From 96d9e5800fba31a18f72344068783105b39b3afa Mon Sep 17 00:00:00 2001
From: Ori Newman <orinewman1@gmail.com>
Date: Mon, 23 Nov 2020 08:27:44 -0800
Subject: [PATCH] [NOD-1561] Add TestCheckParentsIncest and fix validation
 order (#1143)

---
 .../blockvalidator/block_header_in_context.go |  5 --
 .../block_header_in_context_test.go           | 70 +++++++++++++++++++
 .../processes/blockvalidator/proof_of_work.go |  9 ++-
 3 files changed, 77 insertions(+), 7 deletions(-)

diff --git a/domain/consensus/processes/blockvalidator/block_header_in_context.go b/domain/consensus/processes/blockvalidator/block_header_in_context.go
index ae52d147a..1d76108ed 100644
--- a/domain/consensus/processes/blockvalidator/block_header_in_context.go
+++ b/domain/consensus/processes/blockvalidator/block_header_in_context.go
@@ -16,11 +16,6 @@ func (v *blockValidator) ValidateHeaderInContext(blockHash *externalapi.DomainHa
 		return err
 	}
 
-	err = v.checkParentsIncest(header)
-	if err != nil {
-		return err
-	}
-
 	isHeadersOnlyBlock, err := v.isHeadersOnlyBlock(blockHash)
 	if err != nil {
 		return err
diff --git a/domain/consensus/processes/blockvalidator/block_header_in_context_test.go b/domain/consensus/processes/blockvalidator/block_header_in_context_test.go
index eea7db5b2..781a15e26 100644
--- a/domain/consensus/processes/blockvalidator/block_header_in_context_test.go
+++ b/domain/consensus/processes/blockvalidator/block_header_in_context_test.go
@@ -81,3 +81,73 @@ func TestValidateMedianTime(t *testing.T) {
 		addBlock(pastMedianTime(tipHash)-1, []*externalapi.DomainHash{tipHash}, ruleerrors.ErrTimeTooOld)
 	})
 }
+
+func TestCheckParentsIncest(t *testing.T) {
+	testutils.ForAllNets(t, true, func(t *testing.T, params *dagconfig.Params) {
+		factory := consensus.NewFactory()
+		tc, teardown, err := factory.NewTestConsensus(params, "TestCheckParentsIncest")
+		if err != nil {
+			t.Fatalf("Error setting up consensus: %+v", err)
+		}
+		defer teardown()
+
+		a, err := tc.AddBlock([]*externalapi.DomainHash{params.GenesisHash}, nil, nil)
+		if err != nil {
+			t.Fatalf("AddBlock: %+v", err)
+		}
+
+		b, err := tc.AddBlock([]*externalapi.DomainHash{a}, nil, nil)
+		if err != nil {
+			t.Fatalf("AddBlock: %+v", err)
+		}
+
+		c, err := tc.AddBlock([]*externalapi.DomainHash{params.GenesisHash}, nil, nil)
+		if err != nil {
+			t.Fatalf("AddBlock: %+v", err)
+		}
+
+		directParentsRelationBlock := &externalapi.DomainBlock{
+			Header: &externalapi.DomainBlockHeader{
+				Version:              0,
+				ParentHashes:         []*externalapi.DomainHash{a, b},
+				HashMerkleRoot:       externalapi.DomainHash{},
+				AcceptedIDMerkleRoot: externalapi.DomainHash{},
+				UTXOCommitment:       externalapi.DomainHash{},
+				TimeInMilliseconds:   0,
+				Bits:                 0,
+				Nonce:                0,
+			},
+			Transactions: nil,
+		}
+
+		err = tc.ValidateAndInsertBlock(directParentsRelationBlock)
+		if !errors.Is(err, ruleerrors.ErrInvalidParentsRelation) {
+			t.Fatalf("unexpected error %+v", err)
+		}
+
+		indirectParentsRelationBlock := &externalapi.DomainBlock{
+			Header: &externalapi.DomainBlockHeader{
+				Version:              0,
+				ParentHashes:         []*externalapi.DomainHash{params.GenesisHash, b},
+				HashMerkleRoot:       externalapi.DomainHash{},
+				AcceptedIDMerkleRoot: externalapi.DomainHash{},
+				UTXOCommitment:       externalapi.DomainHash{},
+				TimeInMilliseconds:   0,
+				Bits:                 0,
+				Nonce:                0,
+			},
+			Transactions: nil,
+		}
+
+		err = tc.ValidateAndInsertBlock(indirectParentsRelationBlock)
+		if !errors.Is(err, ruleerrors.ErrInvalidParentsRelation) {
+			t.Fatalf("unexpected error %+v", err)
+		}
+
+		// Try to add block with unrelated parents
+		_, err = tc.AddBlock([]*externalapi.DomainHash{b, c}, nil, nil)
+		if err != nil {
+			t.Fatalf("AddBlock: %s", err)
+		}
+	})
+}
diff --git a/domain/consensus/processes/blockvalidator/proof_of_work.go b/domain/consensus/processes/blockvalidator/proof_of_work.go
index 49175ffb5..6014a0282 100644
--- a/domain/consensus/processes/blockvalidator/proof_of_work.go
+++ b/domain/consensus/processes/blockvalidator/proof_of_work.go
@@ -15,12 +15,17 @@ func (v *blockValidator) ValidateProofOfWorkAndDifficulty(blockHash *externalapi
 		return err
 	}
 
-	err = v.checkProofOfWork(header)
+	err = v.checkParentsExist(header)
 	if err != nil {
 		return err
 	}
 
-	err = v.checkParentsExist(header)
+	err = v.checkParentsIncest(header)
+	if err != nil {
+		return err
+	}
+
+	err = v.checkProofOfWork(header)
 	if err != nil {
 		return err
 	}