-- (C) 2011, Marco Cirillo (LW.Org)
-- Block or restrict by blacklist remote access to local components or hosts.

module:set_global()

local hosts = hosts
local incoming_s2s = prosody.incoming_s2s

local guard_blockall = module:get_option_set("host_guard_blockall", {})
local guard_ball_wl = module:get_option_set("host_guard_blockall_exceptions", {})
local guard_protect = module:get_option_set("host_guard_selective", {})
local guard_block_bl = module:get_option_set("host_guard_blacklist", {})

local config = configmanager
local error_reply = require "util.stanza".error_reply
local tostring = tostring

local function s2s_hook (event)
	local origin, stanza = event.session or event.origin, event.stanza or false
	local to_host, from_host = (not stanza and origin.to_host) or stanza.attr.to, (not stanza and origin.from_host) or stanza.attr.from

	if origin.type == "s2sin" or origin.type == "s2sin_unauthed" then
	   if guard_blockall:contains(to_host) and not guard_ball_wl:contains(from_host) or
	      guard_block_bl:contains(from_host) and guard_protect:contains(to_host) then
                module:log("error", "remote service %s attempted to access restricted host %s", from_host, to_host)
                origin:close({condition = "policy-violation", text = "You're not authorized, good bye."})
                return false
           end
        end

	return nil
end

local function rr_hook (event)
	local from_host, to_host, send, stanza = event.from_host, event.to_host, (event.origin and event.origin.send) or function() end, event.stanza

	if guard_blockall:contains(from_host) and not guard_ball_wl:contains(to_host) or
	   guard_block_bl:contains(to_host) and guard_protect:contains(from_host) then
	     module:log("info", "attempted to connect to a filtered remote host %s", to_host)
	     if stanza.attr.type ~= "error" then send(error_reply(event.stanza, "cancel", "policy-violation", "Communicating with a filtered remote server is not allowed.")) end
	     return true
	end

	return nil
end

local function handle_activation (host, u)
	if guard_blockall:contains(host) or guard_protect:contains(host) then
		if hosts[host] and config.get(host, "core", "authentication") ~= "anonymous" then
			hosts[host].events.add_handler("s2sin-established", s2s_hook, 500)
			hosts[host].events.add_handler("route/remote", rr_hook, 500)
			hosts[host].events.add_handler("stanza/jabber:server:dialback:result", s2s_hook, 500)
                	if not u then
				module:log ("debug", "adding host protection for: "..host)
			else
				module:log ("debug", "updating or adding host protection for: "..host)
			end
		end
	end
end

local function handle_deactivation (host, u, i)
	if guard_blockall:contains(host) or guard_protect:contains(host) then
		if hosts[host] and config.get(host, "core", "authentication") ~= "anonymous" then
			hosts[host].events.remove_handler("s2sin-established", s2s_hook)
			hosts[host].events.remove_handler("route/remote", rr_hook)
			hosts[host].events.remove_handler("stanza/jabber:server:dialback:result", s2s_hook)
                	if not u and not i then module:log ("debug", "removing host protection for: "..host) end
		end
	end
end

local function close_filtered()
	for _, host in pairs(hosts) do
		for name, session in pairs(host.s2sout) do
			if guard_blockall:contains(session.host) and not guard_ball_wl:contains(session.to_host) or
			   guard_block_bl:contains(session.to_host) and guard_protect:contains(session.host) then
				module:log("info", "closing down s2s outgoing stream to filtered entity %s", tostring(session.to_host))
				session:close()
			end
		end
	end
	for session in pairs(incoming_s2s) do
		if session.to_host and session.from_host and
		   (guard_blockall:contains(session.to_host) and not guard_ball_wl:contains(session.from_host) or
		   guard_block_bl:contains(session.from_host) and guard_protect:contains(session.to_host)) then
			module:log("info", "closing down s2s incoming stream from filtered entity %s", tostring(session.from_host))
			session:close()
		end
	end
end

local function init_hosts(u, i)
	for n in pairs(hosts) do
		if guard_blockall:contains(n) or guard_protect:contains(n) then
			handle_deactivation(n, u, i) ; handle_activation(n, u)
		end
	end
	close_filtered()
end

local function reload()
	module:log ("debug", "server configuration reloaded, rehashing plugin tables...")
	guard_blockall = module:get_option_set("host_guard_blockall", {})
	guard_ball_wl = module:get_option_set("host_guard_blockall_exceptions", {})
	guard_protect = module:get_option_set("host_guard_selective", {})
	guard_block_bl = module:get_option_set("host_guard_blacklist", {})

	init_hosts(true)
end

local function setup()
        module:log ("debug", "initializing host guard module...")
        module:hook ("host-activated", handle_activation)
        module:hook ("host-deactivated", handle_deactivation)
        module:hook ("config-reloaded", reload)

        init_hosts(false, true)
end

function module.unload()
	module:log ("debug", "removing host handlers as module is being unloaded...")
	for n in pairs(hosts) do
		hosts[n].events.remove_handler("s2sin-established", s2s_hook)
		hosts[n].events.remove_handler("route/remote", rr_hook)
		hosts[n].events.remove_handler("stanza/jabber:server:dialback:result", s2s_hook)
	end
end

if prosody.start_time then
	setup()
else
	module:hook ("server-started", setup)
end