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1 | #!/usr/bin/python |
2 | ############################################################################### | |
3 | # # | |
4 | # IPFire.org - A linux based firewall # | |
5 | # Copyright (C) 2016 Michael Tremer # | |
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 argparse | |
23 | import datetime | |
24 | import daemon | |
25 | import logging | |
26 | import logging.handlers | |
27 | import re | |
28 | import signal | |
29 | import subprocess | |
30 | ||
31 | import inotify.adapters | |
32 | ||
33 | def setup_logging(loglevel=logging.INFO): | |
34 | log = logging.getLogger("dhcp") | |
35 | log.setLevel(loglevel) | |
36 | ||
37 | handler = logging.handlers.SysLogHandler(address="/dev/log", facility="daemon") | |
38 | handler.setLevel(loglevel) | |
39 | ||
40 | formatter = logging.Formatter("%(name)s[%(process)d]: %(message)s") | |
41 | handler.setFormatter(formatter) | |
42 | ||
43 | log.addHandler(handler) | |
44 | ||
45 | return log | |
46 | ||
47 | log = logging.getLogger("dhcp") | |
48 | ||
49 | class UnboundDHCPLeasesBridge(object): | |
50 | def __init__(self, dhcp_leases_file, unbound_leases_file): | |
51 | self.leases_file = dhcp_leases_file | |
52 | ||
53 | self.unbound = UnboundConfigWriter(unbound_leases_file) | |
54 | self.running = False | |
55 | ||
56 | def run(self): | |
57 | log.info("Unbound DHCP Leases Bridge started on %s" % self.leases_file) | |
58 | self.running = True | |
59 | ||
60 | # Initially read leases file | |
61 | self.update_dhcp_leases() | |
62 | ||
63 | i = inotify.adapters.Inotify([self.leases_file]) | |
64 | ||
65 | for event in i.event_gen(): | |
66 | # End if we are requested to terminate | |
67 | if not self.running: | |
68 | break | |
69 | ||
70 | if event is None: | |
71 | continue | |
72 | ||
73 | header, type_names, watch_path, filename = event | |
74 | ||
75 | # Update leases after leases file has been modified | |
76 | if "IN_MODIFY" in type_names: | |
77 | self.update_dhcp_leases() | |
78 | ||
79 | log.info("Unbound DHCP Leases Bridge terminated") | |
80 | ||
81 | def update_dhcp_leases(self): | |
82 | log.info("Reading DHCP leases from %s" % self.leases_file) | |
83 | ||
84 | leases = DHCPLeases(self.leases_file) | |
85 | self.unbound.update_dhcp_leases(leases) | |
86 | ||
87 | def terminate(self): | |
88 | self.running = False | |
89 | ||
90 | ||
91 | class DHCPLeases(object): | |
92 | regex_leaseblock = re.compile(r"lease (?P<ipaddr>\d+\.\d+\.\d+\.\d+) {(?P<config>[\s\S]+?)\n}") | |
93 | ||
94 | def __init__(self, path): | |
95 | self.path = path | |
96 | ||
97 | self._leases = self._parse() | |
98 | ||
99 | def __iter__(self): | |
100 | return iter(self._leases) | |
101 | ||
102 | def _parse(self): | |
103 | leases = [] | |
104 | ||
105 | with open(self.path) as f: | |
106 | # Read entire leases file | |
107 | data = f.read() | |
108 | ||
109 | for match in self.regex_leaseblock.finditer(data): | |
110 | block = match.groupdict() | |
111 | ||
112 | ipaddr = block.get("ipaddr") | |
113 | config = block.get("config") | |
114 | ||
115 | properties = self._parse_block(config) | |
116 | ||
117 | # Skip any abandoned leases | |
118 | if not "hardware" in properties: | |
119 | continue | |
120 | ||
121 | lease = Lease(ipaddr, properties) | |
122 | ||
123 | # Check if a lease for this Ethernet address already | |
124 | # exists in the list of known leases. If so replace | |
125 | # if with the most recent lease | |
