minihttp.lua

--[[
Copyright © 2015 Dynatrace LLC. 
All rights reserved. 
Unpublished rights reserved under the Copyright Laws of the United States.

U.S. GOVERNMENT RIGHTS-Use, duplication, or disclosure by the U.S. Government is
subject to restrictions as set forth in Dynatrace LLC license agreement and as
provided in DFARS 227.7202-1(a) and 227.7202-3(a) (1995), DFARS
252.227-7013(c)(1)(ii) (OCT 1988), FAR 12.212 (a) (1995), FAR 52.227-19, 
or FAR 52.227-14 (ALT III), as applicable.

This product contains confidential information and trade secrets of Dynatrace LLC. 
Disclosure is prohibited without the prior express written permission of Dynatrace LLC. 
Use of this product is subject to the terms and conditions of the user's License Agreement with Dynatrace LLC.
See the license agreement text online at https://community.dynatrace.com/community/download/attachments/5144912/dynaTraceBSD.txt?version=3&modificationDate=1441261477160&api=v2
--]]


package.cpath = package.cpath .. ';./rtmapi/?.so'
require 'amd'

local HTTP_COMMANDS = {'GET', 'POST', 'PUT', 'DELETE', 'CONNECT', 'HEAD'}
local HTTP_PROPERTY = {HOST = 'Host:', USER_AGENT = 'User-Agent:',
	AUTHORIZATION = 'Authorization:', PROXY_AUTHORIZATION = 'Proxy-Authorization:'}
local HTTP_PREFIX = 'http://'
local HTTP_PREFIX_LEN = HTTP_PREFIX:len()
local HTTPS_PREFIX = 'https://'
local HTTPS_PREFIX_LEN = HTTPS_PREFIX:len()
local HTTP = 'HTTP'
local HTTP_LEN = HTTP:len()

local HTTP_STATUS_LEN = 3

local HttpProtoErrorBucket = {NO_BUCKET = 0, CLI_ERR_OTHER_BUCKET = 1, SRV_ERR_OTHER_BUCKET = 2,
	CLI_ERR_UNAUTH_BUCKET = 3, CLI_ERR_NOT_FOUND_BUCKET = 4, CLI_ERR_DEF1_BUCKET = 5,
	SRV_ERR_DEF1_BUCKET = 6, SRV_ERR_DEF2_BUCKET = 7, CLI_ERR_UNAUTH_NO_PASS_BUCKET = 8}

	
-- remove leading and trailing spaces from string s	
local function trim(s)
  return (s:gsub("^%s*(.-)%s*$", "%1"))
end	


-- Returns HTTP command which starts from pstr[offset]
-- If this is not legal command then nil is returned
local function get_http_command(pstr, offset)
	for idx, cmd in ipairs(HTTP_COMMANDS) do
		if pstr:sub(offset, cmd:len()) == cmd then
			return cmd
		end
	end
	return nil
end


local function parse_authorization(pstr, stats)
	local base64_string = pstr:match('Basic (.-)$')
	if base64_string then
		local decoded_string = amd.fromBase64(base64_string)
		if decoded_string then
			local user_name = decoded_string:match('(.-):')
			if user_name then
				stats:setUserName(user_name)
			end
		end
	end
end


-- HTTP request parser
function parse_request(payload, stats)
	if payload:len() == 0 then
		return 0
	end
	-- limit payload to HTTP header:
	local pstart, pend = payload:find("\r\n\r\n") 
	if pend then
		payload = payload:sub(1, pend) 
	end
	local lines_iterator = payload:gmatch("[^\r\n]+")
	local text = lines_iterator()
	if text == nil then
		return 1
	end	
	local cmd = get_http_command(text , 1)
	if cmd == nil then
		print('Lua: This is not a HTTP request')
		--		error(string.format('This is not a HTTP request: %s', payload))
		return 1
	end
	--	print('cmd:', cmd)
	local base_url, idx
	local url_offset = cmd:len() + 1 + 1
	idx = text:find('?', url_offset) or text:find(' ', url_offset)
	if idx ~= nil then
		base_url = text:sub(url_offset, idx - 1)
	end
	local host
	local url_has_host = false
	if base_url:sub(1, 1) ~= '/' then 
		host = text:sub(url_offset):match('([^ /]+)')
		url_has_host = true
	end
	if url_has_host then
		for kk, vv in pairs({HTTP_PREFIX, HTTPS_PREFIX}) do
			if text:find(string.format("%s %s", cmd, vv)) then
				url_has_host = true
				base_url = base_url:sub(vv:len() + 1)
				host = base_url:match('([^ /]+)')
				break
			end
		end
	end
	-- print('base_url:\t"' .. base_url .. '"')
	local properties = {}
	for line in lines_iterator do
		local space_pos = line:find(' ')
		if space_pos ~= nil then
			properties[line:sub(1, space_pos - 1)] = line:sub(space_pos + 1)
		end
	end

