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    1 -- XEP-0198: Stream Management for Prosody IM
    2 --
    3 -- Copyright (C) 2010-2015 Matthew Wild
    4 -- Copyright (C) 2010 Waqas Hussain
    5 -- Copyright (C) 2012-2021 Kim Alvefur
    6 -- Copyright (C) 2012 Thijs Alkemade
    7 -- Copyright (C) 2014 Florian Zeitz
    8 -- Copyright (C) 2016-2020 Thilo Molitor
    9 --
   10 -- This project is MIT/X11 licensed. Please see the
   11 -- COPYING file in the source package for more information.
   12 --
   13 
   14 local st = require "util.stanza";
   15 local dep = require "util.dependencies";
   16 local cache = dep.softreq("util.cache");    -- only available in prosody 0.10+
   17 local uuid_generate = require "util.uuid".generate;
   18 local jid = require "util.jid";
   19 
   20 local t_remove = table.remove;
   21 local math_min = math.min;
   22 local math_max = math.max;
   23 local os_time = os.time;
   24 local tonumber, tostring = tonumber, tostring;
   25 local add_filter = require "util.filters".add_filter;
   26 local timer = require "util.timer";
   27 local datetime = require "util.datetime";
   28 
   29 local xmlns_mam2 = "urn:xmpp:mam:2";
   30 local xmlns_sm2 = "urn:xmpp:sm:2";
   31 local xmlns_sm3 = "urn:xmpp:sm:3";
   32 local xmlns_errors = "urn:ietf:params:xml:ns:xmpp-stanzas";
   33 local xmlns_delay = "urn:xmpp:delay";
   34 
   35 local sm2_attr = { xmlns = xmlns_sm2 };
   36 local sm3_attr = { xmlns = xmlns_sm3 };
   37 
   38 local resume_timeout = module:get_option_number("smacks_hibernation_time", 600);
   39 local s2s_smacks = module:get_option_boolean("smacks_enabled_s2s", true);
   40 local s2s_resend = module:get_option_boolean("smacks_s2s_resend", false);
   41 local max_unacked_stanzas = module:get_option_number("smacks_max_unacked_stanzas", 0);
   42 local max_inactive_unacked_stanzas = module:get_option_number("smacks_max_inactive_unacked_stanzas", 256);
   43 local delayed_ack_timeout = module:get_option_number("smacks_max_ack_delay", 30);
   44 local max_hibernated_sessions = module:get_option_number("smacks_max_hibernated_sessions", 10);
   45 local max_old_sessions = module:get_option_number("smacks_max_old_sessions", 10);
   46 local core_process_stanza = prosody.core_process_stanza;
   47 local sessionmanager = require"core.sessionmanager";
   48 
   49 assert(max_hibernated_sessions > 0, "smacks_max_hibernated_sessions must be greater than 0");
   50 assert(max_old_sessions > 0, "smacks_max_old_sessions must be greater than 0");
   51 
   52 local c2s_sessions = module:shared("/*/c2s/sessions");
   53 
   54 local function init_session_cache(max_entries, evict_callback)
   55     -- old prosody version < 0.10 (no limiting at all!)
