From: Bob Halley <halley@dnspython.org>
Date: Tue, 16 Nov 2021 15:17:02 +0000 (-0800)
Subject: Do not impose 2**31-1 bounds on TTL-like things; impose 2**32-1.
X-Git-Tag: v2.2.0rc1~32
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e35de75ae3df365055f62f787b3cbe4ba25364cc;p=thirdparty%2Fdnspython.git

Do not impose 2**31-1 bounds on TTL-like things; impose 2**32-1.
---

diff --git a/dns/ttl.py b/dns/ttl.py
index 8ea52135..df92b2b6 100644
--- a/dns/ttl.py
+++ b/dns/ttl.py
@@ -19,7 +19,13 @@
 
 import dns.exception
 
-MAX_TTL = 2147483647
+# Technically TTLs are supposed to be between 0 and 2**31 - 1, with values
+# greater than that interpreted as 0, but we do not impose this policy here
+# as values > 2**31 - 1 occur in real world data.
+#
+# We leave it to applications to impose tighter bounds if desired.
+MAX_TTL = 2**32 - 1
+
 
 class BadTTL(dns.exception.SyntaxError):
     """DNS TTL value is not well-formed."""
@@ -71,7 +77,7 @@ def from_text(text):
         if not current == 0:
             raise BadTTL("trailing integer")
     if total < 0 or total > MAX_TTL:
-        raise BadTTL("TTL should be between 0 and 2^31 - 1 (inclusive)")
+        raise BadTTL("TTL should be between 0 and 2**32 - 1 (inclusive)")
     return total
 
 
diff --git a/tests/test_bugs.py b/tests/test_bugs.py
index b9636a67..3080e50c 100644
--- a/tests/test_bugs.py
+++ b/tests/test_bugs.py
@@ -42,11 +42,6 @@ class BugsTestCase(unittest.TestCase):
                                      u"a b 100 1 60 3600 86400")
         self.assertEqual(rdata1, rdata2)
 
-    def test_TTL_bounds_check(self):
-        def bad():
-            dns.ttl.from_text("2147483648")
-        self.assertRaises(dns.ttl.BadTTL, bad)
-
     def test_empty_NSEC3_window(self):
         rdata = dns.rdata.from_text(dns.rdataclass.IN, dns.rdatatype.NSEC3,
                                     u"1 0 100 ABCD SCBCQHKU35969L2A68P3AD59LHF30715")
diff --git a/tests/test_message.py b/tests/test_message.py
index ad302984..ff9f550b 100644
--- a/tests/test_message.py
+++ b/tests/test_message.py
@@ -690,7 +690,7 @@ flags QR
         m = dns.message.from_wire(goodwire)
         self.assertIsInstance(m.flags, dns.flags.Flag)
         self.assertEqual(m.flags, dns.flags.Flag.RD)
-        
+
     def test_continue_on_error(self):
         good_message = dns.message.from_text(
 """id 1234
@@ -700,7 +700,7 @@ flags QR AA RD
 ;QUESTION
 www.dnspython.org. IN SOA
 ;ANSWER
-www.dnspython.org. 300 IN SOA . . 1 2 3 4 5
+www.dnspython.org. 300 IN SOA . . 1 2 3 4 4294967295
 www.dnspython.org. 300 IN A 1.2.3.4
 www.dnspython.org. 300 IN AAAA ::1
 """)
@@ -709,15 +709,12 @@ www.dnspython.org. 300 IN AAAA ::1
         bad_wire = wire[:6] + b'\x00\xff' + wire[8:]
         # change AAAA into rdata with rdlen 0
         bad_wire = bad_wire[:-18] + b'\x00' * 2
-        # change SOA MINIMUM field to 0xffffffff (too large)
-        bad_wire = bad_wire.replace(b'\x00\x00\x00\x05', b'\xff' * 4)
         m = dns.message.from_wire(bad_wire, continue_on_error=True)
-        self.assertEqual(len(m.errors), 3)
+        self.assertEqual(len(m.errors), 2)
         print(m.errors)
-        self.assertEqual(str(m.errors[0].exception), 'value too large')
-        self.assertEqual(str(m.errors[1].exception),
+        self.assertEqual(str(m.errors[0].exception),
                          'IPv6 addresses are 16 bytes long')
-        self.assertEqual(str(m.errors[2].exception),
+        self.assertEqual(str(m.errors[1].exception),
                          'DNS message is malformed.')
         expected_message = dns.message.from_text(
 """id 1234
@@ -727,6 +724,7 @@ flags QR AA RD
 ;QUESTION
 www.dnspython.org. IN SOA
 ;ANSWER
+www.dnspython.org. 300 IN SOA . . 1 2 3 4 4294967295
 www.dnspython.org. 300 IN A 1.2.3.4
 """)
         self.assertEqual(m, expected_message)
diff --git a/tests/test_transaction.py b/tests/test_transaction.py
index 9ac9f560..85aa9868 100644
--- a/tests/test_transaction.py
+++ b/tests/test_transaction.py
@@ -209,7 +209,7 @@ def test_bad_parameters(db):
         with pytest.raises(ValueError):
             foo = dns.name.from_text('foo', None)
             rdata = dns.rdata.from_text('in', 'a', '10.0.0.3')
-            txn.add(foo, 0x80000000, rdata)
+            txn.add(foo, 0x100000000, rdata)
         with pytest.raises(TypeError):
             txn.add(foo)
         with pytest.raises(TypeError):