From 98ebcd55eb4a3881ef6153387f5d000c85f3404e Mon Sep 17 00:00:00 2001
From: CryptoManiac <balthazar@yandex.ru>
Date: Sun, 23 Aug 2015 02:27:32 +0300
Subject: [PATCH] VerifyScript

---
 Novacoin/CScript.cs    |    2 +-
 Novacoin/ScriptCode.cs |   68 +++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 68 insertions(+), 2 deletions(-)

diff --git a/Novacoin/CScript.cs b/Novacoin/CScript.cs
index d1165a8..077111f 100644
--- a/Novacoin/CScript.cs
+++ b/Novacoin/CScript.cs
@@ -174,7 +174,7 @@ namespace Novacoin
         /// <summary>
         /// Is it true that script doesn't contain anything except push value operations?
         /// </summary>
-        public bool IsPushonly
+        public bool IsPushOnly
         {
             get
             {
diff --git a/Novacoin/ScriptCode.cs b/Novacoin/ScriptCode.cs
index 0d83bd0..ff8bb40 100644
--- a/Novacoin/ScriptCode.cs
+++ b/Novacoin/ScriptCode.cs
@@ -2020,7 +2020,7 @@ namespace Novacoin
         /// <param name="nIn">Input number</param>
         /// <param name="nHashType">Hashing type flag</param>
         /// <param name="flags">Signature checking flags</param>
-        /// <returns></returns>
+        /// <returns>Checking result</returns>
         public static bool CheckSig(IList<byte> sigBytes, IList<byte> pubkeyBytes, CScript script, CTransaction txTo, int nIn, int nHashType, int flags)
         {
             CPubKey pubkey;
@@ -2070,5 +2070,71 @@ namespace Novacoin
 
             return true;
         }
+
+        /// <summary>
+        /// Evaluates the both scriptSig and scriptPubKey.
+        /// </summary>
+        /// <param name="scriptSig"></param>
+        /// <param name="scriptPubKey"></param>
+        /// <param name="txTo">Transaction</param>
+        /// <param name="nIn">Input number</param>
+        /// <param name="flags">Script validation flags</param>
+        /// <param name="nHashType">Hash type flag</param>
+        /// <returns></returns>
+        public static bool VerifyScript(CScript scriptSig, CScript scriptPubKey, CTransaction txTo, int nIn, int flags, int nHashType)
+        {
+            List<IEnumerable<byte>> stack = new List<IEnumerable<byte>>();
+            List<IEnumerable<byte>> stackCopy = null;
+
+            if (!EvalScript(ref stack, scriptSig, txTo, nIn, flags, nHashType))
+            {
+                return false;
+            }
+
+            if ((flags & (int)scriptflag.SCRIPT_VERIFY_P2SH) != 0)
+            {
+                stackCopy = new List<IEnumerable<byte>> (stack);
+            }
+
+            if (!EvalScript(ref stack, scriptPubKey, txTo, nIn, flags, nHashType))
+            {
+                return false;
+            }
+
+            if (stack.Count == 0 || CastToBool(stack.Last()) == false)
+            {
+                return false;
+            }
+
+            // Additional validation for spend-to-script-hash transactions:
+            if ((flags & (int)scriptflag.SCRIPT_VERIFY_P2SH) != 0 && scriptPubKey.IsPayToScriptHash)
+            {
+                if (!scriptSig.IsPushOnly) // scriptSig must be literals-only
+                {
+                    return false;
+                }
+
+                // stackCopy cannot be empty here, because if it was the
+                // P2SH  HASH <> EQUAL  scriptPubKey would be evaluated with
+                // an empty stack and the EvalScript above would return false.
+
+                if (stackCopy.Count == 0)
+                {
+                    throw new StackMachineException("Fatal script validation error.");
+                }
+
+                CScript pubKey2 = new CScript(stackCopy.Last());
+                popstack(ref stackCopy);
+
+                if (!EvalScript(ref stackCopy, pubKey2, txTo, nIn, flags, nHashType))
+                    return false;
+                if (stackCopy.Count == 0)
+                    return false;
+
+                return CastToBool(stackCopy.Last());
+            }
+
+            return true;
+        }
     };
 }
-- 
1.7.1