	if (not url_has_host) and properties[HTTP_PROPERTY.HOST] then
		host = properties[HTTP_PROPERTY.HOST]
		-- print('host:\t"' .. host .. '"')
		base_url = host .. base_url
	end
	if properties[HTTP_PROPERTY.USER_AGENT] then
		parse_user_agent(properties[HTTP_PROPERTY.USER_AGENT], stats)
	end
	if properties[HTTP_PROPERTY.AUTHORIZATION] then
		parse_authorization(properties[HTTP_PROPERTY.AUTHORIZATION], stats)
	elseif properties[HTTP_PROPERTY.PROXY_AUTHORIZATION] then
		parse_authorization(properties[HTTP_PROPERTY.PROXY_AUTHORIZATION], stats)
	end
	if host ~= nil then
		host = trim(host)
		stats:setOperationName(host, host:len())
	end
	return 0
end


local function handle_http_code(http_response_code, stats)
	if http_response_code == 404 then
		stats:setTransportError(HttpProtoErrorBucket.CLI_ERR_NOT_FOUND_BUCKET)
	elseif (http_response_code == 401) or (http_response_code == 407) then
		stats:setTransportError(HttpProtoErrorBucket.CLI_ERR_UNAUTH_BUCKET)
	elseif (http_response_code >= 400) and (http_response_code < 500) then
		stats:setTransportError(HttpProtoErrorBucket.CLI_ERR_OTHER_BUCKET)
	elseif (http_response_code >= 500) and (http_response_code < 600) then
		stats:setTransportError(HttpProtoErrorBucket.SRV_ERR_OTHER_BUCKET)
	end
end


-- HTTP response parser
function parse_response(payload, stats)
	if payload:len() == 0 then
		return 0
	end
	-- limit payload to HTTP header:
	local pstart, pend = payload:find("\r\n\r\n") 
	if pend then
		payload = payload:sub(1, pend) 
	end	
	local lines_iterator = payload:gmatch("[^\r\n]+")
	local text = lines_iterator()
	if text:sub(1, HTTP_LEN) ~= HTTP then
		print('Lua: This is not a HTTP response')
		return 1
	end
	local space_pos = text:find(' ')
	if space_pos == nil then
		error('Corrupted HTTP response')
		return 1
	else
		local http_code_str = text:sub(space_pos + 1, space_pos + HTTP_STATUS_LEN)
		--		print('"'..http_code_str..'"')
		if http_code_str then
			handle_http_code(tonumber(http_code_str), stats)
		end
	end
	return 0
end


local function set_user_agent_fields(os_name, hardware, browser_name, browser_version, stats)
	stats:setBrowserOsHardware(browser_name, browser_version, os_name, hardware)
end


-- Useful links describing 'User-Agent' field:
-- http://en.wikipedia.org/wiki/User_agent
-- https://developer.mozilla.org/en-US/docs/Gecko_user_agent_string_reference
-- http://msdn.microsoft.com/en-us/library/ms537503%28v=vs.85%29.aspx
-- http://www.useragentstring.com/pages/useragentstring.php
function parse_user_agent(pstr, stats)
	local os_name, browser_name, browser_version, hardware
	os_name, hardware, browser_name, browser_version = pstr:match('%(%w+; (%w+); (%w+) .-(Firefox)/(%S+)')
	if os_name and hardware and browser_name and browser_version then
		set_user_agent_fields(os_name, hardware, browser_name, browser_version, stats)
		return
	end
	browser_name, browser_version, hardware, os_name = pstr:match('%(%w+; (MSIE) (%S+); (%S+) (.[^;%)]+)')
	if os_name and hardware and browser_name and browser_version then
		os_name = string.format("%s %s", hardware, os_name)
		set_user_agent_fields(os_name, hardware, browser_name, browser_version, stats)
		return
	end
	browser_name, browser_version, hardware, os_name = pstr:match('(Opera)/(%S+) %((Windows) ([^;%)]+)')
	if os_name and hardware and browser_name and browser_version then
		os_name = string.format("%s %s", hardware, os_name)
		set_user_agent_fields(os_name, hardware, browser_name, browser_version, stats)
		return
	end
end


local the_module = {}
the_module.parse_request = parse_request
the_module.parse_response = parse_response
return the_module