pommi/python-itho-wpu
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feat(itho-wpu): add checksum validation for received messages

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This commit is contained in:
Pim van den Berg 2020-11-04 15:13:46 +01:00
parent f989b61789
commit c7b5171a66
1 changed files with 16 additions and 2 deletions
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18
itho-wpu.py
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@ -68,7 +68,8 @@ class I2CSlave():
if b: if b:
logger.debug(f"Received {b} bytes! Status {s}") logger.debug(f"Received {b} bytes! Status {s}")
result = [hex(c) for c in d] result = [hex(c) for c in d]
logger.info(f"Response: {result}") if self.is_checksum_valid(result):
logger.info(f"Response: {result}")
else: else:
logger.error(f"Received number of bytes was {b}") logger.error(f"Received number of bytes was {b}")
@ -81,7 +82,8 @@ class I2CSlave():
if b: if b:
logger.debug(f"Received {b} bytes! Status {s}") logger.debug(f"Received {b} bytes! Status {s}")
result = [hex(c) for c in d] result = [hex(c) for c in d]
q.put(result) if self.is_checksum_valid(result):
q.put(result)
else: else:
logger.error(f"Received number of bytes was {b}") logger.error(f"Received number of bytes was {b}")
else: else:
@ -91,6 +93,18 @@ class I2CSlave():
else: else:
self.close() self.close()
def is_checksum_valid(self, b):
s = 0x80
for i in b[:-1]:
s += int(i, 0)
checksum = 256 - (s % 256)
if checksum == 256:
checksum = 0
if checksum != int(b[-1], 0):
logger.debug(f"Checksum invalid (0x{checksum:02x})")
return False
return True
def close(self): def close(self):
self.pi.bsc_i2c(0) self.pi.bsc_i2c(0)
self.pi.stop() self.pi.stop()