621 lines
23 KiB
Python
621 lines
23 KiB
Python
import bisect
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import re
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import unicodedata
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import warnings
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from typing import Optional, Union
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from . import idnadata
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from .intranges import intranges_contain
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_virama_combining_class = 9
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_alabel_prefix = b"xn--"
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_unicode_dots_re = re.compile("[\u002e\u3002\uff0e\uff61]")
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# Bidi category sets from RFC 5893, hoisted out of the per-codepoint loop
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_bidi_rtl_first = frozenset({"R", "AL"})
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_bidi_rtl_categories = frozenset({"R", "AL", "AN"})
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_bidi_rtl_allowed = frozenset({"R", "AL", "AN", "EN", "ES", "CS", "ET", "ON", "BN", "NSM"})
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_bidi_rtl_valid_ending = frozenset({"R", "AL", "EN", "AN"})
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_bidi_rtl_numeric = frozenset({"AN", "EN"})
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_bidi_ltr_allowed = frozenset({"L", "EN", "ES", "CS", "ET", "ON", "BN", "NSM"})
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_bidi_ltr_valid_ending = frozenset({"L", "EN"})
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_bidi_joiner_l_or_d = frozenset({ord("L"), ord("D")})
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_bidi_joiner_r_or_d = frozenset({ord("R"), ord("D")})
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class IDNAError(UnicodeError):
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"""Base exception for all IDNA-encoding related problems"""
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pass
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class IDNABidiError(IDNAError):
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"""Exception when bidirectional requirements are not satisfied"""
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pass
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class InvalidCodepoint(IDNAError):
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"""Exception when a disallowed or unallocated codepoint is used"""
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pass
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class InvalidCodepointContext(IDNAError):
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"""Exception when the codepoint is not valid in the context it is used"""
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pass
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def _combining_class(cp: int) -> int:
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v = unicodedata.combining(chr(cp))
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if v == 0 and not unicodedata.name(chr(cp)):
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raise ValueError("Unknown character in unicodedata")
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return v
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def _is_script(cp: str, script: str) -> bool:
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return intranges_contain(ord(cp), idnadata.scripts[script])
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def _punycode(s: str) -> bytes:
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return s.encode("punycode")
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def _unot(s: int) -> str:
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return f"U+{s:04X}"
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def valid_label_length(label: Union[bytes, str]) -> bool:
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"""Check that a label does not exceed the maximum permitted length.
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Per :rfc:`1035` (and :rfc:`5891` §4.2.4) a DNS label must not exceed
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63 octets. The argument may be either a :class:`str` (a U-label, where
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length is measured in characters) or :class:`bytes` (an A-label, where
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length is measured in octets).
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:param label: The label to check.
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:returns: ``True`` if the label is within the length limit, otherwise
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``False``.
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"""
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return len(label) <= 63
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def valid_string_length(domain: Union[bytes, str], trailing_dot: bool) -> bool:
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"""Check that a full domain name does not exceed the maximum length.
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Per :rfc:`1035`, a domain name is limited to 253 octets when no trailing
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dot is present, or 254 octets when one is included.
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:param domain: The full (possibly multi-label) domain name.
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:param trailing_dot: ``True`` if ``domain`` includes a trailing ``.``.
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:returns: ``True`` if the domain is within the length limit, otherwise
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``False``.
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"""
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return len(domain) <= (254 if trailing_dot else 253)
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def check_bidi(label: str, check_ltr: bool = False) -> bool:
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"""Validate the Bidi Rule from :rfc:`5893` for a single label.
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The Bidi Rule constrains how bidirectional characters (Hebrew, Arabic,
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etc.) may appear within a label. By default the check is only applied
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when the label contains at least one right-to-left character (Unicode
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bidirectional categories ``R``, ``AL``, or ``AN``); set ``check_ltr``
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to ``True`` to apply it to LTR-only labels as well.
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:param label: The label to validate, as a Unicode string.
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:param check_ltr: If ``True``, apply the rules even when the label
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contains no RTL characters.
