""" Multicast DNS Service Discovery for Python, v0.14-wmcbrine
Copyright 2003 Paul Scott-Murphy, 2014 William McBrine
This module provides a framework for the use of DNS Service Discovery
using IP multicast.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
USA
"""
import enum
import errno
import ipaddress
import itertools
import logging
import os
import platform
import re
import select
import socket
import struct
import sys
import threading
import time
import warnings
from collections import OrderedDict
from typing import Any, Callable, Set, Tuple # noqa # used in type hints
from typing import Dict, List, Optional, Sequence, Union, cast
import ifaddr
__author__ = 'Paul Scott-Murphy, William McBrine'
__maintainer__ = 'Jakub Stasiak <jakub@stasiak.at>'
__version__ = '0.26.1'
__license__ = 'LGPL'
__all__ = [
"__version__",
"Zeroconf",
"ServiceInfo",
"ServiceBrowser",
"Error",
"InterfaceChoice",
"ServiceStateChange",
"IPVersion",
]
if sys.version_info <= (3, 3):
raise ImportError(
'''
Python version > 3.3 required for python-zeroconf.
If you need support for Python 2 or Python 3.3 please use version 19.1
'''
)
log = logging.getLogger(__name__)
log.addHandler(logging.NullHandler())
if log.level == logging.NOTSET:
log.setLevel(logging.WARN)
# Some timing constants
_UNREGISTER_TIME = 125 # ms
_CHECK_TIME = 175 # ms
_REGISTER_TIME = 225 # ms
_LISTENER_TIME = 200 # ms
_BROWSER_TIME = 1000 # ms
_BROWSER_BACKOFF_LIMIT = 3600 # s
# Some DNS constants
_MDNS_ADDR = '224.0.0.251'
_MDNS_ADDR_BYTES = socket.inet_aton(_MDNS_ADDR)
_MDNS_ADDR6 = 'ff02::fb'
_MDNS_ADDR6_BYTES = socket.inet_pton(socket.AF_INET6, _MDNS_ADDR6)
_MDNS_PORT = 5353
_DNS_PORT = 53
_DNS_HOST_TTL = 120 # two minute for host records (A, SRV etc) as-per RFC6762
_DNS_OTHER_TTL = 4500 # 75 minutes for non-host records (PTR, TXT etc) as-per RFC6762
_MAX_MSG_TYPICAL = 1460 # unused
_MAX_MSG_ABSOLUTE = 8966
_FLAGS_QR_MASK = 0x8000 # query response mask
_FLAGS_QR_QUERY = 0x0000 # query
_FLAGS_QR_RESPONSE = 0x8000 # response
_FLAGS_AA = 0x0400 # Authoritative answer
_FLAGS_TC = 0x0200 # Truncated
_FLAGS_RD = 0x0100 # Recursion desired
_FLAGS_RA = 0x8000 # Recursion available
_FLAGS_Z = 0x0040 # Zero
_FLAGS_AD = 0x0020 # Authentic data
_FLAGS_CD = 0x0010 # Checking disabled
_CLASS_IN = 1
_CLASS_CS = 2
_CLASS_CH = 3
_CLASS_HS = 4
_CLASS_NONE = 254
_CLASS_ANY = 255
_CLASS_MASK = 0x7FFF
_CLASS_UNIQUE = 0x8000
_TYPE_A = 1
_TYPE_NS = 2
_TYPE_MD = 3
_TYPE_MF = 4
_TYPE_CNAME = 5
_TYPE_SOA = 6
_TYPE_MB = 7
_TYPE_MG = 8
_TYPE_MR = 9
_TYPE_NULL = 10
_TYPE_WKS = 11
_TYPE_PTR = 12
_TYPE_HINFO = 13
_TYPE_MINFO = 14
_TYPE_MX = 15
_TYPE_TXT = 16
_TYPE_AAAA = 28
_TYPE_SRV = 33
_TYPE_ANY = 255
# Mapping constants to names
_CLASSES = {
_CLASS_IN: "in",
_CLASS_CS: "cs",
_CLASS_CH: "ch",
_CLASS_HS: "hs",
_CLASS_NONE: "none",
_CLASS_ANY: "any",
}
_TYPES = {
_TYPE_A: "a",
_TYPE_NS: "ns",
_TYPE_MD: "md",
_TYPE_MF: "mf",
_TYPE_CNAME: "cname",
_TYPE_SOA: "soa",
_TYPE_MB: "mb",
_TYPE_MG: "mg",
_TYPE_MR: "mr",
_TYPE_NULL: "null",
_TYPE_WKS: "wks",
_TYPE_PTR: "ptr",
_TYPE_HINFO: "hinfo",
_TYPE_MINFO: "minfo",
_TYPE_MX: "mx",
_TYPE_TXT: "txt",
_TYPE_AAAA: "quada",
_TYPE_SRV: "srv",
_TYPE_ANY: "any",
}
_HAS_A_TO_Z = re.compile(r'[A-Za-z]')
_HAS_ONLY_A_TO_Z_NUM_HYPHEN = re.compile(r'^[A-Za-z0-9\-]+$')
_HAS_ONLY_A_TO_Z_NUM_HYPHEN_UNDERSCORE = re.compile(r'^[A-Za-z0-9\-\_]+$')
_HAS_ASCII_CONTROL_CHARS = re.compile(r'[\x00-\x1f\x7f]')
try:
_IPPROTO_IPV6 = socket.IPPROTO_IPV6
except AttributeError:
# Sigh: https://bugs.python.org/issue29515
_IPPROTO_IPV6 = 41
int2byte = struct.Struct(">B").pack
[文档]@enum.unique
class InterfaceChoice(enum.Enum):
Default = 1
All = 2
InterfacesType = Union[List[Union[str, int]], InterfaceChoice]
[文档]@enum.unique
class ServiceStateChange(enum.Enum):
Added = 1
Removed = 2
Updated = 3
[文档]@enum.unique
class IPVersion(enum.Enum):
V4Only = 1
V6Only = 2
All = 3
# utility functions
def current_time_millis() -> float:
"""Current system time in milliseconds"""
return time.time() * 1000
def _is_v6_address(addr: bytes) -> bool:
return len(addr) == 16
def service_type_name(type_: str, *, allow_underscores: bool = False) -> str:
"""
Validate a fully qualified service name, instance or subtype. [rfc6763]
Returns fully qualified service name.
Domain names used by mDNS-SD take the following forms:
<sn> . <_tcp|_udp> . local.
<Instance> . <sn> . <_tcp|_udp> . local.
<sub>._sub . <sn> . <_tcp|_udp> . local.
1) must end with 'local.'
This is true because we are implementing mDNS and since the 'm' means
multi-cast, the 'local.' domain is mandatory.
2) local is preceded with either '_udp.' or '_tcp.'
3) service name <sn> precedes <_tcp|_udp>
The rules for Service Names [RFC6335] state that they may be no more
than fifteen characters long (not counting the mandatory underscore),
consisting of only letters, digits, and hyphens, must begin and end
with a letter or digit, must not contain consecutive hyphens, and
must contain at least one letter.
The instance name <Instance> and sub type <sub> may be up to 63 bytes.
The portion of the Service Instance Name is a user-
friendly name consisting of arbitrary Net-Unicode text [RFC5198]. It
MUST NOT contain ASCII control characters (byte values 0x00-0x1F and
0x7F) [RFC20] but otherwise is allowed to contain any characters,
without restriction, including spaces, uppercase, lowercase,
punctuation -- including dots -- accented characters, non-Roman text,
and anything else that may be represented using Net-Unicode.
:param type_: Type, SubType or service name to validate
:return: fully qualified service name (eg: _http._tcp.local.)
"""
if not (type_.endswith('._tcp.local.') or type_.endswith('._udp.local.')):
raise BadTypeInNameException("Type '%s' must end with '._tcp.local.' or '._udp.local.'" % type_)
remaining = type_[: -len('._tcp.local.')].split('.')
