-- 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.hashes".hmac_sha1;

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

local os_time = os.time;

local datetime = require "util.datetime".datetime;

local secret = module:get_option_string("turncredentials_secret");

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

local port = module:get_option_number("turncredentials_port", 3478);

local ttl = module:get_option_number("turncredentials_ttl", 86400);

if not (secret and host) then

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

    return;

end

module:add_feature("urn:xmpp:extdisco:1");

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

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

    if origin.type ~= "c2s" then

        return;

    end

    local now = os_time() + ttl;

    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 = ("%d"):format(port) }):up()

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

    );

    return true;

end);

module:add_feature("urn:xmpp:extdisco:2");

module:hook("iq-get/host/urn:xmpp:extdisco:2:services", function(event)

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

    if origin.type ~= "c2s" then

        return;

    end

    local now = os_time() + ttl;

    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:2"})

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

        :tag("service", { type = "turn", host = host, port = ("%d"):format(port), username = userpart, password = nonce, expires = datetime(ttl), restricted = "1"  }):up()

    );

    return true;

end);