plugins/mod_privacy.lua

-- Prosody IM
-- Copyright (C) 2009-2010 Matthew Wild
-- Copyright (C) 2009-2010 Waqas Hussain
-- Copyright (C) 2009 Thilo Cestonaro
-- 
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

module:add_feature("jabber:iq:privacy");

local prosody = prosody;
local st = require "util.stanza";
local datamanager = require "util.datamanager";
local bare_sessions, full_sessions = bare_sessions, full_sessions;
local util_Jid = require "util.jid";
local jid_bare = util_Jid.bare;
local jid_split, jid_join = util_Jid.split, util_Jid.join;
local load_roster = require "core.rostermanager".load_roster;
local to_number = tonumber;

function isListUsed(origin, name, privacy_lists)
	local user = bare_sessions[origin.username.."@"..origin.host];
	if user then
		for resource, session in pairs(user.sessions) do
			if resource ~= origin.resource then
				if session.activePrivacyList == name then
					return true;
				elseif session.activePrivacyList == nil and privacy_lists.default == name then
					return true;
				end
			end
		end
	end
end

function isAnotherSessionUsingDefaultList(origin)
	local user = bare_sessions[origin.username.."@"..origin.host];
	if user then
		for resource, session in pairs(user.sessions) do
			if resource ~= origin.resource and session.activePrivacyList == nil then
				return true;
			end
		end
	end
end

function sendUnavailable(origin, to, from)
--[[ example unavailable presence stanza
<presence from="node@host/resource" type="unavailable" to="node@host" >
	<status>Logged out</status>
</presence>
]]--
	local presence = st.presence({from=from, type="unavailable"});
	presence:tag("status"):text("Logged out");

	local node, host = jid_bare(to);
	local bare = node .. "@" .. host;
	
	local user = bare_sessions[bare];
	if user then
		for resource, session in pairs(user.sessions) do
			presence.attr.to = session.full_jid;
			module:log("debug", "send unavailable to: %s; from: %s", tostring(presence.attr.to), tostring(presence.attr.from));
			origin.send(presence);
		end
	end
end

function declineList(privacy_lists, origin, stanza, which)
	if which == "default" then
		if isAnotherSessionUsingDefaultList(origin) then
			return { "cancel", "conflict", "Another session is online and using the default list."};
		end
		privacy_lists.default = nil;
		origin.send(st.reply(stanza));
	elseif which == "active" then
		origin.activePrivacyList = nil;
		origin.send(st.reply(stanza));
	else
		return {"modify", "bad-request", "Neither default nor active list specifed to decline."};
	end
	return true;
end

function activateList(privacy_lists, origin, stanza, which, name)
	local list = privacy_lists.lists[name];

	if which == "default" and list then
		if isAnotherSessionUsingDefaultList(origin) then
			return {"cancel", "conflict", "Another session is online and using the default list."};
		end
		privacy_lists.default = name;
		origin.send(st.reply(stanza));
	elseif which == "active" and list then
		origin.activePrivacyList = name;
		origin.send(st.reply(stanza));
	elseif not list then
		return {"cancel", "item-not-found", "No such list: "..name};
	else
		return {"modify", "bad-request", "No list chosen to be active or default."};
	end
	return true;
end

function deleteList(privacy_lists, origin, stanza, name)
	local list = privacy_lists.lists[name];

	if list then
		if isListUsed(origin, name, privacy_lists) then
			return {"cancel", "conflict", "Another session is online and using the list which should be deleted."};
		end
		if privacy_lists.default == name then
			privacy_lists.default = nil;
		end
		if origin.activePrivacyList == name then
			origin.activePrivacyList = nil;
		end
		privacy_lists.lists[name] = nil;
		origin.send(st.reply(stanza));
		return true;
	end
	return {"modify", "bad-request", "Not existing list specifed to be deleted."};
end

function createOrReplaceList (privacy_lists, origin, stanza, name, entries, roster)
	local bare_jid = origin.username.."@"..origin.host;
	
	if privacy_lists.lists == nil then
		privacy_lists.lists = {};
	end

	local list = {};
	privacy_lists.lists[name] = list;

