208 lines
6.3 KiB
Python
Executable File
208 lines
6.3 KiB
Python
Executable File
#!/usr/bin/python
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# -*- coding: utf-8 -*-
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#
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# Copyright 2017 René Moser <mail@renemoser.net>
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import sys
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import re
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import os
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import ConfigParser
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DEBUG = 0
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def log(msg):
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sys.stderr.write('backend (%s): %s\n' % (os.getpid(), msg))
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def write(*l):
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args = len(l)
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c = 0
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for a in l:
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c += 1
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if DEBUG:
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log('writing: %s' % a)
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sys.stdout.write(a)
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if c < args:
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if DEBUG:
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log('writetab')
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sys.stdout.write('\t')
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if DEBUG:
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log('writenewline')
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sys.stdout.write('\n')
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sys.stdout.flush()
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def get_next():
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if DEBUG:
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log('reading now')
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l = sys.stdin.readline()
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if DEBUG:
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log('read line: %s' % l)
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return l.strip().split('\t')
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class DynamicBackend:
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def __init__(self):
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self.id = ''
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self.soa = ''
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self.domain = ''
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self.ip_address = ''
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self.ttl = ''
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self.name_servers = {}
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self.additional_cnames = {}
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def configure(self):
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fname = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'backend.conf')
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if not os.path.exists(fname):
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log('%s does not exist' % fname)
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sys.exit(1)
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fp = open(fname)
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config = ConfigParser.ConfigParser()
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config.readfp(fp)
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fp.close()
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self.id = config.get('soa', 'id')
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self.soa = '%s %s %s' % (config.get('soa', 'ns'), config.get('soa', 'hostmaster'), self.id)
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self.domain = config.get('main', 'domain')
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self.ip_address = config.get('main', 'ipaddress')
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self.ttl = config.get('main', 'ttl')
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for entry in config.items('nameservers'):
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if not entry[0].endswith(self.domain):
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name = entry[0] + '.' + self.domain
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else:
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name = entry[0]
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self.name_servers[name] = entry[1]
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for entry in config.items('additional_cnames') or []:
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if not entry[0].endswith(self.domain):
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name = entry[0] + '.' + self.domain
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else:
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name = entry[0]
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self.additional_cnames[name] = entry[1]
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log('add static CNAME: %s = %s' % (entry[0], entry[1]))
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log('Name servers: %s' % self.name_servers)
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log('ID: %s' % self.id)
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log('TTL %s' % self.ttl)
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log('SOA: %s' % self.soa)
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log('IP Address: %s' % self.ip_address)
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log('DOMAIN: %s' % self.domain)
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def run(self):
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log('starting up')
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handshake = get_next()
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if handshake[1] != '1':
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log('Not version 1: %s' % handshake)
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sys.exit(1)
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write('OK', 'We are good')
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log('Done handshake')
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while True:
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cmd = get_next()
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if DEBUG:
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log(cmd)
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if len(cmd) < 6:
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log('did not understand: %s' % cmd)
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write('FAIL')
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continue
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qname = cmd[1].lower()
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qtype = cmd[3]
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if qtype in ('CNAME', 'A', 'ANY') and qname.endswith(self.domain):
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if qname == self.domain:
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self.handle_self(self.domain)
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elif qname in self.name_servers:
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self.handle_nameservers(qname)
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elif qname in self.additional_cnames:
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self.handle_additional_cnames(qname)
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else:
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self.handle_subdomains(qname)
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elif qtype == 'SOA' and qname.endswith(self.domain):
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self.handle_soa(qname)
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else:
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self.handle_unknown(qtype, qname)
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def handle_self(self, name):
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write('DATA', name, 'IN', 'A', self.ttl, self.id, self.ip_address)
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self.write_name_servers(name)
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write('END')
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def handle_subdomains(self, qname):
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subdomain = qname[0:qname.find(self.domain) - 1]
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match = re.findall('^(?:.+[-.])?(\d{1,3}[-.]\d{1,3}[-.]\d{1,3}[-.]\d{1,3})$', subdomain)
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if not match:
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if DEBUG:
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log('%s is invalid format' % subdomain)
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self.handle_self(qname)
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return
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ipaddress = re.split('[-.]', match[0])
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if DEBUG:
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log('ip: %s' % ipaddress)
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for part in ipaddress:
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if re.match('^\d{1,3}$', part) is None:
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if DEBUG:
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log('%s is not a number' % part)
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self.handle_self(qname)
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return
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parti = int(part)
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if parti < 0 or parti > 255:
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if DEBUG:
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log('%d is too big/small' % parti)
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self.handle_self(qname)
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return
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write('DATA', qname, 'IN', 'A', self.ttl, self.id, '%s.%s.%s.%s' % (ipaddress[0], ipaddress[1], ipaddress[2], ipaddress[3]))
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self.write_name_servers(qname)
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write('END')
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def handle_additional_cnames(self, qname):
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if DEBUG:
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log('Found CNAME: %s' % qname)
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cname=self.additional_cnames[qname]
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write('DATA', qname, 'IN', 'CNAME', self.ttl, self.id, cname)
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write('END')
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def handle_nameservers(self, qname):
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if DEBUG:
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log('Found name server: %s' % qname)
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ip = self.name_servers[qname]
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write('DATA', qname, 'IN', 'A', self.ttl, self.id, ip)
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write('END')
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def write_name_servers(self, qname):
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for nameServer in self.name_servers:
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write('DATA', qname, 'IN', 'NS', self.ttl, self.id, nameServer)
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def handle_soa(self, qname):
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write('DATA', qname, 'IN', 'SOA', self.ttl, self.id, self.soa)
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write('END')
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def handle_unknown(self, qtype, qname):
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write('LOG', 'Unknown type: %s, domain: %s' % (qtype, qname))
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write('END')
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if __name__ == '__main__':
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backend = DynamicBackend()
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backend.configure()
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backend.run()
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