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eth/fetcher: handle and (crude) test block memory DOS

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This commit is contained in:
Péter Szilágyi
2015-06-22 16:49:47 +03:00
parent d36c25bcbc
commit 1989d1491a
2 changed files with 105 additions and 23 deletions
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61
eth/fetcher/fetcher.go
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@ -20,7 +20,8 @@ const (
fetchTimeout = 5 * time.Second // Maximum alloted time to return an explicitly requested block
maxUncleDist = 7 // Maximum allowed backward distance from the chain head
maxQueueDist = 32 // Maximum allowed distance from the chain head to queue
announceLimit = 256 // Maximum number of unique blocks a peer may have announced
hashLimit = 256 // Maximum number of unique blocks a peer may have announced
blockLimit = 64 // Maximum number of unique blocks a per may have delivered
)
var (
@ -80,8 +81,9 @@ type Fetcher struct {
fetching map[common.Hash]*announce // Announced blocks, currently fetching
// Block cache
queue *prque.Prque // Queue containing the import operations (block number sorted)
queued map[common.Hash]struct{} // Presence set of already queued blocks (to dedup imports)
queue *prque.Prque // Queue containing the import operations (block number sorted)
queues map[string]int // Per peer block counts to prevent memory exhaustion
queued map[common.Hash]*inject // Set of already queued blocks (to dedup imports)
// Callbacks
getBlock blockRetrievalFn // Retrieves a block from the local chain
@ -104,7 +106,8 @@ func New(getBlock blockRetrievalFn, validateBlock blockValidatorFn, broadcastBlo
announced: make(map[common.Hash][]*announce),
fetching: make(map[common.Hash]*announce),
queue: prque.New(),
queued: make(map[common.Hash]struct{}),
queues: make(map[string]int),
queued: make(map[common.Hash]*inject),
getBlock: getBlock,
validateBlock: validateBlock,
broadcastBlock: broadcastBlock,
@ -192,22 +195,24 @@ func (f *Fetcher) loop() {
// Clean up any expired block fetches
for hash, announce := range f.fetching {
if time.Since(announce.time) > fetchTimeout {
f.forgetBlock(hash)
f.forgetHash(hash)
}
}
// Import any queued blocks that could potentially fit
height := f.chainHeight()
for !f.queue.Empty() {
op := f.queue.PopItem().(*inject)
number := op.block.NumberU64()
// If too high up the chain or phase, continue later
number := op.block.NumberU64()
if number > height+1 {
f.queue.Push(op, -float32(op.block.NumberU64()))
break
}
// Otherwise if fresh and still unknown, try and import
if number+maxUncleDist < height || f.getBlock(op.block.Hash()) != nil {
hash := op.block.Hash()
if number+maxUncleDist < height || f.getBlock(hash) != nil {
f.forgetBlock(hash)
continue
}
f.insert(op.origin, op.block)
@ -221,8 +226,8 @@ func (f *Fetcher) loop() {
case notification := <-f.notify:
// A block was announced, make sure the peer isn't DOSing us
count := f.announces[notification.origin] + 1
if count > announceLimit {
glog.V(logger.Debug).Infof("Peer %s: exceeded outstanding announces (%d)", notification.origin, announceLimit)
if count > hashLimit {
glog.V(logger.Debug).Infof("Peer %s: exceeded outstanding announces (%d)", notification.origin, hashLimit)
break
}
// All is well, schedule the announce if block's not yet downloading
@ -241,8 +246,8 @@ func (f *Fetcher) loop() {
case hash := <-f.done:
// A pending import finished, remove all traces of the notification
f.forgetHash(hash)
f.forgetBlock(hash)
delete(f.queued, hash)
case <-fetch.C:
// At least one block's timer ran out, check for needing retrieval
@ -252,7 +257,7 @@ func (f *Fetcher) loop() {
if time.Since(announces[0].time) > arriveTimeout-gatherSlack {
// Pick a random peer to retrieve from, reset all others
announce := announces[rand.Intn(len(announces))]
f.forgetBlock(hash)
f.forgetHash(hash)
// If the block still didn't arrive, queue for fetching
if f.getBlock(hash) == nil {
@ -296,7 +301,7 @@ func (f *Fetcher) loop() {
if f.getBlock(hash) == nil {
explicit = append(explicit, block)
} else {
f.forgetBlock(hash)
f.forgetHash(hash)
}
} else {
download = append(download, block)
@ -339,6 +344,12 @@ func (f *Fetcher) reschedule(fetch *time.Timer) {
func (f *Fetcher) enqueue(peer string, block *types.Block) {
hash := block.Hash()
// Ensure the peer isn't DOSing us
count := f.queues[peer] + 1
if count > blockLimit {
glog.V(logger.Debug).Infof("Peer %s: discarded block #%d [%x], exceeded allowance (%d)", peer, block.NumberU64(), hash.Bytes()[:4], blockLimit)
return
}
// Discard any past or too distant blocks
if dist := int64(block.NumberU64()) - int64(f.chainHeight()); dist < -maxUncleDist || dist > maxQueueDist {
glog.V(logger.Debug).Infof("Peer %s: discarded block #%d [%x], distance %d", peer, block.NumberU64(), hash.Bytes()[:4], dist)
@ -346,8 +357,13 @@ func (f *Fetcher) enqueue(peer string, block *types.Block) {
}
// Schedule the block for future importing
if _, ok := f.queued[hash]; !ok {
f.queued[hash] = struct{}{}
f.queue.Push(&inject{origin: peer, block: block}, -float32(block.NumberU64()))
op := &inject{
origin: peer,
block: block,
}
f.queues[peer] = count
f.queued[hash] = op
f.queue.Push(op, -float32(block.NumberU64()))
if glog.V(logger.Debug) {
glog.Infof("Peer %s: queued block #%d [%x], total %v", peer, block.NumberU64(), hash.Bytes()[:4], f.queue.Size())
@ -389,8 +405,9 @@ func (f *Fetcher) insert(peer string, block *types.Block) {
}()
}
// forgetBlock removes all traces of a block from the fetcher's internal state.
func (f *Fetcher) forgetBlock(hash common.Hash) {
// forgetHash removes all traces of a block announcement from the fetcher's
// internal state.
func (f *Fetcher) forgetHash(hash common.Hash) {
// Remove all pending announces and decrement DOS counters
for _, announce := range f.announced[hash] {
f.announces[announce.origin]--
@ -409,3 +426,15 @@ func (f *Fetcher) forgetBlock(hash common.Hash) {
delete(f.fetching, hash)
}
}
// forgetBlock removes all traces of a queued block frmo the fetcher's internal
// state.
func (f *Fetcher) forgetBlock(hash common.Hash) {
if insert := f.queued[hash]; insert != nil {
f.queues[insert.origin]--
if f.queues[insert.origin] == 0 {
delete(f.queues, insert.origin)
}
delete(f.queued, hash)
}
}