Catch SSL errors
[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 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)