name = remaining.pop()
if not name:
raise BadTypeInNameException("No Service name found")
if len(remaining) == 1 and len(remaining[0]) == 0:
raise BadTypeInNameException("Type '%s' must not start with '.'" % type_)
if name[0] != '_':
raise BadTypeInNameException("Service name (%s) must start with '_'" % name)
# remove leading underscore
name = name[1:]
if len(name) > 60:
raise BadTypeInNameException("Service name (%s) must be <= 15 bytes" % name)
if '--' in name:
raise BadTypeInNameException("Service name (%s) must not contain '--'" % name)
if '-' in (name[0], name[-1]):
raise BadTypeInNameException("Service name (%s) may not start or end with '-'" % name)
if not _HAS_A_TO_Z.search(name):
raise BadTypeInNameException("Service name (%s) must contain at least one letter (eg: 'A-Z')" % name)
allowed_characters_re = (
_HAS_ONLY_A_TO_Z_NUM_HYPHEN_UNDERSCORE if allow_underscores else _HAS_ONLY_A_TO_Z_NUM_HYPHEN
)
if not allowed_characters_re.search(name):
raise BadTypeInNameException(
"Service name (%s) must contain only these characters: "
"A-Z, a-z, 0-9, hyphen ('-')%s" % (name, ", underscore ('_')" if allow_underscores else "")
)
if remaining and remaining[-1] == '_sub':
remaining.pop()
if len(remaining) == 0 or len(remaining[0]) == 0:
raise BadTypeInNameException("_sub requires a subtype name")
if len(remaining) > 1:
remaining = ['.'.join(remaining)]
if remaining:
length = len(remaining[0].encode('utf-8'))
if length > 63:
raise BadTypeInNameException("Too long: '%s'" % remaining[0])
if _HAS_ASCII_CONTROL_CHARS.search(remaining[0]):
raise BadTypeInNameException(
"Ascii control character 0x00-0x1F and 0x7F illegal in '%s'" % remaining[0]
)
return '_' + name + type_[-len('._tcp.local.'):]
# Exceptions
[文档]class Error(Exception):
pass
class IncomingDecodeError(Error):
pass
class NonUniqueNameException(Error):
pass
class NamePartTooLongException(Error):
pass
class AbstractMethodException(Error):
pass
class BadTypeInNameException(Error):
pass
# implementation classes
class QuietLogger:
_seen_logs = {} # type: Dict[str, Union[int, tuple]]
@classmethod
def log_exception_warning(cls, logger_data: Optional[Tuple] = None) -> None:
exc_info = sys.exc_info()
exc_str = str(exc_info[1])
if exc_str not in cls._seen_logs:
# log at warning level the first time this is seen
cls._seen_logs[exc_str] = exc_info
logger = log.warning
else:
logger = log.debug
if logger_data is not None:
logger(*logger_data)
logger('Exception occurred:', exc_info=True)
@classmethod
def log_warning_once(cls, *args: Any) -> None:
msg_str = args[0]
if msg_str not in cls._seen_logs:
cls._seen_logs[msg_str] = 0
logger = log.warning
else:
logger = log.debug
cls._seen_logs[msg_str] = cast(int, cls._seen_logs[msg_str]) + 1
logger(*args)
class DNSEntry:
"""A DNS entry"""
def __init__(self, name: str, type_: int, class_: int) -> None:
self.key = name.lower()
self.name = name
self.type = type_
self.class_ = class_ & _CLASS_MASK
self.unique = (class_ & _CLASS_UNIQUE) != 0
def __eq__(self, other: Any) -> bool:
"""Equality test on name, type, and class"""
return (
self.name == other.name
and self.type == other.type
and self.class_ == other.class_
and isinstance(other, DNSEntry)
)
def __ne__(self, other: Any) -> bool:
"""Non-equality test"""
return not self.__eq__(other)
@staticmethod
def get_class_(class_: int) -> str:
"""Class accessor"""
return _CLASSES.get(class_, "?(%s)" % class_)
@staticmethod
def get_type(t: int) -> str:
"""Type accessor"""
return _TYPES.get(t, "?(%s)" % t)
def entry_to_string(self, hdr: str, other: Optional[Union[bytes, str]]) -> str:
"""String representation with additional information"""
result = "%s[%s,%s" % (hdr, self.get_type(self.type), self.get_class_(self.class_))
if self.unique:
result += "-unique,"
else:
result += ","
result += self.name
if other is not None:
result += "]=%s" % cast(Any, other)
else:
result += "]"
return result
class DNSQuestion(DNSEntry):
"""A DNS question entry"""
def __init__(self, name: str, type_: int, class_: int) -> None:
DNSEntry.__init__(self, name, type_, class_)
def answered_by(self, rec: 'DNSRecord') -> bool:
"""Returns true if the question is answered by the record"""
return (
self.class_ == rec.class_
and (self.type == rec.type or self.type == _TYPE_ANY)
and self.name == rec.name
)
def __repr__(self) -> str:
"""String representation"""
return DNSEntry.entry_to_string(self, "question", None)
class DNSRecord(DNSEntry):
"""A DNS record - like a DNS entry, but has a TTL"""
# TODO: Switch to just int ttl
def __init__(self, name: str, type_: int, class_: int, ttl: Union[float, int]) -> None:
DNSEntry.__init__(self, name, type_, class_)
self.ttl = ttl
self.created = current_time_millis()
self._expiration_time = self.get_expiration_time(100)
self._stale_time = self.get_expiration_time(50)
def __eq__(self, other: Any) -> bool:
"""Abstract method"""
raise AbstractMethodException
def __ne__(self, other: Any) -> bool:
"""Non-equality test"""
return not self.__eq__(other)
def suppressed_by(self, msg: 'DNSIncoming') -> bool:
"""Returns true if any answer in a message can suffice for the
information held in this record."""
for record in msg.answers:
if self.suppressed_by_answer(record):
return True
return False
def suppressed_by_answer(self, other: 'DNSRecord') -> bool:
"""Returns true if another record has same name, type and class,
and if its TTL is at least half of this record's."""
return self == other and other.ttl > (self.ttl / 2)
def get_expiration_time(self, percent: int) -> float:
"""Returns the time at which this record will have expired
by a certain percentage."""
return self.created + (percent * self.ttl * 10)
# TODO: Switch to just int here
def get_remaining_ttl(self, now: float) -> Union[int, float]:
"""Returns the remaining TTL in seconds."""
return max(0, (self._expiration_time - now) / 1000.0)
def is_expired(self, now: float) -> bool:
"""Returns true if this record has expired."""
return self._expiration_time <= now
def is_stale(self, now: float) -> bool:
"""Returns true if this record is at least half way expired."""
return self._stale_time <= now
def reset_ttl(self, other: 'DNSRecord') -> None:
"""Sets this record's TTL and created time to that of
another record."""
self.created = other.created
self.ttl = other.ttl
self._expiration_time = self.get_expiration_time(100)
self._stale_time = self.get_expiration_time(50)
def write(self, out: 'DNSOutgoing') -> None:
"""Abstract method"""
raise AbstractMethodException
def to_string(self, other: Union[bytes, str]) -> str:
"""String representation with additional information"""
arg = "%s/%s,%s" % (self.ttl, int(self.get_remaining_ttl(current_time_millis())), cast(Any, other))
return DNSEntry.entry_to_string(self, "record", arg)
class DNSAddress(DNSRecord):
"""A DNS address record"""
def __init__(self, name: str, type_: int, class_: int, ttl: int, address: bytes) -> None:
DNSRecord.__init__(self, name, type_, class_, ttl)
self.address = address
def write(self, out: 'DNSOutgoing') -> None:
"""Used in constructing an outgoing packet"""
out.write_string(self.address)
def __eq__(self, other: Any) -> bool:
"""Tests equality on address"""
return (
isinstance(other, DNSAddress) and DNSEntry.__eq__(self, other) and self.address == other.address
)
def __ne__(self, other: Any) -> bool:
"""Non-equality test"""
return not self.__eq__(other)
def __repr__(self) -> str:
"""String representation"""
try:
return self.to_string(
socket.inet_ntop(
socket.AF_INET6 if _is_v6_address(self.address) else socket.AF_INET, self.address
)
)
except Exception: # TODO stop catching all Exceptions
return self.to_string(str(self.address))
class DNSHinfo(DNSRecord):
"""A DNS host information record"""
def __init__(
self, name: str, type_: int, class_: int, ttl: int, cpu: Union[bytes, str], os: Union[bytes, str]
) -> None:
DNSRecord.__init__(self, name, type_, class_, ttl)
try:
self.cpu = cast(bytes, cpu).decode('utf-8')
except AttributeError:
self.cpu = cast(str, cpu)
try:
self.os = cast(bytes, os).decode('utf-8')
except AttributeError:
self.os = cast(str, os)
def write(self, out: 'DNSOutgoing') -> None:
"""Used in constructing an outgoing packet"""
out.write_character_string(self.cpu.encode('utf-8'))
out.write_character_string(self.os.encode('utf-8'))
def __eq__(self, other: Any) -> bool:
"""Tests equality on cpu and os"""
return (
isinstance(other, DNSHinfo)
and DNSEntry.__eq__(self, other)
and self.cpu == other.cpu
and self.os == other.os
)
def __ne__(self, other: Any) -> bool:
"""Non-equality test"""
return not self.__eq__(other)
def __repr__(self) -> str:
"""String representation"""
return self.to_string(self.cpu + " " + self.os)
class DNSPointer(DNSRecord):
"""A DNS pointer record"""
def __init__(self, name: str, type_: int, class_: int, ttl: int, alias: str) -> None:
DNSRecord.__init__(self, name, type_, class_, ttl)
self.alias = alias
def write(self, out: 'DNSOutgoing') -> None:
"""Used in constructing an outgoing packet"""
out.write_name(self.alias)
def __eq__(self, other: Any) -> bool:
"""Tests equality on alias"""
return isinstance(other, DNSPointer) and self.alias == other.alias and DNSEntry.__eq__(self, other)
def __ne__(self, other: Any) -> bool:
"""Non-equality test"""
return not self.__eq__(other)
def __repr__(self) -> str:
"""String representation"""
return self.to_string(self.alias)
class DNSText(DNSRecord):
"""A DNS text record"""
def __init__(self, name: str, type_: int, class_: int, ttl: int, text: bytes) -> None:
assert isinstance(text, (bytes, type(None)))
DNSRecord.__init__(self, name, type_, class_, ttl)
self.text = text
def write(self, out: 'DNSOutgoing') -> None:
"""Used in constructing an outgoing packet"""
out.write_string(self.text)
def __eq__(self, other: Any) -> bool:
"""Tests equality on text"""
return isinstance(other, DNSText) and self.text == other.text and DNSEntry.__eq__(self, other)
def __ne__(self, other: Any) -> bool:
"""Non-equality test"""
return not self.__eq__(other)
def __repr__(self) -> str:
"""String representation"""
if len(self.text) > 10:
return self.to_string(self.text[:7]) + "..."