   56     if not cache then
   57         local store = {};
   58         return {
   59             get = function(user, key)
   60                 if not user then return nil; end
   61                 if not key then return nil; end
   62                 return store[key];
   63             end;
   64             set = function(user, key, value)
   65                 if not user then return nil; end
   66                 if not key then return nil; end
   67                 store[key] = value;
   68             end;
   69         };
   70     end
   71 
   72     -- use per user limited cache for prosody >= 0.10
   73     local stores = {};
   74     return {
   75             get = function(user, key)
   76                 if not user then return nil; end
   77                 if not key then return nil; end
   78                 if not stores[user] then
   79                     stores[user] = cache.new(max_entries, evict_callback);
   80                 end
   81                 return stores[user]:get(key);
   82             end;
   83             set = function(user, key, value)
   84                 if not user then return nil; end
   85                 if not key then return nil; end
   86                 if not stores[user] then stores[user] = cache.new(max_entries, evict_callback); end
   87                 stores[user]:set(key, value);
   88                 -- remove empty caches completely
   89                 if not stores[user]:count() then stores[user] = nil; end
   90             end;
   91         };
   92 end
   93 local old_session_registry = init_session_cache(max_old_sessions, nil);
   94 local session_registry = init_session_cache(max_hibernated_sessions, function(resumption_token, session)
   95     if session.destroyed then return true; end      -- destroyed session can always be removed from cache
   96     session.log("warn", "User has too much hibernated sessions, removing oldest session (token: %s)", resumption_token);
   97     -- store old session's h values on force delete
   98     -- save only actual h value and username/host (for security)
   99     old_session_registry.set(session.username, resumption_token, {
  100         h = session.handled_stanza_count,
  101         username = session.username,
  102         host = session.host
  103     });
  104     return true;    -- allow session to be removed from full cache to make room for new one
  105 end);
  106 
  107 local function stoppable_timer(delay, callback)
  108     local stopped = false;
  109     local timer = module:add_timer(delay, function (t)
  110         if stopped then return; end
  111         return callback(t);
  112     end);
  113     if timer and timer.stop then return timer; end      -- new prosody api includes stop() function
  114     return {
  115         stop = function(self) stopped = true end;
  116         timer;
  117     };
  118 end
  119 
  120 local function delayed_ack_function(session, stanza)
  121     -- fire event only if configured to do so and our session is not already hibernated or destroyed
  122     if delayed_ack_timeout > 0 and session.awaiting_ack
  123     and not session.hibernating and not session.destroyed then
  124         session.log("debug", "Firing event 'smacks-ack-delayed', queue = %d",
  125             session.outgoing_stanza_queue and #session.outgoing_stanza_queue or 0);
  126         module:fire_event("smacks-ack-delayed", {origin = session, queue = session.outgoing_stanza_queue, stanza = stanza});
  127     end
  128     session.delayed_ack_timer = nil;
  129 end
  130 
  131 local function can_do_smacks(session, advertise_only)
  132     if session.smacks then return false, "unexpected-request", "Stream management is already enabled"; end
  133 
  134     local session_type = session.type;
  135     if session.username then
  136         if not(advertise_only) and not(session.resource) then -- Fail unless we're only advertising sm
  137             return false, "unexpected-request", "Client must bind a resource before enabling stream management";
  138         end
  139         return true;
  140     elseif s2s_smacks and (session_type == "s2sin" or session_type == "s2sout") then
  141         return true;
  142     end
  143     return false, "service-unavailable", "Stream management is not available for this stream";
  144 end
  145 
  146 module:hook("stream-features",
  147         function (event)
  148             if can_do_smacks(event.origin, true) then
  149                 event.features:tag("sm", sm2_attr):tag("optional"):up():up();
  150                 event.features:tag("sm", sm3_attr):tag("optional"):up():up();
  151             end
  152         end);
  153 
  154 module:hook("s2s-stream-features",
  155         function (event)
  156             if can_do_smacks(event.origin, true) then
  157                 event.features:tag("sm", sm2_attr):tag("optional"):up():up();
  158                 event.features:tag("sm", sm3_attr):tag("optional"):up():up();
  159             end
  160         end);
  161 
  162 local function request_ack_if_needed(session, force, reason, stanza)
  163     local queue = session.outgoing_stanza_queue;
  164     local expected_h = session.last_acknowledged_stanza + #queue;
  165     -- session.log("debug", "*** SMACKS(1) ***: awaiting_ack=%s, hibernating=%s", tostring(session.awaiting_ack), tostring(session.hibernating));
  166     if session.awaiting_ack == nil and not session.hibernating then
  167         local max_unacked = max_unacked_stanzas;
  168         if session.state == "inactive"  then
  169             max_unacked = max_inactive_unacked_stanzas;
  170         end
  171         -- this check of last_requested_h prevents ack-loops if missbehaving clients report wrong
  172         -- stanza counts. it is set when an <r> is really sent (e.g. inside timer), preventing any
  173         -- further requests until a higher h-value would be expected.
