Merge branch 'release/0.9.32'v0.9.32

1 files changed, 456 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)
+	}
+}