view mod_delegation/mod_delegation.lua @ 4764:a754f7e380b2

mod_dnsupdate: Rewrite port config vs DNS comparison code I'm not sure if it was correct, which means it was hard to understand and thus needed to be simplified. Hope this accomplishes that.
author Kim Alvefur <zash@zash.se>
date Mon, 08 Nov 2021 23:03:14 +0100
parents 679f1834dbdb
children 7d6ae8bb95dc
line wrap: on
line source

-- XEP-0355 (Namespace Delegation)
-- Copyright (C) 2015-2016 Jérôme Poisson
--
-- This module is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.

-- This module manage namespace delegation, a way to delegate server features
-- to an external entity/component. Only the admin mode is implemented so far

-- TODO: client mode

local jid = require("util.jid")
local st = require("util.stanza")
local set = require("util.set")

local new_id = require("util.id").short;

local delegation_session = module:shared("/*/delegation/session")

-- FIXME: temporarily needed for disco_items_hook, to be removed when clean implementation is done
local is_contact_subscribed = require "core.rostermanager".is_contact_subscribed;
local jid_split = require "util.jid".split;
local jid_bare = require "util.jid".bare;

if delegation_session.connected_cb == nil then
	-- set used to have connected event listeners
	-- which allow a host to react on events from
	-- other hosts
	delegation_session.connected_cb = set.new()
end
local connected_cb = delegation_session.connected_cb

local _DELEGATION_NS = 'urn:xmpp:delegation:2'
local _FORWARDED_NS = 'urn:xmpp:forward:0'
local _DISCO_INFO_NS = 'http://jabber.org/protocol/disco#info'
local _DISCO_ITEMS_NS = 'http://jabber.org/protocol/disco#items'
local _DATA_NS = 'jabber:x:data'

local _MAIN_SEP = '::'
local _BARE_SEP = ':bare:'
local _REMAINING = ':*'
local _MAIN_PREFIX = _DELEGATION_NS.._MAIN_SEP
local _BARE_PREFIX = _DELEGATION_NS.._BARE_SEP
local _DISCO_REMAINING = _BARE_PREFIX.."disco#info".._REMAINING
local _DISCO_ITEMS_REMAINING = _BARE_PREFIX.."disco#items".._REMAINING
local _PREFIXES = {_MAIN_PREFIX, _BARE_PREFIX}

local disco_nest

module:log("debug", "Loading namespace delegation module ")

--> Configuration management <--

local ns_delegations = module:get_option("delegations", {})

local jid2ns = {}
for namespace, ns_data in pairs(ns_delegations) do
	-- "connected" contain the full jid of connected managing entity
	ns_data.connected = nil
	if ns_data.jid then
		if jid2ns[ns_data.jid] == nil then
			jid2ns[ns_data.jid] = {}
		end
		jid2ns[ns_data.jid][namespace] = ns_data
		module:log("debug", "Namespace %s is delegated%s to %s", namespace, ns_data.filtering and " (with filtering)" or "", ns_data.jid)
	else
		module:log("warn", "Ignoring delegation for %s: no jid specified", tostring(namespace))
		ns_delegations[namespace] = nil
	end
end


local function advertise_delegations(session, to_jid)
	-- send <message/> stanza to advertise delegations
	-- as expained in § 4.2
	local message = st.message({from=module.host, to=to_jid})
					  :tag("delegation", {xmlns=_DELEGATION_NS})

	-- we need to check if a delegation is granted because the configuration
	-- can be complicated if some delegations are granted to bare jid
	-- and other to full jids, and several resources are connected.
	local have_delegation = false

	for namespace, ns_data  in pairs(jid2ns[to_jid]) do
		if ns_data.connected == to_jid then
			have_delegation = true
			message:tag("delegated", {namespace=namespace})
			if type(ns_data.filtering) == "table" then
				for _, attribute in pairs(ns_data.filtering) do
					message:tag("attribute", {name=attribute}):up()
				end
			end
			message:up()
		end
	end

