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                         # 404 - Not found
 184                         # Either the provider has changed the API, or
 185                         # there is an error on the server
 186                         elif e.code == 404:
 187                                 raise DDNSNotFound(e.reason)
 188
 189                         # 500 - Internal Server Error
 190                         elif e.code == 500:
 191                                 raise DDNSInternalServerError(e.reason)
 192
 193                         # 503 - Service Unavailable
 194                         elif e.code == 503:
 195                                 raise DDNSServiceUnavailableError(e.reason)
 196
 197                         # Raise all other unhandled exceptions.
 198                         raise
 199
 200                 except urllib2.URLError, e:
 201                         if e.reason:
 202                                 # Name or service not known
 203                                 if e.reason.errno == -2:
 204                                         raise DDNSResolveError
 205
 206                                 # Network Unreachable (e.g. no IPv6 access)
 207                                 if e.reason.errno == 101:
 208                                         raise DDNSNetworkUnreachableError
 209
 210                                 # Connection Refused
 211                                 elif e.reason.errno == 111:
 212                                         raise DDNSConnectionRefusedError
 213
 214                         # Raise all other unhandled exceptions.
 215                         raise
 216
 217                 except socket.timeout, e:
 218                         logger.debug(_("Connection timeout"))
 219
 220                         raise DDNSConnectionTimeoutError
 221
 222         def _format_query_args(self, data):
 223                 args = []
 224
 225                 for k, v in data.items():
 226                         arg = "%s=%s" % (k, urllib.quote(v))
 227                         args.append(arg)
 228
 229                 return "&".join(args)
 230
 231         def _make_basic_auth_header(self, username, password):
 232                 authstring = "%s:%s" % (username, password)
 233
 234                 # Encode authorization data in base64.
 235                 authstring = base64.encodestring(authstring)
 236
 237                 # Remove any newline characters.
 238                 authstring = authstring.replace("\n", "")
 239
 240                 return authstring
 241
 242         def get_address(self, proto):
 243                 """
 244                         Returns the current IP address for
 245                         the given IP protocol.
 246                 """
 247                 try:
 248                         return self.__addresses[proto]
 249
 250                 # IP is currently unknown and needs to be retrieved.
 251                 except KeyError:
 252                         self.__addresses[proto] = address = \
 253                                 self._get_address(proto)
 254
 255                         return address
 256
 257         def _get_address(self, proto):
 258                 assert proto in ("ipv6", "ipv4")
 259
 260                 # IPFire 2 does not support IPv6.
 261                 if self.distro == "ipfire-2" and proto == "ipv6":
 262                         return
 263
 264                 # Check if the external IP address should be guessed from
 265                 # a remote server.
 266                 guess_ip = self.core.settings.get("guess_external_ip", "true")
 267                 guess_ip = guess_ip in ("true", "yes", "1")
 268
 269                 # If the external IP address should be used, we just do that.
 270                 if guess_ip:
 271                         return self.guess_external_ip_address(proto)
 272
 273                 # Get the local IP address.
 274                 local_ip_address = self.get_local_ip_address(proto)
 275
 276                 # If the local IP address is not usable, we must guess
 277                 # the correct IP address...
 278                 if not self._is_usable_ip_address(proto, local_ip_address):
 279                         local_ip_address = self.guess_external_ip_address(proto)
 280
 281                 return local_ip_address
 282
 283         def _is_usable_ip_address(self, proto, address):
 284                 """
 285                         Returns True is the local IP address is usable
 286                         for dynamic DNS (i.e. is not a RFC1918 address or similar).
 287                 """
 288                 if proto == "ipv4":
 289                         # This is not the most perfect solution to match
 290                         # these addresses, but instead of pulling in an entire
 291                         # library to handle the IP addresses better, we match
 292                         # with regular expressions instead.