else:
return self.to_string(self.text)
class DNSService(DNSRecord):
"""A DNS service record"""
def __init__(
self,
name: str,
type_: int,
class_: int,
ttl: Union[float, int],
priority: int,
weight: int,
port: int,
server: str,
) -> None:
DNSRecord.__init__(self, name, type_, class_, ttl)
self.priority = priority
self.weight = weight
self.port = port
self.server = server
def write(self, out: 'DNSOutgoing') -> None:
"""Used in constructing an outgoing packet"""
out.write_short(self.priority)
out.write_short(self.weight)
out.write_short(self.port)
out.write_name(self.server)
def __eq__(self, other: Any) -> bool:
"""Tests equality on priority, weight, port and server"""
return (
isinstance(other, DNSService)
and self.priority == other.priority
and self.weight == other.weight
and self.port == other.port
and self.server == other.server
and DNSEntry.__eq__(self, other)
)
def __ne__(self, other: Any) -> bool:
"""Non-equality test"""
return not self.__eq__(other)
def __repr__(self) -> str:
"""String representation"""
return self.to_string("%s:%s" % (self.server, self.port))
class DNSIncoming(QuietLogger):
"""Object representation of an incoming DNS packet"""
def __init__(self, data: bytes) -> None:
"""Constructor from string holding bytes of packet"""
self.offset = 0
self.data = data
self.questions = [] # type: List[DNSQuestion]
self.answers = [] # type: List[DNSRecord]
self.id = 0
self.flags = 0 # type: int
self.num_questions = 0
self.num_answers = 0
self.num_authorities = 0
self.num_additionals = 0
self.valid = False
try:
self.read_header()
self.read_questions()
self.read_others()
self.valid = True
except (IndexError, struct.error, IncomingDecodeError):
self.log_exception_warning(('Choked at offset %d while unpacking %r', self.offset, data))
def unpack(self, format_: bytes) -> tuple:
length = struct.calcsize(format_)
info = struct.unpack(format_, self.data[self.offset: self.offset + length])
self.offset += length
return info
def read_header(self) -> None:
"""Reads header portion of packet"""
(
self.id,
self.flags,
self.num_questions,
self.num_answers,
self.num_authorities,
self.num_additionals,
) = self.unpack(b'!6H')
def read_questions(self) -> None:
"""Reads questions section of packet"""
for i in range(self.num_questions):
name = self.read_name()
type_, class_ = self.unpack(b'!HH')
question = DNSQuestion(name, type_, class_)
self.questions.append(question)
# def read_int(self):
# """Reads an integer from the packet"""
# return self.unpack(b'!I')[0]
def read_character_string(self) -> bytes:
"""Reads a character string from the packet"""
length = self.data[self.offset]
self.offset += 1
return self.read_string(length)
def read_string(self, length: int) -> bytes:
"""Reads a string of a given length from the packet"""
info = self.data[self.offset: self.offset + length]
self.offset += length
return info
def read_unsigned_short(self) -> int:
"""Reads an unsigned short from the packet"""
return cast(int, self.unpack(b'!H')[0])
def read_others(self) -> None:
"""Reads the answers, authorities and additionals section of the
packet"""
n = self.num_answers + self.num_authorities + self.num_additionals
for i in range(n):
domain = self.read_name()
type_, class_, ttl, length = self.unpack(b'!HHiH')
rec = None # type: Optional[DNSRecord]
if type_ == _TYPE_A:
rec = DNSAddress(domain, type_, class_, ttl, self.read_string(4))
elif type_ == _TYPE_CNAME or type_ == _TYPE_PTR:
rec = DNSPointer(domain, type_, class_, ttl, self.read_name())
elif type_ == _TYPE_TXT:
rec = DNSText(domain, type_, class_, ttl, self.read_string(length))
elif type_ == _TYPE_SRV:
rec = DNSService(
domain,
type_,
class_,
ttl,
self.read_unsigned_short(),
self.read_unsigned_short(),
self.read_unsigned_short(),
self.read_name(),
)
elif type_ == _TYPE_HINFO:
rec = DNSHinfo(
domain, type_, class_, ttl, self.read_character_string(), self.read_character_string()
)
elif type_ == _TYPE_AAAA:
rec = DNSAddress(domain, type_, class_, ttl, self.read_string(16))
else:
# Try to ignore types we don't know about
# Skip the payload for the resource record so the next
# records can be parsed correctly
self.offset += length
if rec is not None:
self.answers.append(rec)
def is_query(self) -> bool:
"""Returns true if this is a query"""
return (self.flags & _FLAGS_QR_MASK) == _FLAGS_QR_QUERY
def is_response(self) -> bool:
"""Returns true if this is a response"""
return (self.flags & _FLAGS_QR_MASK) == _FLAGS_QR_RESPONSE
def read_utf(self, offset: int, length: int) -> str:
"""Reads a UTF-8 string of a given length from the packet"""
return str(self.data[offset: offset + length], 'utf-8', 'replace')
def read_name(self) -> str:
"""Reads a domain name from the packet"""
result = ''
off = self.offset
next_ = -1
first = off
while True:
length = self.data[off]
off += 1
if length == 0:
break
t = length & 0xC0
if t == 0x00:
result = ''.join((result, self.read_utf(off, length) + '.'))
off += length
elif t == 0xC0:
if next_ < 0:
next_ = off + 1
off = ((length & 0x3F) << 8) | self.data[off]
if off >= first:
raise IncomingDecodeError("Bad domain name (circular) at %s" % (off,))
first = off
else:
raise IncomingDecodeError("Bad domain name at %s" % (off,))
if next_ >= 0:
self.offset = next_
else:
self.offset = off
return result
class DNSOutgoing:
"""Object representation of an outgoing packet"""
def __init__(self, flags: int, multicast: bool = True) -> None:
self.finished = False
self.id = 0
self.multicast = multicast
self.flags = flags
self.names = {} # type: Dict[str, int]
self.data = [] # type: List[bytes]
self.size = 12
self.state = self.State.init
self.questions = [] # type: List[DNSQuestion]
self.answers = [] # type: List[Tuple[DNSRecord, float]]
self.authorities = [] # type: List[DNSPointer]
self.additionals = [] # type: List[DNSRecord]
def __repr__(self) -> str:
return '<DNSOutgoing:{%s}>' % ', '.join(
[
'multicast=%s' % self.multicast,
'flags=%s' % self.flags,
'questions=%s' % self.questions,
'answers=%s' % self.answers,
'authorities=%s' % self.authorities,
'additionals=%s' % self.additionals,
]
)
class State(enum.Enum):
init = 0
finished = 1
@staticmethod
def is_type_unique(type_: int) -> bool:
return type_ == _TYPE_TXT or type_ == _TYPE_SRV or type_ == _TYPE_A or type_ == _TYPE_AAAA
def add_question(self, record: DNSQuestion) -> None:
"""Adds a question"""
self.questions.append(record)
def add_answer(self, inp: DNSIncoming, record: DNSRecord) -> None:
"""Adds an answer"""
if not record.suppressed_by(inp):
self.add_answer_at_time(record, 0)
def add_answer_at_time(self, record: Optional[DNSRecord], now: Union[float, int]) -> None:
"""Adds an answer if it does not expire by a certain time"""
if record is not None:
if now == 0 or not record.is_expired(now):
self.answers.append((record, now))
def add_authorative_answer(self, record: DNSPointer) -> None:
"""Adds an authoritative answer"""
self.authorities.append(record)
def add_additional_answer(self, record: DNSRecord) -> None:
""" Adds an additional answer
From: RFC 6763, DNS-Based Service Discovery, February 2013
12. DNS Additional Record Generation
DNS has an efficiency feature whereby a DNS server may place
additional records in the additional section of the DNS message.
These additional records are records that the client did not
explicitly request, but the server has reasonable grounds to expect
that the client might request them shortly, so including them can
save the client from having to issue additional queries.
This section recommends which additional records SHOULD be generated
to improve network efficiency, for both Unicast and Multicast DNS-SD
responses.
12.1. PTR Records
When including a DNS-SD Service Instance Enumeration or Selective
Instance Enumeration (subtype) PTR record in a response packet, the
server/responder SHOULD include the following additional records:
o The SRV record(s) named in the PTR rdata.
o The TXT record(s) named in the PTR rdata.
o All address records (type "A" and "AAAA") named in the SRV rdata.
12.2. SRV Records
When including an SRV record in a response packet, the
server/responder SHOULD include the following additional records:
o All address records (type "A" and "AAAA") named in the SRV rdata.
"""
self.additionals.append(record)
def pack(self, format_: Union[bytes, str], value: Any) -> None:
self.data.append(struct.pack(format_, value))
self.size += struct.calcsize(format_)
def write_byte(self, value: int) -> None:
"""Writes a single byte to the packet"""
self.pack(b'!c', int2byte(value))
def insert_short(self, index: int, value: int) -> None:
"""Inserts an unsigned short in a certain position in the packet"""
self.data.insert(index, struct.pack(b'!H', value))
self.size += 2
def write_short(self, value: int) -> None:
"""Writes an unsigned short to the packet"""
self.pack(b'!H', value)
def write_int(self, value: Union[float, int]) -> None:
"""Writes an unsigned integer to the packet"""
self.pack(b'!I', int(value))
def write_string(self, value: bytes) -> None:
"""Writes a string to the packet"""
assert isinstance(value, bytes)
self.data.append(value)
self.size += len(value)
def write_utf(self, s: str) -> None:
"""Writes a UTF-8 string of a given length to the packet"""
utfstr = s.encode('utf-8')
length = len(utfstr)
if length > 64:
raise NamePartTooLongException
self.write_byte(length)
self.write_string(utfstr)
def write_character_string(self, value: bytes) -> None:
assert isinstance(value, bytes)
length = len(value)
if length > 256:
raise NamePartTooLongException
self.write_byte(length)
self.write_string(value)
def write_name(self, name: str) -> None:
"""
Write names to packet
18.14. Name Compression
When generating Multicast DNS messages, implementations SHOULD use
name compression wherever possible to compress the names of resource
records, by replacing some or all of the resource record name with a
compact two-byte reference to an appearance of that data somewhere
earlier in the message [RFC1035].
"""
# split name into each label
parts = name.split('.')
if not parts[-1]:
parts.pop()
# construct each suffix
name_suffices = ['.'.join(parts[i:]) for i in range(len(parts))]
# look for an existing name or suffix
for count, sub_name in enumerate(name_suffices):
if sub_name in self.names:
break
else:
count = len(name_suffices)
# note the new names we are saving into the packet
name_length = len(name.encode('utf-8'))
for suffix in name_suffices[:count]:
self.names[suffix] = self.size + name_length - len(suffix.encode('utf-8')) - 1
# write the new names out.
for part in parts[:count]:
self.write_utf(part)
# if we wrote part of the name, create a pointer to the rest
if count != len(name_suffices):
# Found substring in packet, create pointer
index = self.names[name_suffices[count]]
self.write_byte((index >> 8) | 0xC0)
self.write_byte(index & 0xFF)
else:
# this is the end of a name
self.write_byte(0)
def write_question(self, question: DNSQuestion) -> None:
"""Writes a question to the packet"""
self.write_name(question.name)
self.write_short(question.type)
self.write_short(question.class_)
def write_record(self, record: DNSRecord, now: float) -> int:
"""Writes a record (answer, authoritative answer, additional) to
the packet"""
if self.state == self.State.finished:
return 1
start_data_length, start_size = len(self.data), self.size
self.write_name(record.name)
self.write_short(record.type)
if record.unique and self.multicast:
self.write_short(record.class_ | _CLASS_UNIQUE)
else:
self.write_short(record.class_)
if now == 0:
self.write_int(record.ttl)
else:
self.write_int(record.get_remaining_ttl(now))
index = len(self.data)
# Adjust size for the short we will write before this record
self.size += 2
record.write(self)
self.size -= 2
length = sum((len(d) for d in self.data[index:]))
# Here is the short we adjusted for
self.insert_short(index, length)
# if we go over, then rollback and quit
if self.size > _MAX_MSG_ABSOLUTE:
while len(self.data) > start_data_length:
self.data.pop()
self.size = start_size
self.state = self.State.finished
return 1
return 0
def packet(self) -> bytes:
"""Returns a string containing the packet's bytes
No further parts should be added to the packet once this
is done."""
