// 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 (
"math"
"time"
"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"
)
// Filter can be used to retrieve and filter logs
type Filter struct {
created time.Time
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.
func New(db ethdb.Database) *Filter {
return &Filter{db: db}
}
// 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
}
// Run filters logs with the current parameters set
func (f *Filter) Find() []Log {
latestHash := core.GetHeadBlockHash(f.db)
latestBlock := core.GetBlock(f.db, latestHash, core.GetBlockNumber(f.db, latestHash))
if latestBlock == nil {
return []Log{}
}
var beginBlockNo uint64 = uint64(f.begin)
if f.begin == -1 {
beginBlockNo = latestBlock.NumberU64()
}
endBlockNo := uint64(f.end)
if f.end == -1 {
endBlockNo = latestBlock.NumberU64()
}
// 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 len(f.addresses) == 0 {
return f.getLogs(beginBlockNo, endBlockNo)
}
return f.mipFind(beginBlockNo, endBlockNo, 0)
}
func (f *Filter) mipFind(start, end uint64, depth int) (logs []Log) {
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)
for _, addr := range f.addresses {
if bloom.TestBytes(addr[:]) {
// 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) {
logs = append(logs, f.getLogs(start, end)...)
} else {
logs = append(logs, f.mipFind(start, end, depth+1)...)
}
// break so we don't check the same range for each
// possible address. Checks on multiple addresses
// are handled further down the stack.
break
}
}
}
return logs
}
func (f *Filter) getLogs(start, end uint64) (logs []Log) {
var block *types.Block
for i := start; i <= end; i++ {
hash := core.GetCanonicalHash(f.db, i)
if hash != (common.Hash{}) {
block = core.GetBlock(f.db, hash, i)
} else { // block not found
return logs
}
if block == nil { // block not found/written
return logs
}
// Use bloom filtering to see if this block is interesting given the
// current parameters
if f.bloomFilter(block) {
// Get the logs of the block
var (
receipts = core.GetBlockReceipts(f.db, block.Hash(), i)
unfiltered []Log
)
for _, receipt := range receipts {
rl := make([]Log, len(receipt.Logs))
for i, l := range receipt.Logs {
rl[i] = Log{l, false}
}
unfiltered = append(unfiltered, rl...)
}
logs = append(logs, filterLogs(unfiltered, f.addresses, f.topics)...)
}
}
return logs
}
func includes(addresses []common.Address, a common.Address) bool {
for _, addr := range addresses {
if addr == a {
return true
}
}
return false
}
func filterLogs(logs []Log, addresses []common.Address, topics [][]common.Hash) []Log {
var ret []Log
// Filter the logs for interesting stuff
Logs:
for _, log := range logs {
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(block *types.Block) bool {
if len(f.addresses) > 0 {
var included bool
for _, addr := range f.addresses {
if types.BloomLookup(block.Bloom(), addr) {
included = true
break
}
}
if !included {
return false
}
}
for _, sub := range f.topics {
var included bool
for _, topic := range sub {
if (topic == common.Hash{}) || types.BloomLookup(block.Bloom(), topic) {
included = true
break
}
}
if !included {
return false
}
}
return true
}