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99 lines
2.9 KiB
Go
99 lines
2.9 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// Package light implements on-demand retrieval capable state and chain objects
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// for the Ethereum Light Client.
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package light
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import (
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/ethdb"
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"github.com/ethereum/go-ethereum/rlp"
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"golang.org/x/net/context"
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)
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// OdrBackend is an interface to a backend service that handles odr retrievals
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type OdrBackend interface {
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Database() ethdb.Database
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Retrieve(ctx context.Context, req OdrRequest) error
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}
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// OdrRequest is an interface for retrieval requests
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type OdrRequest interface {
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StoreResult(db ethdb.Database)
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}
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// TrieRequest is the ODR request type for state/storage trie entries
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type TrieRequest struct {
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OdrRequest
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root common.Hash
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key []byte
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proof []rlp.RawValue
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}
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// StoreResult stores the retrieved data in local database
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func (req *TrieRequest) StoreResult(db ethdb.Database) {
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storeProof(db, req.proof)
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}
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// storeProof stores the new trie nodes obtained from a merkle proof in the database
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func storeProof(db ethdb.Database, proof []rlp.RawValue) {
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for _, buf := range proof {
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hash := crypto.Keccak256(buf)
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val, _ := db.Get(hash)
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if val == nil {
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db.Put(hash, buf)
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}
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}
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}
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// NodeDataRequest is the ODR request type for node data (used for retrieving contract code)
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type NodeDataRequest struct {
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OdrRequest
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hash common.Hash
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data []byte
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}
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// GetData returns the retrieved node data after a successful request
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func (req *NodeDataRequest) GetData() []byte {
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return req.data
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}
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// StoreResult stores the retrieved data in local database
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func (req *NodeDataRequest) StoreResult(db ethdb.Database) {
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db.Put(req.hash[:], req.GetData())
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}
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var sha3_nil = crypto.Keccak256Hash(nil)
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// retrieveNodeData tries to retrieve node data with the given hash from the network
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func retrieveNodeData(ctx context.Context, odr OdrBackend, hash common.Hash) ([]byte, error) {
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if hash == sha3_nil {
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return nil, nil
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}
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res, _ := odr.Database().Get(hash[:])
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if res != nil {
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return res, nil
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}
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r := &NodeDataRequest{hash: hash}
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if err := odr.Retrieve(ctx, r); err != nil {
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return nil, err
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} else {
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return r.GetData(), nil
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}
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}
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