plugeth/miner/miner.go
Martin Holst Swende 1e10489196
miner: don't interrupt mining after successful sync (#21701)
* miner: exit loop when downloader Done or Failed

Following the logic of the comment at the method,
this fixes a regression introduced at 7cf56d6f06
, which would allow external parties to DoS with
blocks, preventing mining progress.

Signed-off-by: meows <b5c6@protonmail.com>

* miner: remove ineff assign (lint)

Signed-off-by: meows <b5c6@protonmail.com>

* miner: update test re downloader events

Signed-off-by: meows <b5c6@protonmail.com>

* Revert "miner: remove ineff assign (lint)"

This reverts commit eaefcd34ab4862ebc936fb8a07578aa2744bc058.

* Revert "miner: exit loop when downloader Done or Failed"

This reverts commit 23abd34265aa246c38fc390bb72572ad6ae9fe3b.

* miner: add test showing imprecise TestMiner

Signed-off-by: meows <b5c6@protonmail.com>

* miner: fix waitForMiningState precision

This helper function would return an affirmation
on the first positive match on a desired bool.

This was imprecise; it return false positives
by not waiting initially for an 'updated' value.

This fix causes TestMiner_2 to fail, which is
expected.

Signed-off-by: meows <b5c6@protonmail.com>

* miner: remove TestMiner_2 demonstrating broken test

This test demonstrated the imprecision of the test
helper function waitForMiningState. This function
has been fixed with 6d365c2851, and this test test
may now be removed.

Signed-off-by: meows <b5c6@protonmail.com>

* miner: fix test regarding downloader event/mining expectations

See comment for logic.

Signed-off-by: meows <b5c6@protonmail.com>

* miner: add test describing expectations for downloader/mining events

We expect that once the downloader emits a DoneEvent,
signaling a successful sync, that subsequent StartEvents
are not longer permitted to stop the miner.

This prevents a security vulnerability where forced syncs via
fake high blocks would stall mining operation.

Signed-off-by: meows <b5c6@protonmail.com>

* miner: use 'canStop' state to fix downloader event handling

- Break downloader event handling into event
separating Done and Failed events. We need to
treat these cases differently since a DoneEvent
should prevent the miner from being stopped on
subsequent downloader Start events.

- Use canStop state to handle the one-off
case when a downloader first succeeds.

Signed-off-by: meows <b5c6@protonmail.com>

* miner: improve comment wording

Signed-off-by: meows <b5c6@protonmail.com>

* miner: start mining on downloader events iff not already mining

Signed-off-by: meows <b5c6@protonmail.com>

* miner: refactor miner update logic w/r/t downloader events

This makes mining pause/start logic regarding downloader
events more explicit. Instead of eternally handling downloader
events after the first done event, the subscription is closed
when downloader events are no longer actionable.

Signed-off-by: meows <b5c6@protonmail.com>

* miner: fix handling downloader events on subcription closed

Signed-off-by: meows <b5c6@protonmail.com>

* miner: (lint:gosimple) use range over chan instead of for/select

Signed-off-by: meows <b5c6@protonmail.com>

* miner: refactor update loop to remove race condition

The go routine handling the downloader events handling
vars in parallel with the parent routine, causing a
race condition.

This change, though ugly, remove the condition while
still allowing the downloader event subscription to be
closed when the miner has no further use for it (ie DoneEvent).

