// Copyright 2014 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 filters
import (
"context"
"math"
"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/ethdb"
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/rpc"
)
type Backend interface {
ChainDb() ethdb.Database
EventMux() *event.TypeMux
HeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*types.Header, error)
GetReceipts(ctx context.Context, blockHash common.Hash) (types.Receipts, error)
SubscribeTxPreEvent(chan<- core.TxPreEvent) event.Subscription
SubscribeChainEvent(ch chan<- core.ChainEvent) event.Subscription
SubscribeRemovedLogsEvent(ch chan<- core.RemovedLogsEvent) event.Subscription
SubscribeLogsEvent(ch chan<- []*types.Log) event.Subscription
}
// Filter can be used to retrieve and filter logs.
type Filter struct {
backend Backend
useMipMap bool
db ethdb.Database
begin, end int64
addresses []common.Address
topics [][]common.Hash
}
// New creates a new filter which uses a bloom filter on blocks to figure out whether
// a particular block is interesting or not.
// MipMaps allow past blocks to be searched much more efficiently, but are not available
// to light clients.
func New(backend Backend, useMipMap bool) *Filter {
return &Filter{
backend: backend,
useMipMap: useMipMap,
db: backend.ChainDb(),
}
}
// SetBeginBlock sets the earliest block for filtering.
// -1 = latest block (i.e., the current block)
// hash = particular hash from-to
func (f *Filter) SetBeginBlock(begin int64) {
f.begin = begin
}
// SetEndBlock sets the latest block for filtering.
func (f *Filter) SetEndBlock(end int64) {
f.end = end
}
// SetAddresses matches only logs that are generated from addresses that are included
// in the given addresses.
func (f *Filter) SetAddresses(addr []common.Address) {
f.addresses = addr
}
// SetTopics matches only logs that have topics matching the given topics.
func (f *Filter) SetTopics(topics [][]common.Hash) {
f.topics = topics
}
// FindOnce searches the blockchain for matching log entries, returning
// all matching entries from the first block that contains matches,
// updating the start point of the filter accordingly. If no results are
// found, a nil slice is returned.
func (f *Filter) FindOnce(ctx context.Context) ([]*types.Log, error) {
head, _ := f.backend.HeaderByNumber(ctx, rpc.LatestBlockNumber)
if head == nil {
return nil, nil
}
headBlockNumber := head.Number.Uint64()
var beginBlockNo uint64 = uint64(f.begin)
if f.begin == -1 {
beginBlockNo = headBlockNumber
}
var endBlockNo uint64 = uint64(f.end)
if f.end == -1 {
endBlockNo = headBlockNumber
}
// if no addresses are present we can't make use of fast search which
// uses the mipmap bloom filters to check for fast inclusion and uses
// higher range probability in order to ensure at least a false positive
if !f.useMipMap || len(f.addresses) == 0 {
logs, blockNumber, err := f.getLogs(ctx, beginBlockNo, endBlockNo)
f.begin = int64(blockNumber + 1)
return logs, err
}
logs, blockNumber := f.mipFind(beginBlockNo, endBlockNo, 0)
f.begin = int64(blockNumber + 1)
return logs, nil
}
// Run filters logs with the current parameters set
func (f *Filter) Find(ctx context.Context) (logs []*types.Log, err error) {
for {
newLogs, err := f.FindOnce(ctx)
if len(newLogs) == 0 || err != nil {
return logs, err
}
logs = append(logs, newLogs...)
}
}
func (f *Filter) mipFind(start, end uint64, depth int) (logs []*types.Log, blockNumber uint64) {
level := core.MIPMapLevels[depth]
// normalise numerator so we can work in level specific batches and
// work with the proper range checks
for num := start / level * level; num <= end; num += level {
// find addresses in bloom filters
bloom := core.GetMipmapBloom(f.db, num, level)
// Don't bother checking the first time through the loop - we're probably picking
// up where a previous run left off.
first := true
for _, addr := range f.addresses {
if first || bloom.TestBytes(addr[:]) {
first = false
// range check normalised values and make sure that
// we're resolving the correct range instead of the
// normalised values.
start := uint64(math.Max(float64(num), float64(start)))
end := uint64(math.Min(float64(num+level-1), float64(end)))
if depth+1 == len(core.MIPMapLevels) {
l, blockNumber, _ := f.getLogs(context.Background(), start, end)
if len(l) > 0 {
return l, blockNumber
}
} else {
l, blockNumber := f.mipFind(start, end, depth+1)
if len(l) > 0 {
return l, blockNumber
}
}
}
}
}
return nil, end
}
func (f *Filter) getLogs(ctx context.Context, start, end uint64) (logs []*types.Log, blockNumber uint64, err error) {
for i := start; i <= end; i++ {
blockNumber := rpc.BlockNumber(i)
header, err := f.backend.HeaderByNumber(ctx, blockNumber)
if header == nil || err != nil {
return logs, end, err
}
// Use bloom filtering to see if this block is interesting given the
// current parameters
if f.bloomFilter(header.Bloom) {
// Get the logs of the block
receipts, err := f.backend.GetReceipts(ctx, header.Hash())
if err != nil {
return nil, end, err
}
var unfiltered []*types.Log
for _, receipt := range receipts {
unfiltered = append(unfiltered, ([]*types.Log)(receipt.Logs)...)
}
logs = filterLogs(unfiltered, nil, nil, f.addresses, f.topics)
if len(logs) > 0 {
return logs, uint64(blockNumber), nil
}
}
}
return logs, end, nil
}
func includes(addresses []common.Address, a common.Address) bool {
for _, addr := range addresses {
if addr == a {
return true
}
}
return false
}
// filterLogs creates a slice of logs matching the given criteria.
func filterLogs(logs []*types.Log, fromBlock, toBlock *big.Int, addresses []common.Address, topics [][]common.Hash) []*types.Log {
var ret []*types.Log
Logs:
for _, log := range logs {
if fromBlock != nil && fromBlock.Int64() >= 0 && fromBlock.Uint64() > log.BlockNumber {
continue
}
if toBlock != nil && toBlock.Int64() >= 0 && toBlock.Uint64() < log.BlockNumber {
continue
}
if len(addresses) > 0 && !includes(addresses, log.Address) {
continue
}
logTopics := make([]common.Hash, len(topics))
copy(logTopics, log.Topics)
// If the to filtered topics is greater than the amount of topics in logs, skip.
if len(topics) > len(log.Topics) {
continue Logs
}
for i, topics := range topics {
var match bool
for _, topic := range topics {
// common.Hash{} is a match all (wildcard)
if (topic == common.Hash{}) || log.Topics[i] == topic {
match = true
break
}
}
if !match {
continue Logs
}
}
ret = append(ret, log)
}
return ret
}
func (f *Filter) bloomFilter(bloom types.Bloom) bool {
return bloomFilter(bloom, f.addresses, f.topics)
}
func bloomFilter(bloom types.Bloom, addresses []common.Address, topics [][]common.Hash) bool {
if len(addresses) > 0 {
var included bool
for _, addr := range addresses {
if types.BloomLookup(bloom, addr) {
included = true
break
}
}
if !included {
return false
}
}
for _, sub := range topics {
var included bool
for _, topic := range sub {
if (topic == common.Hash{}) || types.BloomLookup(bloom, topic) {
included = true
break
}
}
if !included {
return false
}
}
return true
}