 293                         matches = (
 294                                 # RFC1918 address space
 295                                 r"^10\.\d+\.\d+\.\d+$",
 296                                 r"^192\.168\.\d+\.\d+$",
 297                                 r"^172\.(1[6-9]|2[0-9]|31)\.\d+\.\d+$",
 298
 299                                 # Dual Stack Lite address space
 300                                 r"^100\.(6[4-9]|[7-9][0-9]|1[01][0-9]|12[0-7])\.\d+\.\d+$",
 301                         )
 302
 303                         for match in matches:
 304                                 m = re.match(match, address)
 305                                 if m is None:
 306                                         continue
 307
 308                                 # Found a match. IP address is not usable.
 309                                 return False
 310
 311                 # In all other cases, return OK.
 312                 return True
 313
 314         def resolve(self, hostname, proto=None):
 315                 addresses = []
 316
 317                 if proto is None:
 318                         family = 0
 319                 elif proto == "ipv6":
 320                         family = socket.AF_INET6
 321                 elif proto == "ipv4":
 322                         family = socket.AF_INET
 323                 else:
 324                         raise ValueError("Protocol not supported: %s" % proto)
 325
 326                 # Resolve the host address.
 327                 try:
 328                         response = socket.getaddrinfo(hostname, None, family)
 329                 except socket.gaierror, e:
 330                         # Name or service not known
 331                         if e.errno == -2:
 332                                 return []
 333
 334                         # Temporary failure in name resolution
 335                         elif e.errno == -3:
 336                                 raise DDNSResolveError(hostname)
 337
 338                         # No record for requested family available (e.g. no AAAA)
 339                         elif e.errno == -5:
 340                                 return []
 341
 342                         raise
 343
 344                 # Handle responses.
 345                 for family, socktype, proto, canonname, sockaddr in response:
 346                         # IPv6
 347                         if family == socket.AF_INET6:
 348                                 address, port, flow_info, scope_id = sockaddr
 349
 350                                 # Only use the global scope.
 351                                 if not scope_id == 0:
 352                                         continue
 353
 354                         # IPv4
 355                         elif family == socket.AF_INET:
 356                                 address, port = sockaddr
 357
 358                         # Ignore everything else...
 359                         else:
 360                                 continue
 361
 362                         # Add to repsonse list if not already in there.
 363                         if not address in addresses:
 364                                 addresses.append(address)
 365
 366                 return addresses
 367
 368         def _get_distro_identifier(self):
 369                 """
 370                         Returns a unique identifier for the distribution
 371                         we are running on.
 372                 """
 373                 os_release = self.__parse_os_release()
 374                 if os_release:
 375                         return os_release
 376
 377                 system_release = self.__parse_system_release()
 378                 if system_release:
 379                         return system_release
 380
 381                 # If nothing else could be found, we return
 382                 # just "unknown".
 383                 return "unknown"
 384
 385         def __parse_os_release(self):
 386                 """
 387                         Tries to parse /etc/os-release and
 388                         returns a unique distribution identifier
 389                         if the file exists.
 390                 """
 391                 try:
 392                         f = open("/etc/os-release", "r")
 393                 except IOError, e:
 394                         # File not found
 395                         if e.errno == 2:
 396                                 return
 397
 398                         raise
 399
 400                 os_release = {}
 401                 with f:
 402                         for line in f.readlines():
 403                                 m = re.match(r"^([A-Z\_]+)=(.*)$", line)
 404                                 if m is None:
 405                                         continue
 406
 407                                 os_release[m.group(1)] = m.group(2)
 408
 409                 try:
 410                         return "%(ID)s-%(VERSION_ID)s" % os_release
 411                 except KeyError:
 412                         return
 413
 414         def __parse_system_release(self):
 415                 """
 416                         Tries to parse /etc/system-release and
 417                         returns a unique distribution identifier
 418                         if the file exists.
 419                 """
 420                 try:
 421                         f = open("/etc/system-release", "r")
 422                 except IOError, e:
 423                         # File not found
 424                         if e.errno == 2:
 425                                 return
 426
 427                         raise
 428
 429                 with f:
 430                         # Read first line
 431                         line = f.readline()
 432
 433                         # Check for IPFire systems
 434                         m = re.match(r"^IPFire (\d).(\d+)", line)
 435                         if m:
 436                                 return "ipfire-%s" % m.group(1)