diff options
Diffstat (limited to 'staslib/avahi.py')
| -rw-r--r-- | staslib/avahi.py | 456 |
1 files changed, 456 insertions, 0 deletions
diff --git a/staslib/avahi.py b/staslib/avahi.py new file mode 100644 index 0000000..c8a3a0b --- /dev/null +++ b/staslib/avahi.py @@ -0,0 +1,456 @@ +# Copyright (c) 2021, Dell Inc. or its subsidiaries. All rights reserved. +# SPDX-License-Identifier: Apache-2.0 +# See the LICENSE file for details. +# +# This file is part of NVMe STorage Appliance Services (nvme-stas). +# +# Authors: Martin Belanger <Martin.Belanger@dell.com> +# +''' Module that provides a way to retrieve discovered + services from the Avahi daemon over D-Bus. +''' +import socket +import typing +import logging +import functools +import dasbus.error +import dasbus.connection +import dasbus.client.proxy +import dasbus.client.observer +from gi.repository import GLib +from staslib import defs, conf, gutil + + +def _txt2dict(txt: list): + '''@param txt: A list of list of integers. The integers are the ASCII value + of printable text characters. + ''' + the_dict = dict() + for list_of_chars in txt: + try: + string = functools.reduce(lambda accumulator, c: accumulator + chr(c), list_of_chars, '') + key, val = string.split("=") + the_dict[key.lower()] = val + except Exception: # pylint: disable=broad-except + pass + + return the_dict + + +def _proto2trans(protocol): + '''Return the matching transport for the given protocol.''' + if protocol is None: + return None + + protocol = protocol.strip().lower() + if protocol == 'tcp': + return 'tcp' + + if protocol in ('roce', 'iwarp', 'rdma'): + return 'rdma' + + return None + + +# ****************************************************************************** +class Avahi: # pylint: disable=too-many-instance-attributes + '''@brief Avahi Server proxy. Set up the D-Bus connection to the Avahi + daemon and register to be notified when services of a certain + type (stype) are discovered or lost. + ''' + + DBUS_NAME = 'org.freedesktop.Avahi' + DBUS_INTERFACE_SERVICE_BROWSER = DBUS_NAME + '.ServiceBrowser' + DBUS_INTERFACE_SERVICE_RESOLVER = DBUS_NAME + '.ServiceResolver' + LOOKUP_USE_MULTICAST = 2 + + IF_UNSPEC = -1 + PROTO_INET = 0 + PROTO_INET6 = 1 + PROTO_UNSPEC = -1 + + LOOKUP_RESULT_LOCAL = 8 # This record/service resides on and was announced by the local host + LOOKUP_RESULT_CACHED = 1 # This response originates from the cache + LOOKUP_RESULT_STATIC = 32 # The returned data has been defined statically by some configuration option + LOOKUP_RESULT_OUR_OWN = 16 # This service belongs to the same local client as the browser object + LOOKUP_RESULT_WIDE_AREA = 2 # This response originates from wide area DNS + LOOKUP_RESULT_MULTICAST = 4 # This response originates from multicast DNS + + result_flags = { + LOOKUP_RESULT_LOCAL: 'local', + LOOKUP_RESULT_CACHED: 'cache', + LOOKUP_RESULT_STATIC: 'static', + LOOKUP_RESULT_OUR_OWN: 'own', + LOOKUP_RESULT_WIDE_AREA: 'wan', + LOOKUP_RESULT_MULTICAST: 'mcast', + } + + protos = {PROTO_INET: 'IPv4', PROTO_INET6: 'IPv6', PROTO_UNSPEC: 'uspecified'} + + @classmethod + def result_flags_as_string(cls, flags): + '''Convert flags to human-readable string''' + return '+'.join((value for flag, value in Avahi.result_flags.items() if (flags & flag) != 0)) + + @classmethod + def protocol_as_string(cls, proto): + '''Convert protocol codes to human-readable strings''' + return Avahi.protos.get(proto, 'unknown') + + # ========================================================================== + def __init__(self, sysbus, change_cb): + self._change_cb = change_cb + self._services = dict() + self._sysbus = sysbus + self._stypes = set() + self._service_browsers = dict() + + # Avahi