mod_websocket: Determine whether to use a self-closing stream tag, based on the client's initial data
-- Prosody IM
-- Copyright (C) 2008-2010 Matthew Wild
-- Copyright (C) 2008-2010 Waqas Hussain
-- Copyright (C) 2012 Florian Zeitz
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--
module:set_global();
local add_task = require "util.timer".add_task;
local new_xmpp_stream = require "util.xmppstream".new;
local nameprep = require "util.encodings".stringprep.nameprep;
local sessionmanager = require "core.sessionmanager";
local st = require "util.stanza";
local sm_new_session, sm_destroy_session = sessionmanager.new_session, sessionmanager.destroy_session;
local uuid_generate = require "util.uuid".generate;
local sha1 = require "util.hashes".sha1;
local base64 = require "util.encodings".base64.encode;
local band = require "bit".band;
local bxor = require "bit".bxor;
local xpcall, tostring, type = xpcall, tostring, type;
local traceback = debug.traceback;
local xmlns_xmpp_streams = "urn:ietf:params:xml:ns:xmpp-streams";
local log = module._log;
local c2s_timeout = module:get_option_number("c2s_timeout");
local stream_close_timeout = module:get_option_number("c2s_close_timeout", 5);
local opt_keepalives = module:get_option_boolean("tcp_keepalives", false);
local cross_domain = module:get_option("cross_domain_websocket");
if cross_domain then
if cross_domain == true then
cross_domain = "*";
elseif type(cross_domain) == "table" then
cross_domain = table.concat(cross_domain, ", ");
end
if type(cross_domain) ~= "string" then
cross_domain = nil;
end
end
local sessions = module:shared("sessions");
local core_process_stanza = prosody.core_process_stanza;
local stream_callbacks = { default_ns = "jabber:client", handlestanza = core_process_stanza };
local listener = {};
-- Websocket helpers
local function parse_frame(frame)
local result = {};
local pos = 1;
local length_bytes = 0;
local counter = 0;
local tmp_byte;
if #frame < 2 then return; end
tmp_byte = string.byte(frame, pos);
result.FIN = band(tmp_byte, 0x80) > 0;
result.RSV1 = band(tmp_byte, 0x40) > 0;
result.RSV2 = band(tmp_byte, 0x20) > 0;
result.RSV3 = band(tmp_byte, 0x10) > 0;
result.opcode = band(tmp_byte, 0x0F);
pos = pos + 1;
tmp_byte = string.byte(frame, pos);
result.MASK = band(tmp_byte, 0x80) > 0;
result.length = band(tmp_byte, 0x7F);
if result.length == 126 then
length_bytes = 2;
result.length = 0;
elseif result.length == 127 then
length_bytes = 8;
result.length = 0;
end
if #frame < (2 + length_bytes) then return; end
for i = 1, length_bytes do
pos = pos + 1;
result.length = result.length * 256 + string.byte(frame, pos);
end
if #frame < (2 + length_bytes + (result.MASK and 4 or 0) + result.length) then return; end
if result.MASK then
result.key = {string.byte(frame, pos+1), string.byte(frame, pos+2),
string.byte(frame, pos+3), string.byte(frame, pos+4)}
pos = pos + 5;
result.data = "";
for i = pos, pos + result.length - 1 do
result.data = result.data .. string.char(bxor(result.key[counter+1], string.byte(frame, i)));
counter = (counter + 1) % 4;
end
else
result.data = frame:sub(pos + 1, pos + result.length);
end
return result, 2 + length_bytes + (result.MASK and 4 or 0) + result.length;
end
local function build_frame(desc)
local length;
local result = "";
local data = desc.data or "";
result = result .. string.char(0x80 * (desc.FIN and 1 or 0) + desc.opcode);
length = #data;
if length <= 125 then -- 7-bit length
result = result .. string.char(length);
elseif length <= 0xFFFF then -- 2-byte length
result = result .. string.char(126);
result = result .. string.char(length/0x100) .. string.char(length%0x100);
else -- 8-byte length
result = result .. string.char(127);
for i = 7, 0, -1 do
result = result .. string.char(( length / (2^(8*i)) ) % 0x100);
end
end
result = result .. data;
return result;
end
--- Stream events handlers
local stream_xmlns_attr = {xmlns='urn:ietf:params:xml:ns:xmpp-streams'};
local default_stream_attr = { ["xmlns:stream"] = "http://etherx.jabber.org/streams", xmlns = stream_callbacks.default_ns, version = "1.0", id = "" };
function stream_callbacks.streamopened(session, attr)
local send = session.send;
session.host = nameprep(attr.to);
if not session.host then
session:close{ condition = "improper-addressing",
text = "A valid 'to' attribute is required on stream headers" };
return;
end
session.version = tonumber(attr.version) or 0;
session.streamid = uuid_generate();
(session.log or session)("debug", "Client sent opening <stream:stream> to %s", session.host);
if not hosts[session.host] then
-- We don't serve this host...
