mod_bosh: Validate 'to' host (see #343)

[prosody.git] / plugins / mod_bosh.lua

-- 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.
--

module:set_global(); -- Global module

local hosts = _G.hosts;
local new_xmpp_stream = require "util.xmppstream".new;
local sm = require "core.sessionmanager";
local sm_destroy_session = sm.destroy_session;
local new_uuid = require "util.uuid".generate;
local core_process_stanza = prosody.core_process_stanza;
local st = require "util.stanza";
local logger = require "util.logger";
local log = logger.init("mod_bosh");
local initialize_filters = require "util.filters".initialize;
local math_min = math.min;
local xpcall, tostring, type = xpcall, tostring, type;
local traceback = debug.traceback;
local nameprep = require "util.encodings".stringprep.nameprep;

local xmlns_streams = "http://etherx.jabber.org/streams";
local xmlns_xmpp_streams = "urn:ietf:params:xml:ns:xmpp-streams";
local xmlns_bosh = "http://jabber.org/protocol/httpbind"; -- (hard-coded into a literal in session.send)

local stream_callbacks = {
        stream_ns = xmlns_bosh, stream_tag = "body", default_ns = "jabber:client" };

local BOSH_DEFAULT_HOLD = module:get_option_number("bosh_default_hold", 1);
local BOSH_DEFAULT_INACTIVITY = module:get_option_number("bosh_max_inactivity", 60);
local BOSH_DEFAULT_POLLING = module:get_option_number("bosh_max_polling", 5);
local BOSH_DEFAULT_REQUESTS = module:get_option_number("bosh_max_requests", 2);
local bosh_max_wait = module:get_option_number("bosh_max_wait", 120);

local consider_bosh_secure = module:get_option_boolean("consider_bosh_secure");
local cross_domain = module:get_option("cross_domain_bosh", false);

if cross_domain == true then cross_domain = "*"; end
if type(cross_domain) == "table" then cross_domain = table.concat(cross_domain, ", "); end

local trusted_proxies = module:get_option_set("trusted_proxies", {"127.0.0.1"})._items;

local function get_ip_from_request(request)
        local ip = request.conn:ip();
        local forwarded_for = request.headers.x_forwarded_for;
        if forwarded_for then
                forwarded_for = forwarded_for..", "..ip;
                for forwarded_ip in forwarded_for:gmatch("[^%s,]+") do
                        if not trusted_proxies[forwarded_ip] then
                                ip = forwarded_ip;
                        end
                end
        end
        return ip;
end

local t_insert, t_remove, t_concat = table.insert, table.remove, table.concat;
local os_time = os.time;

-- All sessions, and sessions that have no requests open
local sessions, inactive_sessions = module:shared("sessions", "inactive_sessions");

-- Used to respond to idle sessions (those with waiting requests)
local waiting_requests = module:shared("waiting_requests");
function on_destroy_request(request)
        log("debug", "Request destroyed: %s", tostring(request));
        waiting_requests[request] = nil;
        local session = sessions[request.context.sid];
        if session then
                local requests = session.requests;
                for i, r in ipairs(requests) do
                        if r == request then
                                t_remove(requests, i);
                                break;
                        end
                end

                -- If this session now has no requests open, mark it as inactive
                local max_inactive = session.bosh_max_inactive;
                if max_inactive and #requests == 0 then
                        inactive_sessions[session] = os_time() + max_inactive;
                        (session.log or log)("debug", "BOSH session marked as inactive (for %ds)", max_inactive);
                end
        end
end

local function set_cross_domain_headers(response)
        local headers = response.headers;
        headers.access_control_allow_methods = "GET, POST, OPTIONS";
        headers.access_control_allow_headers = "Content-Type";
        headers.access_control_max_age = "7200";
        headers.access_control_allow_origin = cross_domain;
        return response;
end

function handle_OPTIONS(event)
        if cross_domain and event.request.headers.origin then
                set_cross_domain_headers(event.response);
        end
        return "";
end

function handle_POST(event)
        log("debug", "Handling new request %s: %s\n----------", tostring(event.request), tostring(event.request.body));

        local request, response = event.request, event.response;
        response.on_destroy = on_destroy_request;
        local body = request.body;

        local context = { request = request, response = response, notopen = true };
        local stream = new_xmpp_stream(context, stream_callbacks);
        response.context = context;

        local headers = response.headers;
        headers.content_type = "text/xml; charset=utf-8";

        if cross_domain and event.request.headers.origin then
                set_cross_domain_headers(response);
        end

