src/ddns/system.py

   1 #!/usr/bin/python3
   2 ###############################################################################
   3 #                                                                             #
   4 # ddns - A dynamic DNS client for IPFire                                      #
   5 # Copyright (C) 2012 IPFire development team                                  #
   6 #                                                                             #
   7 # This program is free software: you can redistribute it and/or modify        #
   8 # it under the terms of the GNU General Public License as published by        #
   9 # the Free Software Foundation, either version 3 of the License, or           #
  10 # (at your option) any later version.                                         #
  11 #                                                                             #
  12 # This program is distributed in the hope that it will be useful,             #
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of              #
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               #
  15 # GNU General Public License for more details.                                #
  16 #                                                                             #
  17 # You should have received a copy of the GNU General Public License           #
  18 # along with this program.  If not, see <http://www.gnu.org/licenses/>.       #
  19 #                                                                             #
  20 ###############################################################################
  21
  22 import base64
  23 import re
  24 import ssl
  25 import socket
  26 import urllib.request
  27 import urllib.parse
  28 import urllib.error
  29
  30 from .__version__ import CLIENT_VERSION
  31 from .errors import *
  32 from .i18n import _
  33
  34 # Initialize the logger.
  35 import logging
  36 logger = logging.getLogger("ddns.system")
  37 logger.propagate = 1
  38
  39 class DDNSSystem(object):
  40         """
  41                 The DDNSSystem class adds a layer of abstraction
  42                 between the ddns software and the system.
  43         """
  44
  45         # The default useragent.
  46         USER_AGENT = "IPFireDDNSUpdater/%s" % CLIENT_VERSION
  47
  48         def __init__(self, core):
  49                 # Connection to the core of the program.
  50                 self.core = core
  51
  52                 # Address cache.
  53                 self.__addresses = {}
  54
  55                 # Find out on which distribution we are running.
  56                 self.distro = self._get_distro_identifier()
  57                 logger.debug(_("Running on distribution: %s") % self.distro)
  58
  59         @property
  60         def proxy(self):
  61                 proxy = self.core.settings.get("proxy")
  62
  63                 # Strip http:// at the beginning.
  64                 if proxy and proxy.startswith("http://"):
  65                         proxy = proxy[7:]
  66
  67                 return proxy
  68
  69         def get_local_ip_address(self, proto):
  70                 ip_address = self._get_local_ip_address(proto)
  71
  72                 # Check if the IP address is usable and only return it then
  73                 if self._is_usable_ip_address(proto, ip_address):
  74                         return ip_address
  75
  76         def _get_local_ip_address(self, proto):
  77                 # Legacy code for IPFire 2.
  78                 if self.distro == "ipfire-2" and proto == "ipv4":
  79                         try:
  80                                 with open("/var/ipfire/red/local-ipaddress") as f:
  81                                         return f.readline()
  82
  83                         except IOError as e:
  84                                 # File not found
  85                                 if e.errno == 2:
  86                                         return
  87
  88                                 raise
  89
  90                 # XXX TODO
  91                 raise NotImplementedError
  92
  93         def _guess_external_ip_address(self, url, timeout=10):
  94                 """
  95                         Sends a request to an external web server
  96                         to determine the current default IP address.
  97                 """
  98                 try:
  99                         response = self.send_request(url, timeout=timeout)
 100
 101                 # If the server could not be reached, we will return nothing.
 102                 except DDNSNetworkError:
 103                         return
 104
 105                 if not response.code == 200:
 106                         return
 107
 108                 match = re.search(b"^Your IP address is: (.*)$", response.read())
 109                 if match is None:
 110                         return
 111
 112                 return match.group(1).decode()
 113
 114         def guess_external_ip_address(self, family, **kwargs):
 115                 if family == "ipv6":
 116                         url = "https://checkip6.dns.lightningwirelabs.com"
 117                 elif family == "ipv4":
 118                         url = "https://checkip4.dns.lightningwirelabs.com"
 119                 else:
 120                         raise ValueError("unknown address family")
 121
 122                 return self._guess_external_ip_address(url, **kwargs)
 123
 124         def send_request(self, url, method="GET", data=None, username=None, password=None, timeout=30):
 125                 assert method in ("GET", "POST")
 126
 127                 # Add all arguments in the data dict to the URL and escape them properly.
