def test_header_from_bytes(self):
packet = b"\x00\x01\x00\x02\x00\x03\x00\x04\x00\x05\x00\x06"
header = Header(1, 2, 3, 4, 5, 6)
self.assertEqual(Header.from_bytes(packet), header)
def test_qr(self):
header = Header(0, 0, 0, 0, 0, 0)
header.qr = 1
self.assertEqual(header.qr, 1)
def test_flags_rcode(self):
header = Header(0, 0, 0, 0, 0, 0)
header.rcode = 15
self.assertEqual(header.flags, 15)
def test_header_to_bytes(self):
header = Header(1, 2, 3, 4, 5, 6)
self.assertEqual(header.to_bytes(),
b"\x00\x01\x00\x02\x00\x03\x00\x04\x00\x05\x00\x06")
def handle_request(self):
""" Attempts to answer the received query """
#Check this next to the given algorithm
#print("Catalog:",self.catalog.zones)
#for zone in self.catalog.zones:
# print("Records:",self.catalog.zones[zone].records)
if self.message.header.opcode != 0: #Send a not implemented error, we don't need to support those kinds of queries
print("[-] - Received a nonstandard query. This is unsupported.")
header = Header(ident, 0, 1, 0, 0, 0)
header.qr = 1
header.rd = self.message.header.rd
header.ra = 1
header.rcode = 4
self.sendResponse(Message(header, self.message.questions, []))
return
#print("[*] - Handling request.")
if len(self.message.questions) != 1: #Send a format error response
print("[-] - Invalid request.")
header = Header(ident, 0, 1, 0, 0, 0)
header.qr = 1
header.rd = self.message.header.rd
header.ra = 1
header.rcode = 1
self.sendResponse(Message(header, self.message.questions, []))
return
#print("MSG:",self.message)
#print("RECEIVED QUESTION",self.message.questions[0])
hname = str(self.message.questions[0].qname)
#print("Solving",hname,type(hname))
ident = self.message.header.ident
#print("Checking zone")
answer, authority, found = self.check_zone(hname)
#print("Wat we in de zone hebben gevonden")
#print("ANS:",answer,"AUTH:",authority,"FOUND:",found)
#found = False
if found:
print("Found in zone")
header = Header(ident, 0, 1, len(answer), len(authority), 0)
header.qr = 1
header.aa = 1
header.rd = self.message.header.rd
header.ra = 1
self.sendResponse(
Message(header, self.message.questions, answer, authority))
elif self.message.header.rd == 1:
h, al, ad = self.resolver.gethostbyname(hname)
#Make and send th appropriate response
header = Header(ident, 0, 1, len(al) + len(ad), 0, 0)
header.qr = 1
header.rd = self.message.header.rd
header.ra = 1
aliases = [
ResourceRecord(Name(h), Type.CNAME, Class.IN, self.ttl,
RecordData.create(Type.CNAME, Name(alias)))
for alias in al
]
addresses = [
ResourceRecord(Name(h), Type.A, Class.IN, self.ttl,
RecordData.create(Type.A, address))
for address in ad
]
self.sendResponse(
Message(header, self.message.questions, aliases + addresses))
else: #Send an empty response
header = Header(ident, 0, 1, 0, 0, 0)
header.qr = 1
header.rd = self.message.header.rd
header.ra = 1
header.rcode = 0
self.sendResponse(Message(header, self.message.questions, []))
def test_flags_ra(self):
header = Header(0, 0, 0, 0, 0, 0)
header.ra = 1
self.assertEqual(header.flags, 1 << 7)
def test_rd(self):
header = Header(0, 0, 0, 0, 0, 0)
header.rd = 1
self.assertEqual(header.rd, 1)
def test_flags_opcode(self):
header = Header(0, 0, 0, 0, 0, 0)
header.opcode = 15
self.assertEqual(header.flags, 15 << 11)
def test_tc(self):
header = Header(0, 0, 0, 0, 0, 0)
header.tc = 1
self.assertEqual(header.tc, 1)
def test_flags_tc(self):
header = Header(0, 0, 0, 0, 0, 0)
header.tc = 1
self.assertEqual(header.flags, 1 << 9)
def test_flags_aa(self):
header = Header(0, 0, 0, 0, 0, 0)
header.aa = 1
self.assertEqual(header.flags, 1 << 10)
def gethostbyname(self, hostname, dnsserv='192.112.36.4'):
"""Translate a host name to IPv4 address.
