-- Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

-- 

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local lxp = require "lxp";

local st = require "util.stanza";

local stanza_mt = st.stanza_mt;

local tostring = tostring;

local t_insert = table.insert;

local t_concat = table.concat;

local t_remove = table.remove;

local setmetatable = setmetatable;

local default_log = require "util.logger".init("xmppstream");

-- COMPAT: w/LuaExpat 1.1.0

local lxp_supports_doctype = pcall(lxp.new, { StartDoctypeDecl = false });

if not lxp_supports_doctype then

	default_log("warn", "The version of LuaExpat on your system leaves Prosody "

		.."vulnerable to denial-of-service attacks. You should upgrade to "

		.."LuaExpat 1.1.1 or higher as soon as possible. See "

		.."http://prosody.im/doc/depends#luaexpat for more information.");

end

local error = error;

module "xmppstream"

local new_parser = lxp.new;

local ns_prefixes = {

	["http://www.w3.org/XML/1998/namespace"] = "xml";

};

local xmlns_streams = "http://etherx.jabber.org/streams";

local ns_separator = "\1";

local ns_pattern = "^([^"..ns_separator.."]*)"..ns_separator.."?(.*)$";

_M.ns_separator = ns_separator;

_M.ns_pattern = ns_pattern;

function new_sax_handlers(session, stream_callbacks)

	local xml_handlers = {};

	local log = session.log or default_log;

	local cb_streamopened = stream_callbacks.streamopened;

	local cb_streamclosed = stream_callbacks.streamclosed;

	local cb_error = stream_callbacks.error or function(session, e) error("XML stream error: "..tostring(e)); end;

	local cb_handlestanza = stream_callbacks.handlestanza;

	local stream_ns = stream_callbacks.stream_ns or xmlns_streams;

	local stream_tag = stream_callbacks.stream_tag or "stream";

	if stream_ns ~= "" then

		stream_tag = stream_ns..ns_separator..stream_tag;

	end

	local stream_error_tag = stream_ns..ns_separator..(stream_callbacks.error_tag or "error");

	local stream_default_ns = stream_callbacks.default_ns;

	local stack = {};

	local chardata, stanza = {};

	local non_streamns_depth = 0;

	function xml_handlers:StartElement(tagname, attr)

		if stanza and #chardata > 0 then

			-- We have some character data in the buffer

			t_insert(stanza, t_concat(chardata));

			chardata = {};

		end

		local curr_ns,name = tagname:match(ns_pattern);

		if name == "" then

			curr_ns, name = "", curr_ns;

		end

		if curr_ns ~= stream_default_ns or non_streamns_depth > 0 then

			attr.xmlns = curr_ns;

			non_streamns_depth = non_streamns_depth + 1;

		end

		-- FIXME !!!!!

		for i=1,#attr do

			local k = attr[i];

			attr[i] = nil;

			local ns, nm = k:match(ns_pattern);

			if nm ~= "" then

				ns = ns_prefixes[ns];

				if ns then

					attr[ns..":"..nm] = attr[k];

					attr[k] = nil;

				end

			end

		end

		if not stanza then --if we are not currently inside a stanza

			if session.notopen then

				if tagname == stream_tag then

					non_streamns_depth = 0;

					if cb_streamopened then

						cb_streamopened(session, attr);

					end

				else

					-- Garbage before stream?

					cb_error(session, "no-stream");

				end

				return;

			end

			if curr_ns == "jabber:client" and name ~= "iq" and name ~= "presence" and name ~= "message" then

				cb_error(session, "invalid-top-level-element");

			end

			stanza = setmetatable({ name = name, attr = attr, tags = {} }, stanza_mt);

		else -- we are inside a stanza, so add a tag

			t_insert(stack, stanza);

			local oldstanza = stanza;

			stanza = setmetatable({ name = name, attr = attr, tags = {} }, stanza_mt);

			t_insert(oldstanza, stanza);

			t_insert(oldstanza.tags, stanza);

		end

	end

	function xml_handlers:CharacterData(data)

		if stanza then

			t_insert(chardata, data);

		end

	end

	function xml_handlers:EndElement(tagname)

		if non_streamns_depth > 0 then

			non_streamns_depth = non_streamns_depth - 1;

		end

		if stanza then

			if #chardata > 0 then

				-- We have some character data in the buffer

				t_insert(stanza, t_concat(chardata));

				chardata = {};

			end

			-- Complete stanza

			if #stack == 0 then

				if tagname ~= stream_error_tag then

					cb_handlestanza(session, stanza);

				else

					cb_error(session, "stream-error", stanza);

				end

				stanza = nil;

			else

				stanza = t_remove(stack);

			end

		else

			if tagname == stream_tag then

				if cb_streamclosed then

					cb_streamclosed(session);

				end

			else

				local curr_ns,name = tagname:match(ns_pattern);

				if name == "" then

					curr_ns, name = "", curr_ns;

				end

				cb_error(session, "parse-error", "unexpected-element-close", name);

			end

			stanza, chardata = nil, {};

			stack = {};

		end

	end

	local function restricted_handler(parser)

		cb_error(session, "parse-error", "restricted-xml", "Restricted XML, see RFC 6120 section 11.1.");

		if not parser.stop or not parser:stop() then

			error("Failed to abort parsing");

		end

	end

	if lxp_supports_doctype then

		xml_handlers.StartDoctypeDecl = restricted_handler;

	end

	xml_handlers.Comment = restricted_handler;

	xml_handlers.ProcessingInstruction = restricted_handler;

	local function reset()

		stanza, chardata = nil, {};

		stack = {};

	end

	local function set_session(stream, new_session)

		session = new_session;

		log = new_session.log or default_log;

	end

	return xml_handlers, { reset = reset, set_session = set_session };

end

function new(session, stream_callbacks)

	local handlers, meta = new_sax_handlers(session, stream_callbacks);

	local parser = new_parser(handlers, ns_separator);

	local parse = parser.parse;

	return {

		reset = function ()

			parser = new_parser(handlers, ns_separator);

			parse = parser.parse;

			meta.reset();

		end,

		feed = function (self, data)

			return parse(parser, data);

		end,

		set_session = meta.set_session;

	};

end

return _M;