#!/usr/bin/env python3
import copy
import json
import httpx
import dns.flags
import dns.message
import dns.resolver
import dns.rdataclass
import dns.rdatatype
# This shows how to convert to/from dnspython's message object and the
# DNS-over-HTTPS (DoH) JSON form used by Google and Cloudflare, and
# described here:
#
# https://developers.google.com/speed/public-dns/docs/doh/json
#
# There's no need to do this for DoH as dnspython supports the
# standard RFC 8484 protocol which all DoH providers implement. The
# conversion to/from JSON is useful, however, so we show a way to do
# it.
#
# "simple" below means "simple python data types", i.e. things made of
# combinations of dictionaries, lists, strings, and numbers.
def make_rr(simple, rdata):
csimple = copy.copy(simple)
csimple["data"] = rdata.to_text()
return csimple
def flatten_rrset(rrs):
simple = {
"name": str(rrs.name),
"type": rrs.rdtype,
}
if len(rrs) > 0:
simple["TTL"] = rrs.ttl
return [make_rr(simple, rdata) for rdata in rrs]
else:
return [simple]
def to_doh_simple(message):
simple = {"Status": message.rcode()}
for f in dns.flags.Flag:
if f != dns.flags.Flag.AA and f != dns.flags.Flag.QR:
# DoH JSON doesn't need AA and omits it. DoH JSON is only
# used in replies so the QR flag is implied.
simple[f.name] = (message.flags & f) != 0
for i, s in enumerate(message.sections):
k = dns.message.MessageSection.to_text(i).title()
simple[k] = []
for rrs in s:
simple[k].extend(flatten_rrset(rrs))
# we don't encode the ecs_client_subnet field
return simple
def from_doh_simple(simple, add_qr=False):
message = dns.message.QueryMessage()
flags = 0
for f in dns.flags.Flag:
if simple.get(f.name, False):
flags |= f
if add_qr: # QR is implied
flags |= dns.flags.QR
message.flags = flags
message.set_rcode(simple.get("Status", 0))
for i, sn in enumerate(dns.message.MessageSection):
rr_list = simple.get(sn.name.title(), [])
for rr in rr_list:
rdtype = dns.rdatatype.RdataType(rr["type"])
rrs = message.find_rrset(
i,
dns.name.from_text(rr["name"]),
dns.rdataclass.IN,
rdtype,
create=True,
)
if "data" in rr:
rrs.add(
dns.rdata.from_text(dns.rdataclass.IN, rdtype, rr["data"]),
rr.get("TTL", 0),
)
# we don't decode the ecs_client_subnet field
return message
a = dns.resolver.resolve("www.dnspython.org", "a")
p = to_doh_simple(a.response)
print(json.dumps(p, indent=4))
response = httpx.get(
"https://dns.google/resolve?",
verify=True,
params={"name": "www.dnspython.org", "type": 1},
)
p = json.loads(response.text)
m = from_doh_simple(p, True)
print(m)
