mod_pubsub_serverinfo: Disco/info cache TTL should be configurable
This module caches the disco/info results of remote domains. This commit introduces a new configuration option that allows an admin to configure the cache expiry duration.
local st = require "util.stanza";
local new_id = require"util.id".medium;
local dataform = require "util.dataforms".new;
local local_domain = module:get_host();
local service = module:get_option(module.name .. "_service") or "pubsub." .. local_domain;
local node = module:get_option(module.name .. "_node") or "serverinfo";
local actor = module.host .. "/modules/" .. module.name;
local publication_interval = module:get_option(module.name .. "_publication_interval") or 300;
local cache_ttl = module:get_option(module.name .. "_cache_ttl") or 3600;
local opt_in_reports
function module.load()
discover_node():next(
function(exists)
if not exists then create_node() end
end
):catch(
function(error)
module:log("warn", "Error prevented discovery or creation of pub/sub node at %s: %s", service, error)
end
)
module:add_feature("urn:xmpp:serverinfo:0");
module:add_extension(dataform {
{ name = "FORM_TYPE", type = "hidden", value = "http://jabber.org/network/serverinfo" },
{ name = "serverinfo-pubsub-node", type = "text-single" },
}:form({ ["serverinfo-pubsub-node"] = ("xmpp:%s?;node=%s"):format(service, node) }, "result"));
module:add_timer(10, publish_serverinfo);
end
function module.unload()
-- This removes all subscribers, which may or may not be desirable, depending on the reason for the unload.
delete_node(); -- Should this block, to delay unload() until the node is deleted?
end
-- Returns a promise of a boolean
function discover_node()
local request = st.iq({ type = "get", to = service, from = actor, id = new_id() })
:tag("query", { xmlns = "http://jabber.org/protocol/disco#items" })
module:log("debug", "Sending request to discover existence of pub/sub node '%s' at %s", node, service)
return module:send_iq(request):next(
function(response)
if response.stanza == nil or response.stanza.attr.type ~= "result" then
module:log("warn", "Unexpected response to service discovery items request at %s: %s", service, response.stanza)
return false
end
local query = response.stanza:get_child("query", "http://jabber.org/protocol/disco#items")
if query ~= nil then
for item in query:childtags("item") do
if item.attr.jid == service and item.attr.node == node then
module:log("debug", "pub/sub node '%s' at %s does exists.", node, service)
return true
end
end
end
module:log("debug", "pub/sub node '%s' at %s does not exist.", node, service)
return false;
end
);
end
-- Returns a promise of a boolean
function create_node()
local request = st.iq({ type = "set", to = service, from = actor, id = new_id() })
:tag("pubsub", { xmlns = "http://jabber.org/protocol/pubsub" })
:tag("create", { node = node }):up()
:tag("configure")
:tag("x", { xmlns = "jabber:x:data", type = "submit" })
:tag("field", { var = "FORM_TYPE", type = "hidden"})
:text_tag("value", "http://jabber.org/protocol/pubsub#node_config")
:up()
:tag("field", { var = "pubsub#max_items" })
:text_tag("value", "1")
:up()
:tag("field", { var = "pubsub#persist_items" })
:text_tag("value", "0")
module:log("debug", "Sending request to create pub/sub node '%s' at %s", node, service)
return module:send_iq(request):next(
function(response)
if response.stanza == nil or response.stanza.attr.type ~= "result" then
module:log("warn", "Unexpected response to pub/sub node '%s' creation request at %s: %s", node, service, response.stanza)
return false
else
module:log("debug", "Successfully created pub/sub node '%s' at %s", node, service)
return true
end
end
)
end
-- Returns a promise of a boolean
function delete_node()
local request = st.iq({ type = "set", to = service, from = actor, id = new_id() })
:tag("pubsub", { xmlns = "http://jabber.org/protocol/pubsub" })
:tag("delete", { node = node });
module:log("debug", "Sending request to delete pub/sub node '%s' at %s", node, service)
return module:send_iq(request):next(
function(response)
if response.stanza == nil or response.stanza.attr.type ~= "result" then
module:log("warn", "Unexpected response to pub/sub node '%s' deletion request at %s: %s", node, service, response.stanza)
return false
else
module:log("debug", "Successfully deleted pub/sub node '%s' at %s", node, service)
return true
end
end
)
end
function publish_serverinfo()
-- Iterate over s2s sessions, adding them to a multimap, where the key is the local domain name,
-- mapped to a collection of remote domain names. De-duplicate all remote domain names by using
-- them as an index in a table.
