From b19cb3678f1ecf98beeed014be2bf6663a798f21 Mon Sep 17 00:00:00 2001
From: Leonardo Di Donato <leodidonato@gmail.com>
Date: Mon, 23 Sep 2019 18:48:13 +0000
Subject: [PATCH] fix(userspace/falco): pop output fields lua table and
 correctly check parameters on the stack

Signed-off-by: Leonardo Di Donato <leodidonato@gmail.com>
---
 userspace/engine/formats.cpp      | 30 ++++++++++++------------------
 userspace/falco/falco_outputs.cpp | 26 ++++++++++++++------------
 userspace/falco/lua/output.lua    | 10 ----------
 3 files changed, 26 insertions(+), 40 deletions(-)

diff --git a/userspace/engine/formats.cpp b/userspace/engine/formats.cpp
index 9527c990..bea9e5f0 100644
--- a/userspace/engine/formats.cpp
+++ b/userspace/engine/formats.cpp
@@ -265,17 +265,15 @@ int falco_formats::format_event (lua_State *ls)
 	return 1;
 }
 
-#include <iostream>
-
 int falco_formats::resolve_tokens(lua_State *ls)
 {
-	// if(!lua_isstring(ls, -1) ||
-	//    !lua_isstring(ls, -2) ||
-	//    !lua_islightuserdata(ls, -3))
-	// {
-	// 	lua_pushstring(ls, "Invalid arguments passed to resolve_tokens()");
-	// 	lua_error(ls);
-	// }
+	if(!lua_isstring(ls, -1) ||
+	   !lua_isstring(ls, -2) ||
+	   !lua_islightuserdata(ls, -3))
+	{
+		lua_pushstring(ls, "Invalid arguments passed to resolve_tokens()");
+		lua_error(ls);
+	}
 	gen_event *evt = (gen_event *)lua_topointer(ls, 1);
 	string source = luaL_checkstring(ls, 2);
 	const char *format = (char *)lua_tostring(ls, 3);
@@ -292,19 +290,15 @@ int falco_formats::resolve_tokens(lua_State *ls)
 		json_event_formatter json_formatter(s_engine->json_factory(), sformat);
 		values = json_formatter.tomap((json_event*) evt);
 	}
+	// todo(leodido, fntlnz) > check explicitly for k8s_audit, otherwise throw exception
 
 	lua_newtable(ls);
-	int top = lua_gettop(ls);
-	for(map<string, string>::iterator it = values.begin(); it != values.end(); ++it)
+	for(auto const& v : values)
 	{
-		std::cout << it->first << ":"<< it->second << ", ";
-		const char *key = it->first.c_str();
-		const char *value = it->second.c_str();
-		lua_pushlstring(ls, key, it->first.size());
-		lua_pushlstring(ls, value, it->second.size());
-		lua_settable(ls, top);
+		lua_pushstring(ls, v.first.c_str());
+		lua_pushstring(ls, v.second.c_str());
+		lua_settable(ls, -3);
 	}
-	std::cout << std::endl;
 
 	return 1;
 }
diff --git a/userspace/falco/falco_outputs.cpp b/userspace/falco/falco_outputs.cpp
index 2728d7b7..d248840b 100644
--- a/userspace/falco/falco_outputs.cpp
+++ b/userspace/falco/falco_outputs.cpp
@@ -306,16 +306,17 @@ int falco_outputs::handle_http(lua_State *ls)
 int falco_outputs::handle_grpc(lua_State *ls)
 {
 	// check parameters
-	// if(!lua_isuserdata(ls, 1) ||
-	//    !lua_isstring(ls, 2) ||
-	//    !lua_isstring(ls, 3) ||
-	//    !lua_isstring(ls, 4) ||
-	//    !lua_isstring(ls, 5) ||
-	//    !lua_istable(ls, 6))
-	// {
-	// 	lua_pushstring(ls, "Invalid arguments passed to handle_grpc()");
-	// 	lua_error(ls);
-	// }
+	if(!lua_islightuserdata(ls, -7) ||
+	   !lua_isstring(ls, -6) ||
+	   !lua_isstring(ls, -5) ||
+	   !lua_isstring(ls, -4) ||
+	   !lua_isstring(ls, -3) ||
+	   !lua_istable(ls, -2) ||
+	   !lua_istable(ls, -1))
+	{
+		lua_pushstring(ls, "Invalid arguments passed to handle_grpc()");
+		lua_error(ls);
+	}
 
 	response grpc_res = response();
 
@@ -353,11 +354,12 @@ int falco_outputs::handle_grpc(lua_State *ls)
 	// output fields
 	auto& fields = *grpc_res.mutable_output_fields();
 
-	lua_pushnil(ls);
+	lua_pushnil(ls); // so that lua_next removes it from stack and puts (k, v) on it
 	while (lua_next(ls, 6) != 0) {
 		fields[lua_tostring(ls, -2)] = lua_tostring(ls, -1);
-		lua_pop(ls, 1);
+		lua_pop(ls, 1); // remove value, keep key for lua_next
 	}
+	lua_pop(ls, 1); // pop table
 
 	falco_output_queue::get().push(grpc_res);
 
diff --git a/userspace/falco/lua/output.lua b/userspace/falco/lua/output.lua
index cfa284c8..6a635d35 100644
--- a/userspace/falco/lua/output.lua
+++ b/userspace/falco/lua/output.lua
@@ -216,16 +216,6 @@ function output_event(event, rule, source, priority, priority_num, format)
 
    msg = formats.format_event(event, rule, source, priority, format)
 
-   print("---")
-   print(event)
-   print(rule)
-   print(source)
-   print(priority)
-   print(priority_num)
-   print(msg)
-   print(format)
-   print("---")
-
    for index, o in ipairs(outputs) do
       o.output(event, rule, source, priority, priority_num, msg, format, o.options)
    end