session:close{ condition = "host-unknown", text = "This server does not serve "..tostring(session.host)};
return;
end
-- COMPAT: Some current client implementations need this to be self-closing
if session.self_closing_stream then
send("<?xml version='1.0'?>"..tostring(st.stanza("stream:stream", {
xmlns = 'jabber:client', ["xmlns:stream"] = 'http://etherx.jabber.org/streams';
id = session.streamid, from = session.host, version = '1.0', ["xml:lang"] = 'en' })));
else
send("<?xml version='1.0'?>"..st.stanza("stream:stream", {
xmlns = 'jabber:client', ["xmlns:stream"] = 'http://etherx.jabber.org/streams';
id = session.streamid, from = session.host, version = '1.0', ["xml:lang"] = 'en' }):top_tag());
end
(session.log or log)("debug", "Sent reply <stream:stream> to client");
session.notopen = nil;
-- If session.secure is *false* (not nil) then it means we /were/ encrypting
-- since we now have a new stream header, session is secured
if session.secure == false then
session.secure = true;
end
local features = st.stanza("stream:features");
hosts[session.host].events.fire_event("stream-features", { origin = session, features = features });
module:fire_event("stream-features", session, features);
send(features);
end
function stream_callbacks.streamclosed(session)
session.log("debug", "Received </stream:stream>");
session:close(false);
end
function stream_callbacks.error(session, error, data)
if error == "no-stream" then
session.log("debug", "Invalid opening stream header");
session:close("invalid-namespace");
elseif error == "parse-error" then
(session.log or log)("debug", "Client XML parse error: %s", tostring(data));
session:close("not-well-formed");
elseif error == "stream-error" then
local condition, text = "undefined-condition";
for child in data:children() do
if child.attr.xmlns == xmlns_xmpp_streams then
if child.name ~= "text" then
condition = child.name;
else
text = child:get_text();
end
if condition ~= "undefined-condition" and text then
break;
end
end
end
text = condition .. (text and (" ("..text..")") or "");
session.log("info", "Session closed by remote with error: %s", text);
session:close(nil, text);
end
end
local function handleerr(err) log("error", "Traceback[c2s]: %s: %s", tostring(err), traceback()); end
function stream_callbacks.handlestanza(session, stanza)
stanza = session.filter("stanzas/in", stanza);
if stanza then
return xpcall(function () return core_process_stanza(session, stanza) end, handleerr);
end
end
--- Session methods
local function session_close(session, reason)
local log = session.log or log;
if session.conn then
if session.notopen then
-- COMPAT: Some current client implementations need this to be self-closing
if session.self_closing_stream then
session.send("<?xml version='1.0'?>"..tostring(st.stanza("stream:stream", default_stream_attr)));
else
session.send("<?xml version='1.0'?>"..st.stanza("stream:stream", default_stream_attr):top_tag());
end
end
if reason then -- nil == no err, initiated by us, false == initiated by client
if type(reason) == "string" then -- assume stream error
log("debug", "Disconnecting client, <stream:error> is: %s", reason);
session.send(st.stanza("stream:error"):tag(reason, {xmlns = 'urn:ietf:params:xml:ns:xmpp-streams' }));
elseif type(reason) == "table" then
if reason.condition then
local stanza = st.stanza("stream:error"):tag(reason.condition, stream_xmlns_attr):up();
if reason.text then
stanza:tag("text", stream_xmlns_attr):text(reason.text):up();
end
if reason.extra then
stanza:add_child(reason.extra);
end
log("debug", "Disconnecting client, <stream:error> is: %s", tostring(stanza));
session.send(stanza);
elseif reason.name then -- a stanza
log("debug", "Disconnecting client, <stream:error> is: %s", tostring(reason));
session.send(reason);
end
end
end
session.send("</stream:stream>");
function session.send() return false; end
local reason = (reason and (reason.text or reason.condition)) or reason;
session.log("info", "c2s stream for %s closed: %s", session.full_jid or ("<"..session.ip..">"), reason or "session closed");
-- Authenticated incoming stream may still be sending us stanzas, so wait for </stream:stream> from remote
local conn = session.conn;
if reason == nil and not session.notopen and session.type == "c2s" then
-- Grace time to process data from authenticated cleanly-closed stream
add_task(stream_close_timeout, function ()
if not session.destroyed then
session.log("warn", "Failed to receive a stream close response, closing connection anyway...");
sm_destroy_session(session, reason);
conn:close();
end
end);
else
sm_destroy_session(session, reason);
conn:close();
end
end
end
module:hook_global("user-deleted", function(event)
local username, host = event.username, event.host;
local user = hosts[host].sessions[username];
if user and user.sessions then
for jid, session in pairs(user.sessions) do
session:close{ condition = "not-authorized", text = "Account deleted" };
end
end
end, 200);
--- Port listener
function listener.onconnect(conn)
local session = sm_new_session(conn);
sessions[conn] = session;
session.log("info", "Client connected");