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:returns: ``True`` if the label satisfies the Bidi Rule.
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:raises IDNABidiError: If any of Bidi Rule conditions 1-6 are violated,
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or if the directional category of a codepoint cannot be determined.
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"""
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# Bidi rules should only be applied if string contains RTL characters
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bidi_label = False
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for idx, cp in enumerate(label, 1):
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direction = unicodedata.bidirectional(cp)
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if direction == "":
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# String likely comes from a newer version of Unicode
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raise IDNABidiError(f"Unknown directionality in label {repr(label)} at position {idx}")
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if direction in _bidi_rtl_categories:
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bidi_label = True
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if not bidi_label and not check_ltr:
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return True
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# Bidi rule 1
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direction = unicodedata.bidirectional(label[0])
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if direction in _bidi_rtl_first:
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rtl = True
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elif direction == "L":
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rtl = False
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else:
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raise IDNABidiError(f"First codepoint in label {repr(label)} must be directionality L, R or AL")
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valid_ending = False
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number_type: Optional[str] = None
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for idx, cp in enumerate(label, 1):
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direction = unicodedata.bidirectional(cp)
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if rtl:
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# Bidi rule 2
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if direction not in _bidi_rtl_allowed:
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raise IDNABidiError(f"Invalid direction for codepoint at position {idx} in a right-to-left label")
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# Bidi rule 3
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if direction in _bidi_rtl_valid_ending:
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valid_ending = True
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elif direction != "NSM":
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valid_ending = False
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# Bidi rule 4
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if direction in _bidi_rtl_numeric:
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if not number_type:
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number_type = direction
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else:
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if number_type != direction:
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raise IDNABidiError("Can not mix numeral types in a right-to-left label")
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else:
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# Bidi rule 5
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if direction not in _bidi_ltr_allowed:
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raise IDNABidiError(f"Invalid direction for codepoint at position {idx} in a left-to-right label")
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# Bidi rule 6
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if direction in _bidi_ltr_valid_ending:
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valid_ending = True
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elif direction != "NSM":
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valid_ending = False
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if not valid_ending:
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raise IDNABidiError("Label ends with illegal codepoint directionality")
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return True
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def check_initial_combiner(label: str) -> bool:
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"""Reject labels that begin with a combining mark.
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Per :rfc:`5891` §4.2.3.2 a label must not start with a character of
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Unicode general category ``M`` (Mark).
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:param label: The label to check.
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:returns: ``True`` if the first character is not a combining mark.
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:raises IDNAError: If the label begins with a combining character.
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"""
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if unicodedata.category(label[0])[0] == "M":
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raise IDNAError("Label begins with an illegal combining character")
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return True
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def check_hyphen_ok(label: str) -> bool:
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"""Validate the hyphen restrictions for a label.
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Per :rfc:`5891` §4.2.3.1 a label must not start or end with a hyphen
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(``U+002D``), and must not have hyphens in both the third and fourth
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positions (the prefix reserved for A-labels).
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:param label: The label to check.
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:returns: ``True`` if the hyphen restrictions are satisfied.
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:raises IDNAError: If any of the hyphen restrictions are violated.
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"""
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if label[2:4] == "--":
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raise IDNAError("Label has disallowed hyphens in 3rd and 4th position")
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if label[0] == "-" or label[-1] == "-":
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raise IDNAError("Label must not start or end with a hyphen")
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return True
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def check_nfc(label: str) -> None:
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"""Require that a label is in Unicode Normalization Form C.
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:param label: The label to check.
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:raises IDNAError: If ``label`` differs from its NFC normalisation.
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"""
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if unicodedata.normalize("NFC", label) != label:
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raise IDNAError("Label must be in Normalization Form C")
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def valid_contextj(label: str, pos: int) -> bool:
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"""Validate the CONTEXTJ rules from :rfc:`5892` Appendix A.
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These rules govern the contextual use of the joiner codepoints
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``U+200C`` (ZERO WIDTH NON-JOINER, Appendix A.1) and ``U+200D``
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(ZERO WIDTH JOINER, Appendix A.2) within a label.
