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Code Issues Releases Wiki Activity

fixes for latest V2 format, add checksum

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This commit is contained in:
Jan Pochyla 2016-08-05 13:11:24 +02:00
parent 8bb7f550ad
commit e9427b04f3
1 changed files with 27 additions and 15 deletions
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42
trezorlib/transport.py
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@ -162,21 +162,27 @@ class TransportV2(Transport):
def write(self, msg):
data = bytearray(msg.SerializeToString())
# Convert to unsigned in python2
checksum = 0 # binascii.crc32(data) & 0xffffffff
header1 = struct.pack(">L", self.session_id)
header2 = struct.pack(">LL", mapping.get_type(msg), len(data))
footer = struct.pack(">L", checksum)
data = header2 + data
data = header2 + data + footer
first = True
while len(data):
if first:
# Magic characters, header1, header2, data padded to 64 bytes
datalen = 62 - len(header1)
chunk = b'?!' + header1 + data[:datalen] + b'\0' * (datalen - len(data[:datalen]))
else:
# Magic characters, header1, data padded to 64 bytes
# Magic character, header1, header2, data padded to 64 bytes
datalen = 63 - len(header1)
chunk = b'?' + header1 + data[:datalen] + b'\0' * (datalen - len(data[:datalen]))
chunk = b'!' + header1 + \
data[:datalen] + b'\0' * (datalen - len(data[:datalen]))
else:
# Magic character, header1, data padded to 64 bytes
datalen = 63 - len(header1)
chunk = b'#' + header1 + \
data[:datalen] + b'\0' * (datalen - len(data[:datalen]))
self._write_chunk(chunk)
data = data[datalen:]
@ -185,8 +191,9 @@ class TransportV2(Transport):
def _read(self):
chunk = self._read_chunk()
(session_id, msg_type, datalen, data) = self.parse_first(chunk)
payloadlen = datalen + 4 # For the checksum
while len(data) < datalen:
while len(data) < payloadlen:
chunk = self._read_chunk()
(next_session_id, next_data) = self.parse_next(chunk)
@ -195,25 +202,30 @@ class TransportV2(Transport):
data.extend(next_data)
# Strip padding zeros
data = data[:datalen]
data = data[:payloadlen] # Strip padding zeros
footer = data[-4:]
data = data[:-4]
# csum = struct.unpack('>L', footer)
# assert csum == binascii.crc32(data), "Checksum mismatch"
return (session_id, msg_type, data)
def parse_first(self, chunk):
if chunk[:2] != b"?!":
raise Exception("Unexpected magic characters")
if chunk[0:1] != b"!":
raise Exception("Unexpected magic character")
try:
headerlen = struct.calcsize(">LLL")
(session_id, msg_type, datalen) = struct.unpack(">LLL", bytes(chunk[2:2 + headerlen]))
(session_id, msg_type, datalen) = struct.unpack(">LLL", bytes(chunk[1:1 + headerlen]))
except:
raise Exception("Cannot parse header")
data = chunk[2 + headerlen:]
data = chunk[1 + headerlen:]
return (session_id, msg_type, datalen, data)
def parse_next(self, chunk):
if chunk[0:1] != b"?":
if chunk[0:1] != b"#":
raise Exception("Unexpected magic characters")
try: