sending.add(additional)

def sanitize_incoming_record(record: DNSRecord) -> None:

"""Protect zeroconf from records that can cause denial of service.

We enforce a minimum TTL for PTR records to avoid

ServiceBrowsers generating excessive queries refresh queries.

Apple uses a 15s minimum TTL, however we do not have the same

level of rate limit and safe guards so we use 1/4 of the recommended value.

"""

if record.ttl and record.ttl < _DNS_PTR_MIN_TTL and isinstance(record, DNSPointer):

log.debug(

"Increasing effective ttl of %s to minimum of %s to protect against excessive refreshes.",

record,

_DNS_PTR_MIN_TTL,

)

record.set_created_ttl(record.created, _DNS_PTR_MIN_TTL)

class _QueryResponse:

"""A pair for unicast and multicast DNSOutgoing responses."""

threadsafe.

"""

updates: List[RecordUpdate] = []

address_adds: List[DNSAddress] = []

address_adds: List[DNSRecord] = []

other_adds: List[DNSRecord] = []

removes: Set[DNSRecord] = set()

now = msg.now

unique_types: Set[Tuple[str, int, int]] = set()

for record in msg.answers:

sanitize_incoming_record(record)

# Protect zeroconf from records that can cause denial of service.

#

# We enforce a minimum TTL for PTR records to avoid

# ServiceBrowsers generating excessive queries refresh queries.

# Apple uses a 15s minimum TTL, however we do not have the same

# level of rate limit and safe guards so we use 1/4 of the recommended value.

if record.ttl and record.type == _TYPE_PTR and record.ttl < _DNS_PTR_MIN_TTL:

log.debug(

"Increasing effective ttl of %s to minimum of %s to protect against excessive refreshes.",

record,

_DNS_PTR_MIN_TTL,

)

record.set_created_ttl(record.created, _DNS_PTR_MIN_TTL)

if record.unique: # https://tools.ietf.org/html/rfc6762#section-10.2

unique_types.add((record.name, record.type, record.class_))

if maybe_entry is not None:

maybe_entry.reset_ttl(record)

else:

if isinstance(record, DNSAddress):

if record.type in _ADDRESS_RECORD_TYPES:

address_adds.append(record)

else:

other_adds.append(record)