+local function calculate_hash(disco_info)
+ local identities, features, extensions = {}, {}, {};
+ for _, tag in pairs(disco_info) do
+ if tag.name == "identity" then
+ table.insert(identities, (tag.attr.category or "").."\0"..(tag.attr.type or "").."\0"..(tag.attr["xml:lang"] or "").."\0"..(tag.attr.name or ""));
+ elseif tag.name == "feature" then
+ table.insert(features, tag.attr.var or "");
+ elseif tag.name == "x" and tag.attr.xmlns == "jabber:x:data" then
+ local form = {};
+ local FORM_TYPE;
+ for _, field in pairs(tag.tags) do
+ if field.name == "field" and field.attr.var then
+ local values = {};
+ for _, val in pairs(field.tags) do
+ val = #val.tags == 0 and table.concat(val); -- FIXME use get_text?
+ if val then table.insert(values, val); end
+ end
+ table.sort(values);
+ if field.attr.var == "FORM_TYPE" then
+ FORM_TYPE = values[1];
+ elseif #values > 0 then
+ table.insert(form, field.attr.var.."\0"..table.concat(values, "<"));
+ else
+ table.insert(form, field.attr.var);
+ end
+ end
+ end
+ table.sort(form);
+ form = table.concat(form, "<");
+ if FORM_TYPE then form = FORM_TYPE.."\0"..form; end
+ table.insert(extensions, form);
+ end
+ end
+ table.sort(identities);
+ table.sort(features);
+ table.sort(extensions);
+ if #identities > 0 then identities = table.concat(identities, "<"):gsub("%z", "/").."<"; else identities = ""; end
+ if #features > 0 then features = table.concat(features, "<").."<"; else features = ""; end
+ if #extensions > 0 then extensions = table.concat(extensions, "<"):gsub("%z", "<").."<"; else extensions = ""; end
+ local S = identities..features..extensions;
+ local ver = base64(sha1(S));
+ return ver, S;
+end
+
+module:hook("iq/bare/disco", function(event)
+ local session, stanza = event.origin, event.stanza;
+ if stanza.attr.type == "result" then
+ local disco = stanza.tags[1];
+ if disco and disco.name == "query" and disco.attr.xmlns == "http://jabber.org/protocol/disco#info" then
+ -- Process disco response
+ local user = stanza.attr.to or (session.username..'@'..session.host);
+ local contact = stanza.attr.from;
+ local current = recipients[user] and recipients[user][contact];
+ if type(current) ~= "string" then return; end -- check if waiting for recipient's response
+ local ver = current;
+ if not string.find(current, "#") then
+ ver = calculate_hash(disco.tags); -- calculate hash
+ end
+ local notify = {};
+ for _, feature in pairs(disco.tags) do
+ if feature.name == "feature" and feature.attr.var then
+ local nfeature = feature.attr.var:match("^(.*)%+notify$");
+ if nfeature then notify[nfeature] = true; end
+ end
+ end
+ hash_map[ver] = notify; -- update hash map
+ recipients[user][contact] = notify; -- set recipient's data to calculated data
+ -- send messages to recipient
+ publish_all(user, contact, session);
+ end
+ end
+end);