is an on-demand service. If, for some reason, the avahi-daemon + # were to stop, we need to try to contact it for it to restart. For + # example, when installing the avahi-daemon package on a running system, + # the daemon doesn't get started right away. It needs another process to + # access it over D-Bus to wake it up. The following timer is used to + # periodically query the avahi-daemon until we successfully establish + # first contact. + self._kick_avahi_tmr = gutil.GTimer(60, self._on_kick_avahi) + + # Subscribe for Avahi signals (i.e. events). This must be done before + # any Browser or Resolver is created to avoid race conditions and + # missed events. + self._subscriptions = [ + self._sysbus.connection.signal_subscribe( + Avahi.DBUS_NAME, + Avahi.DBUS_INTERFACE_SERVICE_BROWSER, + 'ItemNew', + None, + None, + 0, + self._service_discovered, + ), + self._sysbus.connection.signal_subscribe( + Avahi.DBUS_NAME, + Avahi.DBUS_INTERFACE_SERVICE_BROWSER, + 'ItemRemove', + None, + None, + 0, + self._service_removed, + ), + self._sysbus.connection.signal_subscribe( + Avahi.DBUS_NAME, Avahi.DBUS_INTERFACE_SERVICE_BROWSER, 'Failure', None, None, 0, self._failure_handler + ), + self._sysbus.connection.signal_subscribe( + Avahi.DBUS_NAME, Avahi.DBUS_INTERFACE_SERVICE_RESOLVER, 'Found', None, None, 0, self._service_identified + ), + self._sysbus.connection.signal_subscribe( + Avahi.DBUS_NAME, Avahi.DBUS_INTERFACE_SERVICE_RESOLVER, 'Failure', None, None, 0, self._failure_handler + ), + ] + + self._avahi = self._sysbus.get_proxy(Avahi.DBUS_NAME, '/') + + self._avahi_watcher = dasbus.client.observer.DBusObserver(self._sysbus, Avahi.DBUS_NAME) + self._avahi_watcher.service_available.connect(self._avahi_available) + self._avahi_watcher.service_unavailable.connect(self._avahi_unavailable) + self._avahi_watcher.connect_once_available() + + def kill(self): + '''@brief Clean up object''' + logging.debug('Avahi.kill()') + + self._kick_avahi_tmr.kill() + self._kick_avahi_tmr = None + + for subscription in self._subscriptions: + self._sysbus.connection.signal_unsubscribe(subscription) + self._subscriptions = list() + + self._disconnect() + + self._avahi_watcher.service_available.disconnect() + self._avahi_watcher.service_unavailable.disconnect() + self._avahi_watcher.disconnect() + self._avahi_watcher = None + + dasbus.client.proxy.disconnect_proxy(self._avahi) + self._avahi = None + + self._change_cb = None + self._sysbus = None + + def info(self) -> dict: + '''@brief return debug info about this object''' + services = dict() + for service, obj in self._services.items(): + interface, protocol, name, stype, domain = service + key = f'({socket.if_indextoname(interface)}, {Avahi.protos.get(protocol, "unknown")}, {name}.{domain}, {stype})' + services[key] = obj.get('data', {}) + + info = { + 'avahi wake up timer': str(self._kick_avahi_tmr), + 'service types': list(self._stypes), + 'services': services, + } + + return info + + def get_controllers(self) -> list: + '''@brief Get the discovery controllers as a list of dict() + as follows: + [ + { + 'transport': tcp, + 'traddr': str(), + 'trsvcid': str(), + 'host-iface': str(), + 'subsysnqn': 'nqn.2014-08.org.nvmexpress.discovery', + }, + { + 'transport': tcp, + 'traddr': str(), + 'trsvcid': str(), + 'host-iface': str(), + 'subsysnqn': 'nqn.2014-08.org.nvmexpress.discovery', + }, + [...] + ] + ''' + return [service['data'] for service in self._services.values() if len(service['data'])] + + def config_stypes(self, stypes: list): + '''@brief Configure the service types that we want to discover. + @param stypes: A list of services types, e.g. ['_nvme-disc._tcp'] + ''' + self._stypes = set(stypes) + success = self._configure_browsers() + if not success: + self._kick_avahi_tmr.start() + + def kick_start(self): + '''@brief We use this to kick start the Avahi + daemon (i.e. socket activation). + ''' + self._kick_avahi_tmr.clear() + + def _disconnect(self): + logging.debug('Avahi._disconnect()') + for service in self._services.values(): + resolver = service.pop('resolver', None) + if resolver is not None: + try: + resolver.Free() + dasbus.client.proxy.disconnect_proxy(resolver) + except (AttributeError, dasbus.error.DBusError) as ex: + logging.debug('Avahi._disconnect() - Failed to Free() resolver. %s', ex) + + self._services = dict() + + for browser in self._service_browsers.values(): + try: + browser.Free() + dasbus.client.proxy.disconnect_proxy(browser) + except (AttributeError, dasbus.error.DBusError) as ex: + logging.debug('Avahi._disconnect() - Failed to Free() browser. %s', ex) + + self._service_browsers = dict() + + def _on_kick_avahi(self): + try: + # try to contact avahi-daemon. This is just a wake + # up call in case the avahi-daemon was sleeping. + self._avahi.GetVersionString() + except dasbus.error.DBusError: + return GLib.SOURCE_CONTINUE + + return GLib.SOURCE_REMOVE + + def _avahi_available(self, _avahi_watcher): + '''@brief Hook up DBus signal handlers for signals from stafd.''' + logging.info('avahi-daemon service available, zeroconf supported.') + success = self._configure_browsers() + if not success: + self._kick_avahi_tmr.start() + + def _avahi_unavailable(self, _avahi_watcher): + self._disconnect() + logging.warning('avahi-daemon not available, zeroconf not supported.') + self._kick_avahi_tmr.start() + + def _configure_browsers(self): + stypes_cur = set(self._service_browsers.keys()) + stypes_to_add = self._stypes - stypes_cur + stypes_to_rm = stypes_cur - self._stypes + + logging.debug('Avahi._configure_browsers() - stypes_to_rm = %s', list(stypes_to_rm)) + logging.debug('Avahi._configure_browsers() - stypes_to_add = %s', list(stypes_to_add)) + + for stype_to_rm in stypes_to_rm: + browser = self._service_browsers.pop(stype_to_rm, None) + if browser is not None: + try: + browser.Free() + dasbus.client.proxy.disconnect_proxy(browser) + except (AttributeError, dasbus.error.DBusError) as ex: + logging.debug('Avahi._configure_browsers() - Failed to Free() browser. %s', ex) + + # Find the cached services corresponding to stype_to_rm and remove them + services_to_rm = [service for service in self._services if service[3] == stype_to_rm] + for service in services_to_rm: + resolver = self._services.pop(service, {}).pop('resolver', None) + if resolver is not None: + try: + resolver.Free() + dasbus.client.proxy.disconnect_proxy(resolver) + except (AttributeError, dasbus.error.DBusError) as ex: + logging.debug('Avahi._configure_browsers() - Failed to Free() resolver. %s', ex) + + for stype in stypes_to_add: + try: + obj_path = self._avahi.ServiceBrowserNew( + Avahi.IF_UNSPEC, Avahi.PROTO_UNSPEC, stype, 'local', Avahi.LOOKUP_USE_MULTICAST + ) + self._service_browsers[stype] = self._sysbus.get_proxy(Avahi.DBUS_NAME, obj_path) + except dasbus.error.DBusError as ex: + logging.debug('Avahi._configure_browsers() - Failed to contact avahi-daemon. %s', ex) + logging.warning('avahi-daemon not available, operating w/o mDNS discovery.') + return False + + return True + + def _service_discovered( + self, + _connection, + _sender_name: str, + _object_path: str, + _interface_name: str, + _signal_name: str, + args: typing.Tuple[int, int, str, str, str, int], + *_user_data, + ): + (interface, protocol, name, stype, domain, flags) = args + logging.debug( + 'Avahi._service_discovered() - interface=%s (%s), protocol=%s, stype=%s, domain=%s, flags=%s %-14s