--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_muc_occupant_id/mod_muc_occupant_id.lua Sun Jul 14 18:45:10 2019 +0200
@@ -0,0 +1,59 @@
+
+-- Implementation of https://dino.im/xeps/occupant-id.html
+-- XEP-XXXX: Anonymous unique occupant identifiers for MUCs
+
+local uuid = require "util.uuid";
+local hmac_sha256 = require "util.hashes".hmac_sha256;
+local b64encode = require "util.encodings".base64.encode;
+
+local xmlns_occupant_id = "urn:xmpp:occupant-id:0";
+
+local function edit_occupant(event)
+ local occupant, room = event.occupant, event.room;
+ local bare = occupant.bare_jid;
+
+ -- TODO: Move the salt on the MUC component. Setting the salt on the room
+ -- can be problematic when the room is destroyed. Next time it's recreated
+ -- the salt will be different and so will be the unique_id. Or maybe we want
+ -- this anyway?
+ if room._data.occupant_id_salt == nil then
+ local salt = uuid.generate();
+ room._data.occupant_id_salt = salt;
+ end
+
+ local unique_id = b64encode(hmac_sha256(bare, room._data.occupant_id_salt));
+
+ -- TODO: Store this only once per bare jid and not once per occupant?
+ local stanza = event.stanza;
+ stanza:tag("occupant-id", { xmlns = xmlns_occupant_id })
+ :text(unique_id)
+ :up();
+end
+
+local function handle_stanza(event)
+ local stanza, occupant = event.stanza, event.occupant;
+
+ if stanza.name == "presence" and stanza.attr.type == "unavailable" then -- not required here
+ return;
+ end
+
+ -- strip any existing <occupant-id/> tags to avoid forgery
+ stanza:remove_children("occupant-id", xmlns_occupant_id);
+
+ if not occupant then return; end
+
+ local unique_id = occupant.sessions[stanza.attr.from]
+ :get_child("occupant-id", xmlns_occupant_id)
+ :get_text();
+ stanza:tag("occupant-id", { xmlns = xmlns_occupant_id })
+ :text(unique_id)
+ :up();
+end
+
+module:add_feature(xmlns_occupant_id);
+module:hook("muc-disco#info", function (event)
+ event.reply:tag("feature", { var = xmlns_occupant_id }):up();
+end);
+
+module:hook("muc-occupant-pre-join", edit_occupant);
+module:hook("muc-occupant-groupchat", handle_stanza);