Retry failed requests

filter_subdomains.py

@@ -22,8 +22,6 @@ import regexes
 
 DNS_TIMEOUT = 5.0
 
-# TODO Retry failed requests
-
 class DnsResolver(multiprocessing.Process):
     """
     Worker process for a DNS resolver.
@@ -43,7 +41,7 @@ class DnsResolver(multiprocessing.Process):
         self.resolver = dns.resolver.Resolver()
         self.resolver.nameservers = [server]
 
-    def is_subdomain_matching(self, subdomain: str) -> bool:
+    def is_subdomain_matching(self, subdomain: str) -> typing.Optional[bool]:
         """
         Indicates if the subdomain redirects to a first-party tracker.
         """
@@ -60,10 +58,10 @@ class DnsResolver(multiprocessing.Process):
             return False
         except dns.resolver.NoNameservers:
             self.log.warning("All nameservers broken for %s", subdomain)
-            return False
+            return None
         except dns.exception.Timeout:
             self.log.warning("Timeout for %s", subdomain)
-            return False
+            return None
         except dns.name.EmptyLabel:
             self.log.warning("Empty label for %s", subdomain)
             return False
@@ -77,6 +75,13 @@ class DnsResolver(multiprocessing.Process):
         self.log.info("Started")
         for subdomain in iter(self.in_queue.get, None):
             matching = self.is_subdomain_matching(subdomain)
+
+            # If issue, retry
+            if matching is None:
+                # matching = False
+                self.in_queue.put(subdomain)
+                continue
+
             result = (subdomain, matching)
             # self.log.debug("%s", result)
             self.out_queue.put(result)