Give ScriptInterpreter functions to verify a transaction or single input (#1223)

* Add TxSigCompenent constuctor

* Add verifyInputScript to ScriptInterpreter

* Add tests

core-test/src/test/scala/org/bitcoins/core/script/interpreter/ScriptInterpreterTest.scala

@@ -8,6 +8,7 @@ import org.bitcoins.core.crypto.{
 import org.bitcoins.core.currency.CurrencyUnits
 import org.bitcoins.core.protocol.script._
 import org.bitcoins.core.protocol.transaction.{
+  Transaction,
   TransactionOutput,
   WitnessTransaction
 }
@@ -108,4 +109,31 @@ class ScriptInterpreterTest extends BitcoinSUnitTest {
       }
     }
   }
+
+  it must "evaluate a p2sh witness transaction as valid" in {
+    val p2shWitTx = Transaction(
+      "02000000000101c29e1b0bc7d7eef558cab27731e68526c94a8ee30b5a8795674b39b25430dacd0000000017160014471b19074d141d11042cba016cd60d89caee0150feffffff02ee2916000000000017a91401d95721e723fb9d02fa7ae0d5a330925fa6f90187f0e864da0100000017a9149829ca82bf4d71daeffb14a6b96da4e621cccb31870247304402205406cf034993af5fc0dd9fcd96eafe04acedeb9d4d2a012aa539561cd50b6ce30220680079485226ee184c678da475e291e81ca8b83b5b973d0a8513a5b4a7e24c52012103c6350aad80873966c5a778bc3e019eef399d242ef386e21267652ca1f3e3a6ae087a1900")
+    val prevOut = TransactionOutput(
+      "48677bda0100000017a914885437151ad21f21c5c714ddffdf67e56fcd63ea87")
+
+    ScriptInterpreter.verifyTransaction(p2shWitTx, Vector(prevOut))
+  }
+
+  it must "evaluate a witness transaction as valid" in {
+    val wtx = Transaction(
+      "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")
+    val prevOut = TransactionOutput(
+      "b82a0000000000002200202d501d0b2df21825d3dca7dc2bdaeea2c484c552b4ccbf687ffa887ae47e42c2")
+
+    ScriptInterpreter.verifyTransaction(wtx, Vector(prevOut))
+  }
+
+  it must "evaluate a base transaction as valid" in {
+    val tx = Transaction(
+      "01000000010289c14b991dde643aca30b9010c9b37b8347f3984fa5c31e78adceeea4eefab000000006a47304402206d1ae877e2339ed74a1b203aacdb8e4dc6202f873a228d681d3075f7cd8ef95c022067383abdf0bc1839db0c26a0d77df097d815b4ef086da3872b4a928468b667f30121032fb875942a07a7606933e383c85d688b5fd3482c29035d4289638987582c3f2bffffffff02500e40a10b0000001976a9142301071cf4f2550a705c6348f33e6b33544b768488ac2752fb02000000001976a914741423cca440e7dc81d3468b832433e4db3c924288ac00000000")
+    val prevOut = TransactionOutput(
+      "37733ba40b0000001976a914741423cca440e7dc81d3468b832433e4db3c924288ac")
+
+    ScriptInterpreter.verifyTransaction(tx, Vector(prevOut))
+  }
 }

core/src/main/scala/org/bitcoins/core/crypto/TxSigComponent.scala

@@ -42,6 +42,43 @@ sealed abstract class TxSigComponent {
   def sigVersion: SignatureVersion
 }
 
+object TxSigComponent {
+
+  def apply(
+      transaction: Transaction,
+      inputIndex: UInt32,
+      output: TransactionOutput,
+      flags: Seq[ScriptFlag]): TxSigComponent = {
+    val scriptSig = transaction.inputs(inputIndex.toInt).scriptSignature
+    output.scriptPubKey match {
+      case _: WitnessScriptPubKey =>
+        transaction match {
+          case _: BaseTransaction =>
+            throw new IllegalArgumentException(
+              s"Cannot spend from segwit output ($output) with a base transaction ($transaction)")
+          case wtx: WitnessTransaction =>
+            WitnessTxSigComponent(wtx, inputIndex, output, flags)
+        }
+      case _: P2SHScriptPubKey =>
+        val p2shScriptSig = scriptSig.asInstanceOf[P2SHScriptSignature]
+        if (WitnessScriptPubKey.isWitnessScriptPubKey(
+              p2shScriptSig.redeemScript.asm)) {
+          transaction match {
+            case _: BaseTransaction =>
+              throw new IllegalArgumentException(
+                s"Cannot spend from segwit output ($output) with a base transaction ($transaction)")
+            case wtx: WitnessTransaction =>
+              WitnessTxSigComponentP2SH(wtx, inputIndex, output, flags)
+          }
+        } else {
+          P2SHTxSigComponent(transaction, inputIndex, output, flags)
+        }
+      case _: RawScriptPubKey =>
+        BaseTxSigComponent(transaction, inputIndex, output, flags)
+    }
+  }
+}
+
 /**
   * The [[org.bitcoins.core.crypto.TxSigComponent TxSigComponent]]
   * used to evaluate the the original Satoshi transaction digest algorithm.

core/src/main/scala/org/bitcoins/core/script/interpreter/ScriptInterpreter.scala

@@ -3,6 +3,8 @@ package org.bitcoins.core.script.interpreter
 import org.bitcoins.core.consensus.Consensus
 import org.bitcoins.core.crypto._
 import org.bitcoins.core.currency.{CurrencyUnit, CurrencyUnits}
+import org.bitcoins.core.number.UInt32
+import org.bitcoins.core.policy.Policy
 import org.bitcoins.core.protocol.CompactSizeUInt
 import org.bitcoins.core.protocol.script._
 import org.bitcoins.core.protocol.transaction._
@@ -177,6 +179,32 @@ sealed abstract class ScriptInterpreter extends BitcoinSLogger {
     !programs.exists(p => ScriptInterpreter.run(p) != ScriptOk)
   }
 
+  def verifyInputScript(
+      transaction: Transaction,
+      inputIndex: Long,
+      prevOut: TransactionOutput): Boolean = {
+    val sigComponent = TxSigComponent(
+      transaction,
+      UInt32(inputIndex),
+      prevOut,
+      Policy.standardFlags
+    )
+    ScriptInterpreter.runVerify(PreExecutionScriptProgram(sigComponent))
+  }
+
+  def verifyTransaction(
+      transaction: Transaction,
+      prevOuts: Vector[TransactionOutput]): Boolean = {
+    require(
+      transaction.inputs.size == prevOuts.size,
+      s"There must be a prevOut for every input in the transaction, got ${prevOuts.size}")
+
+    prevOuts.zipWithIndex.forall {
+      case (prevOut, index) =>
+        verifyInputScript(transaction, index, prevOut)
+    }
+  }
+
   /**
     * P2SH scripts are unique in their evaluation, first the scriptSignature must be added to the stack, next the
     * p2sh scriptPubKey must be run to make sure the serialized redeem script hashes to the value found in the p2sh