1 files changed, 348 insertions, 0 deletions
diff --git a/eth/filters/filter.go b/eth/filters/filter.go
new file mode 100644
index 0000000..fa3d985
--- /dev/null
+++ b/eth/filters/filter.go
@@ -0,0 +1,348 @@
+// 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"
+	"errors"
+	"math/big"
+
+	"github.com/ava-labs/coreth/rpc"
+	"github.com/ava-labs/go-ethereum/common"
+	"github.com/ava-labs/go-ethereum/core"
+	"github.com/ava-labs/go-ethereum/core/bloombits"
+	"github.com/ava-labs/go-ethereum/core/types"
+	"github.com/ava-labs/go-ethereum/ethdb"
+	"github.com/ava-labs/go-ethereum/event"
+)
+
+type Backend interface {
+	ChainDb() ethdb.Database
+	EventMux() *event.TypeMux
+	HeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*types.Header, error)
+	HeaderByHash(ctx context.Context, blockHash common.Hash) (*types.Header, error)
+	GetReceipts(ctx context.Context, blockHash common.Hash) (types.Receipts, error)
+	GetLogs(ctx context.Context, blockHash common.Hash) ([][]*types.Log, error)
+
+	SubscribeNewTxsEvent(chan<- core.NewTxsEvent) event.Subscription
+	SubscribeChainEvent(ch chan<- core.ChainEvent) event.Subscription
+	SubscribeRemovedLogsEvent(ch chan<- core.RemovedLogsEvent) event.Subscription
+	SubscribeLogsEvent(ch chan<- []*types.Log) event.Subscription
+
+	BloomStatus() (uint64, uint64)
+	ServiceFilter(ctx context.Context, session *bloombits.MatcherSession)
+}
+
+// Filter can be used to retrieve and filter logs.
+type Filter struct {
+	backend Backend
+
+	db        ethdb.Database
+	addresses []common.Address
+	topics    [][]common.Hash
+
+	block      common.Hash // Block hash if filtering a single block
+	begin, end int64       // Range interval if filtering multiple blocks
+
+	matcher *bloombits.Matcher
+}
+
+// NewRangeFilter creates a new filter which uses a bloom filter on blocks to
+// figure out whether a particular block is interesting or not.
+func NewRangeFilter(backend Backend, begin, end int64, addresses []common.Address, topics [][]common.Hash) *Filter {
+	// Flatten the address and topic filter clauses into a single bloombits filter
+	// system. Since the bloombits are not positional, nil topics are permitted,
+	// which get flattened into a nil byte slice.
+	var filters [][][]byte
+	if len(addresses) > 0 {
+		filter := make([][]byte, len(addresses))
+		for i, address := range addresses {
+			filter[i] = address.Bytes()
+		}
+		filters = append(filters, filter)
+	}
+	for _, topicList := range topics {
+		filter := make([][]byte, len(topicList))
+		for i, topic := range topicList {
+			filter[i] = topic.Bytes()
+		}
+		filters = append(filters, filter)
+	}
+	size, _ := backend.BloomStatus()
+
+	// Create a generic filter and convert it into a range filter
+	filter := newFilter(backend, addresses, topics)
+
+	filter.matcher = bloombits.NewMatcher(size, filters)
+	filter.begin = begin
+	filter.end = end
+
+	return filter
+}
+
+// NewBlockFilter creates a new filter which directly inspects the contents of
+// a block to figure out whether it is interesting or not.
+func NewBlockFilter(backend Backend, block common.Hash, addresses []common.Address, topics [][]common.Hash) *Filter {
+	// Create a generic filter and convert it into a block filter
+	filter := newFilter(backend, addresses, topics)
+	filter.block = block
+	return filter
+}
+
+// newFilter creates a generic filter that can either filter based on a block hash,
+// or based on range queries. The search criteria needs to be explicitly set.
+func newFilter(backend Backend, addresses []common.Address, topics [][]common.Hash) *Filter {
+	return &Filter{
+		backend:   backend,
+		addresses: addresses,
+		topics:    topics,
+		db:        backend.ChainDb(),
+	}
+}
+
+// Logs searches the blockchain for matching log entries, returning all from the
+// first block that contains matches, updating the start of the filter accordingly.
+func (f *Filter) Logs(ctx context.Context) ([]*types.Log, error) {
+	// If we're doing singleton block filtering, execute and return
+	if f.block != (common.Hash{}) {
+		header, err := f.backend.HeaderByHash(ctx, f.block)
+		if err != nil {
+			return nil, err
+		}
+		if header == nil {
+			return nil, errors.New("unknown block")
+		}
+		return f.blockLogs(ctx, header)
+	}
+	// Figure out the limits of the filter range
+	header, _ := f.backend.HeaderByNumber(ctx, rpc.LatestBlockNumber)
+	if header == nil {
+		return nil, nil
+	}
+	head := header.Number.Uint64()
+
+	if f.begin == -1 {
+		f.begin = int64(head)
+	}
+	end := uint64(f.end)
+	if f.end == -1 {
+		end = head
+	}
+	// Gather all indexed logs, and finish with non indexed ones
+	var (
+		logs []*types.Log
+		err  error
+	)
+	size, sections := f.backend.BloomStatus()
+	if indexed := sections * size; indexed > uint64(f.begin) {
+		if indexed > end {
+			logs, err = f.indexedLogs(ctx, end)
+		} else {
+			logs, err = f.indexedLogs(ctx, indexed-1)
+		}
+		if err != nil {
+			return logs, err
+		}
+	}
+	rest, err := f.unindexedLogs(ctx, end)
+	logs = append(logs, rest...)
