313 lines
11 KiB
Python
Executable file
313 lines
11 KiB
Python
Executable file
#!/usr/bin/python3
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# file: apistatusd.py
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# date: 26.07.2019
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# email: berhsi@web.de
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# Status server, listening for door status updates. The IPv4 address and port
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# to listen on are configurable, by default localhost:10001 is used. The
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# connection is secured by TLS and client side authentication.
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import json
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import logging
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import os
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import socket
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import ssl
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import sys
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from time import time, sleep
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import configparser
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def certs_readable(config):
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'''
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checks at start, if the needed certificates defined (no nullstring) and
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readable.
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param 1: dictionary
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return: boolean
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'''
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for i in (config['server']['key'], config['server']['cert'],
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config['client']['cert']):
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if i == '' or os.access(i, os.R_OK) is False:
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logging.error('Cannot read {}'.format(i))
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return False
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return True
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def print_config(config):
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'''
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Logs the config with level debug.
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'''
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logging.debug('Using config:')
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for section in config.sections():
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logging.debug('Section {}'.format(section))
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for i in config[section]:
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logging.debug(' {}: {}'.format(i, config[section][i]))
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def print_ciphers(cipherlist):
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'''
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Prints the list of allowed ciphers.
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param1: dictionary
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return: boolean
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'''
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logging.debug('Available ciphers')
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for i in cipherlist:
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for j in i.keys():
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if j in ('name', 'protocol'):
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logging.debug('{}: {}'.format(j, i[j]))
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def print_context(ctx):
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'''
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Prints the ssl settings for the given ssl context.
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param1: context object
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'''
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logging.debug('----------- context ----------------')
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logging.debug('Minimum version ssl: {}'.format(ctx.minimum_version))
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logging.debug('Maximum version ssl: {}'.format(ctx.maximum_version))
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logging.debug('SSL options enabled: {}'.format(ctx.options))
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logging.debug('Protocol: {}'.format(ctx.protocol))
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logging.debug('Verify flags certificates: {}'.format(ctx.verify_flags))
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logging.debug('Verify mode: {}'.format(ctx.verify_mode))
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print_ciphers(ctx.get_ciphers())
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logging.debug('------------------------------------')
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def display_peercert(cert):
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'''
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Displays the values of a given certificate.
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param1: dictionary or none
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'''
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if cert == None:
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logging.debug('Peer does not offer a certificate')
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elif len(cert) == 0:
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logging.debug('Peer certificate was not valid')
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else:
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logging.debug('Peer certificate commonName: {}'.format(
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cert['subject'][5][0][1]))
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logging.debug('Peer certificate serialNumber: {}'.format(
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cert['serialNumber']))
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logging.debug('Peer certificate notBefore: {}'.format(
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cert['notBefore']))
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logging.debug('Peer certificate notAfter: {}'.format(
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cert['notAfter']))
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def receive_buffer_is_valid(raw_data):
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'''
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Checks validity of the received buffer contents.
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param 1: byte object
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return: boolean
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'''
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if raw_data.decode('utf-8', 'strict') in ('0', '1'):
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logging.debug('Argument is valid: {}'.format(raw_data))
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return True
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logging.debug('Argument is not valid: {}'.format(raw_data))
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return False
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def change_status(raw_data, api):
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'''
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Write the new status together with a timestamp into the Space API JSON.
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param 1: byte object
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param 2: string
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return: boolean
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'''
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logging.debug('Change status API')
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# todo: use walrus operator := when migrating to python >= 3.8
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data = read_api(api)
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if data is False:
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return False
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status, timestamp = set_values(raw_data)
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if os.access(api, os.W_OK):
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logging.debug('API file is writable')
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with open(api, 'w') as api_file:
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logging.debug('API file open successfull')
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data["state"]["open"] = status
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data["state"]["lastchange"] = timestamp
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try:
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json.dump(data, api_file, indent=4)
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except Exception as e:
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logging.error('Failed to change API file')
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logging.error('{}'.format(e))
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return False
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logging.debug('API file changed')
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else:
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logging.error('API file is not writable. Wrong permissions?')
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return False
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logging.info('Status successfull changed to {}'.format(status))
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return True
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def read_api(api):
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'''
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Reads the Space API JSON into a dict. Returns the dict on success and
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False on failure.
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param 1: string
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return: dict or boolean
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'''
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logging.debug('Open API file: {}'.format(api))
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# return early if the API JSON cannot be read
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if not os.access(api, os.R_OK):
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logging.error('Failed to read API file')
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return False
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logging.debug('API is readable')
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with open(api, 'r') as api_file:
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logging.debug('API file successfully opened')
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try:
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api_json_data = json.load(api_file)
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logging.debug('API file read successfull')
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except Exception as e:
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logging.error('Failed to read API file: {}'.format(e))
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return False
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return api_json_data
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def set_values(raw_data):
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'''
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Create a timestamp, changes the value of the given byte into a string
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and returns both.
