth.transaction_cids
										INNER JOIN public.blocks ON (transaction_cids.mh_key = blocks.key)
									WHERE tx_hash = ANY($1::VARCHAR(66)[])`
	RetrieveTransactionsByBlockHashPgStr = `SELECT transaction_cids.cid, data
											FROM eth.transaction_cids
												INNER JOIN eth.header_cids ON (transaction_cids.header_id = header_cids.block_hash)
												INNER JOIN public.blocks ON (transaction_cids.mh_key = blocks.key)
											WHERE block_hash = $1
											ORDER BY eth.transaction_cids.index ASC`
	RetrieveTransactionsByBlockNumberPgStr = `SELECT transaction_cids.cid, data
											FROM eth.transaction_cids
												INNER JOIN eth.header_cids ON (transaction_cids.header_id = header_cids.block_hash)
												INNER JOIN public.blocks ON (transaction_cids.mh_key = blocks.key)
											WHERE block_number = $1
											ORDER BY eth.transaction_cids.index ASC`
	RetrieveTransactionByHashPgStr = `SELECT cid, data
									FROM eth.transaction_cids
										INNER JOIN public.blocks ON (transaction_cids.mh_key = blocks.key)
									WHERE tx_hash = $1`
	RetrieveReceiptsByTxHashesPgStr = `SELECT receipt_cids.leaf_cid, data
									FROM eth.receipt_cids
										INNER JOIN eth.transaction_cids ON (receipt_cids.tx_id = transaction_cids.tx_hash)
										INNER JOIN public.blocks ON (receipt_cids.leaf_mh_key = blocks.key)
									WHERE tx_hash = ANY($1::VARCHAR(66)[])`
	RetrieveReceiptsByBlockHashPgStr = `SELECT receipt_cids.leaf_cid, data, eth.transaction_cids.tx_hash
										FROM eth.receipt_cids
											INNER JOIN eth.transaction_cids ON (receipt_cids.tx_id = transaction_cids.tx_hash)
											INNER JOIN eth.header_cids ON (transaction_cids.header_id = header_cids.block_hash)
											INNER JOIN public.blocks ON (receipt_cids.leaf_mh_key = blocks.key)
										WHERE block_hash = $1
										ORDER BY eth.transaction_cids.index ASC`
	RetrieveReceiptsByBlockNumberPgStr = `SELECT receipt_cids.leaf_cid, data
										FROM eth.receipt_cids
											INNER JOIN eth.transaction_cids ON (receipt_cids.tx_id = transaction_cids.tx_hash)
											INNER JOIN eth.header_cids ON (transaction_cids.header_id = header_cids.block_hash)
											INNER JOIN public.blocks ON (receipt_cids.leaf_mh_key = blocks.key)
										WHERE block_number = $1
										ORDER BY eth.transaction_cids.index ASC`
	RetrieveReceiptByTxHashPgStr = `SELECT receipt_cids.leaf_cid, data
									FROM eth.receipt_cids
										INNER JOIN eth.transaction_cids ON (receipt_cids.tx_id = transaction_cids.tx_hash)
										INNER JOIN public.blocks ON (receipt_cids.leaf_mh_key = blocks.key)
									WHERE tx_hash = $1`
	RetrieveAccountByLeafKeyAndBlockHashPgStr = `SELECT state_cids.cid, data, state_cids.node_type
												FROM eth.state_cids
													INNER JOIN eth.header_cids ON (state_cids.header_id = header_cids.block_hash)
													INNER JOIN public.blocks ON (state_cids.mh_key = blocks.key)
												WHERE state_leaf_key = $1
												AND block_number <= (SELECT block_number
																	FROM eth.header_cids
																	WHERE block_hash = $2)
												AND header_cids.block_hash = (SELECT canonical_header_hash(block_number))
												ORDER BY block_number DESC
												LIMIT 1`
	RetrieveAccountByLeafKeyAndBlockNumberPgStr = `SELECT state_cids.cid, data, state_cids.node_type
													FROM eth.state_cids
														INNER JOIN eth.header_cids ON (state_cids.header_id = header_cids.block_hash)
														INNER JOIN public.blocks ON (state_cids.mh_key = blocks.key)
													WHERE state_leaf_key = $1
													AND block_number <= $2
													ORDER BY block_number DESC
													LIMIT 1`
	RetrieveStorageLeafByAddressHashAndLeafKeyAndBlockNumberPgStr = `SELECT storage_cids.cid, data, storage_cids.node_type, was_state_leaf_removed($1, $3) AS state_leaf_removed
																	FROM eth.storage_cids
																		INNER JOIN eth.state_cids ON (storage_cids.header_id = state_cids.header_id)
																		INNER JOIN eth.header_cids ON (state_cids.header_id = header_cids.block_hash)
																		INNER JOIN public.blocks ON (storage_cids.mh_key = blocks.key)
																	WHERE state_leaf_key = $1
																	AND storage_leaf_key = $2
																	AND block_number <= $3
																	ORDER BY block_number DESC
																	LIMIT 1`
	RetrieveStorageLeafByAddressHashAndLeafKeyAndBlockHashPgStr = `SELECT storage_cids.cid, data, storage_cids.node_type, was_state_leaf_removed($1, $3) AS state_leaf_removed
																	FROM eth.storage_cids
																		INNER JOIN eth.state_cids ON (storage_cids.header_id = state_cids.header_id)
																		INNER JOIN eth.header_cids ON (state_cids.header_id = header_cids.block_hash)
																		INNER JOIN public.blocks ON (storage_cids.mh_key = blocks.key)
																	WHERE state_leaf_key = $1
																	AND storage_leaf_key = $2
																	AND block_number <= (SELECT block_number
																						FROM eth.header_cids
																						WHERE block_hash = $3)
																	AND header_cids.block_hash = (SELECT canonical_header_hash(block_number))
																	ORDER BY block_number DESC
																	LIMIT 1`
)

