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1 | # ldd - DNS implementation in Python |
2 | # Copyright (C) 2006 Fredrik Tolf <fredrik@dolda2000.com> |
3 | # |
4 | # This program is free software; you can redistribute it and/or modify |
5 | # it under the terms of the GNU General Public License as published by |
6 | # the Free Software Foundation; either version 2 of the License, or |
7 | # (at your option) any later version. |
8 | # |
9 | # This program is distributed in the hope that it will be useful, |
10 | # but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
12 | # GNU General Public License for more details. |
13 | # |
14 | # You should have received a copy of the GNU General Public License |
15 | # along with this program; if not, write to the Free Software |
16 | # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
17 | |
18 | import socket |
19 | import threading |
20 | import select |
21 | import errno |
22 | import logging |
23 | import time |
24 | |
25 | import proto |
26 | import rec |
27 | import dn |
28 | import resolver |
29 | |
30 | logger = logging.getLogger("ldd.server") |
31 | |
32 | class dnsserver: |
33 | class socklistener(threading.Thread): |
34 | def __init__(self, server): |
35 | threading.Thread.__init__(self) |
36 | self.server = server |
37 | self.alive = True |
38 | |
39 | class sender: |
40 | def __init__(self, addr, sk): |
41 | self.addr = addr |
42 | self.sk = sk |
43 | |
44 | def send(self, pkt): |
45 | logger.debug("sending response to %04x", pkt.qid) |
46 | self.sk.sendto(pkt.encode(), self.addr) |
47 | |
48 | def run(self): |
49 | while self.alive: |
50 | p = select.poll() |
51 | for af, sk in self.server.sockets: |
52 | p.register(sk.fileno(), select.POLLIN) |
53 | try: |
54 | fds = p.poll(1000) |
55 | except select.error, e: |
56 | if e[0] == errno.EINTR: |
57 | continue |
58 | raise |
59 | for fd, event in fds: |
60 | if event & select.POLLIN == 0: |
61 | continue |
62 | for af, sk in self.server.sockets: |
63 | if sk.fileno() == fd: |
64 | break |
65 | else: |
66 | continue |
67 | req, addr = sk.recvfrom(65536) |
68 | try: |
69 | pkt = proto.decodepacket(req) |
70 | except proto.malformedpacket, inst: |
71 | resp = proto.packet(inst.qid, ["resp"]) |
72 | resp.rescode = proto.FORMERR |
73 | sk.sendto(resp.encode(), addr) |
74 | else: |
75 | logger.debug("got request (%04x) from %s", pkt.qid, addr[0]) |
76 | pkt.addr = (af,) + addr |
77 | self.server.queuereq(pkt, dnsserver.socklistener.sender(addr, sk)) |
78 | |
79 | def stop(self): |
80 | self.alive = False |
81 | |
82 | class dispatcher(threading.Thread): |
83 | def __init__(self, server): |
84 | threading.Thread.__init__(self) |
85 | self.server = server |
86 | self.alive = True |
87 | |
88 | def run(self): |
89 | while self.alive: |
90 | req = self.server.dequeuereq() |
91 | if req is not None: |
92 | pkt, sender = req |
93 | resp = self.server.handle(pkt) |
94 | if resp is None: |
95 | resp = proto.responsefor(pkt, proto.SERVFAIL) |
96 | sender.send(resp) |
97 | |
98 | class queuemonitor(threading.Thread): |
99 | def __init__(self, server): |
100 | threading.Thread.__init__(self) |
101 | self.server = server |
102 | |
103 | def run(self): |
104 | while(self.server.running): |
105 | self.server.queuelock.acquire() |
106 | if len(self.server.queue) > 0: |
107 | peeked = self.server.queue[0] |
108 | else: |
109 | peeked = None |
110 | self.server.queuelock.release() |
111 | if peeked is not None: |
112 | if time.time() - peeked[0] > 1: |
113 | newdsp = dnsserver.dispatcher(self.server) |
114 | self.server.dispatchers += [newdsp] |
115 | newdsp.start() |
116 | logger.debug("starting new dispatcher, there are now %i", len(self.server.dispatchers)) |
117 | time.sleep(1) |
118 | |
119 | def __init__(self): |
120 | self.sockets = [] |
121 | self.queue = [] |
122 | self.zones = [] |
123 | self.listener = None |
124 | self.dispatchers = [] |
125 | self.running = False |
126 | self.queuelock = threading.Condition() |
127 | self.knownkeys = [] |
128 | |
129 | def handle(self, pkt): |
130 | resp = None |
131 | |
132 | if len(self.knownkeys) > 0: |
133 | import dnssec |
134 | dnssec.tsigverify(pkt, self.knownkeys) |
135 | |
136 | for query in pkt.qlist: |
137 | match = None |
138 | for zone in self.zones: |
139 | if query.name in zone.origin: |
140 | if match is None: |
141 | match = zone |
142 | elif len(zone.origin) > len(match.origin): |
143 | match = zone |
144 | if match is None: |
145 | return None |
146 | else: |
147 | curresp = match.handle(query, pkt) |
148 | if resp is None: |
149 | resp = curresp |
150 | else: |
151 | resp.merge(curresp) |
152 | |
153 | if resp is not None and resp.tsigctx is not None and not resp.signed: |
154 | resp.tsigctx.signpkt(resp) |
155 | |
156 | return resp |
157 | |
158 | def addsock(self, af, socket): |
