"""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 """ from __future__ import annotations from functools import lru_cache from .._exceptions import BadTypeInNameException from ..const import ( _HAS_A_TO_Z, _HAS_ASCII_CONTROL_CHARS, _HAS_ONLY_A_TO_Z_NUM_HYPHEN, _HAS_ONLY_A_TO_Z_NUM_HYPHEN_UNDERSCORE, _LOCAL_TRAILER, _NONTCP_PROTOCOL_LOCAL_TRAILER, _TCP_PROTOCOL_LOCAL_TRAILER, ) @lru_cache(maxsize=512) def service_type_name(type_: str, *, strict: bool = True) -> str: # pylint: disable=too-many-branches """ 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: . <_tcp|_udp> . local. . . <_tcp|_udp> . local. ._sub . . <_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.' unless strict is False 3) service name precedes <_tcp|_udp> unless strict is False 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 and sub type 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 len(type_) > 256: # https://datatracker.ietf.org/doc/html/rfc6763#section-7.2 raise BadTypeInNameException(f"Full name ({type_}) must be > 256 bytes") if type_.endswith((_TCP_PROTOCOL_LOCAL_TRAILER, _NONTCP_PROTOCOL_LOCAL_TRAILER)): remaining = type_[: -len(_TCP_PROTOCOL_LOCAL_TRAILER)].split(".") trailer = type_[-len(_TCP_PROTOCOL_LOCAL_TRAILER) :] has_protocol = True elif strict: raise BadTypeInNameException( f"Type '{type_}' must end with " f"'{_TCP_PROTOCOL_LOCAL_TRAILER}' or '{_NONTCP_PROTOCOL_LOCAL_TRAILER}'" ) elif type_.endswith(_LOCAL_TRAILER): remaining = type_[: -len(_LOCAL_TRAILER)].split(".") trailer = type_[-len(_LOCAL_TRAILER) + 1 :] has_protocol = False else: raise BadTypeInNameException(f"Type '{type_}' must end with '{_LOCAL_TRAILER}'") if strict or has_protocol: service_name = remaining.pop() if not service_name: raise BadTypeInNameException("No Service name found") if len(remaining) == 1 and len(remaining[0]) == 0: raise BadTypeInNameException(f"Type '{type_}' must not start with '.'") if service_name[0] != "_": raise BadTypeInNameException(f"Service name ({service_name}) must start with '_'") test_service_name = service_name[1:] if strict and len(test_service_name) > 15: # https://datatracker.ietf.org/doc/html/rfc6763#section-7.2 raise BadTypeInNameException(f"Service name ({test_service_name}) must be <= 15 bytes") if "--" in test_service_name: raise BadTypeInNameException(f"Service name ({test_service_name}) must not contain '--'") if "-" in (test_service_name[0], test_service_name[-1]): raise BadTypeInNameException(f"Service name ({test_service_name}) may not start or end with '-'") if not _HAS_A_TO_Z.search(test_service_name): raise BadTypeInNameException( f"Service name ({test_service_name}) must contain at least one letter (eg: 'A-Z')" ) allowed_characters_re = ( _HAS_ONLY_A_TO_Z_NUM_HYPHEN if strict else _HAS_ONLY_A_TO_Z_NUM_HYPHEN_UNDERSCORE ) if not allowed_characters_re.search(test_service_name): raise BadTypeInNameException( f"Service name ({test_service_name if strict else ''}) " "must contain only these characters: " "A-Z, a-z, 0-9, hyphen ('-')" + ", underscore ('_')" if strict else "" ) else: service_name = "" 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(f"Too long: '{remaining[0]}'") if _HAS_ASCII_CONTROL_CHARS.search(remaining[0]): raise BadTypeInNameException( f"Ascii control character 0x00-0x1F and 0x7F illegal in '{remaining[0]}'" ) return service_name + trailer def possible_types(name: str) -> set[str]: """Build a set of all possible types from a fully qualified name.""" labels = name.split(".") label_count = len(labels) types = set() for count in range(label_count): parts = labels[label_count - count - 4 :] if not parts[0].startswith("_"): break types.add(".".join(parts)) return types cached_possible_types = lru_cache(maxsize=256)(possible_types)