var EmptyNodeValue = make([]byte, common.HashLength)

type rctIpldResult struct {
	LeafCID string `db:"leaf_cid"`
	Data    []byte `db:"data"`
	TxHash  string `db:"tx_hash"`
}

type ipldResult struct {
	CID    string `db:"cid"`
	Data   []byte `db:"data"`
	TxHash string `db:"tx_hash"`
}

type IPLDRetriever struct {
	db *sqlx.DB
}

func NewIPLDRetriever(db *sqlx.DB) *IPLDRetriever {
	return &IPLDRetriever{
		db: db,
	}
}

// RetrieveHeadersByHashes returns the cids and rlp bytes for the headers corresponding to the provided block hashes
func (r *IPLDRetriever) RetrieveHeadersByHashes(hashes []common.Hash) ([]string, [][]byte, error) {
	headerResults := make([]ipldResult, 0)
	hashStrs := make([]string, len(hashes))
	for i, hash := range hashes {
		hashStrs[i] = hash.Hex()
	}
	if err := r.db.Select(&headerResults, RetrieveHeadersByHashesPgStr, pq.Array(hashStrs)); err != nil {
		return nil, nil, err
	}
	cids := make([]string, len(headerResults))
	headers := make([][]byte, len(headerResults))
	for i, res := range headerResults {
		cids[i] = res.CID
		headers[i] = res.Data
	}
	return cids, headers, nil
}

// RetrieveHeadersByBlockNumber returns the cids and rlp bytes for the headers corresponding to the provided block number
// This can return more than one result since there can be more than one header (non-canonical headers)
func (r *IPLDRetriever) RetrieveHeadersByBlockNumber(number uint64) ([]string, [][]byte, error) {
	headerResults := make([]ipldResult, 0)
	if err := r.db.Select(&headerResults, RetrieveHeadersByBlockNumberPgStr, number); err != nil {
		return nil, nil, err
	}
	cids := make([]string, len(headerResults))
	headers := make([][]byte, len(headerResults))
	for i, res := range headerResults {
		cids[i] = res.CID
		headers[i] = res.Data
	}
	return cids, headers, nil
}

// RetrieveHeaderByHash returns the cid and rlp bytes for the header corresponding to the provided block hash
func (r *IPLDRetriever) RetrieveHeaderByHash(hash common.Hash) (string, []byte, error) {
	headerResult := new(ipldResult)
	return headerResult.CID, headerResult.Data, r.db.Get(headerResult, RetrieveHeaderByHashPgStr, hash.Hex())
}

// RetrieveUnclesByHashes returns the cids and rlp bytes for the uncles corresponding to the provided uncle hashes
func (r *IPLDRetriever) RetrieveUnclesByHashes(hashes []common.Hash) ([]string, [][]byte, error) {
	uncleResults := make([]ipldResult, 0)
	hashStrs := make([]string, len(hashes))
	for i, hash := range hashes {
		hashStrs[i] = hash.Hex()
	}
	if err := r.db.Select(&uncleResults, RetrieveUnclesByHashesPgStr, pq.Array(hashStrs)); err != nil {
		return nil, nil, err
	}
	cids := make([]string, len(uncleResults))
	uncles := make([][]byte, len(uncleResults))
	for i, res := range uncleResults {
		cids[i] = res.CID
		uncles[i] = res.Data
	}
	return cids, uncles, nil
}

