Ignore non-existing instances in GetUpdates

Currently GetUpdates returns an error if it is queried for an unknown instance.
This is not correct, as instances can disappear. It should either ignore them,
or return a proof of missing instance. Both is possible, depending on the flag
sent to GetUpdates

byzcoin/api_test.go

@@ -351,47 +351,6 @@ func TestClient_SignerCounterDecoder(t *testing.T) {
 	require.Error(t, c.signerCounterDecoder(buf, &reply))
 }
 
-func TestClient_GetUpdates(t *testing.T) {
-	s := newSer(t, 1, testInterval)
-	defer s.local.CloseAll()
-
-	req := &GetUpdatesRequest{
-		Instances:     nil,
-		Flags:         0,
-		LatestBlockID: nil,
-	}
-	_, err := s.service().GetUpdates(req)
-	require.Error(t, err)
-
-	req.Instances = []IDVersion{{ConfigInstanceID, 0}}
-	req.LatestBlockID = s.genesis.SkipChainID()
-	gur, err := s.service().GetUpdates(req)
-	require.NoError(t, err)
-	require.Equal(t, 0, len(gur.Proofs))
-
-	req.Flags = GUFSendVersion0
-	gur, err = s.service().GetUpdates(req)
-	require.NoError(t, err)
-	require.Equal(t, 1, len(gur.Proofs))
-	require.True(t, gur.Proofs[0].Match(ConfigInstanceID[:]))
-
-	ctx, _ := createConfigTxWithCounter(t, time.Millisecond*100, *s.roster,
-		1e5, s, 1)
-	s.sendTxAndWait(t, ctx, 10)
-
-	req.Flags = 0
-	_, err = s.service().GetUpdates(req)
-	require.Error(t, err)
-	latest, err := s.service().db().GetLatest(s.genesis)
-	req.LatestBlockID = latest.Hash
-	require.NoError(t, err)
-
-	gur, err = s.service().GetUpdates(req)
-	require.NoError(t, err)
-	require.Equal(t, 1, len(gur.Proofs))
-	require.True(t, gur.Proofs[0].Match(ConfigInstanceID[:]))
-}
-
 const testServiceName = "TestByzCoin"
 
 type corruptedService struct {

byzcoin/service.go

@@ -624,17 +624,29 @@ func (s *Service) GetUpdates(pr *GetUpdatesRequest) (*GetUpdatesReply, error) {
 	sendVersion0 := pr.Flags&GUFSendVersion0 > 0
 	reply := &GetUpdatesReply{}
 	for _, idv := range pr.Instances {
-		_, ver, _, _, err := st.GetValues(idv.ID[:])
+		proof, err := st.GetProof(idv.ID[:])
 		if err != nil {
-			return nil, fmt.Errorf("couldn't read values of instance: %v", err)
+			return nil, fmt.Errorf("error while looking up proof: %v", err)
 		}
-		if ver <= idv.Version &&
-			!(sendVersion0 && ver == 0) {
+
+		// Only send missing proofs if flag is set
+		if !proof.Match(idv.ID[:]) {
+			if pr.Flags&GUFSendMissingProofs > 0 {
+				reply.Proofs = append(reply.Proofs, *proof)
+			}
 			continue
 		}
-		proof, err := st.GetProof(idv.ID[:])
+
+		// Check if it's a new version
+		var inst StateChangeBody
+		err = protobuf.Decode(proof.Get(idv.ID[:]), &inst)
 		if err != nil {
-			return nil, fmt.Errorf("error while looking up proof: %v", err)
+			return nil, fmt.Errorf("invalid instance stored in trie: %v",
+				err)
+		}
+		if inst.Version <= idv.Version &&
+			!(sendVersion0 && inst.Version == 0) {
+			continue
 		}
 		reply.Proofs = append(reply.Proofs, *proof)
 	}

byzcoin/service_test.go

@@ -2536,6 +2536,59 @@ func TestService_Repair(t *testing.T) {
 	require.Equal(t, finalRoot, newRoot)
 }
 
+func TestService_GetUpdates(t *testing.T) {
+	s := newSer(t, 1, testInterval)
+	defer s.local.CloseAll()
+
+	req := &GetUpdatesRequest{
+		Instances:     nil,
+		Flags:         0,
+		LatestBlockID: nil,
+	}
+	_, err := s.service().GetUpdates(req)
+	require.Error(t, err)
+
+	req.Instances = []IDVersion{{ConfigInstanceID, 0}}
+	req.LatestBlockID = s.genesis.SkipChainID()
+	gur, err := s.service().GetUpdates(req)
+	require.NoError(t, err)
+	require.Equal(t, 0, len(gur.Proofs))
+
+	req.Flags = GUFSendVersion0
+	gur, err = s.service().GetUpdates(req)
+	require.NoError(t, err)
+	require.Equal(t, 1, len(gur.Proofs))
+	require.True(t, gur.Proofs[0].Match(ConfigInstanceID[:]))
+
+	ctx, _ := createConfigTxWithCounter(t, time.Millisecond*100, *s.roster,
+		1e5, s, 1)
+	s.sendTxAndWait(t, ctx, 10)
+
+	req.Flags = 0
+	_, err = s.service().GetUpdates(req)
+	require.Error(t, err)
+	latest, err := s.service().db().GetLatest(s.genesis)
+	req.LatestBlockID = latest.Hash
+	require.NoError(t, err)
+
+	gur, err = s.service().GetUpdates(req)
+	require.NoError(t, err)
+	require.Equal(t, 1, len(gur.Proofs))
+	require.True(t, gur.Proofs[0].Match(ConfigInstanceID[:]))
+
+	invID := sha256.Sum256([]byte("invalid instance"))
+	req.Instances = append(req.Instances, IDVersion{invID, 0})
+	gur, err = s.service().GetUpdates(req)
+	require.NoError(t, err)
+	require.Equal(t, 1, len(gur.Proofs))
+
+	req.Flags = GUFSendMissingProofs
+	gur, err = s.service().GetUpdates(req)
+	require.NoError(t, err)
+	require.Equal(t, 2, len(gur.Proofs))
+	require.False(t, gur.Proofs[1].Match(invID[:]))
+}
+
 func createBadConfigTx(t *testing.T, s *ser, intervalBad, szBad bool) (ClientTransaction, ChainConfig) {
 	switch {
 	case intervalBad:

byzcoin/struct.go

@@ -725,4 +725,7 @@ const (
 	// GUFSendVersion0 will make GetUpdates to send all instances with
 	// version 0, even those that are note updated.
 	GUFSendVersion0 = GetUpdatesFlags(1 << iota)
+	// GUFSendMissingProofs will make GetUpdates send proofs for missing
+	// instances. If not present, missing instances are ignored.
+	GUFSendMissingProofs
 )