From 341bf331c107f894cb771f5c2d925a7f090595a6 Mon Sep 17 00:00:00 2001
From: Martin Boehm <martin.boehm@1mbsoftware.net>
Date: Wed, 9 Jan 2019 23:24:25 +0100
Subject: [PATCH] Add custom handling of unknown input txs during BitcoinType
 block import

---
 bchain/baseparser.go                | 11 +++++++
 bchain/coins/liquid/liquidparser.go | 46 +++++++++++++++++++++++++++--
 bchain/types.go                     |  1 +
 db/rocksdb.go                       |  5 ++--
 4 files changed, 59 insertions(+), 4 deletions(-)

diff --git a/bchain/baseparser.go b/bchain/baseparser.go
index 3060b3c2..10cd7096 100644
--- a/bchain/baseparser.go
+++ b/bchain/baseparser.go
@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/gogo/protobuf/proto"
+	"github.com/golang/glog"
 	"github.com/juju/errors"
 )
 
@@ -26,6 +27,16 @@ func (p *BaseParser) ParseTx(b []byte) (*Tx, error) {
 	return nil, errors.New("ParseTx: not implemented")
 }
 
+// GetAddrDescForUnknownInput returns nil AddressDescriptor
+func (p *BaseParser) GetAddrDescForUnknownInput(block *Block, tx *Tx, input int) AddressDescriptor {
+	var iTxid string
+	if len(tx.Vin) > input {
+		iTxid = tx.Vin[input].Txid
+	}
+	glog.Warningf("height %d, tx %v, input tx %v not found in txAddresses", block.Height, tx.Txid, iTxid)
+	return nil
+}
+
 const zeros = "0000000000000000000000000000000000000000"
 
 // AmountToBigInt converts amount in json.Number (string) to big.Int
diff --git a/bchain/coins/liquid/liquidparser.go b/bchain/coins/liquid/liquidparser.go
index c21e7653..f6758895 100644
--- a/bchain/coins/liquid/liquidparser.go
+++ b/bchain/coins/liquid/liquidparser.go
@@ -3,7 +3,12 @@ package liquid
 import (
 	"blockbook/bchain"
 	"blockbook/bchain/coins/btc"
+	"strconv"
 
+	vlq "github.com/bsm/go-vlq"
+	"github.com/golang/glog"
+
+	"github.com/martinboehm/btcd/txscript"
 	"github.com/martinboehm/btcd/wire"
 	"github.com/martinboehm/btcutil/chaincfg"
 )
@@ -27,15 +32,19 @@ func init() {
 // LiquidParser handle
 type LiquidParser struct {
 	*btc.BitcoinParser
-	baseparser *bchain.BaseParser
+	baseparser                      *bchain.BaseParser
+	origOutputScriptToAddressesFunc btc.OutputScriptToAddressesFunc
 }
 
 // NewLiquidParser returns new LiquidParser instance
 func NewLiquidParser(params *chaincfg.Params, c *btc.Configuration) *LiquidParser {
-	return &LiquidParser{
+	p := &LiquidParser{
 		BitcoinParser: btc.NewBitcoinParser(params, c),
 		baseparser:    &bchain.BaseParser{},
 	}
+	p.origOutputScriptToAddressesFunc = p.OutputScriptToAddressesFunc
+	p.OutputScriptToAddressesFunc = p.outputScriptToAddresses
+	return p
 }
 
 // GetChainParams contains network parameters for the main GameCredits network,
@@ -62,3 +71,36 @@ func (p *LiquidParser) PackTx(tx *bchain.Tx, height uint32, blockTime int64) ([]
 func (p *LiquidParser) UnpackTx(buf []byte) (*bchain.Tx, uint32, error) {
 	return p.baseparser.UnpackTx(buf)
 }
+
+// GetAddrDescForUnknownInput processes inputs that were not found in txAddresses - they are bitcoin transactions
+// create a special script for the input in the form OP_INVALIDOPCODE <txid> <vout varint>
+func (p *LiquidParser) GetAddrDescForUnknownInput(block *bchain.Block, tx *bchain.Tx, input int) bchain.AddressDescriptor {
+	var iTxid string
+	s := make([]byte, 0, 40)
+	if len(tx.Vin) > input {
+		iTxid = tx.Vin[input].Txid
+		btxID, err := p.PackTxid(iTxid)
+		if err == nil {
+			buf := make([]byte, vlq.MaxLen64)
+			l := vlq.PutInt(buf, int64(tx.Vin[input].Vout))
+			s = append(s, txscript.OP_INVALIDOPCODE)
+			s = append(s, btxID...)
+			s = append(s, buf[:l]...)
+		}
+	}
+	glog.Info("height ", block.Height, ", tx ", tx.Txid, ", encountered Bitcoin tx ", iTxid)
+	return s
+}
+
+// outputScriptToAddresses converts ScriptPubKey to bitcoin addresses
+func (p *LiquidParser) outputScriptToAddresses(script []byte) ([]string, bool, error) {
+	// minimum length of the special script OP_INVALIDOPCODE <txid> <index varint> is 34 bytes (1 byte opcode, 32 bytes tx, 1 byte vout)
+	if len(script) > 33 && script[0] == txscript.OP_INVALIDOPCODE {
+		txid, _ := p.UnpackTxid(script[1:33])
+		vout, _ := vlq.Int(script[33:])
+		return []string{
+			"Bitcoin tx " + txid + ":" + strconv.Itoa(int(vout)),
+		}, false, nil
+	}
+	return p.origOutputScriptToAddressesFunc(script)
+}
diff --git a/bchain/types.go b/bchain/types.go
index 293d4e58..e65bada3 100644
--- a/bchain/types.go
+++ b/bchain/types.go
@@ -256,6 +256,7 @@ type BlockChainParser interface {
 	ParseTxFromJson(json.RawMessage) (*Tx, error)
 	PackTx(tx *Tx, height uint32, blockTime int64) ([]byte, error)
 	UnpackTx(buf []byte) (*Tx, uint32, error)
+	GetAddrDescForUnknownInput(block *Block, tx *Tx, input int) AddressDescriptor
 	// blocks
 	PackBlockHash(hash string) ([]byte, error)
 	UnpackBlockHash(buf []byte) (string, error)
diff --git a/db/rocksdb.go b/db/rocksdb.go
index 73c4ad7a..94437caa 100644
--- a/db/rocksdb.go
+++ b/db/rocksdb.go
@@ -13,7 +13,7 @@ import (
 	"strconv"
 	"time"
 
-	"github.com/bsm/go-vlq"
+	vlq "github.com/bsm/go-vlq"
 	"github.com/golang/glog"
 	"github.com/juju/errors"
 	"github.com/tecbot/gorocksdb"
@@ -490,7 +490,8 @@ func (d *RocksDB) processAddressesBitcoinType(block *bchain.Block, addresses add
 					return err
 				}
 				if ita == nil {
-					glog.Warningf("rocksdb: height %d, tx %v, input tx %v not found in txAddresses", block.Height, tx.Txid, input.Txid)
+					// allow parser to process unknown input, some coins may implement special handling, default is to log warning
+					tai.AddrDesc = d.chainParser.GetAddrDescForUnknownInput(block, tx, i)
 					continue
 				}
 				txAddressesMap[stxID] = ita