--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_delegation/mod_delegation.lua	Thu May 07 23:39:54 2015 +0200
@@ -0,0 +1,519 @@
+-- XEP-0355 (Namespace Delegation)
+-- Copyright (C) 2015 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 delegation_session = module:shared("/*/delegation/session")
+
+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:1'
+local _FORWARDED_NS = 'urn:xmpp:forward:0'
+local _DISCO_NS = 'http://jabber.org/protocol/disco#info'
+local _DATA_NS = 'jabber:x:data'
+
+local _MAIN_SEP = '::'
+local _BARE_SEP = ':bare:'
+local _MAIN_PREFIX = _DELEGATION_NS.._MAIN_SEP
+local _BARE_PREFIX = _DELEGATION_NS.._BARE_SEP
+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
+				message:up()
+			end
+		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_nest(namespace, entity_jid)
+			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
+
+connected_cb:add(on_component_connected)
+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
+	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_stanza  = st.iq({ from=module.host, to=to_jid, type="set" })
+		:tag("delegation", { xmlns=_DELEGATION_NS })
+		:tag("forwarded", { xmlns=_FORWARDED_NS })
+		:add_child(stanza)
+	local iq_id = iq_stanza.attr.id
+	-- 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 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 ~= 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 ~= 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 allow 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_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 = st.iq({from=module.host, to=entity_jid, type='get'})
+			:tag('query', {xmlns=_DISCO_NS, node=node})
+
+		local iq_id = iq.attr.id
+
+		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 case
+
+module:hook("account-disco-info", function(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, -2^32);