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