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chore(core): Use BufferReader for CBOR decoding.
This commit is contained in:
Andrew Kozlik
Andrew Kozlik
parent
ac939c94aa
commit
e5741ac308
@ -5,7 +5,9 @@ Minimalistic CBOR implementation, supports only what we need in cardano.
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import ustruct as struct
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from micropython import const
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from trezor import log
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from trezor import log, utils
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from . import readers
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if False:
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from typing import Any, Iterable, List, Tuple, Union
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@ -103,110 +105,93 @@ def _cbor_encode(value: Value) -> Iterable[bytes]:
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raise NotImplementedError
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def _read_length(cbor: bytes, aux: int) -> Tuple[int, bytes]:
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def _read_length(r: utils.BufferReader, aux: int) -> int:
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if aux < _CBOR_UINT8_FOLLOWS:
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return (aux, cbor)
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return aux
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elif aux == _CBOR_UINT8_FOLLOWS:
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return (cbor[0], cbor[1:])
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return r.get()
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elif aux == _CBOR_UINT16_FOLLOWS:
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res = cbor[1]
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res += cbor[0] << 8
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return (res, cbor[2:])
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return readers.read_uint16_be(r)
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elif aux == _CBOR_UINT32_FOLLOWS:
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res = cbor[3]
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res += cbor[2] << 8
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res += cbor[1] << 16
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res += cbor[0] << 24
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return (res, cbor[4:])
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return readers.read_uint32_be(r)
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elif aux == _CBOR_UINT64_FOLLOWS:
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res = cbor[7]
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res += cbor[6] << 8
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res += cbor[5] << 16
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res += cbor[4] << 24
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res += cbor[3] << 32
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res += cbor[2] << 40
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res += cbor[1] << 48
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res += cbor[0] << 56
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return (res, cbor[8:])
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return readers.read_uint64_be(r)
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else:
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raise NotImplementedError("Length %d not suppported" % aux)
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def _cbor_decode(cbor: bytes) -> Tuple[Value, bytes]:
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fb = cbor[0]
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data = b""
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def _cbor_decode(r: utils.BufferReader) -> Value:
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fb = r.get()
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fb_type = fb & _CBOR_TYPE_MASK
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fb_aux = fb & _CBOR_INFO_BITS
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if fb_type == _CBOR_UNSIGNED_INT:
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return _read_length(cbor[1:], fb_aux)
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return _read_length(r, fb_aux)
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elif fb_type == _CBOR_NEGATIVE_INT:
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val, data = _read_length(cbor[1:], fb_aux)
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return (-1 - val, data)
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val = _read_length(r, fb_aux)
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return -1 - val
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elif fb_type == _CBOR_BYTE_STRING:
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ln, data = _read_length(cbor[1:], fb_aux)
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return (data[0:ln], data[ln:])
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ln = _read_length(r, fb_aux)
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return r.read(ln)
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elif fb_type == _CBOR_TEXT_STRING:
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ln, data = _read_length(cbor[1:], fb_aux)
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return (data[0:ln].decode(), data[ln:])
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ln = _read_length(r, fb_aux)
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return r.read(ln).decode()
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elif fb_type == _CBOR_ARRAY:
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if fb_aux == _CBOR_VAR_FOLLOWS:
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res: Value = []
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data = cbor[1:]
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while True:
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item, data = _cbor_decode(data)
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item = _cbor_decode(r)
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if item == _CBOR_PRIMITIVE + _CBOR_BREAK:
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break
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res.append(item)
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return (res, data)
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return res
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else:
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ln, data = _read_length(cbor[1:], fb_aux)
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ln = _read_length(r, fb_aux)
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res = []
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for i in range(ln):
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item, data = _cbor_decode(data)
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for _ in range(ln):
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item = _cbor_decode(r)
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res.append(item)
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return (res, data)
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return res
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elif fb_type == _CBOR_MAP:
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res = {}
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if fb_aux == _CBOR_VAR_FOLLOWS:
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data = cbor[1:]
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while True:
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key, data = _cbor_decode(data)
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key = _cbor_decode(r)
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if key in res:
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raise ValueError
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if key == _CBOR_PRIMITIVE + _CBOR_BREAK:
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break
