src/ddns/system.py

   1 #!/usr/bin/python
   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
  27 import urllib2
  28
  29 from __version__ import CLIENT_VERSION
  30 from .errors import *
  31 from i18n import _
  32
  33 # Initialize the logger.
  34 import logging
  35 logger = logging.getLogger("ddns.system")
  36 logger.propagate = 1
  37
  38 class DDNSSystem(object):
  39         """
  40                 The DDNSSystem class adds a layer of abstraction
  41                 between the ddns software and the system.
  42         """
  43
  44         # The default useragent.
  45         USER_AGENT = "IPFireDDNSUpdater/%s" % CLIENT_VERSION
  46
  47         def __init__(self, core):
  48                 # Connection to the core of the program.
  49                 self.core = core
  50
  51                 # Address cache.
  52                 self.__addresses = {}
  53
  54                 # Find out on which distribution we are running.
  55                 self.distro = self._get_distro_identifier()
  56                 logger.debug(_("Running on distribution: %s") % self.distro)
  57
  58         @property
  59         def proxy(self):
  60                 proxy = self.core.settings.get("proxy")
  61
  62                 # Strip http:// at the beginning.
  63                 if proxy and proxy.startswith("http://"):
  64                         proxy = proxy[7:]
  65
  66                 return proxy
  67
  68         def get_local_ip_address(self, proto):
  69                 # Legacy code for IPFire 2.
  70                 if self.distro == "ipfire-2" and proto == "ipv4":
  71                         try:
  72                                 with open("/var/ipfire/red/local-ipaddress") as f:
  73                                         return f.readline()
  74
  75                         except IOError, e:
  76                                 # File not found
  77                                 if e.errno == 2:
  78                                         return
  79
  80                                 raise
  81
  82                 # XXX TODO
  83                 raise NotImplementedError
  84
  85         def _guess_external_ip_address(self, url, timeout=10):
  86                 """
  87                         Sends a request to an external web server
  88                         to determine the current default IP address.
  89                 """
  90                 try:
  91                         response = self.send_request(url, timeout=timeout)
  92
  93                 # If the server could not be reached, we will return nothing.
  94                 except DDNSNetworkError:
  95                         return
  96
  97                 if not response.code == 200:
  98                         return
  99
 100                 match = re.search(r"^Your IP address is: (.*)$", response.read())
 101                 if match is None:
 102                         return
 103
 104                 return match.group(1)
 105
 106         def guess_external_ip_address(self, family, **kwargs):
 107                 if family == "ipv6":
 108                         url = "http://checkip6.dns.lightningwirelabs.com"
 109                 elif family == "ipv4":
 110                         url = "http://checkip4.dns.lightningwirelabs.com"
 111                 else:
 112                         raise ValueError("unknown address family")
 113
 114                 return self._guess_external_ip_address(url, **kwargs)
 115
 116         def send_request(self, url, method="GET", data=None, username=None, password=None, timeout=30):
 117                 assert method in ("GET", "POST")
 118
 119                 # Add all arguments in the data dict to the URL and escape them properly.
 120                 if method == "GET" and data:
 121                         query_args = self._format_query_args(data)
 122                         data = None
 123
 124                         if "?" in url:
 125                                 url = "%s&%s" % (url, query_args)
 126                         else:
 127                                 url = "%s?%s" % (url, query_args)
 128
 129                 logger.debug("Sending request (%s): %s" % (method, url))
 130                 if data:
 131                         logger.debug("  data: %s" % data)
 132
 133                 req = urllib2.Request(url, data=data)
 134
 135                 if username and password:
 136                         basic_auth_header = self._make_basic_auth_header(username, password)
 137                         req.add_header("Authorization", "Basic %s" % basic_auth_header)
 138
 139                 # Set the user agent.
 140                 req.add_header("User-Agent", self.USER_AGENT)
 141
 142                 # All requests should not be cached anywhere.
 143                 req.add_header("Pragma", "no-cache")
 144
 145                 # Set the upstream proxy if needed.
 146                 if self.proxy:
 147                         logger.debug("Using proxy: %s" % self.proxy)
 148
 149                         # Configure the proxy for this request.
 150                         req.set_proxy(self.proxy, "http")
 151
 152                 assert req.get_method() == method
 153
 154                 logger.debug(_("Request header:"))
 155                 for k, v in req.headers.items():
 156                         logger.debug("  %s: %s" % (k, v))
 157
 158                 try:
 159                         resp = urllib2.urlopen(req, timeout=timeout)
 160
 161                         # Log response header.
 162                         logger.debug(_("Response header (Status Code %s):") % resp.code)
 163                         for k, v in resp.info().items():
 164                                 logger.debug("  %s: %s" % (k, v))
 165
 166                         # Return the entire response object.
