eth, eth/downloader: move peer removal into downloader

1 files changed, 59 insertions, 28 deletions

diff --git a/eth/downloader/downloader.go b/eth/downloader/downloader.go
index f0a515d12..499b3a585 100644
--- a/eth/downloader/downloader.go
+++ b/eth/downloader/downloader.go
@@ -32,28 +32,32 @@ var (
 
 var (
 	errLowTd            = errors.New("peers TD is too low")
-	ErrBusy             = errors.New("busy")
+	errBusy             = errors.New("busy")
 	errUnknownPeer      = errors.New("peer is unknown or unhealthy")
-	ErrBadPeer          = errors.New("action from bad peer ignored")
-	ErrStallingPeer     = errors.New("peer is stalling")
+	errBadPeer          = errors.New("action from bad peer ignored")
+	errStallingPeer     = errors.New("peer is stalling")
 	errBannedHead       = errors.New("peer head hash already banned")
 	errNoPeers          = errors.New("no peers to keep download active")
-	ErrPendingQueue     = errors.New("pending items in queue")
-	ErrTimeout          = errors.New("timeout")
-	ErrEmptyHashSet     = errors.New("empty hash set by peer")
+	errPendingQueue     = errors.New("pending items in queue")
+	errTimeout          = errors.New("timeout")
+	errEmptyHashSet     = errors.New("empty hash set by peer")
 	errPeersUnavailable = errors.New("no peers available or all peers tried for block download process")
 	errAlreadyInPool    = errors.New("hash already in pool")
-	ErrInvalidChain     = errors.New("retrieved hash chain is invalid")
-	ErrCrossCheckFailed = errors.New("block cross-check failed")
+	errInvalidChain     = errors.New("retrieved hash chain is invalid")
+	errCrossCheckFailed = errors.New("block cross-check failed")
 	errCancelHashFetch  = errors.New("hash fetching cancelled (requested)")
 	errCancelBlockFetch = errors.New("block downloading cancelled (requested)")
 	errNoSyncActive     = errors.New("no sync active")
 )
 
+// hashCheckFn is a callback type for verifying a hash's presence in the local chain.
 type hashCheckFn func(common.Hash) bool
-type getBlockFn func(common.Hash) *types.Block
-type chainInsertFn func(types.Blocks) (int, error)
-type hashIterFn func() (common.Hash, error)
+
+// blockRetrievalFn is a callback type for retrieving a block from the local chain.
+type blockRetrievalFn func(common.Hash) *types.Block
+
+// peerDropFn is a callback type for dropping a peer detected as malicious.
+type peerDropFn func(id string)
 
 type blockPack struct {
 	peerId string
@@ -85,8 +89,9 @@ type Downloader struct {
 	importLock  sync.Mutex
 
 	// Callbacks
-	hasBlock hashCheckFn
-	getBlock getBlockFn
+	hasBlock hashCheckFn      // Checks if a block is present in the chain
+	getBlock blockRetrievalFn // Retrieves a block from the chain
+	dropPeer peerDropFn       // Retrieved the TD of our own chain
 
 	// Status
 	synchronising int32
@@ -107,7 +112,8 @@ type Block struct {
 	OriginPeer string
 }
 
-func New(mux *event.TypeMux, hasBlock hashCheckFn, getBlock getBlockFn) *Downloader {
+// New creates a new downloader to fetch hashes and blocks from remote peers.
+func New(mux *event.TypeMux, hasBlock hashCheckFn, getBlock blockRetrievalFn, dropPeer peerDropFn) *Downloader {
 	// Create the base downloader
 	downloader := &Downloader{
 		mux:       mux,
@@ -115,6 +121,7 @@ func New(mux *event.TypeMux, hasBlock hashCheckFn, getBlock getBlockFn) *Downloa
 		peers:     newPeerSet(),
 		hasBlock:  hasBlock,
 		getBlock:  getBlock,
+		dropPeer:  dropPeer,
 		newPeerCh: make(chan *peer, 1),
 		hashCh:    make(chan hashPack, 1),
 		blockCh:   make(chan blockPack, 1),
@@ -183,19 +190,43 @@ func (d *Downloader) UnregisterPeer(id string) error {
 	return nil
 }
 
