-- Implementation of https://xmpp.org/extensions/inbox/occupant-id.html
-- XEP-0421: Anonymous unique occupant identifiers for MUCs
module:depends("muc");
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 generate_id(occupant, room)
local bare = occupant.bare_jid;
if room._data.occupant_id_salt == nil then
room._data.occupant_id_salt = uuid.generate();
end
if room._data.occupant_ids == nil then
room._data.occupant_ids = {};
end
if room._data.occupant_ids[bare] == nil then
local unique_id = b64encode(hmac_sha256(bare, room._data.occupant_id_salt));
room._data.occupant_ids[bare] = unique_id;
end
return room._data.occupant_ids[bare];
end
local function update_occupant(event)
local stanza, occupant, room = event.stanza, event.occupant, event.room;
-- strip any existing <occupant-id/> tags to avoid forgery
stanza:remove_children("occupant-id", xmlns_occupant_id);
local unique_id = generate_id(occupant, room);
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);
-- TODO: Handle MUC-PMs
module:hook("muc-broadcast-presence", update_occupant);
module:hook("muc-occupant-pre-join", update_occupant);
module:hook("muc-occupant-groupchat", update_occupant);