local domains_by_host = {}
for session, _ in pairs(prosody.incoming_s2s) do
if session ~= nil and session.from_host ~= nil and local_domain == session.to_host then
local sessions = domains_by_host[session.to_host]
if sessions == nil then sessions = {} end; -- instantiate a new entry if none existed
sessions[session.from_host] = true
domains_by_host[session.to_host] = sessions
end
end
-- At an earlier stage, the code iterated voer all prosody.hosts - but that turned out to be to noisy.
-- for host, data in pairs(prosody.hosts) do
local host = local_domain
local data = prosody.hosts[host]
if data ~= nil then
local sessions = domains_by_host[host]
if sessions == nil then sessions = {} end; -- instantiate a new entry if none existed
if data.s2sout ~= nil then
for _, session in pairs(data.s2sout) do
if session.to_host ~= nil then
sessions[session.to_host] = true
domains_by_host[host] = sessions
end
end
end
end
-- Build the publication stanza.
local request = st.iq({ type = "set", to = service, from = actor, id = new_id() })
:tag("pubsub", { xmlns = "http://jabber.org/protocol/pubsub" })
:tag("publish", { node = node, xmlns = "http://jabber.org/protocol/pubsub" })
:tag("item", { id = "current", xmlns = "http://jabber.org/protocol/pubsub" })
:tag("serverinfo", { xmlns = "urn:xmpp:serverinfo:0" })
request:tag("domain", { name = local_domain })
:tag("federation")
local remotes = domains_by_host[host]
if remotes ~= nil then
for remote, _ in pairs(remotes) do
-- include a domain name for remote domains, but only if they advertise support.
if does_opt_in(remote) then
request:tag("remote-domain", { name = remote }):up()
else
request:tag("remote-domain"):up()
end
end
end
request:up():up()
module:send_iq(request):next(
function(response)
if response.stanza == nil or response.stanza.attr.type ~= "result" then
module:log("warn", "Unexpected response to item publication at pub/sub node '%s' on %s: %s", node, service, response.stanza)
return false
else
module:log("debug", "Successfully published item on pub/sub node '%s' at %s", node, service)
return true
end
end,
function(error)
module:log("warn", "Error prevented publication of item on pub/sub node at %s: %s", service, error)
end
)
return publication_interval;
end
local opt_in_cache = {}
function does_opt_in(remoteDomain)
-- try to read answer from cache.
local cached_value = opt_in_cache[remoteDomain]
if cached_value ~= nil and os.difftime(cached_value.expires, os.time()) > 0 then
return cached_value.opt_in;
end
-- TODO worry about not having multiple requests in flight to the same domain.cached_value
-- Cache could not provide an answer. Perform service discovery.
local discoRequest = st.iq({ type = "get", to = remoteDomain, from = actor, id = new_id() })
:tag("query", { xmlns = "http://jabber.org/protocol/disco#info" })
module:send_iq(discoRequest):next(
function(response)
if response.stanza ~= nil and response.stanza.attr.type == "result" then
local query = response.stanza:get_child("query", "http://jabber.org/protocol/disco#info")
if query ~= nil then
for feature in query:childtags("feature", "http://jabber.org/protocol/disco#info") do
if feature.attr.var == 'urn:xmpp:serverinfo:0' then
opt_in_cache[remoteDomain] = {
opt_in = true;
expires = os.time() + cache_ttl;
}
return; -- prevent 'false' to be cached, down below.
end
end
end
end
opt_in_cache[remoteDomain] = {
opt_in = false;
expires = os.time() + cache_ttl;
}
end,
function(response)
opt_in_cache[remoteDomain] = {
opt_in = false;
expires = os.time() + cache_ttl;
}
end
);
-- return 'false' for now. Better luck next time...
return false;
end