--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_web_push/mod_web_push.lua	Sat Jun 08 23:06:44 2019 +0200
@@ -0,0 +1,404 @@
+-- XEP-XXXX: Web Push (aka: My mobile OS vendor won't let me have persistent TCP connections, take two)
+-- Copyright (C) 2019 Maxime “pep” Buquet
+--
+-- Heavily based on mod_cloud_notify.
+-- Copyright (C) 2015-2016 Kim Alvefur
+-- Copyright (C) 2017-2018 Thilo Molitor
+
+
+local st = require"util.stanza";
+local dataform = require "util.dataforms";
+local http = require "net.http";
+
+local os_time = os.time;
+local next = next;
+local jid = require"util.jid";
+local filters = require"util.filters";
+
+local xmlns_webpush = "urn:xmpp:webpush:0";
+
+local max_push_devices = module:get_option_number("push_max_devices", 5);
+local dummy_body = module:get_option_string("push_notification_important_body", "New Message!");
+
+local host_sessions = prosody.hosts[module.host].sessions;
+
+-- TODO: Generate it at setup time. Obviously not to be used other than for
+-- testing purposes, or at all.
+-- ECDH keypair
+local server_pubkey = "MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEhxZpb8yIVc/2hNesGLGAxEakyYy0MqEetjgL7BIOm8ybhVKxapKqNXjXJ+NOO5/b0Z0UuBg/HynGnf0xKKNhBQ==";
+local server_privkey = "MHcCAQEEIPhZac9pQ8aVTx9a5JyRcqfk3nuQQUFy3PaDcSWleojzoAoGCCqGSM49AwEHoUQDQgAEhxZpb8yIVc/2hNesGLGAxEakyYy0MqEetjgL7BIOm8ybhVKxapKqNXjXJ+NOO5/b0Z0UuBg/HynGnf0xKKNhBQ==";
+
+-- Advertize disco feature
+local function account_disco_info(event)
+	local form = dataform.new {
+		{ name = "FORM_TYPE", type = "hidden", value = "http://jabber.org/protocol/webpush#public-key" };
+		{ name = "webpush#public-key", value = server_pubkey };
+	};
+	(event.reply or event.stanza):tag("feature", {var=xmlns_webpush}):up()
+	:add_child(form:form({}, "result"));
+end
+module:hook("account-disco-info", account_disco_info);
+
+-- ordered table iterator, allow to iterate on the natural order of the keys of a table,
+-- see http://lua-users.org/wiki/SortedIteration
+local function __genOrderedIndex( t )
+	local orderedIndex = {}
+	for key in pairs(t) do
+		table.insert( orderedIndex, key )
+	end
+	-- sort in reverse order (newest one first)
+	table.sort( orderedIndex, function(a, b)
+		if a == nil or t[a] == nil or b == nil or t[b] == nil then return false end
+		-- only one timestamp given, this is the newer one
+		if t[a].timestamp ~= nil and t[b].timestamp == nil then return true end
+		if t[a].timestamp == nil and t[b].timestamp ~= nil then return false end
+		-- both timestamps given, sort normally
+		if t[a].timestamp ~= nil and t[b].timestamp ~= nil then return t[a].timestamp > t[b].timestamp end
+		return false -- normally not reached
+	end)
+	return orderedIndex
+end
+local function orderedNext(t, state)
+	-- Equivalent of the next function, but returns the keys in timestamp
+	-- order. We use a temporary ordered key table that is stored in the
+	-- table being iterated.