	if have_delegation then
		session.send(message)
	end
end

local function set_connected(entity_jid)
	-- set the "connected" key for all namespace managed by entity_jid
	-- if the namespace has already a connected entity, ignore the new one
	local function set_config(jid_)
		for namespace, ns_data in pairs(jid2ns[jid_]) do
			if ns_data.connected == nil then
				ns_data.connected = entity_jid
				-- disco remaining and disco items remaining are special namespaces
				-- there is no disco nesting for them
				if namespace ~= _DISCO_ITEMS_REMAINING and namespace ~= _DISCO_REMAINING then
					disco_nest(namespace, entity_jid)
				end
			end
		end
	end
	local bare_jid = jid.bare(entity_jid)
	set_config(bare_jid)
	-- We can have a bare jid of a full jid specified in configuration
	-- so we try our luck with both (first connected resource will
	-- manage the namespaces in case of bare jid)
	if bare_jid ~= entity_jid then
		set_config(entity_jid)
		jid2ns[entity_jid] = jid2ns[bare_jid]
	end
end

local function on_presence(event)
	local session = event.origin
	local bare_jid = jid.bare(session.full_jid)

	if jid2ns[bare_jid] or jid2ns[session.full_jid] then
		set_connected(session.full_jid)
		advertise_delegations(session, session.full_jid)
	end
end

local function on_component_connected(event)
	-- method called by the module loaded by the component
	-- /!\ the event come from the component host,
	-- not from the host of this module
	local session = event.session
	local bare_jid = jid.join(session.username, session.host)

	local jid_delegations = jid2ns[bare_jid]
	if jid_delegations ~= nil then
		set_connected(bare_jid)
		advertise_delegations(session, bare_jid)
	end
end

local function on_component_auth(event)
	-- react to component-authenticated event from this host
	-- and call the on_connected methods from all other hosts
	-- needed for the component to get delegations advertising
	for callback in connected_cb:items() do
		callback(event)
	end
end

if module:get_host_type() ~= "component" then
	connected_cb:add(on_component_connected)
end
module:hook('component-authenticated', on_component_auth)
module:hook('presence/initial', on_presence)


--> delegated namespaces hook <--

local managing_ent_error
local stanza_cache = {} -- we cache original stanza to build reply

local function managing_ent_result(event)
	-- this function manage iq results from the managing entity
	-- it do a couple of security check before sending the
	-- result to the managed entity
	local stanza = event.stanza
	if stanza.attr.to ~= module.host then
		module:log("warn", 'forwarded stanza result has "to" attribute not addressed to current host, id conflict ?')
		return
	end
	module:unhook("iq-result/host/"..stanza.attr.id, managing_ent_result)
	module:unhook("iq-error/host/"..stanza.attr.id, managing_ent_error)

	-- lot of checks to do...
	local delegation = stanza.tags[1]
	if #stanza ~= 1 or delegation.name ~= "delegation" or
		delegation.attr.xmlns ~= _DELEGATION_NS then
		module:log("warn", "ignoring invalid iq result from managing entity %s", stanza.attr.from)
		stanza_cache[stanza.attr.from][stanza.attr.id] = nil
		return true
	end

	local forwarded = delegation.tags[1]
	if #delegation ~= 1 or forwarded.name ~= "forwarded" or
		forwarded.attr.xmlns ~= _FORWARDED_NS then
		module:log("warn", "ignoring invalid iq result from managing entity %s", stanza.attr.from)
		stanza_cache[stanza.attr.from][stanza.attr.id] = nil
		return true
	end

	local iq = forwarded.tags[1]
	if #forwarded ~= 1 or iq.name ~= "iq" or
		iq.attr.xmlns ~= 'jabber:client' or
		(iq.attr.type =='result' and #iq > 1) or
		(iq.attr.type == 'error' and #iq > 2) then
		module:log("warn", "ignoring invalid iq result from managing entity %s", stanza.attr.from)
		stanza_cache[stanza.attr.from][stanza.attr.id] = nil
		return true
	end

	iq.attr.xmlns = nil

	local original = stanza_cache[stanza.attr.from][stanza.attr.id]
	stanza_cache[stanza.attr.from][stanza.attr.id] = nil
	-- we get namespace from original and not iq
	-- because the namespace can be lacking in case of error
	local namespace = original.tags[1].attr.xmlns

	-- small hack for disco remaining feat
	if namespace == _DISCO_ITEMS_NS then
		namespace = _DISCO_ITEMS_REMAINING
	elseif namespace == _DISCO_INFO_NS then
		namespace = _DISCO_REMAINING
	end

	local ns_data = ns_delegations[namespace]

	if stanza.attr.from ~= ns_data.connected or (iq.attr.type ~= "result" and iq.attr.type ~= "error") or
		iq.attr.id ~= original.attr.id or iq.attr.to ~= original.attr.from then
		module:log("warn", "ignoring forbidden iq result from managing entity %s, please check that the component is no trying to do something bad (stanza: %s)", stanza.attr.from, tostring(stanza))
		module:send(st.error_reply(original, 'cancel', 'service-unavailable'))
		return true
	end