overrun_answers, overrun_authorities, overrun_additionals = 0, 0, 0
if self.state != self.State.finished:
for question in self.questions:
self.write_question(question)
for answer, time_ in self.answers:
overrun_answers += self.write_record(answer, time_)
for authority in self.authorities:
overrun_authorities += self.write_record(authority, 0)
for additional in self.additionals:
overrun_additionals += self.write_record(additional, 0)
self.state = self.State.finished
self.insert_short(0, len(self.additionals) - overrun_additionals)
self.insert_short(0, len(self.authorities) - overrun_authorities)
self.insert_short(0, len(self.answers) - overrun_answers)
self.insert_short(0, len(self.questions))
self.insert_short(0, self.flags)
if self.multicast:
self.insert_short(0, 0)
else:
self.insert_short(0, self.id)
return b''.join(self.data)
class DNSCache:
"""A cache of DNS entries"""
def __init__(self) -> None:
self.cache = {} # type: Dict[str, List[DNSRecord]]
def add(self, entry: DNSRecord) -> None:
"""Adds an entry"""
# Insert last in list, get will return newest entry
# iteration will result in last update winning
self.cache.setdefault(entry.key, []).append(entry)
def remove(self, entry: DNSRecord) -> None:
"""Removes an entry"""
try:
list_ = self.cache[entry.key]
list_.remove(entry)
# If we remove the last entry in the list
# we remove the key from the dict in order
# to avoid leaking memory
if not list_:
del self.cache[entry.key]
except (KeyError, ValueError):
pass
def get(self, entry: DNSEntry) -> Optional[DNSRecord]:
"""Gets an entry by key. Will return None if there is no
matching entry."""
try:
list_ = self.cache[entry.key]
for cached_entry in reversed(list_):
if entry.__eq__(cached_entry):
return cached_entry
return None
except (KeyError, ValueError):
return None
def get_by_details(self, name: str, type_: int, class_: int) -> Optional[DNSRecord]:
"""Gets an entry by details. Will return None if there is
no matching entry."""
entry = DNSEntry(name, type_, class_)
return self.get(entry)
def entries_with_name(self, name: str) -> List[DNSRecord]:
"""Returns a list of entries whose key matches the name."""
try:
return self.cache[name.lower()]
except KeyError:
return []
def current_entry_with_name_and_alias(self, name: str, alias: str) -> Optional[DNSRecord]:
now = current_time_millis()
for record in reversed(self.entries_with_name(name)):
if (
record.type == _TYPE_PTR
and not record.is_expired(now)
and cast(DNSPointer, record).alias == alias
):
return record
return None
def entries(self) -> List[DNSRecord]:
"""Returns a list of all entries"""
if not self.cache:
return []
else:
# avoid size change during iteration by copying the cache
values = list(self.cache.values())
return list(itertools.chain.from_iterable(values))
class Engine(threading.Thread):
"""An engine wraps read access to sockets, allowing objects that
need to receive data from sockets to be called back when the
sockets are ready.
A reader needs a handle_read() method, which is called when the socket
it is interested in is ready for reading.
Writers are not implemented here, because we only send short
packets.
"""
def __init__(self, zc: 'Zeroconf') -> None:
threading.Thread.__init__(self, name='zeroconf-Engine')
self.daemon = True
self.zc = zc
self.readers = {} # type: Dict[socket.socket, Listener]
self.timeout = 5
self.condition = threading.Condition()
self.socketpair = socket.socketpair()
self.start()
def run(self) -> None:
while not self.zc.done:
with self.condition:
rs = list(self.readers.keys())
if len(rs) == 0:
# No sockets to manage, but we wait for the timeout
# or addition of a socket
self.condition.wait(self.timeout)
if len(rs) != 0:
try:
rs = rs + [self.socketpair[0]]
rr, wr, er = select.select(cast(Sequence[Any], rs), [], [], self.timeout)
if not self.zc.done:
for socket_ in rr:
reader = self.readers.get(socket_)
if reader:
reader.handle_read(socket_)
if self.socketpair[0] in rr:
# Clear the socket's buffer
self.socketpair[0].recv(128)
except (select.error, socket.error) as e:
# If the socket was closed by another thread, during
# shutdown, ignore it and exit
if e.args[0] not in (errno.EBADF, errno.ENOTCONN) or not self.zc.done:
raise
self.socketpair[0].close()
self.socketpair[1].close()
def _notify(self) -> None:
self.condition.notify()
try:
self.socketpair[1].send(b'x')
except socket.error:
# The socketpair may already be closed during shutdown, ignore it
if not self.zc.done:
raise
def add_reader(self, reader: 'Listener', socket_: socket.socket) -> None:
with self.condition:
self.readers[socket_] = reader
self._notify()
def del_reader(self, socket_: socket.socket) -> None:
with self.condition:
del self.readers[socket_]
self._notify()
class Listener(QuietLogger):
"""A Listener is used by this module to listen on the multicast
group to which DNS messages are sent, allowing the implementation
to cache information as it arrives.
It requires registration with an Engine object in order to have
the read() method called when a socket is available for reading."""
def __init__(self, zc: 'Zeroconf') -> None:
self.zc = zc
self.data = None # type: Optional[bytes]
def handle_read(self, socket_: socket.socket) -> None:
try:
data, (addr, port, *_v6) = socket_.recvfrom(_MAX_MSG_ABSOLUTE)
except Exception:
self.log_exception_warning()
return
log.debug('Received from %r:%r: %r ', addr, port, data)
# print(f'add={addr}, port={port},data={data}')
self.data = data
msg = DNSIncoming(data)
if not msg.valid:
pass
elif msg.is_query():
# Always multicast responses
if port == _MDNS_PORT:
self.zc.handle_query(msg, None, _MDNS_PORT)
# If it's not a multicast query, reply via unicast
# and multicast
elif port == _DNS_PORT:
self.zc.handle_query(msg, addr, port)
self.zc.handle_query(msg, None, _MDNS_PORT)
else:
self.zc.handle_response(msg)
class Reaper(threading.Thread):
"""A Reaper is used by this module to remove cache entries that
have expired."""
def __init__(self, zc: 'Zeroconf') -> None:
threading.Thread.__init__(self, name='zeroconf-Reaper')
self.daemon = True
self.zc = zc
self.start()
def run(self) -> None:
while True:
self.zc.wait(10 * 1000)
if self.zc.done:
return
now = current_time_millis()
for record in self.zc.cache.entries():
if record.is_expired(now):
self.zc.update_record(now, record)
self.zc.cache.remove(record)
class Signal:
def __init__(self) -> None:
self._handlers = [] # type: List[Callable[..., None]]
def fire(self, **kwargs: Any) -> None:
for h in list(self._handlers):
h(**kwargs)
@property
def registration_interface(self) -> 'SignalRegistrationInterface':
return SignalRegistrationInterface(self._handlers)
# NOTE: Callable quoting needed on Python 3.5.2, see
# https://github.com/jstasiak/python-zeroconf/issues/208 for details.
class SignalRegistrationInterface:
def __init__(self, handlers: List['Callable[..., None]']) -> None:
self._handlers = handlers
def register_handler(self, handler: 'Callable[..., None]') -> 'SignalRegistrationInterface':
self._handlers.append(handler)
return self
def unregister_handler(self, handler: 'Callable[..., None]') -> 'SignalRegistrationInterface':
self._handlers.remove(handler)
return self
class RecordUpdateListener:
def update_record(self, zc: 'Zeroconf', now: float, record: DNSRecord) -> None:
raise NotImplementedError()
class ServiceListener:
def add_service(self, zc: 'Zeroconf', type_: str, name: str) -> None:
raise NotImplementedError()
def remove_service(self, zc: 'Zeroconf', type_: str, name: str) -> None:
raise NotImplementedError()
def update_service(self, zc: 'Zeroconf', type_: str, name: str) -> None:
raise NotImplementedError()
[文档]class ServiceBrowser(RecordUpdateListener, threading.Thread):
"""Used to browse for a service of a specific type.
The listener object will have its add_service() and
remove_service() methods called when this browser
discovers changes in the services availability."""
def __init__(
self,
zc: 'Zeroconf',
type_: str,
# NOTE: Callable quoting needed on Python 3.5.2, see
# https://github.com/jstasiak/python-zeroconf/issues/208 for details.
handlers: Optional[Union[ServiceListener, List['Callable[..., None]']]] = None,
listener: Optional[ServiceListener] = None,
addr: Optional[str] = None,
port: int = _MDNS_PORT,
delay: int = _BROWSER_TIME,
) -> None:
"""Creates a browser for a specific type"""
assert handlers or listener, 'You need to specify at least one handler'
if not type_.endswith(service_type_name(type_, allow_underscores=True)):
raise BadTypeInNameException
threading.Thread.__init__(self, name='zeroconf-ServiceBrowser_' + type_)
self.daemon = True
self.zc = zc
self.type = type_
self.addr = addr
self.port = port
self.multicast = self.addr in (None, _MDNS_ADDR, _MDNS_ADDR6)
self.services = {} # type: Dict[str, DNSRecord]
self.next_time = current_time_millis()
self.delay = delay
self._handlers_to_call = OrderedDict() # type: OrderedDict[str, ServiceStateChange]
self._service_state_changed = Signal()
self.done = False
if hasattr(handlers, 'add_service'):
listener = cast(ServiceListener, handlers)
handlers = None
# NOTE: Callable quoting needed on Python 3.5.2, see
# https://github.com/jstasiak/python-zeroconf/issues/208 for details.
handlers = cast(List['Callable[..., None]'], handlers or [])
if listener:
def on_change(
zeroconf: 'Zeroconf', service_type: str, name: str, state_change: ServiceStateChange
) -> None:
assert listener is not None
args = (zeroconf, service_type, name)
if state_change is ServiceStateChange.Added:
listener.add_service(*args)
elif state_change is ServiceStateChange.Removed:
listener.remove_service(*args)
elif state_change is ServiceStateChange.Updated:
if hasattr(listener, 'update_service'):
listener.update_service(*args)
else:
raise NotImplementedError(state_change)
handlers.append(on_change)
for h in handlers:
self.service_state_changed.register_handler(h)
self.start()
@property
def service_state_changed(self) -> SignalRegistrationInterface:
return self._service_state_changed.registration_interface
[文档] def update_record(self, zc: 'Zeroconf', now: float, record: DNSRecord) -> None:
"""Callback invoked by Zeroconf when new information arrives.
