ens-normalize 2.0.1

Ethereum Name Service (ENS) Name Normalizer

ENS Normalize Python

• Python implementation of the ENS Name Normalization Standard. Thanks to Adraffy for his leadership in coordinating the definition of this standard with the ENS community.
• Passes 100% of the official validation tests (validated automatically with pytest, see below).
• Passes an additional suite of further tests for compatibility with the official Javascript reference implementation and code testing coverage.
• Based on JavaScript implementation version 1.9.0.

Glossary

• name - a full domain name, e.g. nick.eth
• label - a part of a name separated by a dot, e.g. nick and eth are labels in nick.eth
• normalized name - name that is already in normalized form according to the ENS Normalization Standard
• normalizable name - name that is normalized or that can be converted into a normalized name using ens_normalize
• disallowed name - name that is not normalized or normalizable
• curable name - name that may be disallowed but can still be converted into a normalized name using ens_cure
• fatal error - a DisallowedNameError object thrown by ens_normalize that contains only general information about the error and no possible fixes
• curable error - a CurableError object (inherits from DisallowedNameError) thrown by ens_normalize that contains information about a possible fix for the error

Usage

The package is available on pypi

pip install ens-normalize

Normalize an ENS name:

from ens_normalize import ens_normalize
# str -> str
# raises DisallowedNameError for disallowed names
# output ready for namehash
ens_normalize('Nick.ETH')
# 'nick.eth'
# note: does not enforce .eth TLD 3-character minimum

Inspect issues with names that cannot be normalized:

from ens_normalize import DisallowedNameError
# added a hidden "zero width joiner" character
try:
    ens_normalize('Ni‍ck.ETH')
# Catch the first normalization error (the name we are attempting to normalize could have more than one error).
except DisallowedNameError as e:
    # error code
    print(e.code)
    # INVISIBLE

    # a message about why the input is disallowed
    print(e.general_info)
    # Contains a disallowed invisible character

    if isinstance(e, CurableError):
        # information about the disallowed substring
        print(e.disallowed_sequence_info)
        # 'This invisible character is disallowed'

        # starting index of the disallowed substring in the input string
        # (counting in Unicode code points)
        print(e.index)
        # 2

        # the disallowed substring
        # (use repr() to "see" the invisible character)
        print(repr(e.disallowed))
        # '\u200d'

        # a suggestion for fixing the first error (there might be more errors)
        print(repr(e.suggested))
        # ''
        # replacing the disallowed substring with this empty string represents that the disallowed substring should be removed

        # You may be able to fix this error by replacing e.disallowed
        # with e.suggested in the input string.
        # Fields index, disallowed_sequence_info, disallowed, and suggested are not None only for fixable errors.
        # Other errors might be found even after applying this suggestion.

You can attempt conversion of disallowed names into normalized names:

from ens_normalize import ens_cure
# input name with disallowed zero width joiner and '?'
# str -> str
ens_cure('Ni‍ck?.ETH')
# 'nick.eth'
# ZWJ and '?' are removed, no error is raised
# note: this function is not a part of the ENS Normalization Standard

# note: might still raise DisallowedNameError for certain names, which cannot be cured, e.g.
ens_cure('?')
# DisallowedNameError: The name is empty
ens_cure('0χх0.eth')
# DisallowedNameError: Contains visually confusing characters that are disallowed

Format names with fully-qualified emoji:

from ens_normalize import ens_beautify
# works like ens_normalize()
# output ready for display
ens_beautify('1⃣2⃣.eth')
# '1️⃣2️⃣.eth'

# note: normalization is unchanged:
# ens_normalize(ens_beautify(x)) == ens_normalize(x)
# note: in addition to beautifying emojis, ens_beautify converts the character 'ξ' (Greek lowercase 'Xi') to 'Ξ' (Greek uppercase 'Xi', a.k.a. the Ethereum symbol) in labels that contain no other Greek characters

Generate detailed label analysis:

from ens_normalize import ens_tokenize
# str -> List[Token]
# always returns a tokenization of the input
ens_tokenize('Nàme‍🧙‍♂.eth')
# [TokenMapped(cp=78, cps=[110], type='mapped'),
#  TokenNFC(input=[97, 768], cps=[224], type='nfc'),
#  TokenValid(cps=[109, 101], type='valid'),
#  TokenDisallowed(cp=8205, type='disallowed'),
#  TokenEmoji(emoji=[129497, 8205, 9794, 65039],
#             input=[129497, 8205, 9794],
#             cps=[129497, 8205, 9794],
#             type='emoji'),
#  TokenStop(cp=46, type='stop'),
#  TokenValid(cps=[101, 116, 104], type='valid')]

For a normalizable name, you can find out how the input is transformed during normalization:

from ens_normalize import ens_transformations
# Returns a list of transformations (substring -> string)
# that have been applied to the input during normalization.
# NormalizationTransformation has the same fields as CurableError:
# - code
# - general_info
# - disallowed_sequence_info
# - index
# - disallowed
# - suggested
ens_transformations('Nàme🧙‍♂️.eth')
# [NormalizationTransformation(code="MAPPED", index=0, disallowed="N", suggested="n"),
#  NormalizationTransformation(code="FE0F", index=4, disallowed="🧙‍♂️", suggested="🧙‍♂")]

An example normalization workflow:

name = 'Nàme🧙‍♂️.eth'
try:
    normalized = ens_normalize(name)
    print('Normalized:', normalized)
    # Normalized: nàme🧙‍♂.eth
    # Success!

