diff options
Diffstat (limited to 'eth/fetcher')
| -rw-r--r-- | eth/fetcher/fetcher.go | 456 | ||||
| -rw-r--r-- | eth/fetcher/fetcher_test.go | 524 |
2 files changed, 980 insertions, 0 deletions
diff --git a/eth/fetcher/fetcher.go b/eth/fetcher/fetcher.go new file mode 100644 index 000000000..90a202235 --- /dev/null +++ b/eth/fetcher/fetcher.go @@ -0,0 +1,456 @@ +// Package fetcher contains the block announcement based synchonisation. +package fetcher + +import ( + "errors" + "fmt" + "math/rand" + "time" + + "github.com/ethereum/go-ethereum/common" + "github.com/ethereum/go-ethereum/core/types" + "github.com/ethereum/go-ethereum/logger" + "github.com/ethereum/go-ethereum/logger/glog" + "gopkg.in/karalabe/cookiejar.v2/collections/prque" +) + +const ( + arriveTimeout = 500 * time.Millisecond // Time allowance before an announced block is explicitly requested + gatherSlack = 100 * time.Millisecond // Interval used to collate almost-expired announces with fetches + 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 + 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 ( + errTerminated = errors.New("terminated") +) + +// blockRetrievalFn is a callback type for retrieving a block from the local chain. +type blockRetrievalFn func(common.Hash) *types.Block + +// blockRequesterFn is a callback type for sending a block retrieval request. +type blockRequesterFn func([]common.Hash) error + +// blockValidatorFn is a callback type to verify a block's header for fast propagation. +type blockValidatorFn func(block *types.Block, parent *types.Block) error + +// blockBroadcasterFn is a callback type for broadcasting a block to connected peers. +type blockBroadcasterFn func(block *types.Block, propagate bool) + +// chainHeightFn is a callback type to retrieve the current chain height. +type chainHeightFn func() uint64 + +// chainInsertFn is a callback type to insert a batch of blocks into the local chain. +type chainInsertFn func(types.Blocks) (int, error) + +// peerDropFn is a callback type for dropping a peer detected as malicious. +type peerDropFn func(id string) + +// announce is the hash notification of the availability of a new block in the +// network. +type announce struct { + hash common.Hash // Hash of the block being announced + time time.Time // Timestamp of the announcement + + origin string // Identifier of the peer originating the notification + fetch blockRequesterFn // Fetcher function to retrieve +} + +// inject represents a schedules import operation. +type inject struct { + origin string + block *types.Block +} + +// Fetcher is responsible for accumulating block announcements from various peers +// and scheduling them for retrieval. +type Fetcher struct { + // Various event channels + notify chan *announce + inject chan *inject + filter chan chan []*types.Block + done chan common.Hash + quit chan struct{} + + // Announce states + announces map[string]int // Per peer announce counts to prevent memory exhaustion + announced map[common.Hash][]*announce // Announced blocks, scheduled for fetching + fetching map[common.Hash]*announce // Announced blocks, currently fetching + + // Block cache + 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 + validateBlock blockValidatorFn // Checks if a block's headers have a valid proof of work + broadcastBlock blockBroadcasterFn // Broadcasts a block to connected peers + chainHeight chainHeightFn // Retrieves the current chain's height + insertChain chainInsertFn // Injects a batch of blocks into the chain + dropPeer peerDropFn // Drops a peer for misbehaving + + // Testing hooks + fetchingHook func([]common.Hash) // Method to call upon starting a block fetch + importedHook func(*types.Block) // Method to call upon successful block import +} + +// New creates a block fetcher to retrieve blocks based on hash announcements. +func New(getBlock blockRetrievalFn, validateBlock