Updates information required by browser in the Zeroconf cache.
Ensures that there is are no unecessary duplicates in the list
"""
def enqueue_callback(state_change: ServiceStateChange, name: str) -> None:
# Code to ensure we only do a single update message
# Precedence is; Added, Remove, Update
if (
state_change is ServiceStateChange.Added
or (
state_change is ServiceStateChange.Removed
and (
self._handlers_to_call.get(name) is ServiceStateChange.Updated
or self._handlers_to_call.get(name) is ServiceStateChange.Added
or self._handlers_to_call.get(name) is None
)
)
or (state_change is ServiceStateChange.Updated and name not in self._handlers_to_call)
):
self._handlers_to_call[name] = state_change
if record.type == _TYPE_PTR and record.name == self.type:
assert isinstance(record, DNSPointer)
expired = record.is_expired(now)
service_key = record.alias.lower()
try:
old_record = self.services[service_key]
except KeyError:
if not expired:
self.services[service_key] = record
enqueue_callback(ServiceStateChange.Added, record.alias)
else:
if not expired:
old_record.reset_ttl(record)
else:
del self.services[service_key]
enqueue_callback(ServiceStateChange.Removed, record.alias)
return
expires = record.get_expiration_time(75)
if expires < self.next_time:
self.next_time = expires
elif record.type == _TYPE_A or record.type == _TYPE_AAAA:
assert isinstance(record, DNSAddress)
if record.is_expired(now):
return
address_changed = False
for service in zc.cache.entries_with_name(record.name):
if isinstance(service, DNSAddress) and service.address != record.address:
address_changed = True
break
# Avoid iterating the entire DNSCache if the address has not changed
# as this is an expensive operation when there many hosts
# generating zeroconf traffic.
if not address_changed:
return
# Iterate through the DNSCache and callback any services that use this address
for service in zc.cache.entries():
if (
isinstance(service, DNSService)
and service.name.endswith(self.type)
and service.server == record.name
):
enqueue_callback(ServiceStateChange.Updated, service.name)
elif record.name.endswith(self.type):
expired = record.is_expired(now)
if not expired:
enqueue_callback(ServiceStateChange.Updated, record.name)
[文档] def cancel(self) -> None:
self.done = True
self.zc.remove_listener(self)
self.join()
[文档] def run(self) -> None:
self.zc.add_listener(self, DNSQuestion(self.type, _TYPE_PTR, _CLASS_IN))
while True:
now = current_time_millis()
if len(self._handlers_to_call) == 0 and self.next_time > now:
self.zc.wait(self.next_time - now)
if self.zc.done or self.done:
return
now = current_time_millis()
if self.next_time <= now:
out = DNSOutgoing(_FLAGS_QR_QUERY, multicast=self.multicast)
out.add_question(DNSQuestion(self.type, _TYPE_PTR, _CLASS_IN))
for record in self.services.values():
if not record.is_stale(now):
out.add_answer_at_time(record, now)
self.zc.send(out, addr=self.addr, port=self.port)
self.next_time = now + self.delay
self.delay = min(_BROWSER_BACKOFF_LIMIT * 1000, self.delay * 2)
if len(self._handlers_to_call) > 0 and not self.zc.done:
with self.zc._handlers_lock:
handler = self._handlers_to_call.popitem(False)
self._service_state_changed.fire(
zeroconf=self.zc, service_type=self.type, name=handler[0], state_change=handler[1]
)
[文档]class ServiceInfo(RecordUpdateListener):
"""Service information.
Constructor parameters are as follows:
* type_: fully qualified service type name
* name: fully qualified service name
* address: IP address as unsigned short, network byte order (deprecated, use addresses)
* port: port that the service runs on
* weight: weight of the service
* priority: priority of the service
* properties: dictionary of properties (or a bytes object holding the contents of the `text` field).
converted to str and then encoded to bytes using UTF-8. Keys with `None` values are converted to
value-less attributes.
* server: fully qualified name for service host (defaults to name)
* host_ttl: ttl used for A/SRV records
* other_ttl: ttl used for PTR/TXT records
* addresses: List of IP addresses as unsigned short (IPv4) or unsigned 128 bit number (IPv6),
network byte order
"""
text = b''
# FIXME(dtantsur): black 19.3b0 produces code that is not valid syntax on
# Python 3.5: https://github.com/python/black/issues/759
# fmt: off
def __init__(
self,
type_: str,
name: str,
address: Optional[Union[bytes, List[bytes]]] = None,
port: Optional[int] = None,
weight: int = 0,
priority: int = 0,
properties: Union[bytes, Dict] = b'',
server: Optional[str] = None,
host_ttl: int = _DNS_HOST_TTL,
other_ttl: int = _DNS_OTHER_TTL,
*,
addresses: Optional[List[bytes]] = None
) -> None:
# Accept both none, or one, but not both.
if address is not None and addresses is not None:
raise TypeError("address and addresses cannot be provided together")
if not type_.endswith(service_type_name(name, allow_underscores=True)):
raise BadTypeInNameException
self.type = type_
self.name = name
if addresses is not None:
self._addresses = addresses
elif address is not None:
warnings.warn("address is deprecated, use addresses instead", DeprecationWarning)
if isinstance(address, list):
self._addresses = address
else:
self._addresses = [address]
else:
self._addresses = []
# This results in an ugly error when registering, better check now
invalid = [a for a in self._addresses
if not isinstance(a, bytes) or len(a) not in (4, 16)]
if invalid:
raise TypeError('Addresses must be bytes, got %s. Hint: convert string addresses '
'with socket.inet_pton' % invalid)
self.port = port
self.weight = weight
self.priority = priority
if server:
self.server = server
else:
self.server = name
self._properties = {} # type: Dict
self._set_properties(properties)
self.host_ttl = host_ttl
self.other_ttl = other_ttl
# fmt: on
@property
def address(self) -> Optional[bytes]:
warnings.warn("ServiceInfo.address is deprecated, use addresses instead", DeprecationWarning)
try:
# Return the first V4 address for compatibility
return self.addresses[0]
except IndexError:
return None
@address.setter
def address(self, value: bytes) -> None:
warnings.warn("ServiceInfo.address is deprecated, use addresses instead", DeprecationWarning)
if value is None:
self._addresses = []
else:
self._addresses = [value]
@property
def addresses(self) -> List[bytes]:
"""IPv4 addresses of this service.
Only IPv4 addresses are returned for backward compatibility.
Use :meth:`addresses_by_version` or :meth:`parsed_addresses` to
include IPv6 addresses as well.
"""
return self.addresses_by_version(IPVersion.V4Only)
@addresses.setter
def addresses(self, value: List[bytes]) -> None:
"""Replace the addresses list.
This replaces all currently stored addresses, both IPv4 and IPv6.
"""
self._addresses = value
@property
def properties(self) -> Dict:
"""If properties were set in the constructor this property returns the original dictionary
of type `Dict[Union[bytes, str], Any]`.
If properties are coming from the network, after decoding a TXT record, the keys are always
bytes and the values are either bytes, if there was a value, even empty, or `None`, if there
was none. No further decoding is attempted. The type returned is `Dict[bytes, Optional[bytes]]`.
"""
return self._properties
[文档] def addresses_by_version(self, version: IPVersion) -> List[bytes]:
"""List addresses matching IP version."""
if version == IPVersion.V4Only:
return [addr for addr in self._addresses if not _is_v6_address(addr)]
elif version == IPVersion.V6Only:
return list(filter(_is_v6_address, self._addresses))
else:
return self._addresses
[文档] def parsed_addresses(self, version: IPVersion = IPVersion.All) -> List[str]:
"""List addresses in their parsed string form."""
result = self.addresses_by_version(version)
return [
socket.inet_ntop(socket.AF_INET6 if _is_v6_address(addr) else socket.AF_INET, addr)
for addr in result
]
def _set_properties(self, properties: Union[bytes, Dict]) -> None:
"""Sets properties and text of this info from a dictionary"""
if isinstance(properties, dict):
self._properties = properties
list_ = []
result = b''
for key, value in properties.items():
if isinstance(key, str):
key = key.encode('utf-8')
record = key
if value is not None:
if not isinstance(value, bytes):
value = str(value).encode('utf-8')
record += b'=' + value
list_.append(record)
for item in list_:
result = b''.join((result, int2byte(len(item)), item))
self.text = result
else:
self.text = properties
def _set_text(self, text: bytes) -> None:
"""Sets properties and text given a text field"""
self.text = text
result = {} # type: Dict
end = len(text)
index = 0
strs = []
while index < end:
length = text[index]
index += 1
strs.append(text[index: index + length])
index += length
for s in strs:
parts = s.split(b'=', 1)
try:
key, value = parts # type: Tuple[bytes, Optional[bytes]]
except ValueError:
# No equals sign at all
key = s
value = None
# Only update non-existent properties
if key and result.get(key) is None:
result[key] = value
self._properties = result
[文档] def get_name(self) -> str:
"""Name accessor"""
if self.type is not None and self.name.endswith("." + self.type):
return self.name[: len(self.name) - len(self.type) - 1]
return self.name
[文档] def update_record(self, zc: 'Zeroconf', now: float, record: Optional[DNSRecord]) -> None:
"""Updates service information from a DNS record"""
if record is not None and not record.is_expired(now):
if record.type in [_TYPE_A, _TYPE_AAAA]:
assert isinstance(record, DNSAddress)
# if record.name == self.name:
if record.name == self.server:
if record.address not in self._addresses:
self._addresses.append(record.address)
elif record.type == _TYPE_SRV:
assert isinstance(record, DNSService)
if record.name == self.name:
self.server = record.server
self.port = record.port
self.weight = record.weight
self.priority = record.priority
# self.address = None
self.update_record(zc, now, zc.cache.get_by_details(self.server, _TYPE_A, _CLASS_IN))
self.update_record(zc, now, zc.cache.get_by_details(self.server, _TYPE_AAAA, _CLASS_IN))
elif record.type == _TYPE_TXT:
assert isinstance(record, DNSText)
if record.name == self.name:
self._set_text(record.text)
[文档] def request(self, zc: 'Zeroconf', timeout: float) -> bool:
"""Returns true if the service could be discovered on the
network, and updates this object with details discovered.