        -- stream:feed() calls the stream_callbacks, so all stanzas in
        -- the body are processed in this next line before it returns.
        -- In particular, the streamopened() stream callback is where
        -- much of the session logic happens, because it's where we first
        -- get to see the 'sid' of this request.
        local ok, err = stream:feed(body);
        if not ok then
                module:log("warn", "Error parsing BOSH payload; %s", err)
                local close_reply = st.stanza("body", { xmlns = xmlns_bosh, type = "terminate",
                        ["xmlns:stream"] = xmlns_streams, condition = "bad-request" });
                return tostring(close_reply);
        end

        -- Stanzas (if any) in the request have now been processed, and
        -- we take care of the high-level BOSH logic here, including
        -- giving a response or putting the request "on hold".
        local session = sessions[context.sid];
        if session then
                -- Session was marked as inactive, since we have
                -- a request open now, unmark it
                if inactive_sessions[session] and #session.requests > 0 then
                        inactive_sessions[session] = nil;
                end

                local r = session.requests;
                log("debug", "Session %s has %d out of %d requests open", context.sid, #r, session.bosh_hold);
                log("debug", "and there are %d things in the send_buffer:", #session.send_buffer);
                if #r > session.bosh_hold then
                        -- We are holding too many requests, send what's in the buffer,
                        log("debug", "We are holding too many requests, so...");
                        if #session.send_buffer > 0 then
                                log("debug", "...sending what is in the buffer")
                                session.send(t_concat(session.send_buffer));
                                session.send_buffer = {};
                        else
                                -- or an empty response
                                log("debug", "...sending an empty response");
                                session.send("");
                        end
                elseif #session.send_buffer > 0 then
                        log("debug", "Session has data in the send buffer, will send now..");
                        local resp = t_concat(session.send_buffer);
                        session.send_buffer = {};
                        session.send(resp);
                end

                if not response.finished then
                        -- We're keeping this request open, to respond later
                        log("debug", "Have nothing to say, so leaving request unanswered for now");
                        if session.bosh_wait then
                                waiting_requests[response] = os_time() + session.bosh_wait;
                        end
                end

                if session.bosh_terminate then
                        session.log("debug", "Closing session with %d requests open", #session.requests);
                        session:close();
                        return nil;
                else
                        return true; -- Inform http server we shall reply later
                end
        elseif response.finished then
                return; -- A response has been sent already
        end
        module:log("warn", "Unable to associate request with a session (incomplete request?)");
        local close_reply = st.stanza("body", { xmlns = xmlns_bosh, type = "terminate",
                ["xmlns:stream"] = xmlns_streams, condition = "item-not-found" });
        return tostring(close_reply) .. "\n";
end


local function bosh_reset_stream(session) session.notopen = true; end

local stream_xmlns_attr = { xmlns = "urn:ietf:params:xml:ns:xmpp-streams" };

local function bosh_close_stream(session, reason)
        (session.log or log)("info", "BOSH client disconnected");

        local close_reply = st.stanza("body", { xmlns = xmlns_bosh, type = "terminate",
                ["xmlns:stream"] = xmlns_streams });


        if reason then
                close_reply.attr.condition = "remote-stream-error";
                if type(reason) == "string" then -- assume stream error
                        close_reply:tag("stream:error")
                                :tag(reason, {xmlns = xmlns_xmpp_streams});
                elseif type(reason) == "table" then
                        if reason.condition then
                                close_reply:tag("stream:error")
                                        :tag(reason.condition, stream_xmlns_attr):up();
                                if reason.text then
                                        close_reply:tag("text", stream_xmlns_attr):text(reason.text):up();
                                end
                                if reason.extra then
                                        close_reply:add_child(reason.extra);
                                end
                        elseif reason.name then -- a stanza
                                close_reply = reason;
                        end
                end
                log("info", "Disconnecting client, <stream:error> is: %s", tostring(close_reply));
        end

        local response_body = tostring(close_reply);
        for _, held_request in ipairs(session.requests) do
                held_request:send(response_body);
        end
        sessions[session.sid] = nil;
        inactive_sessions[session] = nil;
        sm_destroy_session(session);
end

