(tests) Ensure pointer loop does not break the server

test.py

@@ -1,5 +1,7 @@
 import asyncio
+import ipaddress
 import socket
+import struct
 import unittest
 
 
@@ -10,6 +12,8 @@ from aiodnsresolver import (
     DnsResponseCode,
     IPv4AddressExpiresAt,
     Message,
+    ResourceRecord,
+    QuestionRecord,
     Resolver,
     pack,
     parse,
@@ -213,6 +217,60 @@ class TestProxy(unittest.TestCase):
         for response in responses:
             self.assertEqual(type(response[0]), IPv4AddressExpiresAt)
 
+    @async_test
+    async def test_sending_pointer_loop_not_affect_later_queries_c(self):
+        resolve, clear_cache = get_resolver(53)
+        self.add_async_cleanup(clear_cache)
+
+        start = DnsProxy(rules=((r'(^.*$)', r'\1'),))
+        stop = await start()
+        self.add_async_cleanup(stop)
+
+        response = await resolve('www.google.com', TYPES.A)
+        self.assertEqual(type(response[0]), IPv4AddressExpiresAt)
+
+        name = b'mydomain.com'
+        question_record = QuestionRecord(name, TYPES.A, qclass=1)
+        record_1 = ResourceRecord(
+            name=name, qtype=TYPES.A, qclass=1, ttl=0,
+            rdata=ipaddress.IPv4Address('123.100.124.1').packed,
+        )
+        response = Message(
+            qid=1, qr=RESPONSE, opcode=0, aa=0, tc=0, rd=0, ra=1, z=0, rcode=0,
+            qd=(question_record,), an=(record_1,), ns=(), ar=(),
+        )
+
+        data = pack(response)
+        packed_name = b''.join(
+            component
+            for label in name.split(b'.')
+            for component in (bytes([len(label)]), label)
+        ) + b'\0'
+
+        occurance_1 = data.index(packed_name)
+        occurance_1_end = occurance_1 + len(packed_name)
+        occurance_2 = occurance_1_end + data[occurance_1_end:].index(packed_name)
+        occurance_2_end = occurance_2 + len(packed_name)
+
+        data_compressed = \
+            data[:occurance_2] + \
+            struct.pack('!H', (192 * 256) + occurance_2 + 4) + \
+            struct.pack('!H', (192 * 256) + occurance_2) + \
+            struct.pack('!H', (192 * 256) + occurance_2 + 2) + \
+            data[occurance_2_end:]
+
+        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        sock.sendto(data_compressed, ('127.0.0.1', 53))
+        sock.close()
+
+        tasks = [
+            asyncio.create_task(resolve('www.google.com', TYPES.A))
+            for _ in range(0, 100000)
+        ]
+        responses = await asyncio.gather(*tasks)
+        for response in responses:
+            self.assertEqual(type(response[0]), IPv4AddressExpiresAt)
+
 
 def get_socket(port):
     def _get_socket():