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Tidied up the ymodem implementation, as we are only testing sending a single file at a time and no attempt is being made to keep compatibility with other *modem implmentations slimmed it down to code that is actually in use.

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This commit is contained in:
Adam Boardman 2020-12-17 14:34:34 +00:00
parent fe385178b7
commit afcfde4b7b
2 changed files with 54 additions and 358 deletions
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2
codi-app/codiUpdate.py
View file

@ -135,7 +135,7 @@ def send_file(file):
print("Sending", file)
try:
print("Send completed:", modem.send([file], callback=callback))
print("Send completed:", modem.send(file, callback=callback))
except Exception as e:
print("Exception", e)
SerialPortManager.switchToCmdMode()

410
codi-app/xmodem/__init__.py
View file

@ -1,87 +1,19 @@
'''
===============================
XMODEM file transfer protocol
===============================
=======================================
Modified YMODEM file transfer protocol
=======================================
.. $Id$
This is a literal implementation of XMODEM.TXT_, XMODEM1K.TXT_ and
XMODMCRC.TXT_, support for YMODEM and ZMODEM is pending. YMODEM should
be fairly easy to implement as it is a hack on top of the XMODEM
protocol using sequence bytes ``0x00`` for sending file names (and some
meta data).
This is a implementation of YMODEM as used on the Cosmo Communicator.
.. _XMODEM.TXT: doc/XMODEM.TXT
.. _XMODEM1K.TXT: doc/XMODEM1K.TXT
.. _XMODMCRC.TXT: doc/XMODMCRC.TXT
Data flow example including error recovery
==========================================
Data flow example
=================
Here is a sample of the data flow, sending a 3-block message.
It includes the two most common line hits - a garbaged block,
and an ``ACK`` reply getting garbaged. ``CRC`` or ``CSUM`` represents
the checksum bytes.
XMODEM 128 byte blocks
----------------------
::
SENDER RECEIVER
<-- NAK
SOH 01 FE Data[128] CSUM -->
<-- ACK
SOH 02 FD Data[128] CSUM -->
<-- ACK
SOH 03 FC Data[128] CSUM -->
<-- ACK
SOH 04 FB Data[128] CSUM -->
<-- ACK
SOH 05 FA Data[100] CPMEOF[28] CSUM -->
<-- ACK
EOT -->
<-- ACK
XMODEM-1k blocks, CRC mode
--------------------------
::
SENDER RECEIVER
<-- C
STX 01 FE Data[1024] CRC CRC -->
<-- ACK
STX 02 FD Data[1024] CRC CRC -->
<-- ACK
STX 03 FC Data[1000] CPMEOF[24] CRC CRC -->
<-- ACK
EOT -->
<-- ACK
Mixed 1024 and 128 byte Blocks
------------------------------
::
SENDER RECEIVER
<-- C
STX 01 FE Data[1024] CRC CRC -->
<-- ACK
STX 02 FD Data[1024] CRC CRC -->
<-- ACK
SOH 03 FC Data[128] CRC CRC -->
<-- ACK
SOH 04 FB Data[100] CPMEOF[28] CRC CRC -->
<-- ACK
EOT -->
<-- ACK
YMODEM Batch Transmission Session (1 file)
------------------------------------------
Batch Transmission Session (1 file - not tested with more than one)
-------------------------------------------------------------------
::
@ -89,21 +21,37 @@ YMODEM Batch Transmission Session (1 file)
<-- C (command:rb)
SOH 00 FF foo.c NUL[123] CRC CRC -->
<-- ACK
SOH 01 FE Data[1024] CRC CRC --> (probably received garbled)
<-- C
SOH 01 FE Data[128] CRC CRC -->
SOH 01 FE Data[1024] CRC CRC (resend) --> (starts flash erase)
<-- (empty read timed out)
<-- (empty read timed out)
<-- (empty read timed out)
<-- C
SOH 01 FE Data[1024] CRC CRC (resend) -->
<-- ACK
SOH 02 FC Data[128] CRC CRC -->
SOH 02 FC Data[1024] CRC CRC --> (probably received garbled)
<-- C
SOH 02 FC Data[1024] CRC CRC (resend) -->
<-- ACK
SOH 03 FB Data[100] CPMEOF[28] CRC CRC -->
