support allow_ua

[w796933]

Will consider adding support in the future userAgent whitelist ？

[w796933]

sir . how to Prohibit search engine reverse detection ？
Because the dig command is blocking. Resulting in very low efficiency. Site 500 error.

if (string_find(useragent, "Googlebot") or 
	string_find(useragent, "bingbot") or 
	string_find(useragent, "Yahoo") or 
	string_find(useragent, "DuckDuckBot")) then
	
	local getHostname = io.popen("dig -x " .. remote_ip .. " +short")
	local resolvedHostname = getHostname:read("*a")
	getHostname:close()
	
	local getIP = io.popen("getent hosts " .. resolvedHostname)
	local resolvedIP = getIP:read("*a")
	getIP:close()
	
	if (string_find(resolvedHostname, "google.com") or 
		string_find(resolvedHostname, "googlebot.com") or 
		string_find(resolvedHostname, "search.msn.com") or 
		string_find(resolvedHostname, "crawl.yahoo.net") or 
		string_find(resolvedHostname, "duckduckbot.duckduckgo.com")) then