151 lines
5 KiB
Python
151 lines
5 KiB
Python
#!/usr/bin/python3.9
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"""
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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):
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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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# object attributes view normalization
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ugly_attrs = data["header"]["attributes"]
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data["header"]["attributes"] = {}
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for attr in ugly_attrs:
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data["header"]["attributes"][attr["key"]] = attr["value"]
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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):
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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):
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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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# reencoding Child Object IDs
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# { 'value': <Base58 encoded OID> } -> <Base64 encoded OID>
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for ind, val in enumerate(data["header"]["split"]["children"]):
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data["header"]["split"]["children"][ind] = json_reencode(val["value"])
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data["header"]["split"]["splitID"] = json_reencode(data["header"]["split"]["splitID"])
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data["header"]["split"]["previous"] = (
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json_reencode(data["header"]["split"]["previous"]["value"])
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if data["header"]["split"]["previous"]
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else None
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)
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data["header"]["split"]["parent"] = (
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json_reencode(data["header"]["split"]["parent"]["value"])
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if data["header"]["split"]["parent"]
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else None
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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_storage_group(data: 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):
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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):
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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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data["body"]["object"]["target"]["container"] = json_reencode(
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data["body"]["object"]["target"]["container"]["value"]
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)
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data["body"]["object"]["target"]["objects"] = [json_reencode(obj["value"]) for obj in data["body"]["object"]["target"]["objects"]]
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return data
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def json_reencode(data: 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
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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):
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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):
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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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