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:param label: The label containing the codepoint.
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:param pos: Index of the joiner codepoint within ``label``.
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:returns: ``True`` if the codepoint at ``pos`` satisfies its CONTEXTJ
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rule, ``False`` otherwise (including when the codepoint at
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``pos`` is not a recognised joiner).
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:raises ValueError: If an adjacent codepoint has no Unicode name when
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determining its combining class.
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"""
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cp_value = ord(label[pos])
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if cp_value == 0x200C:
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if pos > 0 and _combining_class(ord(label[pos - 1])) == _virama_combining_class:
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return True
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ok = False
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for i in range(pos - 1, -1, -1):
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joining_type = idnadata.joining_types().get(ord(label[i]))
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if joining_type == ord("T"):
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continue
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elif joining_type in _bidi_joiner_l_or_d:
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ok = True
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break
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else:
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break
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if not ok:
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return False
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ok = False
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for i in range(pos + 1, len(label)):
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joining_type = idnadata.joining_types().get(ord(label[i]))
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if joining_type == ord("T"):
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continue
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elif joining_type in _bidi_joiner_r_or_d:
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ok = True
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break
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else:
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break
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return ok
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if cp_value == 0x200D:
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return pos > 0 and _combining_class(ord(label[pos - 1])) == _virama_combining_class
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else:
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return False
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def valid_contexto(label: str, pos: int, exception: bool = False) -> bool:
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"""Validate the CONTEXTO rules from :rfc:`5892` Appendix A.
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Covers the contextual rules for codepoints such as MIDDLE DOT
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(``U+00B7``), Greek lower numeral sign, Hebrew punctuation, Katakana
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middle dot, and the Arabic-Indic / Extended Arabic-Indic digit ranges.
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:param label: The label containing the codepoint.
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:param pos: Index of the codepoint within ``label``.
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:param exception: Reserved for forward compatibility; currently unused.
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:returns: ``True`` if the codepoint at ``pos`` satisfies its CONTEXTO
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rule, ``False`` otherwise (including when the codepoint is not a
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recognised CONTEXTO codepoint).
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"""
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cp_value = ord(label[pos])
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if cp_value == 0x00B7:
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return 0 < pos < len(label) - 1 and ord(label[pos - 1]) == 0x006C and ord(label[pos + 1]) == 0x006C
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elif cp_value == 0x0375:
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if pos < len(label) - 1 and len(label) > 1:
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return _is_script(label[pos + 1], "Greek")
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return False
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elif cp_value == 0x05F3 or cp_value == 0x05F4:
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if pos > 0:
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return _is_script(label[pos - 1], "Hebrew")
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return False
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elif cp_value == 0x30FB:
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for cp in label:
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if cp == "\u30fb":
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continue
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if _is_script(cp, "Hiragana") or _is_script(cp, "Katakana") or _is_script(cp, "Han"):
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return True
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return False
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elif 0x660 <= cp_value <= 0x669:
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return not any(0x6F0 <= ord(cp) <= 0x06F9 for cp in label)
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elif 0x6F0 <= cp_value <= 0x6F9:
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return not any(0x660 <= ord(cp) <= 0x0669 for cp in label)
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return False
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def check_label(label: Union[str, bytes, bytearray]) -> None:
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"""Run the full set of IDNA 2008 validity checks on a single label.
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Applies, in order: NFC normalisation (:func:`check_nfc`), hyphen
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restrictions (:func:`check_hyphen_ok`), the no-leading-combiner rule
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(:func:`check_initial_combiner`), per-codepoint validity (PVALID,
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CONTEXTJ, CONTEXTO classes from :rfc:`5892`), and the Bidi Rule
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(:func:`check_bidi`).
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:param label: The label to validate. ``bytes`` or ``bytearray`` input
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is decoded as UTF-8 first.
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:raises IDNAError: If the label is empty or fails a structural rule.
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:raises InvalidCodepoint: If the label contains a DISALLOWED or
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UNASSIGNED codepoint.
