Remove the clause in Transction.fromHex() where we throw in the case … (#1431)

* Remove the clause in Transction.fromHex() where we throw in the case of a witness transaction, do something smarter and look at bytes in the byte vector

* WIP add test case

* Add back try/catch as it's still necessary for cases of unsigned base transactions

* Add permalink to example test case

core-test/src/test/scala/org/bitcoins/core/protocol/transaction/TransactionTest.scala

@@ -85,6 +85,18 @@ class TransactionTest extends BitcoinSUnitTest {
     tx.hex must be(rawTx)
   }
 
+  it must "deserialize and serialize a base transaction with no inputs" in {
+    //this should be considered a base transaction since there is no script witnesses
+    val hex = "02000000" + //version
+      "0001" + //0 inputs, 1 output
+      "00e1f50500000000" + //1BTC
+      "17a9148fe46e05e329badba1c390a5ea2c0ad7de2059cd87" + //spk
+      "00000000" //locktime
+    val btx = Transaction.fromHex(hex)
+    btx.isInstanceOf[BaseTransaction] must be(true)
+    btx.hex must be(hex)
+  }
+
   it must "serialize and deserialize a large tx" in {
     val rawTx =
       "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"

core/src/main/scala/org/bitcoins/core/protocol/transaction/Transaction.scala

@@ -2,21 +2,10 @@ package org.bitcoins.core.protocol.transaction
 
 import org.bitcoins.core.number.{Int32, UInt32}
 import org.bitcoins.core.protocol.script.ScriptWitness
-import org.bitcoins.core.serializers.transaction.{
-  RawBaseTransactionParser,
-  RawWitnessTransactionParser
-}
-import org.bitcoins.crypto.{
-  CryptoUtil,
-  DoubleSha256Digest,
-  DoubleSha256DigestBE,
-  Factory,
-  NetworkElement
-}
+import org.bitcoins.core.serializers.transaction.{RawBaseTransactionParser, RawWitnessTransactionParser}
+import org.bitcoins.crypto._
 import scodec.bits.ByteVector
 
-import scala.util.{Failure, Success, Try}
-
 /**
   * Created by chris on 7/14/15.
   */
@@ -159,7 +148,7 @@ sealed abstract class WitnessTransaction extends Transaction {
     val base = BaseTransaction(version, inputs, outputs, lockTime)
     base.byteSize * 3 + byteSize
   }
-  override def bytes = RawWitnessTransactionParser.write(this)
+  override def bytes: ByteVector = RawWitnessTransactionParser.write(this)
 
   /**
     * Updates the [[org.bitcoins.core.protocol.script.ScriptWitness ScriptWitness]] at the given index and
@@ -175,14 +164,23 @@ sealed abstract class WitnessTransaction extends Transaction {
 
 object Transaction extends Factory[Transaction] {
 
-  def fromBytes(bytes: ByteVector): Transaction = {
-    val wtxTry = Try(RawWitnessTransactionParser.read(bytes))
-    wtxTry match {
-      case Success(wtx) =>
-        wtx
-      case Failure(_) =>
-        val btx = RawBaseTransactionParser.read(bytes)
-        btx
+  override def fromBytes(bytes: ByteVector): Transaction = {
+    //see BIP141 for marker/flag bytes
+    //https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki#transaction-id
+    if (bytes(4) == WitnessTransaction.marker && bytes(5) == WitnessTransaction.flag) {
+      //this throw/catch is _still_ necessary for the case where we have unsigned base transactions
+      //with zero inputs and 1 output which is serialized as "0001" at bytes 4 and 5.
+      //these transactions will not have a script witness associated with them making them invalid
+      //witness transactions (you need to have a witness to be considered a witness tx)
+      //see: https://github.com/bitcoin-s/bitcoin-s/blob/01d89df1b7c6bc4b1594406d54d5e6019705c654/core-test/src/test/scala/org/bitcoins/core/protocol/transaction/TransactionTest.scala#L88
+      try {
+        RawWitnessTransactionParser.read(bytes)
+      } catch {
+        case scala.util.control.NonFatal(_) =>
+          RawBaseTransactionParser.read(bytes)
+      }
+    } else {
+      RawBaseTransactionParser.read(bytes)
     }
   }
 }
@@ -235,4 +233,12 @@ object WitnessTransaction extends Factory[WitnessTransaction] {
                          EmptyWitness.fromInputs(btx.inputs))
     case wtx: WitnessTransaction => wtx
   }
+
+  val marker: Byte = 0.toByte
+  val flag: Byte = 1.toByte
+
+  /** These bytes -- at index 4 & 5 in a witness transaction -- are used to indicate a witness tx
+    * @see BIP141 https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki#transaction-id
+    * */
+  val witBytes: ByteVector = ByteVector(marker, flag)
 }

core/src/main/scala/org/bitcoins/core/serializers/RawBitcoinSerializer.scala

@@ -1,5 +1,6 @@
 package org.bitcoins.core.serializers
 
+import org.bitcoins.core.util.BitcoinSLogger
 import org.bitcoins.crypto.BytesUtil
 import scodec.bits.ByteVector
 
@@ -7,7 +8,7 @@ import scodec.bits.ByteVector
   * Created by chris on 1/11/16.
   * A common trait for reading/writing bitcoin objects to/from bytes/hex
   */
-abstract class RawBitcoinSerializer[T] {
+abstract class RawBitcoinSerializer[T] extends BitcoinSLogger {
 
   /** Reads a hexadecimal value and transforms it into the native scala type T. */
   def read(hex: String): T = read(BytesUtil.decodeHex(hex))

core/src/main/scala/org/bitcoins/core/serializers/RawBitcoinSerializerHelper.scala

@@ -20,7 +20,7 @@ sealed abstract class RawSerializerHelper {
       bytes: ByteVector,
       constructor: ByteVector => T): (Seq[T], ByteVector) = {
     val count = CompactSizeUInt.parse(bytes)
-    val payload = bytes.splitAt(count.byteSize.toInt)._2
+    val (_,payload) = bytes.splitAt(count.byteSize.toInt)
     var counter = 0
     val b = Vector.newBuilder[T]
     @tailrec

core/src/main/scala/org/bitcoins/core/serializers/transaction/RawWitnessTransactionParser.scala

@@ -68,7 +68,7 @@ sealed abstract class RawWitnessTransactionParser
     //notice we use the old serialization format if all witnesses are empty
     // https://github.com/bitcoin/bitcoin/blob/e8cfe1ee2d01c493b758a67ad14707dca15792ea/src/primitives/transaction.h#L276-L281
     if (tx.witness.exists(_ != EmptyScriptWitness)) {
-      val witConstant = ByteVector(0.toByte, 1.toByte)
+      val witConstant = WitnessTransaction.witBytes
       version ++ witConstant ++ inputs ++ outputs ++ witness ++ lockTime
     } else BaseTransaction(tx.version, tx.inputs, tx.outputs, tx.lockTime).bytes
   }