doorstatus/statusd.py
2020-07-09 20:09:36 +02:00

297 lines
9.8 KiB
Python
Executable file

#!/usr/bin/python3
# file: statusd.py
# date: 26.07.2019
# email: berhsi@web.de
# Status server, listening for door status updates. The IPv4 address and port
# to listen on are configurable, by default localhost:10001 is used. The
# connection is secured by TLS and client side authentication.
import json
import logging
import os
import socket
import ssl
import sys
from time import time, sleep
import configparser
def certs_readable(config):
'''
checks at start, if the needed certificates defined (no nullstring) and
readable.
param 1: dictionary
return: boolean
'''
for i in (config['server']['key'], config['server']['cert'],
config['client']['cert']):
if i == '' or os.access(i, os.R_OK) is False:
logging.error('Cannot read {}'.format(i))
return False
return True
def print_config(config):
'''
Logs the config with level debug.
'''
logging.debug('Using config:')
for section in config.sections():
logging.debug('Section {}'.format(section))
for i in config[section]:
logging.debug(' {}: {}'.format(i, config[section][i]))
def print_ciphers(cipherlist):
'''
Prints the list of allowed ciphers.
param1: dictionary
return: boolean
'''
print('Available ciphers')
for i in cipherlist:
print('\n')
for j in i.keys():
print('{}: {}'.format(j, i[j]))
print('\n')
def display_peercert(cert):
'''
Displays the values of a given certificate.
param1: dictionary
return: boolean
'''
for i in cert.keys():
print('{}:'.format(i))
if i in ('subject', 'issuer'):
for j in cert[i]:
print('\t{}'.format(j))
else:
print('\t{}'.format(cert[i]))
def receive_buffer_is_valid(raw_data):
'''
Checks validity of the received buffer contents.
param 1: byte
return: boolean
'''
if raw_data in (b'\x00', b'\x01'):
logging.debug('Argument is valid: {}'.format(raw_data))
return True
logging.debug('Argument is not valid: {}'.format(raw_data))
return False
def change_status(raw_data, api):
'''
Write the new status together with a timestamp into the Space API JSON.
param 1: byte
param 2: string
return: boolean
'''
logging.debug('Change status API')
# todo: use walrus operator := when migrating to python >= 3.8
data = read_api(api)
if data is False:
return False
status, timestamp = set_values(raw_data)
if os.access(api, os.W_OK):
logging.debug('API file is writable')
with open(api, 'w') as api_file:
logging.debug('API file open successfull')
data["state"]["open"] = status
data["state"]["lastchange"] = timestamp
try:
json.dump(data, api_file, indent=4)
except Exception as e:
logging.error('Failed to change API file')
logging.error('{}'.format(e))
logging.debug('API file changed')
else:
logging.error('API file is not writable. Wrong permissions?')
return False
logging.info('Status successfull changed to {}'.format(status))
return True
def read_api(api):
'''
Reads the Space API JSON into a dict. Returns the dict on success and
False on failure.
param 1: string
return: dict or boolean
'''
logging.debug('Open API file: {}'.format(api))
# return early if the API JSON cannot be read
if not os.access(api, os.R_OK):
logging.error('Failed to read API file')
return False
logging.debug('API is readable')
with open(api, 'r') as api_file:
logging.debug('API file successfully opened')
try:
api_json_data = json.load(api_file)
logging.debug('API file read successfull')
except Exception as e:
logging.error('Failed to read API file: {}'.format(e))
return False
return api_json_data
def set_values(raw_data):
'''
Create a timestamp, changes the value of the given byte into a string
and returns both.
param 1: byte
return: tuple
'''
status = "true" if raw_data == b'\x01' else "false"
timestamp = str(time()).split('.')[0]
logging.debug('Set values for timestamp: {} and status: {}'.format(
timestamp, status))
return (status, timestamp)
def main():
'''
The main function - open a socket, create a ssl context, load certs and
listen for connections. At SSL context we set only one available cipher
suite and disable compression.