 128                 if method == "GET" and data:
 129                         query_args = self._format_query_args(data)
 130                         data = None
 131
 132                         if "?" in url:
 133                                 url = "%s&%s" % (url, query_args)
 134                         else:
 135                                 url = "%s?%s" % (url, query_args)
 136
 137                 logger.debug("Sending request (%s): %s" % (method, url))
 138                 if data:
 139                         logger.debug("  data: %s" % data)
 140
 141                 req = urllib.request.Request(url, data=data)
 142
 143                 if username and password:
 144                         basic_auth_header = self._make_basic_auth_header(username, password)
 145                         req.add_header("Authorization", "Basic %s" % basic_auth_header.decode())
 146
 147                 # Set the user agent.
 148                 req.add_header("User-Agent", self.USER_AGENT)
 149
 150                 # All requests should not be cached anywhere.
 151                 req.add_header("Pragma", "no-cache")
 152
 153                 # Set the upstream proxy if needed.
 154                 if self.proxy:
 155                         logger.debug("Using proxy: %s" % self.proxy)
 156
 157                         # Configure the proxy for this request.
 158                         req.set_proxy(self.proxy, "http")
 159
 160                 assert req.get_method() == method
 161
 162                 logger.debug(_("Request header:"))
 163                 for k, v in req.headers.items():
 164                         logger.debug("  %s: %s" % (k, v))
 165
 166                 try:
 167                         resp = urllib.request.urlopen(req, timeout=timeout)
 168
 169                         # Log response header.
 170                         logger.debug(_("Response header (Status Code %s):") % resp.code)
 171                         for k, v in resp.info().items():
 172                                 logger.debug("  %s: %s" % (k, v))
 173
 174                         # Return the entire response object.
 175                         return resp
 176
 177                 except urllib.error.HTTPError as e:
 178                         # Log response header.
 179                         logger.debug(_("Response header (Status Code %s):") % e.code)
 180                         for k, v in e.hdrs.items():
 181                                 logger.debug("  %s: %s" % (k, v))
 182
 183                         # 400 - Bad request
 184                         if e.code == 400:
 185                                 raise DDNSRequestError(e.reason)
 186
 187                         # 401 - Authorization Required
 188                         # 403 - Forbidden
 189                         elif e.code in (401, 403):
 190                                 raise DDNSAuthenticationError(e.reason)
 191
 192                         # 404 - Not found
 193                         # Either the provider has changed the API, or
 194                         # there is an error on the server
 195                         elif e.code == 404:
 196                                 raise DDNSNotFound(e.reason)
 197
 198                         # 429 - Too Many Requests
 199                         elif e.code == 429:
 200                                 raise DDNSTooManyRequests(e.reason)
 201
 202                         # 500 - Internal Server Error
 203                         elif e.code == 500:
 204                                 raise DDNSInternalServerError(e.reason)
 205
 206                         # 503 - Service Unavailable
 207                         elif e.code == 503:
 208                                 raise DDNSServiceUnavailableError(e.reason)
 209
 210                         # Raise all other unhandled exceptions.
