add TRC20TransferFrom (#124)

Author: wxf4150

pkg/client/trc20.go

@@ -14,13 +14,14 @@ import (
 )
 
 const (
-	trc20TransferMethodSignature = "0xa9059cbb"
-	trc20ApproveMethodSignature  = "0x095ea7b3"
-	trc20TransferEventSignature  = "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"
-	trc20NameSignature           = "0x06fdde03"
-	trc20SymbolSignature         = "0x95d89b41"
-	trc20DecimalsSignature       = "0x313ce567"
-	trc20BalanceOf               = "0x70a08231"
+	trc20TransferMethodSignature     = "0xa9059cbb"
+	trc20ApproveMethodSignature      = "0x095ea7b3"
+	trc20TransferEventSignature      = "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"
+	trc20NameSignature               = "0x06fdde03"
+	trc20SymbolSignature             = "0x95d89b41"
+	trc20DecimalsSignature           = "0x313ce567"
+	trc20BalanceOf                   = "0x70a08231"
+	trc20TransferFromMethodSignature = "0x23b872dd"
 )
 
 // TRC20Call make cosntant calll
@@ -178,6 +179,26 @@ func (g *GrpcClient) TRC20Send(from, to, contract string, amount *big.Int, feeLi
 	return g.TRC20Call(from, contract, req, false, feeLimit)
 }
 
+/*
+parameter:owner is who will sign the tx
+*/
+func (g *GrpcClient) TRC20TransferFrom(owner, from, to, contract string, amount *big.Int, feeLimit int64) (*api.TransactionExtention, error) {
+	addrA, err := address.Base58ToAddress(from)
+	if err != nil {
+		return nil, err
+	}
+	addrB, err := address.Base58ToAddress(to)
+	if err != nil {
+		return nil, err
+	}
+	ab := common.LeftPadBytes(amount.Bytes(), 32)
+	req := "0x23b872dd" +
+		"0000000000000000000000000000000000000000000000000000000000000000"[len(addrA.Hex())-4:] + addrA.Hex()[4:] +
+		"0000000000000000000000000000000000000000000000000000000000000000"[len(addrB.Hex())-4:] + addrB.Hex()[4:]
+	req += common.Bytes2Hex(ab)
+	return g.TRC20Call(owner, contract, req, false, feeLimit)
+}
+
 // TRC20Approve approve token to address
 func (g *GrpcClient) TRC20Approve(from, to, contract string, amount *big.Int, feeLimit int64) (*api.TransactionExtention, error) {
 	addrB, err := address.Base58ToAddress(to)