From c7ad08c565be04fe2051a1fa95b54855980fedb4 Mon Sep 17 00:00:00 2001
From: whyrusleeping <why@ipfs.io>
Date: Wed, 11 Sep 2019 13:10:29 -0700
Subject: [PATCH] check block signatures during sync

---
 chain/gen/mining.go        |  4 ++--
 chain/sync.go              | 13 +++++++++++++
 chain/types/blockheader.go |  7 +++++++
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/chain/gen/mining.go b/chain/gen/mining.go
index b5f7876e9..4825785c0 100644
--- a/chain/gen/mining.go
+++ b/chain/gen/mining.go
@@ -137,9 +137,9 @@ func MinerCreateBlock(ctx context.Context, sm *stmgr.StateManager, w *wallet.Wal
 
 	// TODO: set timestamp
 
-	nosigbytes, err := next.Serialize()
+	nosigbytes, err := next.SigningBytes()
 	if err != nil {
-		return nil, xerrors.Errorf("failed to serialize block header with no signature: %w", err)
+		return nil, xerrors.Errorf("failed to get signing bytes for block: %w", err)
 	}
 
 	waddr, err := vm.ResolveToKeyAddr(vmi.StateTree(), cst, worker)
diff --git a/chain/sync.go b/chain/sync.go
index d2274dabb..298234d44 100644
--- a/chain/sync.go
+++ b/chain/sync.go
@@ -373,6 +373,15 @@ func (syncer *Syncer) validateTickets(ctx context.Context, mworker address.Addre
 	return nil
 }
 
+func checkBlockSignature(blk *types.BlockHeader, worker address.Address) error {
+	sigb, err := blk.SigningBytes()
+	if err != nil {
+		return xerrors.Errorf("failed to get block signing bytes: %w", err)
+	}
+
+	return blk.BlockSig.Verify(worker, sigb)
+}
+
 // Should match up with 'Semantical Validation' in validation.md in the spec
 func (syncer *Syncer) ValidateBlock(ctx context.Context, b *types.FullBlock) error {
 	h := b.Header
@@ -404,6 +413,10 @@ func (syncer *Syncer) ValidateBlock(ctx context.Context, b *types.FullBlock) err
 		return xerrors.Errorf("GetMinerWorker failed: %w", err)
 	}
 
+	if err := checkBlockSignature(h, waddr); err != nil {
+		return xerrors.Errorf("check block signature failed: %w", err)
+	}
+
 	if err := syncer.validateTickets(ctx, waddr, h.Tickets, baseTs); err != nil {
 		return xerrors.Errorf("validating block tickets failed: %w", err)
 	}
diff --git a/chain/types/blockheader.go b/chain/types/blockheader.go
index f5c078e6b..81556a6e9 100644
--- a/chain/types/blockheader.go
+++ b/chain/types/blockheader.go
@@ -93,6 +93,13 @@ func (blk *BlockHeader) LastTicket() *Ticket {
 	return blk.Tickets[len(blk.Tickets)-1]
 }
 
+func (blk *BlockHeader) SigningBytes() ([]byte, error) {
+	blkcopy := *blk
+	blkcopy.BlockSig = Signature{}
+
+	return blkcopy.Serialize()
+}
+
 type MsgMeta struct {
 	BlsMessages   cid.Cid
 	SecpkMessages cid.Cid