new(grpc): Add tags to outputs service

Signed-off-by: Jason Dellaluce <jasondellaluce@gmail.com>

userspace/engine/falco_engine.cpp

@@ -342,18 +342,30 @@ void falco_engine::populate_rule_result(unique_ptr<struct rule_result> &res, gen
 	if(lua_isfunction(m_ls, -1))
 	{
 		lua_pushnumber(m_ls, ev->get_check_id());
-
-		if(lua_pcall(m_ls, 1, 4, 0) != 0)
+		
+		if(lua_pcall(m_ls, 1, 5, 0) != 0)
 		{
 			const char* lerr = lua_tostring(m_ls, -1);
 			string err = "Error invoking function output: " + string(lerr);
 			throw falco_exception(err);
 		}
-		const char *p =  lua_tostring(m_ls, -4);
+		const char *p =  lua_tostring(m_ls, -5);
 		res->rule = p;
 		res->evt = ev;
-		res->priority_num = (falco_common::priority_type) lua_tonumber(m_ls, -3);
-		res->format = lua_tostring(m_ls, -2);
+		res->priority_num = (falco_common::priority_type) lua_tonumber(m_ls, -4);
+		res->format = lua_tostring(m_ls, -3);
+
+		// Tags are passed back as a table, and is on the top of the stack
+		lua_pushnil(m_ls);  /* first key */
+		while (lua_next(m_ls, -2) != 0) {
+			// key is at index -2, value is at index
+			// -1. We want the value.
+			res->tags.insert(luaL_checkstring(m_ls, -1));
+
+			// Remove value, keep key for next iteration
+			lua_pop(m_ls, 1);
+		}
+		lua_pop(m_ls, 1); // Clean table leftover
 
 		// Exception fields are passed back as a table
 		lua_pushnil(m_ls);  /* first key */

userspace/engine/falco_engine.h

@@ -161,6 +161,7 @@ public:
 		falco_common::priority_type priority_num;
 		std::string format;
 		std::set<std::string> exception_fields;
+		std::set<std::string> tags;
 	};
 
 	//

userspace/engine/lua/rule_loader.lua

@@ -1156,7 +1156,7 @@ function on_event(rule_id)
       error ("rule_loader.on_event(): could not find rule by name: ", rule.rule)
    end
 
-   return rule.rule, rule.priority_num, output, combined_rule.exception_fields
+   return rule.rule, rule.priority_num, output, combined_rule.exception_fields, rule.tags
 end
 
 function print_stats()

userspace/falco/falco.cpp

@@ -374,7 +374,7 @@ uint64_t do_inspect(falco_engine *engine,
 		unique_ptr<falco_engine::rule_result> res = engine->process_sinsp_event(ev);
 		if(res)
 		{
-			outputs->handle_event(res->evt, res->rule, res->source, res->priority_num, res->format);
+			outputs->handle_event(res->evt, res->rule, res->source, res->priority_num, res->format, res->tags);
 		}
 
 		num_evts++;

userspace/falco/falco_outputs.cpp

@@ -142,7 +142,7 @@ void falco_outputs::add_output(falco::outputs::config oc)
 }
 
 void falco_outputs::handle_event(gen_event *evt, string &rule, string &source,
-				 falco_common::priority_type priority, string &format)
+				 falco_common::priority_type priority, string &format, std::set<std::string> tags)
 {
 	if(!m_notifications_tb.claim())
 	{
@@ -192,6 +192,7 @@ void falco_outputs::handle_event(gen_event *evt, string &rule, string &source,
 
 	cmsg.msg = falco_formats::format_event(evt, rule, source, falco_common::priority_names[priority], sformat);
 	cmsg.fields = falco_formats::resolve_tokens(evt, source, sformat);
+	cmsg.tags.insert(tags.begin(), tags.end());
 
 	cmsg.type = ctrl_msg_type::CTRL_MSG_OUTPUT;
 	m_queue.push(cmsg);

userspace/falco/falco_outputs.h

@@ -48,7 +48,7 @@ public:
 
 	// Format then send the event to all configured outputs (`evt` is an event that has matched some rule).
 	void handle_event(gen_event *evt, std::string &rule, std::string &source,
-			  falco_common::priority_type priority, std::string &format);
+			  falco_common::priority_type priority, std::string &format, std::set<std::string> tags);
 
 	// Format then send a generic message to all outputs. Not necessarily associated with any event.
 	void handle_msg(uint64_t now,

userspace/falco/outputs.h

@@ -50,6 +50,7 @@ struct message
 	std::string rule;
 	std::string source;
 	map<std::string, std::string> fields;
+	std::set<std::string> tags;
 };
 
 //

userspace/falco/outputs.proto

@@ -50,6 +50,5 @@ message response {
   string output = 5;
   map<string, string> output_fields = 6;
   string hostname = 7;
-  // TODO(leodido,fntlnz): tags not supported yet, keeping it for reference.
-  // repeated string tags = 8;
+  repeated string tags = 8;
 }

userspace/falco/outputs_grpc.cpp

@@ -64,5 +64,9 @@ void falco::outputs::output_grpc::output(const message *msg)
 	auto host = grpc_res.mutable_hostname();
 	*host = m_hostname;
 
+	// tags
+	auto tags = grpc_res.mutable_tags();
+	*tags = {msg->tags.begin(), msg->tags.end()};
+
 	falco::grpc::queue::get().push(grpc_res);
 }

userspace/falco/webserver.cpp

@@ -102,7 +102,7 @@ bool k8s_audit_handler::accept_data(falco_engine *engine,
 			{
 				outputs->handle_event(res->evt, res->rule,
 						      res->source, res->priority_num,
-						      res->format);
+						      res->format, res->tags);
 			}
 			catch(falco_exception &e)
 			{