-
Notifications
You must be signed in to change notification settings - Fork 0
/
DNSserver.py
executable file
·266 lines (223 loc) · 8.96 KB
/
DNSserver.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
#!/usr/bin/env python2
import sys
#sys.path.append("./dnspython")
#sys.path.append("./dnslib")
#sys.path.append("./python-daemon")
#sys.path.append("./pylockfile")
#from dns import rdatatype, resolver
import time
#import multiprocessing.pool
import argparse
import datetime
import threading
import traceback
import SocketServer
import os.path
import signal
import logging
import pickle
import dnslib
import daemon
import daemon.pidfile
#from dnslib import *
PORT = 53
PIDFILE = os.path.abspath(r'./server.pid')
CACHE_FILE = os.path.abspath(r"./cache.db")
class BaseRequestHandler(SocketServer.BaseRequestHandler):
def __init__(self, request, client_address, server):
SocketServer.BaseRequestHandler.__init__(self, request,\
client_address, server)
self.server = server
return
def get_data(self):
raise NotImplementedError
def send_data(self, data):
raise NotImplementedError
def handle(self):
now = datetime.datetime.utcnow().strftime('%Y-%m-%d %H:%M:%S.%f')
logging.info('Got request: \n\n%s request %s (%s %s):',\
self.__class__.__name__[:3],\
now, self.client_address[0], self.client_address[1])
try:
data = self.get_data()
logging.debug('RAW data(%d): %s', len(data), data.encode('hex'))
# repr(data).replace('\\x', '')[1:-1]
self.process_DNS_query(data)
#self.send_data(dns_response(data))
except Exception:
traceback.print_exc(file=sys.stderr)
def process_DNS_query(self, data):
# Must be overidden
pass
class TCPRequestHandler(BaseRequestHandler):
def get_data(self):
data = self.request.recv(8192)
sz = int(data[:2].encode('hex'), 16)
if sz < len(data) - 2:
raise Exception("Wrong size of TCP packet")
elif sz > len(data) - 2:
raise Exception("Too big TCP packet")
return data[2:]
def send_data(self, data):
sz = hex(len(data))[2:].zfill(4).decode('hex')
return self.request.sendall(sz + data)
class UDPRequestHandler(BaseRequestHandler):
def get_data(self):
return self.request[0]
def send_data(self, data):
return self.request[1].sendto(data, self.client_address)
class DNSUDPRequestHandler(UDPRequestHandler):
def process_DNS_query(self, data):
logging.debug("parsing DNS query")
# parse the request
request = dnslib.DNSRecord.parse(data)
logging.info('Lookup request: %s', request)
# lookup the record
self.dns_resolve(request)
def dns_resolve(self, request):
logging.debug("resolving")
qname_str = str(request.q.qname)
qtype = request.q.qtype
answer, additional_ans = self.dns_do_resolve(qname_str, qtype)
self.reply_query(answer, request, additional_ans)
def dns_do_resolve(self, qname, qtype):
# override
logging.error('dns_do_resolve not implemented %s, %s', qname, qtype)
return ((dnslib.RCODE.NOTIMP, []), [])
def reply_query(self, answer, request, additional_ans=None):
DNS_response = self.prepare_reply(answer, request, additional_ans)
self.send_data(DNS_response)
def prepare_reply(self, answer, request, additional_ans=None, ttl=10):
# pack anwsers
qname = request.q.qname
qtype = request.q.qtype
qt = dnslib.QTYPE[qtype]
rcode = answer[1]
reply = dnslib.DNSRecord(dnslib.DNSHeader(\
id=request.header.id, qr=1, aa=1, ra=1,\
rcode=rcode), q=request.q)
record_class = getattr(dnslib, str(qt))
for a in answer[0]:
reply.add_answer(dnslib.RR(rname=qname, rtype=qtype,\
rclass=1, ttl=ttl, rdata=record_class(a)))
for ans in additional_ans:
qtype = ans[2]
qt = dnslib.QTYPE[qtype]
rcode = ans[1]
record_class = getattr(dnslib, str(qt))
for a in ans[0]:
reply.add_answer(dnslib.RR(rname=qname, rtype=qtype,\
rclass=1, ttl=ttl, rdata=record_class(a)))
return reply.pack()
class DNSserver(object):
def __init__(self, port=PORT, serverClass=DNSUDPRequestHandler):
self.port = port
self.serverClass = serverClass
self.cache = {}
def cache_manager(self):
# reload cache saved to disk
if os.path.isfile(CACHE_FILE):
with open(CACHE_FILE, 'rb') as f:
file_cache = pickle.load(f)
for k in file_cache:
self.cache[k] = file_cache[k]
logging.info('Loaded %d cache entries from disk', len(self.cache))
while True:
time.sleep(60)
with open(CACHE_FILE, 'wb+') as f:
pickle.dump(self.cache, f)
logging.info('Autosaved %d cache entries to disk', len(self.cache))
def do_start_server(self, bind_addr='0.0.0.0'):
logging.info("Starting nameserver...")