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value, data = _cbor_decode(data)
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value = _cbor_decode(r)
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res[key] = value
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else:
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ln, data = _read_length(cbor[1:], fb_aux)
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for i in range(ln):
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key, data = _cbor_decode(data)
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ln = _read_length(r, fb_aux)
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for _ in range(ln):
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key = _cbor_decode(r)
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if key in res:
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raise ValueError
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value, data = _cbor_decode(data)
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value = _cbor_decode(r)
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res[key] = value
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return res, data
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return res
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elif fb_type == _CBOR_TAG:
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val, data = _read_length(cbor[1:], fb_aux)
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item, data = _cbor_decode(data)
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val = _read_length(r, fb_aux)
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item = _cbor_decode(r)
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if val == _CBOR_RAW_TAG: # only tag 24 (0x18) is supported
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return item, data
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return item
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else:
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return Tagged(val, item), data
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return Tagged(val, item)
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elif fb_type == _CBOR_PRIMITIVE:
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if fb_aux == _CBOR_FALSE:
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return (False, cbor[1:])
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return False
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elif fb_aux == _CBOR_TRUE:
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return (True, cbor[1:])
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return True
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elif fb_aux == _CBOR_NULL:
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return (None, cbor[1:])
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return None
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elif fb_aux == _CBOR_BREAK:
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return (cbor[0], cbor[1:])
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return fb
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else:
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raise NotImplementedError
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else:
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if __debug__:
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log.debug(__name__, "not implemented (decode): %s", cbor[0])
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log.debug(__name__, "not implemented (decode): %s", fb)
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raise NotImplementedError
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@ -246,7 +231,8 @@ def encode(value: Value) -> bytes:
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def decode(cbor: bytes) -> Value:
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res, check = _cbor_decode(cbor)
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if not (check == b""):
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r = utils.BufferReader(cbor)
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res = _cbor_decode(r)
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if r.remaining_count():
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raise ValueError
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return res
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@ -18,9 +18,20 @@ def read_bitcoin_varint(r: BufferReader) -> int:
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return n
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def read_uint16_be(r: BufferReader) -> int:
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n = r.get()
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return (n << 8) + r.get()
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def read_uint32_be(r: BufferReader) -> int:
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n = r.get() << 24
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n += r.get() << 16
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n += r.get() << 8
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n += r.get()
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n = r.get()
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for _ in range(3):
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n = (n << 8) + r.get()
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return n
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def read_uint64_be(r: BufferReader) -> int:
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n = r.get()
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for _ in range(7):
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n = (n << 8) + r.get()
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return n
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@ -69,9 +69,10 @@ class TestCardanoCbor(unittest.TestCase):
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# null
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(None, 'f6'),
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]
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for val, encoded in test_vectors:
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self.assertEqual(unhexlify(encoded), encode(val))
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self.assertEqual(val, decode(unhexlify(encoded)))
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for val, encoded_hex in test_vectors:
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encoded = unhexlify(encoded_hex)
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self.assertEqual(encode(val), encoded)
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self.assertEqual(decode(encoded), val)
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def test_cbor_tuples(self):
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"""
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@ -83,10 +84,11 @@ class TestCardanoCbor(unittest.TestCase):
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([1, [2, 3], [4, 5]], '8301820203820405'),
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(list(range(1, 26)), '98190102030405060708090a0b0c0d0e0f101112131415161718181819'),
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]
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for val, encoded in test_vectors:
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for val, encoded_hex in test_vectors:
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value_tuple = tuple(val)
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self.assertEqual(unhexlify(encoded), encode(value_tuple))
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self.assertEqual(val, decode(unhexlify(encoded)))
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encoded = unhexlify(encoded_hex)
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self.assertEqual(encode(value_tuple), encoded)
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self.assertEqual(decode(encoded), val)
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if __name__ == '__main__':
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unittest.main()
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