trezor-firmware/trezorlib/tools.py

# This file is part of the Trezor project.
#
# Copyright (C) 2012-2018 SatoshiLabs and contributors
#
# This library is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License version 3
# as published by the Free Software Foundation.
#
# This library 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 Lesser General Public License for more details.
#
# You should have received a copy of the License along with this library.
# If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.

import functools
import hashlib
import re
import struct
import unicodedata
from typing import List, NewType

from .coins import slip44
from .exceptions import TrezorException

CallException = TrezorException

HARDENED_FLAG = 1 << 31

Address = NewType("Address", List[int])


def H_(x: int) -> int:
    """
    Shortcut function that "hardens" a number in a BIP44 path.
    """
    return x | HARDENED_FLAG


def btc_hash(data):
    """
    Double-SHA256 hash as used in BTC
    """
    return hashlib.sha256(hashlib.sha256(data).digest()).digest()


def hash_160(public_key):
    md = hashlib.new("ripemd160")
    md.update(hashlib.sha256(public_key).digest())
    return md.digest()


def hash_160_to_bc_address(h160, address_type):
    vh160 = struct.pack("<B", address_type) + h160
    h = btc_hash(vh160)
    addr = vh160 + h[0:4]
    return b58encode(addr)


def compress_pubkey(public_key):
    if public_key[0] == 4:
        return bytes((public_key[64] & 1) + 2) + public_key[1:33]
    raise ValueError("Pubkey is already compressed")


def public_key_to_bc_address(public_key, address_type, compress=True):
    if public_key[0] == "\x04" and compress:
        public_key = compress_pubkey(public_key)

    h160 = hash_160(public_key)
    return hash_160_to_bc_address(h160, address_type)


__b58chars = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
__b58base = len(__b58chars)


def b58encode(v):
    """ encode v, which is a string of bytes, to base58."""

    long_value = 0
    for c in v:
        long_value = long_value * 256 + c

    result = ""
    while long_value >= __b58base:
        div, mod = divmod(long_value, __b58base)
        result = __b58chars[mod] + result
        long_value = div
    result = __b58chars[long_value] + result

    # Bitcoin does a little leading-zero-compression:
    # leading 0-bytes in the input become leading-1s
    nPad = 0
    for c in v:
        if c == 0:
            nPad += 1
        else:
            break

    return (__b58chars[0] * nPad) + result


def b58decode(v, length=None):
    """ decode v into a string of len bytes."""
    if isinstance(v, bytes):
        v = v.decode()

    long_value = 0
    for (i, c) in enumerate(v[::-1]):
        long_value += __b58chars.find(c) * (__b58base ** i)

    result = b""
    while long_value >= 256:
        div, mod = divmod(long_value, 256)
        result = struct.pack("B", mod) + result
        long_value = div
    result = struct.pack("B", long_value) + result

    nPad = 0
    for c in v:
        if c == __b58chars[0]:
            nPad += 1
        else:
            break

    result = b"\x00" * nPad + result
    if length is not None and len(result) != length:
        return None

    return result


def b58check_encode(v):
    checksum = btc_hash(v)[:4]
    return b58encode(v + checksum)


def b58check_decode(v, length=None):
    dec = b58decode(v, length)
    data, checksum = dec[:-4], dec[-4:]
    if btc_hash(data)[:4] != checksum:
        raise ValueError("invalid checksum")
    return data


def parse_path(nstr: str) -> Address:
    """
    Convert BIP32 path string to list of uint32 integers with hardened flags.
    Several conventions are supported to set the hardened flag: -1, 1', 1h

    e.g.: "0/1h/1" -> [0, 0x80000001, 1]

    :param nstr: path string
    :return: list of integers
    """
    if not nstr:
        return []

    n = nstr.split("/")

    # m/a/b/c => a/b/c
    if n[0] == "m":
        n = n[1:]

    # coin_name/a/b/c => 44'/SLIP44_constant'/a/b/c
    if n[0] in slip44:
        coin_id = slip44[n[0]]
        n[0:1] = ["44h", "{}h".format(coin_id)]

    def str_to_harden(x: str) -> int:
        if x.startswith("-"):
            return H_(abs(int(x)))
        elif x.endswith(("h", "'")):
            return H_(int(x[:-1]))
        else:
            return int(x)

    try:
        return [str_to_harden(x) for x in n]
    except Exception:
        raise ValueError("Invalid BIP32 path", nstr)


def normalize_nfc(txt):
    """
    Normalize message to NFC and return bytes suitable for protobuf.
    This seems to be bitcoin-qt standard of doing things.
    """
    if isinstance(txt, bytes):
        txt = txt.decode()
    return unicodedata.normalize("NFC", txt).encode()


class expect:
    # Decorator checks if the method
    # returned one of expected protobuf messages
    # or raises an exception
    def __init__(self, expected, field=None):
        self.expected = expected
        self.field = field

    def __call__(self, f):
        @functools.wraps(f)
        def wrapped_f(*args, **kwargs):
            __tracebackhide__ = True  # for pytest # pylint: disable=W0612
            ret = f(*args, **kwargs)
            if not isinstance(ret, self.expected):
                raise RuntimeError(
                    "Got %s, expected %s" % (ret.__class__, self.expected)
                )
            if self.field is not None:
                return getattr(ret, self.field)
            else:
                return ret

        return wrapped_f


def session(f):
    # Decorator wraps a BaseClient method
    # with session activation / deactivation
    @functools.wraps(f)
    def wrapped_f(client, *args, **kwargs):
        __tracebackhide__ = True  # for pytest # pylint: disable=W0612
        client.transport.begin_session()
        try:
            return f(client, *args, **kwargs)
        finally:
            client.transport.begin_session()

    return wrapped_f


# de-camelcasifier
# https://stackoverflow.com/a/1176023/222189

FIRST_CAP_RE = re.compile("(.)([A-Z][a-z]+)")
ALL_CAP_RE = re.compile("([a-z0-9])([A-Z])")


def from_camelcase(s):
    s = FIRST_CAP_RE.sub(r"\1_\2", s)
    return ALL_CAP_RE.sub(r"\1_\2", s).lower()


def dict_from_camelcase(d, renames=None):
    if not isinstance(d, dict):
        return d

    if renames is None:
        renames = {}

    res = {}
    for key, value in d.items():
        newkey = from_camelcase(key)
        renamed_key = renames.get(newkey) or renames.get(key)
        if renamed_key:
            newkey = renamed_key

        if isinstance(value, list):
            res[newkey] = [dict_from_camelcase(v, renames) for v in value]
        else:
            res[newkey] = dict_from_camelcase(value, renames)

    return res