blockValidatorFn, broadcastBlock blockBroadcasterFn, chainHeight chainHeightFn, insertChain chainInsertFn, dropPeer peerDropFn) *Fetcher { + return &Fetcher{ + notify: make(chan *announce), + inject: make(chan *inject), + filter: make(chan chan []*types.Block), + done: make(chan common.Hash), + quit: make(chan struct{}), + announces: make(map[string]int), + announced: make(map[common.Hash][]*announce), + fetching: make(map[common.Hash]*announce), + queue: prque.New(), + queues: make(map[string]int), + queued: make(map[common.Hash]*inject), + getBlock: getBlock, + validateBlock: validateBlock, + broadcastBlock: broadcastBlock, + chainHeight: chainHeight, + insertChain: insertChain, + dropPeer: dropPeer, + } +} + +// Start boots up the announcement based synchoniser, accepting and processing +// hash notifications and block fetches until termination requested. +func (f *Fetcher) Start() { + go f.loop() +} + +// Stop terminates the announcement based synchroniser, canceling all pending +// operations. +func (f *Fetcher) Stop() { + close(f.quit) +} + +// Notify announces the fetcher of the potential availability of a new block in +// the network. +func (f *Fetcher) Notify(peer string, hash common.Hash, time time.Time, fetcher blockRequesterFn) error { + block := &announce{ + hash: hash, + time: time, + origin: peer, + fetch: fetcher, + } + select { + case f.notify <- block: + return nil + case <-f.quit: + return errTerminated + } +} + +// Enqueue tries to fill gaps the the fetcher's future import queue. +func (f *Fetcher) Enqueue(peer string, block *types.Block) error { + op := &inject{ + origin: peer, + block: block, + } + select { + case f.inject <- op: + return nil + case <-f.quit: + return errTerminated + } +} + +// Filter extracts all the blocks that were explicitly requested by the fetcher, +// returning those that should be handled differently. +func (f *Fetcher) Filter(blocks types.Blocks) types.Blocks { + // Send the filter channel to the fetcher + filter := make(chan []*types.Block) + + select { + case f.filter <- filter: + case <-f.quit: + return nil + } + // Request the filtering of the block list + select { + case filter <- blocks: + case <-f.quit: + return nil + } + // Retrieve the blocks remaining after filtering + select { + case blocks := <-filter: + return blocks + case <-f.quit: + return nil + } +} + +// Loop is the main fetcher loop, checking and processing various notification +// events. +func (f *Fetcher) loop() { + // Iterate the block fetching until a quit is requested + fetch := time.NewTimer(0) + for { + // Clean up any expired block fetches + for hash, announce := range f.fetching { + if time.Since(announce.time) > fetchTimeout { + f.forgetHash(hash) + } + } + // Import any queued blocks that could potentially fit + height := f.chainHeight() + for !f.queue.Empty() { + op := f.queue.PopItem().(*inject) + + // 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 + hash := op.block.Hash() + if number+maxUncleDist < height || f.getBlock(hash) != nil { + f.forgetBlock(hash) + continue + } + f.insert(op.origin, op.block) + } + // Wait for an outside event to occur + select { + case <-f.quit: + // Fetcher terminating, abort all operations + return + + case notification := <-f.notify: + // A block was announced, make sure the peer isn't DOSing us + count := f.announces[notification.origin] + 1 + 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 + if _, ok := f.fetching[notification.hash]; ok { + break + } + f.announces[notification.origin] = count + f.announced[notification.hash] = append(f.announced[notification.hash], notification) + if len(f.announced) == 1 { + f.reschedule(fetch) + } + + case op := <-f.inject: + // A direct block insertion was requested, try and fill any pending gaps + f.enqueue(op.origin, op.block) + + case hash := <-f.done: + // A pending import finished, remove all traces of the notification + f.forgetHash(hash) + f.forgetBlock(hash) + + case <-fetch.C: + // At least one block's timer ran out, check for needing retrieval + request := make(map[string][]common.Hash) + + for hash, announces := range f.announced { + 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.forgetHash(hash) + + // If the block still didn't arrive, queue for fetching + if f.getBlock(hash) == nil { + request[announce.origin] = append(request[announce.origin], hash) + f.fetching[hash] = announce + } + } + } + // Send out all block requests + for peer, hashes := range request { + if glog.V(logger.Detail) && len(hashes) > 0 { + list := "[" + for _, hash := range hashes { + list += fmt.Sprintf("%x, ", hash[:4]) + } + list = list[:len(list)-2] + "]" + + glog.V(logger.Detail).Infof("Peer %s: fetching %s", peer, list) + } + // Create a closure of the fetch and schedule in on a new thread + fetcher, hashes := f.fetching[hashes[0]].fetch, hashes + go func() { + if f.fetchingHook != nil { + f.fetchingHook(hashes) + } + fetcher(hashes) + }() + } + // Schedule the next fetch if blocks are still pending + f.reschedule(fetch) + + case filter := <-f.filter: + // Blocks arrived, extract any explicit fetches, return all else + var blocks types.Blocks + select { + case blocks = <-filter: + case <-f.quit: + return + } + + explicit, download := []*types.Block{}, []*types.Block{} + for _, block := range blocks { + hash := block.Hash() + + // Filter explicitly requested blocks from hash announcements + if _, ok := f.fetching[hash]; ok { + // Discard if already imported by other means + if f.getBlock(hash) == nil { + explicit = append(explicit, block) + } else { + f.forgetHash(hash) + } + } else { + download = append(download, block) + } + } + + select { + case filter <- download: + case <-f.quit: + return + } + // Schedule the retrieved blocks for ordered import + for _, block := range explicit { + if announce := f.fetching[block.Hash()]; announce != nil { + f.enqueue(announce.origin, block) + } + } + } + } +} + +// reschedule resets the specified fetch timer to the next announce timeout. +func (f *Fetcher) reschedule(fetch *time.Timer) { + // Short circuit if no blocks are announced + if len(f.announced) == 0 { + return + } + // Otherwise find the earliest expiring announcement + earliest := time.Now() + for _, announces := range f.announced { + if earliest.After(announces[0].time) { + earliest = announces[0].time + } + } + fetch.Reset(arriveTimeout - time.Since(earliest)) +} + +// enqueue schedules a new future import operation, if the block to be imported +// has not yet been seen. +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) + return + } + // Schedule the block for future importing + if _, ok := f.queued[hash]; !ok { + 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()) + } + } +} + +// insert spawns a new goroutine to run a block insertion into the chain. If the +// block's number is at the same height as the current import phase, if updates +// the phase states accordingly. +func (f *Fetcher) insert(peer string, block *types.Block) { + hash := block.Hash() + + // Run the import on a new thread + glog.V(logger.Debug).Infof("Peer %s: importing block #%d [%x]", peer, block.NumberU64(), hash[:4]) + go func() { + defer func() { f.done <- hash }() + + // If the parent's unknown, abort insertion + parent := f.getBlock(block.ParentHash()) + if parent == nil { + return + } + // Quickly validate the header and propagate the block if it passes + if err := f.validateBlock(block, parent); err != nil { + glog.V(logger.Debug).Infof("Peer %s: block #%d [%x] verification failed: %v", peer, block.NumberU64(), hash[:4], err) + f.dropPeer(peer) + return + } + go f.broadcastBlock(block, true) + + // Run the actual import and log any issues + if _, err := f.insertChain(types.Blocks{block}); err != nil { + glog.V(logger.Warn).Infof("Peer %s: block #%d [%x] import failed: %v", peer, block.NumberU64(), hash[:4], err) + return + } + // If import succeeded, broadcast the block + go f.broadcastBlock(block, false) + + // Invoke the testing hook if needed + if f.importedHook != nil { + f.importedHook(block) + } + }() +} + +// 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]-- + if f.announces[announce.origin] == 0 { + delete(f.announces, announce.origin) + } + } + delete(f.announced, hash) + + // Remove any pending fetches and decrement the DOS counters + if announce := f.fetching[hash]; announce != nil { + f.announces[announce.origin]-- + if f.announces[announce.origin] == 0 { + delete(f.announces, announce.origin) + } + 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) + } +} diff --git a/eth/fetcher/fetcher_test.go b/eth/fetcher/fetcher_test.go new file mode 100644 index 000000000..80247d9d2 --- /dev/null +++ b/eth/fetcher/fetcher_test.go @@ -0,0 +1,524 @@ +package fetcher + +import ( + "encoding/binary" + "errors" + "math/big" + "sync" + "sync/atomic" + "testing" + "time" + + "github.com/ethereum/go-ethereum/common" + "github.com/ethereum/go-ethereum/core/types" +) + +var ( + knownHash = common.Hash{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1} + unknownHash = common.Hash{2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2} + bannedHash = common.Hash{3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3} + + genesis = createBlock(1, common.Hash{}, knownHash) +) + +// idCounter is used by the createHashes method the generate deterministic but unique hashes +var idCounter = int64(2) // #1 is the genesis block + +// createHashes generates a batch of hashes rooted at a specific point in the chain. +func createHashes(amount int, root common.Hash) (hashes []common.Hash) { + hashes = make([]common.Hash, amount+1) + hashes[len(hashes)-1] = root + + for i := 0; i < len(hashes)-1; i++ { + binary.BigEndian.PutUint64(hashes[i][:8], uint64(idCounter)) + idCounter++ + } + return +} + +// createBlock assembles a new block at the given chain height. +func createBlock(i int, parent, hash common.Hash) *types.Block { + header := &types.Header{Number: big.NewInt(int64(i))} + block := types.NewBlockWithHeader(header) + block.HeaderHash = hash + block.ParentHeaderHash = parent + return block +} + +// copyBlock makes a deep copy of a block suitable for local modifications. +func copyBlock(block *types.Block) *types.Block { + return createBlock(int(block.Number().Int64()), block.ParentHeaderHash, block.HeaderHash) +} + +// createBlocksFromHashes assembles a collection of blocks, each having a correct +// place in the given hash chain. +func createBlocksFromHashes(hashes []common.Hash) map[common.Hash]*types.Block { + blocks := make(map[common.Hash]*types.Block) + for i := 0; i < len(hashes); i++ { + parent := knownHash + if i < len(hashes)-1 { + parent = hashes[i+1] + } + blocks[hashes[i]] = createBlock(len(hashes)-i, parent, hashes[i]) + } + return blocks +} + +// fetcherTester is a test simulator for mocking out local block chain. +type fetcherTester struct { + fetcher *Fetcher + + hashes []common.Hash // Hash chain belonging to the tester + blocks map[common.Hash]*types.Block // Blocks belonging to the tester + + lock sync.RWMutex +} + +// newTester creates a new fetcher test mocker. +func newTester() *fetcherTester { + tester := &fetcherTester{ + hashes: []common.Hash{knownHash}, + blocks: map[common.Hash]*types.Block{knownHash: genesis}, + } + tester.fetcher = New(tester.getBlock, tester.verifyBlock, tester.broadcastBlock, tester.chainHeight, tester.insertChain, tester.dropPeer) + tester.fetcher.Start() + + return tester +} + +// getBlock retrieves a block from the tester's block chain. +func (f *fetcherTester) getBlock(hash common.Hash) *types.Block { + f.lock.RLock() + defer f.lock.RUnlock() + + return f.blocks[hash] +} + +// verifyBlock is a nop placeholder for the block header verification. +func (f *fetcherTester) verifyBlock(block *types.Block, parent *types.Block) error { + return nil +} + +// broadcastBlock is a nop placeholder for the block broadcasting. +func (f *fetcherTester) broadcastBlock(block *types.Block, propagate bool) { +} + +// chainHeight retrieves the current height (block number) of the chain. +func (f *fetcherTester) chainHeight() uint64 { + f.lock.RLock() + defer f.lock.RUnlock() + + return f.blocks[f.hashes[len(f.hashes)-1]].NumberU64() +} + +// insertChain injects a new blocks into the simulated chain. +func (f *fetcherTester) insertChain(blocks types.Blocks) (int, error) { + f.lock.Lock() + defer f.lock.Unlock() + + for i, block := range blocks { + // Make sure the parent in known + if _, ok := f.blocks[block.ParentHash()]; !ok { + return i, errors.New("unknown parent") + } + // Discard any new blocks if the same height already exists + if block.NumberU64() <= f.blocks[f.hashes[len(f.hashes)-1]].NumberU64() { + return i, nil + } + // Otherwise build our current chain + f.hashes = append(f.hashes, block.Hash()) + f.blocks[block.Hash()] = block + } + return 0, nil +} + +// dropPeer is a nop placeholder for the peer removal. +func (f *fetcherTester) dropPeer(peer string) { +} + +// peerFetcher retrieves a fetcher associated with a simulated peer. +func (f *fetcherTester) makeFetcher(blocks map[common.Hash]*types.Block) blockRequesterFn { + // Copy all the blocks to ensure they are not tampered with + closure := make(map[common.Hash]*types.Block) + for hash, block := range blocks { + closure[hash] = copyBlock(block) + } + // Create a function that returns blocks from the closure + return func(hashes []common.Hash) error { + // Gather the blocks to return + blocks := make([]*types.Block, 0, len(hashes)) + for _, hash := range hashes { + if block, ok := closure[hash]; ok { + blocks = append(blocks, block) + } + } + // Return on a new thread + go f.fetcher.Filter(blocks) + + return nil + } +} + +// verifyImportEvent verifies that one single event arrive on an import channel. +func verifyImportEvent(t *testing.T, imported chan *types.Block) { + select { + case <-imported: + case <-time.After(time.Second): + t.Fatalf("import timeout") + } +} + +// verifyImportCount verifies that exactly count number of events arrive on an +// import hook channel. +func verifyImportCount(t *testing.T, imported chan *types.Block, count int) { + for i := 0; i < count; i++ { + select { + case <-imported: + case <-time.After(time.Second): + t.Fatalf("block %d: import timeout", i) + } + } + verifyImportDone(t, imported) +} + +// verifyImportDone verifies that no more events are arriving on an import channel. +func verifyImportDone(t *testing.T, imported chan *types.Block) { + select { + case <-imported: + t.Fatalf("extra block imported") + case <-time.After(50 * time.Millisecond): + } +} + +// Tests that a fetcher accepts block announcements and initiates retrievals for +// them, successfully importing into the local chain. +func TestSequentialAnnouncements(t *testing.T) { + // Create a chain of blocks to import + targetBlocks := 4 * hashLimit + hashes := createHashes(targetBlocks, knownHash) + blocks := createBlocksFromHashes(hashes) + + tester := newTester() + fetcher := tester.makeFetcher(blocks) + + // Iteratively announce blocks until all are imported + imported := make(chan *types.Block) + tester.fetcher.importedHook = func(block *types.Block) { imported <- block } + + for i := len(hashes) - 2; i >= 0; i-- { + tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher) + verifyImportEvent(t, imported) + } + verifyImportDone(t, imported) +} + +// Tests that if blocks are announced by multiple peers (or even the same buggy +// peer), they will only get downloaded at most once. +func TestConcurrentAnnouncements(t *testing.T) { + // Create a chain of blocks to import + targetBlocks := 4 * hashLimit + hashes := createHashes(targetBlocks, knownHash) + blocks := createBlocksFromHashes(hashes) + + // Assemble a tester with a built in counter for the requests + tester := newTester() + fetcher := tester.makeFetcher(blocks) + + counter := uint32(0) + wrapper := func(hashes []common.Hash) error { + atomic.AddUint32(&counter, uint32(len(hashes))) + return fetcher(hashes) + } + // Iteratively announce blocks until all are imported + imported := make(chan *types.Block) + tester.fetcher.importedHook = func(block *types.Block) { imported <- block } + + for i := len(hashes) - 2; i >= 0; i-- { + tester.fetcher.Notify("first", hashes[i], time.Now().Add(-arriveTimeout), wrapper) + tester.fetcher.Notify("second", hashes[i], time.Now().Add(-arriveTimeout+time.Millisecond), wrapper) + tester.fetcher.Notify("second", hashes[i], time.Now().Add(-arriveTimeout-time.Millisecond), wrapper) + + verifyImportEvent(t, imported) + } + verifyImportDone(t, imported) + + // Make sure no blocks were retrieved twice + if int(counter) != targetBlocks { + t.Fatalf("retrieval count mismatch: have %v, want %v", counter, targetBlocks) + } +} + +// Tests that announcements arriving while a previous is being fetched still +// results in a valid import. +func TestOverlappingAnnouncements(t *testing.T) { + // Create a chain of blocks to import + targetBlocks := 4 * hashLimit + hashes := createHashes(targetBlocks, knownHash) + blocks := createBlocksFromHashes(hashes) + + tester := newTester() + fetcher := tester.makeFetcher(blocks) + + // Iteratively announce blocks, but overlap them continuously + fetching := make(chan []common.Hash) + imported := make(chan *types.Block, len(hashes)-1) + tester.fetcher.fetchingHook = func(hashes []common.Hash) { fetching <- hashes } + tester.fetcher.importedHook = func(block *types.Block) { imported <- block } + + for i := len(hashes) - 2; i >= 0; i-- { + tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher) + select { + case <-fetching: + case <-time.After(time.Second): + t.Fatalf("hash %d: announce timeout", len(hashes)-i) + } + } + // Wait for all the imports to complete and check count + verifyImportCount(t, imported, len(hashes)-1) +} + +// Tests that announces already being retrieved will not be duplicated. +func TestPendingDeduplication(t *testing.T) { + // Create a hash and corresponding block + hashes := createHashes(1, knownHash) + blocks := createBlocksFromHashes(hashes) + + // Assemble a tester with a built in counter and delayed fetcher + tester := newTester() + fetcher := tester.makeFetcher(blocks) + + delay := 50 * time.Millisecond + counter := uint32(0) + wrapper := func(hashes []common.Hash) error { + atomic.AddUint32(&counter, uint32(len(hashes))) + + // Simulate a long running fetch + go func() { + time.Sleep(delay) + fetcher(hashes) + }() + return nil + } + // Announce the same block many times until it's fetched (wait for any pending ops) + for tester.getBlock(hashes[0]) == nil { + tester.fetcher.Notify("repeater", hashes[0], time.Now().Add(-arriveTimeout), wrapper) + time.Sleep(time.Millisecond) + } + time.Sleep(delay) + + // Check that all blocks were imported and none fetched twice + if imported := len(tester.blocks); imported != 2 { + t.Fatalf("synchronised block mismatch: have %v, want %v", imported, 2) + } + if int(counter) != 1 { + t.Fatalf("retrieval count mismatch: have %v, want %v", counter, 1) + } +} + +// Tests that announcements retrieved in a random order are cached and eventually +// imported when all the gaps are filled in. +func TestRandomArrivalImport(t *testing.T) { + // Create a chain of blocks to import, and choose one to delay + hashes := createHashes(maxQueueDist, knownHash) + blocks := createBlocksFromHashes(hashes) + skip := maxQueueDist / 2 + + tester := newTester() + fetcher := tester.makeFetcher(blocks) + + // Iteratively announce blocks, skipping one entry + imported := make(chan *types.Block, len(hashes)-1) + tester.fetcher.importedHook = func(block *types.Block) { imported <- block } + + for i := len(hashes) - 1; i >= 0; i-- { + if i != skip { + tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher) + time.Sleep(time.Millisecond) + } + } + // Finally announce the skipped entry and check full import + tester.fetcher.Notify("valid", hashes[skip], time.Now().Add(-arriveTimeout), fetcher) + verifyImportCount(t, imported, len(hashes)-1) +} + +// Tests that direct block enqueues (due to block propagation vs. hash announce) +// are correctly schedule, filling and import queue gaps. +func TestQueueGapFill(t *testing.T) { + // Create a chain of blocks to import, and choose one to not announce at all + hashes := createHashes(maxQueueDist, knownHash) + blocks := createBlocksFromHashes(hashes) + skip := maxQueueDist / 2 + + tester := newTester() + fetcher := tester.makeFetcher(blocks) + + // Iteratively announce blocks, skipping one entry + imported := make(chan *types.Block, len(hashes)-1) + tester.fetcher.importedHook = func(block *types.Block) { imported <- block } + + for i := len(hashes) - 1; i >= 0; i-- { + if i != skip { + tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher) + time.Sleep(time.Millisecond) + } + } + // Fill the missing block directly as if propagated + tester.fetcher.Enqueue("valid", blocks[hashes[skip]]) + verifyImportCount(t, imported, len(hashes)-1) +} + +// Tests that blocks arriving from various sources (multiple propagations, hash +// announces, etc) do not get scheduled for import multiple times. +func TestImportDeduplication(t *testing.T) { + // Create two blocks to import (one for duplication, the other for stalling) + hashes := createHashes(2, knownHash) + blocks := createBlocksFromHashes(hashes) + + // Create the tester and wrap the importer with a counter + tester := newTester() + fetcher := tester.makeFetcher(blocks) + + counter := uint32(0) + tester.fetcher.insertChain = func(blocks types.Blocks) (int, error) { + atomic.AddUint32(&counter, uint32(len(blocks))) + return tester.insertChain(blocks) + } + // Instrument the fetching and imported events + fetching := make(chan []common.Hash) + imported := make(chan *types.Block, len(hashes)-1) + tester.fetcher.fetchingHook = func(hashes []common.Hash) { fetching <- hashes } + tester.fetcher.importedHook = func(block *types.Block) { imported <- block } + + // Announce the duplicating block, wait for retrieval, and also propagate directly + tester.fetcher.Notify("valid", hashes[0], time.Now().Add(-arriveTimeout), fetcher) + <-fetching + + tester.fetcher.Enqueue("valid", blocks[hashes[0]]) + tester.fetcher.Enqueue("valid", blocks[hashes[0]]) + tester.fetcher.Enqueue("valid", blocks[hashes[0]]) + + // Fill the missing block directly as if propagated, and check import uniqueness + tester.fetcher.Enqueue("valid", blocks[hashes[1]]) + verifyImportCount(t, imported, 2) + + if counter != 2 { + t.Fatalf("import invocation count mismatch: have %v, want %v", counter, 2) + } +} + +// Tests that blocks with numbers much lower or higher than out current head get +// discarded no prevent wasting resources on useless blocks from faulty peers. +func TestDistantDiscarding(t *testing.T) { + // Create a long chain to import + hashes := createHashes(3*maxQueueDist, knownHash) + blocks := createBlocksFromHashes(hashes) + + head := hashes[len(hashes)/2] + + // Create a tester and simulate a head block being the middle of the above chain + tester := newTester() + tester.hashes = []common.Hash{head} + tester.blocks = map[common.Hash]*types.Block{head: blocks[head]} + + // Ensure that a block with a lower number than the threshold is discarded + tester.fetcher.Enqueue("lower", blocks[hashes[0]]) + time.Sleep(10 * time.Millisecond) + if !tester.fetcher.queue.Empty() { + t.Fatalf("fetcher queued stale block") + } + // Ensure that a block with a higher number than the