support iniziale DNS over Https

lib/doh.py

@@ -0,0 +1,77 @@
+# https://github.com/stamparm/python-doh
+from __future__ import print_function
+
+import json
+import re
+import socket
+import ssl
+import subprocess
+import sys
+
+PY3 = sys.version_info >= (3, 0)
+
+if hasattr(ssl, "_create_unverified_context"):
+    ssl._create_default_https_context = ssl._create_unverified_context
+    DOH_SERVER = "1.1.1.1"              # Note: to prevent potential blocking of service based on DNS name
+else:
+    DOH_SERVER = "cloudflare-dns.com"   # Alternative servers: doh.securedns.eu, doh-de.blahdns.com, doh-jp.blahdns.com
+
+if PY3:
+    import urllib.request
+    _urlopen = urllib.request.urlopen
+    _Request = urllib.request.Request
+else:
+    import urllib2
+    _urlopen = urllib2.urlopen
+    _Request = urllib2.Request
+
+def query(name, type='A', server=DOH_SERVER, path="/dns-query", fallback=True, verbose=False):
+    """
+    Returns domain name query results retrieved by using DNS over HTTPS protocol
+    # Reference: https://developers.cloudflare.com/1.1.1.1/dns-over-https/json-format/
+    >>> query("one.one.one.one", fallback=False)
+    ['1.0.0.1', '1.1.1.1']
+    >>> query("one", "NS")
+    ['a.nic.one.', 'b.nic.one.', 'c.nic.one.', 'd.nic.one.']
+    """
+
+    retval = None
+
+    try:
+        req = _Request("https://%s%s?name=%s&type=%s" % (server, path, name, type), headers={"Accept": "application/dns-json"})
+        content = _urlopen(req).read().decode()
+        reply = json.loads(content)
+
+        if "Answer" in reply:
+            answer = json.loads(content)["Answer"]
+            retval = [_["data"] for _ in answer]
+        else:
+            retval = []
+    except Exception as ex:
+        if verbose:
+            print("Exception occurred: '%s'" % ex)
+
+    if retval is None and fallback:
+        if type == 'A':
+            try:
+                retval = socket.gethostbyname_ex(name)[2]
+            except (socket.error, IndexError):
+                pass
+
+        if retval is None:
+            process = subprocess.Popen(("nslookup", "-q=%s" % type, name), stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+            content = (process.communicate()[0] or "").decode().replace("\r", "")
+
+            if "\n\n" in content and "can't" not in content.lower():
+                answer = content.split("\n\n", 1)[-1]
+                retval = re.findall(r"(?m)^%s.+= ([^=,\n]+)$" % re.escape(name), answer) or re.findall(r"Address: (.+)", answer)
+
+                if not retval:
+                    match = re.search(r"Addresses: ([\s\d.]+)", answer)
+                    if match:
+                        retval = re.split(r"\s+", match.group(1).strip())
+
+    if not PY3 and retval:
+        retval = [_.encode() for _ in retval]
+
+    return retval