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#!/usr/bin/env python3
import re
import os
import hashlib
import hmac
from flask import Flask, abort, request, Response
import filecrypt
app = Flask(__name__)
# default values
app.config['MAX_UPLOAD_SIZE'] = int(100e6)
app.config['MAX_UPLOAD_CHUNK_SIZE'] = int(100e6)
app.config.from_envvar('SECURE_DOWNLOAD_SETTINGS')
upload_keys = {}
for v in app.config.get('UPLOAD_KEYS', []):
upload_keys[filecrypt.key_id(v)] = v
BASE64_RE = re.compile('^[A-Za-z0-9+-_]+=*$')
@app.route('/<file_id>/<token>/<filename>', methods=['GET'])
def download(file_id, token, filename):
if not BASE64_RE.match(file_id) or len(file_id) != filecrypt.FILE_ID_LENGTH:
abort(400, 'Invalid file ID format')
if not BASE64_RE.match(token) or len(token) != filecrypt.TOKEN_LENGTH:
abort(400, 'Invalid token format')
path = f'{app.config["SERVE_PATH"]}/{file_id}.enc'
if not os.path.isfile(path):
abort(403) # forbidden
size = filecrypt.payload_size(path)
range_header = re.match('^bytes=([0-9]+)-([0-9]*)$', request.headers.get('Range', ''))
if not range_header:
try:
generator = filecrypt.decrypt_generator(path, filename, token)
except ValueError: # MAC check failed
abort(403) # forbidden
response = Response(generator, mimetype='application/octet-stream')
response.headers['Content-Length'] = size
else:
range_start, range_end = range_header.groups()
range_start = int(range_start)
range_end = int(range_end) if range_end else size-1
if range_start < 0 or range_end >= size or range_start >= range_end:
abort(416) # range not satisfiable
try:
generator = filecrypt.decrypt_generator(path, filename, token, seek=range_start, end=range_end)
except ValueError: # MAC check failed
abort(403) # forbidden
response = Response(generator, status=206, mimetype='application/octet-stream')
response.headers['Content-Range'] = f'bytes {range_start}-{range_end}/{size}'
response.headers['Content-Length'] = range_end - range_start + 1
print(f'{request.remote_addr}: {file_id} OK')
response.headers['Accept-Ranges'] = 'bytes'
response.headers['Content-Disposition'] = f'attachment {filename}'
return response
@app.route('/<key_id>/<file_id>/<token>/<filehash>', methods=['POST'])
def upload(key_id, file_id, token, filehash):
if not BASE64_RE.match(file_id) or len(file_id) != filecrypt.FILE_ID_LENGTH:
abort(400, 'Invalid file ID format')
if not BASE64_RE.match(token) or len(token) != filecrypt.token_b64len(32):
abort(400, 'Invalid token format')
if not BASE64_RE.match(filehash) or len(filehash) != filecrypt.token_b64len(32):
abort(400, 'Invalid hash format')
if not BASE64_RE.match(key_id) or len(key_id) != filecrypt.token_b64len(32):
abort(400, 'Invalid key id format')
if request.content_length is None:
abort(411)
if request.content_length > app.config['MAX_UPLOAD_CHUNK_SIZE']:
abort(413)
if not key_id in upload_keys:
abort(403)
filehash = filecrypt.token_b64decode(filehash)
token = filecrypt.token_b64decode(token)
content_range = request.headers.get('Content-Range', 'NO CONTENT RANGE')
mac = hmac.new(upload_keys[key_id], digestmod='sha3_256')
mac.update(file_id.encode())
mac.update(filehash)
mac.update(content_range.encode())
if not hmac.compare_digest(mac.digest(), token):
abort(403)
path = f'{app.config["SERVE_PATH"]}/{file_id}.enc'
if os.path.isfile(path):
abort(409)
if 'chunk' not in request.files:
abort(400, 'Invalid file payload')
data = request.files['chunk'].read()
hash = hashlib.sha3_256()
hash.update(data)
if not hmac.compare_digest(hash.digest(), filehash):
abort(400)
tmp_path = f'{path}.uploading'
range_header = re.match('^bytes ([0-9]+)-([0-9]+)/([0-9]+|\*)$', content_range)
if not range_header:
if os.path.isfile(tmp_path):
os.remove(tmp_path)
with open(path, 'wb') as f:
f.write(data)
print(f'{request.remote_addr}: {file_id} UPLOAD')
return 'success', 200
else:
range_start, range_end, size = range_header.groups()
if size == '*':
abort(400, 'Content-range header if used must include total size')
try:
range_start, range_end, size = int(range_start), int(range_end), int(size)
except ValueError:
abort(400)
with open(tmp_path, 'ab') as f:
if range_start > f.tell():
abort(416)
f.truncate(range_start)
f.write(data)
if range_end+1 == size:
os.rename(tmp_path, path)
print(f'{request.remote_addr}: {file_id} UPLOAD')
return 'success', 200
return 'partial', 206
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