path: root/eth/filters/filter.go

// 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(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(block.Bloom(), topic) {
                included = true
                break
            }
        }
        if !included {
            return false
        }
    }

    return true
}