# -*- coding: utf-8 -*-
"""
Copyright (c) 2018 beyond-blockchain.org.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
"""
import os
import sys
import hashlib
import msgpack
import traceback
current_dir = os.path.abspath(os.path.dirname(__file__))
sys.path.append(os.path.join(current_dir, "../.."))
from bbclib.libs import bbclib_utils
import bbclib
from bbclib import id_length_conf
[docs]class BBcAsset:
"""Asset part in a transaction"""
def __init__(self, user_id=None, asset_file=None, asset_body=None, id_length=None, version=2):
if id_length is not None:
bbclib.configure_id_length_all(id_length)
self.version = version
self.asset_id = None
if user_id is not None:
self.user_id = user_id[:id_length_conf["user_id"]]
else:
self.user_id = None
self.nonce = bbclib_utils.get_random_value(id_length_conf["nonce"])
self.asset_file_size = 0
self.asset_file = None
self.asset_file_digest = None
self.asset_body_size = 0
self.asset_body = None
if user_id is not None:
self.add(user_id, asset_file, asset_body)
def __str__(self):
ret = " Asset:\n"
ret += " asset_id: %s\n" % bbclib_utils.str_binary(self.asset_id)
ret += " user_id: %s\n" % bbclib_utils.str_binary(self.user_id)
ret += " nonce: %s\n" % bbclib_utils.str_binary(self.nonce)
ret += " file_size: %d\n" % self.asset_file_size
ret += " file_digest: %s\n" % bbclib_utils.str_binary(self.asset_file_digest)
ret += " body_size: %d\n" % self.asset_body_size
ret += " body: %s\n" % self.asset_body
return ret
[docs] def add(self, user_id=None, asset_file=None, asset_body=None):
"""Add parts in this object"""
self.user_id = user_id[:id_length_conf["user_id"]]
if asset_file is not None:
self.asset_file = asset_file
self.asset_file_size = len(asset_file)
self.asset_file_digest = hashlib.sha256(bytes(asset_file)).digest()
if asset_body is not None:
self.asset_body = asset_body
if isinstance(asset_body, str):
self.asset_body = asset_body.encode()
self.asset_body_size = len(asset_body)
self.digest()
[docs] def digest(self):
"""Calculate the digest
The digest corresponds to the asset_id of this object
Returns:
bytes: asset_id (or digest)
"""
target = self.pack(for_digest_calculation=True)
self.asset_id = hashlib.sha256(target).digest()[:id_length_conf["asset_id"]]
return self.asset_id
[docs] def get_asset_file(self):
"""Get asset file content and its digest
Returns:
bytes: digest of the file content
bytes: the file content
"""
if self.asset_file is None:
return None, None
return self.asset_file_digest, self.asset_file
[docs] def recover_asset_file(self, asset_file):
"""Recover asset file info from the given raw content"""
digest = hashlib.sha256(asset_file).digest()
if digest == self.asset_file_digest:
self.asset_file = asset_file
return True
else:
return False
[docs] def pack(self, for_digest_calculation=False):
"""Pack this object
Args:
for_digest_calculation (bool): True if digest calculation
Returns:
bytes: packed binary data
"""
dat = bytearray()
if not for_digest_calculation:
dat.extend(bbclib_utils.to_bigint(self.asset_id, size=id_length_conf["asset_id"]))
dat.extend(bbclib_utils.to_bigint(self.user_id, size=id_length_conf["user_id"]))
dat.extend(bbclib_utils.to_2byte(len(self.nonce)))
dat.extend(self.nonce)
dat.extend(bbclib_utils.to_4byte(self.asset_file_size))
if self.asset_file_size > 0:
dat.extend(bbclib_utils.to_bigint(self.asset_file_digest))
if isinstance(self.asset_body, dict):
dat.extend(bbclib_utils.to_2byte(1))
astbdy = msgpack.dumps(self.asset_body)
dat.extend(bbclib_utils.to_2byte(len(astbdy)))
dat.extend(astbdy)
else:
dat.extend(bbclib_utils.to_2byte(0))
dat.extend(bbclib_utils.to_2byte(self.asset_body_size))
if self.asset_body_size > 0:
dat.extend(self.asset_body)
return bytes(dat)
[docs] def unpack(self, data):
"""Unpack into this object
Args:
data (bytes): packed binary data
Returns:
bool: True if successful
"""
ptr = 0
try:
ptr, self.asset_id = bbclib_utils.get_bigint(ptr, data)
id_length_conf["asset_id"] = len(self.asset_id)
ptr, self.user_id = bbclib_utils.get_bigint(ptr, data)
id_length_conf["user_id"] = len(self.user_id)
ptr, noncelen = bbclib_utils.get_n_byte_int(ptr, 2, data)
id_length_conf["nonce"] = noncelen
ptr, self.nonce = bbclib_utils.get_n_bytes(ptr, noncelen, data)
ptr, self.asset_file_size = bbclib_utils.get_n_byte_int(ptr, 4, data)
if self.asset_file_size > 0:
ptr, self.asset_file_digest = bbclib_utils.get_bigint(ptr, data)
else:
self.asset_file_digest = None
ptr, dict_flag = bbclib_utils.get_n_byte_int(ptr, 2, data)
if dict_flag != 1:
ptr, self.asset_body_size = bbclib_utils.get_n_byte_int(ptr, 2, data)
if self.asset_body_size > 0:
ptr, self.asset_body = bbclib_utils.get_n_bytes(ptr, self.asset_body_size, data)
else:
ptr, sz = bbclib_utils.get_n_byte_int(ptr, 2, data)
ptr, astbdy = bbclib_utils.get_n_bytes(ptr, sz, data)
self.asset_body = msgpack.loads(astbdy)
self.asset_body_size = len(self.asset_body)
except:
traceback.print_exc()
return False
return True