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Split Avahi stuff into its own file.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,114 @@ | ||
| import asyncio | ||
| from logging import getLogger | ||
| from typing import Optional | ||
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| LOG = getLogger(__name__) | ||
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| try: | ||
| import dbus | ||
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| class DBusState: | ||
| """Bundle of state for dbus""" | ||
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| def __init__( | ||
| self, | ||
| bus: dbus.SystemBus, | ||
| server: dbus.Interface, | ||
| entrygroup: dbus.Interface, | ||
| ) -> None: | ||
| """ | ||
| Build the state bundle. | ||
| :param bus: The system bus instance | ||
| :param server: An org.freedesktop.Avahi.Server interface | ||
| :param entrygroup: An org.freedesktop.Avahi.EntryGroup interface | ||
| """ | ||
| self.bus = bus | ||
| #: The system bus | ||
| self.entrygroup = entrygroup | ||
| #: The entry group interface | ||
| self.server = server | ||
| #: The avahi server interface | ||
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| _BUS_STATE: Optional[DBusState] = None | ||
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| def _set_avahi_service_name_sync(new_service_name: str) -> None: | ||
| """The synchronous implementation of setting the Avahi service name. | ||
| The dbus module doesn't natively support async/await. | ||
| """ | ||
| # For semantics of the methods we're calling, see Avahi's API docs. | ||
| # For example: https://www.avahi.org/doxygen/html/index.html#good_publish | ||
| # It's mostly in terms of the C API, but the semantics should be the same. | ||
| # | ||
| # For exact method names and argument types, see Avahi's D-Bus bindings, | ||
| # which they specify across several machine-readable files. For example: | ||
| # https://github.com/lathiat/avahi/blob/v0.7/avahi-daemon/org.freedesktop.Avahi.EntryGroup.xml | ||
| global _BUS_STATE | ||
| if not _BUS_STATE: | ||
| bus = dbus.SystemBus() | ||
| server_obj = bus.get_object("org.freedesktop.Avahi", "/") | ||
| server_if = dbus.Interface(server_obj, "org.freedesktop.Avahi.Server") | ||
| entrygroup_path = server_if.EntryGroupNew() | ||
| entrygroup_obj = bus.get_object("org.freedesktop.Avahi", entrygroup_path) | ||
| entrygroup_if = dbus.Interface( | ||
| entrygroup_obj, "org.freedesktop.Avahi.EntryGroup" | ||
| ) | ||
| _BUS_STATE = DBusState(bus, server_if, entrygroup_if) | ||
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| _BUS_STATE.entrygroup.Reset() | ||
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| hostname = _BUS_STATE.server.GetHostName() | ||
| domainname = _BUS_STATE.server.GetDomainName() | ||
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| # TODO(mm, 2022-05-06): This isn't exception-safe. | ||
| # Since we've already reset the entrygroup, if this fails | ||
| # (for example because Avahi doesn't like the new name), | ||
| # we'll be left with no entrygroup and Avahi will stop advertising the machine. | ||
| _BUS_STATE.entrygroup.AddService( | ||
| dbus.Int32(-1), # avahi.IF_UNSPEC | ||
| dbus.Int32(-1), # avahi.PROTO_UNSPEC | ||
| dbus.UInt32(0), # flags | ||
| new_service_name, # sname | ||
| "_http._tcp", # stype | ||
| domainname, # sdomain (.local) | ||
| f"{hostname}.{domainname}", # shost (hostname.local) | ||
| dbus.UInt16(31950), # port | ||
| dbus.Array([], signature="ay"), | ||
| ) | ||
| _BUS_STATE.entrygroup.Commit() | ||
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| # TODO(mm, 2022-05-04): Recover from AVAHI_ENTRY_GROUP_COLLISION in case | ||
| # this name collides with another device on the network. | ||
| # https://github.com/Opentrons/opentrons/issues/10126 | ||
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| except ImportError: | ||
| LOG.exception("Couldn't import dbus, name setting will be nonfunctional") | ||
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| def _set_avahi_service_name_sync(new_service_name: str) -> None: | ||
| LOG.warning("Not setting name, dbus could not be imported") | ||
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| _BUS_LOCK = asyncio.Lock() | ||
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| async def set_avahi_service_name(new_service_name: str) -> None: | ||
| """Set the Avahi service name. | ||
| The new service name will only apply to the current boot. | ||
| Avahi requires a service name. | ||
| It will not advertise the system over mDNS + DNS-SD until one is set. | ||
| Since the Avahi service name corresponds to the DNS-SD instance name, | ||
| it's a human-readable string of mostly arbitrary Unicode, | ||
| at most 63 octets (not 63 code points or 63 characters!) long. | ||
| (See: https://datatracker.ietf.org/doc/html/rfc6763#section-4.1.1) | ||
| Avahi will raise an error if it thinks the new service name is invalid. | ||
| """ | ||
| async with _BUS_LOCK: | ||
| await asyncio.get_event_loop().run_in_executor( | ||
| None, _set_avahi_service_name_sync, new_service_name | ||
| ) |