mirror of
https://github.com/trezor/trezor-firmware.git
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afb3e04c24
This makes more sense, because bytes are immutable and callers have no business mutating structures from the wire anyway. Incidentally this should fix issue #236, where rlp library would treat bytes and bytearrays differently and produce invalid structures in our usecase. Also very minor nitpicks and code cleanup for neater typing.
320 lines
8.1 KiB
Python
320 lines
8.1 KiB
Python
# This file is part of the TREZOR project.
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#
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# Copyright (C) 2012-2016 Marek Palatinus <slush@satoshilabs.com>
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# Copyright (C) 2012-2016 Pavol Rusnak <stick@satoshilabs.com>
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#
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# This library is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public License
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# along with this library. If not, see <http://www.gnu.org/licenses/>.
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'''
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Extremely minimal streaming codec for a subset of protobuf. Supports uint32,
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bytes, string, embedded message and repeated fields.
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For de-sererializing (loading) protobuf types, object with `Reader`
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interface is required:
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>>> class Reader:
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>>> def readinto(self, buffer):
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>>> """
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>>> Reads `len(buffer)` bytes into `buffer`, or raises `EOFError`.
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>>> """
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For serializing (dumping) protobuf types, object with `Writer` interface is
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required:
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>>> class Writer:
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>>> def write(self, buffer):
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>>> """
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>>> Writes all bytes from `buffer`, or raises `EOFError`.
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>>> """
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'''
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from io import BytesIO
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_UVARINT_BUFFER = bytearray(1)
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def load_uvarint(reader):
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buffer = _UVARINT_BUFFER
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result = 0
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shift = 0
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byte = 0x80
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while byte & 0x80:
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if reader.readinto(buffer) == 0:
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raise EOFError
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byte = buffer[0]
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result += (byte & 0x7F) << shift
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shift += 7
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return result
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def dump_uvarint(writer, n):
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buffer = _UVARINT_BUFFER
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shifted = True
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while shifted:
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shifted = n >> 7
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buffer[0] = (n & 0x7F) | (0x80 if shifted else 0x00)
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writer.write(buffer)
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n = shifted
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class UVarintType:
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WIRE_TYPE = 0
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class Sint32Type:
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WIRE_TYPE = 0
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class Sint64Type:
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WIRE_TYPE = 0
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class BoolType:
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WIRE_TYPE = 0
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class BytesType:
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WIRE_TYPE = 2
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class UnicodeType:
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WIRE_TYPE = 2
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class MessageType:
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WIRE_TYPE = 2
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FIELDS = {}
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def __init__(self, **kwargs):
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for kw in kwargs:
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setattr(self, kw, kwargs[kw])
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self._fill_missing()
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def __eq__(self, rhs):
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return (self.__class__ is rhs.__class__ and
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self.__dict__ == rhs.__dict__)
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def __repr__(self):
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d = {}
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for key, value in self.__dict__.items():
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if value is None or value == []:
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continue
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d[key] = value
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return '<%s: %s>' % (self.__class__.__name__, d)
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def __iter__(self):
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return self.__dict__.__iter__()
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def __getattr__(self, attr):
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if attr.startswith('_add_'):
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return self._additem(attr[5:])
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if attr.startswith('_extend_'):
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return self._extenditem(attr[8:])
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raise AttributeError(attr)
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def _extenditem(self, attr):
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def f(param):
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try:
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l = getattr(self, attr)
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except AttributeError:
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l = []
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setattr(self, attr, l)
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l += param
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return f
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def _additem(self, attr):
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# Add new item for repeated field type
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for v in self.FIELDS.values():
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if v[0] != attr:
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continue
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if not (v[2] & FLAG_REPEATED):
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raise AttributeError
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try:
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l = getattr(self, v[0])
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except AttributeError:
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l = []
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setattr(self, v[0], l)
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item = v[1]()
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l.append(item)
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return lambda: item
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raise AttributeError
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def _fill_missing(self):
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# fill missing fields
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for fname, ftype, fflags in self.FIELDS.values():
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if not hasattr(self, fname):
