Check if domain has MX record

mx-validate.py

import json
import random
import string
import urllib.request
import urllib.parse

url = "https://dns.google/resolve"

def get_mx_record(domain):
    if validate_domain(domain):
        params = {
            "name": domain,
            "type": "MX",
            "edns_client_subnet": "0.0.0.0/0",
            "random_padding": random_string()
        }
        data = urllib.parse.urlencode(params)
        try:
            with urllib.request.urlopen(url + "?" + data) as response:
                response = json.loads(response.read())
                if response["Status"] == 0 and "Answer" in response:
                    return True
                else:
                    return False
        except Exception as e:
            print(e)


def random_string():
    length = random.randint(10, 50)
    return "".join(random.choice(string.ascii_lowercase) for _ in range(length))


def validate_domain(domain):
    domain = domain.lower().strip(".")

    if not(1 <= len(domain) <= 253):
        return False

    for part in domain.split("."):
        if not(1 <= len(part) <= 63):
            return False

    try:
        domain.encode("idna")
        return True
    except UnicodeError:
        return False


def handler(event, context):
    domain = event["queryStringParameters"]["domain"]
    (_, domain) = domain.split("@")
    return {"statusCode": 200, "body": get_mx_record(domain)}


if __name__ == "__main__":
    print(get_mx_record("google.com"))
    print(get_mx_record("digital.canada.ca"))