-// Synchronise will select the peer and use it for synchronising. If an empty string is given
+// Synchronise tries to sync up our local block chain with a remote peer, both
+// adding various sanity checks as well as wrapping it with various log entries.
+func (d *Downloader) Synchronise(id string, head common.Hash) {
+	glog.V(logger.Detail).Infof("Attempting synchronisation: %v, 0x%x", id, head)
+
+	switch err := d.synchronise(id, head); err {
+	case nil:
+		glog.V(logger.Detail).Infof("Synchronisation completed")
+
+	case errBusy:
+		glog.V(logger.Detail).Infof("Synchronisation already in progress")
+
+	case errTimeout, errBadPeer, errEmptyHashSet, errInvalidChain, errCrossCheckFailed:
+		glog.V(logger.Debug).Infof("Removing peer %v: %v", id, err)
+		d.dropPeer(id)
+
+	case errPendingQueue:
+		glog.V(logger.Debug).Infoln("Synchronisation aborted:", err)
+
+	default:
+		glog.V(logger.Warn).Infof("Synchronisation failed: %v", err)
+	}
+}
+
+// synchronise will select the peer and use it for synchronising. If an empty string is given
 // it will use the best peer possible and synchronize if it's TD is higher than our own. If any of the
 // checks fail an error will be returned. This method is synchronous
-func (d *Downloader) Synchronise(id string, hash common.Hash) error {
+func (d *Downloader) synchronise(id string, hash common.Hash) error {
 	// Make sure only one goroutine is ever allowed past this point at once
 	if !atomic.CompareAndSwapInt32(&d.synchronising, 0, 1) {
-		return ErrBusy
+		return errBusy
 	}
 	defer atomic.StoreInt32(&d.synchronising, 0)
 
 	// If the head hash is banned, terminate immediately
 	if d.banned.Has(hash) {
-		return ErrInvalidChain
+		return errInvalidChain
 	}
 	// Post a user notification of the sync (only once per session)
 	if atomic.CompareAndSwapInt32(&d.notified, 0, 1) {
@@ -209,7 +240,7 @@ func (d *Downloader) Synchronise(id string, hash common.Hash) error {
 
 	// Abort if the queue still contains some leftover data
 	if _, cached := d.queue.Size(); cached > 0 && d.queue.GetHeadBlock() != nil {
-		return ErrPendingQueue
+		return errPendingQueue
 	}
 	// Reset the queue and peer set to clean any internal leftover state
 	d.queue.Reset()
@@ -342,7 +373,7 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
 			// Make sure the peer actually gave something valid
 			if len(hashPack.hashes) == 0 {
 				glog.V(logger.Debug).Infof("Peer (%s) responded with empty hash set", active.id)
-				return ErrEmptyHashSet
+				return errEmptyHashSet
 			}
 			for index, hash := range hashPack.hashes {
 				if d.banned.Has(hash) {
@@ -352,7 +383,7 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
 					if err := d.banBlocks(active.id, hash); err != nil {
 						glog.V(logger.Debug).Infof("Failed to ban batch of blocks: %v", err)
 					}
-					return ErrInvalidChain
+					return errInvalidChain
 				}
 			}
 			// Determine if we're done fetching hashes (queue up all pending), and continue if not done
@@ -369,12 +400,12 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
 			inserts := d.queue.Insert(hashPack.hashes)
 			if len(inserts) == 0 && !done {
 				glog.V(logger.Debug).Infof("Peer (%s) responded with stale hashes", active.id)
-				return ErrBadPeer
+				return errBadPeer
 			}
 			if !done {
 				// Check that the peer is not stalling the sync
 				if len(inserts) < MinHashFetch {
-					return ErrStallingPeer
+					return errStallingPeer
 				}
 				// Try and fetch a random block to verify the hash batch
 				// Skip the last hash as the cross check races with the next hash fetch
@@ -408,7 +439,7 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
 			block := blockPack.blocks[0]
 			if check, ok := d.checks[block.Hash()]; ok {
 				if block.ParentHash() != check.parent {
-					return ErrCrossCheckFailed
+					return errCrossCheckFailed
 				}
 				delete(d.checks, block.Hash())
 			}
@@ -418,7 +449,7 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
 			for hash, check := range d.checks {
 				if time.Now().After(check.expire) {
 					glog.V(logger.Debug).Infof("Cross check timeout for %x", hash)
-					return ErrCrossCheckFailed
+					return errCrossCheckFailed
 				}
 			}
 
@@ -438,7 +469,7 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
 			// if all peers have been tried, abort the process entirely or if the hash is
 			// the zero hash.
 			if p == nil || (head == common.Hash{}) {
-				return ErrTimeout
+				return errTimeout
 			}
 			// set p to the active peer. this will invalidate any hashes that may be returned
 			// by our previous (delayed) peer.
@@ -500,7 +531,7 @@ out:
 					peer.SetIdle()
 					glog.V(logger.Detail).Infof("%s: delivered %d blocks", peer, len(blockPack.blocks))
 
-				case ErrInvalidChain:
+				case errInvalidChain:
 					// The hash chain is invalid (blocks are not ordered properly), abort
 					return err
 
@@ -617,7 +648,7 @@ func (d *Downloader) banBlocks(peerId string, head common.Hash) error {
 			return errCancelBlockFetch
 
 		case <-timeout:
-			return ErrTimeout
+			return errTimeout
 
 		case <-d.hashCh:
 			// Out of bounds hashes received, ignore them