+
+	local key = nil
+	--print("orderedNext: state = "..tostring(state) )
+	if state == nil then
+		-- the first time, generate the index
+		t.__orderedIndex = __genOrderedIndex( t )
+		key = t.__orderedIndex[1]
+	else
+		-- fetch the next value
+		for i = 1, #t.__orderedIndex do
+			if t.__orderedIndex[i] == state then
+				key = t.__orderedIndex[i+1]
+			end
+		end
+	end
+
+	if key then
+		return key, t[key]
+	end
+
+	-- no more value to return, cleanup
+	t.__orderedIndex = nil
+	return
+end
+local function orderedPairs(t)
+	-- Equivalent of the pairs() function on tables. Allows to iterate
+	-- in order
+	return orderedNext, t, nil
+end
+
+-- small helper function to return new table with only "maximum" elements containing only the newest entries
+local function reduce_table(table, maximum)
+	local count = 0;
+	local result = {};
+	for key, value in orderedPairs(table) do
+		count = count + 1;
+		if count > maximum then break end
+		result[key] = value;
+	end
+	return result;
+end
+
+local push_store = (function()
+	local store = module:open_store();
+	local push_services = {};
+	local api = {};
+	function api:get(user)
+		if not push_services[user] then
+			local err;
+			push_services[user], err = store:get(user);
+			if not push_services[user] and err then
+				module:log("warn", "Error reading web push notification storage for user '%s': %s", user, tostring(err));
+				push_services[user] = {};
+				return push_services[user], false;
+			end
+		end
+		if not push_services[user] then push_services[user] = {} end
+		return push_services[user], true;
+	end
+	function api:set(user, data)
+		push_services[user] = reduce_table(data, max_push_devices);
+		local ok, err = store:set(user, push_services[user]);
+		if not ok then
+			module:log("error", "Error writing web push notification storage for user '%s': %s", user, tostring(err));
+			return false;
+		end
+		return true;
+	end
+	function api:set_identifier(user, push_identifier, data)
+		local services = self:get(user);
+		services[push_identifier] = data;
+		return self:set(user, services);
+	end
+	return api;
+end)();
+
+local function push_enable(event)
+	local origin, stanza = event.origin, event.stanza;
+	local enable = stanza.tags[1];
+	origin.log("debug", "Attempting to enable web push notifications");
+	-- MUST contain a 'href' attribute of the XMPP Push Service being enabled
+	local push_endpoint = nil;
+	local push_auth = nil;
+	local push_p256dh = nil;
+
+	local endpoint_tag = enable:get_child('endpoint');
+	if endpoint_tag ~= nil then
+		push_endpoint = endpoint_tag:get_text();
+	end
+	local auth_tag = enable:get_child('auth');
+	if auth_tag ~= nil then
+		push_auth = auth_tag:get_text();
+	end
+	local p256dh_tag = enable:get_child('p256dh');
+	if p256dh_tag ~= nil then
+		push_p256dh = p256dh_tag:get_text();
+	end
+	if not push_endpoint or not push_auth or not push_p256dh then
+		origin.log("debug", "Web Push notification enable request missing 'endpoint', 'auth', or 'p256dh' tags");
+		origin.send(st.error_reply(stanza, "modify", "bad-request", "Missing enable child tag"));
+		return true;
+	end
+	local push_identifier = "foo";
+	local push_service = push_endpoint;
+	local ok = push_store:set_identifier(origin.username, push_identifier, push_service);
+	if not ok then
+		origin.send(st.error_reply(stanza, "wait", "internal-server-error"));
+	else
+		origin.push_identifier = push_identifier;
+		origin.push_settings = push_service;
+		origin.log("info", "Web Push notifications enabled for %s (%s)", tostring(stanza.attr.from), tostring(origin.push_identifier));
+		origin.send(st.reply(stanza));
+	end
+	return true;
+end
+module:hook("iq-set/self/"..xmlns_webpush..":enable", push_enable);
+
+-- module:hook("iq-set/self/"..xmlns_webpush..":disable", push_disable);
+
+-- small helper function to extract relevant push settings
+local function get_push_settings(stanza, session)
+	local to = stanza.attr.to;
+	local node = to and jid.split(to) or session.username;
+	local user_push_services = push_store:get(node);
+	return node, user_push_services;
+end
+
+local function log_http_req(response_body, response_code, response)
+	module:log("debug", "FOO: response_body: %s; response_code: %s; response: %s", response_body, tostring(response_code), tostring(response));
+end
+
+local function handle_notify_request(stanza, node, user_push_services, log_push_decline)
+	local pushes = 0;
+	if not user_push_services or next(user_push_services) == nil then return pushes end
+
+	for push_identifier, push_info in pairs(user_push_services) do
