gossip/filters/api.go
// Copyright 2015 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"
"encoding/json"
"errors"
"fmt"
"math/big"
"sync"
"time"
ethereum "github.com/ethereum/go-ethereum"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/rpc"
)
var (
deadline = 5 * time.Minute // consider a filter inactive if it has not been polled for within deadline
)
// filter is a helper struct that holds meta information over the filter type
// and associated subscription in the event system.
type filter struct {
typ Type
deadline *time.Timer // filter is inactiv when deadline triggers
hashes []common.Hash
crit FilterCriteria
logs []*types.Log
s *Subscription // associated subscription in event system
}
// PublicFilterAPI offers support to create and manage filters. This will allow external clients to retrieve various
// information related to the Ethereum protocol such als blocks, transactions and logs.
type PublicFilterAPI struct {
backend Backend
chainDb ethdb.Database
events *EventSystem
filtersMu sync.Mutex
filters map[rpc.ID]*filter
}
// NewPublicFilterAPI returns a new PublicFilterAPI instance.
func NewPublicFilterAPI(backend Backend) *PublicFilterAPI {
api := &PublicFilterAPI{
backend: backend,
chainDb: backend.ChainDb(),
events: NewEventSystem(backend),
filters: make(map[rpc.ID]*filter),
}
go api.timeoutLoop()
return api
}
// timeoutLoop runs every 5 minutes and deletes filters that have not been recently used.
// Tt is started when the api is created.
func (api *PublicFilterAPI) timeoutLoop() {
ticker := time.NewTicker(5 * time.Minute)
for {
<-ticker.C
api.filtersMu.Lock()
for id, f := range api.filters {
select {
case <-f.deadline.C:
f.s.Unsubscribe()
delete(api.filters, id)
default:
continue
}
}
api.filtersMu.Unlock()
}
}
// NewPendingTransactionFilter creates a filter that fetches pending transaction hashes
// as transactions enter the pending state.
//
// It is part of the filter package because this filter can be used through the
// `eth_getFilterChanges` polling method that is also used for log filters.
//
// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_newpendingtransactionfilter
func (api *PublicFilterAPI) NewPendingTransactionFilter() rpc.ID {
var (
pendingTxs = make(chan []common.Hash)
pendingTxSub = api.events.SubscribePendingTxs(pendingTxs)
)
api.filtersMu.Lock()
api.filters[pendingTxSub.ID] = &filter{typ: PendingTransactionsSubscription, deadline: time.NewTimer(deadline), hashes: make([]common.Hash, 0), s: pendingTxSub}
api.filtersMu.Unlock()
go func() {
for {
select {
case ph := <-pendingTxs:
api.filtersMu.Lock()
if f, found := api.filters[pendingTxSub.ID]; found {
f.hashes = append(f.hashes, ph...)
}
api.filtersMu.Unlock()
case <-pendingTxSub.Err():
api.filtersMu.Lock()
delete(api.filters, pendingTxSub.ID)
api.filtersMu.Unlock()
return
}
}
}()
return pendingTxSub.ID
}
// NewPendingTransactions creates a subscription that is triggered each time a transaction
// enters the transaction pool and was signed from one of the transactions this nodes manages.
func (api *PublicFilterAPI) NewPendingTransactions(ctx context.Context) (*rpc.Subscription, error) {
notifier, supported := rpc.NotifierFromContext(ctx)
if !supported {
return &rpc.Subscription{}, rpc.ErrNotificationsUnsupported
}
rpcSub := notifier.CreateSubscription()
go func() {
txHashes := make(chan []common.Hash, 128)
pendingTxSub := api.events.SubscribePendingTxs(txHashes)
for {
select {
case hashes := <-txHashes:
// To keep the original behaviour, send a single tx hash in one notification.
// TODO(rjl493456442) Send a batch of tx hashes in one notification
for _, h := range hashes {
_ = notifier.Notify(rpcSub.ID, h)
}
case <-rpcSub.Err():
pendingTxSub.Unsubscribe()
return
case <-notifier.Closed():
pendingTxSub.Unsubscribe()
return
}
}
}()
return rpcSub, nil
}
// NewBlockFilter creates a filter that fetches blocks that are imported into the chain.
