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YModem.py
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YModem.py
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#! /usr/bin/env python
# -*- coding: utf-8 -*-
import os
import sys
import time
import math
import string
import logging
logging.basicConfig(level = logging.DEBUG, format = '%(asctime)s - %(levelname)s - %(message)s')
from YMTask import SendTask, ReceiveTask
# ymodem data header byte
SOH = b'\x01'
STX = b'\x02'
EOT = b'\x04'
ACK = b'\x06'
NAK = b'\x15'
CAN = b'\x18'
CRC = b'C'
class YModem(object):
def __init__(self, getc, putc, header_pad=b'\x00', data_pad=b'\x1a'):
self.getc = getc
self.putc = putc
self.st = SendTask()
self.rt = ReceiveTask()
self.header_pad = header_pad
self.data_pad = data_pad
self.log = logging.getLogger('YReporter')
def abort(self, count=2):
for _ in range(count):
self.putc(CAN)
def send_file(self, file_path, retry=20, callback=None):
try:
file_stream = open(file_path, 'rb')
file_name = os.path.basename(file_path)
file_size = os.path.getsize(file_path)
file_sent = self.send(file_stream, file_name, file_size, retry, callback)
except IOError as e:
self.log.error(str(e))
finally:
file_stream.close()
self.log.debug("Task Done!")
self.log.debug("File: " + file_name)
self.log.debug("Size: " + str(file_sent) + "Bytes")
self.log.debug("Packets: " + str(self.st.get_valid_sent_packets()))
return file_sent
def wait_for_next(self, ch):
cancel_count = 0
while True:
c = self.getc(1)
if c:
if c == ch:
self.log.debug("<<< " + hex(ord(ch)))
break
elif c == CAN:
if cancel_count == 2:
return -1
else:
cancel_count += 1
else:
self.log.warn("Expected " + hex(ord(ch)) + ", but got " + hex(ord(c)))
return 0
def send(self, data_stream, data_name, data_size, retry=20, callback=None):
packet_size = 1024
# [<<< CRC]
self.wait_for_next(CRC)
# [first packet >>>]
header = self._make_edge_packet_header()
if len(data_name) > 100:
data_name = data_name[:100]
self.st.set_task_name(data_name)
data_name += bytes.decode(self.header_pad)
data_size = str(data_size)
if len(data_size) > 20:
raise Exception("Data volume is too large!")
self.st.set_task_size(int(data_size))
data_size += bytes.decode(self.header_pad)
data = data_name + data_size
data = data.ljust(128, bytes.decode(self.header_pad))
checksum = self._make_send_checksum(data)
data_for_send = header + data.encode() + checksum
self.putc(data_for_send)
self.st.inc_sent_packets()
# data_in_hexstring = "".join("%02x" % b for b in data_for_send)
self.log.debug("Packet 0 >>>")
# [<<< ACK]
# [<<< CRC]
self.wait_for_next(ACK)
self.wait_for_next(CRC)
# [data packet >>>]
# [<<< ACK]
error_count = 0
sequence = 1
while True:
data = data_stream.read(packet_size)
if not data:
self.log.debug('EOF')
break
extracted_data_bytes = len(data)
if extracted_data_bytes <= 128:
packet_size = 128
header = self._make_data_packet_header(packet_size, sequence)
data = data.ljust(packet_size, self.data_pad)
checksum = self._make_send_checksum(data)
data_for_send = header + data + checksum
# data_in_hexstring = "".join("%02x" % b for b in data_for_send)
while True:
self.putc(data_for_send)
self.st.inc_sent_packets()
self.log.debug("Packet " + str(sequence) + " >>>")
c = self.getc(1)
if c == ACK:
self.log.debug("<<< ACK")
self.st.inc_valid_sent_packets()
self.st.add_valid_sent_bytes(extracted_data_bytes)
error_count = 0
break
else:
error_count += 1
self.st.inc_missing_sent_packets()
self.log.debug("RETRY " + str(error_count))
if error_count > retry:
self.abort()
self.log.error('send error: NAK received %d , aborting', retry)
return -2
sequence = (sequence + 1) % 0x100
# [EOT >>>]
# [<<< ACK]
# [EOT >>>]
# [<<< ACK]
self.putc(EOT)
self.log.debug(">>> EOT")
self.wait_for_next(ACK)
self.putc(EOT)
self.log.debug(">>> EOT")
self.wait_for_next(ACK)
# [<<< CRC]
self.wait_for_next(CRC)
# [Final packet >>>]
header = self._make_edge_packet_header()
data = "".ljust(128, bytes.decode(self.header_pad))
checksum = self._make_send_checksum(data)
data_for_send = header + data.encode() + checksum
self.putc(data_for_send)
self.st.inc_sent_packets()
self.log.debug("Packet End >>>")
#self.wait_for_next(ACK)
return self.st.get_valid_sent_bytes()
def wait_for_header(self):
cancel_count = 0
while True:
c = self.getc(1)
