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README.md

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+Python, DNS and Redis
+
+Simple servers to deliver customized DNS data. These servers rely on Redis as storage backend.
+
+Both of them rely on google's dns as fallback
+
+gevent version
+==============
+gevent_dns.py
+
+to create a new domain:
+    set IP:name ip_addr
+    set TXT:name txtfield
+
+twisted version
+===============
+tx_dns.py
+
+create a new domain SET: 
+    domain.tld ip_addr

gevent_dns.py

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+# dns server using dnslib and gevent
+# based on https://bitbucket.org/paulc/dnslib/src/80d85555aae4/src/server/gevent_server.py
+# set the key as
+# set IP:name ip_addr
+# set TXT:name txtfield
+# fallback on gevent's dns resolver
+# gleicon 2011
+
+
+import gevent
+from gevent import socket
+import gevent.dns;
+from gevent import monkey;
+monkey.patch_socket()
+
+import urllib2,sys
+import redis
+import random
+from dnslib import *
+
+
+AF_INET = 2
+SOCK_DGRAM = 2
+
+s = socket.socket(AF_INET,SOCK_DGRAM)
+s.bind(('',53))
+
+def dns_handler(s, peer, data, r):
+    request = DNSRecord.parse(data)
+    id = request.header.id
+    qname = request.q.qname
+    qtype = request.q.qtype
+    IP = r.get("IP:%s" % qname)
+    TXT = r.get("TXT:%s" % qname)
+    if not IP:
+        try:
+            IP = socket.gethostbyname(str(qname))
+        except Exception, e:
+            print 'Host not found'
+            IP = '0.0.0.0'
+    print "Request (%s): %r (%s) - Response: %s" % (str(peer), qname.label, QTYPE[qtype], IP)
+    reply = DNSRecord(DNSHeader(id=id,qr=1,aa=1,ra=1),q=request.q)
+    if qtype == QTYPE.A:
+        reply.add_answer(RR(qname,qtype,rdata=A(IP)))
+    elif qtype == QTYPE['*']:
+        reply.add_answer(RR(qname,QTYPE.A,rdata=A(IP)))
+        reply.add_answer(RR(qname,QTYPE.MX,rdata=MX(IP)))
+        reply.add_answer(RR(qname,QTYPE.TXT,rdata=TXT(TXT)))
+    else:
+        reply.add_answer(RR(qname,QTYPE.CNAME,rdata=CNAME(TXT)))
+    s.sendto(reply.pack(),peer)
+
+
+def main():
+    r = redis.Redis()
+    while True:
+        data,peer = s.recvfrom(8192)
+        gevent.spawn(dns_handler, s, peer, data, r)
+
+if __name__ == '__main__':
+    main()

tx_dns.py

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+# Python/Twisted/Redis backed DNS server - resolves from NAME to IP addrs
+# fallback to google or any other DNS server to resolv domains not present on Redis
+# to set a new domain on redis, just issue a SET domain.tld ip_addr
+# run with twistd -ny txredns.tac
+# gleicon 2011
+
+from twisted.names import dns, server, client, cache
+from twisted.application import service, internet
+from twisted.internet import defer
+from twisted.python import log
+import txredisapi
+
+class RedisResolverBackend(client.Resolver):
+    def __init__(self, redis, servers=None):
+        self.redis = redis
+        client.Resolver.__init__(self, servers=servers)
+        self.ttl = 5
+
+    @defer.inlineCallbacks
+    def _get_ip_addr(self, hostname, timeout):
+        ip = yield self.redis.get(hostname)
+        r = None
+        if ip:
+            defer.returnValue([(dns.RRHeader(hostname, dns.A, dns.IN, self.ttl, dns.Record_A(ip, self.ttl)),), (), ()])
+        else:
+            i = yield self._lookup(hostname, dns.IN, dns.A, timeout)
+            defer.returnValue(i)
+
+    def lookupAddress(self, name, timeout = None):
+        return self._get_ip_addr(name, timeout)
+
+def create_application():
+    rd = txredisapi.lazyRedisConnectionPool()
+    redisBackend = RedisResolverBackend(rd, servers=[('8.8.8.8', 53)])
+
+    application = service.Application("txdnsredis")
+    srv_collection = service.IServiceCollection(application)
+
+    dnsFactory = server.DNSServerFactory(caches=[cache.CacheResolver()], clients=[redisBackend])
+
+    internet.TCPServer(53, dnsFactory).setServiceParent(srv_collection)
+    internet.UDPServer(53, dns.DNSDatagramProtocol(dnsFactory)).setServiceParent(srv_collection)
+    return application
+
+# .tac app
+application = create_application()
+
+