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#!/usr/bin/python
import sys
import re
import os
import ConfigParser
DEBUG=0
def log(msg):
sys.stderr.write('backend: %s\n' % msg)
def write(*l):
args=len(l)
c = 0
for a in l:
c += 1
if DEBUG: log('writing: %s' % a)
sys.stdout.write(a)
if c < args:
if DEBUG: log('writetab')
sys.stdout.write('\t')
if DEBUG: log('writenewline')
sys.stdout.write('\n')
sys.stdout.flush()
def get_next():
if DEBUG: log('reading now')
l = sys.stdin.readline()
if DEBUG: log('read line: %s' % l)
return l.strip().split('\t')
class DynamicBackend:
def __init__(self):
self.id = ''
self.soa = ''
self.domain = ''
self.ip_address = ''
self.ttl = ''
self.name_servers = {}
def configure(self):
fname = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'backend.conf')
if not os.path.exists(fname):
log('%s does not exist' % fname)
sys.exit(1)
fp = open(fname)
config = ConfigParser.ConfigParser()
config.readfp(fp)
fp.close()
self.id = config.get('soa', 'id')
self.soa = '%s %s %s' % (config.get('soa', 'ns'), config.get('soa','hostmaster'), self.id)
self.domain = config.get('main', 'domain')
self.ip_address = config.get('main', 'ipaddress')
self.ttl = config.get('main', 'ttl')
for entry in config.items('nameservers'):
self.name_servers[entry[0]] = entry[1]
log('Name servers: %s' % self.name_servers)
log('ID: %s' % self.id)
log('TTL %s' % self.ttl)
log('SOA: %s' % self.soa)
log('IP Address: %s' % self.ip_address)
log('DOMAIN: %s' % self.domain)
def run(self):
log('starting up')
handshake = get_next()
if handshake[1] != '1':
log('Not version 1: %s' % handshake)
sys.exit(1)
write('OK', 'We are good')
log('Done handshake')
while True:
cmd = get_next()
if DEBUG: log(cmd)
if len(cmd) < 6:
log('did not understand: %s' % cmd)
write('FAIL')
continue
qname = cmd[1]
qtype = cmd[3]
if (qtype == 'A' or qtype == 'ANY') and qname.endswith(self.domain):
if qname == self.domain:
self.handle_self(self.domain)
elif qname in self.name_servers:
self.handle_nameservers(qname)
else:
self.handle_subdomains(qname)
elif qtype == 'SOA':
self.handle_soa(qname)
else:
self.handle_unknown(qtype, qname)
def handle_self(self, name):
write('DATA', name, 'IN', 'A', self.ttl, self.id, self.ip_address)
self.write_name_servers(name)
write('END')
def handle_subdomains(self, qname):
subdomain = qname[0:qname.find(self.domain)-1]
subparts = subdomain.split('.')
if len(subparts) < 4:
if DEBUG: log('subparts less than 4')
self.handle_self(qname)
return
ipaddress = subparts[-4:]
if DEBUG: log('ip: %s' % ipaddress)
for part in ipaddress:
if re.match('^\d{1,3}$', part) is None:
if DEBUG: log('%s is not a number' % part)
self.handle_self(qname)
return
parti = int(part)
if parti < 0 or parti > 255:
if DEBUG: log('%d is too big/small' % parti)
self.handle_self(qname)
return
write('DATA', qname, 'IN', 'A', self.ttl, self.id, '%s.%s.%s.%s' % (ipaddress[0], ipaddress[1], ipaddress[2], ipaddress[3]))
self.write_name_servers(qname)
write('END')
def handle_nameservers(self, qname):
ip = self.name_servers[qname]
write('DATA', qname, 'IN', 'A', self.ttl, self.id, ip)
write('END')
def write_name_servers(self, qname):
for nameServer in self.name_servers:
write('DATA', qname, 'IN', 'NS', self.ttl, self.id, nameServer)
def handle_soa(self, qname):
write('DATA', qname, 'IN', 'SOA', self.ttl, self.id, self.soa)
write('END')
def handle_unknown(self, qtype, qname):
write('LOG', 'Unknown type: %s, domain: %s' % (qtype, qname))
write('FAIL')
if __name__ == '__main__':
backend = DynamicBackend()
backend.configure()
backend.run()
|
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