def _make_txt(self, packet: Packet) -> Packet:
try:
subdomain, *domains = packet.subdomain_from_qname.split(".")
domains = domains[::-1]
data = Domain.decode(subdomain)
except binascii.Error:
# couldn't decode, drop the packet and do nothing
logger.debug("Couldn't decode subdomain in %s", packet.qname)
return
return Packet.build_reply(
{
"src": self.host_ip,
"dst": packet.src,
"dport": packet.sport,
"dns": {
"id":
packet.id,
"question":
packet.question,
"messages": [
self._make_message(
packet.qname,
self.on_query(data, packet.src, domains)),
],
},
},
self.domain,
)
def _make_a(self, packet: Packet) -> Packet:
if self.config is None:
return
# if we receive a DNS A query for a subdomain, answer it with an ip from
# the configuration file
qname = packet.qname[:-1] # remove final '.'
if qname in self.config.sections():
return Packet.build_reply(
{
"src": self.host_ip,
"dst": packet.src,
"dport": packet.sport,
"dns": {
"id":
packet.id,
"question":
packet.question,
"messages": [
DNSRR(
rrname=packet.qname,
rdata=self.config[qname]["ip"],
type=DNSAnswer.Type.HostAddr,
ttl=int(self.config[qname]["ttl"]),
),
],
},
},
self.domain,
)
def dns_responder(self, pkt: IP):
packet = Packet(pkt, self.domain)
if packet.is_valid_dnsquery():
self.logger.info("got a packet from %s:%i", packet.src,
packet.sport)
subdomain = packet.subdomain_from_qname.split('.')[0]
self.logger.debug("subdomain: %s", subdomain)
try:
data = Domain.decode(subdomain)
except binascii.Error:
# couldn't decode, drop the packet and do nothing
return
# keep destination
answer = Packet.build_reply(
{
"src": self.host_ip,
"dst": packet.src,
"dport": packet.sport,
"dns": {
"id":
packet.id,
"question":
packet.question,
# TODO ensure that we're under the 500 bytes limit
"messages": [
DNSRR(
rrname=packet.qname,
rdata=Content.encode(
self.on_query(data, packet.src)),
type=DNSAnswer.Type.Text,
ttl=60, # a minute long
),
],
},
},
self.domain,
)
self.logger.debug("Answering %s", answer.dns.summary())
send(answer.packet, verbose=0, iface=self.interface)
def dns_responder(self, pkt: IP):
packet = Packet(pkt, self.domain)
if packet.is_valid_dnsquery():
subdomain = packet.subdomain_from_qname
logging.debug("subdomain: %s", subdomain)
data = Domain.decode(subdomain)
logging.debug("decoded: %s", data)
# keep destination
logging.debug("packet from %s:%i", packet.src, packet.sport)
answer = Packet.build_reply(
{
"src": self.host_ip,
"dst": packet.src,
"dport": packet.sport,
"dns": {
"id":
packet.id,
# TODO ensure that we're under the 500 bytes limit
"messages": [
DNSRR(
rrname=packet.qname,
rdata=Content.encode("test"),
type=DNSAnswer.Type.Text,
),
],
},
},
self.domain,
)
logging.debug("incomming packet type: %s",
hex(packet.question.qtype))
logging.debug(answer.dns.summary())
send(answer.packet, verbose=2, iface=self.interface)
