Merge pull request #667 from ava-labs/empty-app-response-handling

Empty app response handling

signature-aggregator/aggregator/aggregator.go

@@ -547,7 +547,7 @@ func (s *SignatureAggregator) isValidSignatureResponse(
 		return blsSignatureBuf{}, false
 	}
 
-	signature, err := s.unmarshalResponse(appResponse.AppBytes)
+	signature, err := s.unmarshalResponse(appResponse.GetAppBytes())
 	if err != nil {
 		s.logger.Error(
 			"Error unmarshaling signature response",
@@ -644,6 +644,10 @@ func (s *SignatureAggregator) marshalRequest(
 }
 
 func (s *SignatureAggregator) unmarshalResponse(responseBytes []byte) (blsSignatureBuf, error) {
+	// empty responses are valid and indicate the node has not seen the message
+	if len(responseBytes) == 0 {
+		return blsSignatureBuf{}, nil
+	}
 	var sigResponse sdk.SignatureResponse
 	err := proto.Unmarshal(responseBytes, &sigResponse)
 	if err != nil {

signature-aggregator/aggregator/aggregator_test.go

@@ -6,6 +6,8 @@ import (
 	"os"
 	"testing"
 
+	"crypto/rand"
+
 	"github.com/ava-labs/avalanchego/ids"
 	"github.com/ava-labs/avalanchego/message"
 	"github.com/ava-labs/avalanchego/proto/pb/sdk"
@@ -346,6 +348,54 @@ func TestCreateSignedMessageSucceeds(t *testing.T) {
 	require.NoError(t, verifyErr)
 }
 
+func TestUnmarshalResponse(t *testing.T) {
+	aggregator, _ := instantiateAggregator(t)
+
+	emptySignatureResponse, err := proto.Marshal(&sdk.SignatureResponse{Signature: []byte{}})
+	require.NoError(t, err)
+
+	randSignature := make([]byte, 96)
+	_, err = rand.Read(randSignature)
+	require.NoError(t, err)
+
+	randSignatureResponse, err := proto.Marshal(&sdk.SignatureResponse{Signature: randSignature})
+	require.NoError(t, err)
+
+	testCases := []struct {
+		name              string
+		appResponseBytes  []byte
+		expectedSignature blsSignatureBuf
+	}{
+		{
+			name:              "empty slice",
+			appResponseBytes:  []byte{},
+			expectedSignature: blsSignatureBuf{},
+		},
+		{
+			name:              "nil slice",
+			appResponseBytes:  nil,
+			expectedSignature: blsSignatureBuf{},
+		},
+		{
+			name:              "empty signature",
+			appResponseBytes:  emptySignatureResponse,
+			expectedSignature: blsSignatureBuf{},
+		},
+		{
+			name:              "random signature",
+			appResponseBytes:  randSignatureResponse,
+			expectedSignature: blsSignatureBuf(randSignature),
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			signature, err := aggregator.unmarshalResponse(tc.appResponseBytes)
+			require.NoError(t, err)
+			require.Equal(t, tc.expectedSignature, signature)
+		})
+	}
+}
+
 type pChainStateStub struct {
 	subnetIDByChainID            map[ids.ID]ids.ID
 	connectedCanonicalValidators *peers.ConnectedCanonicalValidators