-- Client is using legacy SSL (otherwise mod_tls sets this flag)
if conn:ssl() then
session.secure = true;
end
if opt_keepalives then
conn:setoption("keepalive", opt_keepalives);
end
session.close = session_close;
session.conn.starttls = nil;
local stream = new_xmpp_stream(session, stream_callbacks);
session.stream = stream;
session.notopen = true;
function session.reset_stream()
session.notopen = true;
session.stream:reset();
end
local function websocket_close(code, message)
local data = string.char(code/0x100) .. string.char(code%0x100) .. message;
conn:write(build_frame({opcode = 0x8, FIN = true, data = data}));
conn:close();
end
local filter = session.filter;
local dataBuffer;
local function handle_frame(frame)
module:log("debug", "Websocket received: %s (%i bytes)", frame.data, #frame.data);
-- Error cases
if frame.RSV1 or frame.RSV2 or frame.RSV3 then -- Reserved bits non zero
websocket_close(1002, "Reserved bits not zero");
return false;
end
if frame.opcode >= 0x8 and frame.length > 125 then -- Control frame with too much payload
websocket_close(1002, "Payload too large");
return false;
end
if frame.opcode >= 0x8 and not frame.FIN then -- Fragmented control frame
websocket_close(1002, "Fragmented control frame");
return false;
end
if (frame.opcode > 0x2 and frame.opcode < 0x8) or (frame.opcode > 0xA) then
websocket_close(1002, "Reserved opcode");
return false;
end
if frame.opcode == 0x0 and not dataBuffer then
websocket_close(1002, "Unexpected continuation frame");
return false;
end
if (frame.opcode == 0x1 or frame.opcode == 0x2) and dataBuffer then
websocket_close(1002, "Continuation frame expected");
return false;
end
-- Valid cases
if frame.opcode == 0x0 then -- Continuation frame
dataBuffer = dataBuffer .. frame.data;
elseif frame.opcode == 0x1 then -- Text frame
dataBuffer = frame.data;
elseif frame.opcode == 0x2 then -- Binary frame
websocket_close(1003, "Only text frames are supported");
return false;
elseif frame.opcode == 0x8 then -- Close request
websocket_close(1000, "Goodbye");
return false;
elseif frame.opcode == 0x9 then -- Ping frame
frame.opcode = 0xA;
conn:write(build_frame(frame));
return true;
else
log("warn", "Received frame with unsupported opcode %i", frame.opcode);
return true;
end
if frame.FIN then
data = dataBuffer;
dataBuffer = nil;
-- COMPAT: Some current client implementations send a self-closing <stream:stream>
data, session.self_closing_stream = data:gsub("^(<stream:stream.*)/>$", "%1>");
session.self_closing_stream = (session.self_closing_stream == 1)
data = filter("bytes/in", data);
if data then
local ok, err = stream:feed(data);
if ok then return; end
log("debug", "Received invalid XML (%s) %d bytes: %s", tostring(err), #data, data:sub(1, 300):gsub("[\r\n]+", " "):gsub("[%z\1-\31]", "_"));
session:close("not-well-formed");
end
end
return true;
end
local frameBuffer = "";
function session.data(data)
frameBuffer = frameBuffer .. data;
local frame, length = parse_frame(frameBuffer);
while frame do
frameBuffer = frameBuffer:sub(length + 1);
if not handle_frame(frame) then return; end
frame, length = parse_frame(frameBuffer);
end
end
function session.send(s)
conn:write(build_frame({ FIN = true, opcode = 0x01, data = tostring(s)}));
end
if c2s_timeout then
add_task(c2s_timeout, function ()
if session.type == "c2s_unauthed" then
session:close("connection-timeout");
end
end);
end
session.dispatch_stanza = stream_callbacks.handlestanza;
end
function listener.onincoming(conn, data)
local session = sessions[conn];
if session then
session.data(data);
else
listener.onconnect(conn, data);
session = sessions[conn];
session.data(data);
end
end
function listener.ondisconnect(conn, err)
local session = sessions[conn];
if session then
(session.log or log)("info", "Client disconnected: %s", err or "connection closed");
sm_destroy_session(session, err);
sessions[conn] = nil;
end
end
function listener.associate_session(conn, session)
sessions[conn] = session;
end
function handle_request(event, path)
local request, response = event.request, event.response;
if not request.headers.sec_websocket_key then
response.headers.content_type = "text/html";
return [[<!DOCTYPE html><html><head><title>Websocket</title></head><body>
<p>It works! Now point your WebSocket client to this URL to connect to Prosody.</p>
</body></html>]];
end
local wants_xmpp = false;
(request.headers.sec_websocket_protocol or ""):gsub("([^,]*),?", function (proto)
if proto == "xmpp" then wants_xmpp = true; end
end);
if not wants_xmpp then
return 501;
end
response.conn:setlistener(listener);
response.status = "101 Switching Protocols";
response.headers.Upgrade = "websocket";
response.headers.Connection = "Upgrade";
response.headers.Sec_WebSocket_Accept = base64(sha1(request.headers.sec_websocket_key .. "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"));
response.headers.Sec_WebSocket_Protocol = "xmpp";
response.headers.Access_Control_Allow_Origin = cross_domain;
return "";
end
function module.add_host(module)
module:depends("http");
module:provides("http", {
name = "xmpp-websocket";
route = {
["GET"] = handle_request;
["GET /"] = handle_request;
};
});
end