// It is part of the filter package since polling goes with eth_getFilterChanges.
//
// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_newblockfilter
func (api *PublicFilterAPI) NewBlockFilter() rpc.ID {
var (
headers = make(chan *types.Header)
headerSub = api.events.SubscribeNewHeads(headers)
)
api.filtersMu.Lock()
api.filters[headerSub.ID] = &filter{typ: BlocksSubscription, deadline: time.NewTimer(deadline), hashes: make([]common.Hash, 0), s: headerSub}
api.filtersMu.Unlock()
go func() {
for {
select {
case h := <-headers:
api.filtersMu.Lock()
if f, found := api.filters[headerSub.ID]; found {
f.hashes = append(f.hashes, h.Hash())
}
api.filtersMu.Unlock()
case <-headerSub.Err():
api.filtersMu.Lock()
delete(api.filters, headerSub.ID)
api.filtersMu.Unlock()
return
}
}
}()
return headerSub.ID
}
// NewHeads send a notification each time a new (header) block is appended to the chain.
func (api *PublicFilterAPI) NewHeads(ctx context.Context) (*rpc.Subscription, error) {
notifier, supported := rpc.NotifierFromContext(ctx)
if !supported {
return &rpc.Subscription{}, rpc.ErrNotificationsUnsupported
}
rpcSub := notifier.CreateSubscription()
go func() {
headers := make(chan *types.Header)
headersSub := api.events.SubscribeNewHeads(headers)
for {
select {
case h := <-headers:
_ = notifier.Notify(rpcSub.ID, h)
case <-rpcSub.Err():
headersSub.Unsubscribe()
return
case <-notifier.Closed():
headersSub.Unsubscribe()
return
}
}
}()
return rpcSub, nil
}
// Logs creates a subscription that fires for all new log that match the given filter criteria.
func (api *PublicFilterAPI) Logs(ctx context.Context, crit FilterCriteria) (*rpc.Subscription, error) {
notifier, supported := rpc.NotifierFromContext(ctx)
if !supported {
return &rpc.Subscription{}, rpc.ErrNotificationsUnsupported
}
var (
rpcSub = notifier.CreateSubscription()
matchedLogs = make(chan []*types.Log)
)
logsSub, err := api.events.SubscribeLogs(ethereum.FilterQuery(crit), matchedLogs)
if err != nil {
return nil, err
}
go func() {
for {
select {
case logs := <-matchedLogs:
for _, log := range logs {
_ = notifier.Notify(rpcSub.ID, &log)
}
case <-rpcSub.Err(): // client send an unsubscribe request
logsSub.Unsubscribe()
return
case <-notifier.Closed(): // connection dropped
logsSub.Unsubscribe()
return
}
}
}()
return rpcSub, nil
}
// FilterCriteria represents a request to create a new filter.
// Same as ethereum.FilterQuery but with UnmarshalJSON() method.
type FilterCriteria ethereum.FilterQuery
// NewFilter creates a new filter and returns the filter id. It can be
// used to retrieve logs when the state changes. This method cannot be
// used to fetch logs that are already stored in the state.
//
// Default criteria for the from and to block are "latest".
// Using "latest" as block number will return logs for mined blocks.
// Using "pending" as block number returns logs for not yet mined (pending) blocks.
// In case logs are removed (chain reorg) previously returned logs are returned
// again but with the removed property set to true.
//
// In case "fromBlock" > "toBlock" an error is returned.
//
// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_newfilter
func (api *PublicFilterAPI) NewFilter(crit FilterCriteria) (rpc.ID, error) {
logs := make(chan []*types.Log)
logsSub, err := api.events.SubscribeLogs(ethereum.FilterQuery(crit), logs)
if err != nil {
return rpc.ID(""), err
}
api.filtersMu.Lock()
api.filters[logsSub.ID] = &filter{typ: LogsSubscription, crit: crit, deadline: time.NewTimer(deadline), logs: make([]*types.Log, 0), s: logsSub}
api.filtersMu.Unlock()
go func() {
for {
select {
case l := <-logs:
api.filtersMu.Lock()
if f, found := api.filters[logsSub.ID]; found {
f.logs = append(f.logs, l...)
