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                         # Log response header.
 170                         logger.debug(_("Response header (Status Code %s):") % e.code)
 171                         for k, v in e.hdrs.items():
 172                                 logger.debug("  %s: %s" % (k, v))
 173
 174                         # 400 - Bad request
 175                         if e.code == 400:
 176                                 raise DDNSRequestError(e.reason)
 177
 178                         # 401 - Authorization Required
 179                         # 403 - Forbidden
 180                         elif e.code in (401, 403):
 181                                 raise DDNSAuthenticationError(e.reason)
 182
 183                         # 500 - Internal Server Error
 184                         elif e.code == 500:
 185                                 raise DDNSInternalServerError(e.reason)
 186
 187                         # 503 - Service Unavailable
 188                         elif e.code == 503:
 189                                 raise DDNSServiceUnavailableError(e.reason)
 190
 191                         # Raise all other unhandled exceptions.
 192                         raise
 193
 194                 except urllib2.URLError, e:
 195                         if e.reason:
 196                                 # Name or service not known
 197                                 if e.reason.errno == -2:
 198                                         raise DDNSResolveError
 199
 200                                 # Network Unreachable (e.g. no IPv6 access)
 201                                 if e.reason.errno == 101:
 202                                         raise DDNSNetworkUnreachableError
 203
 204                                 # Connection Refused
 205                                 elif e.reason.errno == 111:
 206                                         raise DDNSConnectionRefusedError
 207
 208                         # Raise all other unhandled exceptions.
 209                         raise
 210
 211                 except socket.timeout, e:
 212                         logger.debug(_("Connection timeout"))
 213
 214                         raise DDNSConnectionTimeoutError
 215
 216         def _format_query_args(self, data):
 217                 args = []
 218
 219                 for k, v in data.items():
 220                         arg = "%s=%s" % (k, urllib.quote(v))
 221                         args.append(arg)
 222
 223                 return "&".join(args)
 224
 225         def _make_basic_auth_header(self, username, password):
 226                 authstring = "%s:%s" % (username, password)
 227
 228                 # Encode authorization data in base64.
 229                 authstring = base64.encodestring(authstring)
 230
 231                 # Remove any newline characters.
 232                 authstring = authstring.replace("\n", "")
 233
 234                 return authstring
 235
 236         def get_address(self, proto):
 237                 """
 238                         Returns the current IP address for
 239                         the given IP protocol.
 240                 """
 241                 try:
 242                         return self.__addresses[proto]
 243
 244                 # IP is currently unknown and needs to be retrieved.
 245                 except KeyError:
 246                         self.__addresses[proto] = address = \
 247                                 self._get_address(proto)
 248
 249                         return address
 250
 251         def _get_address(self, proto):
 252                 assert proto in ("ipv6", "ipv4")
 253
 254                 # IPFire 2 does not support IPv6.
 255                 if self.distro == "ipfire-2" and proto == "ipv6":
 256                         return
 257
 258                 # Check if the external IP address should be guessed from
 259                 # a remote server.
 260                 guess_ip = self.core.settings.get("guess_external_ip", "true")
 261                 guess_ip = guess_ip in ("true", "yes", "1")
 262
 263                 # If the external IP address should be used, we just do that.
 264                 if guess_ip:
 265                         return self.guess_external_ip_address(proto)
 266
 267                 # Get the local IP address.
 268                 local_ip_address = self.get_local_ip_address(proto)
 269
 270                 # If the local IP address is not usable, we must guess
 271                 # the correct IP address...
 272                 if not self._is_usable_ip_address(proto, local_ip_address):
 273                         local_ip_address = self.guess_external_ip_address(proto)
 274
 275                 return local_ip_address
 276
 277         def _is_usable_ip_address(self, proto, address):
 278                 """
 279                         Returns True is the local IP address is usable
 280                         for dynamic DNS (i.e. is not a RFC1918 address or similar).
 281                 """
 282                 if proto == "ipv4":
 283                         # This is not the most perfect solution to match
 284                         # these addresses, but instead of pulling in an entire
 285                         # library to handle the IP addresses better, we match
 286                         # with regular expressions instead.