// RetrieveUnclesByBlockHash returns the cids and rlp bytes for the uncles corresponding to the provided block hash (of non-omner root block)
func (r *IPLDRetriever) RetrieveUnclesByBlockHash(hash common.Hash) ([]string, [][]byte, error) {
	uncleResults := make([]ipldResult, 0)
	if err := r.db.Select(&uncleResults, RetrieveUnclesByBlockHashPgStr, hash.Hex()); err != nil {
		return nil, nil, err
	}
	cids := make([]string, len(uncleResults))
	uncles := make([][]byte, len(uncleResults))
	for i, res := range uncleResults {
		cids[i] = res.CID
		uncles[i] = res.Data
	}
	return cids, uncles, nil
}

// RetrieveUnclesByBlockNumber returns the cids and rlp bytes for the uncles corresponding to the provided block number (of non-omner root block)
func (r *IPLDRetriever) RetrieveUnclesByBlockNumber(number uint64) ([]string, [][]byte, error) {
	uncleResults := make([]ipldResult, 0)
	if err := r.db.Select(&uncleResults, RetrieveUnclesByBlockNumberPgStr, number); err != nil {
		return nil, nil, err
	}
	cids := make([]string, len(uncleResults))
	uncles := make([][]byte, len(uncleResults))
	for i, res := range uncleResults {
		cids[i] = res.CID
		uncles[i] = res.Data
	}
	return cids, uncles, nil
}

// RetrieveUncleByHash returns the cid and rlp bytes for the uncle corresponding to the provided uncle hash
func (r *IPLDRetriever) RetrieveUncleByHash(hash common.Hash) (string, []byte, error) {
	uncleResult := new(ipldResult)
	return uncleResult.CID, uncleResult.Data, r.db.Get(uncleResult, RetrieveUncleByHashPgStr, hash.Hex())
}

// RetrieveTransactionsByHashes returns the cids and rlp bytes for the transactions corresponding to the provided tx hashes
func (r *IPLDRetriever) RetrieveTransactionsByHashes(hashes []common.Hash) ([]string, [][]byte, error) {
	txResults := make([]ipldResult, 0)
	hashStrs := make([]string, len(hashes))
	for i, hash := range hashes {
		hashStrs[i] = hash.Hex()
	}
	if err := r.db.Select(&txResults, RetrieveTransactionsByHashesPgStr, pq.Array(hashStrs)); err != nil {
		return nil, nil, err
	}
	cids := make([]string, len(txResults))
	txs := make([][]byte, len(txResults))
	for i, res := range txResults {
		cids[i] = res.CID
		txs[i] = res.Data
	}
	return cids, txs, nil
}

// RetrieveTransactionsByBlockHash returns the cids and rlp bytes for the transactions corresponding to the provided block hash
func (r *IPLDRetriever) RetrieveTransactionsByBlockHash(hash common.Hash) ([]string, [][]byte, error) {
	txResults := make([]ipldResult, 0)
	if err := r.db.Select(&txResults, RetrieveTransactionsByBlockHashPgStr, hash.Hex()); err != nil {
		return nil, nil, err
	}
	cids := make([]string, len(txResults))
	txs := make([][]byte, len(txResults))
	for i, res := range txResults {
		cids[i] = res.CID
		txs[i] = res.Data
	}
	return cids, txs, nil
}

// RetrieveTransactionsByBlockNumber returns the cids and rlp bytes for the transactions corresponding to the provided block number
func (r *IPLDRetriever) RetrieveTransactionsByBlockNumber(number uint64) ([]string, [][]byte, error) {
	txResults := make([]ipldResult, 0)
	if err := r.db.Select(&txResults, RetrieveTransactionsByBlockNumberPgStr, number); err != nil {
		return nil, nil, err
	}
	cids := make([]string, len(txResults))
	txs := make([][]byte, len(txResults))
	for i, res := range txResults {
		cids[i] = res.CID
		txs[i] = res.Data
	}
	return cids, txs, nil
}

// RetrieveTransactionByTxHash returns the cid and rlp bytes for the transaction corresponding to the provided tx hash
func (r *IPLDRetriever) RetrieveTransactionByTxHash(hash common.Hash) (string, []byte, error) {
	txResult := new(ipldResult)
	return txResult.CID, txResult.Data, r.db.Get(txResult, RetrieveTransactionByHashPgStr, hash.Hex())
}