  174         -- session.log("debug", "*** SMACKS(2) ***: #queue=%s, max_unacked_stanzas=%s, expected_h=%s, last_requested_h=%s", tostring(#queue), tostring(max_unacked_stanzas), tostring(expected_h), tostring(session.last_requested_h));
  175         if (#queue > max_unacked and expected_h ~= session.last_requested_h) or force then
  176             session.log("debug", "Queuing <r> (in a moment) from %s - #queue=%d", reason, #queue);
  177             session.awaiting_ack = false;
  178             session.awaiting_ack_timer = stoppable_timer(1e-06, function ()
  179                 -- session.log("debug", "*** SMACKS(3) ***: awaiting_ack=%s, hibernating=%s", tostring(session.awaiting_ack), tostring(session.hibernating));
  180                 -- only request ack if needed and our session is not already hibernated or destroyed
  181                 if not session.awaiting_ack and not session.hibernating and not session.destroyed then
  182                     session.log("debug", "Sending <r> (inside timer, before send) from %s - #queue=%d", reason, #queue);
  183                     (session.sends2s or session.send)(st.stanza("r", { xmlns = session.smacks }))
  184                     if session.destroyed then return end -- sending something can trigger destruction
  185                     session.awaiting_ack = true;
  186                     -- expected_h could be lower than this expression e.g. more stanzas added to the queue meanwhile)
  187                     session.last_requested_h = session.last_acknowledged_stanza + #queue;
  188                     session.log("debug", "Sending <r> (inside timer, after send) from %s - #queue=%d", reason, #queue);
  189                     if not session.delayed_ack_timer then
  190                         session.delayed_ack_timer = stoppable_timer(delayed_ack_timeout, function()
  191                             delayed_ack_function(session, nil);     -- we don't know if this is the only new stanza in the queue
  192                         end);
  193                     end
  194                 end
  195             end);
  196         end
  197     end
  198 
  199     -- Trigger "smacks-ack-delayed"-event if we added new (ackable) stanzas to the outgoing queue
  200     -- and there isn't already a timer for this event running.
  201     -- If we wouldn't do this, stanzas added to the queue after the first "smacks-ack-delayed"-event
  202     -- would not trigger this event (again).
  203     if #queue > max_unacked_stanzas and session.awaiting_ack and session.delayed_ack_timer == nil then
  204         session.log("debug", "Calling delayed_ack_function directly (still waiting for ack)");
  205         delayed_ack_function(session, stanza);      -- this is the only new stanza in the queue --> provide it to other modules
  206     end
  207 end
  208 
  209 local function outgoing_stanza_filter(stanza, session)
  210     -- XXX: Normally you wouldn't have to check the xmlns for a stanza as it's
  211     -- supposed to be nil.
  212     -- However, when using mod_smacks with mod_websocket, then mod_websocket's
  213     -- stanzas/out filter can get called before this one and adds the xmlns.
  214     local is_stanza = stanza.attr and
  215         (not stanza.attr.xmlns or stanza.attr.xmlns == 'jabber:client')
  216         and not stanza.name:find":";
  217 
  218     if is_stanza and not stanza._cached then
  219         local queue = session.outgoing_stanza_queue;
  220         local cached_stanza = st.clone(stanza);
  221         cached_stanza._cached = true;
  222 
  223         if cached_stanza and cached_stanza.name ~= "iq" and cached_stanza:get_child("delay", xmlns_delay) == nil then
  224             cached_stanza = cached_stanza:tag("delay", {
  225                 xmlns = xmlns_delay,
  226                 from = jid.bare(session.full_jid or session.host),
  227                 stamp = datetime.datetime()
  228             });
  229         end
  230 
  231         queue[#queue+1] = cached_stanza;
  232         if session.hibernating then
  233             session.log("debug", "hibernating since %s, stanza queued", datetime.datetime(session.hibernating));
  234             module:fire_event("smacks-hibernation-stanza-queued", {origin = session, queue = queue, stanza = cached_stanza});
  235             return nil;
  236         end
  237         request_ack_if_needed(session, false, "outgoing_stanza_filter", stanza);
  238     end
  239     return stanza;
  240 end
  241 
  242 local function count_incoming_stanzas(stanza, session)
  243     if not stanza.attr.xmlns then
  244         session.handled_stanza_count = session.handled_stanza_count + 1;
  245         session.log("debug", "Handled %d incoming stanzas", session.handled_stanza_count);
  246     end
  247     return stanza;
  248 end
  249 
  250 local function wrap_session_out(session, resume)
  251     if not resume then
  252         session.outgoing_stanza_queue = {};
  253         session.last_acknowledged_stanza = 0;
  254     end
  255 
  256     add_filter(session, "stanzas/out", outgoing_stanza_filter, -999);
  257 
  258     local session_close = session.close;
  259     function session.close(...)