SOH 03 FB Data[1000] CPMEOF[24] CRC CRC -->
<-- ACK
EOT -->
<-- NAK
EOT -->
EOT -->
<-- C
EOT -->
EOT -->
EOT -->
<-- C
EOT -->
EOT -->
EOT -->
<-- C
EOT -->
EOT -->
EOT -->
<-- ACK
<-- C
SOH 00 FF NUL[128] CRC CRC -->
<-- ACK
'''
from __future__ import division, print_function
@ -119,7 +67,7 @@ import platform
import logging
import time
import sys
from functools import partial
import os
# Protocol bytes
NUL = b'\x00'
@ -137,22 +85,21 @@ CRC2 = b'\xc3'
CRC3 = b'\x83'
ABT = b'a' #0x61 - flash fail - abort
class XMODEM(object):
class YMODEM(object):
'''
XMODEM Protocol handler, expects two callables which encapsulate the read
YMODEM Protocol handler, expects two callables which encapsulate the read
and write operations on the underlying stream.
Example functions for reading and writing to a serial line:
>>> import serial
>>> from xmodem import XMODEM
>>> from xmodem import YMODEM
>>> ser = serial.Serial('/dev/ttyUSB0', timeout=0) # or whatever you need
>>> modem = XMODEM(ser)
>>> modem = YMODEM(ser)
:param ser: serial port to read from or write to.
:type getc: class
:param mode: XMODEM protocol mode
:type mode: string
:param pad: Padding character to make the packets match the packet size
:type pad: char
@ -195,11 +142,10 @@ class XMODEM(object):
0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0,
]
def __init__(self, ser, mode='xmodem', pad=b'\x1a'):
def __init__(self, ser, pad=b'\x1a'):
self.ser = ser
self.mode = mode
self.pad = pad
self.log = logging.getLogger('xmodem.XMODEM')
self.log = logging.getLogger('codiUpdate')
def abort(self, count=2, timeout=60):
'''
@ -213,12 +159,11 @@ class XMODEM(object):
for _ in range(count):
self.ser.write(CAN)
def send(self, stream, retry=20, timeout=60, quiet=False, callback=None):
def send(self, filename, retry=20, timeout=60, quiet=False, callback=None):
'''
Send a stream via the XMODEM protocol.
Send a stream via the YMODEM protocol.
>>> stream = open('/etc/issue', 'rb')
>>> print(modem.send(stream))
>>> print(modem.send('filename'))
True
Returns ``True`` upon successful transmission or ``False`` in case of
@ -236,7 +181,7 @@ class XMODEM(object):
:type quiet: bool
:param callback: Reference to a callback function that has the
following signature. This is useful for
getting status updates while a xmodem
getting status updates while a ymodem
transfer is underway.
Expected callback signature:
def callback(total_packets, success_count, error_count)
@ -244,15 +189,7 @@ class XMODEM(object):
'''
# initialize protocol
try:
packet_size = dict(
xmodem = 128,
xmodem1k = 1024,
ymodem = 1024,
)[self.mode]
except KeyError:
raise ValueError("Invalid mode specified: {self.mode!r}"
.format(self=self))
packet_size = 1024
self.log.debug('Begin start sequence, packet_size=%d', packet_size)
error_count = 0
@ -295,30 +232,18 @@ class XMODEM(object):
success_count = 0
total_packets = 0
header_sent = False
if self.mode == 'ymodem':
sequence = 0
filenames = stream
else:
sequence = 1
sequence = 0
stream = None
while True:
# build packet
if not header_sent:
# send packet sequence 0 containing:
# Filename Length [Modification-Date [Mode [Serial-Number]]]
# 'stream' is actually the filename
import os
if len(filenames):
filename = filenames.pop()
stream = open(filename, 'rb')
stat = os.stat(filename)
data = os.path.basename(filename).encode() + NUL + str(stat.st_size).encode()
self.log.debug('ymodem sending : "%s" len:%d', filename, stat.st_size)
else:
# empty file name packet terminates transmission
filename = ''
data = ''.encode()
stream = None
self.log.debug('ymodem done, sending empty header.')