Currently this method contains an example. You will have to replace
this example with the algorithm described in section 5.3.3 in RFC 1034.
Args:
hostname (str): the hostname to resolve
Returns:
(str, [str], [str]): (hostname, aliaslist, ipaddrlist)
"""
ipaddrlist = []
cnames = []
temp = []
if (self.caching):
rcache = RecordCache(self.ttl)
rcord = rcache.lookup(hostname, Type.ANY, Class.IN)
if (rcord):
for rec in rcord:
if rec.type_ == Type.A:
arec = rec.rdata
ipaddrlist.append(arec.address)
elif rec.type_ == Type.CNAME:
crec = rec.rdata
cnames.append(crec.cname)
if ipaddrlist:
return hostname, cnames, ipaddrlist
elif cnames:
return self.gethostbyname(cnames[0], dnsserv)
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.settimeout(self.timeout)
# Create and send query
question = Question(Name(str(hostname)), Type.A, Class.IN)
header = Header(9001, 0, 1, 0, 0, 0)
header.qr = 0
header.opcode = 0
header.rd = 1
query = Message(header, [question])
sock.sendto(query.to_bytes(), (str(dnsserv), 53))
# Receive response
data = sock.recv(2048)
response = Message.from_bytes(data)
print("Number of answers: " + str(len(response.answers)))
print("Number of authorities: " + str(len(response.authorities)))
print("Number of additionals: " + str(len(response.additionals)))
# Get data
aliaslist = cnames
ipaddrlist = []
dnslist = []
while response.answers:
for answer in response.answers:
if answer.type_ == Type.A:
print("found A RR")
if (self.caching):
rcache.add_record(answer)
ipaddrlist.append(answer.rdata.address)
if answer.type_ == Type.CNAME:
aliaslist.append(answer.rdata.cname)
if answer.type_ == Type.NS:
dnslist.append(answer.rdata.nsdname)
if ipaddrlist:
return hostname, aliaslist, ipaddrlist
elif aliaslist:
question = Question(Name(aliaslist[0]), Type.A, Class.IN)
query = Message(header, [question])
sock.sendto(query.to_bytes(), (dnsserv, 53))
data = sock.recv(2048)
response = Message.from_bytes(data)
elif dnslist:
nsname = dnslist.pop()
maybe_dnsserv = self.getnsaddr(nsname, response.additionals)
if maybe_dnsserv:
dnsserv = maybe_dnsserv
else:
pass
sock.sendto(query.to_bytes(), (dnsserv, 53))
data = sock.recv(2048)
response = Message.from_bytes(data)
else:
break
if response.authorities:
for authority in response.authorities:
if authority.type_ != Type.NS:
pass
dnslist.append(authority.rdata.nsdname)
while dnslist:
nsname = dnslist.pop()
maybe_next_dnsserv = self.getnsaddr(nsname,
response.additionals)
if maybe_next_dnsserv:
next_dns_serv = maybe_next_dnsserv
else:
pass
(hname, aliasl, ipaddrl) = self.gethostbyname(hostname, nsname)
if ipaddrl:
return hname, aliasl, ipaddrl
def gethostbyname(self, hostname):
"""Translate a host name to IPv4 address.
Currently this method contains an example. You will have to replace
this example with the algorithm described in section 5.3.3 in RFC 1034.