  260         if session.resumption_token then
  261             session_registry.set(session.username, session.resumption_token, nil);
  262             old_session_registry.set(session.username, session.resumption_token, nil);
  263             session.resumption_token = nil;
  264         end
  265         -- send out last ack as per revision 1.5.2 of XEP-0198
  266         if session.smacks and session.conn then
  267             (session.sends2s or session.send)(st.stanza("a", { xmlns = session.smacks, h = string.format("%d", session.handled_stanza_count) }));
  268         end
  269         return session_close(...);
  270     end
  271     return session;
  272 end
  273 
  274 local function wrap_session_in(session, resume)
  275     if not resume then
  276         session.handled_stanza_count = 0;
  277     end
  278     add_filter(session, "stanzas/in", count_incoming_stanzas, 999);
  279 
  280     return session;
  281 end
  282 
  283 local function wrap_session(session, resume)
  284     wrap_session_out(session, resume);
  285     wrap_session_in(session, resume);
  286     return session;
  287 end
  288 
  289 function handle_enable(session, stanza, xmlns_sm)
  290     local ok, err, err_text = can_do_smacks(session);
  291     if not ok then
  292         session.log("warn", "Failed to enable smacks: %s", err_text); -- TODO: XEP doesn't say we can send error text, should it?
  293         (session.sends2s or session.send)(st.stanza("failed", { xmlns = xmlns_sm }):tag(err, { xmlns = xmlns_errors}));
  294         return true;
  295     end
  296 
  297     module:log("debug", "Enabling stream management");
  298     session.smacks = xmlns_sm;
  299 
  300     wrap_session(session, false);
  301 
  302     local resume_token;
  303     local resume = stanza.attr.resume;
  304     if resume == "true" or resume == "1" then
  305         resume_token = uuid_generate();
  306         session_registry.set(session.username, resume_token, session);
  307         session.resumption_token = resume_token;
  308     end
  309     (session.sends2s or session.send)(st.stanza("enabled", { xmlns = xmlns_sm, id = resume_token, resume = resume, max = tostring(resume_timeout) }));
  310     return true;
  311 end
  312 module:hook_stanza(xmlns_sm2, "enable", function (session, stanza) return handle_enable(session, stanza, xmlns_sm2); end, 100);
  313 module:hook_stanza(xmlns_sm3, "enable", function (session, stanza) return handle_enable(session, stanza, xmlns_sm3); end, 100);
  314 
  315 module:hook_stanza("http://etherx.jabber.org/streams", "features",
  316         function (session, stanza)
  317             stoppable_timer(1e-6, function ()
  318                 if can_do_smacks(session) then
  319                     if stanza:get_child("sm", xmlns_sm3) then
  320                         session.sends2s(st.stanza("enable", sm3_attr));
  321                         session.smacks = xmlns_sm3;
  322                     elseif stanza:get_child("sm", xmlns_sm2) then
  323                         session.sends2s(st.stanza("enable", sm2_attr));
  324                         session.smacks = xmlns_sm2;
  325                     else
  326                         return;
  327                     end
  328                     wrap_session_out(session, false);
  329                 end
  330             end);
  331         end);
  332 
  333 function handle_enabled(session, stanza, xmlns_sm)
  334     module:log("debug", "Enabling stream management");
  335     session.smacks = xmlns_sm;
  336 
  337     wrap_session_in(session, false);
  338 
  339     -- FIXME Resume?