	local orderCheck = {};
	list.name = name;
	list.items = {};

	for _,item in ipairs(entries) do
		if to_number(item.attr.order) == nil or to_number(item.attr.order) < 0 or orderCheck[item.attr.order] ~= nil then
			return {"modify", "bad-request", "Order attribute not valid."};
		end
		
		if item.attr.type ~= nil and item.attr.type ~= "jid" and item.attr.type ~= "subscription" and item.attr.type ~= "group" then
			return {"modify", "bad-request", "Type attribute not valid."};
		end
		
		local tmp = {};
		orderCheck[item.attr.order] = true;
		
		tmp["type"] = item.attr.type;
		tmp["value"] = item.attr.value;
		tmp["action"] = item.attr.action;
		tmp["order"] = to_number(item.attr.order);
		tmp["presence-in"] = false;
		tmp["presence-out"] = false;
		tmp["message"] = false;
		tmp["iq"] = false;
		
		if #item.tags > 0 then
			for _,tag in ipairs(item.tags) do
				tmp[tag.name] = true;
			end
		end
		
		if tmp.type == "subscription" then
			if	tmp.value ~= "both" and
				tmp.value ~= "to" and
				tmp.value ~= "from" and
				tmp.value ~= "none" then
				return {"cancel", "bad-request", "Subscription value must be both, to, from or none."};
			end
		end
		
		if tmp.action ~= "deny" and tmp.action ~= "allow" then
			return {"cancel", "bad-request", "Action must be either deny or allow."};
		end
		list.items[#list.items + 1] = tmp;
	end
	
	table.sort(list, function(a, b) return a.order < b.order; end);

	origin.send(st.reply(stanza));
	if bare_sessions[bare_jid] ~= nil then
		local iq = st.iq ( { type = "set", id="push1" } );
		iq:tag ("query", { xmlns = "jabber:iq:privacy" } );
		iq:tag ("list", { name = list.name } ):up();
		iq:up();
		for resource, session in pairs(bare_sessions[bare_jid].sessions) do
			iq.attr.to = bare_jid.."/"..resource
			session.send(iq);
		end
	else
		return {"cancel", "bad-request", "internal error."};
	end
	return true;
end

function getList(privacy_lists, origin, stanza, name)
	local reply = st.reply(stanza);
	reply:tag("query", {xmlns="jabber:iq:privacy"});

	if name == nil then
		if privacy_lists.lists then
			if origin.activePrivacyList then
				reply:tag("active", {name=origin.activePrivacyList}):up();
			end
			if privacy_lists.default then
				reply:tag("default", {name=privacy_lists.default}):up();
			end
			for name,list in pairs(privacy_lists.lists) do
				reply:tag("list", {name=name}):up();
			end
		end
	else
		local list = privacy_lists.lists[name];
		if list then
			reply = reply:tag("list", {name=list.name});
			for _,item in ipairs(list.items) do
				reply:tag("item", {type=item.type, value=item.value, action=item.action, order=item.order});
				if item["message"] then reply:tag("message"):up(); end
				if item["iq"] then reply:tag("iq"):up(); end
				if item["presence-in"] then reply:tag("presence-in"):up(); end
				if item["presence-out"] then reply:tag("presence-out"):up(); end
				reply:up();
			end
		else
			return {"cancel", "item-not-found", "Unknown list specified."};
		end
	end
	
	origin.send(reply);
	return true;
end

module:hook("iq/bare/jabber:iq:privacy:query", function(data)
	local origin, stanza = data.origin, data.stanza;
	
	if stanza.attr.to == nil then -- only service requests to own bare JID
		local query = stanza.tags[1]; -- the query element
		local valid = false;
		local privacy_lists = datamanager.load(origin.username, origin.host, "privacy") or { lists = {} };

		if privacy_lists.lists[1] then -- Code to migrate from old privacy lists format, remove in 0.8
			module:log("info", "Upgrading format of stored privacy lists for %s@%s", origin.username, origin.host);
			local lists = privacy_lists.lists;
			for idx, list in ipairs(lists) do
				lists[list.name] = list;
				lists[idx] = nil;
			end
		end