// DecodeLeafNode decodes the leaf node data
func DecodeLeafNode(node []byte) ([]byte, error) {
	var nodeElements []interface{}
	if err := rlp.DecodeBytes(node, &nodeElements); err != nil {
		return nil, err
	}
	ty, err := trie_helpers.CheckKeyType(nodeElements)
	if err != nil {
		return nil, err
	}

	if ty != sdtypes.Leaf {
		return nil, fmt.Errorf("expected leaf node but found %s", ty)
	}
	return nodeElements[1].([]byte), nil
}

// RetrieveReceiptsByTxHashes returns the cids and rlp bytes for the receipts corresponding to the provided tx hashes
func (r *IPLDRetriever) RetrieveReceiptsByTxHashes(hashes []common.Hash) ([]string, [][]byte, error) {
	rctResults := make([]rctIpldResult, 0)
	hashStrs := make([]string, len(hashes))
	for i, hash := range hashes {
		hashStrs[i] = hash.Hex()
	}
	if err := r.db.Select(&rctResults, RetrieveReceiptsByTxHashesPgStr, pq.Array(hashStrs)); err != nil {
		return nil, nil, err
	}
	cids := make([]string, len(rctResults))
	rcts := make([][]byte, len(rctResults))
	for i, res := range rctResults {
		cids[i] = res.LeafCID
		nodeVal, err := DecodeLeafNode(res.Data)
		if err != nil {
			return nil, nil, err
		}
		rcts[i] = nodeVal
	}
	return cids, rcts, nil
}

// RetrieveReceiptsByBlockHash returns the cids and rlp bytes for the receipts corresponding to the provided block hash.
// cid returned corresponds to the leaf node data which contains the receipt.
func (r *IPLDRetriever) RetrieveReceiptsByBlockHash(hash common.Hash) ([]string, [][]byte, []common.Hash, error) {
	rctResults := make([]rctIpldResult, 0)
	if err := r.db.Select(&rctResults, RetrieveReceiptsByBlockHashPgStr, hash.Hex()); err != nil {
		return nil, nil, nil, err
	}
	cids := make([]string, len(rctResults))
	rcts := make([][]byte, len(rctResults))
	txs := make([]common.Hash, len(rctResults))

	for i, res := range rctResults {
		cids[i] = res.LeafCID
		nodeVal, err := DecodeLeafNode(res.Data)
		if err != nil {
			return nil, nil, nil, err
		}
		rcts[i] = nodeVal
		txs[i] = common.HexToHash(res.TxHash)
	}

	return cids, rcts, txs, nil
}

// RetrieveReceiptsByBlockNumber returns the cids and rlp bytes for the receipts corresponding to the provided block hash.
// cid returned corresponds to the leaf node data which contains the receipt.
func (r *IPLDRetriever) RetrieveReceiptsByBlockNumber(number uint64) ([]string, [][]byte, error) {
	rctResults := make([]rctIpldResult, 0)
	if err := r.db.Select(&rctResults, RetrieveReceiptsByBlockNumberPgStr, number); err != nil {
		return nil, nil, err
	}
	cids := make([]string, len(rctResults))
	rcts := make([][]byte, len(rctResults))
	for i, res := range rctResults {
		cids[i] = res.LeafCID
		nodeVal, err := DecodeLeafNode(res.Data)
		if err != nil {
			return nil, nil, err
		}
		rcts[i] = nodeVal
	}
	return cids, rcts, nil
}

// RetrieveReceiptByHash returns the cid and rlp bytes for the receipt corresponding to the provided tx hash.
// cid returned corresponds to the leaf node data which contains the receipt.
func (r *IPLDRetriever) RetrieveReceiptByHash(hash common.Hash) (string, []byte, error) {
	rctResult := new(rctIpldResult)
	if err := r.db.Select(&rctResult, RetrieveReceiptByTxHashPgStr, hash.Hex()); err != nil {
		return "", nil, err
	}

	nodeVal, err := DecodeLeafNode(rctResult.Data)
	if err != nil {
		return "", nil, err
	}
	return rctResult.LeafCID, nodeVal, nil
}

type nodeInfo struct {
	CID              string `db:"cid"`
	Data             []byte `db:"data"`
	NodeType         int    `db:"node_type"`
	StateLeafRemoved bool   `db:"state_leaf_removed"`
}