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if fflags & FLAG_REPEATED:
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setattr(self, fname, [])
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else:
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setattr(self, fname, None)
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def CopyFrom(self, obj):
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self.__dict__ = obj.__dict__.copy()
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def ByteSize(self):
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data = BytesIO()
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dump_message(data, self)
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return len(data.getvalue())
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class LimitedReader:
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def __init__(self, reader, limit):
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self.reader = reader
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self.limit = limit
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def readinto(self, buf):
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if self.limit < len(buf):
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raise EOFError
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else:
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nread = self.reader.readinto(buf)
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self.limit -= nread
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return nread
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class CountingWriter:
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def __init__(self):
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self.size = 0
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def write(self, buf):
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nwritten = len(buf)
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self.size += nwritten
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return nwritten
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FLAG_REPEATED = 1
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def load_message(reader, msg_type):
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fields = msg_type.FIELDS
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msg = msg_type()
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while True:
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try:
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fkey = load_uvarint(reader)
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except EOFError:
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break # no more fields to load
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ftag = fkey >> 3
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wtype = fkey & 7
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field = fields.get(ftag, None)
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if field is None: # unknown field, skip it
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if wtype == 0:
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load_uvarint(reader)
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elif wtype == 2:
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ivalue = load_uvarint(reader)
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reader.readinto(bytearray(ivalue))
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else:
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raise ValueError
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continue
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fname, ftype, fflags = field
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if wtype != ftype.WIRE_TYPE:
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raise TypeError # parsed wire type differs from the schema
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ivalue = load_uvarint(reader)
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if ftype is UVarintType:
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fvalue = ivalue
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elif ftype is Sint32Type:
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fvalue = (ivalue >> 1) ^ ((ivalue << 31) & 0xffffffff)
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elif ftype is Sint64Type:
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fvalue = (ivalue >> 1) ^ ((ivalue << 63) & 0xffffffffffffffff)
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elif ftype is BoolType:
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fvalue = bool(ivalue)
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elif ftype is BytesType:
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buf = bytearray(ivalue)
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reader.readinto(buf)
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fvalue = bytes(buf)
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elif ftype is UnicodeType:
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buf = bytearray(ivalue)
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reader.readinto(buf)
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fvalue = buf.decode()
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elif issubclass(ftype, MessageType):
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fvalue = load_message(LimitedReader(reader, ivalue), ftype)
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else:
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raise TypeError # field type is unknown
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if fflags & FLAG_REPEATED:
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pvalue = getattr(msg, fname)
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pvalue.append(fvalue)
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fvalue = pvalue
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setattr(msg, fname, fvalue)
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return msg
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def dump_message(writer, msg):
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repvalue = [0]
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mtype = msg.__class__
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fields = mtype.FIELDS
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for ftag in fields:
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fname, ftype, fflags = fields[ftag]
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fvalue = getattr(msg, fname, None)
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if fvalue is None:
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continue
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fkey = (ftag << 3) | ftype.WIRE_TYPE
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if not fflags & FLAG_REPEATED:
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repvalue[0] = fvalue
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fvalue = repvalue
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for svalue in fvalue:
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dump_uvarint(writer, fkey)
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if ftype is UVarintType:
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dump_uvarint(writer, svalue)
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elif ftype is Sint32Type:
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dump_uvarint(writer, ((svalue << 1) & 0xffffffff) ^ (svalue >> 31))
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elif ftype is Sint64Type:
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dump_uvarint(writer, ((svalue << 1) & 0xffffffffffffffff) ^ (svalue >> 63))
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elif ftype is BoolType:
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dump_uvarint(writer, int(svalue))
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elif ftype is BytesType:
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dump_uvarint(writer, len(svalue))
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writer.write(svalue)
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elif ftype is UnicodeType:
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if not isinstance(svalue, bytes):
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svalue = svalue.encode('utf-8')
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dump_uvarint(writer, len(svalue))
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writer.write(svalue)
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elif issubclass(ftype, MessageType):
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counter = CountingWriter()
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dump_message(counter, svalue)
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dump_uvarint(writer, counter.size)
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dump_message(writer, svalue)
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else:
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raise TypeError
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