threshold is discarded + tester.fetcher.Enqueue("higher", blocks[hashes[len(hashes)-1]]) + time.Sleep(10 * time.Millisecond) + if !tester.fetcher.queue.Empty() { + t.Fatalf("fetcher queued future block") + } +} + +// Tests that a peer is unable to use unbounded memory with sending infinite +// block announcements to a node, but that even in the face of such an attack, +// the fetcher remains operational. +func TestHashMemoryExhaustionAttack(t *testing.T) { + // Create a tester with instrumented import hooks + tester := newTester() + + imported := make(chan *types.Block) + tester.fetcher.importedHook = func(block *types.Block) { imported <- block } + + // Create a valid chain and an infinite junk chain + hashes := createHashes(hashLimit+2*maxQueueDist, knownHash) + blocks := createBlocksFromHashes(hashes) + valid := tester.makeFetcher(blocks) + + attack := createHashes(hashLimit+2*maxQueueDist, unknownHash) + attacker := tester.makeFetcher(nil) + + // Feed the tester a huge hashset from the attacker, and a limited from the valid peer + for i := 0; i < len(attack); i++ { + if i < maxQueueDist { + tester.fetcher.Notify("valid", hashes[len(hashes)-2-i], time.Now(), valid) + } + tester.fetcher.Notify("attacker", attack[i], time.Now(), attacker) + } + if len(tester.fetcher.announced) != hashLimit+maxQueueDist { + t.Fatalf("queued announce count mismatch: have %d, want %d", len(tester.fetcher.announced), hashLimit+maxQueueDist) + } + // Wait for fetches to complete + verifyImportCount(t, imported, maxQueueDist) + + // Feed the remaining valid hashes to ensure DOS protection state remains clean + for i := len(hashes) - maxQueueDist - 2; i >= 0; i-- { + tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), valid) + verifyImportEvent(t, imported) + } + verifyImportDone(t, imported) +} + +// Tests that blocks sent to the fetcher (either through propagation or via hash +// announces and retrievals) don't pile up indefinitely, exhausting available +// system memory. +func TestBlockMemoryExhaustionAttack(t *testing.T) { + // Create a tester with instrumented import hooks + tester := newTester() + + imported := make(chan *types.Block) + tester.fetcher.importedHook = func(block *types.Block) { imported <- block } + + // Create a valid chain and a batch of dangling (but in range) blocks + hashes := createHashes(blockLimit+2*maxQueueDist, knownHash) + blocks := createBlocksFromHashes(hashes) + + attack := make(map[common.Hash]*types.Block) + for len(attack) < blockLimit+2*maxQueueDist { + hashes := createHashes(maxQueueDist-1, unknownHash) + blocks := createBlocksFromHashes(hashes) + for _, hash := range hashes[:maxQueueDist-2] { + attack[hash] = blocks[hash] + } + } + // Try to feed all the attacker blocks make sure only a limited batch is accepted + for _, block := range attack { + tester.fetcher.Enqueue("attacker", block) + } + time.Sleep(100 * time.Millisecond) + if queued := tester.fetcher.queue.Size(); queued != blockLimit { + t.Fatalf("queued block count mismatch: have %d, want %d", queued, blockLimit) + } + // Queue up a batch of valid blocks, and check that a new peer is allowed to do so + for i := 0; i < maxQueueDist-1; i++ { + tester.fetcher.Enqueue("valid", blocks[hashes[len(hashes)-3-i]]) + } + time.Sleep(100 * time.Millisecond) + if queued := tester.fetcher.queue.Size(); queued != blockLimit+maxQueueDist-1 { + t.Fatalf("queued block count mismatch: have %d, want %d", queued, blockLimit+maxQueueDist-1) + } + // Insert the missing piece (and sanity check the import) + tester.fetcher.Enqueue("valid", blocks[hashes[len(hashes)-2]]) + verifyImportCount(t, imported, maxQueueDist) + + // Insert the remaining blocks in chunks to ensure clean DOS protection + for i := maxQueueDist; i < len(hashes)-1; i++ { + tester.fetcher.Enqueue("valid", blocks[hashes[len(hashes)-2-i]]) + verifyImportEvent(t, imported) + } + verifyImportDone(t, imported) +} |