if c:
if c == SOH or c == STX:
return c
elif c == CAN:
if cancel_count == 2:
return -1
else:
cancel_count += 1
else:
self.log.warn("Expected 0x01(SOH)/0x02(STX)/0x18(CAN), but got " + hex(ord(c)))
def wait_for_eot(self):
eot_count = 0
while True:
c = self.getc(1)
if c:
if c == EOT:
eot_count += 1
if eot_count == 1:
self.log.debug("EOT >>>")
self.putc(NAK)
self.log.debug("<<< NAK")
elif eot_count == 2:
self.log.debug("EOT >>>")
self.putc(ACK)
self.log.debug("<<< ACK")
self.putc(CRC)
self.log.debug("<<< CRC")
break
else:
self.log.warn("Expected 0x04(EOT), but got " + hex(ord(c)))
def recv_file(self, root_path, callback=None):
while True:
self.putc(CRC)
self.log.debug("<<< CRC")
c = self.getc(1)
if c:
if c == SOH:
packet_size = 128
break
elif c == STX:
packet_size = 1024
break
else:
self.log.warn("Expected 0x01(SOH)/0x02(STX)/0x18(CAN), but got " + hex(ord(c)))
IS_FIRST_PACKET = True
FIRST_PACKET_RECEIVED = False
WAIT_FOR_EOT = False
WAIT_FOR_END_PACKET = False
sequence = 0
while True:
if WAIT_FOR_EOT:
self.wait_for_eot()
WAIT_FOR_EOT = False
WAIT_FOR_END_PACKET = True
sequence = 0
else:
if IS_FIRST_PACKET:
IS_FIRST_PACKET = False
else:
c = self.wait_for_header()
if c == SOH:
packet_size = 128
elif c == STX:
packet_size = 1024
else:
return c
seq = self.getc(1)
if seq is None:
seq_oc = None
else:
seq = ord(seq)
c = self.getc(1)
if c is not None:
seq_oc = 0xFF - ord(c)
data = self.getc(packet_size + 2)
if not (seq == seq_oc == sequence):
continue
else:
valid, _ = self._verify_recv_checksum(data)
if valid:
# first packet
# [<<< ACK]
# [<<< CRC]
if seq == 0 and not FIRST_PACKET_RECEIVED and not WAIT_FOR_END_PACKET:
self.log.debug("Packet 0 >>>")
self.putc(ACK)
self.log.debug("<<< ACK")
self.putc(CRC)
self.log.debug("<<< CRC")
file_name_bytes, data_size_bytes = (data[:-2]).rstrip(self.header_pad).split(self.header_pad)
file_name = bytes.decode(file_name_bytes)
data_size = bytes.decode(data_size_bytes)
self.log.debug("TASK: " + file_name + " " + data_size + "Bytes")
self.rt.set_task_name(file_name)
self.rt.set_task_size(int(data_size))
file_stream = open(os.path.join(root_path, file_name), 'wb+')
FIRST_PACKET_RECEIVED = True
sequence = (sequence + 1) % 0x100
# data packet
# [data packet >>>]
# [<<< ACK]
elif not WAIT_FOR_END_PACKET:
self.rt.inc_valid_received_packets()
self.log.debug("Packet " + str(sequence) + " >>>")
valid_data = data[:-2]
# last data packet
if self.rt.get_valid_received_packets() == self.rt.get_task_packets():
valid_data = valid_data[:self.rt.get_last_valid_packet_size()]
WAIT_FOR_EOT = True
self.rt.add_valid_received_bytes(len(valid_data))
file_stream.write(valid_data)
self.putc(ACK)
self.log.debug("<<< ACK")
sequence = (sequence + 1) % 0x100
# final packet
# [<<< ACK]
else:
self.log.debug("Packet End >>>")
self.putc(ACK)
self.log.debug("<<< ACK")
break
file_stream.close()
self.log.debug("Task Done!")
self.log.debug("File: " + self.rt.get_task_name())
self.log.debug("Size: " + str(self.rt.get_task_size()) + "Bytes")
self.log.debug("Packets: " + str(self.rt.get_valid_received_packets()))
return self.rt.get_valid_received_bytes()
# Header byte
def _make_edge_packet_header(self):
_bytes = [ord(SOH), 0, 0xff]
return bytearray(_bytes)
def _make_data_packet_header(self, packet_size, sequence):
assert packet_size in (128, 1024), packet_size
_bytes = []
if packet_size == 128:
_bytes.append(ord(SOH))
elif packet_size == 1024:
_bytes.append(ord(STX))
_bytes.extend([sequence, 0xff - sequence])
return bytearray(_bytes)
# Make check code
def _make_send_checksum(self, data):
_bytes = []
crc = self.calc_crc(data)
_bytes.extend([crc >> 8, crc & 0xff])
return bytearray(_bytes)
def _verify_recv_checksum(self, data):
_checksum = bytearray(data[-2:])
their_sum = (_checksum[0] << 8) + _checksum[1]
data = data[:-2]
our_sum = self.calc_crc(data)
valid = bool(their_sum == our_sum)
return valid, data
# For CRC algorithm
crctable = [
0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0,
]
# CRC algorithm: CCITT-0
def calc_crc(self, data, crc=0):
if isinstance(data, str):
ba = bytearray(data, 'utf-8')
else:
ba = bytearray(data)
for char in ba:
crctbl_idx = ((crc >> 8) ^ char) & 0xff
crc = ((crc << 8) ^ self.crctable[crctbl_idx]) & 0xffff
return crc & 0xffff
if __name__ == '__main__':
pass