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fix: the format for comparison between RTCM packet preamble and current byte(#14) #15

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fix: the format for comparison between RTCM packet preamble and current byte(#14) #15

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13 changes: 8 additions & 5 deletions src/ntrip_client/rtcm_parser.py
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Original file line number Diff line number Diff line change
Expand Up @@ -64,19 +64,22 @@ def parse(self, buffer):
rtcm_packets = []
while index < len(combined_buffer):
# Find the start of the RTCM 3.2 packet
if combined_buffer[index] == _RTCM_3_2_PREAMBLE:
ascii_values = []
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For me the buffer still comes in as a byte array by default, and this causes the node to crash for me. so we should have some logic in here to handle both cases. Also I think that you could use the encode function instead of looping. I had success with the following implementation, but as I said, my buffer is already bytes, so please let me know if this works for you

if isinstance(combined_buffer, str):
  ascii_values = combined_buffer.encode('utf-8')
elif isinstance(combined_buffer, bytes):
  ascii_values = combined_buffer
else:
  raise Exception('Buffer type is "{}" not a string or bytes, so we cannot parse it.'.format(type(combined_buffer)))

Also I think a better name for ascii_values would be combined_buffer_bytes

for ch in combined_buffer:
ascii_values.append(ord(ch))
if ascii_values[index] == _RTCM_3_2_PREAMBLE:
# Make sure we have enough data to find the length
if len(combined_buffer) <= index + 2:
if len(ascii_values) <= index + 2:
self._logdebug('Found beginning of RTCM packet at {}, but there is not enough data in the buffer to find the message length'.format(index))
self._caching_data = True
buffer = buffer[index:]
break

# Make sure we have enough data in the packet to validate it
message_length = (combined_buffer[index + 1] << 8 | combined_buffer[index + 2]) & 0x03FF
if index + message_length + 6 <= len(combined_buffer):
message_length = (ascii_values[index + 1] << 8 | ascii_values[index + 2]) & 0x03FF
if index + message_length + 6 <= len(ascii_values):
# Grab the packet from the buffer, and verify that it is valid by comparing checksums
packet = combined_buffer[index:index + message_length + 6]
packet = ascii_values[index:index + message_length + 6]
expected_checksum = packet[-3] << 16 | packet[-2] << 8 | packet[-1]
actual_checksum = self._checksum(packet[:-3])
if expected_checksum == actual_checksum:
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