177 lines
6.8 KiB
Python
177 lines
6.8 KiB
Python
""" Multicast DNS Service Discovery for Python, v0.14-wmcbrine
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Copyright 2003 Paul Scott-Murphy, 2014 William McBrine
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This module provides a framework for the use of DNS Service Discovery
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using IP multicast.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
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USA
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"""
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from functools import lru_cache
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from typing import Set
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from .._exceptions import BadTypeInNameException
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from ..const import (
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_HAS_A_TO_Z,
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_HAS_ASCII_CONTROL_CHARS,
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_HAS_ONLY_A_TO_Z_NUM_HYPHEN,
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_HAS_ONLY_A_TO_Z_NUM_HYPHEN_UNDERSCORE,
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_LOCAL_TRAILER,
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_NONTCP_PROTOCOL_LOCAL_TRAILER,
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_TCP_PROTOCOL_LOCAL_TRAILER,
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)
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@lru_cache(maxsize=512)
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def service_type_name(type_: str, *, strict: bool = True) -> str: # pylint: disable=too-many-branches
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"""
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Validate a fully qualified service name, instance or subtype. [rfc6763]
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Returns fully qualified service name.
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Domain names used by mDNS-SD take the following forms:
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<sn> . <_tcp|_udp> . local.
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<Instance> . <sn> . <_tcp|_udp> . local.
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<sub>._sub . <sn> . <_tcp|_udp> . local.
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1) must end with 'local.'
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This is true because we are implementing mDNS and since the 'm' means
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multi-cast, the 'local.' domain is mandatory.
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2) local is preceded with either '_udp.' or '_tcp.' unless
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strict is False
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3) service name <sn> precedes <_tcp|_udp> unless
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strict is False
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The rules for Service Names [RFC6335] state that they may be no more
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than fifteen characters long (not counting the mandatory underscore),
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consisting of only letters, digits, and hyphens, must begin and end
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with a letter or digit, must not contain consecutive hyphens, and
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must contain at least one letter.
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The instance name <Instance> and sub type <sub> may be up to 63 bytes.
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The portion of the Service Instance Name is a user-
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friendly name consisting of arbitrary Net-Unicode text [RFC5198]. It
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MUST NOT contain ASCII control characters (byte values 0x00-0x1F and
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0x7F) [RFC20] but otherwise is allowed to contain any characters,
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without restriction, including spaces, uppercase, lowercase,
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punctuation -- including dots -- accented characters, non-Roman text,
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and anything else that may be represented using Net-Unicode.
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:param type_: Type, SubType or service name to validate
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:return: fully qualified service name (eg: _http._tcp.local.)
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"""
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if len(type_) > 256:
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# https://datatracker.ietf.org/doc/html/rfc6763#section-7.2
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raise BadTypeInNameException("Full name (%s) must be > 256 bytes" % type_)
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if type_.endswith((_TCP_PROTOCOL_LOCAL_TRAILER, _NONTCP_PROTOCOL_LOCAL_TRAILER)):
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remaining = type_[: -len(_TCP_PROTOCOL_LOCAL_TRAILER)].split('.')
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trailer = type_[-len(_TCP_PROTOCOL_LOCAL_TRAILER) :]
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has_protocol = True
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elif strict:
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raise BadTypeInNameException(
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"Type '%s' must end with '%s' or '%s'"
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% (type_, _TCP_PROTOCOL_LOCAL_TRAILER, _NONTCP_PROTOCOL_LOCAL_TRAILER)
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)
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elif type_.endswith(_LOCAL_TRAILER):
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remaining = type_[: -len(_LOCAL_TRAILER)].split('.')
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trailer = type_[-len(_LOCAL_TRAILER) + 1 :]
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has_protocol = False
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else:
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raise BadTypeInNameException(f"Type '{type_}' must end with '{_LOCAL_TRAILER}'")
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if strict or has_protocol:
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service_name = remaining.pop()
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if not service_name:
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raise BadTypeInNameException("No Service name found")
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if len(remaining) == 1 and len(remaining[0]) == 0:
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raise BadTypeInNameException("Type '%s' must not start with '.'" % type_)
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if service_name[0] != '_':
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raise BadTypeInNameException("Service name (%s) must start with '_'" % service_name)
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test_service_name = service_name[1:]
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if strict and len(test_service_name) > 15:
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# https://datatracker.ietf.org/doc/html/rfc6763#section-7.2
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raise BadTypeInNameException("Service name (%s) must be <= 15 bytes" % test_service_name)
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if '--' in test_service_name:
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raise BadTypeInNameException("Service name (%s) must not contain '--'" % test_service_name)
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if '-' in (test_service_name[0], test_service_name[-1]):
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raise BadTypeInNameException(
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"Service name (%s) may not start or end with '-'" % test_service_name
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)
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if not _HAS_A_TO_Z.search(test_service_name):
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raise BadTypeInNameException(
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"Service name (%s) must contain at least one letter (eg: 'A-Z')" % test_service_name
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)
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allowed_characters_re = (
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_HAS_ONLY_A_TO_Z_NUM_HYPHEN if strict else _HAS_ONLY_A_TO_Z_NUM_HYPHEN_UNDERSCORE
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)
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if not allowed_characters_re.search(test_service_name):
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raise BadTypeInNameException(
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"Service name (%s) must contain only these characters: "
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"A-Z, a-z, 0-9, hyphen ('-')%s" % (test_service_name, "" if strict else ", underscore ('_')")
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)
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else:
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service_name = ''
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if remaining and remaining[-1] == '_sub':
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remaining.pop()
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if len(remaining) == 0 or len(remaining[0]) == 0:
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raise BadTypeInNameException("_sub requires a subtype name")
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if len(remaining) > 1:
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remaining = ['.'.join(remaining)]
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if remaining:
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length = len(remaining[0].encode('utf-8'))
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if length > 63:
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raise BadTypeInNameException("Too long: '%s'" % remaining[0])
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if _HAS_ASCII_CONTROL_CHARS.search(remaining[0]):
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raise BadTypeInNameException(
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"Ascii control character 0x00-0x1F and 0x7F illegal in '%s'" % remaining[0]
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)
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return service_name + trailer
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def possible_types(name: str) -> Set[str]:
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"""Build a set of all possible types from a fully qualified name."""
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labels = name.split('.')
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label_count = len(labels)
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types = set()
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for count in range(label_count):
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parts = labels[label_count - count - 4 :]
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if not parts[0].startswith('_'):
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break
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types.add('.'.join(parts))
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return types
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cached_possible_types = lru_cache(maxsize=256)(possible_types)
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