path: root/light/odr.go

// 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 (
    "context"
    "math/big"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/crypto"
    "github.com/ethereum/go-ethereum/ethdb"
    "github.com/ethereum/go-ethereum/rlp"
)

// NoOdr is the default context passed to an ODR capable function when the ODR
// service is not required.
var NoOdr = context.Background()

// 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)
}

// TrieID identifies a state or account storage trie
type TrieID struct {
    BlockHash, Root common.Hash
    BlockNumber     uint64
    AccKey          []byte
}

// StateTrieID returns a TrieID for a state trie belonging to a certain block
// header.
func StateTrieID(header *types.Header) *TrieID {
    return &TrieID{
        BlockHash:   header.Hash(),
        BlockNumber: header.Number.Uint64(),
        AccKey:      nil,
        Root:        header.Root,
    }
}

// StorageTrieID returns a TrieID for a contract storage trie at a given account
// of a given state trie. It also requires the root hash of the trie for
// checking Merkle proofs.
func StorageTrieID(state *TrieID, addr common.Address, root common.Hash) *TrieID {
    return &TrieID{
        BlockHash:   state.BlockHash,
        BlockNumber: state.BlockNumber,
        AccKey:      crypto.Keccak256(addr[:]),
        Root:        root,
    }
}

// TrieRequest is the ODR request type for state/storage trie entries
type TrieRequest struct {
    OdrRequest
    Id    *TrieID
    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)
        }
    }
}

// CodeRequest is the ODR request type for retrieving contract code
type CodeRequest struct {
    OdrRequest
    Id   *TrieID
    Hash common.Hash
    Data []byte
}

// StoreResult stores the retrieved data in local database
func (req *CodeRequest) StoreResult(db ethdb.Database) {
    db.Put(req.Hash[:], req.Data)
}

// BlockRequest is the ODR request type for retrieving block bodies
type BlockRequest struct {
    OdrRequest
    Hash   common.Hash
    Number uint64
    Rlp    []byte
}

// StoreResult stores the retrieved data in local database
func (req *BlockRequest) StoreResult(db ethdb.Database) {
    core.WriteBodyRLP(db, req.Hash, req.Number, req.Rlp)
}

// ReceiptsRequest is the ODR request type for retrieving block bodies
type ReceiptsRequest struct {
    OdrRequest
    Hash     common.Hash
    Number   uint64
    Receipts types.Receipts
}

// StoreResult stores the retrieved data in local database
func (req *ReceiptsRequest) StoreResult(db ethdb.Database) {
    core.WriteBlockReceipts(db, req.Hash, req.Number, req.Receipts)
}

// TrieRequest is the ODR request type for state/storage trie entries
type ChtRequest struct {
    OdrRequest
    ChtNum, BlockNum uint64
    ChtRoot          common.Hash
    Header           *types.Header
    Td               *big.Int
    Proof            []rlp.RawValue
}

// StoreResult stores the retrieved data in local database
func (req *ChtRequest) StoreResult(db ethdb.Database) {
    // if there is a canonical hash, there is a header too
    core.WriteHeader(db, req.Header)
    hash, num := req.Header.Hash(), req.Header.Number.Uint64()
    core.WriteTd(db, hash, num, req.Td)
    core.WriteCanonicalHash(db, hash, num)
    //storeProof(db, req.Proof)
}