| 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 | |