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#!/usr/bin/env python3
import dns.edns
import dns.message
import dns.query
import dns.resolver
n = "."
t = dns.rdatatype.SOA
l = "199.7.83.42" # Address of l.root-servers.net
i = "149.20.1.73" # Address of ns1.isc.org, for COOKIEs
q_list = []
# A query without EDNS0
q_list.append((l, dns.message.make_query(n, t)))
# The same query, but with EDNS0 turned on with no options
q_list.append((l, dns.message.make_query(n, t, use_edns=0)))
# Use use_edns() to specify EDNS0 options, such as buffer size
this_q = dns.message.make_query(n, t)
this_q.use_edns(0, payload=2000)
q_list.append((l, this_q))
# With an NSID option
# use_edns=0 is not needed if options are specified)
q_list.append(
(
l,
dns.message.make_query(
n, t, options=[dns.edns.GenericOption(dns.edns.OptionType.NSID, b"")]
),
)
)
# With an NSID option, but with use_edns() to specify the options
this_q = dns.message.make_query(n, t)
this_q.use_edns(0, options=[dns.edns.GenericOption(dns.edns.OptionType.NSID, b"")])
q_list.append((l, this_q))
# With a COOKIE
q_list.append(
(
i,
dns.message.make_query(
n,
t,
options=[
dns.edns.GenericOption(
dns.edns.OptionType.COOKIE, b"0xfe11ac99bebe3322"
)
],
),
)
)
# With an ECS option using dns.edns.ECSOption to form the option
q_list.append(
(l, dns.message.make_query(n, t, options=[dns.edns.ECSOption("192.168.0.0", 20)]))
)
for addr, q in q_list:
r = dns.query.udp(q, addr)
if not r.options:
print("No EDNS options returned")
else:
for o in r.options:
print(o.otype.value, o.data)
print()
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