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bohd4nx
36 lines
1.1 KiB
Python
36 lines
1.1 KiB
Python
import base64
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from pytoniq_core import Cell
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from fragmentapi.types import ParseError
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def clean_decode(payload: str) -> str:
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"""Decode a base64-encoded BOC payload to a plain-text comment string.
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Fragment transaction payloads are BOC-serialised TVM cells. This function
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base64-decodes the payload, parses the cell, skips the 32-bit op-code
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prefix, and reads the snake-encoded UTF-8 comment.
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Args:
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payload: Base64url-encoded BOC string (padding is added automatically).
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Returns:
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Decoded comment string, or ``""`` for an empty payload.
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Raises:
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ParseError: If the payload cannot be decoded or parsed.
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"""
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s = payload.strip()
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if not s:
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return ""
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s += "=" * (-len(s) % 4)
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try:
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boc = base64.b64decode(s)
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cell = Cell.one_from_boc(boc)
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sl = cell.begin_parse()
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sl.load_uint(32) # op code — always 0 for text comment
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return sl.load_snake_string().strip()
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except Exception as exc:
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raise ParseError(ParseError.UNPARSEABLE.format(context="payload decode", exc=exc)) from exc
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