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param 1: byte object
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return: tuple
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'''
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status = True if raw_data.decode('utf-8', 'strict') == '1' else False
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timestamp = int(str(time()).split('.')[0])
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logging.debug('Set values for timestamp: {} and status: {}'.format(
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str(timestamp), str(status)))
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return (status, timestamp)
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def main():
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'''
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The main function - open a socket, create a ssl context, load certs and
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listen for connections. At SSL context we set only one available cipher
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suite and disable compression.
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OP_NO_COMPRESSION: prevention against CRIME attack
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OP_DONT_ISERT_EMPTY_FRAGMENTS: prevention agains CBC 4 attack
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(cve-2011-3389)
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'''
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answer = '3'.encode(encoding='utf-8', errors='strict')
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loglevel = logging.WARNING
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formatstring = '%(asctime)s: %(levelname)s: %(message)s'
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logging.basicConfig(format=formatstring, level=loglevel)
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default_config = {
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'general': {
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'timeout': 3.0,
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'loglevel': 'warning'
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},
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'server': {
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'host': 'localhost',
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'port': 10001,
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'cert': './certs/server.crt',
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'key': './certs/server.key'
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},
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'client': {
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'cert': './certs/client.crt'
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},
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'api': {
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'api': './api',
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'template': './api_template'
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}
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}
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configfile = './apistatusd.conf'
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config = configparser.ConfigParser()
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config.read_dict(default_config)
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if not config.read(configfile):
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logging.warning('Configuration file %s not found or not readable. Using default values.',
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configfile)
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logger = logging.getLogger()
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if not config['general']['loglevel'] in ('critical', 'error', 'warning', 'info', 'debug'):
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logging.warning('Invalid loglevel %s given. Using default level %s.',
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config['general']['loglevel'],
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default_config['general']['loglevel'])
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config.set('general', 'loglevel', default_config['general']['loglevel'])
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logger.setLevel(config['general']['loglevel'].upper())
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print_config(config)
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# todo: zertifikate sollten nur lesbar sein!
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if not certs_readable(config):
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logging.error('Cert check failed\nExit')
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sys.exit(1)
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context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
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context.verify_mode = ssl.CERT_OPTIONAL
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context.load_cert_chain(certfile=config['server']['cert'],
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keyfile=config['server']['key'])
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context.load_verify_locations(cafile=config['client']['cert'])
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context.options = ssl.OP_CIPHER_SERVER_PREFERENCE
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# ensure, compression is disabled (disabled by default anyway at the moment)
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context.options |= ssl.OP_NO_COMPRESSION
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logging.debug('SSL context created')
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print_context(context)
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with socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) as mySocket:
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logging.debug('Socket created')
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mySocket.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
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keep = mySocket.getsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE)
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logging.debug('Socket keepalive: {}'.format(keep))
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try:
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mySocket.bind((config['server']['host'], int(config['server']['port'])))
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mySocket.listen(5)
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except Exception as e:
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logging.error('Unable to bind and listen')
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logging.error('{}'.format(e))
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sys.exit(1)
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logging.info('Listening on {} at Port {}'.format(config['server']['host'],
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config['server']['port']))
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while True:
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try:
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fromSocket, fromAddr = mySocket.accept()
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logging.info('Client connected: {}:{}'.format(fromAddr[0], fromAddr[1]))
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try:
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fromSocket.settimeout(float(config['general']['timeout']))
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logging.debug('Connection timeout set to {}'.format(
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config['general']['timeout']))
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except Exception:
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logging.error('Cannot set timeout to {}'.format(
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config['general']['timeout']))
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try:
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conn = context.wrap_socket(fromSocket, server_side=True)
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conn.settimeout(float(config['general']['timeout']))
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except socket.timeout:
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logging.error('Socket timeout')
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continue
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except Exception as e:
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logging.error('Connection failed: {}'.format(e))
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continue
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logging.info('Connection established')
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try:
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cert = conn.getpeercert(binary_form=False)
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display_peercert(cert)
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except ValueError:
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logging.debug('SSL handshake has not been done yet')
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except Exception as e:
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logging.debug('Unexpected error: {}'.format(e))
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raw_data = conn.recv(1)
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if receive_buffer_is_valid(raw_data) is True:
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if change_status(raw_data, config['api']['api']) is True:
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answer = raw_data
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if conn:
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logging.debug('Send {} back'.format(raw_data))
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conn.send(answer)
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sleep(0.1) # protection against dos
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except KeyboardInterrupt:
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logging.info('Keyboard interrupt received')
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sys.exit(1)
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except Exception as e:
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logging.error('{}'.format(e))
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continue
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return 0
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if __name__ == '__main__':
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main()
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