	-- at this point eveything is checked,
	-- and we (hopefully) can send the the result safely
	module:send(iq)
	return true
end

function managing_ent_error(event)
	local stanza = event.stanza
	if stanza.attr.to ~= module.host then
		module:log("warn", 'Stanza result has "to" attribute not addressed to current host, id conflict ?')
		return
	end
	module:unhook("iq-result/host/"..stanza.attr.id, managing_ent_result)
	module:unhook("iq-error/host/"..stanza.attr.id, managing_ent_error)
	local original = stanza_cache[stanza.attr.from][stanza.attr.id]
	stanza_cache[stanza.attr.from][stanza.attr.id] = nil
	module:log("warn", "Got an error after forwarding stanza to "..stanza.attr.from)
	module:send(st.error_reply(original, 'cancel', 'service-unavailable'))
	return true
end

local function forward_iq(stanza, ns_data)
	local to_jid = ns_data.connected
	stanza.attr.xmlns = 'jabber:client'
	local iq_id = new_id();
	local iq_stanza  = st.iq({ from=module.host, to=to_jid, type="set", id = iq_id })
		:tag("delegation", { xmlns=_DELEGATION_NS })
		:tag("forwarded", { xmlns=_FORWARDED_NS })
		:add_child(stanza)
	-- we save the original stanza to check the managing entity result
	if not stanza_cache[to_jid] then stanza_cache[to_jid] = {} end
	stanza_cache[to_jid][iq_id] = stanza
	module:hook("iq-result/host/"..iq_id, managing_ent_result)
	module:hook("iq-error/host/"..iq_id, managing_ent_error)
	module:log("debug", "stanza forwarded")
	module:send(iq_stanza)
end

local function iq_hook(event)
	-- general hook for all the iq which forward delegated ones
	-- and continue normal behaviour else. If a namespace is
	-- delegated but managing entity is offline, a service-unavailable
	-- error will be sent, as requested by the XEP
	local session, stanza = event.origin, event.stanza
	if #stanza == 1 and stanza.attr.type == 'get' or stanza.attr.type == 'set' then
		local namespace = stanza.tags[1].attr.xmlns
		local ns_data = ns_delegations[namespace]

		if ns_data then
			if stanza.attr.from == ns_data.connected then
				-- we don't forward stanzas from managing entity itself
				return
			end
			if ns_data.filtering then
				local first_child = stanza.tags[1]
				for _, attribute in pairs(ns_data.filtering) do
					-- if any filtered attribute if not present,
					-- we must continue the normal bahaviour
					if not first_child.attr[attribute] then
						-- Filtered attribute is not present, we do normal workflow
						return
					end
				end
			end
			if not ns_data.connected then
				module:log("warn", "No connected entity to manage "..namespace)
				session.send(st.error_reply(stanza, 'cancel', 'service-unavailable'))
			else
				forward_iq(stanza, ns_data)
			end
			return true
		else
			-- we have no delegation, we continue normal behaviour
			return
		end
	end
end

module:hook("iq/self", iq_hook, 2^32)
module:hook("iq/bare", iq_hook, 2^32)
module:hook("iq/host", iq_hook, 2^32)


--> discovery nesting <--

-- disabling internal features/identities

local function find_form_type(stanza)
	local form_type = nil
	for field in stanza:childtags('field', 'jabber:x:data') do
		if field.attr.var=='FORM_TYPE' and field.attr.type=='hidden' then
			local value = field:get_child('value')
			if not value then
				module:log("warn", "No value found in FORM_TYPE field: "..tostring(stanza))
			else
				form_type=value.get_text()
			end
		end
	end
	return form_type
end

