Parse ERC20 transfer from tx payload data

bchain/coins/eth/erc20.go

@@ -30,7 +30,8 @@ var erc20abi = `[{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"
 {"constant":true,"inputs":[],"name":"version","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function","signature":"0x54fd4d50"}]`
 
 // doing the parsing/processing without using go-ethereum/accounts/abi library, it is simple to get data from Transfer event
-const erc20EventTransferSignature = "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"
+const erc20TransferMethodSignature = "0xa9059cbb"
+const erc20TransferEventSignature = "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"
 const erc20NameSignature = "0x06fdde03"
 const erc20SymbolSignature = "0x95d89b41"
 const erc20DecimalsSignature = "0x313ce567"
@@ -49,7 +50,12 @@ var cachedContractsMux sync.Mutex
 
 func addressFromPaddedHex(s string) (string, error) {
 	var t big.Int
-	_, ok := t.SetString(s, 0)
+	var ok bool
+	if has0xPrefix(s) {
+		_, ok = t.SetString(s[2:], 16)
+	} else {
+		_, ok = t.SetString(s, 16)
+	}
 	if !ok {
 		return "", errors.New("Data is not a number")
 	}
@@ -60,7 +66,7 @@ func addressFromPaddedHex(s string) (string, error) {
 func erc20GetTransfersFromLog(logs []*rpcLog) ([]Erc20Transfer, error) {
 	var r []Erc20Transfer
 	for _, l := range logs {
-		if len(l.Topics) == 3 && l.Topics[0] == erc20EventTransferSignature {
+		if len(l.Topics) == 3 && l.Topics[0] == erc20TransferEventSignature {
 			var t big.Int
 			_, ok := t.SetString(l.Data, 0)
 			if !ok {
@@ -85,6 +91,28 @@ func erc20GetTransfersFromLog(logs []*rpcLog) ([]Erc20Transfer, error) {
 	return r, nil
 }
 
+func erc20GetTransfersFromTx(tx *rpcTransaction) ([]Erc20Transfer, error) {
+	var r []Erc20Transfer
+	if len(tx.Payload) == 128+len(erc20TransferMethodSignature) && strings.HasPrefix(tx.Payload, erc20TransferMethodSignature) {
+		to, err := addressFromPaddedHex(tx.Payload[len(erc20TransferMethodSignature) : 64+len(erc20TransferMethodSignature)])
+		if err != nil {
+			return nil, err
+		}
+		var t big.Int
+		_, ok := t.SetString(tx.Payload[len(erc20TransferMethodSignature)+64:], 16)
+		if !ok {
+			return nil, errors.New("Data is not a number")
+		}
+		r = append(r, Erc20Transfer{
+			Contract: strings.ToLower(tx.To),
+			From:     strings.ToLower(tx.From),
+			To:       strings.ToLower(to),
+			Tokens:   t,
+		})
+	}
+	return r, nil
+}
+
 func (b *EthereumRPC) ethCall(data, to string) (string, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), b.timeout)
 	defer cancel()

bchain/coins/eth/erc20_test.go

@@ -3,6 +3,7 @@
 package eth
 
 import (
+	"blockbook/tests/dbtestdata"
 	fmt "fmt"
 	"math/big"
 	"strings"
@@ -137,3 +138,45 @@ func TestErc20_parseErc20StringProperty(t *testing.T) {
 		})
 	}
 }
+
+func TestErc20_erc20GetTransfersFromTx(t *testing.T) {
+	p := NewEthereumParser(1)
+	b := dbtestdata.GetTestEthereumTypeBlock1(p)
+	bn, _ := new(big.Int).SetString("21e19e0c9bab2400000", 16)
+	tests := []struct {
+		name string
+		args *rpcTransaction
+		want []Erc20Transfer
+	}{
+		{
+			name: "0",
+			args: (b.Txs[0].CoinSpecificData.(completeTransaction)).Tx,
+			want: []Erc20Transfer{},
+		},
+		{
+			name: "1",
+			args: (b.Txs[1].CoinSpecificData.(completeTransaction)).Tx,
+			want: []Erc20Transfer{
+				{
+					Contract: "0x4af4114f73d1c1c903ac9e0361b379d1291808a2",
+					From:     "0x20cd153de35d469ba46127a0c8f18626b59a256a",
+					To:       "0x555ee11fbddc0e49a9bab358a8941ad95ffdb48f",
+					Tokens:   *bn,
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := erc20GetTransfersFromTx(tt.args)
+			if err != nil {
+				t.Errorf("erc20GetTransfersFromTx error = %v", err)
+				return
+			}
+			// the addresses could have different case
+			if strings.ToLower(fmt.Sprint(got)) != strings.ToLower(fmt.Sprint(tt.want)) {
+				t.Errorf("erc20GetTransfersFromTx = %+v, want %+v", got, tt.want)
+			}
+		})
+	}
+}

bchain/coins/eth/ethparser.go

@@ -403,8 +403,12 @@ func GetErc20FromTx(tx *bchain.Tx) ([]Erc20Transfer, error) {
 	var r []Erc20Transfer
 	var err error
 	csd, ok := tx.CoinSpecificData.(completeTransaction)
-	if ok && csd.Receipt != nil {
+	if ok {
-		r, err = erc20GetTransfersFromLog(csd.Receipt.Logs)
+		if csd.Receipt != nil {
+			r, err = erc20GetTransfersFromLog(csd.Receipt.Logs)
+		} else {
+			r, err = erc20GetTransfersFromTx(csd.Tx)
+		}
 		if err != nil {
 			return nil, err
 		}

bchain/coins/eth/ethrpc.go

@@ -430,7 +430,7 @@ func (b *EthereumRPC) getERC20EventsForBlock(blockNumber string) (map[string][]*
 	err := b.rpc.CallContext(ctx, &logs, "eth_getLogs", map[string]interface{}{
 		"fromBlock": blockNumber,
 		"toBlock":   blockNumber,
-		"topics":    []string{erc20EventTransferSignature},
+		"topics":    []string{erc20TransferEventSignature},
 	})
 	if err != nil {
 		return nil, errors.Annotatef(err, "blockNumber %v", blockNumber)