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import binascii
import serial
import struct
class AESession:
def __init__(self, link):
self.link = link
self.seq = 1
self.sendInit()
self.packetsize = 512
def recvMsg(self):
rawHeader = self.link.recv(12)
if len(rawHeader) != 12:
print('recvMsg: len(rawHeader) == ' + str(len(rawHeader)) + ' data: ' + binascii.hexlify(rawHeader))
#assert len(rawHeader) == 12
(type, datalen, seq, crc) = struct.unpack('!HHLL', rawHeader)
assert crc == (binascii.crc32(rawHeader[0:8]) & 0xffffffff)
# TODO: Send PkRs if CRC mismatches
data = b''
if datalen > 0:
data = self.link.recv(datalen)
assert len(data) == datalen
# Note: Python calculates signed CRCs.
# Thus, we parse the incoming CRC as signed.
datacrc = self.link.recv(4)
assert len(datacrc) == 4
(datacrc,) = struct.unpack('!L', datacrc)
assert datacrc == (binascii.crc32(data) & 0xffffffff)
# TODO: Send PkRs if CRC mismatches
self.link.send(b'PkOk')
# seq is currently ignored when receiving
return (type, data)
def sendMsg(self, type, data):
stream = struct.pack('!HHL', type, len(data), self.seq)
stream += struct.pack('!L', binascii.crc32(stream) & 0xffffffff)
if len(data) > 0:
stream += data
stream += struct.pack('!L', binascii.crc32(data) & 0xffffffff)
self.link.send(stream)
# TODO: Re-send on 'PkRs'
assert self.link.recv(4) == b'PkOk'
self.seq += 1;
def sendInit(self):
self.sendMsg(2, b'Cloanto(r)')
# TBD: Password support.
# It is CRC32'd and the CRC is appended to the string above.
# TODO: Recover from desynced state
#if not self.isAcked():
# self.sendAck()
# return self.sendInit()
(type, data) = self.recvMsg()
assert type == 2
assert data.startswith(b'Cloanto')
def sendClose(self):
print('sendClose')
self.sendMsg(0x6d, b'')
(type, data) = self.recvMsg()
assert type == 0x0a
if data != b'\0\0\0\0\0':
print('sendClose: data == ' + binascii.hexlify(data))
# Format of data returned:
# Byte 0: ?
# Byte 1: ?
# Byte 2: ?
# Byte 3: 00 - No error
# 06 - File no longer exists
# 1c - Timed out waiting for host to request next read block
# Byte 4: Path in case of error 06.
# Empty (null-terminated) otherwise?
# Null-terminated string.
#assert data == b'\0\0\0\0\0'
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