"""
now = current_time_millis()
delay = _LISTENER_TIME
next_ = now + delay
last = now + timeout
record_types_for_check_cache = [(_TYPE_SRV, _CLASS_IN), (_TYPE_TXT, _CLASS_IN)]
if self.server is not None:
record_types_for_check_cache.append((_TYPE_A, _CLASS_IN))
record_types_for_check_cache.append((_TYPE_AAAA, _CLASS_IN))
for record_type in record_types_for_check_cache:
cached = zc.cache.get_by_details(self.name, *record_type)
if cached:
self.update_record(zc, now, cached)
if self.server is not None and self.text is not None and self._addresses:
return True
try:
zc.add_listener(self, DNSQuestion(self.name, _TYPE_ANY, _CLASS_IN))
while self.server is None or self.text is None or not self._addresses:
if last <= now:
return False
if next_ <= now:
out = DNSOutgoing(_FLAGS_QR_QUERY)
out.add_question(DNSQuestion(self.name, _TYPE_SRV, _CLASS_IN))
out.add_answer_at_time(zc.cache.get_by_details(self.name, _TYPE_SRV, _CLASS_IN), now)
out.add_question(DNSQuestion(self.name, _TYPE_TXT, _CLASS_IN))
out.add_answer_at_time(zc.cache.get_by_details(self.name, _TYPE_TXT, _CLASS_IN), now)
if self.server is not None:
out.add_question(DNSQuestion(self.server, _TYPE_A, _CLASS_IN))
out.add_answer_at_time(zc.cache.get_by_details(self.server, _TYPE_A, _CLASS_IN), now)
out.add_question(DNSQuestion(self.server, _TYPE_AAAA, _CLASS_IN))
out.add_answer_at_time(
zc.cache.get_by_details(self.server, _TYPE_AAAA, _CLASS_IN), now
)
zc.send(out)
next_ = now + delay
delay *= 2
zc.wait(min(next_, last) - now)
now = current_time_millis()
finally:
zc.remove_listener(self)
return True
def __eq__(self, other: object) -> bool:
"""Tests equality of service name"""
return isinstance(other, ServiceInfo) and other.name == self.name
def __ne__(self, other: object) -> bool:
"""Non-equality test"""
return not self.__eq__(other)
def __repr__(self) -> str:
"""String representation"""
return '%s(%s)' % (
type(self).__name__,
', '.join(
'%s=%r' % (name, getattr(self, name))
for name in (
'type',
'name',
'addresses',
'port',
'weight',
'priority',
'server',
'properties',
)
),
)
class ZeroconfServiceTypes(ServiceListener):
"""
Return all of the advertised services on any local networks
"""
def __init__(self) -> None:
self.found_services = set() # type: Set[str]
def add_service(self, zc: 'Zeroconf', type_: str, name: str) -> None:
self.found_services.add(name)
def remove_service(self, zc: 'Zeroconf', type_: str, name: str) -> None:
pass
@classmethod
def find(
cls,
zc: Optional['Zeroconf'] = None,
timeout: Union[int, float] = 5,
interfaces: InterfacesType = InterfaceChoice.All,
ip_version: Optional[IPVersion] = None,
) -> Tuple[str, ...]:
"""
Return all of the advertised services on any local networks.
:param zc: Zeroconf() instance. Pass in if already have an
instance running or if non-default interfaces are needed
:param timeout: seconds to wait for any responses
:param interfaces: interfaces to listen on.
:param ip_version: IP protocol version to use.
:return: tuple of service type strings
"""
local_zc = zc or Zeroconf(interfaces=interfaces, ip_version=ip_version)
listener = cls()
browser = ServiceBrowser(local_zc, '_services._dns-sd._udp.local.', listener=listener)
# wait for responses
time.sleep(timeout)
# close down anything we opened
if zc is None:
local_zc.close()
else:
browser.cancel()
return tuple(sorted(listener.found_services))
def get_all_addresses() -> List[str]:
return list(set(addr.ip for iface in ifaddr.get_adapters() for addr in iface.ips if addr.is_IPv4))
def get_all_addresses_v6() -> List[int]:
# IPv6 multicast uses positive indexes for interfaces
try:
nameindex = socket.if_nameindex
except AttributeError:
# Requires Python 3.8 on Windows. Fall back to Default.
QuietLogger.log_warning_once(
'if_nameindex is not available, falling back to using the default IPv6 interface'
)
return [0]
return [tpl[0] for tpl in nameindex()]
def ip_to_index(adapters: List[Any], ip: str) -> int:
if os.name != 'posix':
# Adapter names that ifaddr reports are not compatible with what if_nametoindex expects on Windows.
# We need https://github.com/pydron/ifaddr/pull/21 but it seems stuck on review.
raise RuntimeError('Converting from IP addresses to indexes is not supported on non-POSIX systems')
ipaddr = ipaddress.ip_address(ip)
for adapter in adapters:
for adapter_ip in adapter.ips:
# IPv6 addresses are represented as tuples
if isinstance(adapter_ip.ip, tuple) and ipaddress.ip_address(adapter_ip.ip[0]) == ipaddr:
return socket.if_nametoindex(adapter.name)
raise RuntimeError('No adapter found for IP address %s' % ip)
def ip6_addresses_to_indexes(interfaces: List[Union[str, int]]) -> List[int]:
"""Convert IPv6 interface addresses to interface indexes.
IPv4 addresses are ignored. The conversion currently only works on POSIX
systems.
:param interfaces: List of IP addresses and indexes.
:returns: List of indexes.
"""
result = []
adapters = ifaddr.get_adapters()
for iface in interfaces:
if isinstance(iface, int):
result.append(iface)
elif isinstance(iface, str) and ipaddress.ip_address(iface).version == 6:
result.append(ip_to_index(adapters, iface))
return result
def normalize_interface_choice(
choice: InterfacesType, ip_version: IPVersion = IPVersion.V4Only
) -> List[Union[str, int]]:
"""Convert the interfaces choice into internal representation.
:param choice: `InterfaceChoice` or list of interface addresses or indexes (IPv6 only).
:param ip_address: IP version to use (ignored if `choice` is a list).
:returns: List of IP addresses (for IPv4) and indexes (for IPv6).
"""
result = [] # type: List[Union[str, int]]
if choice is InterfaceChoice.Default:
if ip_version != IPVersion.V4Only:
# IPv6 multicast uses interface 0 to mean the default
result.append(0)
if ip_version != IPVersion.V6Only:
result.append('0.0.0.0')
elif choice is InterfaceChoice.All:
if ip_version != IPVersion.V4Only:
result.extend(get_all_addresses_v6())
if ip_version != IPVersion.V6Only:
result.extend(get_all_addresses())
if not result:
raise RuntimeError(
'No interfaces to listen on, check that any interfaces have IP version %s' % ip_version
)
elif isinstance(choice, list):
# First, take IPv4 addresses.
result = [i for i in choice if isinstance(i, str) and ipaddress.ip_address(i).version == 4]
# Unlike IP_ADD_MEMBERSHIP, IPV6_JOIN_GROUP requires interface indexes.
result += ip6_addresses_to_indexes(choice)
else:
raise TypeError("choice must be a list or InterfaceChoice, got %r" % choice)
return result
def new_socket(
port: int = _MDNS_PORT, ip_version: IPVersion = IPVersion.V4Only, apple_p2p: bool = False
) -> socket.socket:
if ip_version == IPVersion.V4Only:
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
else:
s = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
if ip_version == IPVersion.All:
# make V6 sockets work for both V4 and V6 (required for Windows)
try:
s.setsockopt(_IPPROTO_IPV6, socket.IPV6_V6ONLY, False)
except OSError:
log.error('Support for dual V4-V6 sockets is not present, use IPVersion.V4 or IPVersion.V6')
raise
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
# SO_REUSEADDR should be equivalent to SO_REUSEPORT for
# multicast UDP sockets (p 731, "TCP/IP Illustrated,
# Volume 2"), but some BSD-derived systems require
# SO_REUSEPORT to be specified explicitly. Also, not all
# versions of Python have SO_REUSEPORT available.
# Catch OSError and socket.error for kernel versions <3.9 because lacking
# SO_REUSEPORT support.
try:
reuseport = socket.SO_REUSEPORT
except AttributeError:
pass
else:
try:
s.setsockopt(socket.SOL_SOCKET, reuseport, 1)
except (OSError, socket.error) as err:
# OSError on python 3, socket.error on python 2
if not err.errno == errno.ENOPROTOOPT:
raise
if port is _MDNS_PORT:
ttl = struct.pack(b'B', 255)
loop = struct.pack(b'B', 1)
if ip_version != IPVersion.V6Only:
