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Internationalized Domain Names in Applications (IDNA)
=====================================================
Support for the Internationalized Domain Names in
Applications (IDNA) protocol as specified in [RFC 5891
]. This is the latest version of
the protocol and is sometimes referred to as “IDNA 2008”.
This library also provides support for Unicode Technical
Standard 46, [Unicode IDNA Compatibility Processing
].
This acts as a suitable replacement for the “encodings.idna”
module that comes with the Python standard library, but which
only supports the older superseded IDNA specification ([RFC 3490
]).
Basic functions are simply executed:
.. code-block:: pycon
>>> import idna
>>> idna.encode('ドメイン.テスト')
b'xn--eckwd4c7c.xn--zckzah'
>>> print(idna.decode('xn--eckwd4c7c.xn--zckzah'))
ドメイン.テスト
Installation
------------
This package is available for installation from PyPI:
.. code-block:: bash
$ python3 -m pip install idna
Usage
-----
For typical usage, the encode and decode functions will take a
domain name argument and perform a conversion to A-labels or U-labels
respectively.
.. code-block:: pycon
>>> import idna
>>> idna.encode('ドメイン.テスト')
b'xn--eckwd4c7c.xn--zckzah'
>>> print(idna.decode('xn--eckwd4c7c.xn--zckzah'))
ドメイン.テスト
You may use the codec encoding and decoding methods using the
``idna.codec`` module:
.. code-block:: pycon
>>> import idna.codec
>>> print('домен.испытание'.encode('idna2008'))
b'xn--d1acufc.xn--80akhbyknj4f'
>>> print(b'xn--d1acufc.xn--80akhbyknj4f'.decode('idna2008'))
домен.испытание
Conversions can be applied at a per-label basis using the ulabel or
alabel functions if necessary:
.. code-block:: pycon
>>> idna.alabel('测试')
b'xn--0zwm56d'
Compatibility Mapping (UTS #46)
+++++++++++++++++++++++++++++++
As described in [RFC 5895], the
IDNA specification does not normalize input from different potential
ways a user may input a domain name. This functionality, known as
a “mapping”, is considered by the specification to be a local
user-interface issue distinct from IDNA conversion functionality.
This library provides one such mapping that was developed by the
Unicode Consortium. Known as [Unicode IDNA Compatibility Processing
], it provides for both a regular
mapping for typical applications, as well as a transitional mapping to
help migrate from older IDNA 2003 applications. Strings are
preprocessed according to Section 4.4 “Preprocessing for IDNA2008”
prior to the IDNA operations.
For example, “Königsgäßchen” is not a permissible label as *LATIN
CAPITAL LETTER K* is not allowed (nor are capital letters in general).
UTS 46 will convert this into lower case prior to applying the IDNA
conversion.
.. code-block:: pycon
>>> import idna
>>> idna.encode('Königsgäßchen')
...
idna.core.InvalidCodepoint: Codepoint U+004B at position 1 of
'Königsgäßchen' not allowed
>>> idna.encode('Königsgäßchen', uts46=True)
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