     # was the input transformed by the normalization process?
    if name != normalized:
        # Let's check how the input was changed:
        for t in ens_transformations(name):
            print(repr(t)) # use repr() to print more information
        # NormalizationTransformation(code="MAPPED", index=0, disallowed="N", suggested="n")
        # NormalizationTransformation(code="FE0F", index=4, disallowed="🧙‍♂️", suggested="🧙‍♂")
        #                              invisible character inside emoji ^
except DisallowedNameError as e:
    # Even if the name is invalid according to the ENS Normalization Standard,
    # we can try to automatically remove disallowed characters.
    try:
        print(ens_cure(name))
    except DisallowedLabelError as e:
        # The name cannot be automatically fixed.
        print('Fatal error:', e)

You can run many of the above functions at once. It is faster than running all of them sequentially.

from ens_normalize import ens_process
# use only the do_* flags you need
ens_process("Nàme🧙‍♂️1⃣.eth",
    do_normalize=True,
    do_beautify=True,
    do_tokenize=True,
    do_transformations=True,
    do_cure=True,
)
# ENSProcessResult(
#   normalized='nàme🧙\u200d♂1⃣.eth',
#   beautified='nàme🧙\u200d♂️1️⃣.eth',
#   tokens=[...],
#   cured='nàme🧙\u200d♂1⃣.eth',
#   cures=[], # This is the list of cures that were applied to the input (in this case, none).
#   error=None, # This is the exception raised by ens_normalize().
#               # It is a DisallowedNameError or CurableError if the error is curable.
#   transformations=[
#     NormalizationTransformation(code="MAPPED", index=0, disallowed="N", suggested="n"),
#     NormalizationTransformation(code="FE0F", index=4, disallowed="🧙‍♂️", suggested="🧙‍♂")
#   ])

List of all DisallowedNameError types

For fatal errors (not curable), it is challenging to communicate the normalization error as a problem with a specific substring.

DisallowedNameErrorType	General info
EMPTY_NAME	The name is empty
NSM_REPEATED	Contains a repeated non-spacing mark
NSM_TOO_MANY	Contains too many consecutive non-spacing marks
CONF_WHOLE	Contains visually confusing characters from {script1} and {script2} scripts

List of all CurableError types

Curable errors contain additional information about the disallowed substring.

CurableErrorType	General info	Disallowed sequence info
UNDERSCORE	Contains an underscore in a disallowed position	An underscore is only allowed at the start of a label
HYPHEN	Contains the sequence '--' in a disallowed position	Hyphens are disallowed at the 2nd and 3rd positions of a label
EMPTY_LABEL	Contains a disallowed empty label	Empty labels are not allowed, e.g. abc..eth
CM_START	Contains a combining mark in a disallowed position at the start of the label	A combining mark is disallowed at the start of a label
CM_EMOJI	Contains a combining mark in a disallowed position after an emoji	A combining mark is disallowed after an emoji
DISALLOWED	Contains a disallowed character	This character is disallowed
INVISIBLE	Contains a disallowed invisible character	This invisible character is disallowed
FENCED_LEADING	Contains a disallowed character at the start of a label	This character is disallowed at the start of a label
FENCED_MULTI	Contains a disallowed consecutive sequence of characters	Characters in this sequence cannot be placed next to each other
FENCED_TRAILING	Contains a disallowed character at the end of a label	This character is disallowed at the end of a label
CONF_MIXED	Contains visually confusing characters from multiple scripts ({script1}/{script2})	This character from the {script1} script is disallowed because it is visually confusing with another character from the {script2} script

List of all normalization transformations

NormalizationTransformationType	General info	Disallowed sequence info
IGNORED	Contains disallowed "ignored" characters that have been removed	This character is ignored during normalization and has been automatically removed
MAPPED	Contains a disallowed character that has been replaced by a normalized sequence	This character is disallowed and has been automatically replaced by a normalized sequence
FE0F	Contains a disallowed variant of an emoji which has been replaced by an equivalent normalized emoji	This emoji has been automatically fixed to remove an invisible character
NFC	Contains a disallowed sequence that is not "NFC normalized" which has been replaced by an equivalent normalized sequence	This sequence has been automatically normalized into NFC canonical form

Develop

Update this library to the latest ENS normalization specification (optional)

This library uses files defining the normalization standard directly from the official Javascript implementation. When the standard is updated with new characters, this library can be updated by running the following steps:

1. Requirements:

   • Node.js >= 18
   • npm

2. Set the hash of the latest commit from the JavaScript library inside package.json

3. Run the updater:

   cd tools/updater
   npm start
   

Build and test

Installs dependencies, runs validation tests and builds the wheel.

1. Install requirements:

   • Python
   • Poetry

2. Install dependencies:

   poetry install
   

3. Run tests (including official validation tests):

   poetry run pytest
   

4. Build Python wheel:

   poetry build