From bcd6383f3b51a5904e717fc1939bd25da678fc2f Mon Sep 17 00:00:00 2001
From: nandhh <nandhh@gmail.com>
Date: Mon, 12 Aug 2024 16:50:24 +0800
Subject: [PATCH] feat: enable OP_CAT in tapscript

---
 src/script/interpreter.cpp | 26 ++++++++++++++++++++++++--
 src/script/script.cpp      |  2 +-
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 38bb11aad4..fe68fa4c17 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -451,10 +451,16 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                 if (opcode > OP_16 && ++nOpCount > MAX_OPS_PER_SCRIPT) {
                     return set_error(serror, SCRIPT_ERR_OP_COUNT);
                 }
+
+                // When OP_SUCCESS disabled opcodes (CVE-2010-5137) are
+                // redefined in tapscript, remove them from the if below
+                // and put them here
+                if (opcode == OP_CAT) {
+                    return set_error(serror, SCRIPT_ERR_DISABLED_OPCODE); // Disabled opcodes (CVE-2010-5137).
+                }
             }
 
-            if (opcode == OP_CAT ||
-                opcode == OP_SUBSTR ||
+            if (opcode == OP_SUBSTR ||
                 opcode == OP_LEFT ||
                 opcode == OP_RIGHT ||
                 opcode == OP_INVERT ||
@@ -1213,6 +1219,22 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                 }
                 break;
 
+                //
+                // Byte string operations
+                //
+                case OP_CAT:
+                {
+                    if (stack.size() < 2)
+                        return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
+                    valtype& vch1 = stacktop(-2);
+                    valtype& vch2 = stacktop(-1);
+                    if (vch1.size() + vch2.size() > MAX_SCRIPT_ELEMENT_SIZE)
+                        return set_error(serror, SCRIPT_ERR_PUSH_SIZE);
+                    vch1.insert(vch1.end(), vch2.begin(), vch2.end());
+                    popstack(stack);
+                }
+                break;
+
                 default:
                     return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
             }
diff --git a/src/script/script.cpp b/src/script/script.cpp
index 88b4bc2f44..a177148665 100644
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -334,7 +334,7 @@ bool GetScriptOp(CScriptBase::const_iterator& pc, CScriptBase::const_iterator en
 
 bool IsOpSuccess(const opcodetype& opcode)
 {
-    return opcode == 80 || opcode == 98 || (opcode >= 126 && opcode <= 129) ||
+    return opcode == 80 || opcode == 98 || (opcode >= 127 && opcode <= 129) ||
            (opcode >= 131 && opcode <= 134) || (opcode >= 137 && opcode <= 138) ||
            (opcode >= 141 && opcode <= 142) || (opcode >= 149 && opcode <= 153) ||
            (opcode >= 187 && opcode <= 254);