# OpenBSD needs the ttl and loop values for the IP_MULTICAST_TTL and
# IP_MULTICAST_LOOP socket options as an unsigned char.
s.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, ttl)
s.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_LOOP, loop)
if ip_version != IPVersion.V4Only:
# However, char doesn't work here (at least on Linux)
s.setsockopt(_IPPROTO_IPV6, socket.IPV6_MULTICAST_HOPS, 255)
s.setsockopt(_IPPROTO_IPV6, socket.IPV6_MULTICAST_LOOP, True)
if apple_p2p:
# SO_RECV_ANYIF = 0x1104
# https://opensource.apple.com/source/xnu/xnu-4570.41.2/bsd/sys/socket.h
s.setsockopt(socket.SOL_SOCKET, 0x1104, 1)
s.bind(('', port))
return s
def add_multicast_member(
listen_socket: socket.socket, interface: Union[str, int], apple_p2p: bool = False
) -> Optional[socket.socket]:
# This is based on assumptions in normalize_interface_choice
is_v6 = isinstance(interface, int)
log.debug('Adding %r to multicast group', interface)
try:
if is_v6:
iface_bin = struct.pack('@I', cast(int, interface))
_value = _MDNS_ADDR6_BYTES + iface_bin
listen_socket.setsockopt(_IPPROTO_IPV6, socket.IPV6_JOIN_GROUP, _value)
else:
_value = _MDNS_ADDR_BYTES + socket.inet_aton(cast(str, interface))
listen_socket.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, _value)
except socket.error as e:
_errno = get_errno(e)
if _errno == errno.EADDRINUSE:
log.info(
'Address in use when adding %s to multicast group, '
'it is expected to happen on some systems',
interface,
)
return None
elif _errno == errno.EADDRNOTAVAIL:
log.info(
'Address not available when adding %s to multicast '
'group, it is expected to happen on some systems',
interface,
)
return None
elif _errno == errno.EINVAL:
log.info('Interface of %s does not support multicast, ' 'it is expected in WSL', interface)
return None
else:
raise
respond_socket = new_socket(
ip_version=(IPVersion.V6Only if is_v6 else IPVersion.V4Only), apple_p2p=apple_p2p
)
log.debug('Configuring %s with multicast interface %s', respond_socket, interface)
if is_v6:
respond_socket.setsockopt(_IPPROTO_IPV6, socket.IPV6_MULTICAST_IF, iface_bin)
else:
respond_socket.setsockopt(
socket.IPPROTO_IP, socket.IP_MULTICAST_IF, socket.inet_aton(cast(str, interface))
)
return respond_socket
def create_sockets(
interfaces: InterfacesType = InterfaceChoice.All,
unicast: bool = False,
ip_version: IPVersion = IPVersion.V4Only,
apple_p2p: bool = False,
) -> Tuple[Optional[socket.socket], List[socket.socket]]:
if unicast:
listen_socket = None
else:
listen_socket = new_socket(ip_version=ip_version, apple_p2p=apple_p2p)
interfaces = normalize_interface_choice(interfaces, ip_version)
respond_sockets = []
for i in interfaces:
if not unicast:
respond_socket = add_multicast_member(cast(socket.socket, listen_socket), i, apple_p2p=apple_p2p)
else:
respond_socket = new_socket(port=0, ip_version=ip_version, apple_p2p=apple_p2p)
if respond_socket is not None:
respond_sockets.append(respond_socket)
return listen_socket, respond_sockets
def get_errno(e: Exception) -> int:
assert isinstance(e, socket.error)
return cast(int, e.args[0])
def can_send_to(sock: socket.socket, address: str) -> bool:
addr = ipaddress.ip_address(address)
return cast(bool, addr.version == 6 if sock.family == socket.AF_INET6 else addr.version == 4)
[文档]class Zeroconf(QuietLogger):
"""Implementation of Zeroconf Multicast DNS Service Discovery
Supports registration, unregistration, queries and browsing.
"""
def __init__(
self,
interfaces: InterfacesType = InterfaceChoice.All,
unicast: bool = False,
ip_version: Optional[IPVersion] = None,
apple_p2p: bool = False,
) -> None:
"""Creates an instance of the Zeroconf class, establishing
multicast communications, listening and reaping threads.
:param interfaces: :class:`InterfaceChoice` or a list of IP addresses
(IPv4 and IPv6) and interface indexes (IPv6 only).
IPv6 notes for non-POSIX systems:
* IPv6 addresses are not supported, use indexes instead.
* `InterfaceChoice.All` is an alias for `InterfaceChoice.Default`
on Python versions before 3.8.
Also listening on loopback (``::1``) doesn't work, use a real address.
:param ip_version: IP versions to support. If `choice` is a list, the default is detected
from it. Otherwise defaults to V4 only for backward compatibility.
:param apple_p2p: use AWDL interface (only macOS)
"""
if ip_version is None and isinstance(interfaces, list):
has_v6 = any(
isinstance(i, int) or (isinstance(i, str) and ipaddress.ip_address(i).version == 6)
for i in interfaces
)
has_v4 = any(isinstance(i, str) and ipaddress.ip_address(i).version == 4 for i in interfaces)
if has_v4 and has_v6:
ip_version = IPVersion.All
elif has_v6:
ip_version = IPVersion.V6Only
if ip_version is None:
ip_version = IPVersion.V4Only
# hook for threads
self._GLOBAL_DONE = False
self.unicast = unicast
if apple_p2p and not platform.system() == 'Darwin':
raise RuntimeError('Option `apple_p2p` is not supported on non-Apple platforms.')
self._listen_socket, self._respond_sockets = create_sockets(
interfaces, unicast, ip_version, apple_p2p=apple_p2p
)
self.listeners = [] # type: List[RecordUpdateListener]
self.browsers = {} # type: Dict[ServiceListener, ServiceBrowser]
self.services = {} # type: Dict[str, ServiceInfo]
self.servicetypes = {} # type: Dict[str, int]
self.cache = DNSCache()
self.condition = threading.Condition()
self.engine = Engine(self)
self.listener = Listener(self)
if not unicast:
self.engine.add_reader(self.listener, cast(socket.socket, self._listen_socket))
else:
for s in self._respond_sockets:
self.engine.add_reader(self.listener, s)
self.reaper = Reaper(self)
self.debug = None # type: Optional[DNSOutgoing]
self._handlers_lock = threading.Lock() # ensure we process a full message in one go
@property
def done(self) -> bool:
return self._GLOBAL_DONE
[文档] def wait(self, timeout: float) -> None:
"""Calling thread waits for a given number of milliseconds or
until notified."""
with self.condition:
self.condition.wait(timeout / 1000.0)
[文档] def notify_all(self) -> None:
"""Notifies all waiting threads"""
with self.condition:
self.condition.notify_all()
[文档] def get_service_info(self, type_: str, name: str, timeout: int = 3000) -> Optional[ServiceInfo]:
"""Returns network's service information for a particular
name and type, or None if no service matches by the timeout,
which defaults to 3 seconds."""
info = ServiceInfo(type_, name)
if info.request(self, timeout):
return info
return None
[文档] def add_service_listener(self, type_: str, listener: ServiceListener) -> None:
"""Adds a listener for a particular service type. This object
will then have its add_service and remove_service methods called when
services of that type become available and unavailable."""
self.remove_service_listener(listener)
self.browsers[listener] = ServiceBrowser(self, type_, listener)
[文档] def remove_service_listener(self, listener: ServiceListener) -> None:
"""Removes a listener from the set that is currently listening."""
if listener in self.browsers:
self.browsers[listener].cancel()
del self.browsers[listener]
[文档] def remove_all_service_listeners(self) -> None:
"""Removes a listener from the set that is currently listening."""
for listener in [k for k in self.browsers]:
self.remove_service_listener(listener)
[文档] def register_service(
self,
info: ServiceInfo,
ttl: Optional[int] = None,
allow_name_change: bool = False,
cooperating_responders: bool = False,
) -> None:
"""Registers service information to the network with a default TTL.
Zeroconf will then respond to requests for information for that
service. The name of the service may be changed if needed to make
it unique on the network. Additionally multiple cooperating responders
can register the same service on the network for resilience
(if you want this behavior set `cooperating_responders` to `True`)."""
if ttl is not None:
# ttl argument is used to maintain backward compatibility
# Setting TTLs via ServiceInfo is preferred
info.host_ttl = ttl
info.other_ttl = ttl
self.check_service(info, allow_name_change, cooperating_responders)
self.services[info.name.lower()] = info
if info.type in self.servicetypes:
self.servicetypes[info.type] += 1
else:
self.servicetypes[info.type] = 1
self._broadcast_service(info)
[文档] def update_service(self, info: ServiceInfo) -> None:
"""Registers service information to the network with a default TTL.
Zeroconf will then respond to requests for information for that
service."""
assert self.services[info.name.lower()] is not None
self.services[info.name.lower()] = info
self._broadcast_service(info)
def _broadcast_service(self, info: ServiceInfo) -> None:
now = current_time_millis()
next_time = now
i = 0
while i < 3:
if now < next_time:
self.wait(next_time - now)
now = current_time_millis()
continue
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA)
out.add_answer_at_time(DNSPointer(info.type, _TYPE_PTR, _CLASS_IN, info.other_ttl, info.name), 0)
out.add_answer_at_time(
DNSService(
info.name,
_TYPE_SRV,
_CLASS_IN | _CLASS_UNIQUE,
info.host_ttl,
info.priority,
info.weight,
cast(int, info.port),
info.server,
),
0,
)
out.add_answer_at_time(
DNSText(info.name, _TYPE_TXT, _CLASS_IN | _CLASS_UNIQUE, info.other_ttl, info.text), 0
)
for address in info.addresses_by_version(IPVersion.All):
type_ = _TYPE_AAAA if _is_v6_address(address) else _TYPE_A
out.add_answer_at_time(
DNSAddress(info.server, type_, _CLASS_IN | _CLASS_UNIQUE, info.host_ttl, address), 0
)
self.send(out)
i += 1
next_time += _REGISTER_TIME
[文档] def unregister_service(self, info: ServiceInfo) -> None:
"""Unregister a service."""
try:
del self.services[info.name.lower()]
if self.servicetypes[info.type] > 1:
self.servicetypes[info.type] -= 1
else:
del self.servicetypes[info.type]
except Exception as e: # TODO stop catching all Exceptions
log.exception('Unknown error, possibly benign: %r', e)
now = current_time_millis()
next_time = now
i = 0
while i < 3:
if now < next_time:
self.wait(next_time - now)
now = current_time_millis()
continue
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA)
out.add_answer_at_time(DNSPointer(info.type, _TYPE_PTR, _CLASS_IN, 0, info.name), 0)
out.add_answer_at_time(
DNSService(
info.name,
_TYPE_SRV,
_CLASS_IN | _CLASS_UNIQUE,
0,
info.priority,
info.weight,
cast(int, info.port),
info.name,
),
0,
)
out.add_answer_at_time(DNSText(info.name, _TYPE_TXT, _CLASS_IN | _CLASS_UNIQUE, 0, info.text), 0)
for address in info.addresses_by_version(IPVersion.All):
type_ = _TYPE_AAAA if _is_v6_address(address) else _TYPE_A
out.add_answer_at_time(
DNSAddress(info.server, type_, _CLASS_IN | _CLASS_UNIQUE, 0, address), 0
)
self.send(out)
i += 1
next_time += _UNREGISTER_TIME
[文档] def unregister_all_services(self) -> None:
"""Unregister all registered services."""