name=%s', + interface, + socket.if_indextoname(interface), + Avahi.protocol_as_string(protocol), + stype, + domain, + flags, + '(' + Avahi.result_flags_as_string(flags) + '),', + name, + ) + + service = (interface, protocol, name, stype, domain) + if service not in self._services: + try: + obj_path = self._avahi.ServiceResolverNew( + interface, protocol, name, stype, domain, Avahi.PROTO_UNSPEC, Avahi.LOOKUP_USE_MULTICAST + ) + self._services[service] = { + 'resolver': self._sysbus.get_proxy(Avahi.DBUS_NAME, obj_path), + 'data': {}, + } + except dasbus.error.DBusError as ex: + logging.warning('Failed to create resolver: "%s", "%s", "%s". %s', interface, name, stype, ex) + + def _service_removed( + self, + _connection, + _sender_name: str, + _object_path: str, + _interface_name: str, + _signal_name: str, + args: typing.Tuple[int, int, str, str, str, int], + *_user_data, + ): + (interface, protocol, name, stype, domain, flags) = args + logging.debug( + 'Avahi._service_removed() - interface=%s (%s), protocol=%s, stype=%s, domain=%s, flags=%s %-14s name=%s', + interface, + socket.if_indextoname(interface), + Avahi.protocol_as_string(protocol), + stype, + domain, + flags, + '(' + Avahi.result_flags_as_string(flags) + '),', + name, + ) + + service = (interface, protocol, name, stype, domain) + resolver = self._services.pop(service, {}).pop('resolver', None) + if resolver is not None: + try: + resolver.Free() + dasbus.client.proxy.disconnect_proxy(resolver) + except (AttributeError, dasbus.error.DBusError) as ex: + logging.debug('Avahi._service_removed() - Failed to Free() resolver. %s', ex) + + self._change_cb() + + def _service_identified( # pylint: disable=too-many-locals + self, + _connection, + _sender_name: str, + _object_path: str, + _interface_name: str, + _signal_name: str, + args: typing.Tuple[int, int, str, str, str, str, int, str, int, list, int], + *_user_data, + ): + (interface, protocol, name, stype, domain, host, aprotocol, address, port, txt, flags) = args + txt = _txt2dict(txt) + logging.debug( + 'Avahi._service_identified() - interface=%s (%s), protocol=%s, stype=%s, domain=%s, flags=%s %-14s name=%s, host=%s, aprotocol=%s, address=%s, port=%s, txt=%s', + interface, + socket.if_indextoname(interface), + Avahi.protocol_as_string(protocol), + stype, + domain, + flags, + '(' + Avahi.result_flags_as_string(flags) + '),', + name, + host, + Avahi.protocol_as_string(aprotocol), + address, + port, + txt, + ) + + service = (interface, protocol, name, stype, domain) + if service in self._services: + transport = _proto2trans(txt.get('p')) + if transport is not None: + self._services[service]['data'] = { + 'transport': transport, + 'traddr': address.strip(), + 'trsvcid': str(port).strip(), + # host-iface permitted for tcp alone and not rdma + 'host-iface': socket.if_indextoname(interface).strip() if transport == 'tcp' else '', + 'subsysnqn': txt.get('nqn', defs.WELL_KNOWN_DISC_NQN).strip() + if conf.NvmeOptions().discovery_supp + else defs.WELL_KNOWN_DISC_NQN, + } + + self._change_cb() + else: + logging.error( + 'Received invalid/undefined protocol in mDNS TXT field: address=%s, iface=%s, TXT=%s', + address, + socket.if_indextoname(interface).strip(), + txt, + ) + + def _failure_handler( # pylint: disable=no-self-use + self, + _connection, + _sender_name: str, + _object_path: str, + interface_name: str, + _signal_name: str, + args: typing.Tuple[str], + *_user_data, + ): + (error,) = args + if 'ServiceResolver' not in interface_name or 'TimeoutError' not in error: + # ServiceResolver may fire a timeout event after being Free'd(). This seems to be normal. + logging.error('Avahi._failure_handler() - name=%s, error=%s', interface_name, error) |