-- modules whose features/identities are managed by delegation
local disabled_modules = set.new()
local disabled_identities = set.new()

local function identity_added(event)
	local source = event.source
	if disabled_modules:contains(source) then
		local item = event.item
		local category, type_, name = item.category, item.type, item.name
		module:log("debug", "Removing (%s/%s%s) identity because of delegation", category, type_, name and "/"..name or "")
		disabled_identities:add(item)
		source:remove_item("identity", item)
	end
end

local function feature_added(event)
	local source, item = event.source, event.item
	for namespace, _ in pairs(ns_delegations) do
		if source ~= nil and source ~= module and string.sub(item, 1, #namespace) == namespace then
			module:log("debug", "Removing %s feature which is delegated", item)
			source:remove_item("feature", item)
			disabled_modules:add(source)
			if source.items and source.items.identity then
				-- we remove all identities added by the source module
				-- that can cause issues if the module manages several features/identities
				-- but this case is probably rare (or doesn't happen at all)
				-- FIXME: any better way ?
				for _, identity in pairs(source.items.identity) do
					identity_added({source=source, item=identity})
				end
			end
		end
	end
end

local function extension_added(event)
	local source, stanza = event.source, event.item
	local form_type = find_form_type(stanza)
	if not form_type then return end

	for namespace, _ in pairs(ns_delegations) do
		if source ~= nil and source ~= module and string.sub(form_type, 1, #namespace) == namespace then
			module:log("debug", "Removing extension which is delegated: %s", tostring(stanza))
			source:remove_item("extension", stanza)
		end
	end
end

-- for disco nesting (see § 7.2) we need to remove internal features
-- we use handle_items as it allows to remove already added features
-- and catch the ones which can come later
module:handle_items("feature", feature_added, function(_) end)
module:handle_items("identity", identity_added, function(_) end, false)
module:handle_items("extension", extension_added, function(_) end)


-- managing entity features/identities collection

local disco_error
local bare_features = set.new()
local bare_identities = {}
local bare_extensions = {}

local function disco_result(event)
	-- parse result from disco nesting request
	-- and fill module features/identities and bare_features/bare_identities accordingly
	local session, stanza = event.origin, event.stanza
	if stanza.attr.to ~= module.host then
		module:log("warn", 'Stanza result has "to" attribute not addressed to current host, id conflict ?')
		return
	end
	module:unhook("iq-result/host/"..stanza.attr.id, disco_result)
	module:unhook("iq-error/host/"..stanza.attr.id, disco_error)
	local query = stanza:get_child("query", _DISCO_INFO_NS)
	if not query or not query.attr.node then
		session.send(st.error_reply(stanza, 'modify', 'not-acceptable'))
		return true
	end

	local node = query.attr.node
	local main

	if string.sub(node, 1, #_MAIN_PREFIX) == _MAIN_PREFIX then
		main=true
	elseif string.sub(node, 1, #_BARE_PREFIX) == _BARE_PREFIX then
		main=false
	else
		module:log("warn", "Unexpected node: "..node)
		session.send(st.error_reply(stanza, 'modify', 'not-acceptable'))
		return true
	end

	for feature in query:childtags("feature") do
		local namespace = feature.attr.var
		if main then
			module:add_feature(namespace)
		else
			bare_features:add(namespace)
		end
	end
	for identity in query:childtags("identity") do
		local category, type_, name = identity.attr.category, identity.attr.type, identity.attr.name
		if main then
			module:add_identity(category, type_, name)
		else
			table.insert(bare_identities, {category=category, type=type_, name=name})
		end
	end
	for extension in query:childtags("x", _DATA_NS) do
		if main then
			module:add_extension(extension)
		else
			table.insert(bare_extensions, extension)
		end
	end
end

function disco_error(event)
	local stanza = event.stanza
	if stanza.attr.to ~= module.host then
		module:log("warn", 'Stanza result has "to" attribute not addressed to current host, id conflict ?')
		return
	end
	module:unhook("iq-result/host/"..stanza.attr.id, disco_result)
	module:unhook("iq-error/host/"..stanza.attr.id, disco_error)
	module:log("warn", "Got an error while requesting disco for nesting to "..stanza.attr.from)
	module:log("warn", "Ignoring disco nesting")
end

function disco_nest(namespace, entity_jid)
	-- manage discovery nesting (see § 7.2)

	-- first we reset the current values
	if module.items then
		module.items['feature'] = nil
		module.items['identity'] = nil
		module.items['extension'] = nil
		bare_features = set.new()
		bare_identities = {}
		bare_extensions = {}
	end

	for _, prefix in ipairs(_PREFIXES) do
		local node = prefix..namespace

		local iq_id = new_id();
		local iq = st.iq({from=module.host, to=entity_jid, type='get', id = iq_id })
			:tag('query', {xmlns=_DISCO_INFO_NS, node=node})

		module:hook("iq-result/host/"..iq_id, disco_result)
		module:hook("iq-error/host/"..iq_id, disco_error)
		module:send(iq)
	end
end

