lua: convert dnp3 to suricata.dnp3 lib

This is an initial 1:1 conversion which is rather simple, as DNP3 only
had one function which converted the whole transaction to a DNP3
table.

Ticket: #7601

src/detect-lua-extensions.c

@@ -556,6 +556,5 @@ int LuaRegisterExtensions(lua_State *lua_state)
     LuaRegisterSshFunctions(lua_state);
     LuaRegisterHasshFunctions(lua_state);
     LuaRegisterSmtpFunctions(lua_state);
-    LuaRegisterDNP3Functions(lua_state);
     return 0;
 }

src/util-lua-builtins.c

@@ -19,6 +19,7 @@
 #include "util-lua-builtins.h"
 #include "util-lua-base64lib.h"
 #include "util-lua-dataset.h"
+#include "util-lua-dnp3.h"
 #include "util-lua-dns.h"
 #include "util-lua-hashlib.h"
 #include "util-lua-packetlib.h"
@@ -28,6 +29,7 @@
 static const luaL_Reg builtins[] = {
     { "suricata.base64", SCLuaLoadBase64Lib },
     { "suricata.dataset", LuaLoadDatasetLib },
+    { "suricata.dnp3", SCLuaLoadDnp3Lib },
     { "suricata.dns", SCLuaLoadDnsLib },
     { "suricata.hashlib", SCLuaLoadHashlib },
     { "suricata.packet", LuaLoadPacketLib },

src/util-lua-dnp3.c

@@ -188,10 +188,15 @@ static int DNP3GetTx(lua_State *luastate)
     return 1;
 }
 
-int LuaRegisterDNP3Functions(lua_State *luastate)
+static const struct luaL_Reg dnp3lib[] = {
+    // clang-format off
+    { "get_tx", DNP3GetTx, },
+    { NULL, NULL, }
+    // clang-format on
+};
+
+int SCLuaLoadDnp3Lib(lua_State *L)
 {
-    lua_pushcfunction(luastate, DNP3GetTx);
+    luaL_newlib(L, dnp3lib);
-    lua_setglobal(luastate, "DNP3GetTx");
+    return 1;
-
-    return 0;
 }

src/util-lua-dnp3.h

@@ -18,6 +18,6 @@
 #ifndef SURICATA_UTIL_LUA_DNP3_H
 #define SURICATA_UTIL_LUA_DNP3_H
 
-int LuaRegisterDNP3Functions(lua_State *);
+int SCLuaLoadDnp3Lib(lua_State *L);
 
 #endif /* !SURICATA_UTIL_LUA_DNP3_H */