if len(self.services) > 0:
now = current_time_millis()
next_time = now
i = 0
while i < 3:
if now < next_time:
self.wait(next_time - now)
now = current_time_millis()
continue
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA)
for info in self.services.values():
out.add_answer_at_time(DNSPointer(info.type, _TYPE_PTR, _CLASS_IN, 0, info.name), 0)
out.add_answer_at_time(
DNSService(
info.name,
_TYPE_SRV,
_CLASS_IN | _CLASS_UNIQUE,
0,
info.priority,
info.weight,
cast(int, info.port),
info.server,
),
0,
)
out.add_answer_at_time(
DNSText(info.name, _TYPE_TXT, _CLASS_IN | _CLASS_UNIQUE, 0, info.text), 0
)
for address in info.addresses_by_version(IPVersion.All):
type_ = _TYPE_AAAA if _is_v6_address(address) else _TYPE_A
out.add_answer_at_time(
DNSAddress(info.server, type_, _CLASS_IN | _CLASS_UNIQUE, 0, address), 0
)
self.send(out)
i += 1
next_time += _UNREGISTER_TIME
[文档] def check_service(
self, info: ServiceInfo, allow_name_change: bool, cooperating_responders: bool = False
) -> None:
"""Checks the network for a unique service name, modifying the
ServiceInfo passed in if it is not unique."""
# This is kind of funky because of the subtype based tests
# need to make subtypes a first class citizen
service_name = service_type_name(info.name)
if not info.type.endswith(service_name):
raise BadTypeInNameException
instance_name = info.name[: -len(service_name) - 1]
next_instance_number = 2
now = current_time_millis()
next_time = now
i = 0
while i < 3:
if not cooperating_responders:
# check for a name conflict
while self.cache.current_entry_with_name_and_alias(info.type, info.name):
if not allow_name_change:
raise NonUniqueNameException
# change the name and look for a conflict
info.name = '%s-%s.%s' % (instance_name, next_instance_number, info.type)
next_instance_number += 1
service_type_name(info.name)
next_time = now
i = 0
if now < next_time:
self.wait(next_time - now)
now = current_time_millis()
continue
out = DNSOutgoing(_FLAGS_QR_QUERY | _FLAGS_AA)
self.debug = out
out.add_question(DNSQuestion(info.type, _TYPE_PTR, _CLASS_IN))
out.add_authorative_answer(DNSPointer(info.type, _TYPE_PTR, _CLASS_IN, info.other_ttl, info.name))
self.send(out)
i += 1
next_time += _CHECK_TIME
[文档] def add_listener(self, listener: RecordUpdateListener, question: Optional[DNSQuestion]) -> None:
"""Adds a listener for a given question. The listener will have
its update_record method called when information is available to
answer the question."""
now = current_time_millis()
self.listeners.append(listener)
if question is not None:
for record in self.cache.entries_with_name(question.name):
if question.answered_by(record) and not record.is_expired(now):
listener.update_record(self, now, record)
self.notify_all()
[文档] def remove_listener(self, listener: RecordUpdateListener) -> None:
"""Removes a listener."""
try:
self.listeners.remove(listener)
self.notify_all()
except Exception as e: # TODO stop catching all Exceptions
log.exception('Unknown error, possibly benign: %r', e)
[文档] def update_record(self, now: float, rec: DNSRecord) -> None:
"""Used to notify listeners of new information that has updated
a record."""
for listener in self.listeners:
listener.update_record(self, now, rec)
self.notify_all()
[文档] def handle_response(self, msg: DNSIncoming) -> None:
"""Deal with incoming response packets. All answers
are held in the cache, and listeners are notified."""
if not hasattr(self, "_handlers_lock"):
log.warning("_handlers_lock no init completed.")
return None
with self._handlers_lock:
now = current_time_millis()
for record in msg.answers:
updated = True
if record.unique: # https://tools.ietf.org/html/rfc6762#section-10.2
# Since the cache format is keyed on the lower case record name
# we can avoid iterating everything in the cache and
# only look though entries for the specific name.
# entries_with_name will take care of converting to lowercase
#
# We make a copy of the list that entries_with_name returns
# since we cannot iterate over something we might remove
for entry in self.cache.entries_with_name(record.name).copy():
if entry == record:
updated = False
# Check the time first because it is far cheaper
# than the __eq__
if (record.created - entry.created > 1000) and DNSEntry.__eq__(entry, record):
self.cache.remove(entry)
expired = record.is_expired(now)
maybe_entry = self.cache.get(record)
if not expired:
if maybe_entry is not None:
maybe_entry.reset_ttl(record)
else:
self.cache.add(record)
if updated:
self.update_record(now, record)
else:
if maybe_entry is not None:
self.update_record(now, record)
self.cache.remove(maybe_entry)
[文档] def handle_query(self, msg: DNSIncoming, addr: Optional[str], port: int) -> None:
"""Deal with incoming query packets. Provides a response if
possible."""
out = None
# Support unicast client responses
#
if port != _MDNS_PORT:
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA, multicast=False)
for question in msg.questions:
out.add_question(question)
for question in msg.questions:
if question.type == _TYPE_PTR:
if question.name == "_services._dns-sd._udp.local.":
for stype in self.servicetypes.keys():
if out is None:
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA)
out.add_answer(
msg,
DNSPointer(
"_services._dns-sd._udp.local.", _TYPE_PTR, _CLASS_IN, _DNS_OTHER_TTL, stype
),
)
for service in self.services.values():
if question.name == service.type:
if out is None:
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA)
out.add_answer(
msg,
DNSPointer(service.type, _TYPE_PTR, _CLASS_IN, service.other_ttl, service.name),
)
# Add recommended additional answers according to
# https://tools.ietf.org/html/rfc6763#section-12.1.
out.add_additional_answer(
DNSService(
service.name,
_TYPE_SRV,
_CLASS_IN | _CLASS_UNIQUE,
service.host_ttl,
service.priority,
service.weight,
cast(int, service.port),
service.server,
)
)
out.add_additional_answer(
DNSText(
service.name,
_TYPE_TXT,
_CLASS_IN | _CLASS_UNIQUE,
service.other_ttl,
service.text,
)
)
for address in service.addresses_by_version(IPVersion.All):
type_ = _TYPE_AAAA if _is_v6_address(address) else _TYPE_A
out.add_additional_answer(
DNSAddress(
service.server,
type_,
_CLASS_IN | _CLASS_UNIQUE,
service.host_ttl,
address,
)
)
else:
try:
if out is None:
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA)
# Answer A record queries for any service addresses we know
if question.type in (_TYPE_A, _TYPE_ANY):
for service in self.services.values():
if service.server == question.name.lower():
for address in service.addresses_by_version(IPVersion.All):
type_ = _TYPE_AAAA if _is_v6_address(address) else _TYPE_A
out.add_answer(
msg,
DNSAddress(
question.name,
type_,
_CLASS_IN | _CLASS_UNIQUE,
service.host_ttl,
address,
),
)
name_to_find = question.name.lower()
if name_to_find not in self.services:
continue
service = self.services[name_to_find]
if question.type in (_TYPE_SRV, _TYPE_ANY):
out.add_answer(
msg,
DNSService(
question.name,
_TYPE_SRV,
_CLASS_IN | _CLASS_UNIQUE,
service.host_ttl,
service.priority,
service.weight,
cast(int, service.port),
service.server,
),
)
if question.type in (_TYPE_TXT, _TYPE_ANY):
out.add_answer(
msg,
DNSText(
question.name,
_TYPE_TXT,
_CLASS_IN | _CLASS_UNIQUE,
service.other_ttl,
service.text,
),
)
if question.type == _TYPE_SRV:
for address in service.addresses_by_version(IPVersion.All):
type_ = _TYPE_AAAA if _is_v6_address(address) else _TYPE_A
out.add_additional_answer(
DNSAddress(
service.server,
type_,
_CLASS_IN | _CLASS_UNIQUE,
service.host_ttl,
address,
)
)
except Exception: # TODO stop catching all Exceptions
self.log_exception_warning()
if out is not None and out.answers:
out.id = msg.id
self.send(out, addr, port)
[文档] def send(self, out: DNSOutgoing, addr: Optional[str] = None, port: int = _MDNS_PORT) -> None:
"""Sends an outgoing packet."""
packet = out.packet()
if len(packet) > _MAX_MSG_ABSOLUTE:
self.log_warning_once("Dropping %r over-sized packet (%d bytes) %r", out, len(packet), packet)
return
log.debug('Sending %r (%d bytes) as %r...', out, len(packet), packet)
for s in self._respond_sockets:
if self._GLOBAL_DONE:
return
try:
if addr is None:
real_addr = _MDNS_ADDR6 if s.family == socket.AF_INET6 else _MDNS_ADDR
elif not can_send_to(s, addr):
continue
else:
real_addr = addr
bytes_sent = s.sendto(packet, 0, (real_addr, port))
except Exception as exc: # TODO stop catching all Exceptions
if (
isinstance(exc, OSError)
and exc.errno == errno.ENETUNREACH
and s.family == socket.AF_INET6
):
# with IPv6 we don't have a reliable way to determine if an interface actually has IPv6
# support, so we have to try and ignore errors.
continue
# on send errors, log the exception and keep going
self.log_exception_warning()
else:
if bytes_sent != len(packet):
self.log_warning_once('!!! sent %d out of %d bytes to %r' % (bytes_sent, len(packet), s))
[文档] def close(self) -> None:
"""Ends the background threads, and prevent this instance from
servicing further queries."""
if not self._GLOBAL_DONE:
# remove service listeners
self.remove_all_service_listeners()
self.unregister_all_services()
self._GLOBAL_DONE = True
# shutdown recv socket and thread
if not self.unicast:
self.engine.del_reader(cast(socket.socket, self._listen_socket))
cast(socket.socket, self._listen_socket).close()
else:
for s in self._respond_sockets:
self.engine.del_reader(s)
self.engine.join()
# shutdown the rest
self.notify_all()
self.reaper.join()
for s in self._respond_sockets:
s.close()