Check and prevent double registration for blobbers

code/go/0chain.net/blobbercore/handler/protocol.go

@@ -67,6 +67,7 @@ func RegisterBlobber(ctx context.Context) (string, error) {
 
 	time.Sleep(transaction.SLEEP_FOR_TXN_CONFIRMATION * time.Second)
 
+	// initialize storage node (ie blobber)
 	txn, err := transaction.NewTransactionEntity()
 	if err != nil {
 		return "", err
@@ -76,10 +77,21 @@ func RegisterBlobber(ctx context.Context) (string, error) {
 		return "", err
 	}
 
+	// check storage node (ie blobber): is it already registered?
+	sRegisteredNodes, _ := GetBlobbers()
+
+	for _, sRegisteredNode := range sRegisteredNodes {
+		if sn.ID == string(sRegisteredNode.ID) || sn.BaseURL == sRegisteredNode.BaseURL {
+			Logger.Info("Failed during registering blobber to the mining network, it's duplicated")
+			return "", errors.New("Duplicated")
+		}
+	}
+
 	snBytes, err := json.Marshal(sn)
 	if err != nil {
 		return "", err
 	}
+
 	Logger.Info("Adding blobber to the blockchain.")
 	err = txn.ExecuteSmartContract(transaction.STORAGE_CONTRACT_ADDRESS,
 		transaction.ADD_BLOBBER_SC_NAME, string(snBytes), 0)

code/go/0chain.net/blobbercore/handler/zcncore.go

@@ -2,6 +2,7 @@ package handler
 
 import (
 	"sync"
+	"encoding/json"
 
 	"github.com/0chain/gosdk/core/common"
 	"github.com/0chain/gosdk/zcncore"
@@ -11,6 +12,7 @@ type ZCNStatus struct {
 	wg      *sync.WaitGroup
 	success bool
 	balance int64
+	info string
 }
 
 func (zcn *ZCNStatus) OnBalanceAvailable(status int, value int64, info string) {
@@ -23,6 +25,16 @@ func (zcn *ZCNStatus) OnBalanceAvailable(status int, value int64, info string) {
 	zcn.balance = value
 }
 
+func (zcn *ZCNStatus) OnInfoAvailable(op int, status int, info string, err string) {
+	defer zcn.wg.Done()
+	if status == zcncore.StatusSuccess {
+		zcn.success = true
+	} else {
+		zcn.success = false
+	}
+	zcn.info = info
+}
+
 func (zcn *ZCNStatus) OnTransactionComplete(t *zcncore.Transaction, status int) {
 	defer zcn.wg.Done()
 	if status == zcncore.StatusSuccess {
@@ -49,7 +61,7 @@ func CheckBalance() (float64, error) {
 	wg.Add(1)
 	err := zcncore.GetBalance(statusBar)
 	if err != nil {
-		return 0, common.NewError("check_balance_failed", "Call to GetBalance failed with err: "+err.Error())
+		return 0, common.NewError("check_balance_failed", "Call to GetBalance failed with err: " + err.Error())
 	}
 	wg.Wait()
 	if !statusBar.success {
@@ -58,6 +70,32 @@ func CheckBalance() (float64, error) {
 	return zcncore.ConvertToToken(statusBar.balance), nil
 }
 
+func GetBlobbers() ([]*zcncore.Blobber, error) {
+	var info struct {
+		Nodes []*zcncore.Blobber
+	}
+
+	wg := &sync.WaitGroup{}
+	statusBar := &ZCNStatus{wg: wg}
+	wg.Add(1)
+
+	err := zcncore.GetBlobbers(statusBar)
+	if err != nil {
+		return info.Nodes, common.NewError("get_blobbers_failed", "Call to GetBlobbers failed with err: " + err.Error())
+	}
+	wg.Wait()
+
+	if !statusBar.success {
+		return info.Nodes, nil
+	}
+
+	if err = json.Unmarshal([]byte(statusBar.info), &info); err != nil {
+		return info.Nodes, common.NewError("get_blobbers_failed", "Decoding response to GetBlobbers failed with err: " + err.Error())
+	}
+
+	return info.Nodes, nil
+}
+
 func CallFaucet() error {
 	wg := &sync.WaitGroup{}
 	statusBar := &ZCNStatus{wg: wg}