  340 
  341     return true;
  342 end
  343 module:hook_stanza(xmlns_sm2, "enabled", function (session, stanza) return handle_enabled(session, stanza, xmlns_sm2); end, 100);
  344 module:hook_stanza(xmlns_sm3, "enabled", function (session, stanza) return handle_enabled(session, stanza, xmlns_sm3); end, 100);
  345 
  346 function handle_r(origin, stanza, xmlns_sm)
  347     if not origin.smacks then
  348         module:log("debug", "Received ack request from non-smack-enabled session");
  349         return;
  350     end
  351     module:log("debug", "Received ack request, acking for %d", origin.handled_stanza_count);
  352     -- Reply with <a>
  353     (origin.sends2s or origin.send)(st.stanza("a", { xmlns = xmlns_sm, h = string.format("%d", origin.handled_stanza_count) }));
  354     -- piggyback our own ack request if needed (see request_ack_if_needed() for explanation of last_requested_h)
  355     local expected_h = origin.last_acknowledged_stanza + #origin.outgoing_stanza_queue;
  356     if #origin.outgoing_stanza_queue > 0 and expected_h ~= origin.last_requested_h then
  357         request_ack_if_needed(origin, true, "piggybacked by handle_r", nil);
  358     end
  359     return true;
  360 end
  361 module:hook_stanza(xmlns_sm2, "r", function (origin, stanza) return handle_r(origin, stanza, xmlns_sm2); end);
  362 module:hook_stanza(xmlns_sm3, "r", function (origin, stanza) return handle_r(origin, stanza, xmlns_sm3); end);
  363 
  364 function handle_a(origin, stanza)
  365     if not origin.smacks then return; end
  366     origin.awaiting_ack = nil;
  367     if origin.awaiting_ack_timer then
  368         origin.awaiting_ack_timer:stop();
  369     end
  370     if origin.delayed_ack_timer then
  371         origin.delayed_ack_timer:stop();
  372         origin.delayed_ack_timer = nil;
  373     end
  374     -- Remove handled stanzas from outgoing_stanza_queue
  375     -- origin.log("debug", "ACK: h=%s, last=%s", stanza.attr.h or "", origin.last_acknowledged_stanza or "");
  376     local h = tonumber(stanza.attr.h);
  377     if not h then
  378         origin:close{ condition = "invalid-xml"; text = "Missing or invalid 'h' attribute"; };
  379         return;
  380     end
  381     local handled_stanza_count = h-origin.last_acknowledged_stanza;
  382     local queue = origin.outgoing_stanza_queue;
  383     if handled_stanza_count > #queue then
  384         origin.log("warn", "The client says it handled %d new stanzas, but we only sent %d :)",
  385             handled_stanza_count, #queue);
  386         origin.log("debug", "Client h: %d, our h: %d", tonumber(stanza.attr.h), origin.last_acknowledged_stanza);
  387         for i=1,#queue do
  388             origin.log("debug", "Q item %d: %s", i, tostring(queue[i]));
  389         end
  390     end
  391 
  392     for i=1,math_min(handled_stanza_count,#queue) do
  393         local handled_stanza = t_remove(origin.outgoing_stanza_queue, 1);
  394         module:fire_event("delivery/success", { session = origin, stanza = handled_stanza });
  395     end
  396 
  397     origin.log("debug", "#queue = %d", #queue);
  398     origin.last_acknowledged_stanza = origin.last_acknowledged_stanza + handled_stanza_count;
  399     request_ack_if_needed(origin, false, "handle_a", nil)
  400     return true;
  401 end
  402 module:hook_stanza(xmlns_sm2, "a", handle_a);
  403 module:hook_stanza(xmlns_sm3, "a", handle_a);
  404 
  405 --TODO: Optimise... incoming stanzas should be handled by a per-session
  406 -- function that has a counter as an upvalue (no table indexing for increments,
  407 -- and won't slow non-198 sessions). We can also then remove the .handled flag
  408 -- on stanzas
  409 
  410 local function handle_unacked_stanzas(session)
  411     local queue = session.outgoing_stanza_queue;
  412     local error_attr = { type = "cancel" };
  413     if #queue > 0 then
  414         session.outgoing_stanza_queue = {};
  415         for i=1,#queue do
  416             if not module:fire_event("delivery/failure", { session = session, stanza = queue[i] }) then
  417                 if queue[i].attr.type ~= "error" then
  418                     local reply = st.reply(queue[i]);
  419                     if reply.attr.to ~= session.full_jid then
  420                         reply.attr.type = "error";
  421                         reply:tag("error", error_attr)
  422                             :tag("recipient-unavailable", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"});
  423                         core_process_stanza(session, reply);
  424                     end
  425                 end
  426             end
  427         end
