Merge pull request #8 from nspcc-dev/fix/uniq-invocations

Limit ballot lifetime and store unique inner ring invocations

neofs_contract.go

@@ -1,6 +1,7 @@
 package smart_contract
 
 import (
+	"github.com/nspcc-dev/neo-go/pkg/interop/blockchain"
 	"github.com/nspcc-dev/neo-go/pkg/interop/crypto"
 	"github.com/nspcc-dev/neo-go/pkg/interop/engine"
 	"github.com/nspcc-dev/neo-go/pkg/interop/runtime"
@@ -11,8 +12,9 @@ import (
 
 type (
 	ballot struct {
-		id []byte
-		n  int
+		id    []byte   // id of the voting decision
+		n     [][]byte // already voted inner ring nodes
+		block int      // block with the last vote
 	}
 
 	node struct {
@@ -30,6 +32,7 @@ const (
 	innerRingCandidateFee = 100 * 1000 * 1000 // 10^8
 	version               = 1
 	voteKey               = "ballots"
+	blockDiff             = 20 // change base on performance evaluation
 )
 
 func Main(op string, args []interface{}) interface{} {
@@ -198,7 +201,8 @@ func Main(op string, args []interface{}) interface{} {
 		usedList := getSerialized(ctx, "UsedVerifCheckList").([]check)
 		threshold := len(irList)/3*2 + 1
 
-		if !isInnerRingRequest(irList) {
+		irKey := innerRingInvoker(irList)
+		if len(irKey) == 0 {
 			panic("cheque: invoked by non inner ring node")
 		}
 
@@ -207,7 +211,7 @@ func Main(op string, args []interface{}) interface{} {
 			panic("cheque: non unique id")
 		}
 
-		n := vote(ctx, hashID)
+		n := vote(ctx, hashID, irKey)
 		if n >= threshold {
 			removeVotes(ctx, hashID)
 
@@ -238,7 +242,8 @@ func Main(op string, args []interface{}) interface{} {
 		usedList := getSerialized(ctx, "UsedVerifCheckList").([]check)
 		threshold := len(irList)/3*2 + 1
 
-		if !isInnerRingRequest(irList) {
+		irKey := innerRingInvoker(irList)
+		if len(irKey) == 0 {
 			panic("innerRingUpdate: invoked by non inner ring node")
 		}
 
@@ -249,7 +254,7 @@ func Main(op string, args []interface{}) interface{} {
 
 		chequeHash := crypto.Hash256(data)
 
-		n := vote(ctx, chequeHash)
+		n := vote(ctx, chequeHash, irKey)
 		if n >= threshold {
 			removeVotes(ctx, chequeHash)
 
@@ -429,38 +434,54 @@ func delSerializedIR(ctx storage.Context, key string, value []byte) bool {
 	return false
 }
 
-// isInnerRingRequest returns true if contract was invoked by inner ring node.
-func isInnerRingRequest(irList []node) bool {
-	for i := 0; i < len(irList); i++ {
-		irNode := irList[i]
-
-		if runtime.CheckWitness(irNode.pub) {
-			return true
+// innerRingInvoker returns public key of inner ring node that invoked contract.
+func innerRingInvoker(ir []node) []byte {
+	for i := 0; i < len(ir); i++ {
+		node := ir[i]
+		if runtime.CheckWitness(node.pub) {
+			return node.pub
 		}
 	}
 
-	return false
+	return nil
 }
 
-// todo: votes must be from unique inner ring nods
-func vote(ctx storage.Context, id []byte) int {
+func vote(ctx storage.Context, id, from []byte) int {
 	var (
-		newCandidates = []ballot{}
+		newCandidates []ballot
 		candidates    = getSerialized(ctx, voteKey).([]ballot)
 		found         = -1
+		blockHeight   = blockchain.GetHeight()
 	)
 
 	for i := 0; i < len(candidates); i++ {
 		cnd := candidates[i]
 		if util.Equals(cnd.id, id) {
-			cnd = ballot{id: id, n: cnd.n + 1}
-			found = cnd.n
+			voters := cnd.n
+
+			for j := range voters {
+				if util.Equals(voters[j], from) {
+					return len(voters)
+				}
+			}
+
+			voters = append(voters, from)
+			cnd = ballot{id: id, n: voters, block: blockHeight}
+			found = len(voters)
+		}
+
+		// do not add old ballots, they are invalid
+		if blockHeight-cnd.block <= blockDiff {
+			newCandidates = append(newCandidates, cnd)
 		}
-		newCandidates = append(newCandidates, cnd)
 	}
 
 	if found < 0 {
-		newCandidates = append(newCandidates, ballot{id: id, n: 1})
+		voters := [][]byte{from}
+		newCandidates = append(newCandidates, ballot{
+			id:    id,
+			n:     voters,
+			block: blockHeight})
 		found = 1
 	}
 

neofs_contract_test.go

@@ -44,6 +44,7 @@ func TestContract(t *testing.T) {
 	contract := initGoContract(t, contractTemplate, nodeCount)
 
 	plug.cgas[contractStr] = util.Fixed8FromInt64(1000)
+	plug.invokeKey = crypto.MarshalPublicKey(&contract.privs[0].PublicKey)
 
 	var args []interface{}
 	for i := range contract.privs {
@@ -107,6 +108,7 @@ func TestContract(t *testing.T) {
 
 		// call it threshold amount of times
 		for i := 0; i < 2*nodeCount/3+1; i++ {
+			plug.invokeKey = crypto.MarshalPublicKey(&contract.privs[i].PublicKey)
 			v := initVM(contract, plug)
 
 			loadArg(t, v, "Cheque", []interface{}{id, user, int(gas), lockAcc})
@@ -260,6 +262,7 @@ type storagePlugin struct {
 	interops   map[uint32]vm.InteropFunc
 	storageOps []kv
 	notify     []interface{}
+	invokeKey  []byte
 }
 
 func newStoragePlugin(t *testing.T) *storagePlugin {
@@ -290,6 +293,7 @@ func newStoragePlugin(t *testing.T) *storagePlugin {
 	}
 	s.interops[getID("System.ExecutionEngine.GetScriptContainer")] = s.GetScriptContainer
 	s.interops[getID("Neo.Transaction.GetHash")] = s.GetHash
+	s.interops[getID("Neo.Blockchain.GetHeight")] = s.GetHeight
 
 	return s
 }
@@ -402,7 +406,13 @@ func (s *storagePlugin) GetTrigger(v *vm.VM) error {
 }
 
 func (s *storagePlugin) CheckWitness(v *vm.VM) error {
-	v.Estack().PushVal(true)
+	key := v.Estack().Pop().Value().([]byte)
+	if bytes.Equal(key, s.invokeKey) {
+		v.Estack().PushVal(true)
+	} else {
+		v.Estack().PushVal(false)
+	}
+
 	return nil
 }
 
@@ -423,6 +433,11 @@ func (s *storagePlugin) GetHash(v *vm.VM) error {
 	return nil
 }
 
+func (s *storagePlugin) GetHeight(v *vm.VM) error {
+	v.Estack().PushVal(42)
+	return nil
+}
+
 func (s *storagePlugin) logStorage(op string, key, value []byte) {
 	s.storageOps = append(s.storageOps, kv{
 		Operation: op,