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| 1 | +""" |
| 2 | + Copyright (c) 2024, The OpenThread Authors. |
| 3 | + All rights reserved. |
| 4 | +
|
| 5 | + Redistribution and use in source and binary forms, with or without |
| 6 | + modification, are permitted provided that the following conditions are met: |
| 7 | + 1. Redistributions of source code must retain the above copyright |
| 8 | + notice, this list of conditions and the following disclaimer. |
| 9 | + 2. Redistributions in binary form must reproduce the above copyright |
| 10 | + notice, this list of conditions and the following disclaimer in the |
| 11 | + documentation and/or other materials provided with the distribution. |
| 12 | + 3. Neither the name of the copyright holder nor the |
| 13 | + names of its contributors may be used to endorse or promote products |
| 14 | + derived from this software without specific prior written permission. |
| 15 | +
|
| 16 | + THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| 17 | + AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 18 | + IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 19 | + ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
| 20 | + LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 21 | + CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 22 | + SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 23 | + INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 24 | + CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 25 | + ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 26 | + POSSIBILITY OF SUCH DAMAGE. |
| 27 | +""" |
| 28 | + |
| 29 | +from __future__ import annotations |
| 30 | +from typing import List |
| 31 | + |
| 32 | + |
| 33 | +class TLV(): |
| 34 | + def __init__(self, type: int = None, value: bytes = None): |
| 35 | + self.type: int = type |
| 36 | + self.value: bytes = value |
| 37 | + |
| 38 | + def __str__(self): |
| 39 | + return f'TLV\n\tTYPE:\t0x{self.type:02x}\n\tVALUE:\t{self.value}' |
| 40 | + |
| 41 | + @staticmethod |
| 42 | + def parse_tlvs(data: bytes) -> List[TLV]: |
| 43 | + res: List[TLV] = [] |
| 44 | + while data: |
| 45 | + next_tlv = TLV.from_bytes(data) |
| 46 | + next_tlv_size = len(next_tlv.to_bytes()) |
| 47 | + data = data[next_tlv_size:] |
| 48 | + res.append(next_tlv) |
| 49 | + return res |
| 50 | + |
| 51 | + @staticmethod |
| 52 | + def from_bytes(data: bytes) -> TLV: |
| 53 | + res = TLV() |
| 54 | + res.set_from_bytes(data) |
| 55 | + return res |
| 56 | + |
| 57 | + def set_from_bytes(self, data: bytes): |
| 58 | + self.type = data[0] |
| 59 | + header_len = 2 |
| 60 | + if data[1] == 0xFF: |
| 61 | + header_len = 4 |
| 62 | + length = int.from_bytes(data[1:header_len], byteorder='big') |
| 63 | + self.value = data[header_len:header_len + length] |
| 64 | + |
| 65 | + def to_bytes(self) -> bytes: |
| 66 | + has_long_header = len(self.value) >= 255 |
| 67 | + header_len = 4 if has_long_header else 2 |
| 68 | + len_bytes = len(self.value).to_bytes(header_len - 1, byteorder='big') |
| 69 | + header = bytes([self.type]) + len_bytes |
| 70 | + return header + self.value |
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