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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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