mod_pubsub_serverinfo: implemented all basic features
This commit replaces the earlier proof-of-concept to a solution that:
- reports on remotely-connected domains
- uses disco/info to detect if those domains opt-in
- publishes domain names for remote domains that do so
- caches the disco/info response
--- a/mod_pubsub_serverinfo/README.markdown Wed Jan 03 07:53:55 2024 +0100
+++ b/mod_pubsub_serverinfo/README.markdown Wed Jan 03 23:05:14 2024 +0100
@@ -5,4 +5,39 @@
Exposes server information over Pub/Sub per ProtoXEP: PubSub Server Information.
-This initial version only announces support (used to 'opt-in', per the XEP). It does not publish any data. This is intended to be a future addition to this mod.
+This version, announces support (used to 'opt-in', per the XEP) and publishes the name of the local domain via a Pub/Sub node. The published data
+will contain an unnamed 'remote-domain' element for each inbound or outgoing s2s connection.
+
+Features yet to be implemented:
+- For 'remote-domain' elements, add domain name _only if_ through service discovery that domain advertises the 'urn:xmpp:serverinfo:0' feature.
+
+Installation
+============
+
+Enable this module in the global or a virtual host.
+
+The default configuration requires the existence of a Pub/Sub component that uses the 'pubsub' subdomain of the host in which the module is enabled:
+
+ Component "pubsub.example.org" "pubsub"
+
+The module will create a node and publish data, using a JID that matches the XMPP domain name of the host. Ensure that this actor is an admin of the
+Pub/Sub service:
+
+ admins = { "example.org" }
+
+Configuration
+=============
+
+The Pub/Sub service on which data is published, by default, is a component addressed as the `pubsub` subdomain of the domain of the virtual host that
+the module is loaded under. To change this, apply this configuration setting:
+
+ pubsub_serverinfo_service = "anotherpubsub.example.org"
+
+The Pub/Sub node on which data is published is, by default, a leaf-node named `serverinfo`. To change this, apply this configuration setting:
+
+ pubsub_serverinfo_node = "foobar"
+
+To prevent a surplus of event notifications, this module will only publish new data after a certain period of time has expired. The default duration
+is 300 seconds (5 minutes). To change this simply put in the config:
+
+ pubsub_serverinfo_publication_interval = 180 -- or any other number of seconds
--- a/mod_pubsub_serverinfo/mod_pubsub_serverinfo.lua Wed Jan 03 07:53:55 2024 +0100
+++ b/mod_pubsub_serverinfo/mod_pubsub_serverinfo.lua Wed Jan 03 23:05:14 2024 +0100
@@ -1,1 +1,168 @@
-module:add_feature("urn:xmpp:serverinfo:0");
+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 opt_in_reports
+
+function module.load()
+ -- Will error out with a 'conflict' if the node already exists. TODO: create the node only when it's missing.
+ create_node():next()
+
+ 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
+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")
+ return module:send_iq(request);
+end
+
+-- Returns a promise
+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 });
+
+ return module:send_iq(request);
+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()
+
+ 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() + 3600;
+ }
+ return; -- prevent 'false' to be cached, down below.
+ end
+ end
+ end
+ end
+ opt_in_cache[remoteDomain] = {
+ opt_in = false;
+ expires = os.time() + 3600;
+ }
+ end,
+ function(response)
+ opt_in_cache[remoteDomain] = {
+ opt_in = false;
+ expires = os.time() + 3600;
+ }
+ end
+ );
+
+ -- return 'false' for now. Better luck next time...
+ return false;
+
+end