"""
Copyright 2019 de la Dirección General de Sistemas Informáticos – Secretaría Legal y Técnica - Nación.
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/
"""
import base64
from django.core.exceptions import ValidationError
from django.utils.translation import gettext as _
from rest_framework import status
from rest_framework.views import APIView
from rest_framework.response import Response
from web3.exceptions import CannotHandleRequest
from raven.contrib.django.raven_compat.models import client
from rest_framework.schemas import ManualSchema
import coreschema,coreapi
from app.managers import TimestampManager
from app.utils import Utils
from TsaApi.local_settings import TEMPORARY_OTS_PREFIX, PERMANENT_OTS_PREFIX, CONTRACTS
class Stamp(APIView):
"""
[POST]
Permite realizar un stamp de un archivo
Parámetros recibidos:
[Content-Type:application/json]
- file_hash: El hash del archivo encodeado en sha256
Devuelve un OTS para poder verificar en el futuro que el archivo fue incluido a la Blockchain
Ejemplo:
{
"file_hash": "1957db7fe23e4be1740ddeb941ddda7ae0a6b782e536a9e00b5aa82db1e84547"
}
"""
schema = ManualSchema(fields=[
coreapi.Field(
name='file_hash',
required=True,
location='form',
schema=coreschema.String(),
description='El hash del archivo encodeado en sha256',
),
])
def post(self, request):
try:
if not request.data.get('file_hash'):
raise ValidationError('file_hash')
file_hash = request.data.get('file_hash')
ots_hash = Utils.get_ots_hash(file_hash)
tx_hash = TimestampManager.stamp(ots_hash, file_hash)
#Al OTS se le agrega la transacción para poder verificar luego si está pendiente de subida
ots = Utils.get_temporary_ots(ots_hash, tx_hash.hex())
return Response({_('status'): _('success'), _('temporary_rd'): base64.b64encode(ots.encode('utf-8')).decode('utf-8')}, status=status.HTTP_200_OK)
except ValidationError as e:
return Response({_('status'): _('failure'), _('messages'): _('parameter_missing') % e.message}, status=status.HTTP_400_BAD_REQUEST)
except CannotHandleRequest:
return Response({_('status'): _('failure'), _('messages'): _('could_not_connect')}, status=status.HTTP_503_SERVICE_UNAVAILABLE)
except Exception as e:
client.captureException()
return Response({_('status'): _('failure'), _('messages'): _('operation_failed')}, status=status.HTTP_500_INTERNAL_SERVER_ERROR)
class Verify(APIView):
"""
[POST]
Permite verificar que un archivo fue subido a la Blockchain
Parámetros recibidos:
[Content-Type:application/json]
- file_hash: El hash del archivo original encodeado en sha256
- rd: Recibo digital recibido como prueba al momento de realizar el stamp
Devuelve número de bloque, fecha y hora de subida a la Blockchain
Ejemplo:
{
"file_hash": "1957db7fe23e4be1740ddeb941ddda7ae0a6b782e536a9e00b5aa82db1e84547",
"rd": "NzNkYzA5OGJkODlmZjdlMjc4OGFjMzJlNmU2ODdiOTdmODdiMTBjMWIyNzg5OTFlMDNkN2E2YWVkMDk3ODJkZTAxLTB4NGM2ZmNiNDBhMmUyZGVjYzc2YWQzMjM3MDU2NzZjMjljYWE1MmIyYjZkMDdiMDIzYjBhY2EzOWYzZGIxYmRlZg=="
}
"""
schema = ManualSchema(fields=[
coreapi.Field(
name='file_hash',
required=True,
location='form',
schema=coreschema.String(),
description='El hash del archivo encodeado en sha256',
), coreapi.Field(
name='rd',
required=True,
location='form',
schema=coreschema.String(),
description='El recibo digital recibido al hacer el stamp del archivo encodeado en sha256',
)
])
def post(self, request):
try:
if not request.data.get('file_hash'):
raise ValidationError('file_hash')
if not request.data.get('rd'):
raise ValidationError('rd')
original_file_hash = request.data.get('file_hash')
base64_ots = request.data.get('rd')
ots = base64.b64decode(base64_ots).decode('utf-8')
if ots[:2] == PERMANENT_OTS_PREFIX:
ots_version, file_hash, ots_hash, tx_hash, block_number = ots.split('-')
method_name, args = Utils.decode_contract_call(CONTRACTS['01']['abi'], TimestampManager.get_transaction(tx_hash).input)
if args[0].decode('utf-8') == ots_hash and args[1].decode('utf-8') == file_hash:
block = TimestampManager.get_block(int(block_number))
return Response({_('status'): _('success'),
_('permanent_rd'): base64.b64encode(Utils.get_permanent_ots(original_file_hash, ots_hash, tx_hash, block.number).encode('utf-8')).decode('utf-8'),
_('messages'): _('file_uploaded') % (
file_hash, str(block.number), str(Utils.datetime_from_timestamp(block.timestamp)))},
status=status.HTTP_200_OK)
else:
return Response({_('status'): _('failure'), _('messages'): _('file_not_found')},
status=status.HTTP_404_NOT_FOUND)
else:
ots_version, ots_hash, tx_hash = ots.split('-')
transaction = TimestampManager.get_transaction(tx_hash)
contract_version = ots_hash[-2:]
if TimestampManager.verify(contract_version, ots_hash, original_file_hash):
if (TimestampManager.get_last_block_number() - transaction.blockNumber) < Utils.required_block_difference(TimestampManager.get_signers_count()):
return Response({_('status'): _('pending'), _('messages'): _('transaction_pending')},
status=status.HTTP_200_OK)
else:
block = TimestampManager.get_block(TimestampManager.get_block_number(contract_version, ots_hash))
return Response({_('status'): _('success'),
_('permanent_rd'): base64.b64encode(Utils.get_permanent_ots(original_file_hash, ots_hash, tx_hash, block.number).encode('utf-8')).decode('utf-8'),
_('messages'): _('file_uploaded') % (original_file_hash, str(block.number), str(
Utils.datetime_from_timestamp(block.timestamp)))}, status=status.HTTP_200_OK)
else:
try:
if transaction and not transaction.blockNumber:
return Response({_('status'): _('pending'), _('messages'): _('transaction_pending')}, status=status.HTTP_200_OK)
except ValueError:
pass
return Response({_('status'): _('failure'), _('messages'): _('file_not_found')},status=status.HTTP_404_NOT_FOUND)
except ValidationError as e:
return Response({_('status'): _('failure'), _('messages'): _('parameter_missing') % e.message}, status=status.HTTP_400_BAD_REQUEST)
except CannotHandleRequest:
return Response({_('status'): _('failure'), _('messages'): _('could_not_connect')}, status=status.HTTP_503_SERVICE_UNAVAILABLE)
except Exception as e:
client.captureException()
return Response({_('status'): _('failure'), _('messages'): _('operation_failed')}, status=status.HTTP_500_INTERNAL_SERVER_ERROR)