stream = open(filename, 'rb')
stat = os.stat(filename)
data = os.path.basename(filename).encode() + NUL + str(stat.st_size).encode()
self.log.debug('ymodem sending : "%s" len:%d', filename, stat.st_size)
if len(data) <= 128:
header_size = 128
else:
@ -410,9 +335,7 @@ class XMODEM(object):
return False
self.log.info('Transmission successful (ACK received).')
if self.mode == 'ymodem':
# YMODEM - close the stream
stream.close()
stream.close()
return True
def _make_send_header(self, packet_size, sequence):
@ -426,238 +349,13 @@ class XMODEM(object):
return bytearray(_bytes)
def _make_send_checksum(self, crc_mode, data):
assert crc_mode is 1
_bytes = []
if crc_mode:
crc = self.calc_crc(data)
_bytes.extend([crc >> 8, crc & 0xff])
else:
crc = self.calc_checksum(data)
_bytes.append(crc)
return bytearray(_bytes)
def recv(self, stream, crc_mode=1, retry=16, timeout=60, delay=1, quiet=0):
'''
Receive a stream via the XMODEM protocol.
>>> stream = open('/etc/issue', 'wb')
>>> print(modem.recv(stream))
2342
Returns the number of bytes received on success or ``None`` in case of
failure.
:param stream: The stream object to write data to.
:type stream: stream (file, etc.)
:param crc_mode: XMODEM CRC mode
:type crc_mode: int
:param retry: The maximum number of times to try to resend a failed
packet before failing.
:type retry: int
:param timeout: The number of seconds to wait for a response before
timing out.
:type timeout: int
:param delay: The number of seconds to wait between resend attempts
:type delay: int
:param quiet: If ``True``, write transfer information to stderr.
:type quiet: bool
'''
# initiate protocol
error_count = 0
char = 0
cancel = 0
while True:
# first try CRC mode, if this fails,
# fall back to checksum mode
if error_count >= retry:
self.log.info('error_count reached %d, aborting.', retry)
self.abort(timeout=timeout)
return None
elif crc_mode and error_count < (retry // 2):
if not self.ser.write(CRC):
self.log.debug('recv error: putc failed, '
'sleeping for %d', delay)
time.sleep(delay)
error_count += 1
else:
crc_mode = 0
if not self.ser.write(NAK):
self.log.debug('recv error: putc failed, '
'sleeping for %d', delay)
time.sleep(delay)
error_count += 1
char = self.ser.read(1)
if char is None:
self.log.warn('recv error: read timeout in start sequence')
error_count += 1
continue
elif char == SOH:
self.log.debug('recv: SOH')
break
elif char == STX:
self.log.debug('recv: STX')
break
elif char == CAN or char == CAN2:
if cancel:
self.log.info('Transmission canceled: received 2xCAN '
'at start-sequence')
return None
else:
self.log.debug('cancellation at start sequence.')