-- Handle the <body> tag in the request payload.
function stream_callbacks.streamopened(context, attr)
        local request, response = context.request, context.response;
        local sid = attr.sid;
        log("debug", "BOSH body open (sid: %s)", sid or "<none>");
        if not sid then
                -- New session request
                context.notopen = nil; -- Signals that we accept this opening tag

                -- TODO: Sanity checks here (rid, to, known host, etc.)
                local to_host = nameprep(attr.to);
                if not to_host then
                        log("debug", "BOSH client tried to connect to invalid host: %s", tostring(attr.to));
                        local close_reply = st.stanza("body", { xmlns = xmlns_bosh, type = "terminate",
                                ["xmlns:stream"] = xmlns_streams, condition = "improper-addressing" });
                        response:send(tostring(close_reply));
                        return;
                elseif not hosts[to_host] then
                        -- Unknown host
                        log("debug", "BOSH client tried to connect to unknown host: %s", tostring(attr.to));
                        local close_reply = st.stanza("body", { xmlns = xmlns_bosh, type = "terminate",
                                ["xmlns:stream"] = xmlns_streams, condition = "host-unknown" });
                        response:send(tostring(close_reply));
                        return;
                end

                -- New session
                sid = new_uuid();
                local session = {
                        type = "c2s_unauthed", conn = {}, sid = sid, rid = tonumber(attr.rid)-1, host = attr.to,
                        bosh_version = attr.ver, bosh_wait = math_min(attr.wait, bosh_max_wait), streamid = sid,
                        bosh_hold = BOSH_DEFAULT_HOLD, bosh_max_inactive = BOSH_DEFAULT_INACTIVITY,
                        requests = { }, send_buffer = {}, reset_stream = bosh_reset_stream,
                        close = bosh_close_stream, dispatch_stanza = core_process_stanza, notopen = true,
                        log = logger.init("bosh"..sid), secure = consider_bosh_secure or request.secure,
                        ip = get_ip_from_request(request);
                };
                sessions[sid] = session;

                local filter = initialize_filters(session);

                session.log("debug", "BOSH session created for request from %s", session.ip);
                log("info", "New BOSH session, assigned it sid '%s'", sid);

                hosts[session.host].events.fire_event("bosh-session", { session = session, request = request });

                -- Send creation response
                local creating_session = true;

                local r = session.requests;
                function session.send(s)
                        -- We need to ensure that outgoing stanzas have the jabber:client xmlns
                        if s.attr and not s.attr.xmlns then
                                s = st.clone(s);
                                s.attr.xmlns = "jabber:client";
                        end
                        s = filter("stanzas/out", s);
                        --log("debug", "Sending BOSH data: %s", tostring(s));
                        if not s then return true end
                        t_insert(session.send_buffer, tostring(s));

                        local oldest_request = r[1];
                        if oldest_request and not session.bosh_processing then
                                log("debug", "We have an open request, so sending on that");
                                local body_attr = { xmlns = "http://jabber.org/protocol/httpbind",
                                        ["xmlns:stream"] = "http://etherx.jabber.org/streams";
                                        type = session.bosh_terminate and "terminate" or nil;
                                        sid = sid;
                                };
                                if creating_session then
                                        creating_session = nil;
                                        body_attr.inactivity = tostring(BOSH_DEFAULT_INACTIVITY);
                                        body_attr.polling = tostring(BOSH_DEFAULT_POLLING);
                                        body_attr.requests = tostring(BOSH_DEFAULT_REQUESTS);
                                        body_attr.wait = tostring(session.bosh_wait);
                                        body_attr.hold = tostring(session.bosh_hold);
                                        body_attr.authid = sid;
                                        body_attr.secure = "true";
                                        body_attr.ver  = '1.6';
                                        body_attr.from = session.host;
                                        body_attr["xmlns:xmpp"] = "urn:xmpp:xbosh";
                                        body_attr["xmpp:version"] = "1.0";
                                end
                                oldest_request:send(st.stanza("body", body_attr):top_tag()..t_concat(session.send_buffer).."</body>");
                                session.send_buffer = {};
                        end
                        return true;
                end
                request.sid = sid;
        end

        local session = sessions[sid];
        if not session then
                -- Unknown sid
                log("info", "Client tried to use sid '%s' which we don't know about", sid);
                response:send(tostring(st.stanza("body", { xmlns = xmlns_bosh, type = "terminate", condition = "item-not-found" })));
                context.notopen = nil;
                return;
        end