servers = [
SocketServer.ThreadingUDPServer((bind_addr, self.port),\
self.serverClass),
]
routines = [
threading.Thread(name='CacheManager', target=self.cache_manager,\
args=())
]
for s in servers:
thread = threading.Thread(target=s.serve_forever)
# that thread will start one more thread for each request
thread.daemon = True
# exit the server thread when the main thread terminates
thread.start()
logging.info("%s server loop running in thread: %s",\
s.RequestHandlerClass.__name__[:3], thread.name)
for r in routines:
r.daemon = True
r.start()
logging.info("Routine %s started", r.name)
try:
while 1:
time.sleep(1)
sys.stderr.flush()
sys.stdout.flush()
except KeyboardInterrupt:
pass
finally:
logging.warning('Shutting down servers')
for s in servers:
s.shutdown()
def start_server(self):
parser = argparse.ArgumentParser(\
formatter_class=argparse.ArgumentDefaultsHelpFormatter,\
description='very fast DNS resolver')
parser.add_argument('-p', '--port', type=int, default=53,\
help='the TCP port number the agent listens')
parser.add_argument('-d', '--daemon', action='store_true',\
default=False, help='run the agent as a daemon')
parser.add_argument('-l', '--loopback', action='store_true',\
default=False, help='bind to 127.0.0.1.')
parser.add_argument('-k', '--kill', action='store_true',\
default=False, help='kill a running daemon')
parser.add_argument('-q', '--quiet', action='store_true',\
default=False, help='only print errors')
parser.add_argument('-v', '--verbose', action='store_true',\
default=False, help='print debug info.')
args = parser.parse_args()
if args.quiet:
level = logging.WARNING
elif args.verbose:
level = logging.DEBUG
else:
level = logging.INFO
logging.basicConfig(
format="%(levelname) -10s %(asctime)s\
%(threadName)s:%(lineno) -7s %(message)s",
level=level
)
self.port = args.port
bind_addr = '0.0.0.0'
if args.loopback:
bind_addr = '127.0.0.1'
if args.daemon:
pidFile = daemon.pidfile.PIDLockFile(PIDFILE)
pid = pidFile.read_pid()
if pid is not None:
logging.critical("Another daemon, PID %d, is running. Quit.",\
pid)
sys.exit(-1)
serverLog = open('DNSserver.log', 'a+')
context = daemon.DaemonContext(stdout=serverLog,\
stderr=serverLog,\
pidfile=pidFile)
context.files_preserve = [serverLog]
with context:
logging.info("Starting Daemon on port %d", args.port)
self.do_start_server(bind_addr)
elif args.kill:
pidFile = daemon.pidfile.PIDLockFile(PIDFILE)
pid = pidFile.read_pid()
if pid is None:
logging.error("No daemon found.")
sys.exit(-1)
else:
os.kill(int(pid), signal.SIGINT)
logging.info("PID %d killed", pid)
else:
self.do_start_server(bind_addr)
if __name__ == '__main__':
dns_server = DNSserver(port=53, serverClass=DNSUDPRequestHandler)
dns_server.start_server()