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:raises InvalidCodepointContext: If a CONTEXTJ or CONTEXTO codepoint
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is not valid in its context.
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:raises IDNABidiError: If the Bidi Rule is violated.
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"""
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if isinstance(label, (bytes, bytearray)):
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label = label.decode("utf-8")
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if len(label) == 0:
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raise IDNAError("Empty Label")
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# Reject on domain length rather than label length so support some UTS 46
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# use cases, still reducing processing of label contextual rules
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if not valid_string_length(label, trailing_dot=True):
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raise IDNAError("Label too long")
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check_nfc(label)
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check_hyphen_ok(label)
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check_initial_combiner(label)
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for pos, cp in enumerate(label):
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cp_value = ord(cp)
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if intranges_contain(cp_value, idnadata.codepoint_classes["PVALID"]):
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continue
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elif intranges_contain(cp_value, idnadata.codepoint_classes["CONTEXTJ"]):
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try:
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if not valid_contextj(label, pos):
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raise InvalidCodepointContext(
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f"Joiner {_unot(cp_value)} not allowed at position {pos + 1} in {repr(label)}"
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)
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except ValueError as err:
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raise IDNAError(
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f"Unknown codepoint adjacent to joiner {_unot(cp_value)} at position {pos + 1} in {repr(label)}"
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) from err
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elif intranges_contain(cp_value, idnadata.codepoint_classes["CONTEXTO"]):
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if not valid_contexto(label, pos):
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raise InvalidCodepointContext(
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f"Codepoint {_unot(cp_value)} not allowed at position {pos + 1} in {repr(label)}"
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)
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else:
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raise InvalidCodepoint(f"Codepoint {_unot(cp_value)} at position {pos + 1} of {repr(label)} not allowed")
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check_bidi(label)
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def alabel(label: str) -> bytes:
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"""Convert a single U-label into its A-label form.
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The result is the ASCII-Compatible Encoding (ACE) form per :rfc:`5891`
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§4: the label is validated, Punycode-encoded, and prefixed with
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``xn--``. Pure ASCII labels that are already valid IDNA labels are
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returned unchanged (as :class:`bytes`).
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:param label: The label to convert, as a Unicode string.
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:returns: The A-label as ASCII-encoded :class:`bytes`.
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:raises IDNAError: If the label is invalid or the resulting A-label
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exceeds 63 octets.
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"""
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try:
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label_bytes = label.encode("ascii")
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ulabel(label_bytes)
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if not valid_label_length(label_bytes):
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raise IDNAError("Label too long")
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return label_bytes
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except UnicodeEncodeError:
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pass
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check_label(label)
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label_bytes = _alabel_prefix + _punycode(label)
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if not valid_label_length(label_bytes):
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raise IDNAError("Label too long")
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return label_bytes
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def ulabel(label: Union[str, bytes, bytearray]) -> str:
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"""Convert a single A-label into its U-label form.
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Performs the inverse of :func:`alabel`: an ``xn--``-prefixed label is
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Punycode-decoded and validated. Labels that are already Unicode (or
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plain ASCII without the ACE prefix) are validated and returned as a
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Unicode string.
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:param label: The label to convert. ``bytes`` or ``bytearray`` input
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is treated as ASCII.
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:returns: The U-label as a Unicode string.
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:raises IDNAError: If the label is malformed or fails validation.
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"""
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if not isinstance(label, (bytes, bytearray)):
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try:
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label_bytes = label.encode("ascii")
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except UnicodeEncodeError:
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check_label(label)
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return label
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else:
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label_bytes = bytes(label)
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label_bytes = label_bytes.lower()
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if label_bytes.startswith(_alabel_prefix):
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label_bytes = label_bytes[len(_alabel_prefix) :]
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if not label_bytes:
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raise IDNAError("Malformed A-label, no Punycode eligible content found")
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if label_bytes.endswith(b"-"):
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raise IDNAError("A-label must not end with a hyphen")
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else:
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check_label(label_bytes)
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return label_bytes.decode("ascii")
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try:
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label = label_bytes.decode("punycode")
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except UnicodeError as err:
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raise IDNAError("Invalid A-label") from err
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check_label(label)
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return label
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def uts46_remap(domain: str, std3_rules: bool = True, transitional: bool = False) -> str:
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"""Apply the UTS #46 character mapping to a domain string.