+		local send_push = true;		-- only send push to this node when not already done for this stanza or if no stanza is given at all
+		if stanza then
+			if not stanza._push_notify then stanza._push_notify = {}; end
+			if stanza._push_notify[push_identifier] then
+				if log_push_decline then
+					module:log("debug", "Already sent push notification for %s@%s to %s", node, module.host, tostring(push_info));
+				end
+				send_push = false;
+			end
+			stanza._push_notify[push_identifier] = true;
+		end
+
+		if send_push then
+			local headers = { TTL = "60" };
+			http.request(push_info, { method = "POST", headers = headers }, log_http_req);
+			pushes = pushes + 1;
+		end
+	end
+	return pushes;
+end
+
+-- publish on offline message
+module:hook("message/offline/handle", function(event)
+	local node, user_push_services = get_push_settings(event.stanza, event.origin);
+	module:log("debug", "Invoking web push handle_notify_request() for offline stanza");
+	handle_notify_request(event.stanza, node, user_push_services, true);
+end, 1);
+
+-- is this push a high priority one (this is needed for ios apps not using voip pushes)
+local function is_important(stanza)
+	local st_name = stanza and stanza.name or nil;
+	if not st_name then return false; end	-- nonzas are never important here
+	if st_name == "presence" then
+		return false;						-- same for presences
+	elseif st_name == "message" then
+		-- unpack carbon copies
+		local stanza_direction = "in";
+		local carbon;
+		local st_type;
+		-- support carbon copied message stanzas having an arbitrary message-namespace or no message-namespace at all
+		if not carbon then carbon = find(stanza, "{urn:xmpp:carbons:2}/forwarded/message"); end
+		if not carbon then carbon = find(stanza, "{urn:xmpp:carbons:1}/forwarded/message"); end
+		stanza_direction = carbon and stanza:child_with_name("sent") and "out" or "in";
+		if carbon then stanza = carbon; end
+		st_type = stanza.attr.type;
+
+		-- headline message are always not important
+		if st_type == "headline" then return false; end
+
+		-- carbon copied outgoing messages are not important
+		if carbon and stanza_direction == "out" then return false; end
+
+		-- We can't check for body contents in encrypted messages, so let's treat them as important
+		-- Some clients don't even set a body or an empty body for encrypted messages
+
+		-- check omemo https://xmpp.org/extensions/inbox/omemo.html
+		if stanza:get_child("encrypted", "eu.siacs.conversations.axolotl") or stanza:get_child("encrypted", "urn:xmpp:omemo:0") then return true; end
+
+		-- check xep27 pgp https://xmpp.org/extensions/xep-0027.html
+		if stanza:get_child("x", "jabber:x:encrypted") then return true; end
+
+		-- check xep373 pgp (OX) https://xmpp.org/extensions/xep-0373.html
+		if stanza:get_child("openpgp", "urn:xmpp:openpgp:0") then return true; end
+
+		local body = stanza:get_child_text("body");
+		if st_type == "groupchat" and stanza:get_child_text("subject") then return false; end -- groupchat subjects are not important here
+		return body ~= nil and body ~= ""; -- empty bodies are not important
+	end
+	return false; -- this stanza wasn't one of the above cases --> it is not important, too
+end
+
+-- publish on unacked smacks message
+local function process_smacks_stanza(stanza, session)
+	if session.push_identifier then
+		session.log("debug", "Invoking web push handle_notify_request() for smacks queued stanza");
+		local user_push_services = {[session.push_identifier] = session.push_settings};
+		local node = get_push_settings(stanza, session);
+		if handle_notify_request(stanza, node, user_push_services, true) ~= 0 then
+			if session.hibernating and not session.first_hibernated_push then
+				-- if important stanzas are treated differently (pushed with last-message-body field set to dummy string)
+				-- and the message was important (e.g. had a last-message-body field) OR if we treat all pushes equally,
+				-- then record the time of first push in the session for the smack module which will extend its hibernation
+				-- timeout based on the value of session.first_hibernated_push
+				if not dummy_body or (dummy_body and is_important(stanza)) then
+					session.first_hibernated_push = os_time();
+				end
+			end
+		end
+	end
+	return stanza;
+end
+
+local function process_smacks_queue(queue, session)
+	if not session.push_identifier then return; end
+	local user_push_services = {[session.push_identifier] = session.push_settings};
+	local notified = { unimportant = false; important = false }
