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blocker.go
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blocker.go
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// Copyright 2021 The Swarm Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package blocker
import (
"fmt"
"sync"
"time"
"github.com/ethersphere/bee/pkg/log"
"github.com/ethersphere/bee/pkg/p2p"
"github.com/ethersphere/bee/pkg/swarm"
"go.uber.org/atomic"
)
// loggerName is the tree path name of the logger for this package.
const loggerName = "blocker"
// sequencerResolution represents monotonic sequencer resolution.
// It must be in the time.Duration base form without a multiplier.
var sequencerResolution = time.Second
type peer struct {
blockAfter uint64
address swarm.Address
}
type Blocker struct {
sequence atomic.Uint64 // Monotonic clock.
mu sync.Mutex
blocklister p2p.Blocklister
flagTimeout time.Duration // how long before blocking a flagged peer
blockDuration time.Duration // how long to blocklist a bad peer
peers map[string]*peer
logger log.Logger
wakeupCh chan struct{}
quit chan struct{}
closeWg sync.WaitGroup
blocklistCallback func(swarm.Address)
}
func New(blocklister p2p.Blocklister, flagTimeout, blockDuration, wakeUpTime time.Duration, callback func(swarm.Address), logger log.Logger) *Blocker {
if flagTimeout <= sequencerResolution {
panic(fmt.Errorf("flag timeout %v cannot be equal to or lower then the sequencer resolution %v", flagTimeout, sequencerResolution))
}
if wakeUpTime < sequencerResolution {
panic(fmt.Errorf("wakeup time %v cannot be lower then the clock sequencer resolution %v", wakeUpTime, sequencerResolution))
}
b := &Blocker{
blocklister: blocklister,
flagTimeout: flagTimeout,
blockDuration: blockDuration,
peers: map[string]*peer{},
wakeupCh: make(chan struct{}),
quit: make(chan struct{}),
logger: logger.WithName(loggerName).Register(),
closeWg: sync.WaitGroup{},
blocklistCallback: callback,
}
b.closeWg.Add(1)
go func() {
defer b.closeWg.Done()
for {
select {
case <-b.quit:
return
case <-time.After(sequencerResolution):
if b.blocklister.NetworkStatus() == p2p.NetworkStatusAvailable {
b.sequence.Inc()
}
}
}
}()
b.closeWg.Add(1)
go func() {
defer b.closeWg.Done()
for {
select {
case <-time.After(wakeUpTime):
b.block()
case <-b.quit:
return
}
}
}()
return b
}
func (b *Blocker) block() {
b.mu.Lock()
defer b.mu.Unlock()
for key, peer := range b.peers {
select {
case <-b.quit:
return
default:
}
if 0 < peer.blockAfter && peer.blockAfter < b.sequence.Load() {
if err := b.blocklister.Blocklist(peer.address, b.blockDuration, "blocker: flag timeout"); err != nil {
b.logger.Warning("blocking peer failed", "peer_address", peer.address, "error", err)
}
if b.blocklistCallback != nil {
b.blocklistCallback(peer.address)
}
delete(b.peers, key)
}
}
}
func (b *Blocker) Flag(addr swarm.Address) {
if b.blocklister.NetworkStatus() != p2p.NetworkStatusAvailable {
return
}
b.mu.Lock()
defer b.mu.Unlock()
if _, ok := b.peers[addr.ByteString()]; !ok {
b.peers[addr.ByteString()] = &peer{
blockAfter: b.sequence.Load() + uint64(b.flagTimeout/sequencerResolution),
address: addr,
}
}
}
func (b *Blocker) Unflag(addr swarm.Address) {
b.mu.Lock()
defer b.mu.Unlock()
delete(b.peers, addr.ByteString())
}
func (b *Blocker) PruneUnseen(seen []swarm.Address) {
isSeen := func(addr string) bool {
for _, a := range seen {
if a.ByteString() == addr {
return true
}
}
return false
}
b.mu.Lock()
defer b.mu.Unlock()
for a := range b.peers {
if !isSeen(a) {
delete(b.peers, a)
}
}
}
// Close will exit the worker loop.
// must be called only once.
func (b *Blocker) Close() error {
close(b.quit)
b.closeWg.Wait()
return nil
}