From 8a69467982745b481a955bb843aab2cddbd29ca0 Mon Sep 17 00:00:00 2001
From: Jeromy <jeromyj@gmail.com>
Date: Fri, 8 May 2020 10:59:18 -0700
Subject: [PATCH] add some simple sanity checking to incoming blocks in the
 syncer

---
 chain/gen/genesis/genesis.go |  1 +
 chain/sync.go                | 17 ++++++++++++++---
 chain/sync_test.go           | 28 ++++++++++++++++++++++++++++
 chain/types/blockheader.go   |  9 +++++++++
 4 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/chain/gen/genesis/genesis.go b/chain/gen/genesis/genesis.go
index 8e108dcb4..d79696e0f 100644
--- a/chain/gen/genesis/genesis.go
+++ b/chain/gen/genesis/genesis.go
@@ -273,6 +273,7 @@ func MakeGenesisBlock(ctx context.Context, bs bstore.Blockstore, sys runtime.Sys
 		BLSAggregate:          nil,
 		BlockSig:              nil,
 		Timestamp:             template.Timestamp,
+		ElectionProof:         new(types.ElectionProof),
 		BeaconEntries: []types.BeaconEntry{
 			{
 				Round: 0,
diff --git a/chain/sync.go b/chain/sync.go
index e2a78ff46..5a3bf5806 100644
--- a/chain/sync.go
+++ b/chain/sync.go
@@ -88,7 +88,7 @@ type Syncer struct {
 func NewSyncer(sm *stmgr.StateManager, bsync *blocksync.BlockSync, connmgr connmgr.ConnManager, self peer.ID, beacon beacon.RandomBeacon, verifier ffiwrapper.Verifier) (*Syncer, error) {
 	gen, err := sm.ChainStore().GetGenesis()
 	if err != nil {
-		return nil, err
+		return nil, xerrors.Errorf("getting genesis block: %w", err)
 	}
 
 	gent, err := types.NewTipSet([]*types.BlockHeader{gen})
@@ -505,6 +505,14 @@ func (syncer *Syncer) minerIsValid(ctx context.Context, maddr address.Address, b
 
 var ErrTemporal = errors.New("temporal error")
 
+func blockSanityChecks(h *types.BlockHeader) error {
+	if h.ElectionProof == nil {
+		return fmt.Errorf("block cannot have nil election proof")
+	}
+
+	return nil
+}
+
 // Should match up with 'Semantical Validation' in validation.md in the spec
 func (syncer *Syncer) ValidateBlock(ctx context.Context, b *types.FullBlock) error {
 	ctx, span := trace.StartSpan(ctx, "validateBlock")
@@ -513,6 +521,10 @@ func (syncer *Syncer) ValidateBlock(ctx context.Context, b *types.FullBlock) err
 		log.Warn("insecure test validation is enabled, if you see this outside of a test, it is a severe bug!")
 	}
 
+	if err := blockSanityChecks(b.Header); err != nil {
+		return xerrors.Errorf("incoming header failed basic sanity checks: %w", err)
+	}
+
 	h := b.Header
 
 	baseTs, err := syncer.store.LoadTipSet(types.NewTipSetKey(h.Parents...))
@@ -617,8 +629,7 @@ func (syncer *Syncer) ValidateBlock(ctx context.Context, b *types.FullBlock) err
 			return xerrors.Errorf("could not draw randomness: %w", err)
 		}
 
-		err = gen.VerifyVRF(ctx, waddr, vrfBase, h.ElectionProof.VRFProof)
-		if err != nil {
+		if err := gen.VerifyVRF(ctx, waddr, vrfBase, h.ElectionProof.VRFProof); err != nil {
 			return xerrors.Errorf("validating block election proof failed: %w", err)
 		}
 
diff --git a/chain/sync_test.go b/chain/sync_test.go
index 70c3232e2..80310a85f 100644
--- a/chain/sync_test.go
+++ b/chain/sync_test.go
@@ -21,6 +21,7 @@ import (
 	"github.com/filecoin-project/lotus/chain/gen"
 	"github.com/filecoin-project/lotus/chain/store"
 	"github.com/filecoin-project/lotus/chain/types"
+	mocktypes "github.com/filecoin-project/lotus/chain/types/mock"
 	"github.com/filecoin-project/lotus/node"
 	"github.com/filecoin-project/lotus/node/impl"
 	"github.com/filecoin-project/lotus/node/modules"
@@ -511,3 +512,30 @@ func runSyncBenchLength(b *testing.B, l int) {
 
 	tu.waitUntilSync(0, client)
 }
+
+func TestSyncInputs(t *testing.T) {
+	H := 10
+	tu := prepSyncTest(t, H)
+
+	p1 := tu.addClientNode()
+
+	fn := tu.nds[p1].(*impl.FullNodeAPI)
+
+	s := fn.SyncAPI.Syncer
+
+	err := s.ValidateBlock(context.TODO(), &types.FullBlock{
+		Header: &types.BlockHeader{},
+	})
+	if err == nil {
+		t.Fatal("should error on empty block")
+	}
+
+	h := mocktypes.MkBlock(nil, 123, 432)
+
+	h.ElectionProof = nil
+
+	err = s.ValidateBlock(context.TODO(), &types.FullBlock{Header: h})
+	if err == nil {
+		t.Fatal("should error on block with nil election proof")
+	}
+}
diff --git a/chain/types/blockheader.go b/chain/types/blockheader.go
index 86d516f98..adbb13c95 100644
--- a/chain/types/blockheader.go
+++ b/chain/types/blockheader.go
@@ -2,6 +2,7 @@ package types
 
 import (
 	"bytes"
+	"fmt"
 	"math/big"
 
 	"github.com/minio/blake2b-simd"
@@ -101,6 +102,14 @@ func DecodeBlock(b []byte) (*BlockHeader, error) {
 		return nil, err
 	}
 
+	if blk.ElectionProof == nil {
+		return nil, fmt.Errorf("block cannot have nil election proof")
+	}
+
+	if blk.Ticket == nil {
+		return nil, fmt.Errorf("block cannot have nil ticket")
+	}
+
 	return &blk, nil
 }