def send_message(self, message, tries=0, no_wait=False):
"""
sends input with write
returns output with read.
if skip_read is True, it only returns true, you have to read
yourself.
"""
if message:
self.write(message.as_bin())
# time.sleep(0.1)
acknowledge = self.connection.read(1)
self.slog(acknowledge, True)
# if nak, we retry, if ack, we read, if other, we raise.
if acknowledge == ensure_bytes(chr(ACK)):
# everything alright.
if not no_wait:
return self.receive()
return True
elif acknowledge == ensure_bytes(chr(NAK)):
# not everything allright.
#if tries < 3:
# return self.send_message(message, tries + 1, no_answer)
#else:
raise common.TransportLayerException("Could not send message")
elif not acknowledge:
# this happens quite a lot with the ingenico devices.
# possibly a workaround would be nice.
raise common.TransportTimeoutException(
"No Answer, Possible Timeout")
else:
raise common.TransportLayerException(
"Unknown Acknowledgment Byte %s" % conv.bs2hl(acknowledge))
def read(self, timeout=TIMEOUT_T2):
"""
reads a message packet. any errors are raised directly.
"""
# if in 5 seconds no message appears, we respond with a nak and raise an error.
self.connection.timeout = timeout
apdu = []
crc = None
header = self.connection.read(2)
header = conv.bs2hl(header)
# test if there was a transmission:
if header == []:
raise common.TransportLayerException('Reading Header Timeout')
# test our header to be valid
if header != [DLE, STX]:
self.slog(header, True)
raise common.TransportLayerException("Header Error: %s" % header)
# read until DLE, ETX is reached.
dle = False
# timeout to T1 after header.
self.connection.timeout = TIMEOUT_T1
while not crc:
b = ord(self.connection.read(1)) # read a byte.
if b is None:
# timeout
raise common.TransportLayerException(
"Timeout T1 reading stream.")
if b == ETX and dle:
# dle was set, and this is ETX, so we are at the end.
# we read the CRC now.
crc = self.connection.read(2)
if not crc:
raise common.TransportLayerException(
"Timeout T1 reading CRC")
else:
crc = conv.bs2hl(crc)
# and break
continue
elif b == DLE:
if not dle:
# this is a dle
dle = True
continue
else:
# this is the second dle. we take it.
dle = False
elif dle:
# dle was set, but we got no etx here.
# this seems to be an error.
raise common.TransportLayerException(
"DLE without sense detected.")
# we add this byte to our apdu.
apdu += [b]
self.slog(header + apdu + [DLE, ETX] + crc, True)
return crc, apdu
def dismantle_serial_packet(data):
apdu = []
crc = None
i = 2
header = data[:i]
#header = conv.bs2hl(header)
# test if there was a transmission:
if header == []:
raise common.TransportLayerException('No Header')
# test our header to be valid
if header != [DLE, STX]:
raise common.TransportLayerException("Header Error: %s" % header)
# read until DLE, ETX is reached.
dle = False
while not crc and i < len(data):
b = data[i] # read a byte.
if b == ETX and dle:
# dle was set, and this is ETX, so we are at the end.
# we read the CRC now.
crc = [data[i + 1], data[i + 2]]
# and break
continue
elif b == DLE:
if not dle:
# this is a dle
dle = True
continue
else:
# this is the second dle. we take it.
dle = False
elif dle:
# dle was set, but we got no etx here.
# this seems to be an error.
raise Exception("DLE without sense detected.")
# we add this byte to our apdu.
apdu += [b]
i += 1
return crc, apdu