        if session.rid then
                local rid = tonumber(attr.rid);
                local diff = rid - session.rid;
                if diff > 1 then
                        session.log("warn", "rid too large (means a request was lost). Last rid: %d New rid: %s", session.rid, attr.rid);
                elseif diff <= 0 then
                        -- Repeated, ignore
                        session.log("debug", "rid repeated, ignoring: %s (diff %d)", session.rid, diff);
                        context.notopen = nil;
                        context.ignore = true;
                        context.sid = sid;
                        t_insert(session.requests, response);
                        return;
                end
                session.rid = rid;
        end

        if attr.type == "terminate" then
                -- Client wants to end this session, which we'll do
                -- after processing any stanzas in this request
                session.bosh_terminate = true;
        end

        context.notopen = nil; -- Signals that we accept this opening tag
        t_insert(session.requests, response);
        context.sid = sid;
        session.bosh_processing = true; -- Used to suppress replies until processing of this request is done

        if session.notopen then
                local features = st.stanza("stream:features");
                hosts[session.host].events.fire_event("stream-features", { origin = session, features = features });
                session.send(features);
                session.notopen = nil;
        end
end

local function handleerr(err) log("error", "Traceback[bosh]: %s", traceback(tostring(err), 2)); end
function stream_callbacks.handlestanza(context, stanza)
        if context.ignore then return; end
        log("debug", "BOSH stanza received: %s\n", stanza:top_tag());
        local session = sessions[context.sid];
        if session then
                if stanza.attr.xmlns == xmlns_bosh then
                        stanza.attr.xmlns = nil;
                end
                stanza = session.filter("stanzas/in", stanza);
                if stanza then
                        return xpcall(function () return core_process_stanza(session, stanza) end, handleerr);
                end
        end
end

function stream_callbacks.streamclosed(context)
        local session = sessions[context.sid];
        if session then
                session.bosh_processing = false;
                if #session.send_buffer > 0 then
                        session.send("");
                end
        end
end

function stream_callbacks.error(context, error)
        log("debug", "Error parsing BOSH request payload; %s", error);
        if not context.sid then
                local response = context.response;
                response.status_code = 400;
                response:send();
                return;
        end

        local session = sessions[context.sid];
        if error == "stream-error" then -- Remote stream error, we close normally
                session:close();
        else
                session:close({ condition = "bad-format", text = "Error processing stream" });
        end
end

local dead_sessions = module:shared("dead_sessions");
function on_timer()
        -- log("debug", "Checking for requests soon to timeout...");
        -- Identify requests timing out within the next few seconds
        local now = os_time() + 3;
        for request, reply_before in pairs(waiting_requests) do
                if reply_before <= now then
                        log("debug", "%s was soon to timeout (at %d, now %d), sending empty response", tostring(request), reply_before, now);
                        -- Send empty response to let the
                        -- client know we're still here
                        if request.conn then
                                sessions[request.context.sid].send("");
                        end
                end
        end

        now = now - 3;
        local n_dead_sessions = 0;
        for session, close_after in pairs(inactive_sessions) do
                if close_after < now then
                        (session.log or log)("debug", "BOSH client inactive too long, destroying session at %d", now);
                        sessions[session.sid]  = nil;
                        inactive_sessions[session] = nil;
                        n_dead_sessions = n_dead_sessions + 1;
                        dead_sessions[n_dead_sessions] = session;
                end
        end

        for i=1,n_dead_sessions do
                local session = dead_sessions[i];
                dead_sessions[i] = nil;
                sm_destroy_session(session, "BOSH client silent for over "..session.bosh_max_inactive.." seconds");
        end
        return 1;
end
module:add_timer(1, on_timer);


local GET_response = {
        headers = {
                content_type = "text/html";
        };
        body = [[<html><body>
        <p>It works! Now point your BOSH client to this URL to connect to Prosody.</p>
        <p>For more information see <a href="http://prosody.im/doc/setting_up_bosh">Prosody: Setting up BOSH</a>.</p>
        </body></html>]];
};

function module.add_host(module)
        module:depends("http");
        module:provides("http", {
                default_path = "/http-bind";
                route = {
                        ["GET"] = GET_response;
                        ["GET /"] = GET_response;
                        ["OPTIONS"] = handle_OPTIONS;
                        ["OPTIONS /"] = handle_OPTIONS;
                        ["POST"] = handle_POST;
                        ["POST /"] = handle_POST;
                };
        });
end