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// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
// Package light implements on-demand retrieval capable state and chain objects
// for the Ethereum Light Client.
package light
import (
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/rlp"
"golang.org/x/net/context"
)
// OdrBackend is an interface to a backend service that handles odr retrievals
type OdrBackend interface {
Database() ethdb.Database
Retrieve(ctx context.Context, req OdrRequest) error
}
// OdrRequest is an interface for retrieval requests
type OdrRequest interface {
StoreResult(db ethdb.Database)
}
// TrieRequest is the ODR request type for state/storage trie entries
type TrieRequest struct {
OdrRequest
root common.Hash
key []byte
proof []rlp.RawValue
}
// StoreResult stores the retrieved data in local database
func (req *TrieRequest) StoreResult(db ethdb.Database) {
storeProof(db, req.proof)
}
// storeProof stores the new trie nodes obtained from a merkle proof in the database
func storeProof(db ethdb.Database, proof []rlp.RawValue) {
for _, buf := range proof {
hash := crypto.Keccak256(buf)
val, _ := db.Get(hash)
if val == nil {
db.Put(hash, buf)
}
}
}
// NodeDataRequest is the ODR request type for node data (used for retrieving contract code)
type NodeDataRequest struct {
OdrRequest
hash common.Hash
data []byte
}
// GetData returns the retrieved node data after a successful request
func (req *NodeDataRequest) GetData() []byte {
return req.data
}
// StoreResult stores the retrieved data in local database
func (req *NodeDataRequest) StoreResult(db ethdb.Database) {
db.Put(req.hash[:], req.GetData())
}
var sha3_nil = crypto.Keccak256Hash(nil)
// retrieveNodeData tries to retrieve node data with the given hash from the network
func retrieveNodeData(ctx context.Context, odr OdrBackend, hash common.Hash) ([]byte, error) {
if hash == sha3_nil {
return nil, nil
}
res, _ := odr.Database().Get(hash[:])
if res != nil {
return res, nil
}
r := &NodeDataRequest{hash: hash}
if err := odr.Retrieve(ctx, r); err != nil {
return nil, err
} else {
return r.GetData(), nil
}
}
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