path: root/eth/downloader/fakepeer.go

// Copyright 2017 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 downloader

import (
    "math/big"

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

// FakePeer is a mock downloader peer that operates on a local database instance
// instead of being an actual live node. It's useful for testing and to implement
// sync commands from an existing local database.
type FakePeer struct {
    id string
    db ethdb.Database
    hc *core.HeaderChain
    dl *Downloader
}

// NewFakePeer creates a new mock downloader peer with the given data sources.
func NewFakePeer(id string, db ethdb.Database, hc *core.HeaderChain, dl *Downloader) *FakePeer {
    return &FakePeer{id: id, db: db, hc: hc, dl: dl}
}

// Head implements downloader.Peer, returning the current head hash and number
// of the best known header.
func (p *FakePeer) Head() (common.Hash, *big.Int) {
    header := p.hc.CurrentHeader()
    return header.Hash(), header.Number
}

// RequestHeadersByHash implements downloader.Peer, returning a batch of headers
// defined by the origin hash and the associated query parameters.
func (p *FakePeer) RequestHeadersByHash(hash common.Hash, amount int, skip int, reverse bool) error {
    var (
        headers []*types.Header
        unknown bool
    )
    for !unknown && len(headers) < amount {
        origin := p.hc.GetHeaderByHash(hash)
        if origin == nil {
            break
        }
        number := origin.Number.Uint64()
        headers = append(headers, origin)
        if reverse {
            for i := 0; i <= skip; i++ {
                if header := p.hc.GetHeader(hash, number); header != nil {
                    hash = header.ParentHash
                    number--
                } else {
                    unknown = true
                    break
                }
            }
        } else {
            var (
                current = origin.Number.Uint64()
                next    = current + uint64(skip) + 1
            )
            if header := p.hc.GetHeaderByNumber(next); header != nil {
                if p.hc.GetBlockHashesFromHash(header.Hash(), uint64(skip+1))[skip] == hash {
                    hash = header.Hash()
                } else {
                    unknown = true
                }
            } else {
                unknown = true
            }
        }
    }
    p.dl.DeliverHeaders(p.id, headers)
    return nil
}

// RequestHeadersByNumber implements downloader.Peer, returning a batch of headers
// defined by the origin number and the associated query parameters.
func (p *FakePeer) RequestHeadersByNumber(number uint64, amount int, skip int, reverse bool) error {
    var (
        headers []*types.Header
        unknown bool
    )
    for !unknown && len(headers) < amount {
        origin := p.hc.GetHeaderByNumber(number)
        if origin == nil {
            break
        }
        if reverse {
            if number >= uint64(skip+1) {
                number -= uint64(skip + 1)
            } else {
                unknown = true
            }
        } else {
            number += uint64(skip + 1)
        }
        headers = append(headers, origin)
    }
    p.dl.DeliverHeaders(p.id, headers)
    return nil
}

// RequestBodies implements downloader.Peer, returning a batch of block bodies
// corresponding to the specified block hashes.
func (p *FakePeer) RequestBodies(hashes []common.Hash) error {
    var (
        txs    [][]*types.Transaction
        uncles [][]*types.Header
    )
    for _, hash := range hashes {
        block := rawdb.ReadBlock(p.db, hash, *p.hc.GetBlockNumber(hash))

        txs = append(txs, block.Transactions())
        uncles = append(uncles, block.Uncles())
    }
    p.dl.DeliverBodies(p.id, txs, uncles)
    return nil
}

// RequestReceipts implements downloader.Peer, returning a batch of transaction
// receipts corresponding to the specified block hashes.
func (p *FakePeer) RequestReceipts(hashes []common.Hash) error {
    var receipts [][]*types.Receipt
    for _, hash := range hashes {
        receipts = append(receipts, rawdb.ReadReceipts(p.db, hash, *p.hc.GetBlockNumber(hash)))
    }
    p.dl.DeliverReceipts(p.id, receipts)
    return nil
}

// RequestNodeData implements downloader.Peer, returning a batch of state trie
// nodes corresponding to the specified trie hashes.
func (p *FakePeer) RequestNodeData(hashes []common.Hash) error {
    var data [][]byte
    for _, hash := range hashes {
        if entry, err := p.db.Get(hash.Bytes()); err == nil {
            data = append(data, entry)
        }
    }
    p.dl.DeliverNodeData(p.id, data)
    return nil
}