Collect "InnerRingUpdate" calls from inner ring nodes

Inner ring nodes do not collect signatures for the cheque now.
Instead they invoke "InnerRingUpdate" method and smart-contract
checks if method was called from inner ring node. Then it
accepts cheque if there were 2/3n+1 invokes.

neofs_contract.go

@@ -8,21 +8,29 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/util"
 )
 
-type node struct {
+type (
+	ballot struct {
+		id []byte
+		n  int
+	}
+
+	node struct {
 		pub []byte
 	}
 
-type check struct {
+	check struct {
 		id     []byte
 		height []byte
 	}
+)
 
+const (
 	// GAS NEP-5 HASH
-const tokenHash = "\x77\xea\x59\x6b\x7a\xdf\x7e\x4d\xd1\x40\x76\x97\x31\xb7\xd2\xf0\xe0\x6b\xcd\x9b"
-
-const innerRingCandidateFee = 100 * 1000 * 1000 // 10^8
-
-const version = 1
+	tokenHash             = "\x77\xea\x59\x6b\x7a\xdf\x7e\x4d\xd1\x40\x76\x97\x31\xb7\xd2\xf0\xe0\x6b\xcd\x9b"
+	innerRingCandidateFee = 100 * 1000 * 1000 // 10^8
+	version               = 1
+	voteKey               = "ballots"
+)
 
 func Main(op string, args []interface{}) interface{} {
 	// The trigger determines whether this smart-contract is being
@@ -75,6 +83,9 @@ func Main(op string, args []interface{}) interface{} {
 		storage.Put(ctx, "UsedVerifCheckList", data)
 		storage.Put(ctx, "InnerRingCandidates", data)
 
+		data = runtime.Serialize([]ballot{})
+		storage.Put(ctx, voteKey, data)
+
 		return true
 	case "InnerRingList":
 		irList := getSerialized(ctx, "InnerRingList").([]node)
@@ -181,23 +192,26 @@ func Main(op string, args []interface{}) interface{} {
 		listSize := listItemCount * 33
 
 		offset := 8 + 2 + listSize
-		msg := data[:offset]
-		message := crypto.SHA256(msg)
 
 		irList := getSerialized(ctx, "InnerRingList").([]node)
-		if !verifySignatures(irList, data, message, offset) {
-			panic("can't verify signatures")
+		usedList := getSerialized(ctx, "UsedVerifCheckList").([]check)
+		threshold := len(irList)/3*2 + 1
+
+		if !isInnerRingRequest(irList) {
+			panic("innerRingUpdate: invoked by non inner ring node")
 		}
 
-		usedList := getSerialized(ctx, "UsedVerifCheckList").([]check)
-		c := check{
-			id:     id,
-			height: []byte{1}, // ir update cheques use height as id
-		}
+		c := check{id: id}
 		if containsCheck(usedList, c) {
-			panic("check has already been used")
+			panic("innerRingUpdate: cheque has non unique id")
 		}
 
+		chequeHash := crypto.Hash256(data)
+
+		n := vote(ctx, chequeHash)
+		if n >= threshold {
+			removeVotes(ctx, chequeHash)
+
 			candidates := getSerialized(ctx, "InnerRingCandidates").([]node)
 			offset = 10
 			newIR := []node{}
@@ -236,6 +250,9 @@ func Main(op string, args []interface{}) interface{} {
 			storage.Put(ctx, "InnerRingList", newIRData)
 			putSerialized(ctx, "UsedVerifCheckList", c)
 
+			runtime.Notify("InnerRingUpdate", c.id, newIRData)
+		}
+
 		return true
 	case "IsInnerRing":
 		if len(args) != 1 {
@@ -405,3 +422,61 @@ func verifySignatures(irList []node, data []byte, message []byte, offset int) bo
 	runtime.Log("not enough verified signatures")
 	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
+		}
+	}
+
+	return false
+}
+
+// todo: votes must be from unique inner ring nods
+func vote(ctx storage.Context, id []byte) int {
+	var (
+		newCandidates = []ballot{}
+		candidates    = getSerialized(ctx, voteKey).([]ballot)
+		found         = -1
+	)
+
+	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
+		}
+		newCandidates = append(newCandidates, cnd)
+	}
+
+	if found < 0 {
+		newCandidates = append(newCandidates, ballot{id: id, n: 1})
+		found = 1
+	}
+
+	data := runtime.Serialize(newCandidates)
+	storage.Put(ctx, voteKey, data)
+
+	return found
+}
+
+func removeVotes(ctx storage.Context, id []byte) {
+	var (
+		newCandidates = []ballot{}
+		candidates    = getSerialized(ctx, voteKey).([]ballot)
+	)
+
+	for i := 0; i < len(candidates); i++ {
+		cnd := candidates[i]
+		if !util.Equals(cnd.id, id) {
+			newCandidates = append(newCandidates, cnd)
+		}
+	}
+
+	data := runtime.Serialize(newCandidates)
+	storage.Put(ctx, voteKey, data)
+}