159 | self.sockets += [(af, socket)] |
160 | |
161 | def addzone(self, zone): |
162 | self.zones += [zone] |
163 | |
164 | def queuereq(self, req, sender): |
165 | self.queuelock.acquire() |
166 | self.queue += [(time.time(), req, sender)] |
167 | logger.debug("queue length+: %i", len(self.queue)) |
168 | self.queuelock.notify() |
169 | self.queuelock.release() |
170 | |
171 | def dequeuereq(self): |
172 | self.queuelock.acquire() |
173 | if len(self.queue) == 0: |
174 | self.queuelock.wait() |
175 | if len(self.queue) > 0: |
176 | ret = self.queue[0] |
177 | self.queue = self.queue[1:] |
178 | else: |
179 | ret = None |
180 | logger.debug("queue length-: %i", len(self.queue)) |
181 | self.queuelock.release() |
182 | if ret is None: |
183 | return None |
184 | else: |
185 | return ret[1:] |
186 | |
187 | def start(self): |
188 | if self.running: |
189 | raise Exception("already running") |
190 | lst = dnsserver.socklistener(self) |
191 | self.listener = lst |
192 | lst.start() |
193 | for i in xrange(10): |
194 | newdsp = dnsserver.dispatcher(self) |
195 | self.dispatchers += [newdsp] |
196 | newdsp.start() |
197 | self.running = True |
198 | self.monitor = dnsserver.queuemonitor(self) |
199 | self.monitor.start() |
200 | |
201 | def stop(self): |
202 | self.listener.stop() |
203 | self.listener.join() |
204 | self.listener = None |
205 | for dsp in self.dispatchers: |
206 | dsp.alive = False |
207 | self.queuelock.acquire() |
208 | self.queuelock.notifyAll() |
209 | self.queuelock.release() |
210 | for dsp in self.dispatchers + []: |
211 | dsp.join() |
212 | self.dispatchers.remove(dsp) |
213 | self.running = False |
214 | self.monitor = None |
215 | |
216 | def resolver(self, addr = None): |
217 | class myres(resolver.resolver): |
218 | def __init__(self, server, addr): |
219 | self.server = server |
220 | self.addr = addr |
221 | def resolve(self, packet): |
222 | if self.addr is not None: |
223 | packet.addr = self.addr |
224 | packet.setflags(["internal"]) |
225 | return self.server.handle(packet) |
226 | return myres(self, addr) |
227 | |
228 | class zone: |
229 | def __init__(self, origin, handler): |
230 | if type(origin) == str: |
231 | self.origin = dn.fromstring(origin) |
232 | self.origin.rooted = True |
233 | else: |
234 | self.origin = origin |
235 | self.handler = handler |
236 | |
237 | def handle(self, query, pkt): |
238 | resp = self.handler.handle(query, pkt, self.origin) |
239 | return resp |
240 | |
241 | class authzone(zone): |
242 | def __init__(self, aurecres, *args): |
243 | self.aurecres = aurecres |
244 | zone.__init__(self, *args) |
245 | |
246 | def handle(self, query, pkt): |
247 | resp = zone.handle(self, query, pkt) |
248 | if not "internal" in pkt.flags: |
249 | if resp is None: |
250 | resp = proto.responsefor(pkt) |
251 | soa = zone.handle(self, rec.rrhead(self.origin, "SOA"), pkt) |
252 | resp.aulist += soa.anlist |
253 | resp.rescode = proto.NXDOMAIN |
254 | else: |
255 | resolver.resolvecnames(resp, self.aurecres) |
256 | nsrecs = zone.handle(self, rec.rrhead(self.origin, "NS"), pkt) |
257 | if nsrecs is not None: |
258 | resp.aulist += nsrecs.anlist |
259 | for rr in nsrecs.anlist: |
260 | resolver.resolveadditional(resp, rr, self.aurecres) |
261 | else: |
262 | if resp is None: |
263 | return None |
264 | resp.setflags(["auth"]) |
265 | return resp |
266 | |
267 | class handler: |
268 | def handle(self, query, pkt, origin): |
269 | return None |
270 | |
271 | class forwarder(handler): |
272 | def __init__(self, nameserver, timeout = 2000, retries = 3): |
273 | self.nameserver = nameserver |
274 | self.timeout = timeout |
275 | self.retries = retries |
276 | |
277 | def handle(self, query, pkt, origin): |
278 | sk = socket.socket(self.nameserver[0], socket.SOCK_DGRAM) |
279 | sk.bind(("", 0)) |
280 | p = select.poll() |
281 | p.register(sk.fileno(), select.POLLIN) |
282 | for i in range(self.retries): |
283 | sk.sendto(pkt.encode(), self.nameserver[1:]) |
284 | fds = p.poll(self.timeout) |
285 | if (sk.fileno(), select.POLLIN) in fds: |
286 | break |
287 | else: |
288 | return None |
289 | resp = sk.recv(65536) |
290 | resp = proto.decodepacket(resp) |
291 | return resp |
292 | |
293 | class recurser(handler): |
294 | def __init__(self, resolver): |
295 | self.resolver = resolver |
296 | |
297 | def handle(self, query, pkt, origin): |
298 | try: |
299 | resp = self.resolver.resolve(pkt) |
300 | except resolver.error: |
301 | return None |
302 | return resp |
303 | |
304 | class chain(handler): |
305 | def __init__(self, chain): |
306 | self.chain = chain |
307 | |
308 | def add(self, handler): |
309 | self.chain += [handler] |
310 | |
311 | def handle(self, *args): |
312 | for h in self.chain: |
313 | resp = h.handle(*args) |
314 | if resp is not None: |
315 | return resp |
316 | return None |
317 | |