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from typing import List | |
import struct | |
class IncomingMessage: | |
""" | |
Utility class for reading the message written to a SideChannel. | |
Values must be read in the order they were written. | |
""" | |
def __init__(self, buffer: bytes, offset: int = 0): | |
""" | |
Create a new IncomingMessage from the bytes. | |
""" | |
self.buffer = buffer | |
self.offset = offset | |
def read_bool(self, default_value: bool = False) -> bool: | |
""" | |
Read a boolean value from the message buffer. | |
:param default_value: Default value to use if the end of the message is reached. | |
:return: The value read from the message, or the default value if the end was reached. | |
""" | |
if self._at_end_of_buffer(): | |
return default_value | |
val = struct.unpack_from("<?", self.buffer, self.offset)[0] | |
self.offset += 1 | |
return val | |
def read_int32(self, default_value: int = 0) -> int: | |
""" | |
Read an integer value from the message buffer. | |
:param default_value: Default value to use if the end of the message is reached. | |
:return: The value read from the message, or the default value if the end was reached. | |
""" | |
if self._at_end_of_buffer(): | |
return default_value | |
val = struct.unpack_from("<i", self.buffer, self.offset)[0] | |
self.offset += 4 | |
return val | |
def read_float32(self, default_value: float = 0.0) -> float: | |
""" | |
Read a float value from the message buffer. | |
:param default_value: Default value to use if the end of the message is reached. | |
:return: The value read from the message, or the default value if the end was reached. | |
""" | |
if self._at_end_of_buffer(): | |
return default_value | |
val = struct.unpack_from("<f", self.buffer, self.offset)[0] | |
self.offset += 4 | |
return val | |
def read_float32_list(self, default_value: List[float] = None) -> List[float]: | |
""" | |
Read a list of float values from the message buffer. | |
:param default_value: Default value to use if the end of the message is reached. | |
:return: The value read from the message, or the default value if the end was reached. | |
""" | |
if self._at_end_of_buffer(): | |
return [] if default_value is None else default_value | |
list_len = self.read_int32() | |
output = [] | |
for _ in range(list_len): | |
output.append(self.read_float32()) | |
return output | |
def read_string(self, default_value: str = "") -> str: | |
""" | |
Read a string value from the message buffer. | |
:param default_value: Default value to use if the end of the message is reached. | |
:return: The value read from the message, or the default value if the end was reached. | |
""" | |
if self._at_end_of_buffer(): | |
return default_value | |
encoded_str_len = self.read_int32() | |
val = self.buffer[self.offset : self.offset + encoded_str_len].decode("ascii") | |
self.offset += encoded_str_len | |
return val | |
def get_raw_bytes(self) -> bytes: | |
""" | |
Get a copy of the internal bytes used by the message. | |
""" | |
return bytearray(self.buffer) | |
def _at_end_of_buffer(self) -> bool: | |
return self.offset >= len(self.buffer) | |