//Blocks an attempt to connect before even creating our client datum thing.
world/IsBanned(key,address,computer_id)
	if(!key || !address || !computer_id)
		log_access("Failed Login (invalid data): [key] [address]-[computer_id]")
		return list("reason"="invalid login data", "desc"="Error: Could not check ban status, please try again. Error message: Your computer provided invalid or blank information to the server on connection (BYOND Username, IP, and Computer ID). Provided information for reference: Username: '[key]' IP: '[address]' Computer ID: '[computer_id]'. If you continue to get this error, please restart byond or contact byond support.")

	if(text2num(computer_id) == 2147483647) //this cid causes stickybans to go haywire
		log_access("Failed Login (invalid cid): [key] [address]-[computer_id]")
		return list("reason"="invalid login data", "desc"="Error: Could not check ban status, Please try again. Error message: Your computer provided an invalid Computer ID.")
	var/admin = 0
	var/ckey = ckey(key)
	if((ckey in admin_datums) || (ckey in deadmins))
		admin = 1

	//Guest Checking
	if(!guests_allowed && IsGuestKey(key))
		log_access("Failed Login: [key] [computer_id] [address] - Guests not allowed")
		// message_admins("\blue Failed Login: [key] - Guests not allowed")
		return list("reason"="guest", "desc"="\nReason: Guests not allowed. Please sign in with a BYOND account.")

	//check if the IP address is a known Tor node
	if(config.ToRban && ToRban_isbanned(address))
		log_access("Failed Login: [key] [computer_id] [address] - Banned: Tor")
		message_admins("<span class='adminnotice'>Failed Login: [key] - Banned: Tor</span>")
		//ban their computer_id and ckey for posterity
		AddBan(ckey(key), computer_id, "Use of Tor", "Automated Ban", 0, 0)
		var/mistakemessage = ""
		if(config.banappeals)
			mistakemessage = "\nIf you believe this is a mistake, please request help at [config.banappeals]."
		return list("reason"="using Tor", "desc"="\nReason: The network you are using to connect has been banned.[mistakemessage]")


	if(config.ban_legacy_system)
		//Ban Checking
		. = CheckBan(ckey(key), computer_id, address)
		if(.)
			if(admin)
				log_admin("The admin [key] has been allowed to bypass a matching ban on [.["key"]]")
				message_admins("<span class='adminnotice'>The admin [key] has been allowed to bypass a matching ban on [.["key"]]</span>")
				addclientmessage(ckey,"<span class='adminnotice'>You have been allowed to bypass a matching ban on [.["key"]].</span>")
			else
				log_access("Failed Login: [key] [computer_id] [address] - Banned [.["reason"]]")
				return .
	else
		var/ckeytext = ckey(key)

		if(!establish_db_connection())
			log_to_dd("Ban database connection failure. Key [ckeytext] not checked")
			diary << "Ban database connection failure. Key [ckeytext] not checked"
			return

		var/ipquery = ""
		var/cidquery = ""
		if(address)
			ipquery = " OR ip = '[address]' "

		if(computer_id)
			cidquery = " OR computerid = '[computer_id]' "

		var/DBQuery/query = dbcon.NewQuery("SELECT ckey, ip, computerid, a_ckey, reason, expiration_time, duration, bantime, bantype FROM [format_table_name("ban")] WHERE (ckey = '[ckeytext]' [ipquery] [cidquery]) AND (bantype = 'PERMABAN' OR bantype = 'ADMIN_PERMABAN' OR ((bantype = 'TEMPBAN' OR bantype = 'ADMIN_TEMPBAN') AND expiration_time > Now())) AND isnull(unbanned)")

		query.Execute()

		while(query.NextRow())
			var/pckey = query.item[1]
			//var/pip = query.item[2]
			//var/pcid = query.item[3]
			var/ackey = query.item[4]
			var/reason = query.item[5]
			var/expiration = query.item[6]
			var/duration = query.item[7]
			var/bantime = query.item[8]
			var/bantype = query.item[9]
			if(bantype == "ADMIN_PERMABAN" || bantype == "ADMIN_TEMPBAN")
				//admin bans MUST match on ckey to prevent cid-spoofing attacks
				//	as well as dynamic ip abuse
				if(pckey != ckey)
					continue
			if(admin)
				if(bantype == "ADMIN_PERMABAN" || bantype == "ADMIN_TEMPBAN")
					log_admin("The admin [key] is admin banned, and has been disallowed access")
					message_admins("<span class='adminnotice'>The admin [key] is admin banned, and has been disallowed access</span>")
				else
					log_admin("The admin [key] has been allowed to bypass a matching ban on [pckey]")
					message_admins("<span class='adminnotice'>The admin [key] has been allowed to bypass a matching ban on [pckey]</span>")
					addclientmessage(ckey,"<span class='adminnotice'>You have been allowed to bypass a matching ban on [pckey].</span>")
					continue
			var/expires = ""
			if(text2num(duration) > 0)
				expires = " The ban is for [duration] minutes and expires on [expiration] (server time)."
			else
				var/appealmessage = ""
				if(config.banappeals)
					appealmessage = " You may appeal it at <a href='[config.banappeals]'>[config.banappeals]</a>."
				expires = " The is a permanent ban.[appealmessage]"

			var/desc = "\nReason: You, or another user of this computer or connection ([pckey]) is banned from playing here. The ban reason is:\n[reason]\nThis ban was applied by [ackey] on [bantime].[expires]"

			. = list("reason"="[bantype]", "desc"="[desc]")

			log_access("Failed Login: [key] [computer_id] [address] - Banned [.["reason"]]")
			return .

	. = ..()	//default pager ban stuff
	if(.)
		//byond will not trigger isbanned() for "global" host bans,
		//ie, ones where the "apply to this game only" checkbox is not checked (defaults to not checked)
		//So it's safe to let admins walk thru host/sticky bans here
		if(admin)
			log_admin("The admin [key] has been allowed to bypass a matching host/sticky ban")
			message_admins("<span class='adminnotice'>The admin [key] has been allowed to bypass a matching host/sticky ban</span>")
			addclientmessage(ckey,"<span class='adminnotice'>You have been allowed to bypass a matching host/sticky ban.</span>")
			return null
		else
			log_access("Failed Login: [key] [computer_id] [address] - Banned [.["message"]]")

	return .