-- disco to bare jids special cases

-- disco#info

local function disco_hook(event)
	-- this event is called when a disco info request is done on a bare jid
	-- we get the final reply and filter delegated features/identities/extensions
	local reply = event.reply
	reply.tags[1]:maptags(function(child)
		if child.name == 'feature' then
			local feature_ns = child.attr.var
			for namespace, _ in pairs(ns_delegations) do
				if string.sub(feature_ns, 1, #namespace) == namespace then
					module:log("debug", "Removing feature namespace %s which is delegated", feature_ns)
					return nil
				end
			end
		elseif child.name == 'identity' then
			for item in disabled_identities:items() do
				if item.category == child.attr.category
					and item.type == child.attr.type
					-- we don't check name, because mod_pep use a name for main disco, but not in account-disco-info hook
					-- and item.name == child.attr.name
				then
					module:log("debug", "Removing (%s/%s%s) identity because of delegation", item.category, item.type, item.name and "/"..item.name or "")
					return nil
				end
			end
		elseif child.name == 'x' and child.attr.xmlns == _DATA_NS then
			local form_type = find_form_type(child)
			if form_type then
				for namespace, _ in pairs(ns_delegations) do
					if string.sub(form_type, 1, #namespace) == namespace then
						module:log("debug", "Removing extension which is delegated: %s", tostring(child))
						return nil
					end
				end
			end

		end
		return child
	end)
	for feature in bare_features:items() do
		reply:tag('feature', {var=feature}):up()
	end
	for _, item in ipairs(bare_identities) do
		reply:tag('identity', {category=item.category, type=item.type, name=item.name}):up()
	end
	for _, stanza in ipairs(bare_extensions) do
		reply:add_child(stanza)
	end

end
module:hook("account-disco-info", disco_hook, -2^32)

local function disco_node_hook(event)
	-- we reach this hook if a disco node on account has not been found
	-- we then forward the request to managing entity
	if not event.exists then
		-- this node is not handled by the server
		local ns_data = ns_delegations[_DISCO_REMAINING]
		if ns_data ~= nil then
			-- remaining delegation is requested, we forward
			forward_iq(event.stanza, ns_data)
			-- and stop normal event handling
			return true
		end
	end
end
module:hook("account-disco-info-node", disco_node_hook, -2^32)

-- disco#items

local function disco_items_node_hook(event)
	-- check if node is not handled by server
	-- and forward the disco request to suitable entity
	if not event.exists then
		-- this node is not handled by the server
		local ns_data = ns_delegations[_DISCO_ITEMS_REMAINING]
		if ns_data ~= nil then
			-- remaining delegation is requested, we forward
			forward_iq(event.stanza, ns_data)
			-- and stop normal event handling
			return true
		end
	end
end
module:hook("account-disco-items-node", disco_items_node_hook, -2^32)

local function disco_items_hook(event)
	-- FIXME: we forward all bare-jid disco-items requests (without node) which will replace any Prosody reply
	--		for now it's OK because Prosody is not returning anything on request on bare jid
	--		but to be properly done, any Prosody reply should be kept and managing entities items should be added (merged) to it.
	--		account-disco-items can't be cancelled (return value of hooks are not checked in mod_disco), so coroutine needs
	--		to be used with util.async (to get the IQ result, merge items then return from the event)
	local origin, stanza = event.origin, event.stanza;
	local node = stanza.tags[1].attr.node;
	local username = jid_split(stanza.attr.to) or origin.username;
	if not stanza.attr.to or is_contact_subscribed(username, module.host, jid_bare(stanza.attr.from)) then
		if node == nil or node == "" then
			local ns_data = ns_delegations[_DISCO_ITEMS_REMAINING]
			if ns_data ~= nil then
				forward_iq(event.stanza, ns_data)
				return true
			end
		end
	end
end
module:hook("iq-get/bare/http://jabber.org/protocol/disco#items:query", disco_items_hook, 100)

local function disco_items_raw_hook(event)
	-- this method is called when account-disco-items-* event are not called
	-- notably when a disco-item is done by an unsubscibed entity
	-- (i.e. an entity doing a disco#item on an entity without having
	-- presence subscription)
	-- we forward the request to managing entity
	-- it's the responsability of the managing entity to filter the items
	local ns_data = ns_delegations[_DISCO_ITEMS_REMAINING]
	if ns_data ~= nil then
		forward_iq(event.stanza, ns_data)
		return true
	end
end
module:hook("iq-get/bare/http://jabber.org/protocol/disco#items:query", disco_items_raw_hook, -2^32)