Args:
hostname (str): the hostname to resolve
Returns:
(str, [str], [str]): (hostname, aliaslist, ipaddrlist)
"""
alias_list = []
a_list = []
slist = []
found = False
acs = self.getRecordsFromCache(hostname, Type.A, Class.IN)
if acs:
a_list += acs
return hostname, alias_list, a_list
nscs = self.matchByLabel(hostname, Type.NS, Class.IN)
for ns in nscs:
glue = self.getRecordsFromCache(str(ns.rdata.nsdname))
if glue:
slist += glue
else:
slist += [ns]
id = self._make_id()
# Create and send query
question = Question(Name(hostname), Type.A, Class.IN)
header = Header(id, 0, 1, 0, 0, 0)
header.qr = 0 # 0 for query
header.opcode = 0 # standad query
header.rd = 0 # not recursive
query = Message(header, [question])
self.zone.read_master_file('dns/root.zone')
sbelt = []
for root in list(self.zone.records.values()):
sbelt += [r for r in root if r.type_ == Type.A]
while not found:
if slist:
rr = slist.pop()
if rr.type_ == Type.A:
addr = rr.rdata.address
self.sock.send((query, addr, 53))
elif rr.type_ == Type.NS:
fqdn = str(rr.rdata.nsdname)
_, _, a_rrs = self.gethostbyname(fqdn)
slist += a_rrs
continue
elif rr.type_ == Type.CNAME:
fqdn = str(rr.rdata.cname)
_, cname_rrs, a_rrs = self.gethostbyname(fqdn)
a_list += a_rrs
alias_list += cname_rrs
break
elif sbelt:
rr = sbelt.pop()
addr = rr.rdata.address
self.sock.send((query, addr, 53))
else:
break
# Receive response
data = None
while not data:
data = self.sock.msgThere(id)
response, _ = data[0]
#response = Message.from_bytes(data)
for answer in response.answers:
if answer.type_ == Type.A:
self.addRecordToCache(answer)
a_list.append(answer)
found = True
if answer.type_ == Type.CNAME:
self.addRecordToCache(answer)
alias_list.append(answer)
slist += [answer]
continue
nss = []
for auth in response.authorities:
if auth.type_ == Type.NS:
nss.append(auth)
self.addRecordToCache(auth)
a_add = {}
for add in response.additionals:
if add.type_ == Type.A:
name = str(add.name)
a_add[name] = add
self.addRecordToCache(add)
for ns in nss:
name = str(ns.rdata.nsdname)
if name in a_add:
slist += [a_add[name]]
else:
slist += [ns]
return hostname, alias_list, a_list
def test_flags_qr(self):
header = Header(0, 0, 0, 0, 0, 0)
header.qr = 1
self.assertEqual(header.flags, 1 << 15)
def test_flags_rd(self):
header = Header(0, 0, 0, 0, 0, 0)
header.rd = 1
self.assertEqual(header.flags, 1 << 8)
def test_opcode(self):
header = Header(0, 0, 0, 0, 0, 0)
header.opcode = 1
self.assertEqual(header.opcode, 1)
def test_ra(self):
header = Header(0, 0, 0, 0, 0, 0)
header.ra = 1
self.assertEqual(header.ra, 1)
def test_aa(self):
header = Header(0, 0, 0, 0, 0, 0)
header.aa = 1
self.assertEqual(header.aa, 1)
def run(self):
""" Run the handler thread"""
msg = Message.from_bytes(self.data)
header = msg.header
recursion = header.rd != 0
questions = msg.questions
answers = []
authorative = []
additional = []
for question in questions:
qname = question.qname
qtype = question.qtype
if question.qclass != Class.IN:
pass
domains = self.getdomains(str(qname))
for domain in domains:
if not self.zone.records.get(domain, False):
continue
for rr in self.zone.records[domain]:
if (rr.type_ == Type.A or rr.type_
== Type.CNAME) and domain == str(qname):
answers.append(rr)
if rr.type_ == Type.NS:
authorative.append(rr)
for rec in self.zone.records[str(rr.rdata.nsdname)]:
if rec not in additional:
if rec.qtype == Type.A:
additional.append(rec)
if authorative or answers:
header_response = Header(9001, 0, 1, len(answers),
len(authorative), len(additionals))
header_response.qr = True
header_response.opcode(1)
header_response.aa(False)
header_respones.tc(False)
header_response.rd(False)
header_response.ra(True)
header_response.z(False)
header_respones.rcode(False)
respons = Message(header_response, [question], answers,
authorities, additionals)
self.sock.sendto(respons.to_bytes(), self.addr)
break
if recursion and (qtype == Type.A or qtype == Type.CNAME):
answers = []
resolver = Resolver(100, False, 0, True)
(hostname, aliaslist,
ipaddrlist) = resolver.gethostbyname(question.qname)
header_response = Header(9001, 0, 1,
len(aliaslist) + len(ipaddrlist), 0,
0)
header_response.qr = 1
header_response.opcode = 1
header_response.aa = 0
header_response.tc = 0
header_response.rd = 0
header_response.ra = 1
header_response.rcode = 0
for addr in ipaddrlist:
answers.append(
ResourceRecord.from_dict({
"name": str(hostname),
"type": str(Type.A),
"class": str(Class.IN),
"ttl": 0,
"rdata": {
"address": str(addr)
}
}))
for alias in aliaslist:
answers.append(
ResourceRecord.from_dict({
"name": str(hostname),
"type": str(Type.CNAME),
"class": str(Class.IN),
"ttl": 0,
"rdata": {
"cname": str(alias)
}
}))
response = Message(header_response, questions, answers)
self.sock.sendto(response.to_bytes(), self.addr)
break