  428     end
  429 end
  430 
  431 -- don't send delivery errors for messages which will be delivered by mam later on
  432 -- check if stanza was archived --> this will allow us to send back errors for stanzas not archived
  433 -- because the user configured the server to do so ("no-archive"-setting for one special contact for example)
  434 local function get_stanza_id(stanza, by_jid)
  435     for tag in stanza:childtags("stanza-id", "urn:xmpp:sid:0") do
  436         if tag.attr.by == by_jid then
  437             return tag.attr.id;
  438         end
  439     end
  440     return nil;
  441 end
  442 module:hook("delivery/failure", function(event)
  443     local session, stanza = event.session, event.stanza;
  444     -- Only deal with authenticated (c2s) sessions
  445     if session.username then
  446         if stanza.name == "message" and stanza.attr.xmlns == nil and
  447                 ( stanza.attr.type == "chat" or ( stanza.attr.type or "normal" ) == "normal" ) then
  448             -- don't store messages in offline store if they are mam results
  449             local mam_result = stanza:get_child("result", xmlns_mam2);
  450             if mam_result ~= nil then
  451                 return true;        -- stanza already "handled", don't send an error and don't add it to offline storage
  452             end
  453             -- do nothing here for normal messages and don't send out "message delivery errors",
  454             -- because messages are already in MAM at this point (no need to frighten users)
  455             local stanza_id = get_stanza_id(stanza, jid.bare(session.full_jid));
  456             if session.mam_requested and stanza_id ~= nil then
  457                 session.log("debug", "mod_smacks delivery/failure returning true for mam-handled stanza: mam-archive-id=%s", tostring(stanza_id));
  458                 return true;        -- stanza handled, don't send an error
  459             end
  460             -- store message in offline store, if this client does not use mam *and* was the last client online
  461             local sessions = prosody.hosts[module.host].sessions[session.username] and
  462                     prosody.hosts[module.host].sessions[session.username].sessions or nil;
  463             if sessions and next(sessions) == session.resource and next(sessions, session.resource) == nil then
  464                 local ok = module:fire_event("message/offline/handle", { origin = session, stanza = stanza } );
  465                 session.log("debug", "mod_smacks delivery/failuere returning %s for offline-handled stanza", tostring(ok));
  466                 return ok;          -- if stanza was handled, don't send an error
  467             end
  468         end
  469     end
  470 end);
  471 
  472 module:hook("pre-resource-unbind", function (event)
  473     local session, err = event.session, event.error;
  474     if session.smacks then
  475         if not session.resumption_token then
  476             local queue = session.outgoing_stanza_queue;
  477             if #queue > 0 then
  478                 session.log("debug", "Destroying session with %d unacked stanzas", #queue);
  479                 handle_unacked_stanzas(session);
  480             end
  481         else
  482             session.log("debug", "mod_smacks hibernating session for up to %d seconds", resume_timeout);
  483             local hibernate_time = os_time(); -- Track the time we went into hibernation
  484             session.hibernating = hibernate_time;
  485             local resumption_token = session.resumption_token;
  486             module:fire_event("smacks-hibernation-start", {origin = session, queue = session.outgoing_stanza_queue});
  487             timer.add_task(resume_timeout, function ()
  488                 session.log("debug", "mod_smacks hibernation timeout reached...");
  489                 -- We need to check the current resumption token for this resource
  490                 -- matches the smacks session this timer is for in case it changed
  491                 -- (for example, the client may have bound a new resource and
  492                 -- started a new smacks session, or not be using smacks)
  493                 local curr_session = full_sessions[session.full_jid];
  494                 if session.destroyed then
  495                     session.log("debug", "The session has already been destroyed");
  496                 elseif curr_session and curr_session.resumption_token == resumption_token
  497                 -- Check the hibernate time still matches what we think it is,
  498                 -- otherwise the session resumed and re-hibernated.
