dns_over_https.py

"""Resolve an internet host address via via DNS over HTTPS (DoH) (using Cloudflare servers)."""

import mrequests
from mrequests.urlencode import urlencode

DOH_IP = "1.1.1.1"
DOH_SERVER = b"cloudflare-dns.com"
DOH_PATH = "/dns-query"


def gethostbyname(name):
    params = urlencode({"name": name, "type": "A"})
    headers = {
        b"accept": b"application/dns-json",
        b"user-agent": b"mrequests.py",
        b"Host": DOH_SERVER,
    }
    req = mrequests.get("https://{}{}?{}".format(DOH_IP, DOH_PATH, params), headers=headers)
    # print("Status code:", r.status_code)
    if req.status_code == 200:
        reply = req.json()
    else:
        reply = {}

    req.close()

    if reply.get("Status") == 0:
        return [item["data"] for item in reply.get("Answer", [])]


if __name__ == "__main__":
    import sys

    if sys.platform == "esp8266":
        sys.exit("The MicroPython esp8266 port lacks proper TLS cipher support for this example.")

    name = sys.argv[1] if len(sys.argv) > 1 else "httpbin.org"
    res = gethostbyname(name)

    if res:
        print(" ".join(res))
    else:
        print("Could not resolve host name '{}'.".format(name), file=sys.stderr)