From 5b75c477841fa463aad9c6e6d95a98b50ce14dd3 Mon Sep 17 00:00:00 2001
From: Andrew Chow <achow101-github@achow101.com>
Date: Tue, 30 May 2017 15:42:10 -0700
Subject: [PATCH] Add a valid opcode sanity check to CScript

Added a function in CScript that checks if the script contains valid opcodes.

Add a test for that function
---
 src/script/script.cpp     | 12 ++++++++++++
 src/script/script.h       |  3 +++
 src/test/script_tests.cpp | 14 ++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/src/script/script.cpp b/src/script/script.cpp
index 70eb8a139..a71fee19c 100644
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -267,3 +267,15 @@ std::string CScriptWitness::ToString() const
     }
     return ret + ")";
 }
+
+bool CScript::HasValidOps() const
+{
+    CScript::const_iterator it = begin();
+    while (it < end()) {
+        opcodetype opcode;
+        if (!GetOp(it, opcode) || opcode > 0xb9) {
+            return false;
+        }
+    }
+    return true;
+}
diff --git a/src/script/script.h b/src/script/script.h
index 95a5999a1..25b80ef62 100644
--- a/src/script/script.h
+++ b/src/script/script.h
@@ -630,6 +630,9 @@ public:
     bool IsPushOnly(const_iterator pc) const;
     bool IsPushOnly() const;
 
+    /** Check if the script contains valid OP_CODES */
+    bool HasValidOps() const;
+
     /**
      * Returns whether the script is guaranteed to fail at execution,
      * regardless of the initial stack. This allows outputs to be pruned
diff --git a/src/test/script_tests.cpp b/src/test/script_tests.cpp
index 343c645cb..70544cacd 100644
--- a/src/test/script_tests.cpp
+++ b/src/test/script_tests.cpp
@@ -1438,4 +1438,18 @@ BOOST_AUTO_TEST_CASE(script_FindAndDelete)
     BOOST_CHECK(s == expect);
 }
 
+BOOST_AUTO_TEST_CASE(script_HasValidOps)
+{
+    // Exercise the HasValidOps functionality
+    CScript script;
+    script = ScriptFromHex("76a9141234567890abcdefa1a2a3a4a5a6a7a8a9a0aaab88ac"); // Normal script
+    BOOST_CHECK(script.HasValidOps());
+    script = ScriptFromHex("76a914ff34567890abcdefa1a2a3a4a5a6a7a8a9a0aaab88ac");
+    BOOST_CHECK(script.HasValidOps());
+    script = ScriptFromHex("ff88ac"); // Script with OP_INVALIDOPCODE explicit
+    BOOST_CHECK(!script.HasValidOps());
+    script = ScriptFromHex("88acc0"); // Script with undefined opcode
+    BOOST_CHECK(!script.HasValidOps());
+}
+
 BOOST_AUTO_TEST_SUITE_END()