 211                         raise
 212
 213                 except urllib.error.URLError as e:
 214                         if e.reason:
 215                                 # Handle SSL errors
 216                                 if isinstance(e.reason, ssl.SSLError):
 217                                         e = e.reason
 218
 219                                         if e.reason == "CERTIFICATE_VERIFY_FAILED":
 220                                                 raise DDNSCertificateError
 221
 222                                         # Raise all other SSL errors
 223                                         raise DDNSSSLError(e.reason)
 224
 225                                 # Name or service not known
 226                                 if e.reason.errno == -2:
 227                                         raise DDNSResolveError
 228
 229                                 # Cannot assign requested address
 230                                 elif e.reason.errno == 99:
 231                                         raise DDNSNetworkUnreachableError
 232
 233                                 # Network Unreachable (e.g. no IPv6 access)
 234                                 elif e.reason.errno == 101:
 235                                         raise DDNSNetworkUnreachableError
 236
 237                                 # Connection Refused
 238                                 elif e.reason.errno == 111:
 239                                         raise DDNSConnectionRefusedError
 240
 241                                 # No route to host
 242                                 elif e.reason.errno == 113:
 243                                         raise DDNSNoRouteToHostError(req.host)
 244
 245                         # Raise all other unhandled exceptions.
 246                         raise
 247
 248                 except socket.timeout as e:
 249                         logger.debug(_("Connection timeout"))
 250
 251                         raise DDNSConnectionTimeoutError
 252
 253         def _format_query_args(self, data):
 254                 args = []
 255
 256                 for k, v in data.items():
 257                         arg = "%s=%s" % (k, urllib.parse.quote(v))
 258                         args.append(arg)
 259
 260                 return "&".join(args)
 261
 262         def _make_basic_auth_header(self, username, password):
 263                 authstring = "%s:%s" % (username, password)
 264
 265                 # Encode authorization data in base64.
 266                 authstring = base64.b64encode(authstring.encode())
 267
 268                 return authstring
 269
 270         def get_address(self, proto):
 271                 """
 272                         Returns the current IP address for
 273                         the given IP protocol.
 274                 """
 275                 try:
 276                         return self.__addresses[proto]
 277
 278                 # IP is currently unknown and needs to be retrieved.
 279                 except KeyError:
 280                         self.__addresses[proto] = address = \
 281                                 self._get_address(proto)
 282
 283                         return address
 284
 285         def _get_address(self, proto):
 286                 assert proto in ("ipv6", "ipv4")
 287
 288                 # IPFire 2 does not support IPv6.
 289                 if self.distro == "ipfire-2" and proto == "ipv6":
 290                         return
 291
 292                 # Check if the external IP address should be guessed from
 293                 # a remote server.
 294                 guess_ip = self.core.settings.get("guess_external_ip", "true")
 295                 guess_ip = guess_ip in ("true", "yes", "1")
 296
 297                 # Get the local IP address.
 298                 local_ip_address = None
 299
 300                 if not guess_ip:
 301                         try:
 302                                 local_ip_address = self.get_local_ip_address(proto)
 303                         except NotImplementedError:
 304                                 logger.warning(_("Falling back to check the IP address with help of a public server"))
 305
 306                 # If no local IP address could be determined, we will fall back to the guess
 307                 # it with help of an external server...
 308                 if not local_ip_address:
 309                         local_ip_address = self.guess_external_ip_address(proto)
 310
 311                 return local_ip_address
 312
 313         def _is_usable_ip_address(self, proto, address):
 314                 """
 315                         Returns True is the local IP address is usable
 316                         for dynamic DNS (i.e. is not a RFC1918 address or similar).
 317                 """
 318                 if proto == "ipv4":
 319                         # This is not the most perfect solution to match
 320                         # these addresses, but instead of pulling in an entire
 321                         # library to handle the IP addresses better, we match
 322                         # with regular expressions instead.
 323                         matches = (
 324                                 # RFC1918 address space
 325                                 r"^10\.\d+\.\d+\.\d+$",
 326                                 r"^192\.168\.\d+\.\d+$",
 327                                 r"^172\.(1[6-9]|2[0-9]|31)\.\d+\.\d+$",
 328
 329                                 # Dual Stack Lite address space
 330                                 r"^100\.(6[4-9]|[7-9][0-9]|1[01][0-9]|12[0-7])\.\d+\.\d+$",
 331                         )
 332
 333                         for match in matches:
 334                                 m = re.match(match, address)
 335                                 if m is None:
 336                                         continue
 337
 338                                 # Found a match. IP address is not usable.
