2022 06 30 OP_CODESEPARATOR impl compatible with taproot (#4439)

* Implement OP_CODESEPARATOR index checking

* Remove taproot serialization options

* Refactor name

Co-authored-by: benthecarman <benthecarman@live.com>

core-test/src/test/scala/org/bitcoins/core/script/ScriptProgramFactoryTest.scala

@@ -73,6 +73,7 @@ class ScriptProgramFactoryTest extends BitcoinSUnitTest {
         altStack = Nil,
         flags = Nil,
         lastCodeSeparator = None,
+        codeSeparatorTapscriptIdx = None,
         conditionalCounter = ConditionalCounter.empty
       )
     inProgress.stack must be(stack)

core/src/main/scala/org/bitcoins/core/script/ScriptProgram.scala

@@ -75,6 +75,7 @@ case class PreExecutionScriptProgram(
       altStack = altStack,
       flags = flags,
       lastCodeSeparator = None,
+      codeSeparatorTapscriptIdx = None,
       conditionalCounter = ConditionalCounter.empty
     )
   }
@@ -221,6 +222,7 @@ case class ExecutionInProgressScriptProgram(
     altStack: List[ScriptToken],
     flags: Seq[ScriptFlag],
     lastCodeSeparator: Option[Int],
+    codeSeparatorTapscriptIdx: Option[Int],
     conditionalCounter: ConditionalCounter)
     extends StartedScriptProgram {
 
@@ -239,6 +241,7 @@ case class ExecutionInProgressScriptProgram(
       altStack,
       flags,
       lastCodeSeparator,
+      codeSeparatorTapscriptIdx,
       errorOpt
     )
   }
@@ -335,6 +338,11 @@ case class ExecutionInProgressScriptProgram(
       newLastCodeSeparator: Int): ExecutionInProgressScriptProgram = {
     this.copy(lastCodeSeparator = Some(newLastCodeSeparator))
   }
+
+  def updateTapscriptCodeSeparatorIdx(
+      newIdx: Int): ExecutionInProgressScriptProgram = {
+    this.copy(codeSeparatorTapscriptIdx = Some(newIdx))
+  }
 }
 
 /** Type for a [[org.bitcoins.core.script.ScriptProgram ScriptProgram]] that has been
@@ -352,6 +360,7 @@ case class ExecutedScriptProgram(
     altStack: List[ScriptToken],
     flags: Seq[ScriptFlag],
     lastCodeSeparator: Option[Int],
+    codeSeparatorTapscriptIdx: Option[Int],
     error: Option[ScriptError])
     extends StartedScriptProgram {
 

core/src/main/scala/org/bitcoins/core/script/crypto/CryptoInterpreter.scala

@@ -124,12 +124,21 @@ sealed abstract class CryptoInterpreter {
     require(program.script.headOption.contains(OP_CODESEPARATOR),
             "Script top must be OP_CODESEPARATOR")
 
+    // Filter out the constants for Tapscript OP_CODESEPARATORs
+    // because we only count op codes
+    val constants =
+      program.originalScript.dropRight(program.script.size).count {
+        case _: ScriptOperation => false
+        case _: ScriptConstant  => true
+      }
+
     val indexOfOpCodeSeparator =
       program.originalScript.size - program.script.size
 
     program
       .updateScript(program.script.tail)
       .updateLastCodeSeparator(indexOfOpCodeSeparator)
+      .updateTapscriptCodeSeparatorIdx(indexOfOpCodeSeparator - constants)
   }
 
   /** Compares the first signature against each public key until it finds an ECDSA match.

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

@@ -469,6 +469,7 @@ sealed abstract class ScriptInterpreter {
               altStack = Nil,
               flags = wTxSigComponent.flags,
               lastCodeSeparator = None,
+              codeSeparatorTapscriptIdx = None,
               error = Some(err)
             )
             Success(program)
@@ -1203,6 +1204,7 @@ sealed abstract class ScriptInterpreter {
         altStack = Nil,
         flags = flags,
         lastCodeSeparator = None,
+        codeSeparatorTapscriptIdx = None,
         error = Some(ScriptErrorDiscourageUpgradeableWitnessProgram)
       )
       Success(executed)