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Implements the mapping table from `UTS #46 §4
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<https://www.unicode.org/reports/tr46/>`_: each character is kept,
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replaced, or rejected based on its status (``V``, ``M``, ``D``, ``3``,
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``I``). The result is returned in Normalisation Form C.
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:param domain: The full domain name to remap.
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:param std3_rules: If ``True``, apply the stricter STD3 ASCII rules
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(status ``3`` codepoints raise instead of being kept or mapped).
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:param transitional: If ``True``, use transitional processing (status
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``D`` codepoints are mapped instead of kept). Transitional
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processing has been removed from UTS #46 and this option is
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retained only for backwards compatibility.
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:returns: The remapped domain, in Normalisation Form C.
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:raises InvalidCodepoint: If the domain contains a disallowed
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codepoint under the chosen rules.
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"""
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from .uts46data import uts46data
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output = ""
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for pos, char in enumerate(domain):
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code_point = ord(char)
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uts46row = uts46data[code_point if code_point < 256 else bisect.bisect_left(uts46data, (code_point, "Z")) - 1]
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status = uts46row[1]
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replacement: Optional[str] = None
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if len(uts46row) == 3:
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replacement = uts46row[2] # ty: ignore[index-out-of-bounds]
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# UTS #46 §4: V is always valid, D is deviation (kept unless transitional),
|
|
# 3 is disallowed-STD3 (kept unmapped if std3_rules is off and no mapping).
|
|
keep_as_is = (
|
|
status == "V" or (status == "D" and not transitional) or (status == "3" and not std3_rules and replacement is None)
|
|
)
|
|
# M is mapped, 3-with-replacement and transitional D fall through to the
|
|
# same replacement output path.
|
|
use_replacement = replacement is not None and (
|
|
status == "M" or (status == "3" and not std3_rules) or (status == "D" and transitional)
|
|
)
|
|
|
|
if keep_as_is:
|
|
output += char
|
|
elif use_replacement:
|
|
assert replacement is not None # narrowed by use_replacement
|
|
output += replacement
|
|
elif status == "I":
|
|
continue
|
|
else:
|
|
raise InvalidCodepoint(f"Codepoint {_unot(code_point)} not allowed at position {pos + 1} in {repr(domain)}")
|
|
|
|
return unicodedata.normalize("NFC", output)
|
|
|
|
|
|
def encode(
|
|
s: Union[str, bytes, bytearray],
|
|
strict: bool = False,
|
|
uts46: bool = False,
|
|
std3_rules: bool = False,
|
|
transitional: bool = False,
|
|
) -> bytes:
|
|
"""Encode a Unicode domain name into its ASCII (A-label) form.
|
|
|
|
Splits the input on label separators (only ``U+002E`` if ``strict`` is
|
|
set; otherwise also IDEOGRAPHIC FULL STOP ``U+3002``, FULLWIDTH FULL
|
|
STOP ``U+FF0E``, and HALFWIDTH IDEOGRAPHIC FULL STOP ``U+FF61``),
|
|
encodes each label with :func:`alabel`, and rejoins them with ``.``.
|
|
Optionally pre-processes the input through :func:`uts46_remap`.
|
|
|
|
:param s: The domain name to encode.
|
|
:param strict: If ``True``, only ``U+002E`` is recognised as a label
|
|
separator.
|
|
:param uts46: If ``True``, apply UTS #46 mapping before encoding.
|
|
:param std3_rules: Forwarded to :func:`uts46_remap` when ``uts46`` is
|
|
``True``.
|
|
:param transitional: Forwarded to :func:`uts46_remap` when ``uts46``
|
|
is ``True``. Deprecated: emits a :class:`DeprecationWarning` and
|
|
will be removed in a future version.