+	return logs, err
+}
+
+// indexedLogs returns the logs matching the filter criteria based on the bloom
+// bits indexed available locally or via the network.
+func (f *Filter) indexedLogs(ctx context.Context, end uint64) ([]*types.Log, error) {
+	// Create a matcher session and request servicing from the backend
+	matches := make(chan uint64, 64)
+
+	session, err := f.matcher.Start(ctx, uint64(f.begin), end, matches)
+	if err != nil {
+		return nil, err
+	}
+	defer session.Close()
+
+	f.backend.ServiceFilter(ctx, session)
+
+	// Iterate over the matches until exhausted or context closed
+	var logs []*types.Log
+
+	for {
+		select {
+		case number, ok := <-matches:
+			// Abort if all matches have been fulfilled
+			if !ok {
+				err := session.Error()
+				if err == nil {
+					f.begin = int64(end) + 1
+				}
+				return logs, err
+			}
+			f.begin = int64(number) + 1
+
+			// Retrieve the suggested block and pull any truly matching logs
+			header, err := f.backend.HeaderByNumber(ctx, rpc.BlockNumber(number))
+			if header == nil || err != nil {
+				return logs, err
+			}
+			found, err := f.checkMatches(ctx, header)
+			if err != nil {
+				return logs, err
+			}
+			logs = append(logs, found...)
+
+		case <-ctx.Done():
+			return logs, ctx.Err()
+		}
+	}
+}
+
+// indexedLogs returns the logs matching the filter criteria based on raw block
+// iteration and bloom matching.
+func (f *Filter) unindexedLogs(ctx context.Context, end uint64) ([]*types.Log, error) {
+	var logs []*types.Log
+
+	for ; f.begin <= int64(end); f.begin++ {
+		header, err := f.backend.HeaderByNumber(ctx, rpc.BlockNumber(f.begin))
+		if header == nil || err != nil {
+			return logs, err
+		}
+		found, err := f.blockLogs(ctx, header)
+		if err != nil {
+			return logs, err
+		}
+		logs = append(logs, found...)
+	}
+	return logs, nil
+}
+
+// blockLogs returns the logs matching the filter criteria within a single block.
+func (f *Filter) blockLogs(ctx context.Context, header *types.Header) (logs []*types.Log, err error) {
+	if bloomFilter(header.Bloom, f.addresses, f.topics) {
+		found, err := f.checkMatches(ctx, header)
+		if err != nil {
+			return logs, err
+		}
+		logs = append(logs, found...)
+	}
+	return logs, nil
+}
+
+// checkMatches checks if the receipts belonging to the given header contain any log events that
+// match the filter criteria. This function is called when the bloom filter signals a potential match.
+func (f *Filter) checkMatches(ctx context.Context, header *types.Header) (logs []*types.Log, err error) {
+	// Get the logs of the block
+	logsList, err := f.backend.GetLogs(ctx, header.Hash())
+	if err != nil {
+		return nil, err
+	}
+	var unfiltered []*types.Log
+	for _, logs := range logsList {
+		unfiltered = append(unfiltered, logs...)
+	}
+	logs = filterLogs(unfiltered, nil, nil, f.addresses, f.topics)
+	if len(logs) > 0 {
+		// We have matching logs, check if we need to resolve full logs via the light client
+		if logs[0].TxHash == (common.Hash{}) {
+			receipts, err := f.backend.GetReceipts(ctx, header.Hash())
+			if err != nil {
+				return nil, err
+			}
+			unfiltered = unfiltered[:0]
+			for _, receipt := range receipts {
+				unfiltered = append(unfiltered, receipt.Logs...)
+			}
+			logs = filterLogs(unfiltered, nil, nil, f.addresses, f.topics)
+		}
+		return logs, nil
+	}
+	return nil, 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
+		}
+		// 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, sub := range topics {
+			match := len(sub) == 0 // empty rule set == wildcard
+			for _, topic := range sub {
+				if log.Topics[i] == topic {
+					match = true
+					break
+				}
+			}
+			if !match {
+				continue Logs
+			}
+		}
+		ret = append(ret, log)
+	}
+	return ret
+}
+
+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 {
+		included := len(sub) == 0 // empty rule set == wildcard
+		for _, topic := range sub {
+			if types.BloomLookup(bloom, topic) {
+				included = true
+				break
+			}
+		}
+		if !included {
+			return false
+		}
+	}
+	return true
+}