[#68] Use unified format for transferX details

Unified format uses transfer type as the first byte
and extra details next. List of transfer types used in
contracts defined in `transfer.go`. It includes:
- mint,
- burn,
- lock,
- unlock,
- container fee.

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

balance/balance_contract.go

@@ -136,7 +136,7 @@ func TransferX(from, to interop.Hash160, amount int, details []byte) bool {
 	return result
 }
 
-func Lock(txID []byte, from, to interop.Hash160, amount, until int) bool {
+func Lock(txDetails []byte, from, to interop.Hash160, amount, until int) bool {
 	ctx := storage.GetContext()
 
 	multiaddr := common.AlphabetAddress()
@@ -151,14 +151,16 @@ func Lock(txID []byte, from, to interop.Hash160, amount, until int) bool {
 	}
 	common.SetSerialized(ctx, to, lockAccount)
 
-	result := token.transfer(ctx, from, to, amount, true, lockTransferMsg)
+	details := common.LockTransferDetails(txDetails)
+
+	result := token.transfer(ctx, from, to, amount, true, details)
 	if !result {
 		// consider using `return false` to remove votes
 		panic("lock: can't lock funds")
 	}
 
 	runtime.Log("lock: created lock account")
-	runtime.Notify("Lock", txID, from, to, amount, until)
+	runtime.Notify("Lock", txDetails, from, to, amount, until)
 
 	return true
 }
@@ -184,15 +186,16 @@ func NewEpoch(epochNum int) bool {
 		}
 
 		if epochNum >= acc.Until {
+			details := common.UnlockTransferDetails(epochNum)
 			// return assets back to the parent
-			token.transfer(ctx, addr, acc.Parent, acc.Balance, true, unlockTransferMsg)
+			token.transfer(ctx, addr, acc.Parent, acc.Balance, true, details)
 		}
 	}
 
 	return true
 }
 
-func Mint(to interop.Hash160, amount int, details []byte) bool {
+func Mint(to interop.Hash160, amount int, txDetails []byte) bool {
 	ctx := storage.GetContext()
 
 	multiaddr := common.AlphabetAddress()
@@ -200,6 +203,8 @@ func Mint(to interop.Hash160, amount int, details []byte) bool {
 		panic("mint: this method must be invoked from inner ring")
 	}
 
+	details := common.MintTransferDetails(txDetails)
+
 	ok := token.transfer(ctx, nil, to, amount, true, details)
 	if !ok {
 		panic("mint: can't transfer assets")
@@ -214,7 +219,7 @@ func Mint(to interop.Hash160, amount int, details []byte) bool {
 	return true
 }
 
-func Burn(from interop.Hash160, amount int, details []byte) bool {
+func Burn(from interop.Hash160, amount int, txDetails []byte) bool {
 	ctx := storage.GetContext()
 
 	multiaddr := common.AlphabetAddress()
@@ -222,6 +227,8 @@ func Burn(from interop.Hash160, amount int, details []byte) bool {
 		panic("burn: this method must be invoked from inner ring")
 	}
 
+	details := common.BurnTransferDetails(txDetails)
+
 	ok := token.transfer(ctx, from, nil, amount, true, details)
 	if !ok {
 		panic("burn: can't transfer assets")

common/transfer.go

@@ -0,0 +1,34 @@
+package common
+
+var (
+	mintPrefix         = []byte{0x01}
+	burnPrefix         = []byte{0x02}
+	lockPrefix         = []byte{0x03}
+	unlockPrefix       = []byte{0x04}
+	containerFeePrefix = []byte{0x10}
+)
+
+func WalletToScriptHash(wallet []byte) []byte {
+	return wallet[1 : len(wallet)-4]
+}
+
+func MintTransferDetails(txDetails []byte) []byte {
+	return append(mintPrefix, txDetails...)
+}
+
+func BurnTransferDetails(txDetails []byte) []byte {
+	return append(burnPrefix, txDetails...)
+}
+
+func LockTransferDetails(txDetails []byte) []byte {
+	return append(lockPrefix, txDetails...)
+}
+
+func UnlockTransferDetails(epoch int) []byte {
+	var buf interface{} = epoch
+	return append(unlockPrefix, buf.([]byte)...)
+}
+
+func ContainerFeeTransferDetails(cid []byte) []byte {
+	return append(containerFeePrefix, cid...)
+}

container/container_contract.go

@@ -50,7 +50,6 @@ const (
 )
 
 var (
-	containerFeeTransferMsg = []byte("container creation fee")
 	eACLPrefix = []byte("eACL")
 )
 
@@ -111,10 +110,11 @@ func Put(container []byte, signature interop.Signature, publicKey interop.Public
 		return true
 	}
 
-	from := walletToScriptHash(ownerID)
+	from := common.WalletToScriptHash(ownerID)
 	netmapContractAddr := storage.Get(ctx, netmapContractKey).(interop.Hash160)
 	balanceContractAddr := storage.Get(ctx, balanceContractKey).(interop.Hash160)
 	containerFee := contract.Call(netmapContractAddr, "config", contract.ReadOnly, containerFeeKey).(int)
+	details := common.ContainerFeeTransferDetails(containerID)
 
 	// todo: check if new container with unique container id
 
@@ -128,7 +128,7 @@ func Put(container []byte, signature interop.Signature, publicKey interop.Public
 			from,
 			to,
 			containerFee,
-			containerFeeTransferMsg, // consider add container id to the message
+			details,
 		)
 		if !tx.(bool) {
 			panic("put: can't transfer assets for container creation")
@@ -454,10 +454,6 @@ func getEACL(ctx storage.Context, cid []byte) extendedACL {
 	return extendedACL{val: []byte{}, sig: interop.Signature{}, pub: interop.PublicKey{}}
 }
 
-func walletToScriptHash(wallet []byte) []byte {
-	return wallet[1 : len(wallet)-4]
-}
-
 func verifySignature(msg []byte, sig interop.Signature, keys []interop.PublicKey) bool {
 	for i := range keys {
 		key := keys[i]
@@ -495,7 +491,7 @@ func isSignedByOwnerKey(msg []byte, sig interop.Signature, owner []byte, key int
 }
 
 func isOwnerFromKey(owner []byte, key interop.PublicKey) bool {
-	ownerSH := walletToScriptHash(owner)
+	ownerSH := common.WalletToScriptHash(owner)
 	keySH := contract.CreateStandardAccount(key)
 
 	return common.BytesEqual(ownerSH, keySH)