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https://git.ugnet.gay/CrossTalk/azul.git
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init
This commit is contained in:
Athena Funderburg
@@ -0,0 +1,249 @@
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import struct
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from array import array
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from dataclasses import dataclass
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from .tlv import TLV, marshal_tlvs, unmarshal_tlvs
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@dataclass
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class Buffer:
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data: bytes
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def __init__(self, data: bytes = b''):
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self.data = data
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def __len__(self) -> int:
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return len(self.data)
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########################
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# read_xxx() functions #
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########################
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def read_bytes(self, length: int) -> bytes:
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"""Reads the specified amount of bytes from the buffer.
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Args:
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length: bytes to read
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Returns:
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bytes: the bytes read
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"""
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value = self.data[:length]
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self.data = self.data[length:]
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return value
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def read_u8(self) -> int:
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"""Reads a byte (8 bits) from the buffer.
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Returns:
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int: The read byte from the buffer.
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"""
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value, = struct.unpack('>B', self.data[:1])
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self.data = self.data[1:]
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return value
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def read_u16(self) -> int:
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"""Reads an unsigned short (16 bits) from the buffer.
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Returns:
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int: The read unsigned short from the buffer.
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"""
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value, = struct.unpack('>H', self.data[:2])
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self.data = self.data[2:]
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return value
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def read_u32(self) -> int:
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"""Reads an unsigned int (32 bits) from the buffer.
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Returns:
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int: The read unsigned int from the buffer.
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"""
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value, = struct.unpack('>L', self.data[:4])
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self.data = self.data[4:]
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return value
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def read_string(self, length: int) -> str:
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"""Reads a string with the specified length from the buffer.
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Args:
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length: The length of the string to read.
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Returns:
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str: The read string from the buffer."""
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str_bytes = self.data[:length]
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self.data = self.data[length:]
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return str_bytes.decode('utf-8')
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def read_string_u8(self) -> str:
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"""Reads a string prepended with a u8 showing the length of the string.
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Returns:
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str: The read string from the buffer.
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"""
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return self.read_string(self.read_u8())
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def read_string_u16(self) -> str:
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"""Reads a string prepended with a u16 showing the length of the string.
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Returns:
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str: The read string from the buffer.
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"""
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return self.read_string(self.read_u16())
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def read_string_u32(self) -> str:
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"""Reads a string prepended with a u32 showing the length of the string.
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Returns:
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str: The read string from the buffer.
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"""
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return self.read_string(self.read_u32())
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def read_tlv_block(self) -> array[TLV]:
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"""Reads a TLV list prepended with a u16 showing the number of TLVs in the list, from the buffer.
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Returns:
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array[TLV]: The TLVs found in the block.
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"""
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length = self.read_u16()
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tlvs = []
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for _ in range(length):
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type, length = struct.unpack('>HH', self.data[0:4])
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value = self.data[4:length + 4]
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# make sure length is not too long
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assert len(self) > length - 4
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tlvs.append(TLV(type, value))
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self.data = self.data[length + 4:]
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return tlvs
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def read_tlv_l_block(self) -> array[TLV]:
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"""Reads a list of TLVs prepended with a u16 showing the length of the total TLV bytes, from the buffer.
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Returns:
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array[TLV]: The TLVs found in the block.
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"""
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length = self.read_u16()
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tlvs = unmarshal_tlvs(self.data[:length])
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self.data = self.data[length:]
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return tlvs
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#########################
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# write_xxx() functions #
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#########################
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def write_bytes(self, value: bytes) -> None:
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"""Writes the specified bytes into the buffer.
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Args:
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value: The bytes to write into the buffer.
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"""
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self.data += value
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def write_u8(self, value: int) -> None:
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"""Writes a byte (8 bits) into the buffer.
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Args:
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value: The byte to write into the buffer.
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"""
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self.data += struct.pack('>B', value)
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def write_u16(self, value: int) -> None:
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"""Writes a unsigned short (16 bits) into the buffer.
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Args:
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value: The unsigned short to write into the buffer.
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"""
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self.data += struct.pack('>H', value)
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def write_u32(self, value: int) -> None:
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"""Writes a unsigned int (32 bits) into the buffer.
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Args:
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value: The unsigned int to write into the buffer.
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"""
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self.data += struct.pack('>L', value)
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def write_string(self, value: str) -> None:
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"""Writes a string imto the buffer.
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Args:
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value: The string to write into the buffer.
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"""
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self.data += value.encode('utf-8')
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def write_string_u8(self, value: str) -> None:
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"""Writes a string prepended with a u8 showing the length of the string into the buffer.
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Args:
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value: The string to write into the buffer.
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"""
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self.write_u8(len(value))
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self.write_string(value)
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def write_string_u16(self, value: str) -> None:
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"""Writes a string prepended with a u16 showing the length of the string into the buffer.
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Args:
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value: The string to write into the buffer.
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"""
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self.write_u16(len(value))
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self.write_string(value)
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def write_string_u32(self, value: str) -> None:
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"""Writes a string prepended with a u32 showing the length of the string into the buffer.
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Args:
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value: The string to write into the buffer.
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"""
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self.write_u32(len(value))
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self.write_string(value)
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def write_tlv(self, tlv: TLV) -> None:
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"""Writes the specified TLV into the buffer.
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Args:
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tlv: The TLV to write into the buffer.
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"""
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self.data += tlv.marshal()
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def write_tlvs(self, tlvs: array[TLV]) -> None:
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"""Writes a list of TLVs into the buffer.
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Args:
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tlvs: The list of TLVs to write into the buffer.
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"""
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self.data += marshal_tlvs(tlvs)
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def write_tlv_block(self, tlvs: array[TLV]) -> None:
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"""Writes a list of TLVs prepended with a u16 describing the TLV count in the list, into the buffer.
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Args:
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tlvs: The list of TLVs to write into the buffer.
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"""
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self.write_u16(len(tlvs))
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self.write_tlvs(tlvs)
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def write_tlv_l_block(self, tlvs: array[TLV]) -> None:
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"""Writes a list of TLVs prepended with a u16 describing the length of the total TLV bytes, into the buffer.
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Args:
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tlvs: The list of TLVs to write into the buffers.
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"""
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marshalled_tlvs = marshal_tlvs(tlvs)
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self.write_u16(len(marshalled_tlvs))
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self.write_bytes(marshalled_tlvs)
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