OP_NO_COMPRESSION: prevention against CRIME attack
OP_DONT_ISERT_EMPTY_FRAGMENTS: prevention agains CBC 4 attack
(cve-2011-3389)
'''
loglevel = logging.WARNING
formatstring = '%(asctime)s: %(levelname)s: %(message)s'
logging.basicConfig(format=formatstring, level=loglevel)
default_config = {
'general': {
'timeout': 3.0,
'loglevel': 'warning'
},
'server': {
'host': 'localhost',
'port': 10001,
'cert': './certs/server.crt',
'key': './certs/server.key'
},
'client': {
'cert': './certs/client.crt'
},
'api': {
'api': './api',
'template': './api_template'
}
}
configfile = './statusd.conf'
config = configparser.ConfigParser()
config.read_dict(default_config)
if not config.read(configfile):
logging.warning('Configuration file %s not found or not readable. Using default values.',
configfile)
logger = logging.getLogger()
if not config['general']['loglevel'] in ('critical', 'error', 'warning', 'info', 'debug'):
logging.warning('Invalid loglevel %s given. Using default level %s.',
config['general']['loglevel'],
default_config['general']['loglevel'])
config.set('general', 'loglevel', default_config['general']['loglevel'])
logger.setLevel(config['general']['loglevel'].upper())
print_config(config)
# todo: zertifikate sollten nur lesbar sein!
if not certs_readable(config):
logging.error('Cert check failed\nExit')
sys.exit(1)
context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
context.verify_mode = ssl.CERT_REQUIRED
context.load_cert_chain(certfile=config['server']['cert'],
keyfile=config['server']['key'])
context.load_verify_locations(cafile=config['client']['cert'])
context.set_ciphers('EECDH+AESGCM') # only ciphers for tls 1.2 and 1.3
context.options = ssl.OP_CIPHER_SERVER_PREFERENCE
# ensure, compression is disabled (disabled by default anyway at the moment)
context.options |= ssl.OP_NO_COMPRESSION
logging.debug('SSL context created')
# print_ciphers(context.get_ciphers())
with socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) as mySocket:
logging.debug('Socket created')
try:
mySocket.bind((config['server']['host'], int(config['server']['port'])))
mySocket.listen(5)
except Exception as e:
logging.error('Unable to bind and listen')
logging.error('{}'.format(e))
sys.exit(1)
logging.info('Listening on {} at Port {}'.format(config['server']['host'],
config['server']['port']))
while True:
try:
fromSocket, fromAddr = mySocket.accept()
logging.info('Client connected: {}:{}'.format(fromAddr[0], fromAddr[1]))
try:
fromSocket.settimeout(float(config['general']['timeout']))
logging.debug('Connection timeout set to {}'.format(
config['general']['timeout']))
except Exception:
logging.error('Cannot set timeout to {}'.format(
config['general']['timeout']))
try:
conn = context.wrap_socket(fromSocket, server_side=True)
conn.settimeout(float(config['general']['timeout']))
except socket.timeout:
logging.error('Socket timeout')
except Exception as e:
logging.error('Connection failed: {}'.format(e))
logging.info('Connection established')
logging.info('Peer certificate commonName: {}'.format(
conn.getpeercert()['subject'][5][0][1]))
logging.debug('Peer certificate serialNumber: {}'.format(
conn.getpeercert()['serialNumber']))
raw_data = conn.recv(1)
if receive_buffer_is_valid(raw_data) is True:
if change_status(raw_data, config['api']['api']) is True:
logging.debug('Send {} back'.format(raw_data))
conn.send(raw_data)
# change_status returns false:
else:
logging.info('Failed to change status')
if conn:
conn.send(b'\x03')
# receive_handle returns false:
else:
logging.info('Invalid argument received: {}'.format(raw_data))
logging.debug('Send {} back'.format(b'\x03'))
if conn:
conn.send(b'\x03')
sleep(0.1) # protection against dos
except KeyboardInterrupt:
logging.info('Exit')
sys.exit(1)
except Exception as e:
logging.error('{}'.format(e))
continue
return 0
if __name__ == '__main__':
main()