* miner: alternate fix for miner-flaw

Co-authored-by: meows <b5c6@protonmail.com>
2020-10-13 15:12:06 +03:00

223 lines
7.0 KiB
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 miner implements Ethereum block creation and mining.
package miner
import (
"fmt"
"math/big"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/consensus"
"github.com/ethereum/go-ethereum/core"
"github.com/ethereum/go-ethereum/core/state"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/eth/downloader"
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/params"
)
// Backend wraps all methods required for mining.
type Backend interface {
BlockChain() *core.BlockChain
TxPool() *core.TxPool
}
// Config is the configuration parameters of mining.
type Config struct {
Etherbase common.Address `toml:",omitempty"` // Public address for block mining rewards (default = first account)
Notify []string `toml:",omitempty"` // HTTP URL list to be notified of new work packages(only useful in ethash).
ExtraData hexutil.Bytes `toml:",omitempty"` // Block extra data set by the miner
GasFloor uint64 // Target gas floor for mined blocks.
GasCeil uint64 // Target gas ceiling for mined blocks.
GasPrice *big.Int // Minimum gas price for mining a transaction
Recommit time.Duration // The time interval for miner to re-create mining work.
Noverify bool // Disable remote mining solution verification(only useful in ethash).
}
// Miner creates blocks and searches for proof-of-work values.
type Miner struct {
mux *event.TypeMux
worker *worker
coinbase common.Address
eth Backend
engine consensus.Engine
exitCh chan struct{}
startCh chan common.Address
stopCh chan struct{}
}
func New(eth Backend, config *Config, chainConfig *params.ChainConfig, mux *event.TypeMux, engine consensus.Engine, isLocalBlock func(block *types.Block) bool) *Miner {
miner := &Miner{
eth: eth,
mux: mux,
engine: engine,
exitCh: make(chan struct{}),
startCh: make(chan common.Address),
stopCh: make(chan struct{}),
worker: newWorker(config, chainConfig, engine, eth, mux, isLocalBlock, true),
}
go miner.update()
return miner
}
// update keeps track of the downloader events. Please be aware that this is a one shot type of update loop.
// It's entered once and as soon as `Done` or `Failed` has been broadcasted the events are unregistered and
// the loop is exited. This to prevent a major security vuln where external parties can DOS you with blocks
// and halt your mining operation for as long as the DOS continues.
func (miner *Miner) update() {
events := miner.mux.Subscribe(downloader.StartEvent{}, downloader.DoneEvent{}, downloader.FailedEvent{})
defer func() {
if !events.Closed() {
events.Unsubscribe()
}
}()
shouldStart := false
canStart := true
dlEventCh := events.Chan()
for {
select {
case ev := <-dlEventCh:
if ev == nil {
// Unsubscription done, stop listening
dlEventCh = nil
continue
}
switch ev.Data.(type) {
case downloader.StartEvent:
wasMining := miner.Mining()
miner.worker.stop()
canStart = false
if wasMining {
// Resume mining after sync was finished
shouldStart = true
log.Info("Mining aborted due to sync")
}
case downloader.FailedEvent:
canStart = true
if shouldStart {
miner.SetEtherbase(miner.coinbase)
miner.worker.start()
}
case downloader.DoneEvent:
canStart = true
if shouldStart {
miner.SetEtherbase(miner.coinbase)
miner.worker.start()
}
// Stop reacting to downloader events
events.Unsubscribe()
}
case addr := <-miner.startCh:
if canStart {
miner.SetEtherbase(addr)
miner.worker.start()
}
shouldStart = true
case <-miner.stopCh:
shouldStart = false
miner.worker.stop()
case <-miner.exitCh:
miner.worker.close()
return
}
}
}
func (miner *Miner) Start(coinbase common.Address) {
miner.startCh <- coinbase
}
func (miner *Miner) Stop() {
miner.stopCh <- struct{}{}
}
func (miner *Miner) Close() {
close(miner.exitCh)
}
func (miner *Miner) Mining() bool {
return miner.worker.isRunning()
}
func (miner *Miner) HashRate() uint64 {
if pow, ok := miner.engine.(consensus.PoW); ok {
return uint64(pow.Hashrate())
}
return 0
}
func (miner *Miner) SetExtra(extra []byte) error {
if uint64(len(extra)) > params.MaximumExtraDataSize {
return fmt.Errorf("extra exceeds max length. %d > %v", len(extra), params.MaximumExtraDataSize)
}
miner.worker.setExtra(extra)
return nil
}
// SetRecommitInterval sets the interval for sealing work resubmitting.
func (miner *Miner) SetRecommitInterval(interval time.Duration) {
miner.worker.setRecommitInterval(interval)
}
// Pending returns the currently pending block and associated state.
func (miner *Miner) Pending() (*types.Block, *state.StateDB) {
return miner.worker.pending()
}
// PendingBlock returns the currently pending block.
//
// Note, to access both the pending block and the pending state
// simultaneously, please use Pending(), as the pending state can
// change between multiple method calls
func (miner *Miner) PendingBlock() *types.Block {
return miner.worker.pendingBlock()
}
func (miner *Miner) SetEtherbase(addr common.Address) {
miner.coinbase = addr
miner.worker.setEtherbase(addr)
}
// EnablePreseal turns on the preseal mining feature. It's enabled by default.
// Note this function shouldn't be exposed to API, it's unnecessary for users
// (miners) to actually know the underlying detail. It's only for outside project
// which uses this library.
func (miner *Miner) EnablePreseal() {
miner.worker.enablePreseal()
}
// DisablePreseal turns off the preseal mining feature. It's necessary for some
// fake consensus engine which can seal blocks instantaneously.
// Note this function shouldn't be exposed to API, it's unnecessary for users
// (miners) to actually know the underlying detail. It's only for outside project
// which uses this library.
func (miner *Miner) DisablePreseal() {
miner.worker.disablePreseal()
}
// SubscribePendingLogs starts delivering logs from pending transactions
// to the given channel.
func (miner *Miner) SubscribePendingLogs(ch chan<- []*types.Log) event.Subscription {
return miner.worker.pendingLogsFeed.Subscribe(ch)
}