-- XEP-0215 implementation for time-limited turn credentials

-- Copyright (C) 2012-2013 Philipp Hancke

-- This file is MIT/X11 licensed. 

local st = require "util.stanza";

local hmac_sha1 = require "util.hmac".sha1;

local base64 = require "util.encodings".base64;

local os_time = os.time;

local secret = module:get_option("turncredentials_secret") or false;

local host = module:get_option("turncredentials_host") or false -- use ip addresses here to avoid further dns lookup latency

local port = module:get_option("turncredentials_port") or 3478

if not (secret and host) then

    module:log("error", "turncredentials not configured");

    return;

end

module:hook("iq/host/urn:xmpp:extdisco:1:services", function(event)

    local origin, stanza = event.origin, event.stanza;

    if stanza.attr.type ~= "get" or stanza.tags[1].name ~= "services" or origin.type ~= "c2s" then

        return;

    end

    local now = os_time();

    local userpart = tostring(now);

    local nonce = base64.encode(hmac_sha1(secret, tostring(userpart), false));

    origin.send(st.reply(stanza):tag("services", {xmlns = "urn:xmpp:extdisco:1"})

        :tag("service", { type = "stun", host = host, port = port }):up()

        :tag("service", { type = "turn", host = host, port = port, username = userpart, password = nonce }):up()

    );

    return true;

end);