		if stanza.attr.type == "set" then
			if #query.tags == 1 then --  the <query/> element MUST NOT include more than one child element
				for _,tag in ipairs(query.tags) do
					if tag.name == "active" or tag.name == "default" then
						if tag.attr.name == nil then -- Client declines the use of active / default list
							valid = declineList(privacy_lists, origin, stanza, tag.name);
						else -- Client requests change of active / default list
							valid = activateList(privacy_lists, origin, stanza, tag.name, tag.attr.name);
						end
					elseif tag.name == "list" and tag.attr.name then -- Client adds / edits a privacy list
						if #tag.tags == 0 then -- Client removes a privacy list
							valid = deleteList(privacy_lists, origin, stanza, tag.attr.name);
						else -- Client edits a privacy list
							valid = createOrReplaceList(privacy_lists, origin, stanza, tag.attr.name, tag.tags);
						end
					end
				end
			end
		elseif stanza.attr.type == "get" then
			local name = nil;
			local listsToRetrieve = 0;
			if #query.tags >= 1 then
				for _,tag in ipairs(query.tags) do
					if tag.name == "list" then -- Client requests a privacy list from server
						name = tag.attr.name;
						listsToRetrieve = listsToRetrieve + 1;
					end
				end
			end
			if listsToRetrieve == 0 or listsToRetrieve == 1 then
				valid = getList(privacy_lists, origin, stanza, name);
			end
		end

		if valid ~= true then
			valid = valid or { "cancel", "bad-request", "Couldn't understand request" };
			if valid[1] == nil then
				valid[1] = "cancel";
			end
			if valid[2] == nil then
				valid[2] = "bad-request";
			end
			origin.send(st.error_reply(stanza, valid[1], valid[2], valid[3]));
		else
			datamanager.store(origin.username, origin.host, "privacy", privacy_lists);
		end
		return true;
	end
end);

function checkIfNeedToBeBlocked(e, session)
	local origin, stanza = e.origin, e.stanza;
	local privacy_lists = datamanager.load(session.username, session.host, "privacy") or {};
	local bare_jid = session.username.."@"..session.host;
	local to = stanza.attr.to or bare_jid;
	local from = stanza.attr.from;
	
	local is_to_user = bare_jid == jid_bare(to);
	local is_from_user = bare_jid == jid_bare(from);
	
	--module:log("debug", "stanza: %s, to: %s, from: %s", tostring(stanza.name), tostring(to), tostring(from));
	
	if privacy_lists.lists == nil or
		not (session.activePrivacyList or privacy_lists.default)
	then
		return; -- Nothing to block, default is Allow all
	end
	if is_from_user and is_to_user then
		--module:log("debug", "Not blocking communications between user's resources");
		return; -- from one of a user's resource to another => HANDS OFF!
	end
	
