cab2942aba4c101eb4da157225527e238d99c579
[oddments/ddns.git] / 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)