Combine the Prosody extdisco modules.

mod_extdisco.lua

local st = require "util.stanza";
local hmac_sha1 = require "util.hashes".hmac_sha1;
local base64 = require "util.encodings".base64;
local os_time = os.time;

local services = module:get_option("external_services");

local xmlns_extdisco = "urn:xmpp:extdisco:1";


local function gencreds(secret, ttl)
	ttl = ttl or 86400;
	local now = os_time() + ttl;
	local userpart = tostring(now);
	local nonce = base64.encode(hmac_sha1(secret, tostring(userpart), false));
	return {
		username = userpart;
		password = nonce;
		ttl = ttl;
	};
end

module:add_feature(xmlns_extdisco);

module:hook("iq-get/host/"..xmlns_extdisco..":services", function (event)
	local origin, stanza = event.origin, event.stanza;
	local service = stanza:get_child("service", xmlns_extdisco);
	local service_type = service and service.attr.type;
	local reply = st.reply(stanza);
	if origin.type ~= "c2s" then
		return;
	end
	for host, service_info in pairs(services) do
		if not(service_type) or service_info.type == service_type then
			local settings = {
				host = host;
				port = service_info.port;
				transport = service_info.transport;
				type = service_info.type;
			};
			if service_info.gen_shared_secret then
				local creds = gencreds(service_info.gen_shared_secret, service_info.gen_ttl);
				settings.username = creds.username;
				settings.password = creds.password;
			else
				settings.username = service_info.username;
				settings.password = service_info.password;
			end
			reply:tag("service", settings):up();
		end
	end
	origin.send(reply);
	return true;
end);

module:hook("iq-get/host/"..xmlns_extdisco..":credentials", function (event)
	local origin, stanza = event.origin, event.stanza;
	local credentials = stanza:get_child("credentials", xmlns_extdisco);
	local service = credentials and credentials:get_child("service", xmlns_extdisco);
	local host = service and service.attr.host;
	if origin.type ~= "c2s" then
		return;
	end
	if not host then
		origin.send(st.error_reply(stanza, "cancel", "bad-request", "No host specified"));
		return true;
	end
	local service_info = services[host];
	if not service_info then
		origin.send(st.error_reply(stanza, "cancel", "item-not-found", "No such service known"));
		return true;
	end
	local service_creds = { host = host };
	if service_info.gen_shared_secret then
		local creds = gencreds(service_info.gen_shared_secret, service_info.gen_ttl);
		service_creds.username = creds.username;
		service_creds.password = creds.password;
		service_creds.ttl = creds.ttl;
	else
		service_creds.username = service_info.username;
		service_creds.password = service_info.password;
	end
	local reply = st.reply(stanza)
		:tag("credentials")
			:tag("service", service_creds):up();
	origin.send(reply);
	return true;
end);