126 | for i, l in enumerate(leases): | |
127 | if l.hwaddr == lease.hwaddr: | |
128 | leases[i] = max(lease, l) | |
129 | break | |
130 | ||
131 | else: | |
132 | leases.append(lease) | |
133 | ||
134 | return leases | |
135 | ||
136 | def _parse_block(self, block): | |
137 | properties = {} | |
138 | ||
139 | for line in block.splitlines(): | |
140 | if not line: | |
141 | continue | |
142 | ||
143 | # Remove trailing ; from line | |
144 | if line.endswith(";"): | |
145 | line = line[:-1] | |
146 | ||
147 | # Invalid line if it doesn't end with ; | |
148 | else: | |
149 | continue | |
150 | ||
151 | # Remove any leading whitespace | |
152 | line = line.lstrip() | |
153 | ||
154 | # We skip all options and sets | |
155 | if line.startswith("option") or line.startswith("set"): | |
156 | continue | |
157 | ||
158 | # Split by first space | |
159 | key, val = line.split(" ", 1) | |
160 | properties[key] = val | |
161 | ||
162 | return properties | |
163 | ||
164 | ||
165 | class Lease(object): | |
166 | def __init__(self, ipaddr, properties): | |
167 | self.ipaddr = ipaddr | |
168 | self._properties = properties | |
169 | ||
170 | def __repr__(self): | |
171 | return "<%s %s for %s (%s)>" % (self.__class__.__name__, | |
172 | self.ipaddr, self.hwaddr, self.hostname) | |
173 | ||
174 | def __eq__(self, other): | |
175 | return self.ipaddr == other.ipaddr and self.hwaddr == other.hwaddr | |
176 | ||
177 | def __gt__(self, other): | |
178 | if not self.ipaddr == other.ipaddr: | |
179 | return | |
180 | ||
181 | if not self.hwaddr == other.hwaddr: | |
182 | return | |
183 | ||
184 | return self.time_starts > other.time_starts | |
185 | ||
186 | @property | |
187 | def binding_state(self): | |
188 | state = self._properties.get("binding") | |
189 | ||
190 | if state: | |
191 | state = state.split(" ", 1) | |
192 | return state[1] | |
193 | ||
194 | @property | |
195 | def active(self): | |
196 | return self.binding_state == "active" | |
197 | ||
198 | @property | |
199 | def hwaddr(self): | |
200 | hardware = self._properties.get("hardware") | |
201 | ||
202 | if not hardware: | |
203 | return | |
204 | ||
205 | ethernet, address = hardware.split(" ", 1) | |
206 | ||
207 | return address | |
208 | ||
209 | @property | |
210 | def hostname(self): | |
211 | hostname = self._properties.get("client-hostname") | |
212 | ||
213 | # Remove any "" | |
214 | if hostname: | |
215 | hostname = hostname.replace("\"", "") | |
216 | ||
217 | return hostname | |
218 | ||
219 | @property | |
220 | def domain(self): | |
221 | return "local" # XXX | |
222 | ||
223 | @property | |
224 | def fqdn(self): | |
225 | return "%s.%s" % (self.hostname, self.domain) | |
226 | ||
227 | @staticmethod | |
228 | def _parse_time(s): | |
229 | return datetime.datetime.strptime(s, "%w %Y/%m/%d %H:%M:%S") | |
230 | ||
231 | @property | |
232 | def time_starts(self): | |
233 | starts = self._properties.get("starts") | |
234 | ||
235 | if starts: | |
236 | return self._parse_time(starts) | |
237 | ||
238 | @property | |
239 | def time_ends(self): | |
240 | ends = self._properties.get("ends") | |
241 | ||
242 | if not ends or ends == "never": | |
243 | return | |
244 | ||
245 | return self._parse_time(ends) | |
246 | ||
247 | @property | |
248 | def expired(self): | |
249 | if not self.time_ends: | |
250 | return self.time_starts > datetime.datetime.utcnow() | |
251 | ||
252 | return self.time_starts > datetime.datetime.utcnow() > self.time_ends | |