  499                 and session.hibernating == hibernate_time then
  500                     -- wait longer if the timeout isn't reached because push was enabled for this session
  501                     -- session.first_hibernated_push is the starting point for hibernation timeouts of those push enabled clients
  502                     -- wait for an additional resume_timeout seconds if no push occured since hibernation at all
  503                     local current_time = os_time();
  504                     local timeout_start = math_max(session.hibernating, session.first_hibernated_push or session.hibernating);
  505                     if session.push_identifier ~= nil and not session.first_hibernated_push then
  506                         session.log("debug", "No push happened since hibernation started, hibernating session for up to %d extra seconds", resume_timeout);
  507                         return resume_timeout;
  508                     end
  509                     if session.push_identifier ~= nil and current_time-timeout_start < resume_timeout then
  510                         session.log("debug", "A push happened since hibernation started, hibernating session for up to %d extra seconds", resume_timeout-(current_time-timeout_start));
  511                         return resume_timeout-(current_time-timeout_start);     -- time left to wait
  512                     end
  513                     session.log("debug", "Destroying session for hibernating too long");
  514                     session_registry.set(session.username, session.resumption_token, nil);
  515                     -- save only actual h value and username/host (for security)
  516                     old_session_registry.set(session.username, session.resumption_token, {
  517                         h = session.handled_stanza_count,
  518                         username = session.username,
  519                         host = session.host
  520                     });
  521                     session.resumption_token = nil;
  522                     sessionmanager.destroy_session(session);
  523                 else
  524                     session.log("debug", "Session resumed before hibernation timeout, all is well")
  525                 end
  526             end);
  527             return true; -- Postpone destruction for now
  528         end
  529     end
  530 end);
  531 
  532 local function handle_s2s_destroyed(event)
  533     local session = event.session;
  534     local queue = session.outgoing_stanza_queue;
  535     if queue and #queue > 0 then
  536         session.log("warn", "Destroying session with %d unacked stanzas", #queue);
  537         if s2s_resend then
  538             for i = 1, #queue do
  539                 module:send(queue[i]);
  540             end
  541             session.outgoing_stanza_queue = nil;
  542         else
  543             handle_unacked_stanzas(session);
  544         end
  545     end
  546 end
  547 
  548 module:hook("s2sout-destroyed", handle_s2s_destroyed);
  549 module:hook("s2sin-destroyed", handle_s2s_destroyed);
  550 
  551 local function get_session_id(session)
  552     return session.id or (tostring(session):match("[a-f0-9]+$"));
  553 end
  554 
  555 function handle_resume(session, stanza, xmlns_sm)
  556     if session.full_jid then
  557         session.log("warn", "Tried to resume after resource binding");
  558         session.send(st.stanza("failed", { xmlns = xmlns_sm })
  559             :tag("unexpected-request", { xmlns = xmlns_errors })
  560         );
  561         return true;
  562     end
  563 
  564     local id = stanza.attr.previd;
  565     local original_session = session_registry.get(session.username, id);
  566     if not original_session then
  567         session.log("debug", "Tried to resume non-existent session with id %s", id);
  568         local old_session = old_session_registry.get(session.username, id);
  569         if old_session and session.username == old_session.username
  570         and session.host == old_session.host
  571         and old_session.h then
  572             session.send(st.stanza("failed", { xmlns = xmlns_sm, h = string.format("%d", old_session.h) })
  573                 :tag("item-not-found", { xmlns = xmlns_errors })
  574             );
  575         else
  576             session.send(st.stanza("failed", { xmlns = xmlns_sm })
  577                 :tag("item-not-found", { xmlns = xmlns_errors })
  578             );
  579         end;
  580     elseif session.username == original_session.username
  581     and session.host == original_session.host then
  582         session.log("debug", "mod_smacks resuming existing session %s...", get_session_id(original_session));
  583         original_session.log("debug", "mod_smacks session resumed from %s...", get_session_id(session));
  584         -- TODO: All this should move to sessionmanager (e.g. session:replace(new_session))
  585         if original_session.conn then
  586             original_session.log("debug", "mod_smacks closing an old connection for this session");