+	for i=1, #queue do
+		local stanza = queue[i];
+		local node = get_push_settings(stanza, session);
+		local stanza_type = "unimportant"
+		if dummy_body and is_important(stanza) then stanza_type = "important"; end
+		if not notified[stanza_type] then -- only notify if we didn't try to push for this stanza type already
+			-- session.log("debug", "Invoking cloud handle_notify_request() for smacks queued stanza: %d", i);
+			if handle_notify_request(stanza, node, user_push_services, false) ~= 0 then
+				if session.hibernating and not session.first_hibernated_push then
+					-- if important stanzas are treated differently (pushed with last-message-body field set to dummy string)
+					-- and the message was important (e.g. had a last-message-body field) OR if we treat all pushes equally,
+					-- then record the time of first push in the session for the smack module which will extend its hibernation
+					-- timeout based on the value of session.first_hibernated_push
+					if not dummy_body or (dummy_body and is_important(stanza)) then
+						session.first_hibernated_push = os_time();
+					end
+				end
+				session.log("debug", "Web Push handle_notify_request() > 0, not notifying for other queued stanzas of type %s", stanza_type);
+				notified[stanza_type] = true
+			end
+		end
+	end
+end
+
+-- smacks hibernation is started
+local function hibernate_session(event)
+	local session = event.origin;
+	local queue = event.queue;
+	session.first_hibernated_push = nil;
+	-- process unacked stanzas
+	process_smacks_queue(queue, session);
+	-- process future unacked (hibernated) stanzas
+	filters.add_filter(session, "stanzas/out", process_smacks_stanza, -990);
+end
+
+-- smacks hibernation is ended
+local function restore_session(event)
+	local session = event.resumed;
+	if session then -- older smacks module versions send only the "intermediate" session in event.session and no session.resumed one
+		filters.remove_filter(session, "stanzas/out", process_smacks_stanza);
+		session.first_hibernated_push = nil;
+	end
+end
+
+-- smacks ack is delayed
+local function ack_delayed(event)
+	local session = event.origin;
+	local queue = event.queue;
+	-- process unacked stanzas (handle_notify_request() will only send push requests for new stanzas)
+	process_smacks_queue(queue, session);
+end
+
+-- archive message added
+local function archive_message_added(event)
+	-- event is: { origin = origin, stanza = stanza, for_user = store_user, id = id }
+	-- only notify for new mam messages when at least one device is online
+	if not event.for_user or not host_sessions[event.for_user] then return; end
+	local stanza = event.stanza;
+	local user_session = host_sessions[event.for_user].sessions;
+	local to = stanza.attr.to;
+	to = to and jid.split(to) or event.origin.username;
+
+	-- only notify if the stanza destination is the mam user we store it for
+	if event.for_user == to then
+		local user_push_services = push_store:get(to);
+		if next(user_push_services) == nil then return end
+
+		-- only notify nodes with no active sessions (smacks is counted as active and handled separate)
+		local notify_push_services = {};
+		for identifier, push_info in pairs(user_push_services) do
+			local identifier_found = nil;
+			for _, session in pairs(user_session) do
+				-- module:log("debug", "searching for '%s': identifier '%s' for session %s", tostring(identifier), tostring(session.push_identifier), tostring(session.full_jid));
+				if session.push_identifier == identifier then
+					identifier_found = session;
+					break;
+				end
+			end
+			if identifier_found then
+				identifier_found.log("debug", "Not web push notifying '%s' of new MAM stanza (session still alive)", identifier);
+			else
+				notify_push_services[identifier] = push_info;
+			end
+		end
+
+		handle_notify_request(event.stanza, to, notify_push_services, true);
+	end
+end
+
+module:hook("smacks-hibernation-start", hibernate_session);
+module:hook("smacks-hibernation-end", restore_session);
+module:hook("smacks-ack-delayed", ack_delayed);
+module:hook("archive-message-added", archive_message_added);
+
+function module.command(arg)
+  print("TODO: Generate server keypair")
+end
+
+module:log("info", "Module loaded");
+function module.unload()
+	if module.unhook then
+		module:unhook("account-disco-info", account_disco_info);
+		module:unhook("iq-set/self/"..xmlns_webpush..":enable", push_enable);
+		-- module:unhook("iq-set/self/"..xmlns_webpush..":disable", push_disable);
+	end
+
+	module:log("info", "Module unloaded");
+end