dnsdist: Add a regression test for DoH TC=1 fallback to TCP

diff --git a/regression-tests.dnsdist/test_DOH.py b/regression-tests.dnsdist/test_DOH.py
index 527090ac2ee418a6ab702920e7a3f9dfa63978f2..20fe38fd1da596bf9f7dc65ade43aa3a63d7b56b 100644 (file)
--- a/regression-tests.dnsdist/test_DOH.py
+++ b/regression-tests.dnsdist/test_DOH.py
@@ -342,6 +342,49 @@ class TestDOH(DNSDistDOHTest):
         (_, receivedResponse) = self.sendDOHQuery(self._dohServerPort, self._serverName, self._dohBaseURL, caFile=self._caCert, query=query, response=None, useQueue=False)
         self.assertEqual(receivedResponse, expectedResponse)
 
+    def testTruncation(self):
+        """
+        DOH: Truncation over UDP
+        """
+        # the query is first forwarded over UDP, leading to a TC=1 answer from the
+        # backend, then over TCP
+        name = 'truncated-udp.doh.tests.powerdns.com.'
+        query = dns.message.make_query(name, 'A', 'IN')
+        query.id = 0
+        expectedQuery = dns.message.make_query(name, 'A', 'IN', use_edns=True, payload=4096)
+        expectedQuery.id = 0
+        response = dns.message.make_response(query)
+        rrset = dns.rrset.from_text(name,
+                                    3600,
+                                    dns.rdataclass.IN,
+                                    dns.rdatatype.A,
+                                    '127.0.0.1')
+        response.answer.append(rrset)
+
+        # first response is a TC=1
+        tcResponse = dns.message.make_response(query)
+        tcResponse.flags |= dns.flags.TC
+        self._toResponderQueue.put(tcResponse, True, 2.0)
+
+        (receivedQuery, receivedResponse) = self.sendDOHQuery(self._dohServerPort, self._serverName, self._dohBaseURL, query, caFile=self._caCert, response=response)
+        # first query, over UDP
+        self.assertTrue(receivedQuery)
+        receivedQuery.id = expectedQuery.id
+        self.assertEqual(expectedQuery, receivedQuery)
+        self.checkQueryEDNSWithoutECS(expectedQuery, receivedQuery)
+
+        # check the response
+        self.assertTrue(receivedResponse)
+        self.assertEqual(response, receivedResponse)
+
+        # second query, over TCP
+        receivedQuery = self._fromResponderQueue.get(True, 2.0)
+        self.assertTrue(receivedQuery)
+        receivedQuery.id = expectedQuery.id
+        self.assertEqual(expectedQuery, receivedQuery)
+        self.checkQueryEDNSWithoutECS(expectedQuery, receivedQuery)
+
+
     def testSpoof(self):
         """
         DOH: Spoofed