cancel = 1
else:
error_count += 1
# read data
error_count = 0
income_size = 0
packet_size = 128
sequence = 1
cancel = 0
while True:
while True:
if char == SOH:
if packet_size != 128:
self.log.debug('recv: SOH, using 128b packet_size')
packet_size = 128
break
elif char == STX:
if packet_size != 1024:
self.log.debug('recv: SOH, using 1k packet_size')
packet_size = 1024
break
elif char == EOT:
# We received an EOT, so send an ACK and return the
# received data length.
self.ser.write(ACK)
self.log.info("Transmission complete, %d bytes",
income_size)
return income_size
elif char == CAN or char == CAN2:
# cancel at two consecutive cancels
if cancel:
self.log.info('Transmission canceled: received 2xCAN '
'at block %d', sequence)
return None
else:
self.log.debug('cancellation at block %d', sequence)
cancel = 1
else:
err_msg = ('recv error: expected SOH, EOT; '
'got {0!r}'.format(char))
if not quiet:
print(err_msg, file=sys.stderr)
self.log.warn(err_msg)
error_count += 1
if error_count > retry:
self.log.info('error_count reached %d, aborting.',
retry)
self.abort()
return None
# read sequence
error_count = 0
cancel = 0
self.log.debug('recv: data block %d', sequence)
seq1 = self.ser.read(1)
if seq1 is None:
self.log.warn('read failed to get first sequence byte')
seq2 = None
else:
seq1 = ord(seq1)
seq2 = self.ser.read(1)
if seq2 is None:
self.log.warn('read failed to get second sequence byte')
else:
# second byte is the same as first as 1's complement
seq2 = 0xff - ord(seq2)
if not (seq1 == seq2 == sequence):
# consume data anyway ... even though we will discard it,
# it is not the sequence we expected!
self.log.error('expected sequence %d, '
'got (seq1=%r, seq2=%r), '
'receiving next block, will NAK.',
sequence, seq1, seq2)
self.ser.read(packet_size + 1 + crc_mode)
else:
# sequence is ok, read packet
# packet_size + checksum
data = self.ser.read(packet_size + 1 + crc_mode)
valid, data = self._verify_recv_checksum(crc_mode, data)
# valid data, append chunk
if valid:
income_size += len(data)
stream.write(data)
self.ser.write(ACK)
sequence = (sequence + 1) % 0x100
# get next start-of-header byte
char = self.ser.read(1)
continue
# something went wrong, request retransmission
self.log.warn('recv error: purge, requesting retransmission (NAK)')
while True:
# When the receiver wishes to <nak>, it should call a "PURGE"
# subroutine, to wait for the line to clear. Recall the sender
# tosses any characters in its UART buffer immediately upon
# completing sending a block, to ensure no glitches were mis-
# interpreted. The most common technique is for "PURGE" to
# call the character receive subroutine, specifying a 1-second
# timeout, and looping back to PURGE until a timeout occurs.
# The <nak> is then sent, ensuring the other end will see it.
data = self.ser.read(1)
if data is None:
break
self.ser.write(NAK)
# get next start-of-header byte
char = self.ser.read(1)
continue
def _verify_recv_checksum(self, crc_mode, data):
if crc_mode:
_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)
if not valid:
self.log.warn('recv error: checksum fail '
'(theirs=%04x, ours=%04x), ',
their_sum, our_sum)
else:
_checksum = bytearray([data[-1]])
their_sum = _checksum[0]
data = data[:-1]
our_sum = self.calc_checksum(data)
valid = their_sum == our_sum
if not valid:
self.log.warn('recv error: checksum fail '
'(theirs=%02x, ours=%02x)',
their_sum, our_sum)
return valid, data
def calc_checksum(self, data, checksum=0):
'''
Calculate the checksum for a given block of data, can also be used to
update a checksum.
>>> csum = modem.calc_checksum('hello')
>>> csum = modem.calc_checksum('world', csum)
>>> hex(csum)
'0x3c'
'''
if platform.python_version_tuple() >= ('3', '0', '0'):
return (sum(data) + checksum) % 256
else:
return (sum(map(ord, data)) + checksum) % 256
def calc_crc(self, data, crc=0):
'''
Calculate the Cyclic Redundancy Check for a given block of data, can
@ -675,6 +373,4 @@ class XMODEM(object):
return crc & 0xffff
XMODEM1k = partial(XMODEM, mode='xmodem1k')
YMODEM = partial(XMODEM, mode='ymodem')