// RetrieveAccountByAddressAndBlockHash returns the cid and rlp bytes for the account corresponding to the provided address and block hash
// TODO: ensure this handles deleted accounts appropriately
func (r *IPLDRetriever) RetrieveAccountByAddressAndBlockHash(address common.Address, hash common.Hash) (string, []byte, error) {
	accountResult := new(nodeInfo)
	leafKey := crypto.Keccak256Hash(address.Bytes())
	if err := r.db.Get(accountResult, RetrieveAccountByLeafKeyAndBlockHashPgStr, leafKey.Hex(), hash.Hex()); err != nil {
		return "", nil, err
	}

	if accountResult.NodeType == removedNode {
		return "", EmptyNodeValue, nil
	}

	var i []interface{}
	if err := rlp.DecodeBytes(accountResult.Data, &i); err != nil {
		return "", nil, fmt.Errorf("error decoding state leaf node rlp: %s", err.Error())
	}
	if len(i) != 2 {
		return "", nil, fmt.Errorf("eth IPLDRetriever expected state leaf node rlp to decode into two elements")
	}
	return accountResult.CID, i[1].([]byte), nil
}

// RetrieveAccountByAddressAndBlockNumber returns the cid and rlp bytes for the account corresponding to the provided address and block number
// This can return a non-canonical account
func (r *IPLDRetriever) RetrieveAccountByAddressAndBlockNumber(address common.Address, number uint64) (string, []byte, error) {
	accountResult := new(nodeInfo)
	leafKey := crypto.Keccak256Hash(address.Bytes())
	if err := r.db.Get(accountResult, RetrieveAccountByLeafKeyAndBlockNumberPgStr, leafKey.Hex(), number); err != nil {
		return "", nil, err
	}

	if accountResult.NodeType == removedNode {
		return "", EmptyNodeValue, nil
	}

	var i []interface{}
	if err := rlp.DecodeBytes(accountResult.Data, &i); err != nil {
		return "", nil, fmt.Errorf("error decoding state leaf node rlp: %s", err.Error())
	}
	if len(i) != 2 {
		return "", nil, fmt.Errorf("eth IPLDRetriever expected state leaf node rlp to decode into two elements")
	}
	return accountResult.CID, i[1].([]byte), nil
}

// RetrieveStorageAtByAddressAndStorageSlotAndBlockHash returns the cid and rlp bytes for the storage value corresponding to the provided address, storage slot, and block hash
func (r *IPLDRetriever) RetrieveStorageAtByAddressAndStorageSlotAndBlockHash(address common.Address, key, hash common.Hash) (string, []byte, []byte, error) {
	storageResult := new(nodeInfo)
	stateLeafKey := crypto.Keccak256Hash(address.Bytes())
	storageHash := crypto.Keccak256Hash(key.Bytes())
	if err := r.db.Get(storageResult, RetrieveStorageLeafByAddressHashAndLeafKeyAndBlockHashPgStr, stateLeafKey.Hex(), storageHash.Hex(), hash.Hex()); err != nil {
		return "", nil, nil, err
	}
	if storageResult.StateLeafRemoved || storageResult.NodeType == removedNode {
		return "", EmptyNodeValue, EmptyNodeValue, nil
	}
	var i []interface{}
	if err := rlp.DecodeBytes(storageResult.Data, &i); err != nil {
		err = fmt.Errorf("error decoding storage leaf node rlp: %s", err.Error())
		return "", nil, nil, err
	}
	if len(i) != 2 {
		return "", nil, nil, fmt.Errorf("eth IPLDRetriever expected storage leaf node rlp to decode into two elements")
	}
	return storageResult.CID, storageResult.Data, i[1].([]byte), nil
}

// RetrieveStorageAtByAddressAndStorageKeyAndBlockNumber returns the cid and rlp bytes for the storage value corresponding to the provided address, storage key, and block number
// This can retrun a non-canonical value
func (r *IPLDRetriever) RetrieveStorageAtByAddressAndStorageKeyAndBlockNumber(address common.Address, storageLeafKey common.Hash, number uint64) (string, []byte, error) {
	storageResult := new(nodeInfo)
	stateLeafKey := crypto.Keccak256Hash(address.Bytes())
	if err := r.db.Get(storageResult, RetrieveStorageLeafByAddressHashAndLeafKeyAndBlockNumberPgStr, stateLeafKey.Hex(), storageLeafKey.Hex(), number); err != nil {
		return "", nil, err
	}

	if storageResult.StateLeafRemoved || storageResult.NodeType == removedNode {
		return "", EmptyNodeValue, nil
	}
	var i []interface{}
	if err := rlp.DecodeBytes(storageResult.Data, &i); err != nil {
		return "", nil, fmt.Errorf("error decoding storage leaf node rlp: %s", err.Error())
	}
	if len(i) != 2 {
		return "", nil, fmt.Errorf("eth IPLDRetriever expected storage leaf node rlp to decode into two elements")
	}
	return storageResult.CID, i[1].([]byte), nil
}