	local item;
	local listname = session.activePrivacyList;
	if listname == nil then
		listname = privacy_lists.default; -- no active list selected, use default list
	end
	local list = privacy_lists.lists[listname];
	if not list then -- should never happen
		module:log("warn", "given privacy list not found. name: %s for user %s", listname, bare_jid);
		return;
	end
	for _,item in ipairs(list.items) do
		local apply = false;
		local block = false;
		if (
			(stanza.name == "message" and item.message) or
			(stanza.name == "iq" and item.iq) or
			(stanza.name == "presence" and is_to_user and item["presence-in"]) or
			(stanza.name == "presence" and is_from_user and item["presence-out"]) or
			(item.message == false and item.iq == false and item["presence-in"] == false and item["presence-out"] == false)
		) then
			apply = true;
		end
		if apply then
			local evilJid = {};
			apply = false;
			if is_to_user then
				--module:log("debug", "evil jid is (from): %s", from);
				evilJid.node, evilJid.host, evilJid.resource = jid_split(from);
			else
				--module:log("debug", "evil jid is (to): %s", to);
				evilJid.node, evilJid.host, evilJid.resource = jid_split(to);
			end
			if	item.type == "jid" and
				(evilJid.node and evilJid.host and evilJid.resource and item.value == evilJid.node.."@"..evilJid.host.."/"..evilJid.resource) or
				(evilJid.node and evilJid.host and item.value == evilJid.node.."@"..evilJid.host) or
				(evilJid.host and evilJid.resource and item.value == evilJid.host.."/"..evilJid.resource) or
				(evilJid.host and item.value == evilJid.host) then
				apply = true;
				block = (item.action == "deny");
			elseif item.type == "group" then
				local roster = load_roster(session.username, session.host);
				local roster_entry = roster[jid_join(evilJid.node, evilJid.host)];
				if roster_entry then
					local groups = roster_entry.groups;
					for group in pairs(groups) do
						if group == item.value then
							apply = true;
							block = (item.action == "deny");
							break;
						end
					end
				end
			elseif item.type == "subscription" then -- we need a valid bare evil jid
				local roster = load_roster(session.username, session.host);
				local roster_entry = roster[jid_join(evilJid.node, evilJid.host)];
				if (not(roster_entry) and item.value == "none")
				   or (roster_entry and roster_entry.subscription == item.value) then
					apply = true;
					block = (item.action == "deny");
				end
			elseif item.type == nil then
				apply = true;
				block = (item.action == "deny");
			end
		end
		if apply then
			if block then
				module:log("debug", "stanza blocked: %s, to: %s, from: %s", tostring(stanza.name), tostring(to), tostring(from));
				if stanza.name == "message" then
					origin.send(st.error_reply(stanza, "cancel", "service-unavailable"));
				elseif stanza.name == "iq" and (stanza.attr.type == "get" or stanza.attr.type == "set") then
					origin.send(st.error_reply(stanza, "cancel", "service-unavailable"));
				end
				return true; -- stanza blocked !
			else
				--module:log("debug", "stanza explicitly allowed!")
				return;
			end
		end
	end
end

function preCheckIncoming(e)
	local session;
	if e.stanza.attr.to ~= nil then
		local node, host, resource = jid_split(e.stanza.attr.to);
		if node == nil or host == nil then
			return;
		end
		if resource == nil then
			local prio = 0;
			local session_;
			if bare_sessions[node.."@"..host] ~= nil then
				for resource, session_ in pairs(bare_sessions[node.."@"..host].sessions) do
					if session_.priority ~= nil and session_.priority > prio then
						session = session_;
						prio = session_.priority;
					end
				end
			end
		else
			session = full_sessions[node.."@"..host.."/"..resource];
		end
		if session ~= nil then
			return checkIfNeedToBeBlocked(e, session);
		else
			--module:log("debug", "preCheckIncoming: Couldn't get session for jid: %s@%s/%s", tostring(node), tostring(host), tostring(resource));
		end
	end
end

function preCheckOutgoing(e)
	local session = e.origin;
	if e.stanza.attr.from == nil then
		e.stanza.attr.from = session.username .. "@" .. session.host;
		if session.resource ~= nil then
		 	e.stanza.attr.from = e.stanza.attr.from .. "/" .. session.resource;
		end
	end
	if session.username then -- FIXME do properly
		return checkIfNeedToBeBlocked(e, session);
	end
end

module:hook("pre-message/full", preCheckOutgoing, 500);
module:hook("pre-message/bare", preCheckOutgoing, 500);
module:hook("pre-message/host", preCheckOutgoing, 500);
module:hook("pre-iq/full", preCheckOutgoing, 500);
module:hook("pre-iq/bare", preCheckOutgoing, 500);
module:hook("pre-iq/host", preCheckOutgoing, 500);
module:hook("pre-presence/full", preCheckOutgoing, 500);
module:hook("pre-presence/bare", preCheckOutgoing, 500);
module:hook("pre-presence/host", preCheckOutgoing, 500);

module:hook("message/full", preCheckIncoming, 500);
module:hook("message/bare", preCheckIncoming, 500);
module:hook("message/host", preCheckIncoming, 500);
module:hook("iq/full", preCheckIncoming, 500);
module:hook("iq/bare", preCheckIncoming, 500);
module:hook("iq/host", preCheckIncoming, 500);
module:hook("presence/full", preCheckIncoming, 500);
module:hook("presence/bare", preCheckIncoming, 500);
module:hook("presence/host", preCheckIncoming, 500);