253 | ||
254 | @property | |
255 | def rrset(self): | |
256 | return [ | |
257 | # Forward record | |
258 | (self.fqdn, "IN A", self.ipaddr), | |
259 | ||
260 | # Reverse record | |
261 | (self.ipaddr, "IN PTR", self.fqdn), | |
262 | ] | |
263 | ||
264 | ||
265 | class UnboundConfigWriter(object): | |
266 | def __init__(self, path): | |
267 | self.path = path | |
268 | ||
269 | self._cached_leases = [] | |
270 | ||
271 | def update_dhcp_leases(self, leases): | |
272 | # Strip all non-active or expired leases | |
273 | leases = [l for l in leases if l.active and not l.expired] | |
274 | ||
275 | # Find any leases that have expired or do not exist any more | |
276 | removed_leases = [l for l in self._cached_leases if l.expired or l not in leases] | |
277 | ||
278 | # Find any leases that have been added | |
279 | new_leases = [l for l in leases if l not in self._cached_leases] | |
280 | ||
281 | # End here if nothing has changed | |
282 | if not new_leases and not removed_leases: | |
283 | return | |
284 | ||
285 | self._cached_leases = leases | |
286 | ||
287 | # Write out all leases | |
288 | self.write_dhcp_leases(leases) | |
289 | ||
290 | # Update unbound about changes | |
291 | for l in removed_leases: | |
292 | self._control("local_data_remove", l.fqdn) | |
293 | ||
294 | for l in new_leases: | |
295 | for rr in l.rrset: | |
296 | self._control("local_data", *rr) | |
297 | ||
298 | ||
299 | def write_dhcp_leases(self, leases): | |
300 | with open(self.path, "w") as f: | |
301 | for l in leases: | |
302 | for rr in l.rrset: | |
303 | f.write("local-data: \"%s\"\n" % " ".join(rr)) | |
304 | ||
305 | def _control(self, *args): | |
306 | command = ["unbound-control", "-q"] | |
307 | command.extend(args) | |
308 | ||
309 | try: | |
310 | subprocess.check_call(command) | |
311 | ||
312 | # Log any errors | |
313 | except subprocess.CalledProcessError as e: | |
314 | log.critical("Could not run %s, error code: %s: %s" % ( | |
315 | " ".join(command), e.returncode, e.output)) | |
316 | ||
317 | ||
318 | if __name__ == "__main__": | |
319 | parser = argparse.ArgumentParser(description="Bridge for DHCP Leases and Unbound DNS") | |
320 | ||
321 | # Daemon Stuff | |
322 | parser.add_argument("--daemon", "-d", action="store_true", | |
323 | help="Launch as daemon in background") | |
324 | parser.add_argument("--verbose", "-v", action="count", help="Be more verbose") | |
325 | ||
326 | # Paths | |
327 | parser.add_argument("--dhcp-leases", default="/var/state/dhcp/dhcpd.leases", | |
328 | metavar="PATH", help="Path to the DHCPd leases file") | |
329 | parser.add_argument("--unbound-leases", default="/etc/unbound/dhcp-leases.conf", | |
330 | metavar="PATH", help="Path to the unbound configuration file") | |
331 | ||
332 | # Parse command line arguments | |
333 | args = parser.parse_args() | |
334 | ||
335 | # Setup logging | |
336 | if args.verbose == 1: | |
337 | loglevel = logging.INFO | |
338 | elif args.verbose >= 2: | |
339 | loglevel = logging.DEBUG | |
340 | else: | |
341 | loglevel = logging.WARN | |
342 | ||
343 | setup_logging(loglevel) | |
344 | ||
345 | bridge = UnboundDHCPLeasesBridge(args.dhcp_leases, args.unbound_leases) | |
346 | ||
347 | ctx = daemon.DaemonContext(detach_process=args.daemon) | |
348 | ctx.signal_map = { | |
349 | signal.SIGHUP : bridge.update_dhcp_leases, | |
350 | signal.SIGTERM : bridge.terminate, | |
351 | } | |
352 | ||
353 | with ctx: | |
354 | bridge.run() |