From da08ab9fd81f5ac9f9168652cf175f965db7c8da Mon Sep 17 00:00:00 2001
From: whyrusleeping <why@ipfs.io>
Date: Wed, 9 Oct 2019 17:50:57 +0900
Subject: [PATCH] Implement cache for bad blocks

---
 chain/badtscache.go | 31 +++++++++++++++++++++++++++++++
 chain/sync.go       | 19 ++++++++++++++-----
 2 files changed, 45 insertions(+), 5 deletions(-)
 create mode 100644 chain/badtscache.go

diff --git a/chain/badtscache.go b/chain/badtscache.go
new file mode 100644
index 000000000..9f2cfb1e4
--- /dev/null
+++ b/chain/badtscache.go
@@ -0,0 +1,31 @@
+package chain
+
+import (
+	"sync"
+
+	"github.com/ipfs/go-cid"
+)
+
+type BadBlockCache struct {
+	lk        sync.Mutex
+	badBlocks map[cid.Cid]struct{}
+}
+
+func NewBadBlockCache() *BadBlockCache {
+	return &BadBlockCache{
+		badBlocks: make(map[cid.Cid]struct{}),
+	}
+}
+
+func (bts *BadBlockCache) Add(c cid.Cid) {
+	bts.lk.Lock()
+	defer bts.lk.Unlock()
+	bts.badBlocks[c] = struct{}{}
+}
+
+func (bts *BadBlockCache) Has(c cid.Cid) bool {
+	bts.lk.Lock()
+	defer bts.lk.Unlock()
+	_, ok := bts.badBlocks[c]
+	return ok
+}
diff --git a/chain/sync.go b/chain/sync.go
index 03465f47a..0a3aace6d 100644
--- a/chain/sync.go
+++ b/chain/sync.go
@@ -44,7 +44,7 @@ type Syncer struct {
 	syncLock sync.Mutex
 
 	// TipSets known to be invalid
-	bad BadTipSetCache
+	bad *BadBlockCache
 
 	// handle to the block sync service
 	Bsync *BlockSync
@@ -71,6 +71,7 @@ func NewSyncer(sm *stmgr.StateManager, bsync *BlockSync, self peer.ID) (*Syncer,
 	}
 
 	return &Syncer{
+		bad:       NewBadBlockCache(),
 		Genesis:   gent,
 		Bsync:     bsync,
 		peerHeads: make(map[peer.ID]*types.TipSet),
@@ -80,10 +81,6 @@ func NewSyncer(sm *stmgr.StateManager, bsync *BlockSync, self peer.ID) (*Syncer,
 	}, nil
 }
 
-type BadTipSetCache struct {
-	badBlocks map[cid.Cid]struct{}
-}
-
 const BootstrapPeerThreshold = 1
 
 // InformNewHead informs the syncer about a new potential tipset
@@ -359,6 +356,7 @@ func (syncer *Syncer) ValidateTipSet(ctx context.Context, fts *store.FullTipSet)
 
 	for _, b := range fts.Blocks {
 		if err := syncer.ValidateBlock(ctx, b); err != nil {
+			syncer.bad.Add(b.Cid())
 			return xerrors.Errorf("validating block %s: %w", b.Cid(), err)
 		}
 	}
@@ -610,6 +608,12 @@ func (syncer *Syncer) collectHeaders(ctx context.Context, from *types.TipSet, to
 	// If, for some reason, we have a suffix of the chain locally, handle that here
 	for blockSet[len(blockSet)-1].Height() > untilHeight {
 		log.Warn("syncing local: ", at)
+		for _, bc := range at {
+			if syncer.bad.Has(bc) {
+				return nil, xerrors.Errorf("chain contained block marked previously as bad (%s, %s)", from.Cids(), bc)
+			}
+		}
+
 		ts, err := syncer.store.LoadTipSet(at)
 		if err != nil {
 			if xerrors.Is(err, bstore.ErrNotFound) {
@@ -651,6 +655,11 @@ loop:
 			if b.Height() < untilHeight {
 				break loop
 			}
+			for _, bc := range b.Cids() {
+				if syncer.bad.Has(bc) {
+					return nil, xerrors.Errorf("chain contained block marked previously as bad (%s, %s)", from.Cids(), bc)
+				}
+			}
 			blockSet = append(blockSet, b)
 		}