}
api.filtersMu.Unlock()
case <-logsSub.Err():
api.filtersMu.Lock()
delete(api.filters, logsSub.ID)
api.filtersMu.Unlock()
return
}
}
}()
return logsSub.ID, nil
}
// GetLogs returns logs matching the given argument that are stored within the state.
//
// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_getlogs
func (api *PublicFilterAPI) GetLogs(ctx context.Context, crit FilterCriteria) ([]*types.Log, error) {
var filter *Filter
if crit.BlockHash != nil {
// Block filter requested, construct a single-shot filter
filter = NewBlockFilter(api.backend, *crit.BlockHash, crit.Addresses, crit.Topics)
} else {
// Convert the RPC block numbers into internal representations
begin := rpc.LatestBlockNumber.Int64()
if crit.FromBlock != nil {
begin = crit.FromBlock.Int64()
}
end := rpc.LatestBlockNumber.Int64()
if crit.ToBlock != nil {
end = crit.ToBlock.Int64()
}
// Construct the range filter
filter = NewRangeFilter(api.backend, begin, end, crit.Addresses, crit.Topics)
}
// Run the filter and return all the logs
logs, err := filter.Logs(ctx)
if err != nil {
return nil, err
}
return returnLogs(logs), err
}
// UninstallFilter removes the filter with the given filter id.
//
// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_uninstallfilter
func (api *PublicFilterAPI) UninstallFilter(id rpc.ID) bool {
api.filtersMu.Lock()
f, found := api.filters[id]
if found {
delete(api.filters, id)
}
api.filtersMu.Unlock()
if found {
f.s.Unsubscribe()
}
return found
}
// GetFilterLogs returns the logs for the filter with the given id.
// If the filter could not be found an empty array of logs is returned.
//
// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_getfilterlogs
func (api *PublicFilterAPI) GetFilterLogs(ctx context.Context, id rpc.ID) ([]*types.Log, error) {
api.filtersMu.Lock()
f, found := api.filters[id]
api.filtersMu.Unlock()
if !found || f.typ != LogsSubscription {
return nil, fmt.Errorf("filter not found")
}
var filter *Filter
if f.crit.BlockHash != nil {
// Block filter requested, construct a single-shot filter
filter = NewBlockFilter(api.backend, *f.crit.BlockHash, f.crit.Addresses, f.crit.Topics)
} else {
// Convert the RPC block numbers into internal representations
begin := rpc.LatestBlockNumber.Int64()
if f.crit.FromBlock != nil {
begin = f.crit.FromBlock.Int64()
}
end := rpc.LatestBlockNumber.Int64()
if f.crit.ToBlock != nil {
end = f.crit.ToBlock.Int64()
}
// Construct the range filter
filter = NewRangeFilter(api.backend, begin, end, f.crit.Addresses, f.crit.Topics)
}
// Run the filter and return all the logs
logs, err := filter.Logs(ctx)
if err != nil {
return nil, err
}
return returnLogs(logs), nil
}
// GetFilterChanges returns the logs for the filter with the given id since
// last time it was called. This can be used for polling.
//
// For pending transaction and block filters the result is []common.Hash.
// (pending)Log filters return []Log.
//
// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_getfilterchanges
func (api *PublicFilterAPI) GetFilterChanges(id rpc.ID) (interface{}, error) {
api.filtersMu.Lock()
defer api.filtersMu.Unlock()
if f, found := api.filters[id]; found {
if !f.deadline.Stop() {
// timer expired but filter is not yet removed in timeout loop
// receive timer value and reset timer
<-f.deadline.C
}
f.deadline.Reset(deadline)
switch f.typ {
case PendingTransactionsSubscription, BlocksSubscription:
hashes := f.hashes
f.hashes = nil
return returnHashes(hashes), nil
case LogsSubscription:
logs := f.logs
f.logs = nil
return returnLogs(logs), nil
}
}
return []interface{}{}, fmt.Errorf("filter not found")
}
// returnHashes is a helper that will return an empty hash array case the given hash array is nil,
// otherwise the given hashes array is returned.
