falco/userspace/engine/formats.cpp

/*
Copyright (C) 2016-2018 Draios Inc dba Sysdig.

This file is part of falco.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

*/

#include <json/json.h>

#include "formats.h"
#include "logger.h"
#include "falco_engine.h"


sinsp* falco_formats::s_inspector = NULL;
bool falco_formats::s_json_output = false;
bool falco_formats::s_json_include_output_property = true;
sinsp_evt_formatter_cache *falco_formats::s_formatters = NULL;

const static struct luaL_reg ll_falco [] =
{
	{"formatter", &falco_formats::formatter},
	{"free_formatter", &falco_formats::free_formatter},
	{"free_formatters", &falco_formats::free_formatters},
	{"format_event", &falco_formats::format_event},
	{NULL,NULL}
};

void falco_formats::init(sinsp* inspector, lua_State *ls, bool json_output, bool json_include_output_property)
{
	s_inspector = inspector;
	s_json_output = json_output;
	s_json_include_output_property = json_include_output_property;
	if(!s_formatters)
	{
		s_formatters = new sinsp_evt_formatter_cache(s_inspector);
	}

	luaL_openlib(ls, "formats", ll_falco, 0);
}

int falco_formats::formatter(lua_State *ls)
{
	string format = luaL_checkstring(ls, 1);
	sinsp_evt_formatter* formatter;
	try
	{
		formatter = new sinsp_evt_formatter(s_inspector, format);
		lua_pushlightuserdata(ls, formatter);
	}
	catch(sinsp_exception& e)
	{
		luaL_error(ls, "Invalid output format '%s': '%s'", format.c_str(), e.what());
	}

	return 1;
}

int falco_formats::free_formatter(lua_State *ls)
{
	if (!lua_islightuserdata(ls, -1))
	{
		luaL_error(ls, "Invalid argument passed to free_formatter");
	}

	sinsp_evt_formatter *formatter = (sinsp_evt_formatter *) lua_topointer(ls, 1);

	delete(formatter);

	return 0;
}

int falco_formats::free_formatters(lua_State *ls)
{
	if(s_formatters)
	{
		delete(s_formatters);
		s_formatters = NULL;
	}
	return 0;
}

int falco_formats::format_event (lua_State *ls)
{
	string line;
	string json_line;

	if (!lua_isstring(ls, -1) ||
	    !lua_isstring(ls, -2) ||
	    !lua_isstring(ls, -3) ||
	    !lua_islightuserdata(ls, -4)) {
		lua_pushstring(ls, "Invalid arguments passed to format_event()");
		lua_error(ls);
	}
	sinsp_evt* evt = (sinsp_evt*)lua_topointer(ls, 1);
	const char *rule = (char *) lua_tostring(ls, 2);
	const char *level = (char *) lua_tostring(ls, 3);
	const char *format = (char *) lua_tostring(ls, 4);

	string sformat = format;

	try {
		s_formatters->tostring(evt, sformat, &line);

		if(s_json_output)
		{
			switch(s_inspector->get_buffer_format())
			{
				case sinsp_evt::PF_NORMAL:
					s_inspector->set_buffer_format(sinsp_evt::PF_JSON);
					break;
				case sinsp_evt::PF_EOLS:
					s_inspector->set_buffer_format(sinsp_evt::PF_JSONEOLS);
					break;
				case sinsp_evt::PF_HEX:
					s_inspector->set_buffer_format(sinsp_evt::PF_JSONHEX);
					break;
				case sinsp_evt::PF_HEXASCII:
					s_inspector->set_buffer_format(sinsp_evt::PF_JSONHEXASCII);
					break;
				case sinsp_evt::PF_BASE64:
					s_inspector->set_buffer_format(sinsp_evt::PF_JSONBASE64);
					break;
				default:
					// do nothing
					break;
			}
			s_formatters->tostring(evt, sformat, &json_line);

			// The formatted string might have a leading newline. If it does, remove it.
			if (json_line[0] == '\n')
			{
				json_line.erase(0, 1);
			}
		}
	}
	catch (sinsp_exception& e)
	{
		string err = "Invalid output format '" + sformat + "': '" + string(e.what()) + "'";
		lua_pushstring(ls, err.c_str());
		lua_error(ls);
	}

	// For JSON output, the formatter returned a json-as-text
	// object containing all the fields in the original format
	// message as well as the event time in ns. Use this to build
	// a more detailed object containing the event time, rule,
	// severity, full output, and fields.
	if (s_json_output) {
		Json::Value event;
		Json::FastWriter writer;
		string full_line;

		// Convert the time-as-nanoseconds to a more json-friendly ISO8601.
		time_t evttime = evt->get_ts()/1000000000;
		char time_sec[20]; // sizeof "YYYY-MM-DDTHH:MM:SS"
		char time_ns[12]; // sizeof ".sssssssssZ"
		string iso8601evttime;

		strftime(time_sec, sizeof(time_sec), "%FT%T", gmtime(&evttime));
		snprintf(time_ns, sizeof(time_ns), ".%09luZ", evt->get_ts() % 1000000000);
		iso8601evttime = time_sec;
		iso8601evttime += time_ns;
		event["time"] = iso8601evttime;
		event["rule"] = rule;
		event["priority"] = level;

		if(s_json_include_output_property)
		{
			// This is the filled-in output line.
			event["output"] = line;
		}

		full_line = writer.write(event);

		// Json::FastWriter may add a trailing newline. If it
		// does, remove it.
		if (full_line[full_line.length()-1] == '\n')
		{
			full_line.resize(full_line.length()-1);
		}

		// Cheat-graft the output from the formatter into this
		// string. Avoids an unnecessary json parse just to
		// merge the formatted fields at the object level.
		full_line.pop_back();
		full_line.append(", \"output_fields\": ");
		full_line.append(json_line);
		full_line.append("}");
		line = full_line;
	}

	lua_pushstring(ls, line.c_str());
	return 1;
}