  587             local conn = original_session.conn;
  588             c2s_sessions[conn] = nil;
  589             conn:close();
  590         end
  591         local migrated_session_log = session.log;
  592         original_session.ip = session.ip;
  593         original_session.conn = session.conn;
  594         original_session.send = session.send;
  595         original_session.close = session.close;
  596         original_session.filter = session.filter;
  597         original_session.filter.session = original_session;
  598         original_session.filters = session.filters;
  599         original_session.stream = session.stream;
  600         original_session.secure = session.secure;
  601         original_session.hibernating = nil;
  602         session.log = original_session.log;
  603         session.type = original_session.type;
  604         wrap_session(original_session, true);
  605         -- Inform xmppstream of the new session (passed to its callbacks)
  606         original_session.stream:set_session(original_session);
  607         -- Similar for connlisteners
  608         c2s_sessions[session.conn] = original_session;
  609 
  610         original_session.send(st.stanza("resumed", { xmlns = xmlns_sm,
  611             h = string.format("%d", original_session.handled_stanza_count), previd = id }));
  612 
  613         -- Fake an <a> with the h of the <resume/> from the client
  614         original_session:dispatch_stanza(st.stanza("a", { xmlns = xmlns_sm,
  615             h = stanza.attr.h }));
  616 
  617         -- Ok, we need to re-send any stanzas that the client didn't see
  618         -- ...they are what is now left in the outgoing stanza queue
  619         -- We have to use the send of "session" because we don't want to add our resent stanzas
  620         -- to the outgoing queue again
  621         local queue = original_session.outgoing_stanza_queue;
  622         session.log("debug", "resending all unacked stanzas that are still queued after resume, #queue = %d", #queue);
  623         for i=1,#queue do
  624             session.send(queue[i]);
  625         end
  626         session.log("debug", "all stanzas resent, now disabling send() in this migrated session, #queue = %d", #queue);
  627         function session.send(stanza)
  628             migrated_session_log("error", "Tried to send stanza on old session migrated by smacks resume (maybe there is a bug?): %s", tostring(stanza));
  629             return false;
  630         end
  631         module:fire_event("smacks-hibernation-end", {origin = session, resumed = original_session, queue = queue});
  632         request_ack_if_needed(original_session, true, "handle_resume", nil);
  633     else
  634         module:log("warn", "Client %s@%s[%s] tried to resume stream for %s@%s[%s]",
  635             session.username or "?", session.host or "?", session.type,
  636             original_session.username or "?", original_session.host or "?", original_session.type);
  637         session.send(st.stanza("failed", { xmlns = xmlns_sm })
  638             :tag("not-authorized", { xmlns = xmlns_errors }));
  639     end
  640     return true;
  641 end
  642 module:hook_stanza(xmlns_sm2, "resume", function (session, stanza) return handle_resume(session, stanza, xmlns_sm2); end);
  643 module:hook_stanza(xmlns_sm3, "resume", function (session, stanza) return handle_resume(session, stanza, xmlns_sm3); end);
  644 
  645 module:hook("csi-client-active", function (event)
  646     if event.origin.smacks then
  647         request_ack_if_needed(event.origin, true, "csi-active", nil);
  648     end
  649 end);
  650 
  651 module:hook("csi-flushing", function (event)
  652     if event.session.smacks then
  653         request_ack_if_needed(event.session, true, "csi-active", nil);
  654     end
  655 end);
  656 
  657 local function handle_read_timeout(event)
  658     local session = event.session;
  659     if session.smacks then
  660         if session.awaiting_ack then
  661             if session.awaiting_ack_timer then
  662                 session.awaiting_ack_timer:stop();
  663             end
  664             if session.delayed_ack_timer then
  665                 session.delayed_ack_timer:stop();
  666                 session.delayed_ack_timer = nil;
  667             end
  668             return false; -- Kick the session
  669         end
  670         session.log("debug", "Sending <r> (read timeout)");
  671         (session.sends2s or session.send)(st.stanza("r", { xmlns = session.smacks }));
  672         session.awaiting_ack = true;
  673         if not session.delayed_ack_timer then
  674             session.delayed_ack_timer = stoppable_timer(delayed_ack_timeout, function()
  675                 delayed_ack_function(session, nil);
  676             end);
  677         end
  678         return true;
  679     end
  680 end
  681 
  682 module:hook("s2s-read-timeout", handle_read_timeout);
  683 module:hook("c2s-read-timeout", handle_read_timeout);