func returnHashes(hashes []common.Hash) []common.Hash {
if hashes == nil {
return []common.Hash{}
}
return hashes
}
// returnLogs is a helper that will return an empty log array in case the given logs array is nil,
// otherwise the given logs array is returned.
func returnLogs(logs []*types.Log) []*types.Log {
if logs == nil {
return []*types.Log{}
}
return logs
}
// UnmarshalJSON sets *args fields with given data.
func (args *FilterCriteria) UnmarshalJSON(data []byte) error {
type input struct {
BlockHash *common.Hash `json:"blockHash"`
FromBlock *rpc.BlockNumber `json:"fromBlock"`
ToBlock *rpc.BlockNumber `json:"toBlock"`
Addresses interface{} `json:"address"`
Topics []interface{} `json:"topics"`
}
var raw input
if err := json.Unmarshal(data, &raw); err != nil {
return err
}
if raw.BlockHash != nil {
if raw.FromBlock != nil || raw.ToBlock != nil {
// BlockHash is mutually exclusive with FromBlock/ToBlock criteria
return fmt.Errorf("cannot specify both BlockHash and FromBlock/ToBlock, choose one or the other")
}
args.BlockHash = raw.BlockHash
} else {
if raw.FromBlock != nil {
args.FromBlock = big.NewInt(raw.FromBlock.Int64())
}
if raw.ToBlock != nil {
args.ToBlock = big.NewInt(raw.ToBlock.Int64())
}
}
args.Addresses = []common.Address{}
if raw.Addresses != nil {
// raw.Address can contain a single address or an array of addresses
switch rawAddr := raw.Addresses.(type) {
case []interface{}:
for i, addr := range rawAddr {
if strAddr, ok := addr.(string); ok {
addr, err := decodeAddress(strAddr)
if err != nil {
return fmt.Errorf("invalid address at index %d: %v", i, err)
}
args.Addresses = append(args.Addresses, addr)
} else {
return fmt.Errorf("non-string address at index %d", i)
}
}
case string:
addr, err := decodeAddress(rawAddr)
if err != nil {
return fmt.Errorf("invalid address: %v", err)
}
args.Addresses = []common.Address{addr}
default:
return errors.New("invalid addresses in query")
}
}
// topics is an array consisting of strings and/or arrays of strings.
// JSON null values are converted to common.Hash{} and ignored by the filter manager.
if len(raw.Topics) > 0 {
args.Topics = make([][]common.Hash, len(raw.Topics))
for i, t := range raw.Topics {
switch topic := t.(type) {
case nil:
// ignore topic when matching logs
case string:
// match specific topic
top, err := decodeTopic(topic)
if err != nil {
return err
}
args.Topics[i] = []common.Hash{top}
case []interface{}:
// or case e.g. [null, "topic0", "topic1"]
for _, rawTopic := range topic {
if rawTopic == nil {
// null component, match all
args.Topics[i] = nil
break
}
if topic, ok := rawTopic.(string); ok {
parsed, err := decodeTopic(topic)
if err != nil {
return err
}
args.Topics[i] = append(args.Topics[i], parsed)
} else {
return fmt.Errorf("invalid topic(s)")
}
}
default:
return fmt.Errorf("invalid topic(s)")
}
}
}
return nil
}
func decodeAddress(s string) (common.Address, error) {
b, err := hexutil.Decode(s)
if err == nil && len(b) != common.AddressLength {
err = fmt.Errorf("hex has invalid length %d after decoding; expected %d for address", len(b), common.AddressLength)
}
return common.BytesToAddress(b), err
}
func decodeTopic(s string) (common.Hash, error) {
b, err := hexutil.Decode(s)
if err == nil && len(b) != common.HashLength {
err = fmt.Errorf("hex has invalid length %d after decoding; expected %d for topic", len(b), common.HashLength)
}
return common.BytesToHash(b), err
}