namehash.py

import sys
import codecs
import functools

from sha3 import sha3_256


if sys.version_info.major == 2:
    bytes_types = (bytes, bytearray)
    text_types = (unicode,)  # noqa: F821
else:
    bytes_types = (bytes, bytearray)
    text_types = (str,)


def is_bytes(value):
    return isinstance(value, bytes_types)


def is_text(value):
    return isinstance(value, text_types)


def force_bytes(value):
    if is_bytes(value):
        return bytes(value)
    elif is_text(value):
        return codecs.encode(value, "utf8")
    else:
        raise TypeError("Unsupported type: {0}".format(type(value)))


def identity(value):
    return value


def combine(f, g):
    return lambda x: f(g(x))


def compose(*functions):
    return functools.reduce(combine, reversed(functions), identity)


def sha3(value):
    return sha3_256(value).digest()


def _sub_hash(value, label):
    return sha3(value + sha3(label))


def namehash(name):
    node = b'\x00' * 32
    if name:
        labels = force_bytes(name).split(b'.')
        print(labels)
        return compose(*(
            functools.partial(_sub_hash, label=label)
            for label
            in reversed(labels)
        ))(node)
    return node


assert codecs.encode(namehash(''), 'hex') == b'0000000000000000000000000000000000000000000000000000000000000000'
assert codecs.encode(namehash('eth'), 'hex') == b'93cdeb708b7545dc668eb9280176169d1c33cfd8ed6f04690a0bcc88a93fc4ae'
assert codecs.encode(namehash('foo.eth'), 'hex') == b'de9b09fd7c5f901e23a3f19fecc54828e9c848539801e86591bd9801b019f84f'