ris.py: switch to dns query to have builtin cache

ris.py

@@ -1,13 +1,13 @@
 #!/usr/bin/env python
 
 import argparse
-import cymruwhois
 import itertools
 import json
 import pydot
 import random
 import time
 import urllib.request
+from dns import resolver
 
 parser = argparse.ArgumentParser(description='''
 Draw a graph from RIS BGP data. A PNG file will be generated with name
@@ -46,18 +46,24 @@ edges = {}
 
 dot_graph = pydot.Dot('BGPMAP', graph_type='digraph')
 
-cymruwhois_client = cymruwhois.Client()
+resolv = resolver.Resolver()
+resolv.timeout = 0.5
 
 for peer in paths:
     print(peer, paths[peer])
 
     string_prepended_path = ['AS'+v for v in paths[peer][:-1]]
     print(string_prepended_path)
-    cymruwhois_query = cymruwhois_client.lookupmany_dict(string_prepended_path)
 
     for previous_asn, asn in pairwise(paths[peer]):
 
-        as_name = cymruwhois_query['AS'+previous_asn].owner
+        try:
+            as_name = resolv.query(f"AS{previous_asn}.asn.cymru.com", "TXT")
+            as_name = as_name.response.answer[0].to_text().split('|')[4]
+            as_name = as_name.strip().replace("'","").replace('"','')
+        except Exception as e:
+            print(e, previous_asn)
+            as_name = ''
 
         print(as_name)
         edge_tuple = (previous_asn, asn)