 287                         matches = (
 288                                 # RFC1918 address space
 289                                 r"^10\.\d+\.\d+\.\d+$",
 290                                 r"^192\.168\.\d+\.\d+$",
 291                                 r"^172\.(1[6-9]|2[0-9]|31)\.\d+\.\d+$",
 292
 293                                 # Dual Stack Lite address space
 294                                 r"^100\.(6[4-9]|[7-9][0-9]|1[01][0-9]|12[0-7])\.\d+\.\d+$",
 295                         )
 296
 297                         for match in matches:
 298                                 m = re.match(match, address)
 299                                 if m is None:
 300                                         continue
 301
 302                                 # Found a match. IP address is not usable.
 303                                 return False
 304
 305                 # In all other cases, return OK.
 306                 return True
 307
 308         def resolve(self, hostname, proto=None):
 309                 addresses = []
 310
 311                 if proto is None:
 312                         family = 0
 313                 elif proto == "ipv6":
 314                         family = socket.AF_INET6
 315                 elif proto == "ipv4":
 316                         family = socket.AF_INET
 317                 else:
 318                         raise ValueError("Protocol not supported: %s" % proto)
 319
 320                 # Resolve the host address.
 321                 try:
 322                         response = socket.getaddrinfo(hostname, None, family)
 323                 except socket.gaierror, e:
 324                         # Name or service not known
 325                         if e.errno == -2:
 326                                 return []
 327
 328                         # Temporary failure in name resolution
 329                         elif e.errno == -3:
 330                                 raise DDNSResolveError(hostname)
 331
 332                         # No record for requested family available (e.g. no AAAA)
 333                         elif e.errno == -5:
 334                                 return []
 335
 336                         raise
 337
 338                 # Handle responses.
 339                 for family, socktype, proto, canonname, sockaddr in response:
 340                         # IPv6
 341                         if family == socket.AF_INET6:
 342                                 address, port, flow_info, scope_id = sockaddr
 343
 344                                 # Only use the global scope.
 345                                 if not scope_id == 0:
 346                                         continue
 347
 348                         # IPv4
 349                         elif family == socket.AF_INET:
 350                                 address, port = sockaddr
 351
 352                         # Ignore everything else...
 353                         else:
 354                                 continue
 355
 356                         # Add to repsonse list if not already in there.
 357                         if not address in addresses:
 358                                 addresses.append(address)
 359
 360                 return addresses
 361
 362         def _get_distro_identifier(self):
 363                 """
 364                         Returns a unique identifier for the distribution
 365                         we are running on.
 366                 """
 367                 os_release = self.__parse_os_release()
 368                 if os_release:
 369                         return os_release
 370
 371                 system_release = self.__parse_system_release()
 372                 if system_release:
 373                         return system_release
 374
 375                 # If nothing else could be found, we return
 376                 # just "unknown".
 377                 return "unknown"
 378
 379         def __parse_os_release(self):
 380                 """
 381                         Tries to parse /etc/os-release and
 382                         returns a unique distribution identifier
 383                         if the file exists.
 384                 """
 385                 try:
 386                         f = open("/etc/os-release", "r")
 387                 except IOError, e:
 388                         # File not found
 389                         if e.errno == 2:
 390                                 return
 391
 392                         raise
 393
 394                 os_release = {}
 395                 with f:
 396                         for line in f.readlines():
 397                                 m = re.match(r"^([A-Z\_]+)=(.*)$", line)
 398                                 if m is None:
 399                                         continue
 400
 401                                 os_release[m.group(1)] = m.group(2)
 402
 403                 try:
 404                         return "%(ID)s-%(VERSION_ID)s" % os_release
 405                 except KeyError:
 406                         return
 407
 408         def __parse_system_release(self):
 409                 """
 410                         Tries to parse /etc/system-release and
 411                         returns a unique distribution identifier
 412                         if the file exists.
 413                 """
 414                 try:
 415                         f = open("/etc/system-release", "r")
 416                 except IOError, e:
 417                         # File not found
 418                         if e.errno == 2:
 419                                 return
 420
 421                         raise
 422
 423                 with f:
 424                         # Read first line
 425                         line = f.readline()
 426
 427                         # Check for IPFire systems
 428                         m = re.match(r"^IPFire (\d).(\d+)", line)
 429                         if m:
 430                                 return "ipfire-%s" % m.group(1)