v1.3.5

2026-08-02 18:57:40 +02:00
parent 5e5ab8681a
commit 6fa59321c0
5759 changed files with 712133 additions and 66 deletions
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+########################################################################
+# File name: stringprep.py
+# This file is part of: aiosasl
+#
+# LICENSE
+#
+# This program 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 3 of the
+# License, or (at your option) any later version.
+#
+# This program 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 program.  If not, see
+# <http://www.gnu.org/licenses/>.
+#
+########################################################################
+"""
+Stringprep support
+##################
+
+This module implements the SASLprep (`RFC 4013`_) stringprep profile.
+
+.. autofunction:: saslprep
+
+.. _RFC 4013: https://tools.ietf.org/html/rfc4013
+
+"""
+
+import stringprep
+import typing
+
+from unicodedata import ucd_3_2_0 as unicodedata
+
+_nodeprep_prohibited = frozenset("\"&'/:<>@")
+
+
+def is_RandALCat(c: str) -> bool:
+    return unicodedata.bidirectional(c) in ("R", "AL")
+
+
+def is_LCat(c: str) -> bool:
+    return unicodedata.bidirectional(c) == "L"
+
+
+TablePredicate = typing.Callable[[str], bool]
+
+
+def check_against_tables(
+        chars: typing.Iterable[str],
+        tables: typing.Iterable[TablePredicate],
+        ) -> typing.Optional[str]:
+    """
+    Perform a check against the table predicates in `tables`. `tables` must be
+    a reusable iterable containing characteristic functions of character sets,
+    that is, functions which return :data:`True` if the character is in the
+    table.
+
+    The function returns the first character occuring in any of the tables or
+    :data:`None` if no character matches.
+    """
+
+    for c in chars:
+        if any(in_table(c) for in_table in tables):
+            return c
+
+    return None
+
+
+def do_normalization(chars: typing.MutableSequence[str]) -> None:
+    """
+    Perform the stringprep normalization. Operates in-place on a list of
+    unicode characters provided in `chars`.
+    """
+    chars[:] = list(unicodedata.normalize("NFKC", "".join(chars)))
+
+
+def check_bidi(chars: typing.Sequence[str]) -> None:
+    """
+    Check proper bidirectionality as per stringprep. Operates on a list of
+    unicode characters provided in `chars`.
+    """
+
+    # the empty string is valid, as it cannot violate the RandALCat constraints
+    if not chars:
+        return
+
+    # first_is_RorAL = unicodedata.bidirectional(chars[0]) in {"R", "AL"}
+    # if first_is_RorAL:
+
+    has_RandALCat = any(is_RandALCat(c) for c in chars)
+    if not has_RandALCat:
+        return
+
+    has_LCat = any(is_LCat(c) for c in chars)
+    if has_LCat:
+        raise ValueError("L and R/AL characters must not occur in the same"
+                         " string")
+
+    if not is_RandALCat(chars[0]) or not is_RandALCat(chars[-1]):
+        raise ValueError("R/AL string must start and end with R/AL character.")
+
+
+def check_prohibited_output(
+        chars: typing.Sequence[str],
+        bad_tables: typing.Iterable[TablePredicate]) -> None:
+    """
+    Check against prohibited output, by checking whether any of the characters
+    from `chars` are in any of the `bad_tables`.
+
+    Operates in-place on a list of code points from `chars`.
+    """
+    violator = check_against_tables(chars, bad_tables)
+    if violator is not None:
+        raise ValueError("Input contains invalid unicode codepoint: "
+                         "U+{:04x}".format(ord(violator)))
+
+
+def check_unassigned(chars: typing.Sequence[str],
+                     bad_tables: typing.Iterable[TablePredicate]) -> None:
+    """
+    Check that `chars` does not contain any unassigned code points as per
+    the given list of `bad_tables`.
+
+    Operates on a list of unicode code points provided in `chars`.
+    """
+    bad_tables = (
+        stringprep.in_table_a1,)
+
+    violator = check_against_tables(chars, bad_tables)
+    if violator is not None:
+        raise ValueError("Input contains unassigned code point: "
+                         "U+{:04x}".format(ord(violator)))
+
+
+def _saslprep_do_mapping(chars: typing.MutableSequence[str]) -> None:
+    """
+    Perform the stringprep mapping step of SASLprep. Operates in-place on a
+    list of unicode characters provided in `chars`.
+    """
+    i = 0
+    while i < len(chars):
+        c = chars[i]
+        if stringprep.in_table_c12(c):
+            chars[i] = "\u0020"
+        elif stringprep.in_table_b1(c):
+            del chars[i]
+            continue
+        i += 1
+
+
+def saslprep(string: str,
+             allow_unassigned: bool = False) -> str:
+    """
+    Process the given `string` using the SASLprep profile. In the error cases
+    defined in `RFC 3454`_ (stringprep), a :class:`ValueError` is raised.
+    """
+
+    chars = list(string)
+    _saslprep_do_mapping(chars)
+    do_normalization(chars)
+    check_prohibited_output(
+        chars,
+        (
+            stringprep.in_table_c12,
+            stringprep.in_table_c21,
+            stringprep.in_table_c22,
+            stringprep.in_table_c3,
+            stringprep.in_table_c4,
+            stringprep.in_table_c5,
+            stringprep.in_table_c6,
+            stringprep.in_table_c7,
+            stringprep.in_table_c8,
+            stringprep.in_table_c9
+        )
+    )
+    check_bidi(chars)
+
+    if not allow_unassigned:
+        check_unassigned(
+            chars,
+            (
+                stringprep.in_table_a1,
+            )
+        )
+
+    return "".join(chars)
+
+
+def trace(string: str) -> str:
+    """
+    Implement the ``trace`` profile specified in :rfc:`4505`.
+    """
+
+    check_prohibited_output(
+        string,
+        (
+            stringprep.in_table_c21,
+            stringprep.in_table_c22,
+            stringprep.in_table_c3,
+            stringprep.in_table_c4,
+            stringprep.in_table_c5,
+            stringprep.in_table_c6,
+            stringprep.in_table_c8,
+            stringprep.in_table_c9,
+        )
+    )
+    check_bidi(string)
+    return string