1 files changed, 92 insertions, 0 deletions
diff --git a/python/samba/tests/krb5/rfc4120_pyasn1.py b/python/samba/tests/krb5/rfc4120_pyasn1.py
new file mode 100644
index 0000000..ad8a6e7
--- /dev/null
+++ b/python/samba/tests/krb5/rfc4120_pyasn1.py
@@ -0,0 +1,92 @@
+# Unix SMB/CIFS implementation.
+# Copyright (C) Catalyst.Net Ltd 2023
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+from samba.tests.krb5.rfc4120_pyasn1_generated import *
+
+# Kerberos strings should generally be treated as UTF‐8 encoded, but asn1ate
+# (the tool which generates Python definitions from our ASN.1 modules) provides
+# no way to specify the encoding to use. By the time we’ve imported
+# ‘rfc4120_pyasn1_generated’, KerberosString in the process having been
+# instantiated as part of several schema objects, it’s too late to change the
+# existing objects. But by overriding the __getattribute__() method on
+# KerberosString, we can have objects of that type, or a subtype thereof,
+# encoded as UTF‐8 strings instead of as ISO-8859-1 strings (the default).
+
+class ReadOnlyUtf8EncodingDict(dict):
+    # Don’t allow any attributes to be set.
+    __slots__ = []
+
+    def __getitem__(self, key):
+        # Get the original item. This will raise KeyError if it’s not present.
+        val = super().__getitem__(key)
+
+        # If anyone wants to know our encoding, say it’s UTF‐8.
+        if key == 'encoding':
+            return 'utf-8'
+
+        return val
+
+    # Python’s default implementations of the following methods don’t call
+    # __getitem__(), so we’ll need to override them with our own replacements.
+    # In behaviour, they are close enough to the originals for our purposes.
+
+    def get(self, key, default=None):
+        try:
+            return self[key]
+        except KeyError:
+            return default
+
+    def items(self):
+        for key in self:
+            yield key, self[key]
+
+    def values(self):
+        for key in self:
+            yield self[key]
+
+    # Don’t let anyone modify the dict’s contents.
+
+    def __setitem__(self, key, val):
+        raise TypeError('item assignment not supported')
+
+    def __delitem__(self, key):
+        raise TypeError('item deletion not supported')
+
+
+KerberosString_get_attribute = KerberosString.__getattribute__
+
+def get_attribute_override(self, attr):
+    # Get the original attribute. This will raise AttributeError if it’s not
+    # present.
+    val = KerberosString_get_attribute(self, attr)
+
+    # If anyone wants to know our encoding, say it’s UTF‐8.
+    if attr == 'encoding':
+        return 'utf-8'
+
+    if attr == '_readOnly':
+        # Return a copy of the read‐only attributes with the encoding overridden
+        # to be UTF-8. To avoid the possibility of changes being made to the
+        # original dict that do not propagate to its copies, the returned dict
+        # does not allow modification of its contents. Besides, this is supposed
+        # to be read‐only.
+        return ReadOnlyUtf8EncodingDict(val)
+
+    return val
+
+# Override the __getattribute__() method on KerberosString.
+KerberosString.__getattribute__ = get_attribute_override