 167                         return resp
 168
 169                 except urllib2.HTTPError, e:
 170                         # Log response header.
 171                         logger.debug(_("Response header (Status Code %s):") % e.code)
 172                         for k, v in e.hdrs.items():
 173                                 logger.debug("  %s: %s" % (k, v))
 174
 175                         # 400 - Bad request
 176                         if e.code == 400:
 177                                 raise DDNSRequestError(e.reason)
 178
 179                         # 401 - Authorization Required
 180                         # 403 - Forbidden
 181                         elif e.code in (401, 403):
 182                                 raise DDNSAuthenticationError(e.reason)
 183
 184                         # 404 - Not found
 185                         # Either the provider has changed the API, or
 186                         # there is an error on the server
 187                         elif e.code == 404:
 188                                 raise DDNSNotFound(e.reason)
 189
 190                         # 500 - Internal Server Error
 191                         elif e.code == 500:
 192                                 raise DDNSInternalServerError(e.reason)
 193
 194                         # 503 - Service Unavailable
 195                         elif e.code == 503:
 196                                 raise DDNSServiceUnavailableError(e.reason)
 197
 198                         # Raise all other unhandled exceptions.
 199                         raise
 200
 201                 except urllib2.URLError, e:
 202                         if e.reason:
 203                                 # Handle SSL errors
 204                                 if isinstance(e.reason, ssl.SSLError):
 205                                         e = e.reason
 206
 207                                         if e.reason == "CERTIFICATE_VERIFY_FAILED":
 208                                                 raise DDNSCertificateError
 209
 210                                         # Raise all other SSL errors
 211                                         raise DDNSSSLError(e.reason)
 212
 213                                 # Name or service not known
 214                                 if e.reason.errno == -2:
 215                                         raise DDNSResolveError
 216
 217                                 # Network Unreachable (e.g. no IPv6 access)
 218                                 if e.reason.errno == 101:
 219                                         raise DDNSNetworkUnreachableError
 220
 221                                 # Connection Refused
 222                                 elif e.reason.errno == 111:
 223                                         raise DDNSConnectionRefusedError
 224
 225                                 # No route to host
 226                                 elif e.reason.errno == 113:
 227                                         raise DDNSNoRouteToHostError(req.host)
 228
 229                         # Raise all other unhandled exceptions.
 230                         raise
 231
 232                 except socket.timeout, e:
 233                         logger.debug(_("Connection timeout"))
 234
 235                         raise DDNSConnectionTimeoutError
 236
 237         def _format_query_args(self, data):
 238                 args = []
 239
 240                 for k, v in data.items():
 241                         arg = "%s=%s" % (k, urllib.quote(v))
 242                         args.append(arg)
 243
 244                 return "&".join(args)
 245
 246         def _make_basic_auth_header(self, username, password):
 247                 authstring = "%s:%s" % (username, password)
 248
 249                 # Encode authorization data in base64.
 250                 authstring = base64.encodestring(authstring)
 251
 252                 # Remove any newline characters.
 253                 authstring = authstring.replace("\n", "")
 254
 255                 return authstring
 256
 257         def get_address(self, proto):
 258                 """
 259                         Returns the current IP address for
 260                         the given IP protocol.
 261                 """
 262                 try:
 263                         return self.__addresses[proto]
 264
 265                 # IP is currently unknown and needs to be retrieved.
 266                 except KeyError:
 267                         self.__addresses[proto] = address = \
 268                                 self._get_address(proto)
 269
 270                         return address
 271
 272         def _get_address(self, proto):
 273                 assert proto in ("ipv6", "ipv4")
 274
 275                 # IPFire 2 does not support IPv6.
 276                 if self.distro == "ipfire-2" and proto == "ipv6":
 277                         return
 278
 279                 # Check if the external IP address should be guessed from
 280                 # a remote server.
 281                 guess_ip = self.core.settings.get("guess_external_ip", "true")
 282                 guess_ip = guess_ip in ("true", "yes", "1")
 283
 284                 # If the external IP address should be used, we just do that.
 285                 if guess_ip:
 286                         return self.guess_external_ip_address(proto)
 287
 288                 # Get the local IP address.
 289                 local_ip_address = self.get_local_ip_address(proto)
 290
 291                 # If the local IP address is not usable, we must guess
 292                 # the correct IP address...
 293                 if not self._is_usable_ip_address(proto, local_ip_address):
 294                         local_ip_address = self.guess_external_ip_address(proto)
 295
 296                 return local_ip_address
 297
 298         def _is_usable_ip_address(self, proto, address):
 299                 """
 300                         Returns True is the local IP address is usable
 301                         for dynamic DNS (i.e. is not a RFC1918 address or similar).
