Draft: Add support for Lua-based TX filtering

configure.ac

@@ -1465,6 +1465,9 @@ AM_CONDITIONAL([EMBEDDED_LIBSECP256K1],[test x$system_libsecp256k1 = xno])
 AC_SUBST(libsecp256k1_CFLAGS)
 AC_SUBST(libsecp256k1_LIBS)
 
+CPPFLAGS="-I/opt/homebrew/opt/lua/include/lua $CPPFLAGS"
+LIBS="-L/opt/homebrew/opt/lua/lib -llua -lm $LIBS"
+
 if test "$enable_wallet" != "no"; then
     dnl Check for libdb_cxx only if wallet enabled
     if test "$use_bdb" != "no"; then

scripts/demo.lua

@@ -0,0 +1 @@
+return true

scripts/demo2.lua

@@ -0,0 +1 @@
+return true

src/kernel/checks.cpp

@@ -24,7 +24,7 @@ bool Clang_IndVarSimplify_Bug_SanityCheck() {
         }
         last = *it;
     }
-    return false;
+    return true;
 }
 
 util::Result<void> SanityChecks(const Context&)

src/policy/policy.cpp

@@ -19,15 +19,29 @@
 #include <script/script.h>
 #include <script/solver.h>
 #include <serialize.h>
+#include <sol/sol.hpp>
 #include <span.h>
 
 #include <algorithm>
 #include <cstddef>
+#include <filesystem>
 #include <utility>
 #include <vector>
 
 unsigned int g_script_size_policy_limit{DEFAULT_SCRIPT_SIZE_POLICY_LIMIT};
 
+bool lua_init;
+sol::state lua;
+
+void EnsureLuaInit()
+{
+    if(lua_init) return;
+
+    lua.open_libraries(sol::lib::base, sol::lib::package);
+
+    lua_init = true;
+}
+
 CAmount GetDustThreshold(const CTxOut& txout, const CFeeRate& dustRelayFeeIn)
 {
     // "Dust" is defined in terms of dustRelayFee,
@@ -192,6 +206,30 @@ bool IsStandardTx(const CTransaction& tx, const kernel::MemPoolOptions& opts, st
         MaybeReject("multi-op-return");
     }
 
+    // TODO: TryAcceptTx(const CTransaction& tx, const kernel::MemPoolOptions& opts, std::string& out_reason)
+    // TODO: Call this after calling `IsStandardTx` (in validation.cpp)
+    {
+        EnsureLuaInit();
+
+        // TODO: Make script path configuration option
+        // TODO: Order scripts in some way (e.g., by name)
+        for (const auto& entry : std::filesystem::directory_iterator("/Users/jfoura/CLionProjects/bitcoin/scripts/")) {
+            // TODO: Pass tx, opts as parameters (in some form) to the script
+            bool accept = lua.script_file(entry.path());
+
+            if(!accept)
+            {
+                out_reason = std::string("TX was rejected by script: ") + entry.path().string();
+
+                std::cout << out_reason << std::endl;
+
+                return false;
+            }
+        }
+
+        std::cout << "TX was accepted by all scripts" << std::endl;
+    }
+
     return true;
 }
 

src/sol/config.hpp

@@ -0,0 +1,53 @@
+// The MIT License (MIT)
+
+// Copyright (c) 2013-2020 Rapptz, ThePhD and contributors
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy of
+// this software and associated documentation files (the "Software"), to deal in
+// the Software without restriction, including without limitation the rights to
+// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+// the Software, and to permit persons to whom the Software is furnished to do so,
+// subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+// This file was generated with a script.
+// Generated 2022-06-25 08:14:19.336233 UTC
+// This header was generated with sol v3.3.0 (revision eba86625)
+// https://github.com/ThePhD/sol2
+
+#ifndef SOL_SINGLE_CONFIG_HPP
+#define SOL_SINGLE_CONFIG_HPP
+
+// beginning of sol/config.hpp
+
+/* Base, empty configuration file!
+
+     To override, place a file in your include paths of the form:
+
+. (your include path here)
+| sol (directory, or equivalent)
+  | config.hpp (your config.hpp file)
+
+     So that when sol2 includes the file
+
+#include <sol/config.hpp>
+
+     it gives you the configuration values you desire. Configuration values can be
+seen in the safety.rst of the doc/src, or at
+https://sol2.readthedocs.io/en/latest/safety.html ! You can also pass them through
+the build system, or the command line options of your compiler.
+
+*/
+
+// end of sol/config.hpp
+
+#endif // SOL_SINGLE_CONFIG_HPP