--- /dev/null
+#!/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()
+