 302                 """
 303                 if proto == "ipv4":
 304                         # This is not the most perfect solution to match
 305                         # these addresses, but instead of pulling in an entire
 306                         # library to handle the IP addresses better, we match
 307                         # with regular expressions instead.
 308                         matches = (
 309                                 # RFC1918 address space
 310                                 r"^10\.\d+\.\d+\.\d+$",
 311                                 r"^192\.168\.\d+\.\d+$",
 312                                 r"^172\.(1[6-9]|2[0-9]|31)\.\d+\.\d+$",
 313
 314                                 # Dual Stack Lite address space
 315                                 r"^100\.(6[4-9]|[7-9][0-9]|1[01][0-9]|12[0-7])\.\d+\.\d+$",
 316                         )
 317
 318                         for match in matches:
 319                                 m = re.match(match, address)
 320                                 if m is None:
 321                                         continue
 322
 323                                 # Found a match. IP address is not usable.
 324                                 return False
 325
 326                 # In all other cases, return OK.
 327                 return True
 328
 329         def resolve(self, hostname, proto=None):
 330                 addresses = []
 331
 332                 if proto is None:
 333                         family = 0
 334                 elif proto == "ipv6":
 335                         family = socket.AF_INET6
 336                 elif proto == "ipv4":
 337                         family = socket.AF_INET
 338                 else:
 339                         raise ValueError("Protocol not supported: %s" % proto)
 340
 341                 # Resolve the host address.
 342                 try:
 343                         response = socket.getaddrinfo(hostname, None, family)
 344                 except socket.gaierror, e:
 345                         # Name or service not known
 346                         if e.errno == -2:
 347                                 return []
 348
 349                         # Temporary failure in name resolution
 350                         elif e.errno == -3:
 351                                 raise DDNSResolveError(hostname)
 352
 353                         # No record for requested family available (e.g. no AAAA)
 354                         elif e.errno == -5:
 355                                 return []
 356
 357                         raise
 358
 359                 # Handle responses.
 360                 for family, socktype, proto, canonname, sockaddr in response:
 361                         # IPv6
 362                         if family == socket.AF_INET6:
 363                                 address, port, flow_info, scope_id = sockaddr
 364
 365                                 # Only use the global scope.
 366                                 if not scope_id == 0:
 367                                         continue
 368
 369                         # IPv4
 370                         elif family == socket.AF_INET:
 371                                 address, port = sockaddr
 372
 373                         # Ignore everything else...
 374                         else:
 375                                 continue
 376
 377                         # Add to repsonse list if not already in there.
 378                         if not address in addresses:
 379                                 addresses.append(address)
 380
 381                 return addresses
 382
 383         def _get_distro_identifier(self):
 384                 """
 385                         Returns a unique identifier for the distribution
 386                         we are running on.
 387                 """
 388                 os_release = self.__parse_os_release()
 389                 if os_release:
 390                         return os_release
 391
 392                 system_release = self.__parse_system_release()
 393                 if system_release:
 394                         return system_release
 395
 396                 # If nothing else could be found, we return
 397                 # just "unknown".
 398                 return "unknown"
 399
 400         def __parse_os_release(self):
 401                 """
 402                         Tries to parse /etc/os-release and
 403                         returns a unique distribution identifier
 404                         if the file exists.
 405                 """
 406                 try:
 407                         f = open("/etc/os-release", "r")
 408                 except IOError, e:
 409                         # File not found
 410                         if e.errno == 2:
 411                                 return
 412
 413                         raise
 414
 415                 os_release = {}
 416                 with f:
 417                         for line in f.readlines():
 418                                 m = re.match(r"^([A-Z\_]+)=(.*)$", line)
 419                                 if m is None:
 420                                         continue
 421
 422                                 os_release[m.group(1)] = m.group(2)
 423
 424                 try:
 425                         return "%(ID)s-%(VERSION_ID)s" % os_release
 426                 except KeyError:
 427                         return
 428
 429         def __parse_system_release(self):
 430                 """
 431                         Tries to parse /etc/system-release and
 432                         returns a unique distribution identifier
 433                         if the file exists.
 434                 """
 435                 try:
 436                         f = open("/etc/system-release", "r")
 437                 except IOError, e:
 438                         # File not found
 439                         if e.errno == 2:
 440                                 return
 441
 442                         raise
 443
 444                 with f:
 445                         # Read first line
 446                         line = f.readline()
 447
 448                         # Check for IPFire systems
 449                         m = re.match(r"^IPFire (\d).(\d+)", line)
 450                         if m:
 451                                 return "ipfire-%s" % m.group(1)