 339                                 return False
 340
 341                 # In all other cases, return OK.
 342                 return True
 343
 344         def resolve(self, hostname, proto=None):
 345                 addresses = []
 346
 347                 if proto is None:
 348                         family = 0
 349                 elif proto == "ipv6":
 350                         family = socket.AF_INET6
 351                 elif proto == "ipv4":
 352                         family = socket.AF_INET
 353                 else:
 354                         raise ValueError("Protocol not supported: %s" % proto)
 355
 356                 # Resolve the host address.
 357                 try:
 358                         response = socket.getaddrinfo(hostname, None, family)
 359                 except socket.gaierror as e:
 360                         # Name or service not known
 361                         if e.errno == -2:
 362                                 return []
 363
 364                         # Temporary failure in name resolution
 365                         elif e.errno == -3:
 366                                 raise DDNSResolveError(hostname)
 367
 368                         # No record for requested family available (e.g. no AAAA)
 369                         elif e.errno == -5:
 370                                 return []
 371
 372                         raise
 373
 374                 # Handle responses.
 375                 for family, socktype, proto, canonname, sockaddr in response:
 376                         # IPv6
 377                         if family == socket.AF_INET6:
 378                                 address, port, flow_info, scope_id = sockaddr
 379
 380                                 # Only use the global scope.
 381                                 if not scope_id == 0:
 382                                         continue
 383
 384                         # IPv4
 385                         elif family == socket.AF_INET:
 386                                 address, port = sockaddr
 387
 388                         # Ignore everything else...
 389                         else:
 390                                 continue
 391
 392                         # Add to repsonse list if not already in there.
 393                         if address not in addresses:
 394                                 addresses.append(address)
 395
 396                 return addresses
 397
 398         def _get_distro_identifier(self):
 399                 """
 400                         Returns a unique identifier for the distribution
 401                         we are running on.
 402                 """
 403                 os_release = self.__parse_os_release()
 404                 if os_release:
 405                         return os_release
 406
 407                 system_release = self.__parse_system_release()
 408                 if system_release:
 409                         return system_release
 410
 411                 # If nothing else could be found, we return
 412                 # just "unknown".
 413                 return "unknown"
 414
 415         def __parse_os_release(self):
 416                 """
 417                         Tries to parse /etc/os-release and
 418                         returns a unique distribution identifier
 419                         if the file exists.
 420                 """
 421                 try:
 422                         f = open("/etc/os-release", "r")
 423                 except IOError as e:
 424                         # File not found
 425                         if e.errno == 2:
 426                                 return
 427
 428                         raise
 429
 430                 os_release = {}
 431                 with f:
 432                         for line in f.readlines():
 433                                 m = re.match(r"^([A-Z\_]+)=(.*)$", line)
 434                                 if m is None:
 435                                         continue
 436
 437                                 os_release[m.group(1)] = m.group(2)
 438
 439                 try:
 440                         return "%(ID)s-%(VERSION_ID)s" % os_release
 441                 except KeyError:
 442                         return
 443
 444         def __parse_system_release(self):
 445                 """
 446                         Tries to parse /etc/system-release and
 447                         returns a unique distribution identifier
 448                         if the file exists.
 449                 """
 450                 try:
 451                         f = open("/etc/system-release", "r")
 452                 except IOError as e:
 453                         # File not found
 454                         if e.errno == 2:
 455                                 return
 456
 457                         raise
 458
 459                 with f:
 460                         # Read first line
 461                         line = f.readline()
 462
 463                         # Check for IPFire systems
 464                         m = re.match(r"^IPFire (\d).(\d+)", line)
 465                         if m:
 466                                 return "ipfire-%s" % m.group(1)