|
|
:returns: The encoded domain as ASCII :class:`bytes`.
|
|
:raises IDNAError: If the domain is empty, contains an invalid label,
|
|
or exceeds the maximum domain length.
|
|
"""
|
|
if transitional:
|
|
warnings.warn(
|
|
"Transitional processing has been removed from UTS #46. "
|
|
"The transitional argument will be removed in a future version.",
|
|
DeprecationWarning,
|
|
stacklevel=2,
|
|
)
|
|
if not isinstance(s, str):
|
|
try:
|
|
s = str(s, "ascii")
|
|
except (UnicodeDecodeError, TypeError) as err:
|
|
raise IDNAError("should pass a unicode string to the function rather than a byte string.") from err
|
|
if uts46:
|
|
s = uts46_remap(s, std3_rules, transitional)
|
|
|
|
# Reject inputs that exceed the maximum DNS domain length up-front
|
|
# to avoid expensive computation on long inputs.
|
|
if not valid_string_length(s, trailing_dot=True):
|
|
raise IDNAError("Domain too long")
|
|
|
|
trailing_dot = False
|
|
result = []
|
|
labels = s.split(".") if strict else _unicode_dots_re.split(s)
|
|
if not labels or labels == [""]:
|
|
raise IDNAError("Empty domain")
|
|
if labels[-1] == "":
|
|
del labels[-1]
|
|
trailing_dot = True
|
|
for label in labels:
|
|
s = alabel(label)
|
|
if s:
|
|
result.append(s)
|
|
else:
|
|
raise IDNAError("Empty label")
|
|
if trailing_dot:
|
|
result.append(b"")
|
|
s = b".".join(result)
|
|
if not valid_string_length(s, trailing_dot):
|
|
raise IDNAError("Domain too long")
|
|
return s
|
|
|
|
|
|
def decode(
|
|
s: Union[str, bytes, bytearray],
|
|
strict: bool = False,
|
|
uts46: bool = False,
|
|
std3_rules: bool = False,
|
|
) -> str:
|
|
"""Decode an A-label-encoded domain name back to Unicode.
|
|
|
|
Splits the input on label separators (see :func:`encode` for the
|
|
rules), decodes each label with :func:`ulabel`, and rejoins them
|
|
with ``.``. Optionally pre-processes the input through
|
|
:func:`uts46_remap`.
|
|
|
|
:param s: The domain name to decode.
|
|
:param strict: If ``True``, only ``U+002E`` is recognised as a label
|
|
separator.
|
|
:param uts46: If ``True``, apply UTS #46 mapping before decoding.
|
|
:param std3_rules: Forwarded to :func:`uts46_remap` when ``uts46`` is
|
|
``True``.
|
|
:returns: The decoded domain as a Unicode string.
|
|
:raises IDNAError: If the input is not valid ASCII, contains an
|
|
invalid label, or is empty.
|
|
"""
|
|
if not isinstance(s, str):
|
|
try:
|
|
s = str(s, "ascii")
|
|
except (UnicodeDecodeError, TypeError) as err:
|
|
raise IDNAError("Invalid ASCII in A-label") from err
|
|
if uts46:
|
|
s = uts46_remap(s, std3_rules, False)
|
|
# Reject inputs that exceed the maximum DNS domain length up-front
|
|
# to avoid expensive computation on long inputs.
|
|
if not valid_string_length(s, trailing_dot=True):
|
|
raise IDNAError("Domain too long")
|
|
trailing_dot = False
|
|
result = []
|
|
labels = s.split(".") if strict else _unicode_dots_re.split(s)
|
|
if not labels or labels == [""]:
|
|
raise IDNAError("Empty domain")
|
|
if not labels[-1]:
|
|
del labels[-1]
|
|
trailing_dot = True
|
|
for label in labels:
|
|
s = ulabel(label)
|
|
if s:
|
|
result.append(s)
|
|
else:
|
|
raise IDNAError("Empty label")
|
|
if trailing_dot:
|
|
result.append("")
|
|
return ".".join(result)
|