136 lines
4.6 KiB
Python
136 lines
4.6 KiB
Python
"""
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When doing requests to NeoFS, we get JSON output as an automatically decoded
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structure from protobuf. Some fields are decoded with boilerplates and binary
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values are Base64-encoded.
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This module contains functions which rearrange the structure and reencode binary
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data from Base64 to Base58.
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"""
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import base64
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import base58
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def decode_simple_header(data: dict) -> dict:
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"""
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This function reencodes Simple Object header and its attributes.
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"""
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try:
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data = decode_common_fields(data)
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# Normalize object attributes
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data["header"]["attributes"] = {
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attr["key"]: attr["value"] for attr in data["header"]["attributes"]
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}
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except Exception as exc:
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raise ValueError(f"failed to decode JSON output: {exc}") from exc
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return data
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def decode_split_header(data: dict) -> dict:
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"""
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This function rearranges Complex Object header.
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The header holds SplitID, a random unique
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number, which is common among all splitted objects, and IDs of the Linking
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Object and the last splitted Object.
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"""
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try:
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data["splitId"] = json_reencode(data["splitId"])
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data["lastPart"] = json_reencode(data["lastPart"]["value"]) if data["lastPart"] else None
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data["link"] = json_reencode(data["link"]["value"]) if data["link"] else None
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except Exception as exc:
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raise ValueError(f"failed to decode JSON output: {exc}") from exc
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return data
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def decode_linking_object(data: dict) -> dict:
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"""
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This function reencodes Linking Object header.
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It contains IDs of child Objects and Split Chain data.
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"""
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try:
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data = decode_simple_header(data)
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split = data["header"]["split"]
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split["children"] = [json_reencode(item["value"]) for item in split["children"]]
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split["splitID"] = json_reencode(split["splitID"])
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split["previous"] = json_reencode(split["previous"]["value"]) if split["previous"] else None
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split["parent"] = json_reencode(split["parent"]["value"]) if split["parent"] else None
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except Exception as exc:
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raise ValueError(f"failed to decode JSON output: {exc}") from exc
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return data
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def decode_storage_group(data: dict) -> dict:
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"""
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This function reencodes Storage Group header.
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"""
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try:
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data = decode_common_fields(data)
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except Exception as exc:
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raise ValueError(f"failed to decode JSON output: {exc}") from exc
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return data
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def decode_tombstone(data: dict) -> dict:
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"""
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This function reencodes Tombstone header.
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"""
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try:
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data = decode_simple_header(data)
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data["header"]["sessionToken"] = decode_session_token(data["header"]["sessionToken"])
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except Exception as exc:
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raise ValueError(f"failed to decode JSON output: {exc}") from exc
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return data
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def decode_session_token(data: dict) -> dict:
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"""
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This function reencodes a fragment of header which contains
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information about session token.
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"""
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target = data["body"]["object"]["target"]
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target["container"] = json_reencode(target["container"]["value"])
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target["objects"] = [json_reencode(obj["value"]) for obj in target["objects"]]
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return data
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def json_reencode(data: str) -> str:
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"""
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According to JSON protocol, binary data (Object/Container/Storage Group IDs, etc)
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is converted to string via Base58 encoder. But we usually operate with Base64-encoded format.
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This function reencodes given Base58 string into the Base64 one.
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"""
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return base58.b58encode(base64.b64decode(data)).decode("utf-8")
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def encode_for_json(data: str) -> str:
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"""
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This function encodes binary data for sending them as protobuf
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structures.
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"""
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return base64.b64encode(base58.b58decode(data)).decode("utf-8")
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def decode_common_fields(data: dict) -> dict:
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"""
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Despite of type (simple/complex Object, Storage Group, etc) every Object
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header contains several common fields.
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This function rearranges these fields.
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"""
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data["objectID"] = json_reencode(data["objectID"]["value"])
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header = data["header"]
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header["containerID"] = json_reencode(header["containerID"]["value"])
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header["ownerID"] = json_reencode(header["ownerID"]["value"])
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header["payloadHash"] = json_reencode(header["payloadHash"]["sum"])
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header["version"] = f"{header['version']['major']}{header['version']['minor']}"
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# Homomorphic hash is optional and its calculation might be disabled in trusted network
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if header.get("homomorphicHash"):
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header["homomorphicHash"] = json_reencode(header["homomorphicHash"]["sum"])
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return data
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