def handle_response(self, packet, sender):
"""Handle DNS response from upstream server."""
if packet['qdcount'] == 0:
logging.warn('Bad response from upstream server: %s',
pprint.pformat(packet))
return
# Find original query
query_id_o = packet['id']
query_o = self.find_query(sender[0], sender[1], query_id_o)
if query_o and packet['qdcount'] > 0:
qname = packet['questions'][0][0]
qtype = packet['questions'][0][1]
send_reply = True
query_again = False
hit_found = False
packet_o = query_o[0]
# Replace with the original query id
packet['id'] = packet_o['id']
if qtype == DNS.Type.HIP and query_o[3] in (DNS.Type.A,
DNS.Type.AAAA):
# Restore qtype
packet['questions'][0][1] = query_o[3]
self.hip_lookup(packet)
if packet['ancount'] > 0:
hit_found = True
if (not self.prefix or
(hit_found
and not (self.getaaaa(qname) or self.geta(qname)))):
query_again = True
send_reply = False
elif self.prefix:
hit_found = True
packet['questions'][0][0] = (self.prefix +
packet['questions'][0][0])
for answer in packet['answers']:
answer[0] = self.prefix + answer[0]
elif qtype in (DNS.Type.A, DNS.Type.AAAA):
hit = self.getaaaa_hit(qname)
ip6 = self.getaaaa(qname)
ip4 = self.geta(qname)
for answer in packet['answers']:
if answer[1] in (DNS.Type.A, DNS.Type.AAAA):
self.cache_name(qname, answer[4], answer[3])
if hit is not None:
for answer in packet['answers']:
if (answer[1] == DNS.Type.A
or (answer[1] == DNS.Type.AAAA
and not hosts.valid_hit(answer[4]))):
add_hit_ip_map(hit[0], answer[4])
# Reply with HIT/LSI once it's been mapped
# to an IP
if ip6 is None and ip4 is None:
if (packet_o['ancount'] == 0 and not self.prefix):
# No LSI available. Return IPv4
tmp = packet['answers']
packet = packet_o
packet['answers'] = tmp
packet['ancount'] = len(packet['answers'])
else:
packet = packet_o
if self.prefix:
packet['questions'][0][0] = (
self.prefix + packet['questions'][0][0])
for answer in packet['answers']:
answer[0] = (self.prefix + answer[0])
else:
send_reply = False
elif query_o[3] == 0:
# Prefix is in use
# IP was queried for cache only
send_reply = False
elif qtype == DNS.Type.PTR and isinstance(query_o[3], str):
packet['questions'][0][0] = query_o[3]
for answer in packet['answers']:
answer[0] = query_o[3]
if query_again:
if hit_found:
qtypes = [DNS.Type.AAAA, DNS.Type.A]
pckt = copy.deepcopy(packet)
else:
qtypes = [query_o[3]]
pckt = copy.copy(packet)
pckt['qr'] = 0
pckt['answers'] = []
pckt['ancount'] = 0
pckt['nslist'] = []
pckt['nscount'] = 0
pckt['additional'] = []
pckt['arcount'] = 0
for qtype in qtypes:
if self.prefix:
query = (packet, query_o[1], query_o[2], 0)
else:
query = (packet, query_o[1], query_o[2], qtype)
self.query_id = (self.query_id % 65535) + 1
pckt['id'] = self.query_id
pckt['questions'][0][1] = qtype
outbuf = DNS.Serialize(pckt).get_packet()
self.clisock.sendto(outbuf,
(self.server_ip, self.server_port))
self.add_query(self.server_ip, self.server_port,
self.query_id, query)
packet['questions'][0][1] = query_o[3]
if send_reply:
outbuf = DNS.Serialize(packet).get_packet()
self.servsock.sendto(outbuf, (query_o[1], query_o[2]))
def handle_query(self, packet, sender):
"""Handle DNS query from downstream client."""
qtype = packet['questions'][0][1]
sent_answer = False
if qtype in (DNS.Type.A, DNS.Type.AAAA, DNS.Type.PTR):
if self.hip_cache_lookup(packet):
try:
outbuf = DNS.Serialize(packet).get_packet()
self.servsock.sendto(outbuf, sender)
sent_answer = True
except socket.error:
logging.exception('Exception:')
elif (self.prefix
and packet['questions'][0][0].startswith(self.prefix)):
# Query with HIP prefix for unsupported RR type.
# Send empty response.
packet['qr'] = 1
try:
outbuf = DNS.Serialize(packet).get_packet()
self.servsock.sendto(outbuf, sender)
sent_answer = True
except socket.error:
logging.exception('Exception:')
if self.connected and not sent_answer:
logging.info('Query type %d for %s from %s', qtype,
packet['questions'][0][0],
(self.server_ip, self.server_port))
query = (packet, sender[0], sender[1], qtype)
# FIXME: Should randomize for security
self.query_id = (self.query_id % 65535) + 1
pckt = copy.copy(packet)
pckt['id'] = self.query_id
if ((qtype == DNS.Type.AAAA or
(qtype == DNS.Type.A and not self.disable_lsi))
and not is_reverse_hit_query(packet['questions'][0][0])):
if not self.prefix:
pckt['questions'][0][1] = DNS.Type.HIP
if (self.prefix
and pckt['questions'][0][0].startswith(self.prefix)):
pckt['questions'][0][0] = pckt['questions'][0][0][
len(self.prefix):]
pckt['questions'][0][1] = DNS.Type.HIP
if qtype == DNS.Type.PTR and not self.disable_lsi:
qname = packet['questions'][0][0]
addr_str = hosts.ptr_to_addr(qname)
if (addr_str is not None and hosts.valid_lsi(addr_str)):
query = (packet, sender[0], sender[1], qname)
hit_str = lsi_to_hit(addr_str)
if hit_str is not None:
pckt['questions'][0][0] = hosts.addr_to_ptr(hit_str)
outbuf = DNS.Serialize(pckt).get_packet()
self.clisock.sendto(outbuf, (self.server_ip, self.server_port))
self.add_query(self.server_ip, self.server_port, self.query_id,
query)
