163 lines
5.6 KiB
ReStructuredText
163 lines
5.6 KiB
ReStructuredText
Internationalized Domain Names in Applications (IDNA)
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=====================================================
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A library to support the Internationalised Domain Names in Applications
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(IDNA) protocol as specified in `RFC 5891 <http://tools.ietf.org/html/rfc5891>`_.
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This version of the protocol is often referred to as “IDNA2008”.
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This library also provides support for Unicode Technical Standard 46,
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`Unicode IDNA Compatibility Processing <http://unicode.org/reports/tr46/>`_.
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The library is also intended to act as a suitable replacement for
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the “encodings.idna” module that comes with the Python standard library
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but currently only supports the older, deprecated IDNA specification
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(`RFC 3490 <http://tools.ietf.org/html/rfc3490>`_).
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Its basic functions are simply executed:
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.. code-block:: pycon
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>>> import idna
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>>> idna.encode(u'ドメイン.テスト')
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'xn--eckwd4c7c.xn--zckzah'
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>>> print idna.decode('xn--eckwd4c7c.xn--zckzah')
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ドメイン.テスト
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Packages
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--------
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The latest tagged release version is published in the PyPI repository:
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.. image:: https://badge.fury.io/py/idna.svg
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:target: http://badge.fury.io/py/idna
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Installation
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------------
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To install this library, you can use PIP:
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.. code-block:: bash
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$ pip install idna
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Alternatively, you can install the package using the bundled setup script:
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.. code-block:: bash
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$ python setup.py install
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This library should work with Python 2.7, and Python 3.3 or later.
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Usage
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-----
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For typical usage, the ``encode`` and ``decode`` functions will take a domain
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name argument and perform a conversion to an A-label or U-label respectively.
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.. code-block:: pycon
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>>> import idna
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>>> idna.encode(u'ドメイン.テスト')
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'xn--eckwd4c7c.xn--zckzah'
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>>> print idna.decode('xn--eckwd4c7c.xn--zckzah')
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ドメイン.テスト
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You may use the codec encoding and decoding methods using the
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``idna.codec`` module.
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.. code-block:: pycon
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>>> import idna.codec
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>>> print u'домена.испытание'.encode('idna')
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xn--80ahd1agd.xn--80akhbyknj4f
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>>> print 'xn--80ahd1agd.xn--80akhbyknj4f'.decode('idna')
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домена.испытание
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Conversions can be applied at a per-label basis using the ``ulabel`` or ``alabel``
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functions if necessary:
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.. code-block:: pycon
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>>> idna.alabel(u'测试')
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'xn--0zwm56d'
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Compatibility Mapping (UTS #46)
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+++++++++++++++++++++++++++++++
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As described in `RFC 5895 <http://tools.ietf.org/html/rfc5895>`_, the IDNA
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specification no longer including mappings from different forms of input that
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a user may enter, to the form that is provided to the IDNA functions. This
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functionality is now considered by the specification to be a local
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user-interface issue distinct from IDNA conversion functionality.
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This library support one user-level mapping, that developed by the Unicode
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Consortium, known as `Unicode IDNA Compatibility Processing <http://unicode.org/reports/tr46/>`_.
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It provides for both regular mapping and transitional mapping.
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For example, "Königsgäßchen" is not a permissible label as LATIN CAPITAL
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LETTER K is not allowed (as are capital letters in general). UTS46 will convert
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this into lower case.
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.. code-block:: pycon
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>>> import idna
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>>> idna.encode(u'Königsgäßchen')
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...
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idna.core.InvalidCodepoint: Codepoint U+004B at position 1 of u'K\xf6nigsg\xe4\xdfchen' not allowed
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>>> idna.encode(u'Königsgäßchen', uts46=True)
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'xn--knigsgchen-b4a3dun'
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Transitional processing provides conversions to help transition from the older
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2003 standard to the current standard. For example, in the original IDNA
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specification, the LATIN SMALL LETTER SHARP S (ß) was converted into two
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LATIN SMALL LETTER S (ss), whereas in the current IDNA specification this
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conversion is not performed.
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.. code-block:: pycon
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>>> idna.encode(u'Königsgäßchen', uts46=True, transitional=True)
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'xn--knigsgsschen-lcb0w'
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Implementors should use transitional processing with caution, only in rare
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cases where conversion from legacy labels to current labels must be performed
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(i.e. IDNA implementations that pre-date 2008). For typical applications
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that just need to convert labels, transitional processing is unlikely to be
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beneficial and could produce unexpected incompatible results.
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``encodings.idna`` Compatibility
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++++++++++++++++++++++++++++++++
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Function calls from the Python built-in ``encodings.idna`` module are
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mapping to their IDNA 2008 equivalents using the ``idna.compat`` module.
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Simply substitute the ``import`` clause in your code to refer to the
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new module name.
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Exceptions
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----------
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All errors raised during the conversion following the specification should
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raise an exception derived from the ``idna.IDNAError`` base class.
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More specific exceptions that may be generated as ``idna.IDNABidiError``
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when the error reflects an illegal combination of left-to-right and right-to-left
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characters in a label; ``idna.InvalidCodepoint`` when a specific codepoint is
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an illegal character in an IDN label (i.e. INVALID); and ``idna.InvalidCodepointContext``
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when the codepoint is illegal based on its positional context (i.e. it is CONTEXTO
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or CONTEXTJ but the contextual requirements are not satisfied.)
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Testing
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-------
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The library has a test suite based on each rule of the IDNA specification, as
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well as test that are provided as part of the Unicode Technical Standard 46,
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`Unicode IDNA Compatibility Processing <http://unicode.org/reports/tr46/>`_.
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The tests are run automatically on each commit to the master branch of the
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idna git repository at Travis CI:
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.. image:: https://travis-ci.org/kjd/idna.svg?branch=master
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:target: https://travis-ci.org/kjd/idna
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