Litecoin: Fix tx parsing related changes in backend 0.21.2, #770

bchain/coins/btc/bitcoinrpc.go

@@ -728,10 +728,10 @@ func (b *BitcoinRPC) GetTransaction(txid string) (*bchain.Tx, error) {
 		return nil, err
 	}
 	tx, err := b.Parser.ParseTxFromJson(r)
-	tx.CoinSpecificData = r
 	if err != nil {
 		return nil, errors.Annotatef(err, "txid %v", txid)
 	}
+	tx.CoinSpecificData = r
 	return tx, nil
 }
 

bchain/coins/litecoin/litecoinparser.go

@@ -1,8 +1,12 @@
 package litecoin
 
 import (
+	"encoding/json"
+
+	"github.com/golang/glog"
 	"github.com/martinboehm/btcd/wire"
 	"github.com/martinboehm/btcutil/chaincfg"
+	"github.com/trezor/blockbook/bchain"
 	"github.com/trezor/blockbook/bchain/coins/btc"
 )
 
@@ -68,3 +72,56 @@ func GetChainParams(chain string) *chaincfg.Params {
 		return &MainNetParams
 	}
 }
+
+// fallbackTx is used to handle situation when Litecoin mainnet returns
+// for certain transactions Version 4294967295 instead of -1, which causes json unmarshal error
+type fallbackTx struct {
+	Hex         string        `json:"hex"`
+	Txid        string        `json:"txid"`
+	Version     uint32        `json:"version"`
+	LockTime    uint32        `json:"locktime"`
+	Vin         []bchain.Vin  `json:"vin"`
+	Vout        []bchain.Vout `json:"vout"`
+	BlockHeight uint32        `json:"blockHeight,omitempty"`
+	// BlockHash     string `json:"blockhash,omitempty"`
+	Confirmations uint32 `json:"confirmations,omitempty"`
+	Time          int64  `json:"time,omitempty"`
+	Blocktime     int64  `json:"blocktime,omitempty"`
+}
+
+// ParseTxFromJson parses JSON message containing transaction and returns Tx struct
+func (p *LitecoinParser) ParseTxFromJson(msg json.RawMessage) (*bchain.Tx, error) {
+	var tx bchain.Tx
+	err := json.Unmarshal(msg, &tx)
+	if err != nil {
+		var fTx fallbackTx
+		fErr := json.Unmarshal(msg, &fTx)
+		// log warning with Txid possibly parsed using fallbackTx
+		glog.Warningf("ParseTxFromJson txid %s to bchain.Tx error %v, using fallback method", fTx.Txid, err)
+		if fErr != nil {
+			return nil, fErr
+		}
+		tx.Hex = fTx.Hex
+		tx.Txid = fTx.Txid
+		tx.Version = int32(fTx.Version)
+		tx.LockTime = fTx.LockTime
+		tx.Vin = fTx.Vin
+		tx.Vout = fTx.Vout
+		tx.BlockHeight = fTx.BlockHeight
+		tx.Confirmations = fTx.Confirmations
+		tx.Time = fTx.Time
+		tx.Blocktime = fTx.Blocktime
+	}
+
+	for i := range tx.Vout {
+		vout := &tx.Vout[i]
+		// convert vout.JsonValue to big.Int and clear it, it is only temporary value used for unmarshal
+		vout.ValueSat, err = p.AmountToBigInt(vout.JsonValue)
+		if err != nil {
+			return nil, err
+		}
+		vout.JsonValue = ""
+	}
+
+	return &tx, nil
+}