SleepProxyServer

mDNS (Bonjour) Sleep Proxy Server implementation for Python

Provides the Wake on Demand service, similarly to Apple TV and Airport Express devices

Status

SPS has been tested against SleepProxyClient, OSX 10.9's mDNSResponder, and OSX 10.10's discoveryd.
See Debugging instructions below to test other implementations.
Selective-port waking is not implemented, any TCP request to a sleep client will result in a wakeup attempt.

A port to C(++) or Go would be welcome for resource limited ARM devices.

Internals

The included server daemon, scripts/sleeproxyd, binds port 5353 and loops up some greenlets:

• dnsserve.py: Handle DNSUPDATE registrations sent to UDP:5353 from sleep proxy clients (aka. "sleepers") that are powering down
• arp.py: Spoof ARP replies for requests from wakers for the sleepers' IP addr. Also monitors sleepers own gratuitous ARPs after wakeup, which deregisters them.
• mdns.py: Mirrors the mDNS service advertisements of sleepers with Avahi so that their services can still be browsed by wakers on the local network.
• tcp.py: Listen for wakers' TCP requests to sleepers. On receipt, will attempt to wake the sleeper with a WOL "magic packet".

Installation

Being based on ZeroConf, SPS requires almost no configuration.
Just run it and clients will see its mDNS advertisement and register to it within their regular polling intervals and/or just before sleeping.
sudo pmset networkoversleep 1 may be necessary to ensure OSX clients will publish services at-all-costs.
You must ensure both SPS server and client use the same network-segment and IP subnet and that IP Multicast traffic between them is not blocked.

gevent 1.0 is required for its co-operative threading feature; its packaged in Debian jessie.
Because of this, SPS can't be run under python3 (FIXME: replace gevent with asyncio)

• Debian 8.0+ (jessie) & Ubuntu 14.04+ (Trusty Tahr)

apt-get install python-scapy python-netifaces python-dbus python-gevent python-pip python-setuptools avahi-daemon git
pip install git+https://github.com/kfix/SleepProxyServer.git
nohup sleepproxyd >/dev/null 2>&1 &
#^put that in rc.local or an initscript or systemd-unit

• OpenWRT
• oWRT asyncIO opkg install python3-asyncio

Development & Debugging

• run a canned client-less server and test a with a mock registration

scripts/test

• debug segfaults in cpython or gevent on Debian/Ubuntu

apt-get install gdb python2.7-dbg libc6-dbg python-dbus-dbg python-netifaces-dbg
cd SleepProxyServer/
python setup.py develop --exclude-scripts
gdb -ex r --args python2.7 scripts/sleepproxyd

• play with scapy filters

scapy
sniff(tcpwatch, prn=lambda x: x.display(), filter='tcp[tcpflags] & tcp-syn != 0 and tcp[tcpflags] & tcp-ack = 0 and dst host 10.1.0.15', iface='eth0')
sniff(prn=lambda x: x.display(), filter='arp host 10.1.0.15', iface='eth0')

• Watch OSX syslog for alll SPS-related actions (sudo-root required) Press Ctrl-T to sleep-wake-cycle your Mac, generating a SPS registration

scripts/sleepproxy_debug_osx

• advertise services to SPS from your (Obj)C.app by unsetting service flag kDNSServiceFlagsWakeOnlyService

Further Reading

• mDNS rfc
  • draft #8 is last version to describe Sleep Proxy services @ sec 17.: http://tools.ietf.org/id/draft-cheshire-dnsext-multicastdns-08.txt
• ZeroConf rfc
• http://datatracker.ietf.org/wg/dnssd/charter/
  • changes to mDNS/ZC for larger networks are under development: https://datatracker.ietf.org/doc/draft-ietf-dnssd-hybrid/
  • https://datatracker.ietf.org/doc/rfc8222/