import logging
import string
logger = logging.getLogger(__name__)
try:
import dbus
except ImportError:
dbus = None
_AVAHI_IF_UNSPEC = -1
_AVAHI_PROTO_UNSPEC = -1
_AVAHI_PUBLISHFLAGS_NONE = 0
def _is_loopback_address(host):
return (
host.startswith("127.")
or host.startswith("::ffff:127.")
or host == "::1"
)
def _convert_text_list_to_dbus_format(text_list):
array = dbus.Array(signature="ay")
for text in text_list:
array.append([dbus.Byte(ord(c)) for c in text])
return array
[docs]
class Zeroconf:
"""Publish a network service with Zeroconf.
Currently, this only works on Linux using Avahi via D-Bus.
:param str name: human readable name of the service, e.g. 'MPD on neptune'
:param str stype: service type, e.g. '_mpd._tcp'
:param int port: TCP port of the service, e.g. 6600
:param str domain: local network domain name, defaults to ''
:param str host: interface to advertise the service on, defaults to ''
:param text: extra information depending on ``stype``, defaults to empty
list
:type text: list of str
"""
def __init__(self, name, stype, port, domain="", host="", text=None):
self.stype = stype
self.port = port
self.domain = domain
self.host = host
self.text = text or []
self.bus = None
self.server = None
self.group = None
self.display_hostname = None
self.name = None
if dbus:
try:
self.bus = dbus.SystemBus()
self.server = dbus.Interface(
self.bus.get_object("org.freedesktop.Avahi", "/"),
"org.freedesktop.Avahi.Server",
)
self.display_hostname = f"{self.server.GetHostName()}"
self.name = string.Template(name).safe_substitute(
hostname=self.display_hostname, port=port
)
except dbus.exceptions.DBusException as e:
logger.debug("%s: Server failed: %s", self, e)
def __str__(self):
return (
f"Zeroconf service {self.name!r} "
f"({self.stype} at [{self.host}]:{self.port:d})"
)
[docs]
def publish(self):
"""Publish the service.
Call when your service starts.
"""
if _is_loopback_address(self.host):
logger.debug(
"%s: Publish on loopback interface is not supported.", self
)
return False
if not dbus:
logger.debug("%s: dbus not installed; publish failed.", self)
return False
if not self.bus:
logger.debug("%s: Bus not available; publish failed.", self)
return False
if not self.server:
logger.debug("%s: Server not available; publish failed.", self)
return False
try:
if not self.bus.name_has_owner("org.freedesktop.Avahi"):
logger.debug(
"%s: Avahi service not running; publish failed.", self
)
return False
self.group = dbus.Interface(
self.bus.get_object(
"org.freedesktop.Avahi", self.server.EntryGroupNew()
),
"org.freedesktop.Avahi.EntryGroup",
)
self.group.AddService(
_AVAHI_IF_UNSPEC,
_AVAHI_PROTO_UNSPEC,
dbus.UInt32(_AVAHI_PUBLISHFLAGS_NONE),
self.name,
self.stype,
self.domain,
self.host,
dbus.UInt16(self.port),
_convert_text_list_to_dbus_format(self.text),
)
self.group.Commit()
logger.debug("%s: Published", self)
return True
except dbus.exceptions.DBusException as e:
logger.debug("%s: Publish failed: %s", self, e)
return False
[docs]
def unpublish(self):
"""Unpublish the service.
Call when your service shuts down.
"""
if not dbus or not self.group:
return
try:
self.group.Reset()
logger.debug("%s: Unpublished", self)
except dbus.exceptions.DBusException as e:
logger.debug("%s: Unpublish failed: %s", self, e)
finally:
self.group = None